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Full text of "The Containment of underground nuclear explosions"

The Containment of 
UNDERGROUND NUCLEAR EXPLOSIONS 





CONGRESS OF THE UNITED STATES OFFICE OF TECHNOLOGY ASSESSMENT 



UiirOSITUuV 

INOV 02 19891 

DOCUMENT 



DOCUMENTS COLLECiiON 
NOV 9 1989 

University of Michigan • Fiiiu Licrury 



Office of Technology Assessment 
Congressional Board of the 101st Congress 

EDWARD M. KENNEDY, Massachusetts. Chairman 
CLARENCE E. MILLER, Ohio. Vice Chairman 



Senate 

ERNEST F. HOLLINGS 
South Carolina 

CLAIBORNE PELL 
Rhode Island 

TED STEVENS 
Alaska 

ORRIN G. HATCH 

Utah 

CHARLES E. GRASSLEY 
Iowa 



JOHN H. GIBBONS 

(Nonvoting) 



Advisory Council 



MORRIS K. UDALL 
Arizona 

GEORGE E. BROWN, JR. 
California 

JOHN D. DINGELL 

Michigan 

DON SUNDQUIST 
Tennessee 

AMO HOUGHTON 
New York 



DAVID S. POTTER, Chairman 
General Motors Corp. (Ret.) 

CHASE N. PETERSON, Vice Chairman 
University of Utah 

CHARLES A. BOWSHER 
General Accounting Office 

MICHEL T. HALBOUTY 
Michel T. Halbouty Energy Co. 



NEIL E. HARL 
Iowa State University 

JAMES C. HUNT 
University of Tennessee 

HENRY KOFFLER 

University of Arizona 

JOSHUA LEDERBERG 
Rockefeller University 



WILLIAM J. PERRY 
H&Q Technology Partners 

SALLY RIDE 
California Space Institute 

JOSEPH E. ROSS 
Congressional Research Service 

JOHN F.M. SIMS 
Usibelli Coal Mine, Inc. 



Director 

JOHN H. GIBBONS 



The Technology Assessment Board approves the release of this report. The views expressed in this report are not necessarily 
those of the Board, OTA Advisory Council, or individual members thereof 



The Containment of 

UNDERGROUND NUCLEAR EXPLOSIONS 




CONGRESS OF THE UNITED STATES OFFICE OF TECHNOLOGY ASSESSMENT 



From the collection of the 






o PreTinger 
V iJibrary 



San Francisco, California 
2008 



Recommended Citation: 

U.S. Congress, Office of Technology Assessment, The Containment of Underground Nuclear 
Explosions, OTA-ISC-414 (Washington, DC: U.S. Government Printing Office, October 
1989). 



Library of Congress Catalog Card Number 89-600707 

For sale by the Superintendent of Documents 

U.S. Government Printing Office, Washington, DC 20402-9325 

(order form can be found in the back of this report) 



Foreword 



Within weeks after the ending of World War II, plans for the first nuclear test series 
"Operation Crossroads" were underway. The purpose then, as now, was to develop new 
weapon systems and to study the effects of nuclear explosions on military equipment. The 
development of the nuclear testing program has been paralled by public opposition from both 
an arms control and an environmental perspective. Much of the criticism is due to the symbolic 
nature of testing nuclear weapons and from the radiation hazards associated with the early 
practice of testing in the aunosphere. Recently, however, specific concerns have also been 
raised about the current underground testing program; namely: 

• Are testing practices safe? 

• Could an accidental release of radioactive material escape undetected? 

• Is the public being fully informed of all the dangers emanating from the nuclear testing 
program? 

These concerns are fueled in part by the secrecy that surrounds the testing program and by 
publicized problems at nuclear weapons production facilities. 

At the request of the House Committee on Interior and Insular Affairs and Senator Orrin 
G. Hatch, OTA undertook an assessment of the containment and monitoring practices of the 
nuclear testing program. This special report reviews the safety of the nuclear testing program 
and assesses the technical procedures used to test nuclear weapons and ensure that radioactive 
material produced by test explosions remains contained underground. An overall evaluation 
considers the acceptability of the remaining risk and discusses reasons for the lack of public 
confidence. 

In the course of this assessment, OTA drew on the experience of many organizations and 
individuals. We appreciate the assistance of the U.S. Government agencies and private 
companies who contributed valuable information, the workshop participants who provided 
guidance and review, and the many additional reviewers who helped ensure the accuracy and 
objectivity of this report. 




JOHN H. GIBBONS 
Director 



Workshop 1: Containment 

Monday, Sept. 26, 1988 

Environmental Research Center 

University of Nevada, Las Vegas 

Neville G. Cook, Chair 

Department of Material Science and Mineral Engineering 

University of California 



Frederick N. App 

Section Leader 

Containment Geophysics 

Los Alamos National Laboratory 

Norman R. Burkhard 

Containment Program Leader 

Lawrence Livermore National Laboratory 

Jim Carothers 

Chairman 

Containment Evaluation Panel 

Lawrence Livermore National Laboratory 

Jack Evemden 

Lawrence Livermore National Laboratory 

U.S. Geological Survey 

Robert A. Fulkerson 
Executive Director 
Citizen Alert 

Jack W. House 

Containment FYogram Manager 

Los Alamos National Laboratory 

Billy C. Hudson 

Deputy Containment Program Leader 

Lawrence Livermore National Laboratory 



Evan Jenkins 

U.S. Geological Survey 

Joseph LaComb 

Chief 

Nevada Operations Office 

Defense Nuclear Agency 

James K. Magruder 

Assistant Manager for Operations and Engineering 

Nevada Operations Office 

U.S. Department of Energy 

Paul Orkild 

U.S. Geological Survey 

Edward W. Peterson 
Containment Project Director 
S-CUBED 

John Stewart 

Director 

Test Operations Division 

Nevada Operations Office 

U.S. Department of Energy 



Workshop 2: Monitoring 

l\iesday, Sept. 27, 1988 

Environmental Research Center 

University of Nevada, Las Vegas 

Melvin W. Carter, Chair 

Neely Professor Emeritus 

Georgia Institute of Technology 

, D A u Bemd Franke 

Lynn R. Anspaugh ^.^^ 

Division Leader 

Environmental Sciences Division Robert A. Fulkerson 

Lawrence Livermore National Laboratory Executive Director 

„ r^u u Citizen Alert 

Bruce Church 

Assistant Manager for Environmental Safety and Michael A. Marelli 

Health Chief, Health Protection Branch 

Nevada Operations Office Health Physics and Environmental Division 

U.S. Department of Energy Nevada Operations Office 

Charles P. Costa U-^- Department of Energy 

Director Darryl Randerson 

Nuclear Radiation Assessment Division Weather Service 

United States Environmental Protection Agency Nuclear Office 

Donald R. EUe 

Chief, Technical Projects Branch 

Health Physics and Environmental Division 

Nevada Operations Office 

U.S. Department of Energy 



OTA Project Staff — The Containment of Underground Nuclear Explosions 

Lionel S. Johns, Assistant Director, OTA 
Energy, Materials, and International Security Division 

Peter Sharfman, International Security and Commerce Program Manager* 
Alan Shaw, International Security and Commerce Program Manager** 

Gregory E. van der Vink, Project Director 

Administrative Staff 

Jannie Home (through November 1988) 

Marie C. Parker (through April 1989) 

Jackie Robinson 

Louise Staley 



1 



"Through February 1989. 
"From March 1989. 



Acknowledgments 



OTA gratefully acknowledges the valuable contributions made by the following: 



Lynn R. Anspaugh 

Lawrence Livermore National Laboratory 

Frederick N. App 

Los Alamos National Laboratory 

Nick Aquilina 

U.S. Department of Energy 

Charles Archambeau 

CIRES, University of Colorado, Boulder 

Stuart C. Black 

U.S. Environmental Protection Agency 

Carter Broyles 

Sandia National Laboratory 

Norman R. Burkhard 

Lawrence Livermore Nationjil Laboratory 

John H. Campbell 

U.S. Department of Energy 

Jim Carothers 

Lawrence Livermore National Laboratory 

Melvin W. Carter 

International Radiation Protection Consultant 

Bruce Church 

U.S. Department of Energy 

Neville G. Cook 

University of California, Berkeley 

Charles P. Costa 

U.S. Environmental Protection Agency 

Jeff Duncan 

Office of Congressman Edward J. Markey 

Donald R. EUe 

U.S. Department of Energy 

Gerald L. Epstein 

John F. Kennedy School of Government, Harvard University 

Jack Evemden 

U.S. Geological Survey 

Anthony Fainberg 

Office of Technology Assessment, U.S. Congress 

Pete Fitzsimmons 

U.S. Department of Energy 

Janet Fogg 

U.S. Department of Energy 

Bemd Franke 

IFEU 

Robert A. Fulkerson 

Citizen Alert 

Larry Gabriel 

Defense Nuclear Agency 



David Graham 

Moore College of Art 

Jack W. House 

Los Alamos National Laboratory 

Billy C. Hudson 

Lawrence Livermore National Laboratory 

Evan Jenkins 

U.S. Geological Survey 

Gerald W. Johnson 

University of California 

Joseph W. LaComb 

Defense Nuclear Agency 

James K. Magruder 

U.S. Department of Energy 

Michael A. Marelli 

U.S. Department of Energy 

LTC Samuel D. McKinney 

Defense Nuclear Agency 

David N. McNelis 

University of Las Vegas, Nevada 

Paul Orkild 

Lawrence Livermore National Laboratory 

Edward W. Peterson 

S-CUBED 

Dorothy F. Pope 

Defense Nuclear Agency 

Darryl Randerson 

Weather Service, Nuclear Office 

Karen Randolph 

U.S. Department of Energy 

R.L. Rhodes 

Diebold, Inc. 

Patrick Rowe 

REECo 

Robert Shirkey 

Defense Nuclear Agency 

John O. Stewart 

U.S. Department of Energy 

Robert Titus 

Weather Service, Nuclear Office 

Dean R. Townsend 

Fenix & Scission, Inc. 

Chris L. West 

U.S. Department of Energy 

Barbara Yoers 

U.S. Department of Energy 



NOTE: OTA appreciates and is grateful for the valuable assistance and thoughtful critiques provided by the contributors. The 
contributors do not, however, necessarily approve, disapprove, or endorse this report. OTA assumes full respwnsibility for the 
ref)on and the accuracy of its contents. 



Contents 

Page 
Chapter 1 . Executive Summary 3 

Chapter 2. The Nuclear Testing Program 11 

Chapter 3. Containing Underground Nuclear Explosions 31 

Chapter 4. Monitoring Accidental Radiation Releases 59 



Chapter 1 

Executive Summary 



CONTENTS 

Page 

INTRODUCTION 3 

HOW SAFE IS SAFE ENOUGH? 3 

HOW SAFE HAS IT BEEN? 3 

SPECinC CONCERNS 5 

OVERALL EVALUATION 6 

Table 

Table Page 
1-1. Releases From Underground Tests 4 



Chapter 1 
Executive Summary 



The chances of an accidental release of radioactive material have been made as remote as possible. 

Public concerns about safety are fueled by concerns about the testing program in general and 

exacerbated by the government' s policy of not announcing all tests. 



INTRODUCTION 

During a nuclear explosion, billions of atoms 
release their energy within a millionth of a 
second, pressures reach several million pounds 
per square inch, and temperatures are as high as 
one-million degrees centigrade. A variety of 
radioactive elements are produced depending on 
the design of the explosive device and the 
contribution of fission and fusion to the explo- 
sion. The half-lives of the elements produced 
range from less than a second to more than a 
million years. 

Each year over a dozen nuclear weapons are 
detonated underground at the Nevada Test Site.^ 
The tests are used to develop new nuclear 
weapons and to assess the effects of nuclear 
explosions on military systems and other hard- 
ware. Each test is designed to prevent the release 
of radioactive material. The objective of each 
test is to obtain the desired experimental infor- 
mation and yet successfully contain the explo- 
sion underground (i.e., prevent radioactive ma- 
terial from reaching the atmosphere). 

HOW SAFE IS SAFE ENOUGH? 

Deciding whether the testing program is safe 
requires a judgment of how safe is safe enough. 
The subjective nature of this judgment is 
illustrated through the decision-making process 
of the Containment Evaluation Panel (CEP) 
which reviews and assesses the containment of 
each test.2 The panel evaluates the probability of 
containment using the terms ' ' high confidence," 
"adequate degree of confidence," and "some 



doubt." But the Containment Evaluation Panel 
has no guidelines that attempt to quantify or 
describe in probabilistic terms what constitutes 
for example, an "adequate degree of confi- 
dence." Obviously, there can never be 100 
percent confidence that a test will not release 
radioactive material. Whether "adequate confi- 
dence" translates into a chance of 1 in 100, 1 in 
1,000, or 1 in 1,000,000, requires a decision 
about what is an acceptable level of risk. In turn, 
decisions of acceptable level of risk can only be 
made by weighing the costs of an unintentional 
release against the benefits of testing. Conse- 
quently, those who feel that testing is important 
for our national security will accept greater risk, 
and those who oppose nuclear testing will find 
even small risks unacceptable. 

Establishing an acceptable level of risk is 
difficult, not only because of the value judg- 
ments associated with nuclear testing, but also 
because the risk is not seen as voluntary by those 
outside the testing program. A public that 
readily accepts the risks associated with volun- 
tary activities — such as sky diving or smoking — 
may still consider the much lower risks associ- 
ated with nuclear testing unacceptable. 

HOW SAFE HAS IT BEEN? 

Some insight into the safety of the nuclear 
testing program can be obtained by reviewing 
the containment record. Releases of radioactive 
material are categorized with terms that describe 
both the volume of material released and the 
conditions of the release: 



'Currenlly, all U.S. nuclear test explosions are conducted at the Nevada Tfesl Site. 

2The Containment Evaluation Panel is a group of representatives from various laboratories and technical consulting organizations who evaluate the 
proposed containment plan for each test without regard to cost or other outside considerations (see ch. 2 for a complete discussion). 



-3- 



4 • Containment of Underground Nuclear Explosions 



Containment Failures: Containment fail- 
ures are unintentional releases of radioactive 
material to the atmosphere due to a failure of the 
containment system. They are termed "vent- 
ings," if they are prompt, massive releases; or 
"seeps," if they are slow, small releases that 
occur soon after the test. 

Late-Time Seeps: Late-time seeps are small 
releases that occur days or weeks after a test 
when gases diffuse through pore spaces of the 
overlying rock and are drawn to the surface by 
decreases in atmospheric pressure. 

Controlled Tunnel Purging: A controlled 
tunnel purging is an intentional release to allow 
either recovery of experimental data and equip- 
ment or reuse of part of the tunnel system. 

Operational Release: Operational releases 
are small, consequential releases that occur 
when core or gas samples are collected, or when 
the drill-back hole is sealed. 

The containment record can be presented in 
different ways depending on which categories of 
releases are included. Reports of total num- 
bers of releases are often incomplete because 
they include only announced tests or releases 
due to containment failure. The upper portion 
of table 1-1 includes every instance (for both 
announced and unannounced tests) where radio- 
active material has reached the atmosphere 
under any circumstances whatsoever since 
the 1970 Baneberry test. 

Since 1970, 126 tests have resulted in radio- 
active material reaching the atmosphere with a 
total release of about 54,000 Curies (Ci). Of this 
amount, 1 1 ,500 Ci were due to containment 
failure and late-time seeps. The remaining 
42,500 Ci were operational releases and con- 
trolled tunnel purgings^ — with Mighty Oak (36,000 
Ci) as the main source. The lower portion of the 
table shows that the release of radioactive 
material from underground nuclear testing since 
Baneberry (54,000 Ci) is extremely small in 
comparison to the amount of material released 



Table 1-1 — Releases From Underground Tests 
(normalized to 12 hours after event*) 

All releases 1971-1988: 

Containment Failures: 

Camphor, 1971" 360 Ci 

Diagonal Line, 1971 6,800 

Riola, 1980 3,100 

Agrini, 1 984 690 

Late-time Seeps: 

Kappeli, 1984 12 

Tierra, 1 984 600 

Latx^uark, 1 986 20 

Bodie. 1986^ 52 

Controlled Tunnel Purgings: 

Hybia Fair, 1974 500 

Hybia Gold, 1977 0.005 

Miners Iron, 1980 0.3 

Huron Landing, 1 982 280 

Mini Jade, 1983 1 

Mill Yard, 1985 5.9 

Diamond Beech, 1985 1.1 

Misty Rain, 1985 63 

Mighty Oak, 1986 36,000 

Mission Ghost, 1 987<= 3 

Operational Releases: 

108 tests from 1970-1988'* 5,500 

Total since Baneberry: 54,000 CI 

Major pre-1 971 releases: 

Platte, 1962 1,900,000 Ci 

Eel, 1962 1 ,900,000 

Des Moines, 1 962 11 ,000,000 

Baneberry, 1970 6,700,000 

26 others from 1958-1970 3,800.000 

Total: 25,300,000 Ci 
Other Releases for Reference 

NTS Atmospheric Testing 1951-1963: . . 12,000.000,000 Ci 

1 Kiloton Aboveground Explosion: 10.000,000 

Chernobyl (estimate): 81 ,000,000 

3R+12 values apply only to containment failures, others are at time of 

release. 
''The Camphor failure includes 140 Ci from tunnel purging, 
^Bodie and Mission Ghost also had drill-back releases. 
''Many of these operational releases are associated with tests that were not 

announced. 
SOURCE: Office of Technology Assessment, 1989. 



by pre-Baneberry underground tests (25,300,000 
Ci), the early atmospheric tests at the Nevada 
Test Site (12,000,000,000 Ci), or even the 
amount that would be released by a single 
1 -kiloton explosion conducted aboveground 
(10,000,000 Ci). 

From the perspective of human health risk: 

If the same person had been standing at the 
boundary of the Nevada Test Site in the area 
of maximum concentration of radioactivity 
for every test since Baneberry (1970), that 



Chapter I — Executive Summary • 5 



person's total exposure would be equivalent 
to 32 extra minutes of normal background 
exposure (or the equivalent of 1/1000 of a 
single chest x-ray). 

A worst-case scenario for a catastrophic 
accident at the test site would be the prompt, 
massive venting of a 150-kiloton test (the largest 
allowed under the 1974 Threshold Test Ban 
Treaty). The release would be in the range of 1 
to 10 percent of the total radiation generated by 
the explosion (compared to 6 percent released 
by the Baneberry test or an estimated 10 percent 
that would be released by a test conducted in a 
hole open to the surface). Such an accident 
would be comparable to a 15-kiloton above- 
ground test, and would release approximately 
150,000,000 Ci. Although such an accident 
would be considered a major catastrophe today, 
during the early years at the Nevada Test Site 25 
aboveground tests had individual yields equal 
to or greater than 15 kilotons. 

SPECIFIC CONCERNS 

Recently, several specific concerns about the 
safety of the nuclear testing program have 
arisen, namely:^ 

1 . Does the fracturing of rock at Rainier Mesa 
pose a danger? 

The unexpected formation of a surface col- 
lapse crater during the 1984 Midas Myth test 
focused concern about the safety of testing in 
Rainier Mesa. The concern was heightened by 
the observation of ground cracks at the top of the 
Mesa and by seismic measurements indicating 
a loss of rock strength out to distances greater 
than the depth of burial of the nuclear device. 
The specific issue is whether the repeated testing 
in Rainier Mesa had fractured large volumes of 
rock creating a "tired mountain" that no longer 
had the strength to successfully contain future 



underground tests. The inference that testing in 
Rainier Mesa poses a high level of risk implies 
that conditions for conducting a test on Rainier 
are more dangerous than conditions for conduct- 
ing a test on Yucca Flat.'* But, in fact, tests in 
Rainier Mesa are buried deeper and spaced 
further apart than comparable tests on Yucca 
Flat.^ Furthermore, drill samples show no evi- 
dence of any permanent decrease in rock 
strength at distances greater than two cavity 
radii from the perimeter of the cavity formed by 
the explosion. The large distance of decreased 
rock strength seen in the seismic measurements 
is almost certainly due to the momentary 
opening of pre-existing cracks during passage of 
the shock wave. Most fractures on the top of the 
mesa are due to surface spall and do not extend 
down to the region of the test. Furthermore, only 
minimal rock strength is required for contain- 
ment. Therefore, none of the conditions of 
testing in Rainier Mesa — burial depth, sepa- 
ration distance, or material strength — imply 
that leakage to the surface is more likely for 
a tunnel test on Rainier Mesa than for a 
vertical drill hole test on Yucca Flat. 

2. Could an accidental release of radioactive 
material go undetected? 

A comprehensive system for detecting radio- 
active material is formed by the combination of: 

• the monitoring system deployed for each 
test; 

• the onsite monitoring system run by the 
Department of Energy (DOE) and; 

• the offsite monitoring system, run by 
Environmental Protection Agency (EPA), 
including the community monitoring sta- 
tions. 

There is essentially no possibility that a 
significant release of radioactive material 



'Detailed analysis of these concerns is included in chs. 3 and 4. 

'' Approximately 90 percent of all nuclear test explosions are vertical drill hole tests conducted on Yucca Flat. See ch. 2 for an explanation of the 
various types of tests. 

'The greater depth of burial is due to convenience. It is easier to mine tunnels lower in the Mesa. 



6 • Containment of Underground Nuclear Explosions 



from an underground test could go unde- 
tected. 

3. Are we running out of room to test at the 
Test Site? 

Efforts to conserve space for testing in 
Rainier Mesa have created the impression that 
there is a "real estate problem" at the test site.^ 
The concern is that a shortage of space would 
result in unsafe testing practices. Although it is 
true that space is now used economically to 
preserve the most convenient locations, other 
less convenient locations are available within 
the test site. Suitable areas within the test site 
offer enough space to continue testing at 
present rates for several more decades. 

4. Do any unannounced tests release radioac- 
tive material? 

A test will be preannounced in the afternoon 
2 days before the test if it is determined that the 
maximum possible yield of the explosion is such 
that it could result in perceptible ground motion 
in Las Vegas. An announcement will be made 
after a test if there is a prompt release of 
radioactive material, or if any late-time release 
results in radioactivity being detected off the test 
site. The Environmental Protection Agency is 
dependent on the Department of Energy for 
notification of any late-time releases within the 
boundaries of the test site. However, if EPA is 
not notified, the release will still be detected by 
EPA's monitoring system once radioactive ma- 
terial reaches outside the test site. If it is judged 
that a late-time release of radioactive mate- 
rial will not be detected outside the bounda- 
ries of the test site, the test may (and often 
does) remain unannounced. 

OVERALL EVALUATION 

Every nuclear test is designed to be contained 
and is reviewed for containment.' In each step of 
the test procedure there is built-in redundancy 



and conservatism. Every attempt is made to 
keep the chance of containment failure as 
remote as possible. This conservatism and 
redundancy is essential, however; because no 
matter how perfect the process may be, it 
operates in an imperfect setting. For each test, 
the containment analysis is based on samples, 
estimates, and models that can only simplify and 
(at best) approximate the real complexities of 
the Earth. As a result, predictions about contain- 
ment depend largely on judgments developed 
from past experience. Most of what is known to 
cause problems — carbonate material, water, 
faults, scarps, clays, etc. — was learned through 
experience. To withstand the consequences of a 
possible surprise, redundancy and conservatism 
is a requirement not an extravagance. Conse- 
quently, all efforts undertaken to ensure a safe 
testing program are necessary, and must con- 
tinue to be vigorously pursued. 

The question of whether the testing program 
is "safe enough" will ultimately remain a value 
judgment that weighs the importance of testing 
against the risk to health and environment, hi 
this sense, concern about safety will continue, 
largely fueled by concern about the nuclear 
testing program itself. However, given the 
continuance of testing and the acceptance of the 
associated environmental damage, the question 
of "adequate safety" becomes replaced with the 
less subjective question of whether any im- 
provements can be made to reduce the chances 
of an accidental release. In this regard, no areas 
for improvement have been identified. This is 
not to say that future improvements will not be 
made as experience increases, but only that 
essentially all suggestions that increase the 
safety margin have been implemented. The 
safeguards built into each test make the 
chances of an accidental release of radioac- 
tive material as remote as possible. 



*See for example: William J. Broad, "Bomb Tests: Tfechnology Advances Against Backdrop of Wide Debate," New York Times. Apr. 15, 1986. 
pp. C1-C3. 



^See ch. 3 for a detailed accounting of the review process. 



Chapter 1 — Executive Summary • 7 



The acceptability of the remaining risk will 
depend on public confidence in the nuclear 
testing program. This confidence currently suf- 
fers from a lack of confidence in the Department 
of Energy emanating from problems at nuclear 
weapons production facilities and from radia- 
tion hazards associated with the past atmos- 
pheric testing program. In the case of the present 
underground nuclear testing program, this mis- 
trust is exacerbated by DOE's reluctance to 
disclose information concerning the testing 
program, and by the knowledge that not all tests 
releasing radioactive material to the atmosphere 
(whatever the amount or circumstances) are 
announced. As the secrecy associated with the 
testing program is largely ineffective in prevent- 
ing the dissemination of information concerning 



the occurrence of tests, the justification for such 
secrecy is questionable.^ 

The benefits of public dissemination of informa- 
tion have been successfully demonstrated by the 
EPA in the area of radiation monitoring. Openly 
available community monitoring stations allow 
residents near the test site to independently 
verify information released by the government, 
thereby providing reassurance to the community 
at large. In a similar manner, public concern 
over the testing program could be greatly 
mitigated if a policy were adopted whereby 
all tests are announced, or at least all tests 
that release radioactive material to the atmos- 
phere (whatever the conditions) are an- 
nounced. 



*See for example; Riley R. Geary, "Nevada Tfcsl Site's dirty little secrets," Bulletin of the Atomic Scientists. April 1989, pp. 35-38. 



Chapter 2 

The Nuclear Testing Program 



CONTENTS 

Page 

INTRODUCTION 11 

THE HISTORY OF NUCLEAR TESTING 11 

LIMITS ON NUCLEAR TESTING 14 

OTHER LOCATIONS OF NUCLEAR TESTS 15 

THE NEVADA TEST SITE 15 

TYPES OF NUCLEAR TESTS 18 

ANNOUNCEMENT OF NUCLEAR TESTS 20 

DETONATION AUTHORITY AND PROCEDURE 22 

Figures 

Figure Page 

2-1. U.S Nuclear Testing 13 

2-2. Nevada Test Site 16 

2-3. Drill-Back Operation 19 

2-4. Locations of Tbnnel Tests in Rainier and Aqueduct Mesas 21 



Chapter 2 

The Nuclear Testing Program 



The nuclear testing program has played a major role in developing new weapon systems and 
determining the effects of nuclear explosions. 



INTRODUCTION 

In the past four decades, nuclear weapons have 
evolved into highly sophisticated and specialized 
devices. Throughout this evolution, the nuclear 
testing program has played a major role in develop- 
ing new weapon systems and determining the effects 
of nuclear explosions. 

THE HISTORY OF NUCLEAR 
TESTING 

On July 16, 1945 the world's first nuclear bomb 
(code named "Trinity") was detonated atop a 
100- foot steel tower at the Alamogordo Bombing 
Range. 55 miles northwest of Alamogordo, New 
Mexico.' The explosion had a yield of 21 kilotons 
(kts), the explosive energy equal to approximately 
21,000 tons of TNT.2 The following month, Ameri- 
can planes dropped two atomic bombs ("Litde 
Boy," 13 kilotons; "Fat Man," 23 kilotons) on the 
Japanese cities of Hiroshima and Nagasaki, ending 
World War II and beginning the age of nuclear 
weapons.^ 

Within weeks after the bombing of Hiroshima and 
Nagasaki, plans were underway to study the effects 
of nuclear weapons and explore further design 
possibilities. A subcommittee of the Joint Chiefs of 
Staff was created, on November 10, 1945, to arrange 
the first series of nuclear test explosions. President 
Truman approved the plan on January 10, 1946. The 
Bikini Atoll was selected as the test site and the 
Bikinians were relocated to the nearby uninhabited 



Rongerik Atoll. Two tests ("Able" and "Baker") 
were detonated on Bikini in June and July of 1946 as 
part of ' ' Operation Crossroads, ' ' a series designed to 
study the effects of nuclear weapons on ships, 
equipment, and material.'* The Bikini Atoll, how- 
ever, was found to be loo small to accommodate 
support facilities for the next test series and so 
"Operation Sandstone" was conducted on the 
nearby Enewetak Atoll. The tests of Operation 
Sandstone ("X-ray," "Yoke," and "Zebra") were 
proof tests for new bomb designs. 

As plans developed to expand the nuclear arsenal, 
the expense, security, and logistical problems of 
tesdng in the Pacific became burdensome. Attention 
turned toward establishing a test site within the 
condnental United States. The Nevada Test Site was 
chosen in December 1950 by President Truman as a 
continental proving ground for testing nuclear weap- 
ons. A month later, the first test — code named 
"Able" — was conducted using a device dropped 
from a B-50 bomber over Frenchman Flat as part of 
a five-test series called "Operation Ranger." The 
five tests were completed within 1 1 days at what was 
then called the "Nevada Proving Ground." 

Although the Nevada Test Site was fully opera- 
tional by 1951, the Pacific continued to be used as a 
test site for developing thermonuclear weapons (also 
called hydrogen or fusion bombs). On October 31, 
1952, the United States exploded the first hydrogen 
(fusion) device on Enewetak Atoll.'' The test, code 
named "Mike," had an explosive yield of 10,4(X) 
kilotons — over 200 times the largest previous test. 



'The Alamogordo Bombing Range is now the White Sands Missile Range. 

2a kilolon (l<t) was originally defined as the explosive equivalent of 1 ,000 tons of TNT. This definition, however, was found to be imprecise for two 
reasons. First, there is some variation in the experimental and theoretical values of the explosive energy released by TNT (although the majority of values 
lie in the range from 900 to 1.100 calories per gram). Second, the term kiloton could refer to a short kiloton (2x10* pounds), a metric kiloton (2.205x10'' 
pounds), or a long kiloton (2.24x 10'' pounds). It was agreed, therefore, during the Manhattan Project that the term "kiloton" would refer to the release 
of 10'^ (1,000,000.000.000) calones of explosive energy. 

3John Malik, "The Yields of the Hiroshima and Nagasaki Nuclear Explosions," l^s Alamos National Laboratory report LA-8819, 1985. 

"The target consisted of a Hect of over 90 vessels assembled in the Bikini Lagoon including three captured German and Japanese ships; surplus U.S. 
cruisers, destroyers, and submarines; and amphibious crafi. 

'The first test of an actual hydrogen bomb (rather than a device located on the surface) was "Cherokee" which was dropped from a plane over Bikini 
Atoll on May 20, 1956. Extensive preparations were made for the test that included the construction of artificial islands to house measuring equipment. 
The elaborate experiments required that the bomb be dropped in a precise location in space. To accomplish this, the Stfalegic Air Command held a 
competition for bombing accuracy. Although the winner hit the correct point in every practice run, during the test the bomb was dropped 4 miles off-largel. 



-11- 



12 • The Containment of Underground Nuclear Explosions 



The test was followed 2 weeks later by the 500 
kiloton explosion "King," the largest fission weapon 
ever tested. 

At the Nevada Test Site, low-yield fission devices 
continued to be tested. Tests were conducted with 
nuclear bombs dropped from planes, shot from 
cannons, placed on top of towers, and suspended 
from balloons. The tests were designed both to 
develop new weapons and to learn the effects of 
nuclear explosions on civilian and military struc- 
tures. Some tests were conducted in conjunction 
with military exercises to prepare soldiers for what 
was then termed "the atomic batdefield." 

In the Pacific, the next tests of thermonuclear 
(hydrogen) bombs were conducted under "Opera- 
tion Castle," a series of six tests detonated on the 
Bikini Atoll in 1954. The first test, "Bravo," was 
expected to have a yield of about 6,000 kilotons. The 
actual yield, however, was 15,000 kilotons — over 
twice what was expected.^ The radioactive fallout 
covered an area larger than anticipated and because 
of a faulty weather prediction, the fallout pattern was 
more easterly than expected. A Japanese fishing 
boat, which had accidentally wandered into the 
restricted zone without being detected by the Task 
Force, was showered with fallout. When the fishing 
boat docked in Japan, 23 crew members had 
radiation sickness. The radio operator died of 
infectious hepatitis, probably because of the large 
number of required blood transfusions.^ The faulty 
fallout prediction also led to the overexposure of the 
inhabitants of two of the Marshall Islands 100 miles 
to the East. In a similar though less severe accident, 
radioactive rain from a Soviet thermonuclear test fell 
on Japan.* These accidents began to focus world- 
wide attention on the increased level of nuclear 
testing and the dangers of radioactive fallout. Public 
opposition to atmospheric testing would continue to 
mount as knowledge of the effects of radiation 
increased and it became apparent that no region of 
the world was untouched.^ 

Attempts to negotiate a ban on nuclear testing 
began at the United Nations Disarmament Confer- 



ence in May 1955. For the next several years efforts 
to obtain a test ban were blocked as agreements in 
nuclear testing were linked to progress in other arms 
control agreements and as differences over verifica- 
tion requirements remained unresolved. In 1958, 
President Eisenhower and Soviet Premier Khrushchev 
declared, through unilateral public statements, a 
moratorium on nuclear testing and began negotia- 
tions on a comprehensive test ban. The United States 
adopted the moratorium after conducting 1 3 tests in 
seven days at the end of October 1958. Negotiations 
broke down first over the right to perform onsite 
inspections, and then over the number of such 
inspections. In December 1959, President Eisen- 
hower announced that the United States would no 
longer consider itself bound by the "voluntary 
moratorium" but would give advance notice if it 
decided to resume testing. Meanwhile (during the 
moratorium), the French began testing their newly 
acquired nuclear capability. The Soviet Union, 
which had announced that it would observe the 
moratorium as long as the western powers would not 
test, resumed testing in September 1 961 with a series 
of the largest tests ever conducted. The United States 
resumed testing two weeks later (figure 2-1)."' 

Public opposition to nuclear testing continued to 
mount. Recognizing that the U.S. could continue its 
development program solely through underground 
testing and that the ratification of a comprehensive 
test ban could not be achieved. President Kennedy 
proposed a limited ban on tests in the atmosphere, 
the oceans, and space. The Soviets, who through 
their own experience were convinced that their test 
program could continue underground, accepted the 
proposal. With both sides agreeing that such a treaty 
could be readily verified, the Limited Test Ban 
Treaty (LTBT) was signed in 1963, banning all 
aboveground or underwater testing. 

In addition to military applications, the engineer- 
ing potential of nuclear weapons was recognized by 
the inid-1950's. The Plowshare Program was formed 
in 1957 to explore the possibility of using nuclear 
explosions for peaceful purposes." Among the 



*Bravo was Ihe largest test ever detonated by the United States. 

^See "The Voyage of the Lucky Dragon," Ralph E. Lapp, 1957, Harper & Brothers Publishers, New York. 

'"Arms Control and Disarmament Agreements," United States Arms Control and Disarmament Agency, Washington, DC, 1982 Edition, p. 34. 
'Since the large thermonuclear tests, all people have slrontium-90 (a sister element of calcium) in their bones, and cesiuni-137 (a sister element of 
potassium) in their muscle. Also, the amount ofiodine-131 in milk in the United States correlates with the frequency of atmospheric testing. 
'"See "Arms Control and Disarmament Agreements," United States Arms Control and Disarmament Agency. 1982 edition. 
"The name is from ". . . . they shall beat their swords into plowshares," Isaiah 2:4. 



Chapter 2 — The Nuclear Testing Program • 75 



Figure 2-1— U.S. Nuclear Testing 

LTBT TTBT 



Key: LTBT = 1963 Limited Test Ban Treaty 
TTBT = 1974 Threshold Test Ban Treaty 




1945 1950 

I I Above-ground tests 

I Underground tests 

SOURCE: Data from tho Swedish Defense Research Institute. 

applications considered were the excavation of 
canals and harbors, the creation of underground 
storage cavities for fuel and waste, the fracturing of 
rock to promote oil and gas flow, and the use of 
nuclear explosions to cap oil gushers and extinguish 
fires. It was reported that even more exotic applica- 
tions, such as melting glaciers for irrigation, were 
being considered by the Soviet Union. 

The first test under the Plowshare Program, 
"Gnome," was conducted 4 years later to create an 
underground cavity in a large salt deposit. The next 
Plowshare experiment, Sedan in 1962, used a 104 
kiloton explosion to excavate 12 million tons of 
earth. In 1965, the concept of "nuclear excavation" 
was refined and proposed as a means of building a 
second canal through Panama. '^ Three nuclear 
excavations were tested under the Plowshare pro- 
gram ("Cabriolet," Jan. 26, 1968; "Buggy," Mar. 
12, 1968; and "Schooner," Dec. 12, 1968). Schoo- 
ner, however, released radioactivity off site and, as 
a consequence, no future crater test was approved. 
Consideration of the radiological and logistical 
aspects of the project also contributed to its demise. 



Estimates of the engineering requirements indicated 
that approximately 250 separate nuclear explosions 
with a total yield of 1 20 megatons would be required 
to excavate the canal through Panama. Furthermore, 
fallout predictions indicated that 16,000 square 
kilometers of territory would need to be evacuated 
for the duration of the operation and several months 
thereafter. '3 Because it was also clear that no level 
of radioactivity would be publicly acceptable, the 
program was terminated in the early 1970s. 

In 1974, President Richard Nixon signed the 
Threshold Test Ban Treaty (TTBT) restricting all 
nuclear test explosions to a defined test site and to 
yields no greater than 150 kilotons. As a result, all 
U.S. underground nuclear tests since 1974 have been 
conducted at the Nevada Test Site. As part of the 
earlier 1963 Limited Test Ban Treaty, the United 
States established a series of safeguards. One of 
them, "Safeguard C," requires the United States to 
maintain the capability to resume atmospheric 
testing in case the treaty is abrogated. The Depart- 
ment of Energy (DOE) and the Defense Nuclear 
Agency continue today to maintain a facility for the 



'^Thc 1956 war over the Suez Canal created the first specific proposals for using nuclear explosions to create an alternative canal. 
"Bruce A. Bolt, "Nuclear Explosions and Earthquakes, The Parted Veil" San Francisco. CA: W.H. Freeman & Co., 1976. pp. 192-196. 



14 • The Containment of Underground Nuclear Explosions 




Photo credit: David Graham. 19 



Sedan Crater 



atmospheric testing of nuclear weapons at the 
Johnston Atoll in the Pacific Ocean. 



LIMITS ON NUCLEAR TESTING 

The testing of nuclear weapons by the United 
States is currently restricted by three major treaties 
that were developed for both environmental and 
arms control reasons. The three treaties are: 

1. the 1963 Limited Nuclear Test Ban Treaty, 
which bans nuclear explosions in the atmosphere, 
outer space, and underwater, and restricts the release 
of radiation into the atmosphere, 

2. the 1974 Threshold Test Ban Treaty, which 
restricts the testing of underground nuclear weapons 
by the United States and the Soviet Union to yields 
no greater than 150 kilotons, and 

3. the 1976 Peaceful Nuclear Explosions Treaty 
(PNET), which is a complement to the Threshold 
Test Ban Treaty (riBT). It restricts individual 
peaceful nuclear explosions (PNEs) by the United 
States and the Soviet Union to yields no greater than 



150 kilotons, and group explosions (consisting of a 
number of individual explosions detonated simulat- 
enously) to aggregate yields no greater than 1 ,500 
kilotons. 

Although both the 1974 TTBT and the 1976 
PNET remain unratified, both the United States and 
the Soviet Union have expressed their intent to abide 
by the yield limit. Because neither country has 
indicated an intention not to ratify the treaties, both 
parties are obligated to refrain from any acts that 
would defeat their objective and purpose.'"* Conse- 
quently, all nuclear test explosions compliant with 
treaty obligations must be conducted underground, 
at specific test sites (unless a PNE), and with yields 
no greater than 150 kilotons. The test must also be 
contained to the extent that no radioactive debris is 
detected outside the territorial limits of the country 
that conducted the test.'^ Provisions do exist, 
however, for one or two slight, unintentional breaches 
per year of the 150 kiloton limit due to the technical 
uncertainties associated with predicting the exact 
yields of nuclear weapons tests. '^ 



'''Art. 18, 1969 Vienna Convention on the Law of Treaties. 
''An. I, Kb), 1963 Limited Tfest Ban Treaty. 

'^Statement of understanding included with the transmittal documents accompanying the Threshold Test Ban Treaty and the Peaceful Nuclear 
Explosions Treaty when submitted to the Senate for advice and consent to ratification on July 29, 1979. 



Chapter 2 — The Nuclear Testing Program • 15 



OTHER LOCATIONS OF 
NUCLEAR TESTS 

U.S. nuclear test explosions were also conducted 
in areas other than the Pacific and the Nevada Test 
Site. 

Three tests with yields of 1 to 2 kilotons were 
conducted over the South Atlantic as "Operation 
Argus." The tests ("Argus I," Aug. 27, 1958; 
"Argus II," Aug. 30, 1958; and "Argus III," Sept. 
6, 1958) were detonated at an altitude of 300 miles 
to assess the effects of high-altitude nuclear detona- 
tions on communications equipment and missile 
performance. 

Five tests, all involving chemical explosions but 
with no nuclear yield, were conducted at the Nevada 
Bombing Range to study plutonium dispersal. The 
tests, "Project 57 NO 1," April 24, 1957; "Double 
Tracks," May 15, 1963; "Clean Slate I," May 25, 
1963; "Clean Slate II," May 31, 1963; and "Clean 
Slate III," June 9, 1963; were safety tests to establish 
storage and transportation requirements. 

Two tests were conducted in the Tatum Salt Dome 
near Hattiesburg, Mississippi, as part of the Vela 
Uniform experiments to improve seismic methods of 
detecting underground nuclear explosions. The first 
test "Salmon," October 22, 1964, was a 5.3 kiloton 
explosion that formed an underground cavity. The 
subsequent test "Sterling," December 3, 1966, was 
0.38 kt explosion detonated in the cavity formed by 
Salmon. The purpose of the Salmon/Sterling experi- 
ment was to assess the use of a cavity in reducing the 
size of seismic signals produced by an underground 
nuclear test.' ^ 

Three joint government-industry tests were con- 
ducted as part of the Plowshare Program to develop 
peaceful uses of nuclear explosions. The experi- 
ments were designed to improve natural gas extrac- 
tion by fracturing rock formations. The first test, 
"Gasbuggy," was a 29 kiloton explosion detonated 
on December 10, 1967, near Bloomfield, New 
Mexico. The next two were in Colorado: "Rulison" 
was a 40 kiloton explosion, detonated near Grand 
Valley on September 10, 1969; and "Rio Blanco" 



was a salvo shot of three explosions, each with a 
y ield of 3 3 kt, detonated near Rifle on May 17, 1973. 

Three tests were conducted on Amchitka Island, 
Alaska. The first (October 29, 1965), "Long Shot" 
was an 80 kiloton explosion that was part of the Vela 
Uniform project. The second test, "Milrow," Octo- 
ber 2, 1969, was about a one megaton explosion to 
"calibrate" the island and assure that it would 
contain a subsequent test of the Spartan Anti- 
Ballistic Missile warhead. The third test, "Canni- 
kin," November 6, 1971, was the Spartan warhead 
test with a reported yield of "less than five 
megatons." This test, by far the highest-yield 
underground test ever conducted by the United 
States, was too large to be safely conducted in 
Nevada.'* 

Three individual tests were also conducted in 
various parts of the western United States. "Gnome" 
was a 3 kiloton test conducted on December 10, 
1961 near Carlsbad, New Mexico, to create a large 
underground cavity in salt as part of a multipurpose 
experiment. One application was the possible use of 
the cavity for the storage of oil and gas. "Shoal" 
was a 1 2 kiloton test conducted on October 26, 1 963 
near Fallon, Nevada as part of the Vela Uniform 
project. "Faultless" was a test with a yield of 
between 200 and 1 ,(X)0 kiloton that was exploded on 
January 19, 1968, at a remote area near Hot Creek 
Valley, Nevada. FauUless was a ground-motion 
calibration test to evaluate a Central Nevada Supple- 
mental Test Area. The area was proposed as a 
alternative location for high-yield tests to decrease 
the ground shaking in Las Vegas. 

THE NEVADA TEST SITE 

The Nevada Tfest Site is located 65 miles north- 
west of Las Vegas. It covers 1,350 square miles, an 
area slightiy larger than Rhode Island (figure 2-2). 
The test site is surrounded on three sides by an 
additional 4,(X)0 to 5,000 square miles belonging to 
Nellis Air Force Base and the Tonopah Tfest Range. 
The test site has an administrative center, a control 
point, and areas where various testing activities are 
conducted. 

At the southern end of the test site is Mercury, the 
administrative headquarters and supply base for 



"For a complete discussion of the issues related to Seismic Verification see, U.S. Congress, Office of Tfechnology Assessment, Seismic Verification 
of Nuclear Testing Treaties, OTA-ISC-361, Washington, DC: U.S. Government Printing Office, May 1988. 

"The predictions of ground motion suggested that an unacceptable amount (in terms of claims and dollars) of damage would occur to structures if 
the test was conducted in Nevada. 



76 • The Containment of Underground Nuclear Explosions 



Figure 2-2 — Nevada Test Site 




SOURCE: Modified from Department of Energy. 



DOE contractors and other agencies involved in 
Nevada Operations. Mercury contains a limited 
amount of housing for test site personnel and other 
ground support facilities. 

Near the center of the test site, overlooking 
Frenchman Flat to the South and Yucca Flat to the 
North, is the Control Point (CP). The CP is the 
command headquarters for testing activities and is 
the location from which all tests are detonated and 
monitored. 

Frenchman Flat is the location of the first nuclear 
test at the test site. A total of 14 atmospheric tests 
occurred on Frenchman Flat between 1951 and 
1962. Most of these tests were designed to determine 



the effects of nuclear explosions on structures and 
military objects. The area was chosen for its flat 
terrain which permitted good photography of deto- 
nations and fireballs. Also, 10 tests were conducted 
underground at Frenchman Flat between 1965 and 
1 97 1 . Frenchman Flat is no longer used as a location 
for testing. The presence of carbonate material 
makes the area less suitable for underground testing 
than other locations on the test site.'*^ 

Yucca Flat is where most underground tests occur 
today. These tests are conducted in vertical drill 
holes up to 10 feet in diameter and from 600 ft to 
more than 1 mile deep. It is a valley 10 by 20 miles 
extending north from the CP. Tests up to about 300 
kilotons in yield have been detonated beneath Yucca 



"Dtiring an explosion, carbonate material can form carbon dioxide which, under pressure, can cause venting. 



Chapter 2 — The Nuclear Testing Program • 17 




iiH^^-i >^ 



■smx9M ^it 

Photo credit Da^d Grahan 



Test Debris on Frenchman Flat 



Flat, although Pahute Mesa is now generally re- 
served for high-yield tests. 

Tests up to 1 ,000 kilotons in yield have occurred 
beneath Pahute Mesa, a 1 70 square mile area in the 
extreme north-western part of the test site. The deep 
water table of Pahute Mesa permits underground 
testing in dry holes at depths as great as 2,100 feet. 
The distant location is useful for high-yield tests 
because it minimizes the chance that ground motion 
will cause damage offsite. 

Both Livermore National Laboratory and Los 
Alamos National Laboratory have specific areas of 
the test site reserved for their use. Los Alamos uses 
areas 1, 3,4(east), 5, and 7 in Yucca Flat and area 19 



on Pahute Mesa; Livermore uses areas 2, 4(west), 8, 
9, and 10 in Yucca Rat, and area 20 on Pahute Mesa 
(figure 2-2). While Los Alamos generally uses 
Pahute Mesa only to relieve schedule conflicts on 
Yucca Flat, Livermore normally uses it for large test 
explosions where the depth of burial would require 
the test to be below the water table on Yucca Rat. 

The Nevada Tfest Site employs over 11,000 
people, with about 5,000 of them working on the site 
proper. The annual budget is approximately $1 
billion divided among testing nuclear weapons 
(81%) and the development of a storage facility for 
radioactive waste (19%). The major contractors are 
Reynolds Electrical & Engineering Co., Inc. (REECo), 



18 • The Containment of Underground Nuclear Explosions 




Photo credit Department of Energy 



Aerial View of Yucxia Flat 



Edgerton, Germeshausen & Greer (EG&G), Fenix & 
Scisson, Inc., and Holmes & Narver, Inc. REECo has 
5,000 employees at the test site for construction, 
maintenance, and operational support, which in- 
cludes large diameter drilling and tunneling, on-site 
radiation monitoring, and operation of base camps. 
EG&G has 2,200 employees, who design, fabricate, 
and operate the diagnostic and scientific equipment. 
Fenix & Scisson, Inc. handles the design, research, 
inspection, and procurement for the drilling and 
mining activities. Holmes & Narver, Inc. has respon- 
sibility for architectural design, engineering design, 
and inspection. In addition to contractors, several 
government agencies provide support to the testing 
program: the Environmental Protection Agency 
(EPA) has responsibility for radiation monitoring 
outside the Nevada Test Site; the National Oceanic 
and Atmospheric Administration (NOAA) provides 
weather analyses and predictions; and the United 
States Geological Survey (USGS) provides geologi- 
cal, geophysical, and hydrological assessments of 
test locations. 



TYPES OF NUCLEAR TESTS 

Presently, an average of more than 12 tests per 
year are conducted at the Nevada Test Site. Each test 
is either at the bottom of a vertical drill hole or at the 
end of a horizontal tunnel. The vertical drill hole 
tests are the most common (representing over 90% 
of all tests conducted) and occur either on Yucca Flat 
or, if they are large-yield tests, on Pahute Mesa. 
Most vertical drill hole tests are for the purpose of 
developing new weapon systems. Horizontal tunnel 
tests are more costly and time-consuming. They only 
occur once or twice a year and are located in tunnels 
mined in the Rainier and Aqueduct Mesas. TUnnel 
tests are generally for evaluating the effects (radia- 
tion, ground shock, etc.) of various weapons on 
military hardware and systems. In addition, the 
United Kingdom also tests at a rate of about once a 
year at the Nevada Test Site. 

It takes 6 to 8 weeks to drill a hole depending on 
depth and location. The holes used by Livermore and 
Los Alamos differ slightly. Los Alamos typically 
uses holes with diameters that range from about 4 



Chapter 2 — The Nuclear Testing Program •19 



Figure 2-3— Drill-Back Operation 

Drill rig 




Photo credit Department of Energy 

Emplacement Tower for Vertical Drill Hole Test 

1/2 up to 7 ft; while Livermore typically uses 8-ft 
diameter holes and an occasional 10-ft diameter 
hole.^° Livermore usually places its experimental 
devices above the water table to avoid the additional 
time and expense required to case holes below the 
water table. 

When the device is detonated at the bottom of a 
vertical drill hole, data from the test are transmitted 
through electrical and fiber-optic cables to trailers 
containing recording equipment. Performance infor- 
mation is also determined from samples of radioac- 
tive material that are recovered by drilling back into 
the solidified melt created by the explosion (figure 
2-3). On rare occasions, vertical drill holes have 
been used for effects tests. One such test, "Huron 
King," used an initially open, vertical "line-of- 
sight" pipe that extended upwards to a large 



SOURCE: Modified from Micfiael W Butler. Pastshot Drilling Handbook, 
Lawrence Livermore National Laboratory, Jan. 19. 1984. 



enclosed chamber located at the surface. The cham- 
ber contained a satellite inside a vacuum to simulate 
the conditions of space. The radiation from the 
explosion was directed up the hole at the satellite. 
The explosion was contained by a series of mechan- 
ical pipe closures that blocked the pipe immediately 
after the initial burst of radiation. The purpose of the 
test was to determine how satellites might be 
affected by the radiation produced by a nuclear 
explosion. 

TUnnel tests occur within horizontal tunnels that 
are drilled into the volcanic rock of Rainier or 
Aqueduct Mesa. From 1970 through 1988, there 



^OLivermore has considered the use of 12 ft diameter holes, but has not yet used one. 



20 • The Containment of Underground Nuclear Explosions 




Photo credit David Graham. 1986 



Huron King Test 



have been 31 tunnel tests conducted in Rainier and 
Aqueduct Mesas (figure 2-4). It may require 12 
months of mining, using three shifts a day, to remove 
the 1 million cubic feet of rock that may be needed 
to prepare for a tunnel test. 

Effects tests performed within mined tunnels are 
designed to determine the effects of nuclear explosion- 
produced radiation on missile nose cones, warheads, 
satellites, communications equipment, and other 
military hardware. The tunnels are large enough so 
that satellites can be tested at full scale in vacuum 
chambers that simulate outer space. The tests are 
used to determine how weapons systems will 
withstand radiation that might be produced by a 
nearby explosion during a nuclear war. Nuclear 



effects tests were the first type of experiments 
performed during trials in the Pacific and were an 
extensive part of the testing program in the 1950s. At 
that time, many tests occurred above ground and 
included the study of effects on structures and civil 
defense systems. 

Effects tests within cavities provide a means of 
simulating surface explosions underground. A large 
hemispherical cavity is excavated and an explosion 
is detonated on or near the floor of the cavity. The 
tests are designed to assess the capability of above- 
ground explosions to transmit energy into the 
ground. This information is used to evaluate the 
capability of nuclear weapons to destroy such targets 
as missile silos or underground command centers. 



Chapter 2 — The Nuclear Testing Program •21 



Figure 2-4 — Locations of Tunnel Tests in Rainier and Aqueduct Mesas 



Aqueduct 
Mesa 



U12p 



Topographic 
of Mesa 



Rainier 
Mesa 



U12e 



• Test location 
Tunnels 



3,000 ft 



U12g 



SOURCE: Modified from Defense Nuclear Agency 



ANNOUNCEMENT OF 
NUCLEAR TESTS 

The existence of each nuclear test conducted prior 
to the signing of the LTBT on August 5, 1963, has 
been declassified. Many tests conducted since the 
signing of the LTBT, however, have not been 
announced. Information concerning those tests is 
classified. The yields of announced tests are pres- 



ently reported only in the general categories of either 
less than 20 kilotons, or 20 to 150 kilotons. The 
DOE's announcement pohcy is that a test will be 
pre-announced in the afternoon 2 days before the test 
if it is determined that the maximum credible yield 
is such that it could result in perceptible ground 
motion in Las Vegas. The test will be post an- 
nounced if there is a prompt release of radioactive 
material or if any late-time release results in 



22 • The Containment of Underground Nuclear Explosions 



■amm^m^tm-'iiiiu 





■m 




Phoio aedil: David Graham. 1988 



Tunnel Entrance 



radioactive material being detected off the test site. 
In the case of late-time release, however, the test will 
be announced only if radioactive material is de- 
tected off -site. 

Starting with Trinity, names have been assigned 
to all nuclear tests. The actual nuclear weapon or 
device and its description are classified. Conse- 
quently, test planners assign innocuous code words 
or nicknames so that they may refer to planned tests. 
Early tests used the military phonetic alphabet 
(Able, Baker, Charlie, etc.). As more tests took 
place, other names were needed. They include 
names of rivers, mountains, famous scientists, small 
mammals, counties and towns, fish, birds, vehicles, 
cocktails, automobiles, trees, cheeses, wines, fab- 
rics, tools, nautical terms, colors, and so forth. 



DETONATION AUTHORITY AND 
PROCEDURE 

The testing of nuclear weapons occurs under the 
authority of the Atomic Energy Act of 1946 (as 
amended in 1954), which states: 

"The development, use, and control of Atomic 
Energy shall be directed so as to make the maximum 
contribution to the general welfare, subject at all 
times to the paramount objective of making the 
maximum contribution to the common defense and 
security." 

The act authorizes the U.S. Atomic Energy 
Commission (now Department of Energy), to "con- 



Chapter 2 — The Nuclear Testing Program • 23 




Photo credit: Department of Energy 



Interior Tunnel 



duct experiments and do research and development 
work in the military application of atomic energy." 

The fiscal year testing program receives authori- 
zation from the President. Each fiscal year, the 
Department of Defense (DoD), Department of En- 
ergy (DOE), and the weapons laboratories (Law- 



rence Livermore National Laboratory and Los Alamos 
National Laboratory) develop a nuclear testing 
program. The Secretary of Energy proposes the 
upcoming year's program in a letter to the President 
through the National Security Council. The National 
Security Council solicits comments on the test 
program from its members and incorporates those 



24 • The Containment of Underground Nuclear Explosions 




Photo credit: Defense Nuclear Agency 



End of Tunnel 



comments in its recommendation letter to the 
President. The Nevada Operations Office plans the 
individual tests with the responsible laboratory. 

Both Livermore and Lx)s Alamos maintain stock- 
piles of holes in various areas of the test site.^' When 
a specific test is proposed, the lab will check its 



inventory to see if a suitable hole is available or if a 
new one must be drilled. 

Once a hole is selected, the sponsoring laboratory 
designs a plan to fiU-in (or "stem") the hole to 
contain the radioactive material produced by the 
explosion. The USGS and Earth scientists from 
several organizations analyze the geology surround- 



2'Each laboratory operates its own drilling crews continuously to maximize the economy of the drilling operation. 



Chapter 2 — The Nuclear Testing Program • 25 




Photo credit: Defense Nuclear Agency 



Tunnel Cavity 



ing the proposed hole and review it for containment. 
The laboratory then presents the full containment 
plan to the Containment Evaluation Panel (CEP) 2 
to 3 months in advance of the detonation. The CEP 
is a panel of experts that review and evaluate the 
containment plan for each test.^^ Each CEP panel 
member goes on record with a statement concerning 
his judgment of the containment. The CEP chairman 
summarizes the likelihood of containment and gives 
his recommendation to the manager of Nevada 
Operations. 

Following the CEP meeting, a Detonation Au- 
thority Request (DAR) package is prepared. The 
DAR package contains a description of the proposed 
test, the containment plan, the recommendations of 
the CEP, the chairman's statement, a review of the 



environmental impact, a nuclear safety study,^^ a 
review of compliance with the TTBT, the public 
announcement plans, and any noteworthy aspects of 
the test. The DAR package is sent to the DOE Office 
of Mihtary Application for approval. Although test 
preparations are underway throughout the approval 
process, no irreversible action to conduct the test is 
taken prior to final approval. 

After the test has been approved, the Test Group 
Director of the sponsoring Laboratory will then 
request "authority to move, emplace, and stem" the 
nuclear device from the Nevada test site "Test 
Controller" for that specific test. The Test Control- 
ler also has an advisory panel consisting of a 
Chairman and three other members. The Chairman 
(called the Scientific Advisor) is a senior scientist 



^^See Ch. 3, "Containment Evaluation Panel." 

23The nuclear safety study prepared by DOE Safely Division contains safety considerations not related to containment, such as the possibility of 
premature or inadvertent detonation. 

^''In the case of tests sponsored by the Defense Nuclear Agency (DNA), the Scientific Advisor is from Sandia National Laboratory. 



26 • The Containment of Underground Nuclear Explosions 



from the sponsoring laboratory. ^^ The three mem- 
bers are all knowledgeable about the weapons- 
testing program and consist of: 

1. an EPA senior scientist with expertise in 
radiation monitoring, 

2. a weather service senior scientist knowledgea- 
ble in meteorology, and 

3. a medical doctor with expertise in radiation 
medicine. 

Once the test has been approved for execution by the 
Test Controller's panel, the Test Controller has sole 
responsibility to determine when or whether the test 
will be conducted. The Test Controller and Advisory 
Panel members conduct the following series of 
technical meetings to review the test:^ 

D-7 Safety Planning Meeting: The "D-7 Safety 
Planning Meeting" is held approximately 1 week 
before the test. This meeting is an informal review 
of the test procedure, the containment plan, the 
expected yield, the maximum credible yield, the 
potential for surface collapse, the potential ground 
shock, the expected long-range weather conditions, 
the location of radiation monitors, the location of all 
personnel, the security concerns (including the 
possibility of protesters intruding on the test site), 
the countdown, the pre-announcement policy, and 
any other operational or safety aspects related to the 
test. 

D-1 Safety Planning Meeting: The day before the 
test, the D-1 Safety Planning Meeting is held. This 
is an informal briefing that reviews and updates all 
the information discussed at the D-7 meeting. 

D-1 Containment Briefing: The D-1 Containment 
Briefing is a formal meeting. The laboratory reviews 
again the containment plan and discusses whether all 
of the stemming and other containment require- 
ments were met. The meeting determines the extent 
to which the proposed containment plan was carried 
out in the field.^^ The laboratory and contractors 
provide written statements on their concurrence of 
the stemming plan. 

D-1 Readiness Briefing: The D-1 Readiness 
Briefing is a formal meeting to review potential 



weather conditions and the predicted radiation 
fallout pattern for the case of an accidental venting. 

The night before the test, the weather service 
sends out observers to release weather balloons and 
begin measuring wind direction and speed to a 
height of 1 ,400 ft above the ground. The area around 
the test (usually all areas north of the Control Point 
complex) is closed to all nonessential personnel. The 
Environmental Protection Agency deploys monitor- 
ing personnel off-site to monitor fallout and coordi- 
nate protective measures, should they be necessary. 

D-Day Readiness Briefing: The morning of the 
test, the Test Controller holds the "D-Day Readi- 
ness Briefing." At this meeting, updates of weather 
conditions and forecasts are presented. In additon, 
the weather service reviews the wind and stability 
measurements to make final revisions to the fallout 
pattern in the event of an accidental venting. The 
fallout pattern is used to project exposure rates 
throughout the potential affected area. The exposure 
rates are calculated using the standard radiological 
models of whole-body exposure and infant thyroid 
dose from a family using milk cows in the fallout 
region. The status of on-site ground-based and 
airborne radiation monitoring is reviewed. The 
location of EPA monitoring personnel is adjusted to 
the projected fallout pattern, and the location of all 
personnel on the test site is confirmed. At the end of 
the meeting, the Scientific Advisor who is chairman 
of the Test Controller's Advisory Panel makes a 
recommendation to the Test Controller to proceed or 
delay. 

If the decision is made to proceed, the Test 
Controller gives permission for the nuclear device to 
be armed. The operation of all radiation monitors, 
readiness of aircraft, location of EPA personnel, etc., 
are confirmed. If the status remains favorable and the 
weather conditions are acceptable, the Test Control- 
ler gives permission to start the countdown and to 
fire. If nothing abnormal occurs, the countdown 
proceeds to detonation. If a delay occurs, the 
appropriate preparatory meetings are repeated. 



^^In the case of tests sponsored by the Defense Nuclear Agency (DNA), the Scientific Advisor is from Sandia National Laboratory. 
2' Although the test has been planned to be contained, test preparations include provisions for an accidental release of radioactive material. Sue! 
provisions include the deployment of an emergency response team for each test. 

2*For example, readings from temperature sensors placed in the stemming plugs are examined to determine whether the plugs have hardened. 



Chapter 2 — The Nuclear Testing Program • 27 




Photo credit: Departmant of Energy 



Test Control Center 



Chapter 3 



Containing Underground 
Nuclear Explosions 



CONTENTS 

Page 

INTRODUCTION 31 

WHAT HAPPENS DURING AN UNDERGROUND NUCLEAR EXPLOSION 32 

Microseconds 32 

Milliseconds 32 

Tenths of a Second 32 

A Few Seconds 32 

Minutes to Days 32 

WHY NUCLEAR EXPLOSIONS REMAIN CONTAINED 34 

SELECTING LOCATION, DEPTH. AND SPACING: 35 

REVIEWING A TEST SITE LOCATION 37 

CONTAINMENT EVALUATION PANEL 38 

CONTAINING VERTICAL SHAFT TESTS 40 

CONTAINING HORIZONTAL TUNNEL TESTS 41 

TYPES OF RADIATION RELEASES 46 

Containment Failure: 46 

Late-Time Seep 46 

Controlled Tlinnel Purging 47 

Operational Release 47 

RECORD OF CONTAINMENT 47 

Containment Evaluation Panel 47 

Vertical Drill Hole Tests 48 

Horizontal Tlinnel Tests 48 

From the Perspective of Human Health Risk 49 

A FEW EXAMPLES: 49 

IS THERE A REAL ESTATE PROBLEM AT NTS? 51 

TIRED MOUNTAIN SYNDROME? 51 

HOW SAFE IS SAFE ENOUGH? 54 

Box 

Box Page 
3-A. Baneberry 33 

Figures 

Figure Page 

3-1. Formation of Stress "Containment Cage" 35 

3-2. Minimum Shot Separation for Drill Hole Tests 38 

3-3. Minimum Shot Separation for TUnnel Tests 39 

3-4. "Typical" Stemming Plan 41 

3-5. Three Redundant Containment Vessels 42 

3-6. Vessel I 43 

3-7. Vessel I Closures 44 

3-8. Tbnnel Closure Sequence 45 

3-9. Typical Post-Shot Configuration 46 

3-10. Radius of Decrease in Rock Strength 53 

Table 

Table Page 
3-1 . Release From Underground Tests 48 



Chapter 3 

Containing Underground Nuclear Explosions 



Underground nuclear tests are designed and reviewed for containment, with redundancy and 

conservatism in each step. 



INTRODUCTION 

The United States' first underground nuclear test, 
codenamed "Pascal- A," was detonated at the bot- 
tom of a 499-foot open drill-hole on July 26, 1957.' 
Although Pascal-A marked the beginning of under- 
ground testing, above ground testing continued for 
another 6 years. With testing simultaneously occur- 
ring aboveground, the release of radioactive material 
from underground explosions was at first not a major 
concern. Consequently, Pascal-A, like many of the 
early underground tests that were to follow, was 
conducted "roman candle" style in an open shaft 
that allowed venting. ^ 

As public sensitivity to fallout increased, guide- 
lines for testing in Nevada became more stringent. In 
1956, the weapons laboratories pursued efforts to 
reduce fallout by using the lowest possible test 
yields, by applying reduced fission yield or clean 
technology, and by containing explosions under- 
ground. Of these approaches, only underground 
testing offered hope for eliminating fallout. The 
objective was to contain the radioactive material, yet 
still collect all required information. The first 
experiment designed to contain an explosion com- 
pletely underground was the "Rainier" test, which 
was detonated on September 19, 1957. A nuclear 
device with a known yield of 1.7 kilotons was 
selected for the test. The test was designed with two 
objectives: 1) to prevent the release of radioactivity 
to the atmosphere, and 2) to determine whether 
diagnostic information could be obtained from an 
underground test. The test was successful in both 
objectives. Five more tests were conducted the 
following year to confirm the adequacy of such 
testing for nuclear weapons development. 

In November 1958, public concern over radioac- 
tive fallout brought about a nuclear testing morato- 
rium that lasted nearly 3 years. After the United 
States resumed testing in September, 1961, almost 
all testing in Nevada was done underground, while 



atmospheric testing was conducted in the Christmas 
Island and Johnston Island area of the Pacific. From 
1961 through 1963, many of the underground tests 
vented radioactive material. The amounts were 
small, however, in comparison to releases from 
aboveground testing also occurring at that time. 

With the success of the Rainier test, efforts were 
made to understand the basic phenomenology of 
contained underground explosions. Field efforts 
included tunneling into the radioactive zone, labora- 
tory measurements, and theoretical work to model 
the containment process. Through additional tests, 
experience was gained in tunnel-stemming proc- 
esses and the effects of changing yields. The early 
attempts to explain the physical reason why under- 
ground nuclear explosions do not always fracture 
rock to the surface did little more than postulate the 
hypothetical existence of a "mystical magical mem- 
brane." In fact, it took more than a decade of 
underground testing before theories for the physical 
basis for containment were developed. 

In 1963, U.S. atmospheric testing ended when the 
United States signed the Limited Test Ban Treaty 
prohibiting nuclear test explosions in any environ- 
ment other than underground. The treaty also 
prohibits any explosion that: 

. . . causes radioactive debris to be present outside 
the territorial limits of the State under whose 
jurisdiction or control such explosion is conducted.^ 

With the venting of radioactive debris from 
underground explosions restricted by treaty, con- 
tainment techniques improved. Although many U.S. 
tests continued to produce accidental releases of 
radioactive material, most releases were only detect- 
able within the boundaries of the Nevada Test Site. 
In 1970, however, a test codenamed "Baneberry" 
resulted in a prompt, massive venting. Radioactive 
material from Baneberry was tracked as far as the 
Canadian border and focused concern about both the 
environmental safety and the treaty compliance of 



'The firsl underground lest wa.s the United Stales' lOOth nuclear explosion. 

^It is interesting to note that even with an open shaft, 90% of the fission products created by Pascal-A were contained underground. 

^Article I, Kb). 1963 Limited Test Ban Treaty 



-31- 



32 • The Containment of Underground Nuclear Explosions 



the testing program.'* Testing was suspended for 7 
months while a detailed examination of testing 
practices was conducted by the Atomic Energy 
Commission. The examination resulted in new 
testing procedures and specific recommendations 
for review of test containment. The procedures 
initiated as a consequence of Baneberry are the basis 
of present-day testing practices. 

Today, safety is an overriding concern throughout 
every step in the planning and execution of an 
underground nuclear test. Underground nuclear test 
explosions are designed to be contained, reviewed 
for containment, and conducted to minimize even 
the most remote chance of an accidental release of 
radioactive material. Each step of the testing author- 
ization procedure is concerned with safety; and 
conservatism and redundancy are built into the 
system.-^ 

WHAT HAPPENS DURING AN 

UNDERGROUND NUCLEAR 

EXPLOSION 

The detonation of a nuclear explosion under- 
ground creates phenomena that occur within the 
following time fi^ames: 

Microseconds 

Within a microsecond (one-millionth of a sec- 
ond), the billions of atoms involved in a nuclear 
explosion release their energy. Pressures within the 
exploding nuclear weapon reach several million 
pounds per square inch; and temperatures are as high 
as 100 million degrees Centigrade. A strong shock 
wave is created by the explosion and moves outward 
from the point of detonation. 

Milliseconds 

Within tens of milliseconds (thousandths of a 
second), the metal canister and surrounding rock are 
vaporized, creating a bubble of high pressure steam 
and gas. A cavity is then formed both by the pressure 
of the gas bubble and by the explosive momentum 
imparted to the surrounding rock. 



Tenths of a Second 

As the cavity continues to expand, the intemal 
pressure decreases. Within a few tenths of a second, 
the pressure has dropped to a level roughly compara- 
ble to the weight of the overlying rock. At this point, 
the cavity has reached its largest size and can no 
longer grow.^ Meanwhile, the shock wave created by 
the explosion has traveled outward from the cavity, 
crushing and fracturing rock. Eventually, the shock 
wave weakens to the point where the rock is no 
longer crushed, but is merely compressed and then 
returns to its original state. This compression and 
relaxation phase becomes seismic waves that travel 
through the Earth in the same manner as seismic 
waves formed by an earthquake. 



A Few Seconds 

After a few seconds, the molten rock begins to 
collect and solidify in a puddle at the bottom of the 
cavity.^ Eventually, cooling causes the gas pressure 
within the cavity to decrease. 



Minutes to Days 

When the gas pressure in the cavity declines to the 
point where it is no longer able to support the 
overlying rock, the cavity may collapse. The col- 
lapse occurs as overlying rock breaks into rubble and 
falls into the cavity void. As the process continues, 
the void region moves upward as rubble falls 
downward. The "chimneying" continues until: 

• the void volume within the chimney completely 
fills with loose rubble. 

• the chimney reaches a level where the shape of 
the void region and the strength of the rock can 
support the overburden material, or 

• the chimney reaches the surface. 

If the chimney reaches the surface, the ground sinks 
forming a saucer-like subsidence crater. Cavity 
collapse and chimney formation typically occur 
within a few hours of the detonation but sometimes 
take days or months. 



■•See for example, Bruce A. Bolt, Nuclear Explosions and Earthquakes San Francisco, CA. (W.H. Freeman & Co., 1976). 
'See "Detonation Authority and Procedures" (ch. 2). 

*See the next section, "How explosions remain contained," for a detailed explanation of cavity formation. 

''The solidified rock contains most of the radioactive products from the explosion. The performance of the nuclear weapon is analyzed when samples 
of this material are recovered by drilling back into the cavity. 



Chapter 3 — Containing Underground Nuclear Explosions • 33 



Box 3-A — Baneberry 

The exact cause of the 1970 Banebeny venting still remains a mystery. The original explanation postulated 
the existence of an undetected water table. It assumed that the high temperatures of the explosion produced steam 
that vented to the surface. Later analysis, however, discredited this explanation and proposed an alternative scenario 
based on three geologic features of the Baneberry site: water-saturated clay, a buried scarp of hard rock, and a nearby 
fault. It is thought that the weak, water-saturated clay was unable to support the containment structure: the hard scarp 
strongly reflected back the energy of the explosion increasing its force; and the nearby fault provided a pathway 
that gases could travel along. All three of these features seem to have contributed to the venting. Whatever its cause, 
the Baneberry venting increased attention on containment and, in doing so, marked the beginning of the present-day 
containment practices. 










Photo credit: Department of Energy 



The venting of Baneberry. 1970. 



34 • The Containment of Underground Nuclear Explosions 




Photo credit Harold E. Edgerton 

Early phase of fireball from nuclear explosion. 

WHY NUCLEAR EXPLOSIONS 
REMAIN CONTAINED 

Radioactive material produced by a nuclear ex- 
plosion remains underground due to the combined 
efforts of: 

• the sealing nature of compressed rock around 
the cavity, 

• the porosity of the rock, 

• the depth of burial, 

• the strength of the rock, and 

• the stemming of the emplacement hole. 

Counter to intuition, only minimal rock 
strength is required for containment. 

At first, the explosion creates a pressurized cavity 
filled with gas that is mostly steam. As the cavity 
pushes outward, the surrounding rock is compressed 
(figure 3- 1(a)). Because there is essentially a fixed 
quantity of gas within the cavity, the pressure 
decreases as the cavity expands. Eventually the 
pressure drops below the level required to deform 
the surrounding material (figure 3-1 (b)). Mean- 
while, the shock wave has imparted outward motion 
to the material around the cavity. Once the shock 
wave has passed, however, the material tries to 



return (rebound) to its original position (figure 
3-1 (c)). The rebound creates a large compressive 
stress field, called a stress '"containment cage", 
around the cavity (figure 3- 1(d)). The physics of the 
stress containment cage is somewhat analogous to 
how stone archways support themselves. In the case 
of a stone archway, the weight of each stone pushes 
against the others and supports the archway. In the 
case of an underground explosion, the rebounded 
rock locks around the cavity forming a stress field 
that is stronger than the pressure inside the cavity. 
The stress "containment cage" closes any fractures 
that may have begun and prevents new fractures 
from forming. 

The predominantly steam-filled cavity eventually 
collapses forming a chimney. When collapse occurs, 
the steam in the cavity is condensed through contact 
with the cold rock falling into the cavity. The 
noncondensible gases remain within the lower 
chimney at low pressure. Once collapse occurs, 
high-pressure steam is no longer present to drive 
gases from the cavity region to the surface. 

If the test is conducted in porous material, such as 
alluvium or tuff, the porosity of the medium will 
provide volume to absorb gases produced by the 
explosion. For example, all of the steam generated 
by a 150 kiloton explosion beneath the water table 
can be contained in a condensed state within the 
volume of pore space that exists in a hemispherical 
pile of alluvium 200 to 300 feet high. Although most 
steam condenses before leaving the cavity region, 
the porosity helps to contain noncondensible gases 
such as carbon dioxide (COi) and hydrogen (H,). 
The gas diffuses into the interconnected pore space 
and the pressure is reduced to a level that is too low 
to drive the fractures. The deep water table and high 
porosity of rocks at the Nevada Test Site facilitate 
containment. 

Containment also occurs because of the pressure 
of overlying rock. The depth of burial provides a 
stress that limits fracture growth. For example, as a 
fracture initiated from the cavity grows, gas seeps 
from the fracture into the surrounding material. 
Eventually, the pressure within the fracture de- 
creases below what is needed to extend the fracture. 
At this point, growth of the fracture stops and the gas 
simply leaks into the surrounding material. 

Rock strength is also an important aspect of 
containment, but only in the sense that an extremely 
weak rock (such as water-saturated clay) cannot 



Chapter 3 — Containing Underground Nuclear Explosions • 35 



Figure 3-1— Formation of Stress "Containment Cage" 




Compressive residual stress 





1 ) Cavity expands outward and deforms surrounding rock. 2) Natural resistance to deformation stops expansion. 3) Cavity contracts 
(rebounds) from elastic unloading of distant rock. 4) Rebound locks in compressive residual stress around cavity. 

SOURCE: Modified from Lawrence Livermore National Laboratory 



support a stress containment cage. Detonation within 
weak, saturated clay is thought to have been a factor 
in the release of the Baneberry test. As a result, sites 
containing large amounts of water-saturated clay are 
now avoided. 

The final aspect of containment is the stemming 
that is put in a vertical hole after the nuclear device 
has been emplaced. Stemming is designed to prevent 
gas from traveling up the emplacement hole. Imper- 
meable plugs, located at various distances along the 
stemming column, force the gases into the surround- 
ing rock where it is "sponged up" in the pore spaces. 

How the various containment features perform 
depends on many variables: the size of the explo- 
sion, the depth of burial, the water content of the 
rock, the geologic structure, etc. Problems may 
occur when the containment cage does not form 
completely and gas from the cavity flows either 
through the emplacement hole or the overburden 
material.* When the cavity collapses, the steam 
condenses and only noncondensible gases such as 
carbon dioxide (COj) and hydrogen (Hj) remain in 
the cavity.^ The COj and H, remain in the chimney 
if there is available pore space. If the quantity of 
noncondensible gases is large, however, they can act 
as a driving force to transport radioactivity through 



the chimney or the overlying rock. Consequently, 
the amount of carbonate material and water in the 
rock near the explosion and the amount of iron 
available for reaction are considered when evaluat- 
ing containment."^ 

SELECTING LOCATION, DEPTH, 
AND SPACING 

The site for conducting a nuclear test is, at first, 
selected only on a tentative basis. The final decision 
is made after various site characteristics have been 
reviewed. The location, depth of burial, and spacing 
are based on the maximum expected yield for the 
nuclear device, the required geometry of the test, and 
the practical considerations of scheduling, conven- 
ience, and available holes. If none of the inventory 
holes are suitable, a site is selected and a hole 
drilled." 

The first scale for determining how deep an 
explosion should be buried was derived from the 
Rainier test in 1957. The depth, based on the cube 
root of the yield, was originally: 

Depth = 300 (yield) '^'• 

where depth was measured in feet and yield in 



*Lackof a stress "coniainment cage" may not be a serious problem if the medium is sufficently porous or if the deptli of burial is sufficent. 
'Ttie COt is formed from tlie vaporization of carbonate material; while the H, is formed when water reacts with the iron in the nuclear device and 
diagnostics equipment. 

"The carbonate material in Frenchman Rat created CO, that is thought to have caused a seep during the Diagonal Line test (Nov. 24, 1 97 1 ). Diagonal 
Line was the last test on Frenchman Flat; the area is currently considered impractical for underground testing largely because of the carbonate matenal. 
"See ch. 2, "The Nevada Test Site." for a description of the areas each Laboratory uses for testing. 



36 • The Containment of Underground Nuclear Explosions 




Photo credit Department ol Energy 



Blanca containment failure, 1958. 



kilotons. The first few tests after Rainier, however, 
were detonated at greater depths than this formula 
requires because it was more convenient to mine 
tunnels deeper in the Mesa. It was not until 
"Blanca," October 30, 1958, that a test was 
conducted exactly at 300 (yield) ^' feet to test the 
depth scale. The containment of the Blanca explo- 
sion, however, was unsuccessful and resulted in a 
surface venting of radioactive material. As a conse- 
quence, the depth scale was modified to include the 
addition of a few hundred feet as a safety factor and 



thus became: 300 (yield)'^^ 
feet." 



"plus-a-few-hundred- 



Today, the general depth of burial can be approxi- 
mated by the equation: 

Depth = 400 (yield)'-", 

where depth is measured in feet and yield in 
kilotons.'^ The minimum depth of burial, however, 
is 600 feet.'^ Consequently, depths of burial vary 
from 600 feet for a low-yield device, to about 2.1(X) 
feet for a large-yield test. The depth is scaled to the 



'^"Public Safely for Nuclear Weapons Tests," United Slates Envirorunenlal Protection Agency, January, 1984. 

"The 600-foot depth was chosen as a minimum after a statistical study showed that the lilscUhoodof a seep of radioactive material to the surface for 
explosions buried 600 feet or more was about 1/2 as great as for explosions at less than 5(X) feet, even if they were buried at the same scale-depth in 
each case. 



Chapter 3 — Containing Underground Nuclear Explosions • 37 



"maximum credible yield" that the nuclear device 
is thought physically capable of producing, not to 
the design yield or most likely yield.''* 

Whether a test will be conducted on Pahute Mesa 
or Yucca Flat depends on the maximum credible 
yield. Yucca Flat is closer to support facilities and 
therefore more convenient, while the deep water 
table at Pahute Mesa is more economical for large 
yield tests that need deep, large diameter emplace- 
ment holes. Large yield tests in small diameter holes 
(less than 7 feet) can be conducted in Yucca Flat. A 
test area may also be chosen to avoid scheduling 
conflicts that might result in a test damaging the hole 
or diagnostic equipment of another nearby test. Once 
the area has been chosen, several candidate sites are 
selected based on such features as: proximity to 
previous tests or existing drill holes; geologic 
features such as faults, depth to basement rock, and 
the presence of clays or carbonate materials; and 
practical considerations such as proximity to power 
lines, roads, etc. 

In areas well suited for testing, an additional site 
selection restriction is the proximity to previous 
tests. For vertical drill hole tests, the minimum shot 
separation distance is about one-half the depth of 
burial for the new shot (figure 3-2). For shallow 
shots, this separation distance allows tests to be 
spaced so close together that in some cases, the 
surface collapse craters coalesce. The V2 depth of 
burial distance is a convention of convenience, 
rather than a criteron for containment.'"' It is, for 
example, difficult to safely place a drilling rig too 
close to an existing collapse crater. 

Horizontal tunnel tests are generally spaced with 
a minimum shot separation distance of twice the 
combined cavity radius plus ICX) feet, measured 
from the point of detonation (called the "working 
point") (figure 3-3). In other words, two tests with 
100 foot radius cavities would be separated by 300 
feet between cavities, or 500 feet (center to center). 
The size of a cavity formed by an explosion is 
proportional to the cube root of the yield and can be 
estimated by: 

Radius = 55 (yield) '^^ 

where the radius is measured in feet and the yield in 



kilotons. For example, an 8 kiloton explosion would 
be expected to produce an underground cavity with 
approximately a 110 foot radius. Two such test 
explosions would require a minimum separation 
distance of 320 feet between cavities or 540 feet 
between working points. 

Occasionally, a hole or tunnel is found to be 
unsuitable for the proposed test. Such a situation, 
however, is rare, occurring at a rate of about 1 out of 
25 for a drill hole test and about 1 out of 15 for a 
tunnel test.'^ Usually, a particular hole that is found 
unacceptable for one test can be used for another test 
at a lower yield. 

REVIEWING A TEST SITE 
LOCATION 

Once the general parameters for a drill-hole have 
been selected, the sponsoring laboratory requests a 
pre-drill Geologic Data Summary (CDS) from the 
U.S. Geological Survey. The GDS is a geologic 
interpretation of the area that reviews the three basic 
elements: the structures, the rock type, and the water 
content. The U.S. Geological Survey looks for 
features that have caused containment problems in 
the past. Of particular concern is the presence of any 
faults that might become pathways for the release of 
radioactive material, and the close location of hard 
basement rock that may reflect the energy created by 
the explosion. Review of the rock type checks for 
features such as clay content which would indicate 
a weak area where it may be difficult for the hole to 
remain intact, and the presence of carbonate rock 
that could produce COj. Water content is also 
reviewed to predict the amount of steam and Hj that 
might be produced. If the geology indicates less than 
ideal conditions, alternate locations may be sug- 
gested that vary from less than a few hundred feet 
from the proposed site to an entirely different area of 
the test site. 

When the final site location is drilled, data are 
collected and evaluated by the sponsoring labora- 
tory. Samples and geophysical logs, including down- 
hole photography, are collected and analyzed. The 
U.S. Geological Survey reviews the data, consults 
with the laboratory throughout the process, and 
reviews the accuracy of the geologic interpretations. 



'"•In many cases the maximum credible yield is significantly larger than the expected yield for a nuclear device. 
"As discussed later, testing in previously fractured rock is not considered a containment risk in most instances. 
'*On three occasions tunnels have been abandoned because of unanticipated conditions such as the discovery of a fault or the presence of too much 



38 • The Containment of Underground Nuclear Explosions 



Figure 3-2 — Minimum Shot Separation for Driil Hole Tests 

Vi depth of burial 




Diagram to approximate scale 

Scale Illustration of tfie minimum separation distance (1/2 depth of burial) for vertical drill fiole tests. Tfie 
deptli of burial is based on the maximum credible yield. 

SOURCE: Office of Tectinology Assessment. 1989 



To confirm the accuracy of the geologic description 
and review and evaluate containment considera- 
tions, the Survey also attends the host laboratory's 
site proposal presentation to the Containment Evalu- 
ation Panel. 

CONTAINMENT EVALUATION 
PANEL 

One consequence of the Baneberry review was the 
restructuring of what was then called the Test 
Evaluation Panel. The panel was reorganized and 
new members with a wider range of geologic and 
hydrologic expertise were added. The new panel was 
named the Containment Evaluation Panel (CEP); 
and their first meeting was held in March, 1971. 

The Containment Evaluation Panel presently 
consists of a Chairman and up to 1 1 panel members. 



Six of the panel members are representatives from 
Lawrence Livermore National Laboratory, Los Alamos 
National Laboratory, Defense Nuclear Agency, San- 
dia National Laboratory, U.S. Geological Survey, 
and the Desert Research Institute. An additional 3 to 
5 members are also included for their expertise in 
disciplines related to containment. The chairman of 
the panel is appointed by the Manager of Nevada 
Operations (Department of Energy), and panel 
members are nominated by the member institution 
with the concurrence of the chairman and approval 
of the Manager. The panel reports to the Manager of 
Nevada Operations. 

Practices of the Containment Evaluation Panel 
have evolved throughout the past 1 8 years; however, 
their purpose, as described by the Containment 



Chapter 3 — Containing Underground Nuclear Explosions • 39 



Figure 3-3— Minimum Shot Separation for Tunnei Tests 



Tunnel tests are typically 
overburied. Collapse ctiimneys 
do not usually extend to surface. 




Diagram to approxinnate scale 



Scale illustration of the minimum separation distance (2 combined cavity radii plus 100 feet) for 
horizontal tunnel tests. Tunnel tests are typically overburied. Collapse chimneys do not usually extend 
to the surface. 

SOURCE: Office of Technology Assessment. 1989 



Evaluation Charter, remains specifically defined as 
follows:'^ 

1. evaluate, as an independent organization re- 
porting to the Manager of Nevada Operations, 
the containment design of each proposed 
nuclear test; 

2. assure that all relevant data available for 
proper evaluation are considered; 

3. advise the manager of Nevada Operations of 
the technical adequacy of such design from the 
viewpoint of containment, thus providing the 
manager a basis on which to request detona- 
tion authority; and 



4. maintain a historical record of each evaluation 
and of the data, proceedings, and discussions 
pertaining thereto. 

Although the CEP is charged with rendering a 
judgment as to the adequacy of the design of the 
containment, the panel does not vote. Each member 
provides his independent judgment as to the pros- 
pect of containment, usually addressing his own area 
of expertise but free to comment on any aspect of the 
test. The Chairman is in charge of summarizing 
these statements in a recommendation to the man- 
ager on whether to proceed with the lest, based only 
on the containment aspects. Containment Evalua- 
tion Panel guidelines instruct members to make their 
judgments in such a way that: 



"Containment Evaluation Charter, June 1, 1986, Section II. 



40 • The Containment of Underground Nuclear Explosions 



Considerations of cost, schedules, and test objectives 
shall not enter into the review of the technical 
adequacy of any test from the viewpoint of contain- 
ment.'* 

Along with their judgments on containment, each 
panel member evaluates the probability of contain- 
ment using the following four categories:'^ 

1. Category A: Considering all containment fea- 
tures and appropriate historical, empirical, and 
analytical data, the best judgment of the 
member indicates a high confidence in suc- 
cessful containment as defined in VIII. F. 
below. 

2. Category B: Considering all containment fea- 
tures and appropriate historical, empirical, and 
analytical data, the best judgment of the 
member indicates a less, but still adequate, 
degree of confidence in successful contain- 
ment as defined in VIII. F. below. 

3. Category C: Considering all containment fea- 
tures and appropriate historical, empirical, and 
analytical data, the best judgment of the 
member indicates some doubt that successful 
containment, as described in VIII.F. below, 
will be achieved. 

4. Unable to Categorize 

Successful containment is defined for the CEP as: 

... no radioactivity detectable off-site as measured 
by normal monitoring equipment and no unantici- 
pated release of activity on-site. 

The Containment Evaluation Panel does not have 
the direct authority to prevent a test from being 
conducted. Their judgment, both as individuals and 
as suinmarized by the Chairman, is presented to the 
Manager. The Manager makes the decision as to 
whether a Detonation Authority Request will be 
made. The statements and categorization from each 
CEP member are included as part of the permanent 
Detonation Authority Request. 

Although the panel only advises the Manager, it 
would be unlikely for the Manager to request 



detonation if the request included a judgment by the 
CEP that the explosion might not be contained. The 
record indicates the influence of the CEP. Since 
formation of the panel in 1970, there has never been 
a Detonation Authority Request submitted for ap- 
proval with a containment plan that received a "C" 
("some doubt") categorization from even one 
member. ^'^-' 

The Containment Evaluation Panel serves ar. 
additional role in improving containment as a 
consequence of their meetings. The discussions of 
the CEP provide an ongoing forum for technical 
discussions of containment concepts and practices. 
As a consequence, general improvements to contain- 
ment design have evolved through the panel discus- 
sions and debate. 



CONTAINING VERTICAL 
SHAFT TESTS 

Once a hole has been selected and reviewed, a 
stemming plan is made for the individual hole. The 
stemming plan is usually formulated by adapting 
previously successful stemming plans to the particu- 
larities of a given hole. The objective of the plan is 
to prevent the emplacement hole from being the path 
of least resistance for the flow of radioactive 
material. In doing so, the stemming plan must take 
into account the possibility of only a partial collapse: 
if the chimney collapse extends only half way to the 
surface, the stemming above the collapse must 
remain intact. 

Lowering the nuclear device with the diagnostics 
down the emplacement hole can take up to 5 days. 
A typical test will have between 50 and 250 
diagnostic cables with diameters as great as P/s 
inches packaged in bundles through the stemming 
column. After the nuclear device is lowered into the 
emplacement hole, the stemming is installed. Figure 
3-4 shows a typical stemming plan for a Lawrence 



"Containment Evaluation Panel Charter. June 1. 1986. Section HID. 

"Containment Evaluation Panel Charter, June 1, 1986, Section VII. 

^'The grading system for containment plans has evolved since the early 1970's. Prior to April, 1977, the Containment Evaluation Panel categorized 
tests using the Roman numerals (I-IV) where I-lII had about the same meaning as A-C and IV was a D which eveniually was dropped as a letter and 
just became "unable to categorize." 

^'However, one shot (Mundo) was submitted with an "unable to categorize" categorization. Mundo was a joint US-UK test conducted on May 1. 
1984. 



Chapters — Containing Underground Nuclear Explosions •41 



Figure 3-4— "Typical" Stemming Plan 




Cable gas blocks 



(Diagram not to scale) 



Typical stemming sequence of coarse material, fine material, and 
sanded gypsum plug used by Lawrence LIvermore National 
Laboratory for vertical drill hole tests. 

SOURCE: Modified from Lawrence Livermore National Laboratory 



Livermore test with six sanded gypsum concrete 
plugs. ■^■^ The plugs have two purposes: 1) to impede 
gas flow, and 2) to serve as structural platforms that 
prevent the stemming from falling out if only a 
partial collapse occurs. Under each plug is a layer of 
sand-size fine material. The sand provides a base for 
the plug. Alternating between the plugs and the 
fines, coarse gravel is used to fill in the rest of the 
stemming. The typical repeating pattern used for 
stemming by Los ALamos, for example, is 50 feet of 
gravel, 1 feet of sand, and a plug. 

All the diagnostic cables from the nuclear device 
are blocked to prevent gas from finding a pathway 
through the cables and traveling to the surface. Cable 
fan-out zones physically separate the cables at plugs 



so that the grout and fines can seal between them. 
Frequently, radiation detectors are installed between 
plugs to monitor the post-shot flow of radiation 
through the stemming column. 

CONTAINING HORIZONTAL 
TUNNEL TESTS 

The containment of a horizontal tunnel test is 
different from the containment of a vertical drill hole 
test because the experimental apparatus is intended 
to be recovered. In most tests, the objective is to 
allow direct radiation from a nuclear explosion to 
reach the experiment, but prevent the explosive 
debris and fission products from destroying it. 
Therefore, the containment is designed for two 
tasks: 1) to prevent the uncontrolled release of 
radioactive material into the atmosphere for public 
safety, and 2) to prevent explosive debris from 
reaching the experimental test chamber. 

Both types of horizontal tunnel tests (effects tests 
and cavity tests) use the same containment concept 
of three redundant containment "vessels" that nest 
inside each other and are separated by plugs (figure 
3-5).^^ Each vessel is designed to independently 
contain the nuclear explosion, even if the other 
vessels fail. If, for example, gas leaks from vessel I 
into vessel II, vessel II has a volume large enough so 
that the resulting gas temperatures and pressures 
would be well within the limits that the plugs are 
designed to withstand. The vessels are organized as 
follows: 

Vessel I is designed to protect the experiment by 
preventing damage to the equipment and allowing it 
to be recovered. 

Vessel II is designed to protect the tunnel system 
so that it can be reused even if vessel I fails and the 
experimental equipment is lost. 

Vessel III is designed purely for containment, 
such that even if the experimental equipment is lost 
and the tunnel system contaminated, radioactive 
material will not escape to the atmosphere. 

In addition to the three containment vessels, there 
is a gas seal door at the entrance of the tunnel system 
that serves as an additional safety measure. The gas 
seal door is closed prior to detonation and the area 



^^Allhough Livermore and Ixis Alamos use the same general stemming philosophy, there are some differences: For example, Livermore uses sanded 
gypsum concrete plugs while Los Alamos uses plugs made of epoxy. Also, Livermore uses an emplacement pipe for lowering the device downhole. while 
IjOs Alamos lowers the device and diagnostic cannister on a wire rope harness. 

^^See ch. 2 for a discussion of types of nuclear tests. 



42 • The Containment of Underground Nuclear Explosions 



Figure 3-5 — Three Redundant Containment Vessels (Plan View) 



Tunnel 



entrance 



Ca^i^V 



\y 




Three containment vessels tor the Migtity Oak Test conducted in ttie T-Tunnel Complex. 
SOURCE: Modified from Defense Nuclear Agency. 



between it and the vessel III plug is pressuiized to 
approximately 10 pounds per square inch. 

The plugs that separate the vessels are constructed 
of high strength grout or concrete 10 to 30 feet thick. 
The sides of the vessel II plugs facing the working 
point are constructed of steel. Vessel II plugs are 
designed to withstand pressures up to 1 .000 pounds 
per square inch and temperatures up to 1,000 °F. 
Vessel III plugs are constructed of massive concrete 
and are designed to withstand pressures up to 500 
pounds per square inch and temperatures up to 500 
T. 

Before each test, the tunnel system is checked for 
leaks. The entire system is closed off and pressurized 
to 2 pounds per square inch with a gas containing 
tracers in it. The surrounding area is then monitored 



for the presence of the tracer gas. Frequently, the 
chimney formed by the explosion is also subjected 
to a post-shot pressurization test to ensure that no 
radioactive material could leak through the chimney 
to the surface. 

The structure of vessel I. as shown in figure 3-6, 
is designed to withstand the effects of ground shock 
and contain the pressure, temperatures, and radiation 
of the explosion. The nuclear explosive is located at 
the working point, also known as the "zero room." 
A long, tapered, horizontal line-of-sight (HLOS) 
pipe extends 1 ,000 feet or more from the working 
point to the test chamber where the experimental 
equipment is located. The diameter of the pipe may 
only be a few inches at the working point, but 
typically increases to about 10 feet before it reaches 



Chapter S — Containing Underground Nuclear Explosions • 43 



Figure 3-6— Vessel I 



End of stemming 

^ '^ 




Test ctiamber 
End of stemming 



Key: GSAC =gas seal auxiliary closure; MAC = modified auxiliary 
closure; TAPS = Tunnel and pipe seal 

The HLOS Vessel I is designed to protect tfie experimental 
equipment after allowing radiation to travel down the pipe. 

SOURCE; Modified from Defense Nuclear Agency 

the test chamber. ^'^ The entire pipe is vacuum 
pumped to simulate the conditions of space and to 
minimize the attenuation of radiation. The bypass 
drift (an access tunnel), located next to the line of 
sight pipe, is created to provide access to the closures 
and to different parts of the tunnel system. These 
drifts allow for the nuclear device to be placed in the 
zero room and for late-time emplacement of test 
equipment. After the device has been emplaced at 
the working point, the bypass drift is completely 
filled with grout. After the experiment, parts of the 
bypass drift will be reexcavated to permit access to 
the tunnel system to recover the pipe and experimen- 
tal equipment. 

The area around the HLOS pipe is also filled with 
grout, leaving only the HLOS pipe as a clear 
pathway between the explosion and the test cham- 
ber. Near the explosion, grout with properties similar 
to the surrounding rock is used so as not to interfere 
with the formation of the stress containment cage. 
Near the end of the pipe strong grout or concrete is 
used to support the pipe and closures. In between, 
the stemming is filled with super-lean grout de- 
signed to flow under moderate stress. The super-lean 
grout is designed to fill in and effectively plug any 
fractures that may form as the ground shock 
collapses the pipe and creates a stemming plug. 

As illustrated in figure 3-6, the principal compo- 
nents of an HLOS pipe system include a working 



point room, a muffler, a modified auxiliary closure 
(MAC), a gas seal auxiliary closure (GSAC), and a 
tunnel and pipe seal (TAPS). All these closures are 
installed primarily to protect the experimental equip- 
ment. The closures are designed to shut off the pipe 
after the radiation created by the explosion has 
traveled down to the test chamber, but before 
material from the blast can fly down the pipe and 
destroy the equipment. 

The working point room is a box designed to 
house the nuclear device. The muffler is an ex- 
panded region of the HLOS pipe that is designed to 
reduce flow down the pipe by allowing expansion 
and creating turbulence and stagnation. The MAC 
(figure 3-7(a)) is a heavy steel housing that contains 
two 12-inch-thick forged-aluminum doors designed 
to close openings up to 84 inches in diameter. The 
doors are installed opposite each other, perpendicu- 
lar to the pipe. The doors are shut by high pressure 
gas that is triggered at the time of detonation. 
Although the doors close completely within 0.03 
seconds (overlapping so that each door fills the 
tunnel), in half that time they have met in the middle 
and obscure the pipe. The GSAC is similar to the 
MAC except that it is designed to provide a gas-tight 
closure. The TAPS closure weighs 40 tons and the 
design (figure 3-7(b)) resembles a large toilet seat. 
The door, which weighs up to 9 tons, is hinged on the 
top edge and held in the horizontal (open) position. 
When the door is released, it swings down by gravity 
and slams shut in about 0.75 seconds. Any pressure 
remaining in the pipe pushes on the door making the 
seal tighter. The MAC and GSAC will withstand 
pressures up to 10,000 pounds per square inch. The 
TAPS is designed to withstand pressures up to 1 .000 
pounds per square inch, and temperatures up to 
1,000 T. 

When the explosion is detonated radiation travels 
down the HLOS pipe at the speed of light. The 
containment process (figure 3-8(a-e), triggered at the 
time of detonation, occurs in the following sequence 
to protect experimental equipment and contain 
radioactive material produced by the explosion: 

• After 0.03 seconds (b), the cavity created by the 
explosion expands and the shock wave moves 
away from the working point and approaches 
the MAC. The shock wave collapses the pipe, 
squeezing it shut, and forms a stemming 
"plug." Both the MAC and the GSAC shut off 



^■•On occasion, the diameter of the pipe has increased lo 20 feet. 



44 • The Containment of Underground Nuclear Explosions 



Figure 3-7— Vessel I Closures 




■ Mechanical closures 
(MAC/GSAC) 



Mechanical closure 
(TAPS) 





Pre-fire geometry 



Approximate closed FAC geometry 



Fast acting closure 
(FAC) 



A) Mechanical Closures (MAC/GSAC) 

B) Tunnel and Pipe Seal (TAPS) 

C) Fast Acting Closure (FAC) 

SOURCE: Modified from Defense Nuclear Agency. 



the pipe ahead of the shock wave to prevent 
early flow of high-velocity gas and debris into 
the experiment chamber. 

• After 0.05 seconds (c), the ground shock moves 
past the second closure and is no longer strong 



enough to squeeze the pipe shut. The stemming 
plug stops forming at about the distance where 
the first mechanical pipe closure is located. 

After 0.2 seconds (d), the cavity growth is 
complete. The rebound from the explosion 



Chapter 3 — Containing Underground Nuclear Explosions • 45 



A Zero 
lime 



Figure 3-8 — Tunnel Closure Sequence 

D i 



Working point Mulller 



Ground 
shock 

Stemnning ^i\ 
plug " 



I 

LOS pipe 
Mechanical closure(TAPS) 
Mechanical closure(GSAC| 
Mechanical closure(MACl 





Mechanical closure! TAPS) 
Mechanical closure(GSAC) 
Mechanical closure(MAC) 



Test channber 
End of stemming 



^sE^Mh 



End of stemming 




Mechanical closure(TAPS| | Test chamber 

Mechanical closure(GSAC) End of stemming 

'#/ 

Mechanical closure(MAC) 



Mechanical closure(TAPS) I Test chamber 

Mechanical closure(GSAC) End of stemming 

Mechanical closure(MAC) 




75 
seconds 



Mechanical closure(TAPS) 
Mechanical closure(GSAC) 
Mechanical closure(MAC) 




Test chamber 
End of stemming 



A) Zero Time: Explosion is detonated and the first two mechanical closures are fired. B) Within 0.03 seconds, a stemming plug is being 
formed and mechanical pipe closure has occurred. C) Within 0.05 seconds, the stemming plug has formed. D) Within 0.2 seconds, cavity 
growth is complete and a surrounding compressive residual stress field has formed. E) Within 0.75 seconds, closure is complete. 

SOURCE: Modified from Defense Nuclear Agency. 



46 • The Containment of Underground Nuclear Explosions 



locks in the residual stress field, thereby 
forming a containment cage. The shock wave 
passes the test chamber. 

• After 0.75 seconds (e). the final mechanical seal 
(TAPS) closes, preventing late-time explosive 
and radioactive gases from entering the test 
chamber. 

The entire closure process for containment takes 
less than ^A of a second. Because the tests are 
typically buried at a depth greater than necessary for 
containment, the chimney does not reach the surface 
and a collapse crater normally does not form. A 
typical post-shot chimney configuration with its 
approximate boundaries is shown in figure 3-9. 

In lower yield tests, such as those conducted in the 
P-tunnel complex, the first mechanical closure is a 
Fast Acting Closure (FAC) rather than a MAC.^^ 
The FAC (figure 3-7(c)) closes in 0.001 seconds and 
can withstand pressures of 30,000 pounds per square 
inch. The FAC acts like a cork, blocking off the 
HLOS pipe early, and preventing debris and stem- 
ming material from flying down the pipe. A similar 
closure is currently being developed for larger yield 
tunnel tests. 

TYPES OF RADIATION RELEASES 

Terms describing the release or containment of 
underground nuclear explosions have been refined 
to account for the volume of the material and the 
conditions of the release. The commonly used terms 
are described below. 

Containment Failure 

Containment failures are releases of radioactive 
material that do not fall within the strict definition of 
successful containment, which is described by the 
Department of Energy as: 

Containment such that a test results in no radioac- 
tivity detectable off site as measured by normal 
monitoring equipment and no unanticipated release 
of radioactivity onsite. Detection of noble gases that 
apjiear onsite long after an event, due to changing 
atmospheric conditions, is not unanticipated. Antici- 
pated releases will be designed to conform to 
specific guidance from DOE/HQ.^*' 

Containment failures are commonly described as: 



Figure 3-9— Typical Post-Shot Configuration 




Tunnel 
complex 



Tunnel shots are typically overburied and the collapse chimney 
rarely extends to the surface. 

SOURCE: Modified from Defense Nuclear Agency. 



Ventings 

Ventings are prompt, massive, uncontrolled re- 
leases of radioactive material. They are character- 
ized as active releases under pressure, such as when 
radioactive material is driven out of the ground by 
steam or gas. "Baneberry," in 1970, is the last 
example of an explosion that "vented." 

Seeps 

Seeps, which are not visible, can only be detected 
by measuring for radiation. Seeps are characterized 
as uncontrolled slow releases of radioactive material 
with little or no energy. 



Late-Time Seep 

Late-time seeps are small releases of nonconden- 
sable gases that usually occur days or weeks after a 
vertical drill hole test. The noncondensable gases 
diffuse up through the pore spaces of the overlying 
rock and are thought to be drawn to the surface by a 
decrease in atmospheric pressure (called "atmos- 
pheric pumping"). 



^-''The P-iunnel complex is mined in Aqueducl Mesa and has less overburden than the N-tunnel complex in Rainier Mesa. Therefore, P-lunnel is 
generally used for lower yield tests. 

^Section VIII. F, Containment Evaluation Panel Charter. 



Chapters — Containing Underground Nuclear Explosions •47 




Photo credit: David Graham 



Fast acting closure. 



Controlled Tunnel Purging 

Controlled tunnel purging is an intentional release 
of radioactive material to recover experimental 
equipment and ventilate test tunnels. During a 
controlled tunnel purging, gases from the tunnel are 
filtered, mixed with air to reduce the concentration, 
and released over time when weather conditions are 
favorable for dispersion into sparsely populated 
areas. 

Operational Release 

Operational releases are small releases of radioac- 
tivity resulting from operational aspects of vertical 
drill hole tests. Activities that often result in 
operational releases include: drilling back down to 
the location of the explosion to collect core samples 
(called "drill back"), collecting gas samples from 



the explosion (called "gas sampling"), and sealing 
the drill back holes (called "cement back") 

RECORD OF CONTAINMENT 

The containment of underground nuclear explo- 
sions is a process that has continually evolved 
through learning, experimentation, and experience. 
The record of containment illustrates the various 
types of releases and their relative impact. 

Containment Evaluation Panel 

The Containment Evaluation Panel defines suc- 
cessful containment as no radioactivity detectable 
offsite and no unanticipated release of activity 
ensile. By this definition, the CEP has failed to 
predict unsuccessful containment on four occasions 
since 1970: 



48 • The Containment of Underground Nuclear Explosions 



Camphor: June 29, 1971, horizontal tunnel test, 

less than 20 kilotons, radioactivity de- 
tected only on-site. 

Diagonal Line: Novemt)er 24, 1971, vertical shaft test, 
less than 20 kilotons, radioactivity de- 
tected off-site. 

Riola: September 25, 1980, vertical shaft test, 

less than 20 kilotons, radioactivity de- 
tected off-site. 

Agrini: March 31, 1984, vertical shaft test, less 

than 20 kilotons, radioactivity detected 
only on-site. 

These are the only tests (out of more than 200) 
where radioactive material has been unintentionally 
released to the atmosphere due to containment 
failure. In only two of the cases was the radioactivity 
detected outside the geographic boundary of the 
Nevada Test Site. 

There have, however, been several other instances 
where conditions developed that were not expected. 
For example, during the Midas Myth test on 
February 15, 1984, an unexpected collapse crater 
occurred above the test tunnel causing injuries to 
personnel. In addition, the tunnel partially collapsed, 
damaging experimental equipment. During the Mighty 
Oak test on April 10, 1986, radioactive material 
penetrated through two of the three containment 
vessels. Experimental equipment worth $32 million 
was destroyed and the tunnel system ventilation 
required a large controlled release of radioactive 
material (table 3-1). In the case of Midas Myth, no 
radioactive material was released (in fact, all radio- 
active material was contained within vessel I). In the 
case of Mighty Oak, the release of radioactive 
material was intentional and controlled. Conse- 
quently, neither of these tests are considered con- 
tainment failures by the CEP. 

Vertical Drill Hole Tests 

As discussed previously, vertical drill-hole tests 
commonly use a stemming plan with six sanded 
gypsum plugs or three epoxy plugs. Approximately 
50 percent of the vertical drill hole tests show all 
radiation being contained below the first plug. In 
some cases, radiation above the plug may not signify 
plug failure, but rather may indicate that radioactive 
material has traveled through the medium around the 
plug- 



Table 3-1— Releases From Underground Tests 
(normalized to 12 hours after event*) 

All releases 1971-1988: 

Containment Failures: 

Camphor, 1971" 360 Ci 

Diagonal Line, 1971 6,800 

Riola, 1980 3,100 

Agrini, 1 984 690 

Late-time Seeps: 

Kappeli, 1984 12 

Tierra, 1984 600 

Labquark, 1986 20 

Bodie, 1986^ 52 

Controlled Tunnel Purgings: 

Hybia Fair, 1974 500 

Hybia Gold, 1977 0.005 

Miners Iron, 1 980 0.3 

Huron Landing, 1 982 280 

Mini Jade, 1 983 1 

Mill Yard, 1985 5.9 

Diamond Beech, 1985 1.1 

Misty Rain, 1 985 63 

Mighty Oak, 1986 36,000 

Mission Ghost, 1987<= 3 

Operational Releases: 

108 tests from 1970-1988" 5,500 

Total since Baneberry: 54,000 Ci 
Major pre- 1971 releases: 

Platte, 1962 1,900,000 Ci 

Eel, 1962 1,900,000 

Des Moines, 1962 11,000,000 

Baneberry, 1970 6,700,000 

26 others from 1958-1970 3,800,000 

Total: 25,300,000 Ci 
Other Releases for Reference 

NTS Atmospheric Testing 1951-1963: . . 12,000,000,000 Ci 

1 Kiloton Aboveground Explosion: 10,000,000 

Chernobyl (estimate): 81 ,000,000 

3R+12 values apply only to containment failures, others are at time of 

release 
''The Camphor failure includes 140 Ci from tunnel purging, 
'^Bodie and Mission Ghost also had drill-back releases. 
•^Many of these operational releases are associated with tests that were not 
announced 
SOURCE: Office of Technology Assessment, 1989. 



All three of the vertical drill hole tests that 
released radioactive material through containment 
failure were low yield tests of less than 20 kilotons. 
In general, the higher the yield, the less chance there 
is that a vertical drill hole test will release radioactiv- 
ity.27 

Horizontal Tunnel Tests 

There have been no uncontrolled releases of 
radioactive material detected offsite in the 3 1 tunnel 
tests conducted since 1970. Furthermore, all but one 
test, Mighty Oak, have allowed successful recovery 



"Higher yield tests arc more likely to produce a containment cage and result in the formation of a collapse crater. As discussed earlier in this chapter 
"why nuclear explosions remain contained," such features contribute to the containment of the explosion. 



Chapter 3 — Containinii; Underground Nuclear Explosions • 49 



of the experimental equipment. Mighty Oak and 
Camphor are the only tests where radioactivity 
escaped out of vessel II. In no test, other than 
Camphor, has radioactive material escaped out of 
vessel III. Camphor resulted in an uncontrolled 
release of radioactive material that was detected 
only on site. 

There have been several instances when small 
amounts of radioactivity were released intentionally 
to the atmosphere through controlled purging. In 
these cases, the decision was made to vent the tunnel 
and release the radioactivity so the experimental 
results and equipment could be recovered. The 
events that required such a controlled release are the 
10 tests where radioactive material escaped out of 
vessel I and into vessel II, namely: 

Hybla Fair, October 28, 1974. 

Hybia Gold, November 1, 1977. 

Miners Iron, October 31, 1980. 

Huron Landing, September 23, 1982. 

Mini Jade, May 26, 1983. 

Mill Yard, October 9, 1985. 

Diamond Beech, October 9, 1985. 

Misty Rain, April 6, 1985. 

Mighty Oak, April 10, 1986. 

Mission Ghost, June 20, 19872« 

In most cases, the release was due to the failure of 
some part of the experiment protection system. 

Table 3-1 includes every instance (for both 
announced and unannounced tests) where radioac- 
tive material has reached the atmosphere under any 
circumstances whatsoever from 1971 through 1988. 
The lower part of table 3-1 summarizes underground 
tests prior to 1971 and provides a comparison with 
other releases of radioactive material. 

Since 1970, 126 tests have resulted in radioactive 
material reaching the atmosphere with a total release 
of about 54,000 Curies(Ci). Of this amount, 1 1 ,500 
Ci were due to containment failure and late-time 
seeps. The remaining 42,500 Ci were operational 
releases and controlled tunnel ventilations — with 
Mighty Oak (36,000 Ci) as the main source. Section 



3 of the table shows that the release of radioactive 
material from underground nuclear testing since 
Baneberry (54,000 Ci) is extremely small in compar- 
ison to the amount of material released by pre- 
Baneberry underground tests (25,300,000 Ci), the 
early atmospheric tests at the Nevada Test Site, or 
even the amount that would be released by a 
1 -kilolon explosion conducted above ground ( 1 0,000,(X)0 
Ci). 

From the Perspective of Human Health Risk 

If a single person had been standing at the 
boundary of the Nevada Test Site in the area of 
maximum concentration of radioactivity for every 
test since Baneberry (1970), that person's total 
exposure would be equivalent to 32 extra minutes 
of normal background exposure (or the equiva- 
lent of 1/1000 of a single chest x-ray). 

A FEW EXAMPLES: 

Although over 90 percent of all test explosions 
occur as predicted, occasionally something goes 
wrong. In some cases, the failure results in the loss 
of experimental equipment or requires the controlled 
ventilation of a tunnel system. In even more rare 
cases (less than 3 percent), the failure results in the 
unintentional release of radioactive material to the 
atmosphere. A look at examples shows situations 
where an unexpected sequence of events contribute 
to create an unpredicted situation (as occurred in 
Baneberry (see box 3-1)), and also situations where 
the full reason for containment failure still remains 
a mystery. 

1 . Camphor (June 29, 1971 , horizontal tunnel test, 
less than 20 kilotons, radioactivity detected only 
on-site.) 

The ground shock produced by the Camphor 
explosion failed to close the HLOS pipe fully. After 
about 10 seconds, gases leaked through and eroded 
the stemming plug. As gases flowed through the 
stemming plug, pressure increased on the closure 
door behind the experiment. Gases leaked around 
the cable passage ways and eroded open a hole. 
Pressure was then placed on the final door, which 
held but leaked slightly. Prior to the test, the 
containment plan for Camphor received six "I"s 
from the CEP.^'* 



^*The Mission Ghost release was due lo a posl-shot drill hole. 
290p. cit.. footnote 20. 



50 • The Containment of Underground Nuclear Explosions 



2. Diagonal Line (November 24, 1971, vertical 
shaft test, less than 20 kilotons, radioactivity de- 
tected off-site.) 

In a sense, the Diagonal Line seep was predicted 
by the CEP. Prior to the test. Diagonal Line received 
all "A" categorizations, except from one member 
who gave it a "B."^'' It was a conclusion of the panel 
that due to the high CO, content, a late-time (hours 
or days after detonation) seepage was a high 
probability. They did not believe, however, that the 
level of radiation would be high enough to be 
detectable off-site. Permission to detonate was 
requested and granted because the test objectives 
were judged to outweigh the risk. Diagonal Line was 
conducted in the northern part of Frenchman Flat. It 
is speculated that carbonate material released COj 
gas that forced radioactive material to leak to the 
surface. Diagonal Line was the last test detonated on 
Frenchman Flat. 

3. Riola (September 25, 1980, vertical shaft test, 
less than 20 kilotons, radioactivity detected off-site.) 

Ironically, Riola was originally proposed for a 
different location. The Containment Evaluation 
Panel, however, did not approve the first location 
and so the test was moved. At its new location, Riola 
was characterized by the CEP prior to the test with 
8 "A"s. Riola exploded with only a small fraction 
of the expected yield. A surface collapse occurred 
and the failure of a containment plug resulted in the 
release of radioactive material. 

4. Agrini (March 31, 1984. vertical shaft test, less 
than 20 kilotons, radioactivity detected only on- 
site.) 

The Agrini explosion formed a deep subsidence 
crater 60 feet west of the emplacement hole. A small 
amount of radioactive material was pushed through 
the chimmney by noncondensible gas pressure and 
was detected onsite. The containment plan for 
Agrini received seven "A"sandtwo "B"s from the 
CEP prior to the test. The "B"s were due to the use 
of a new stemming plan. 

5. Midas Myth (February 15, 1984, horizontal 
tunnel test, less than 20 kilotons, no release of 
radioactive material.) 



All of the radioactive material produced by the 
Midas Myth test was contained within vessel I, with 
no release of radioactivity to either the atmosphere 
or the tunnel system. It is therefore not considered a 
containment failure. Three hours after the lest, 
however, the cavity collapsed and the chimney 
reached the surface forming an unanticipated subsi- 
dence crater. Equipment trailers were damaged and 
personnel were injured (one person later died as a 
result of complications from his injuries) when the 
collapse crater formed.^' Analysis conducted after 
the test indicated that the formation of the collapse 
crater should have been expected. Shots conducted 
on Yucca Flat with the same yield and at the same 
depth of burial did, at times, produce surface 
collapse craters. In the case of Midas Myth, collapse 
was not predicted because there had never been a 
collapse crater for a tunnel event and so the analysis 
was not made prior to the accident. After analyzing 
the test, the conclusion of the Surface Subsidence 
Review Committee was: 

That the crater is not an indication of some 
unusual, anomalous occurrence specific to the U 12X04 
emplacement site. Given the normal variation in 
explosion phenomena, along with yield, depth of 
burial, and geologic setting, experience indicates an 
appreciable chance for the foimation of a surface 
subsidence crater for Midas Myth. 

Prior to the test, the Containment Evaluation 
Panel characterized Midas Myth with nine "A"s. 

6. Misty Rain ( April 6, 1985, horizontal tunnel 
test, less than 20 kilotons, no unintentional release of 
radioactive material.) 

Misty Rain is unusual in that it is the only tunnel 
test since 1970 that did not have three containment 
vessels. In the Misty Rain test, the decision was 
made that because the tunnel system was so large, a 
vessel II was not needed.^^ Despite the lack of a 
vessel II, the CEP categorized the containment of 
Misty Rain with eight "A"s, and one "B."^^ During 
the test, an early flow of energy down the HLOS pipe 
prevented the complete closure of the MAC doors. 
The MAC doors overlapped, but stopped a couple 
inches short of full closure. The TAPS door closed 
only 20 percent before the deformation from ground 
shock prevented it from closing. A small amount of 



30lbid. 

3'The injuries were due to the physical circumstances of the collapse. There was no radiation exposure. 

'^The drifts in the tunnel system created over 4 million cubic feel of open volume. 

''One CEP member did not initially categorize the test, after receiving additional information concerning the test, he categorized the test with an " A. " 



Chapter 3 — Containing Underground Nuclear Explosions • 51 



radioactive material escaped down the pipe and then 
seeped from the HLOS pipe tunnel into the bypass 
tunnel. Subsequently, the tunnel was intentionally 
vented so that experimental equipment could be 
recovered. 

7. Mighty Oak (April 10, 1986, horizontal tunnel 
test, less than 20 kilotons, no unintentional release of 
radioactive material.) 

During the Mighty Oak test, the closure system 
near the working point was over-pressured and 
failed. The escaped pressure and temperature caused 
both the MAC and the GSAC to fail. The loss of the 
stemming plug near the working point left the tunnel 
an open pathway from the cavity. Temperatures and 
pressures on the closed TAPS door reached 2,000 °F 
and 1 ,400 pounds per square inch. After 50 seconds, 
the center part (approximately 6 feet in diameter) of 
the TAPS door broke through. With the closures 
removed, the stemming column squeezed out 
through the tunnel. Radioactive material leaked 
from vessel I, into vessel II, and into vessel III, where 
it was successfully contained. Approximately 85 
percent of the data from the prime test objectives was 
recovered, although about $32 million of normally 
recoverable and reusable equipment was lost.^'' 
Controlled purging of the tunnel began 1 2 days after 
the test and continued intermittently from April 22 
to May 19, when weather conditions were favorable. 
A total of 36,000 Ci were released to the atmosphere 
during this period. 

IS THERE A REAL ESTATE 
PROBLEM AT NTS? 

There have been over 600 underground and 100 
aboveground nuclear test explosions at the Nevada 
Test Site. With testing continuing at a rate of about 
a dozen tests a year, the question of whether there 
will eventually be no more room to test has been 
raised. While such a concern may be justified for the 
most convenient areas under the simplest arrange- 
ments, it is not justified for the test area in general. 
Using the drill-hole spacing of approximately one- 
half the depth of burial, high-yield tests can be 
spaced about 1,000 feet apart, and low-yield tests 
can be spaced at distances of a few hundred feet. 
Consequently, a suitable square mile of test site may 
provide space for up to 25 high-yield tests or over 



300 low-yield tests. Even with testing occurring at a 
rate of 1 2 tests a year, the 1 ,350 square miles of test 
site provide considerable space suitable for testing. 

In recent years, attempts have been made to use 
space more economically, so that the most conven- 
ient locations will remain available. Tests have 
traditionally been spaced in only 2-dimensions. It 
may be possible to space tests 3-dimensionally, that 
is, with testing located below or above earlier tests. 
Additionally, the test spacing has been mostiy for 
convenience. If available testing areas become 
scarce, it may become possible to test at closer 
spacing, or even to test at the same location as a 
previous test. 

Area for horizontal tunnel tests will also be 
available for the future. The N-tunnel area has been 
extended and has a sizable area for future testing. 
P-tunnel, which is used for low-yield effects tests, 
has only been started. (See figure 2-4 in ch. 2 of this 
report.) Within Rainier and Aqueduct Mesa alone, 
there is enough area to continue tunnel tests at a rate 
of two a year for at least the next 30 years. 
Consequently, lack of adequate real estate will not 
be a problem for nuclear testing for at least several 
more decades. 

TIRED MOUNTAIN SYNDROME? 

The "Tired Mountain Syndrome" hypothesis 
postulates that repeated testing in Rainier Mesa has 
created a "tired" mountain that no longer has the 
strength to contain future tests. Support for this 
concern has come from the observation of cracks in 
the ground on top of the Mesa and from seismologi- 
cal measurements, indicating that large volumes of 
rock lose strength during an underground test. 
Debate exists, however, over both the inference that 
the weakened rock is a danger to containment, and 
the premise that large volumes of rock are being 
weakened by nuclear testing. 

Basic to the concern over tired mountain syn- 
drome is the assumption that weakened rock will 
adversely affect containment. As discussed previ- 
ously, only in an extreme situation, such as detonat- 
ing an explosion in water-saturated clay, would rock 
strength be a factor in contributing to a leak of 
radioactive material. ^^ For example, many tests have 



^^Containment and Safety Review for the Mighty Oak Nuclear Weapon Effects Test. U.S. Department of Energy, Nevada Operations Office, N VO-3 1 1 , 
May 1, 1987. 

^'See earlier section "Why do nuclear tests remain contained?" 



52 • The Containment of Underground Nuclear Explosions 




Photo credit: Department of Energy 

Fracture on Rainier Mesa. 

been detonated in alluvial deposits, which are 
essentially big piles of sediment with nearly no 
internal strength in an unconfined state. Despite the 
weakness and lack of cohesiveness of the material, 
such explosions remain well contained. 

Compared to vertical drill hole tests, tunnel tests 
are overburied and conservatively spaced. The 
tunnel system in Rainier Mesa is at a depth of 1 ,300 
feet. By the standards for vertical drill hole tests 
(using the scaled depth formula^^), this is deep 
enough to test at yields of up to 34 kilotons; and yet 
all tunnel tests are less than 20 kilotons. ^^ Conse- 
quently, all tunnel tests in Rainier Mesa are buried 
at depths comparatively greater than vertical drill 
hole tests on Yucca Flat. Furthermore, the minimum 
separation distance of tunnel shots (twice the com- 
bined cavity radii plus 1(X) feet) results in a greater 
separation distance than the minimum separation 



distance of vertical drill hole shots ('/2 depth of 
burial) for tests of the same yield (compare figures 
3-2 and 3-3). Consequently, neither material 
strength, burial depth, nor separation distance 
would make leakage to the surface more likely for 
a tunnel test on Rainier Mesa than for a vertical 
drill hole tests on Yucca Flat. 

Despite the relative lack of importance of strength 
in preventing possible leakage to the surface, the 
volume of material weakened or fractured by an 
explosion is of interest because it could affect the 
performance of the tunnel closures and possible 
leakage of cavity gas to the tunnel complex. Dispute 
over the amount of rock fractured by an underground 
nuclear explosion stems from the following two, 
seemingly contradictory, but in fact consistent 
observations: 

1 . Post-shot measurements of rock samples taken 
from the tunnel complex generally show no change 
in the properties of the rock at a distance greater than 
3 cavity radii from the point of the explosion. This 
observation implies that rock strength is measurably 
decreased only within the small volume of radius = 
165 (yield) '\'^^ where the radius is measured in feet 
from the point of the explosion and the yield is 
measured in kilotons (figure 3-10). 

2. Seismic recordings of underground explosions 
at Rainier Mesa include signals that indicate the loss 
of strength in a volume of rock whose radius is 
slightly larger than the scaled depth of burial. This 
observation implies that the rock strength is de- 
creased throughout the large volume of radius = 500 
(yield) ^\ where the radius is measured in feet from 
the point of the explosion and the yield is measured 
in kilotons (figure 3-1 1). The loss of strength in a 
large volume seems to be further supported by 
cracks in the ground at the top of Rainier Mesa that 
were created by nuclear tests. 

The first observation is based on tests of samples 
obtained from drilling back into the rock surround- 
ing the tunnel complex after a test explosion. The 
core samples contain microft^actures out to a distance 
from the shot point equal to two cavity radii. 
Although microfractures are not seen past two cavity 
radii, measurements of seismic shear velocities 



36Depth(ft) = 400 (yield(kt))"' 
^^''AnnounccdUniiedStatesNuclearlfcsts.July 1945 through December 1987, 



United States Department ofEnergy. NVO-209(Rcv,8), April. 1988. 



"If the radius of a cavity produced by an explosion is equal to55(yield)"^, a distance of three cavity radii would be equal to three times this, or 165 
(yield)'". 



Chapter 3 — Containing Underground Nuclear Explosions • 53 



Figure 3-10 — Radius of Decrease in Rock Strength 




500 N/7" 



Seismic measurements and measurements taken from drill-back samples indicate a seemingly contradictory (but in fact consistent) radius 
of decrease in rock strength. 

SOURCE: Office of Tecfinology Assessment, 1989. 



continue to be low out to a distance of three cavity 
radii. The decrease in seismic shear velocity indi- 
cates that the rock has been stressed and the strength 
decreased. At distances greater than three cavity 



radii, seismic velocity measurements and strength 
tests typically show no change from their pre-shot 
values, although small disturbances along bedding 
planes are occasionally seen when the tunnels are 



54 • The Containment of Underground Nuclear Explosions 



re-entered after the test. Such measurements suggest 
that the explosion only affects rock strength to a 
distance from the shot point to about three cavity 
radii (165 (yield)'/'). 

The second observation, obtained from seismic 
measurements of tectonic release, suggests a larger 
radius for the volume of rock affected by an 
explosion. The seismic signals from underground 
nuclear explosions frequently contain signals cre- 
ated by what is called "tectonic release." By 
fracturing the rock, the explosion releases any 
preexisting natural stress that was locked within the 
rock. The release of the stress is similar to a small 
earthquake. The tectonic release observed in the 
seismic recordings of underground explosions from 
Rainier Mesa indicate the loss of strength in a 
volume of rock with a minimum radius equal to 500 
(yield)'/'. 

Although the drill samples and the seismic data 
appear to contradict each other, the following 
explanation appears to account for both: The force of 
the explosion creates a cavity and fractures rock out 
to the distance of 2 cavity radii from the shot point. 
Out to 3 cavity radii, existing cracks are extended 
and connected, resulting in a decrease in seismic 
shear velocity. Outside 3 cavity radii, no new cracks 
form. At this distance, existing cracks are opened 
and strength is reduced, but only temporarily. The 
open cracks close immediately after the shock wave 
passes due to the pressure exerted by the overlying 
rock. Because the cracks close and no new cracks are 
formed, the rock properties are not changed. Post- 
shot tests of seismic shear velocity and strength are 
the same as pre-shot measurements. This is consis- 
tent with both the observations of surface fractures 
and the slight disturbances seen along bedding 
planes at distances greater than 3 cavity radii. The 
surface fractures are due to surface spall, which 
would indicate that the rock was overloaded by the 
shock wave. The disturbances of the bedding planes 
would indicate that fractures are being opened out to 
greater distances than 3 cavity radii. In fact, the 
bedding plane disturbances are seen out to a distance 
of 600 (yield) /\ which is consistent with the radius 
determined from tectonic release. 

The large radius of weak rock derived from 
tectonic release measurements represents the tran- 
sient weakening from the shot. The small radius of 



weak rock derived from the post-shot tests repre- 
sents the volume where the rock properties have 
been permanently changed. From the point of view 
of the integrity of the tunnel system, it is the smaller 
area where the rock properties have been perma- 
nently changed (radius = 165 (yield)'/') that should 
be considered for containment. Because the line-of- 
sight tunnel is located so that the stemming plug 
region and closures are outside the region of 
permanently weakened or fractured material, the 
closure system is not degraded. 

HOW SAFE IS SAFE ENOUGH? 

Every nuclear test is designed to be contained and 
is reviewed for containment. In each step of the test 
procedure there is built-in redundancy and conserva- 
tism. Every attempt is made to keep the chance of 
containment failure as remote as possible. This 
conservatism and redundancy is essential, however; 
because no matter how perfect the process may be, 
it operates in an imperfect setting. For each test, the 
containment analysis is based on samples, estimates, 
and models that can only simplify and (at best) 
approximate the real complexities of the Earth. As a 
result, predictions about containment depend largely 
on judgments developed from past experience. Most 
of what is known to cause problems — carbonate 
material, water, faults, scarps, clays, etc. — was 
learned through experience. To withstand the conse- 
quences of a possible surprise, redundancy and 
conservatism is a requirement not an extravagance. 
Consequently, all efforts undertaken to ensure a safe 
testing program are necessary, and they must con- 
tinue to be vigorously pursued. 

Deciding whether the testing program is safe 
requires a judgement of how safe is safe enough. The 
subjective nature of this judgement is illustrated 
through the decision-making process of the CEP. 
which reviews and assesses the containment of each 
test.^^ They evaluate whether a test will be contained 
using the categorizations of "high confidence," 
' ' adequate degree of confidence, " and " some doubt. " 
But, the CEP has no guidelines that attempt to 
quantify or describe in probabilistic terms what 
constitutes for example, an "adequate degree of 
confidence." Obviously one can never have 1(X) 
percent confidence that a test will not release 
radioactive material. Whether "adequate confi- 



"The Containmenl Evaluation Panel is a group of representatives from various laboratories and technical consulting organizations who evaluate the 
proposed containment plan for each test without regard to cost or other outside considerations (see ch, 2 for a complete discussion). 



Chapter 3 — Containing Underground Nuclear Explosions • 55 



dence" translates into a chance of 1 in 100, 1 in 
1,000, or 1 in 1,000,000. requires a decision about 
what is an acceptable risk level. In turn, decisions of 
acceptable risk level can only be made by weighing 
the costs of an unintentional release against the 
benefits of testing. Consequently, those who feel 
that testing is important for our national security will 
accept greater risk, and those who oppose nuclear 
testing will find even small risks unacceptable. 

Establishing an acceptable level of risk is difficult 
not only because of value judgments associated with 
nuclear testing, but also because the risk is not seen 
as voluntary to those outside the testing program. 
Much higher risks associated with voluntary, every- 
day activities may be acceptable even though the 
much lower risks associated with the nuclear test site 
may still be considered unacceptable. 

The question of whether the testing program is 
"safe enough" will ultimately remain a value 



judgment that weighs the importance of testing 
against the risk to health and environment. In this 
sense, concern about safety will continue, largely 
fueled by concern about the nuclear testing program 
itself However, given the continuance of testing and 
the acceptance of the associated environmental 
damage, the question of "adequate safety" becomes 
replaced with the less subjective question of whether 
any improvements can be made to reduce the 
chances of an accidental release. In this regard, no 
areas for improvement have been identified. This is 
not to say that future improvements will not be made 
as experience increases, but only that essentially all 
suggestions that increase the safety margin have 
been implemented. The safeguards built into each 
test make the chances of an accidental release of 
radioactive material as remote as possible. 



Chapter 4 



Monitoring Accidental 
Radiation Releases 



I 



CONTENTS 

Page 

INTRODUCTION 59 

WHAT IS RADIATION? 59 

PRODUCTS OF A NUCLEAR EXPLOSION 59 

CRITERIA FOR CONDUCTING A TEST 60 

PREDICTING FALLOUT PATTERNS 63 

ACCIDENT NOTinCATION 64 

Onsite Monitoring by The Department of Energy 65 

Offsite Monitoring by The Environmental Protection Agency 66 

GROUNDWATER 70 

MONITORING CAPABILITY 74 

Figures 

Figure Page 

4-1. The Typical Bimodal Curve for Fission-Product Yield 60 

4-2. Controllable and Uncontrollable Areas 62 

4-3. Projected Fallout Dispersion Pattern 63 

4-4. Yield v. Distance 64 

4-5. Typical RAMs Array for Vertical Drill-Hole Shot 66 

4-6. Typical RAMs Array for Tbnnel Shot 67 

4-7. Air Monitoring Stations 69 

4-8. Sample Press Release 72 

4-9. Standby Air Surveillance Network Stations 73 

4-10. Locations Monitored With Thermoluminescent Dosimeters 74 

4-11. Milk Sampling Locations 75 

4-12. Standby Milk Surveillance Network 76 

4-13. Collection Site for Animals Sampled in 1987 77 

4-14. Locations of Families in the Offsite Human Surveillance Program 78 

4-15. Well Sampling Locations Onsite 79 

4-16. Well Sampling Locations Offsite 80 

Tables 

Table Page 

4-1. Common Radionuclides Involved in a Nuclear Explosion 60 

4-2. Summary of Onsite Environmental Monitoring Program 68 

4-3. Citizens Alert Water Sampling Program 78 



Chapter 4 
Monitoring Accidental Radiation Releases 



Each test is conducted under conditions in which remedial actions could be effective should an 
accidental release of radioactive material occur. 



INTRODUCTION 

Although nuclear tests are designed to minimize 
the chance that radioactive material could be re- 
leased to the atmosphere, it is assumed as a 
precaution for each test that an accident may occur. 
To reduce the impact of a possible accident, tests are 
conducted only under circumstances whereby reme- 
dial actions could be taken if necessary. If it is 
estimated that the projected radioactive fallout from 
a release would reach an area where remedial actions 
are not feasible, the test will be postponed. 

Responsibility for radiation safety measures for 
the nuclear testing program is divided between the 
Department of Energy (DOE) and the Environ- 
mental Protection Agency (EPA). The Department 
of Energy oversees monitoring within the bounda- 
ries of the Nevada Test Site (NTS). The Environ- 
mental Protection Agency monitors the population 
around the test site and evaluates the contribution of 
nuclear testing to human radiation exposure through 
air, water, and food. 

WHAT IS RADIATION? 

The nuclei of certain elements disintegrate spon- 
taneously. They may emit particles, or electromag- 
netic waves (gamma rays or x-rays), or both. These 
emissions constitute radiation. The isotopes are 
called radionuclides. They are said to be radioactive, 
and their property of emitting radiation is called 
radioactive decay. The rate of decay is characteristic 
of each particular radionuclide and provides a 
measure of its radioactivity. 

The common unit of radioactivity was the curie 
(Ci), defined as 3.7 x 10'" decays per second, which 
is the radioactivity of one gram of radium. Recently, 
a new unit, the becquerel (Bq), has been adopted, 
defined as one decay per second. Exposure of 
biological tissue to radiation is measured in terms of 
rems (standing for roentgen equivalent man). A 
roentgen (R) is a unit of exposure equivalent to the 



quantity of radiation required to produce one cou- 
lomb of electrical charge in one kilogram of dry air. 
A rem is the dose in tissue resulting from the 
absorption of a rad of radiation multiplied by a 
"quality factor" that depends on the type of 
radiation. A rad is defined as 100 ergs (a small unit 
of energy) per gram of exposed tissue. Recently 
accepted international units of radiation are now the 
gray (Gy), equal to 100 rads, and the sievert (Sv), 
equal to 100 rems. 



PRODUCTS OF A NUCLEAR 
EXPLOSION 

A nuclear explosion creates two sources of 
radioactivity: the first source is the direct products of 
the nuclear reaction, and the second is the radioactiv- 
ity induced in the surrounding material by the 
explosion-generated neutrons. In a fission reaction, 
the splitting of a nucleus creates two or more new 
nuclei that are often intensely radioactive. The 
products occur predominantly in two major groups 
of elements as shown in figure 4-1. The neutrons 
produced by the reaction also react with external 
materials such as the device canister, surrounding 
rock, etc., making those materials radioactive as 
well. In addition to these generated radioactivities, 
unbumed nuclear fission fuel (especially plutonium) 
is also a radioactive containment. The helium nuclei 
formed by fusion reactions are not radioactive.' 
However, neutrons produced in the fusion reaction 
still will make outside material radioactive. Depend- 
ing on the design of the explosive device and its 
percentage of fission and fusion, a wide range of 
radioactive material can be released with half lives 
of less than a second to more than a billion years.- 
The debris from nuclear detonations contain a large 
number of radioactive isotopes, which emit predom- 
inantly gamma and beta radiation. Some of the more 
common radionuclides involved in a nuclear explo- 
sion are listed in table 4-1. 



'This, incidentally, is why commercial fusion reactors (if they could be created) would be a relatively clean source of energy. 

^The half-life is the time required for half of the atoms of a radioactive substance to undergo a nuclear transformation to a more stable element. 



-59- 



60 • The Containment of Underground Nuclear Explosions 



Figure 4-1— The Typical Bimodal Curve for 
Fission-Product Yield 



2 10'' 



: 






,f 


^ 






/^ 


. 








' 






1 


1 


1 






1 














1 








u 








: 






1 


1 






\ ^ 








- 




j 


1 






1 




1 








: 






1 






1 




1 


\ 






: 




-f 


( 




«. 


1 






\ 






: 




1 

i 






— 





— 











70 82 94 106 118 130 142 154 166 

Mass number 

Products of a nuclear explosion occur predominantly in two major 
groups of nuclides. 

SOURCE; Modified from Lapp and Andrews, Prentice-Hall. Inc., 1972. 



Table 4-1 — Common Radionuclides Involved In a 
Nuclear Explosion 

Radionuclide Half-Life 

Uranium-238 4,500,000.000 years 

Plutonium-239 24,300 years 

Carbon-14 5,800 years 

Radium-226 1 ,620 years 

Cesium-137 30 years 

Strontium-90 28 years 

Tritium 12.3 years 

Krypton-85 10.9 years 

lodine-131 8 days 

Xenon-133 5.2 days 

lodine-132 2.4 hours 



The type of release is also important in predicting 
what radionuclides will be present. For example, 
atmospheric tests release all radionuclides created. 
Prompt, massive ventings have released a nonnegli- 
gible fraction of the radionuclides created. Late- 
time, minor seeps, like those since 1 970, release only 
the most volatile radionuclides. In an underground 
explosion, radionuclides also separate (called "frac- 
tionation") according to their chemical or physical 
characteristics. Refractory particles (particles that 
do not vaporize during the nuclear explosion) settle 
out fast underground, while more volatile elements 
that vaporize easily condense later. TTiis has a strong 
effect on radioactive gases that seep slowly through 
the soil from an underground explosion. In an 
underground explosion, nearly all the reactive mate- 
rials are filtered out through the soil column, and the 
only elements that come up through the soil to the 
atmosphere are the noble gases, primarily krypton 
and xenon. 



An individual radioactive species follows the 
half-life rule of decay — that is, half of the nuclei 
disintegrate in a characteristic time, called a "half- 
life." However, a mixture of fission products has a 
more complicated decay pattern. The general rule of 
thumb for a nuclear explosion is that the total 
activity decreases by a factor of 10 for every 
sevenfold increase in time. In other words, if the 
gamma radiation 1 hour after an explosion has an 
intensity of 100 units, then 7 hours later it will have 
an intensity of 10. Consequently, the time after the 
explosion has a dramatic effect on the amount of 
radioactivity. A 1 kiloton explosion in the atmos- 
phere will produce 41 billion curies 1 minute after 
determination, but this will decrease to 10 million 
curies in just 12 hours. 



CRITERIA FOR CONDUCTING 
A TEST 

Although every attempt is made to prevent the 
accidental release of radioactive material to the 
atmosphere, several safety programs are carried out 
for each test. These programs are designed to 
minimize the likelihood and extent of radiation 
exposure offsite and to reduce risks to people should 
an accidental release of radioactive material occur. 
The Environmental Protection Agency monitors the 
population around the test site and has established 
plans to protect people should an accident occur. 
EPA's preparations are aimed toward reducing the 
whole-body exposure of the off-site populace and to 
minimizing thyroid dose to offsite residents, particu- 



Chapter 4 — Monitoring Accidental Radiation Releases • 61 



larly from the ingestion of contaminated milk.^ The 
whole-body dose is the main concern. However, 
deposition of radioactive material on pastures can 
lead to concentration in milk obtained from cows 
that graze on those pastures. The infant thyroid doses 
from drinking milk from family cows is also 
assessed.** 

The Department of Energy's criteria for conduct- 
ing a test are: 

For tests at the Nevada Test Site, when consider- 
ing the event-day weather conditions and the specific 
event characteristics, calculations should be made 
using the most appropriate hypothetical release 
models which estimate the off-site exposures that 
could result from the most probable release scenario. 
Should such estimates indicate that off-site popula- 
tions, in areas where remedial actions to reduce 
whole-body exposures are not feasible, could receive 
average whole-body dose in excess of 0. 1 7 R/year 
(170 mR/year), the event shall be postponed until 
more favorable conditions prevail. In addition, 
events may proceed only where remedial actions 
against uptake of radionuclides in the food chain are 
practicable and/or indications are that average thy- 
roid doses to the population will not exceed 0.5 
R/year (500 mR/year).^ 

These criteria mean that a test can only take place 
if the estimate of the fallout from an accidental 
release of radioactivity would not be greater than 
0.17 Ryyear in areas that are uncontrollable, i.e., 
where "remedial actions to reduce whole-body 
exposures are not feasible." Thus, tests are not 
conducted when the wind is blowing in the general 
'direction of populated areas considered to be uncon- 
trollable, except under persistent light wind condi- 
jtions that would limit the significant fallout to the 
immediate vicinity of the NTS. Areas considered to 
be uncontrollable by EPA are shown in figure 4-2. 

The EPA and DOE have also defined a controlla- 
ble area (figure 4-2), within which remedial actions 
are considered feasible. Criteria for the controllable 
area, as defined by the DOE are: 

. . . those areas where trained rad-safe monitors are 
available, where communications are effective (where 
the exposure of each individual can be documented), 
where people can be expected to comply with 



recommended remedial actions, and where remedial 
actions against uptake of radionuclides in the food 
chain are practicable. 

The controllable area is the zone within approxi- 
mately 125 miles of the test control point (see figure 
4-2) for which EPA judges that its remedial actions 
would be effective. Within this area, EPA has the 
capability to track any release and perform remedial 
actions to reduce exposure, including sheltering or 
evacuation of all personnel (as needed); controlling 
access to the area; controlling livestock feeding 
practices, i.e., providing feed rather than allowing 
grazing; replacing milk; and controlling food and 
water. 

In the case of the controllable area, a test may be 
conducted if the fallout estimate implies that indi- 
viduals in the area would not receive whole-body 
doses in excess of 0.5 R/year and thyroid doses of 1 .5 
R/year. If winds measured by the weather service 
indicate that the cloud of radioactive debris pro- 
duced by the assumed venting would drift over 
controllable areas, such as to the north, the test is 
permitted when EPA's mobile monitors are in the 
downwind areas at populated places. EPA must be 
ready to measure exposure and to assist in moving 
people under cover or evacuating them, if necessary, 
to keep their exposures below allowable levels. 

As a consequence of the geometry of the control- 
lable area, tests are generally not conducted if winds 
aloft blow toward Las Vegas or towards other nearby 
populated locations. In addition, the test will not be 
conducted if there is less than 3 hours of daylight 
remaining to track the cloud. 

Prior to conducting a test, detailed fallout projec- 
tions are made by the weather service for the 
condition of "the unlikely event of a prompt 
massive venting." Predictions are made of the 
projected fallout pattern and the maximum radiation 
exposures that might occur. An example of such a 
prediction is shown in figure 4-3. The center line is 
the predicted path of maximum fallout deposition 
for a prompt venting, marked with estimated arrival 
times (in hours) at various distances. Lines to either 
side indicate the width of the fallout area. The two 
dashed lines indicate the 500 mR/year area and the 



^See "Offsile Remedial Action Capability for Underground Nuclear Weapons Tfest Accidents," U.S. Environmental Protection Agency. 
Environmental Monitoring Systems Laboratory — Las Vegas, NV, October 1988. 

' ''In the case of an accident, however, the actual dose would be minimized because the milk would be replaced as much as possible. 

'See "Offsite Remedial Action Capability for Underground Nuclear Weapons Tfest Accidents,"' U.S. Environmental Protection Agency, 
invu-onmental Monitoring Systems Laboratory — Las Vegas, NV, October 1988. 



62 • The Containment of Underground Nuclear Explosions 



Figure 4-2 — Controllable and Uncontrollable Areas 

Uncontrollable 




g 5 10 20 30 40 50 
Scale in miles 



The controllable area is the region within which remedial actions are considered feasible. 
SOURCE; Modified from Environmental Protection Agency. 



170 mR/year level. If 0.17 mR/year (the maximum 
external exposure allowed during a 12-month period 
for an uncontrolled population) or more is predicted 
to fall outside the controllable area, the test will be 



postponed. Within the predictions shown in figure; 
4-3. the test could be conducted if EPA monitors 
were prepared to be at each of the ranches, mines, 
and other populated areas within the dispersion 



Chapter 4 — Monitoring Accidental Radiation Releases • 63 



Figure 4-3 — Projected Fallout Dispersion Pattern 



Tonopah 




50 

1 I I .1 L_l 

Scale in miles 



;ey: H+ number= time of detonation plus elapsed liours; mR- milllREM 

Predicted fallout pattern for the case of an accidental venting. 

SOURCE: Modified from: "Public Safety for Nuclear Weapons Tests," U.S. 
I Environmental Protection Agency, January 1984. 

pattern to measure exposure and perform remedial 
[actions should they be necessary. 

I The preferred weather conditions for a test are a 
1 clear sky for tracking, southerly winds (winds from 
Ithe south), no thunderstorms or precipitation that 
1 would inhibit evacuation, and stable weather pat- 
items. During the test preparations, the Weather 
i Service Nuclear Support Office provides the Test 
Controller with predicted weather conditions. This 
information is used by the Weather Service to derive 
]the estimated fallout pattern should an accidental 
release occur. About one-third of all nuclear tests are 
delayed for weather considerations; the maximum 
jdelay in recent years reached 16 days. 



PREDICTING FALLOUT 
PATTERNS 

The predicted fallout pattern from an underground 
test depends on many variables related to the type of 
nuclear device, the device's material composition, 
type of venting, weather conditions, etc. With so 
many variables and so little experience with actual 
ventings, fallout predictions can only be considered 
approximations. The accuracy of this approxima- 
tion, however, is critical to the decision of whether 
a test can be safely conducted. Fallout predictions 
are made by the Weather Service Nuclear Support 
Office using up-to-date detailed weather forecasts 
combined with a model for a "prompt massive 
venting." The model uses scaling technique based 
on the actual venting of an underground test that 
occurred on March 13, 1964. The test, named 
"Pike," was a low-yield (less than 20 kilotons) 
explosion detonated in a vertical shaft. A massive 
venting occurred 10 to 15 seconds after detonation.^ 
The venting continued for 69 seconds, at which time 
the overburden rock collapsed forming a surface 
subsidence crater and blocking further venting. The 
vented radioactive debris, consisting of gaseous and 
particulate material, rose rapidly to about 3.000 feet 
above the surface. 

The Pike scaling model has been used to calculate 
estimates of fallout patterns for the past 20 years 
because: 1) the large amount of data collected from 
the Pike venting allowed the development of a 
scaling model, and 2) Pike is considered to be the 
worst venting in terms of potential exposure to the 
public.^ 

The Pike model, however, is based on a very small 
release of radioactive material compared to what 
would be expected from an aboveground test of the 
same size.** The percentage of radioactive material 
released from the Baneberry venting (7 percent from 
table 3-1), for example, is many times greater than 
the percentage of material released from the Pike 
test.^ It would therefore appear that Baneberry 
provides a more conservative model than Pike. This, 
however, is not the case because Baneberry was not 



"^Pikc was conducted in alluvium in Area 3 of the test site. The release was attributed lo a fracture that propagated to the surface. Other factors 
:ontnbuling to the release were an inadequate depth of burial and an inadequate closure of the line-of-sighl pipe. 

'"1985 Analyses and Evaluations of the Radiological and Meteorological Data from ihc Pike Event." National Oceanic and Atmospheric 
lAdministralion, Weather Service Nuclear Support Office, Las Vegas, NV, December, 1986, NVO-308. 

'The exact amount of material released from the 1964 Pike test remains classified. 
'See table 3-1 for a comparison of various releases. 



64 • The Containment of Underground Nuclear Explosions 



a prompt venting. Baneberry vented through a 
fissure and decaying radioactive material was 
pumped out over many hours. Baneberry released 
more curies than Pike; however, due to its slower 
release, a higher percentage of the Baneberry 
material was in the form of noble gases, which are 
not deposited. The data suggest that much less than 
7 percent of the released material was deposited. '° 
Therefore, it is thought that Pike is actually a more 
conservative model than Baneberry. 

The sensitivity of the Pike model can be judged by 
looking at the degree to which its predictions are 
affected by the amount of material released. For 
example, consider a test in which 10 percent of the 
radioactive material produced by the explosion is 
accidentally released into the atmosphere; in other 
words, 10 percent of the material that would have 
been released if the explosion had been detonated 
aboveground. This also roughly corresponds to the 
amount of material that would be released if the 
explosion had been detonated underground at the 
bottom of an open (unstemmed) hole. The 10 percent 
release can therefore be used as a rough approxima- 
tion for the worst case release from an underground 
test. To evaluate the adequacy of the Pike model 
predictions to withstand the full range of uncertainty 
of an accidental release, the question is: what effect 
would a release of 10 percent rather than, say 1 
percent, have on the location of 170-mR and 
500-mR exposure lines? As figure 4-4 illustrates, 
changing the yield of an explosion by an order of 
magnitude (in other words, increasing the release 
from say 1 percent to 10 percent) increases the 
distance of the 170-mR and 500-mR lines by 
roughly a factor of 2. Therefore, assuming a worst 
case scenario of a 10 percent prompt massive 
venting (as opposed to the more probable scenario of 
around a 1 percent prompt massive venting), the 
distance of the exposure levels along the predicted 
fallout lines would only increase by a multiple of 2. 
The Pike model therefore provides a prediction that 
is at least within a factor of about 2 of almost any 
possible worst-case scenario. 

ACCIDENT NOTIFICATION 

Any release of radioactive material is publicly 
announced if the release occurs during, or immedi- 
ately following, a test. If a late-time seep occurs, the 
release will be announced if it is predicted that the 



Figure 4-4 — Yield v. Distance 



1.000 cr 



Total 1st year Total 1st year 
exposure exposure 

500 mR 170 mR 




Distance (miles) 



Constant Pil(e Parameters 

Wind speed = 15mph 
Vertical wind shear = 20° 
Cloud rise = 5,000ft 



Variable 

Yield* Pike 



Yield (in kilotons) v. distance (in miles) for projected fallout using 
the Pike Model. TYE indicates total first year exposure. Increasing 
tfie yield by a factor of 1 rougfily doubles tfie downwind distance 
of the projected fallout pattern. 

SOURCE: Provided by National Oceanic and Atmospheric Administration, 
National Wsather Service Nuclear Support Office, 1988. 

radioactive material will be detected outside the 
boundaries of the test site. If no detection off-site is 
predicted, the release may not be announced. 

Operational releases that are considered routine 
(such as small releases from drill-back operations) 
are similarly announced only if it is estimated that 
they will be detected off-site. 

The Environmental Protection Agency is present 
at every test and is therefore immediately aware of 
any prompt release. The Environmental Protection 
Agency, however, is not present at post-test drill- 
back operations. In the case of late-time releases or 
operational releases, the Environmental Protection 
Agency depends on notification from the Depart- 
ment of Energy and on detection of the release (once 



'"Baneberry, however, had a limited data set of usable radioactive readings. 



Chapter 4 — Monitoring Accidental Radiation Releases • 65 



' it has reached outside the borders of the test site) by 
the EPA offsite monitoring system. 

Estimates of whether a particular release will be 
detected offsite are made by the Department of 
Energy or the sponsoring laboratory. Such judg- 
ments, however, are not always correct. During the 
drill-back operations of the Glencoe test in 1986, 
minor levels of radioactive material were detected 
offsite contrary to expectations. During the Riola 
test in 1980, minor amounts of radioactive inert 
gases were detected offsite. In both cases. DOE 
personnel did not anticipate the release to be 
detected offsite and therefore did not notify EPA." 
Although the releases were extremely minor and 
well-monitored within the test site by DOE, EPA 
was not aware of the release until the material had 
crossed the test site boundaries. Both cases fueled 
concern over DOE's willingness to announce acci- 
dents at the test site. The failure of DOE to publicly 
announce all releases, regardless of size or cir- 
cumstance, contributes to public concerns over 
the secrecy of the testing program and reinforces 
the perceptions that all the dangers of the testing 
program are not being openly disclosed. 

Onsite Monitoring by the 
Department of Energy 

The Department of Energy has responsibility for 
monitoring within the boundaries of the Nevada Test 
Site to evaluate the containment of radioactivity 
onsite and to assess doses-to-man from radioactive 
releases as a result of DOE operations. To achieve 
these objectives, DOE uses a comprehensive moni- 
toring system that includes both real-time monitor- 
ing equipment and sample recovery equipment. The 
real-time monitoring system is used for prompt 
detection following a test, the sample recovery 
equipment is used to assess long-term dose and risk. 

The heart of the real-time monitoring system is a 
network of Remote Area Monitors (RAMs). For all 
tests, RAMs are arranged in an array around the test 
hole (figure 4-5). Radiation detectors are also 
frequently installed down the stemming column so 
the flow of radioactive material up the emplacement 
hole can be monitored. In tunnel shots, there are 
RAMs above the shot point, throughout the tunnel 
complex, outside the tunnel entrance, and in each 
containment vessel (figure 4-6). In addition to 



RAMs positioned for each shot, a permanent RAM 
network with stations throughout the test site is in 
continual operation. 

During each test, a helicopter with closed-circuit 
television circles the ground zero location. Nearby. 
a second helicopter and an airplane are prepared to 
track any release that might occur. A third helicopter 
and an airplane remain on stand-by should they be 
needed. In addition, a team (called the "Bluebird 
Team"), consisting of trained personnel in 2 four- 
wheel drive vehicles outfitted with detection equip- 
ment and personnel protection gear is stationed near 
the projected fallout area to track and monitor any 
release. Approximately 50 radiation monitoring 
personnel are available on the Nevada Test Site to 
make measurements of exposure rates and collect 
samples for laboratory analysis should they be 
needed. Prior to the test, portions of the test site are 
evacuated unless the operation requires manned 
stations. If manned stations are required, direct 
communication links are established with the work- 
ers and evacuation routes are set-up. 

In addition to the real-time monitoring network, 
air and water samples are collected throughout the 
Test Site and analyzed at regular intervals. This 
comprehensive environmental monitoring program 
is summarized in table 4-2. The network of samplers 
located throughout the Test Site includes 160 
thermoluminescent dosimeters; over 40 air samplers 
that collect samples for analysis of radioiodines. 
gross beta, and plutonium-239; and about half a 
dozen noble gas samplers. Each year over 4,500 
samples are collected and analyzed for radiological 
measurement and characterization of the Nevada 
Test Site. All sample collection, preparation, analy- 
sis, and review are performed by the staff of the 
Laboratory Operations Section of REECO's Envi- 
ronmental Sciences Department. 

In the case of a prompt, massive accidental release 
of radioactive material, the following emergency 
procedures would be initiated: 

1. any remaining test site employees downwind 
of the release would be evacuated, 

2. monitoring teams and radiological experts 
would be dispatched to offsite downwind 
areas. 



"In the case of Riola, the release occurred in the evening and was not reported until the following morning. As a result, it was 1 2'/^ hours before EPA 
was notified. 



66 • The Containment of Underground Nuclear Explosions 



Figure 4-5 — Typical RAMs Array for Vertical 
Drill-Hole Shot 



Post shot access Rd. 




Plug truck access rd. 



In addition to the RAMs located down the drill hole, nine RAMs are 
placed at the surface around the test hole. 

SOURCE: Modified from Department of Energy 

3. ground and airborne monitoring teams would 
measure radioactive fallout and track the 
radioactive cloud, 

4. Federal, State, and local authorities would be 
notified, and 

5. if necessary, persons off-site would be re- 
quested to remain indoors or to evacuate the 
area for a short time.'- 

Offsite Monitoring by the Environmental 
Protection Agency 

Under an interagency agreement with the Depart- 
ment of Energy, the Environmental Protection 
Agency is responsible for evaluating human radia- 
tion exposure from ingesting air, water, and food that 
may have been affected by nuclear testing. To 
accomplish this, EPA collects over 8,700 samples 
each year and performs over 15,000 analytical 



measurements on water, milk, air, soil, humans, 
plants, and animals.'^ The sampling system and 
results are published annually in EPA's "Offsite 
Environmental Monitoring Report, Radiation Moni- 
toring Around United States Nuclear Test Areas." 

The heart of the EPA monitoring system is the 
network of 18 community monitoring stations. The 
community monitoring program began in 1981 and 
was modeled after a similar program instituted in the 
area surrounding the Three Mile Island nuclear 
reactor power plant in Pennsylvania. Community 
participation allows residents to verify independ- 
ently the information being released by the govern- 
ment and thereby provide reassurance to the commu- 
nity at large. The program is run in parmership with 
several institutions. The Department of Energy 
funds the program and provides the equipment. The 
Environmental Protection Agency maintains the 
equipment, analyzes collected samples, and inter- 
prets results. The Desert Research Institute manages 
the network, employs local station managers, and 
independently provides quality assurance and data 
interpretation. The University of Utah trains the 
station managers selected by the various communi- 
ties. Whenever possible, residents with some scien- 
tific training (such as science teachers) are chosen as 
station managers. 

There are 18 community monitoring stations 
(shown as squares in figure 4-7) located around the 
test site. The equipment available to each station 
includes;''' 

Noble Gas Samplers: These samplers compress 
air in a tank. The air sample is then analyzed to 
measure the concentration of such radioactive noble 
gases as xenon and krypton. 

Tritium Sampler: These samplers remove mois- 
ture from the air. The moisture is then analyzed to 
measure the concentration of tritium in the air. 

Particulates and Reactive Gases Sampler: These 
samplers draw 2 cubic feet of air per minute through 
a paper filter and then through a canister of activated 
charcoal. The paper filter collects particles and the 
charcoal collects reactive gases. Both are analyzed 
for radioactivity. 



'^Modified from "Onsite Environmental Report for the Nevada Tfest Site" (January 1987 through December 1987), Daniel A. Gon/.alcz, REECo., 
inc., DOE/NV/10327-39. 

'^In addition, EPA annually visits each location outside the Nevada Test Site where a nuclear test has occurred. 
'^"Community Radiation Monitoring Program," U.S. Environmental Protection Agency, January 1984. 



Chapter 4 — Monitoring Accidental Radiation Releases • 67 



Figure 4-6— lypical RAMs Array for TUnnel Shot ("Mission Cyber," Dec. 2, 1988) 

Surface Locations 




# RAM Locations 



_| = 200 



A total of 41 RAI*^s (15 above tfie surface, 26 belowground) are used to monitor the containment of radioactive material from a horizontal 
tunnel test 

SOURCE: Modified from Department of Energy 



Thermoluminescent Dosimeter (TLD): When 
heated (thermo-), the TLD releases absorbed energy 
in the form of light (-luminescent). The intensity of 
the light is proportional to the gamma radiation 
absorbed, allowing calculation of the total gamma 
radiation exposure. 

Gamma Radiation Exposure Rate Recorder: A 

pressurized ion chamber detector for gamma radia- 
tion is connected to a recorder so that a continuous 



record of gamma radiation is obtained and changes 
in the normal gamma radiation level are easily seen. 

Microbarograph: This instrument measures and 
records barometric pressure. The data are useful in 
interpreting gamma radiation exposure rate records. 
At lower atmospheric pressure, naturally occurring 
radioactive gases (like radon) are released in greater 
amounts from the Earth's surface and their radioac- 
tive decay contributes to total radiation exposure. 



68 • The Containment of Underground Nuclear Explosions 



Table 4-2 — Summary of Onsite Environmental Monitoring Program 

Collection Number 
Sample type Description frequency of locations Analysis 

Air Continuous sampling through Weekly 44 Gamma Spectroscopy gross beta, Pu-239 

gas filter & charcoal cartridge 

Low-volume sampling through Biweekly 16 Tritium (HTO) 

silica gel 

Continuous low volume Weekly 7 Noble gases 

Potable water 1 -liter grab sample Weekly 7 Gamma Spectroscopy gross beta.tritium Pu- 

239 (quarterly) 
Supply wells 1 -liter grab sample Monthly 1 6 Gamma Spectroscopy gross beta.tritium Pu- 

239 (quarterly) 
Open reservoirs 1 -liter grab sample Monthly 1 7* Gamma Spectroscopy gross beta.tritium Pu- 

239 (quarterly) 
Natural springs 1 -liter grab sample Monthly 9* Gamma Spectroscopy gross beta.tritium Pu- 

239 (quarteriy) 
Ponds (contaminated) 1 -liter grab sample Monthly 8" Gamma Spectroscopy gross beta.tritium Pu- 

239 (quarteriy) 
Ponds (effluent) 1 -liter grab sample Monthly 5 Gamma Spectroscopy gross beta.tritium Pu- 

239 (quarteriy) 
External gamma radiation 

levels Thermoluminescent Semi- 153 Total integrated exposure over field cycle 

Dosimeters annually 

'Not all of tfiese locations were sampled due to inaccessibility or lack of water. 




Photo credit: David Graham. 19 



Community Monitoring Station. Las Vegas, NV. 



Chapter 4 — Monitoring Accidental Radiation Releases • 69 



Figure 4-7— Air Monitoring Stations 




Nevada 



(D 



Austin 



Ely 



® 



Sunnyside 



Stone Cabin Rn. Blue Eagle Rn. 
Vj/ • Nyala 



® 



Goldfield • ^^'" Springs Rn. 

• hr ^_^ 



(Rachel 



Scotty's Jet. 



Beatty 



® 



Nevada 

Test 

Site 



Groom 
Lake 



(i) 



I Pioche 
I 
HIko (■)Caliente 



Indian 
Springs 



Lathrop Wells (W — ^/^ 

A Pahrump /^\ x-^ 

Furnace Creek 9 \L"y (H) 

Death Valley Jct.#^ 
Shoshone 




(i) 

Salt Lake City 



Delta 



I Milford 



(i) 



Cedar City 



(||)st. George 
Arizona 



(D 



Community monitoring stations 
Community monitoring stations with noble 
gas and tritium samplers 

Additional air surveillance network stations 





SOURCE: Modified from Environmental Protection Agency. 



70 • The Containment of Underground Nuclear Explosions 



The monitoring stations are extremely sensi- 
tive; they can detect changes in radiation exposure 
due to changing weather conditions. For example, 
during periods of low atmospheric pressure, gamma 
exposure rates are elevated on the order of 2 to 4 
uR/hr because of the natural radioactive products 
being drawn out of the ground. To inform the public, 
data from the community monitoring stations are 
posted at each station and sent to local newspapers 
(figure 4-8). 

In addition to the 18 community monitoring 
stations, 13 other locations are used for the Air 
Surveillance Network (shown as circles in figure 
4-7) to monitor particulates and reactive gases. The 
air surveillance network is designed to cover the area 
within 350 kilometers of the Nevada Test Site, with 
a concentration of stations in the prevailing down- 
wind direction. The air samplers draw air through 
glass fiber filters to collect airborne particles (dust). 
Charcoal filters are placed behind the glass fiber 
filters to collect reactive gases. These air samplers 
are operated continuously and samples are collected 
three times a week. The Air Surveillance Network is 
supplemented by 86 standby air sampling stations 
located in every State west of the Mississippi River 
(figure 4-9). These stations are ready for use as 
needed and are operated by local individuals or 
agencies. Standby stations are used 1 to 2 weeks 
each quarter to maintain operational capability and 
detect long-term trends. 

Noble gas and tritium samplers are present at 1 7 
of the air monitoring stations (marked with asterisk 
in figure 4-7). The samplers are located at stations 
close to the test site and in areas of relatively low 
altitude where wind drains from the test site. Noble 
gases, like krypton and xenon, are nonreactive and 
are sampled by compressing air in pressure tanks. 
Tritium, which is the radioactive form of hydrogen, 
is reactive but occurs in the form of water vapor in 
air. It is sampled by trapping atmospheric moisture. 
The noble gas and tritium samplers are in continuous 
operation and samples are recovered and analyzed 
weekly. 

To monitor total radiation doses, a network of 
approximately 130 TLDs is operated by EPA. The 
network encircles the test site out to a distance of 
about 400 miles with somewhat of a concentration in 
the zones of predicted fallout (figure 4-10). The TLD 
network is designed to measure environmental 
radiation exposures at a location rather than expo- 



sures to a specific individual. By measuring expo- 
sures at fixed locations, it is possible to determine 
the maximum exposure an individual would have 
received had he or she been continually present at 
that location. In addition, about 50 people living near 
the test site and all personnel who work on the test 
site wear TLD's. All TLD's are checked every 3 
months for absorbed radiation. 

Radioactive material is deposited from the air 
onto pastures. Grazing cows concentrate certain 
radionuclides, such as iodine-131 , strontium-90, and 
cesium- 137 in their milk. The milk therefore be- 
comes a convenient and sensitive indicator of the 
fallout. The Environmental Protection Agency ana- 
lyzes samples of raw milk each month from about 25 
farms (both family farms and commercial dairies) 
surrounding the test site (figure 4-1 1). In addition to 
monthly samples, a standby milk surveillance net- 
work of 120 Grade A milk producers in all States 
west of the Mississippi River can provide samples in 
case of an accident (figure 4-12). Samples from the 
standby network are collected annually. 

Another potential exposure route of humans to 
radionuclides is through meat of local animals. 
Samples of muscle, lung, liver, kidney, blood, and 
bone are collected periodically from cattle pur- 
chased from commercial herds that graze northeast 
of the test site. In addition, samples of sheep, deer, 
horses, and other animals killed by hunters or 
accidents are used (figure 4-13). Soft tissues are 
analyzed for gamma-emitters. Bone and liver are 
analyzed for strontium and plutonium; and blood/ 
urine or soft tissue is analyzed for tritium. 

A human surveillance program is also carried out 
to measure the levels of radioactive nuclides in 
families residing in communities and ranches around 
the test site (figure 4-14). About 40 families living 
near the test site are analyzed twice a year. A 
whole-body count of each person is made to assess 
the presence of gamma-emitting radionuclides. 

GROUNDWATER 

About 100 underground nuclear tests have been 
conducted directly in the groundwater. In addition, 
many pathways exist for radioactive material from 
other underground tests (tests either above or below 
the water table) to migrate from the test cavities to 
the groundwater. To detect the migration of radioac- 
tivity from nuclear testing to potable water sources, 
a long-term hydrological monitoring program is 



Chapter 4 — Monitoring Accidental Radiation Releases • 71 




Photo credit: David Graham, 



Whole Body Counter, Environmental Protection Agency. 



managed by the Environmental Protection Agency 
at the Department of Energy's direction with advice 
on sampling locations being obtained from the U.S. 
Geological Survey. Whenever possible, water sam- 
ples are collected from wells downstream (in the 
direction of movement of underground water) from 
sites of nuclear detonations. On the Nevada Test 
Site, about 22 wells are sampled monthly (figure 
4-15). The 29 wells around the Nevada Test Site 
(figure 4-16) are also sampled monthly and analyzed 
for tritium semiannually. 

The flow of groundwater through the Nevada Test 
Site is in a south-southwesterly direction. The flow 
speed is estimated to be about 10 feet per year, 
although in some areas it may move as fast as 600 
feet per year. To study the migration of radionu- 



clides from underground tests. DOE drilled a test 
well near a nuclear weapons test named "Cambric."" 
Cambric had a yield of 0.75 kilotons and was 
detonated in a vertical drill hole in 1965. A test well 
was drilled to a depth of 200 feet below the cavity 
created by Cambric. It was found that most of the 
radioactivity produced by the test was retained 
within the fused rock formed by the explosion, 
although low concentrations of radioactive material 
were found in the water at the bottom of the cavity.'^ 
A satellite well was also drilled 300 feet from the 
cavity. More than 3 billion gallons of water were 
pumped from the satellite well in an effort to draw 
water from the region of the nuclear explosion. The 
only radioactive materials found in the water were 
extremely small quantities (below the permitted 



"See "Radionuclide Migralion in Groundwater al NTS," U.S. Depanmcni of Energy, September, 1987. 



72 • The Containment of Underground Nuclear Explosions 



Alamo, IW 



Figure 4-8 — Sample Press Release 



July 11 to July 20, 1988 

The Nevada Test Site 

COMMUNITY RADIATION MONITORING REPORT 




ft J V>EPA 



Dell Sullivan, Manager of the Community Radiation Monitoring Station in 
Alamo, NV reported the results of the radiation measurements at this station 
for the period July 11 to July 20, 1988. The average gamma radiation exposure 
rate recorded by a Pressurized Ion Chamber at this station was 13.0 
microroentgens* per hour as shown on the chart. 

AVERAGE GAMMA RADIATION EXPOSURE RATE 
RECORDED ON THE PRESSURIZED ION CHAMBER AT 
ALAMO, NV, DURING THE WEEK ENDING JULY 20, 1988 



This Week 




-A 






Last Week 








Last Year 




U.S.Background'' 


h 



10 20 

Microroentgens Per Hour 



The averages of the 16 Community Monitoring Stations operated for the 
Environmental Protection Agency, Department of Energy and the Desert 
Research Institute varied from 6.2 microroentgens per hour at Las Vegas, NV 
to 20.2 microroentgens per hour at Austin, N\'. All of the rates for the past week 
were within the normal background range for the United States as shown on the 
accompanying chart. Environmental radiation exposure rates vary with 
altitude and natural radioactivity in the soil. Additional information and 
detailed data obtained from Community Radiation Monitoring Network 
Stations, including an annual summary of the results from all monitoring 
around the Nevada Test Site, can be obtained from Mr. Sullivan (702) 725-3544 
or by calling Charles F. Costa at the EPA in Las Vegas (702) 798-2305. 

The roentgen is a measure of exposure to X or gamma radiation. A microroenteen is 1 
millionth or a roentgen. For comparison, one chest x-ray results in an exposure of 10,000 to 
20,000 microroentgens. 

Sum of cosmic plus terrestrial dose rales in air in the U.S.(pp37,42, BEIR III, 1980). 

Example of community radiation monitoring report that is posted at each monitoring station and sent to the press. 
SOURCE; Environmental Protection Agency. 



Chapter 4 — Monitoring Accidental Radiation Releases • 73 



Figure 4-9 — Standby Air Surveiiiance Network Stations 

Canada 
11* 

^^^^'ngton I \ Montana 




^^ Scale in Miles 

^ 100 300 500 

I I ' l I' M I ' l ' i 

100 300 500 700 
Scale in Kilometers 



86 standby air surveillance stations are available and samples are collected and analyzed every 3 months to maintain a data base. 

SOURCE: Modified from Environmental Protection Agency. 



level for drinking water) of krypton-85, chlorine-36, 
ruthenium- 106, technetium-99 and iodine- 129. 

Radioactive material from nuclear testing moves 
through the groundwater at various rates and is 
filtered by rock and sediment particles. Tritium, 
however, is an isotope of hydrogen and becomes 
incorporated in water molecules. As a result, tritium 
moves at the same rate as groundwater. Tritium is 



therefore the most mobile of the radioactive materi- 
als. Although tritium migrates, the short half-life of 
tritium (12.3 years) and slow movement of the 
groundwater prevents it from reaching the Test Site 
boundary. No analysis of groundwater has ever 
found tritium at a distance greater than a few 
hundred meters from some of the old test sites. None 
of the water samples collected outside the bounda- 



74 • The Containment of Underground Nuclear Explosions 



Figure 4-10 — Locations Monitored With Thermoluminescent Dosimeters (TLDs) 



Winnemucca 



Wells 



Eldo 



Pyramid Lake 



<\ 



Reno 



Austin 



Carson^ 
City 



Mono ' 
Lake 



Ely. 



Tonopati^ 



Bistiop 



I Nellis^-- *• 
Range 



rs 



Alamo 



Salt 
Lake 




Salt 
Lake 
City 



.Lathrop . 
Wells Las 

' Vegas 




Lake Mead 



Bakerstield 



Barstow 



50 

Scale in Miles 



One hundred thirty locations are monitored with TLDs. All TLDs are checked every 3 months for absorbed radiation. 
SOURCE: Modified from Environmental Protection Agency. 



ries of the test site has ever had detectable levels of 
radioactivity attributable to the nuclear testing 
program. An independent test of water samples from 
around the test site was conducted by Citizen Alert 
(Reno, Nevada) at 14 locations (table 4-3). 

Citizen Alert found no detectable levels of tritium 
or fission products in any of their samples. With- 
standing any major change in the water table, there 
currently appears to be no problem associated with 



groundwater contamination offsite of the Nevada 
Test Site. 

MONITORING CAPABILITY 

The combination of: 1) the monitoring system 
deployed for each test, 2) the onsite monitoring 
system run by DOE, and 3) the offsite monitoring 
system run by EPA, forms a comprehensive detec- 
tion system for radioactive material. There is 



Chapter 4 — Monitoring Accidental Radiation Releases • 75 



Figure 4-11 — Milk Sampling Lx>catlons 



• Young Rn. 



Larsen Rn. • 



Burdick Rn 



Harbecke Rn. 



Round Mtn 
Berg Rn 



Twin Spgs Rn 



■ r, Lund 

Manzonie Rn • McKenzie Dairy 

Currant • 

• Blue Eagle Rn. 



Nyala 
Sharp's Rn. 

Penoyer 

1 Farms • „ 
i-| Darrel Hansen 

I . Rn. 



June Cox 
Rn. 



Brent Jones 
Dairy 




Scale in Miles 




50 

1 1 


100 


1 1 1 

50 100 


150 


Scale in Kilometers 




• Milk sampling locations 





Cedarsage Farm 



• Bill Nelson Dairy 
Hinkley 



Samples of raw milk are collected each month from about 25 farms surrounding the test site. 
SOURCE: Modified from Environmental Protection Agency. 



76 • The Containment of Underground Nuclear Explosions 



Figure 4-12— Standby Milk Surveiliance Network 




All major mllksheds west of the Mississippi River are part of thie standby milk surveillance network. 
Samples are collected and analyzed annually. 

SOURCE: Modified from Environmental Protection Agency. 



essentially no possibility that a significant release 
of radioactive material from an underground 
nuclear test could go undetected. Similarly, there 
is essentially no chance that radioactive material 
could reach a pathway to humans and not be 
discovered by the Environmental Protection Agency. 
Allegations that a release of radioactive material 
could escape from the test site undetected are based 
on partial studies that only looked at a small portion 
of the total monitoring system.'* Such criticisms are 
invalid when assessed in terms of the total monitor- 
ing system. 

The radiation monitoring system continues to 
improve as new measurement systems and tech- 
niques become available and as health risks from 
radiation become better understood. Assuming that 



the monitoring effort will continue to evolve, and 
that such issues as the migration of radioactive 
material in groundwater will continue to be aggres- 
sively addressed, there appear to be no valid criti- 
cisms associated with the containment of under- 
ground nuclear explosions. This is not to say that 
future improvement will not be made as experience 
increases, but only that essentially all relevant 
suggestions made to date that increase the safety 
margin have been implemented. 

Public confidence in the monitoring system suf- 
fers from a general lack of confidence in the 
Department of Energy that emanates from the 
enivronmental problems at nuclear weapons produc- 
tion facilities and from the radiation hazards associ- 
ated with past atmospheric tests. In the case of the 



'''Sec for example, "A review of off-site cnvironmenial monitoring of ihc Nevada Test Site.' ' Bcmd Franke. Health Effects of Underground Nuclear 
Tests, Oversight Hearing before the Subcommittee on Energy and the Environment of the Committee on Interior and Insular Affairs, Hou.se of 
Representatives, Sept. 25. 1987, Serial No. 100-35, pp. 120-144. 



Chapter 4 — Monitoring Accidental Radiation Releases • 77 



Figure 4-13— Collection Site for Animals Sampled in 1987 



o 



o 



Q.C. Smt. 




O 



O 



o 


Bighorn Sheep 


D 


Mule Deer 


▲ 


Cattle 


♦ 


Chukar 


■ 


Horse 






o 

vO 



Depending on availability, an assortment of animals are analyzed each year. 

SOURCE: Modified from Environmental Protection Agency. 



7S • The Containment of Underground Nuclear Explosions 



Table 4-3 — Citizen Alert Water Sampling Program 



Location 



Type of Sample 



Springdale Ranch 

Barley Hot Springs 

3 mi. south of Flourspar Canyon 

Lathrop Wells 

Point of Rock Spring. Ash Meadows 

Devils Hole, Ash Meadows 

Shoshone, CA 

Amargosa Junction 

Goldfield 

Moore's Station 

Six Mile Creek 

Tytio and Route 6 {DOE facility) 

Hot Creek and Route 6 

Blue Jay 



Well (hose) 

Stream 

Amargosa River 

Spigot at gas station 

Pond 

Pool 

Stream 

Well (hose) 

Well (spigot at gas station) 

Pond 

Stream 

Well (tap) 

Stream 

Well (hose) 



SOURCE: Citizen Alert, 1988 



underground nuclear testing program, this mistrust 
is exacerbated by tiie reluctance on the part of the 
Department of Energy to disclose information con- 



cerning the nuclear testing program, and by the 
knowledge that not all tests that release radioactive 
material to the atmosphere (whatever the amount or 
circumstances) are announced. This has led to 
allegations by critics of the testing program that: 

... the Energy Department is continuing its misin- 
formation campaign by refusing to disclose the size 
of most underground tests, by hushing up or 
downplaying problems that occur and by not an- 
nouncing most tests in advance, thereby leaving 
people downwind unprepared in the event of an 
accidental release of radioactive materials.'^ 

Such concern could be greatly mitigated if a 
policy were adopted such that all tests were an- 
nounced, or at least that all tests that released any 
radioactive material to the atmosphere (whatever the 
amount or circumstances) were announced. 



Figure 4-14 — Locations of Families in the Offsite Human Surveillance Program 



ft 



Pyramid Lake 



Nevada 



• Austin 



Ely 



% 

. Lund 




Salt 
Lake 



Salt Lake City 



Round Mt ooo Currant 
o 
Blue Jay o o Blue Eagle Ranch 

Tonopah ^^ ° Nyala Eagle Valley 



Goldfield 

Nevada 
Test 
Site 
Beatty 

^ . 
Lattirop Wells o 

Pahrump 
Shoshone* 



o Offsite Family 

• Community Monitoring Sta. Family 



Cedar City 




Bunkerville 
Indian overton 




About 40 families from around the test site are brought in to EPA twice a year for whole-body analysis. 

SOURCE: Modified from Environmental Protection Agency 



'^John Hanrahan. "Testing Underground," Common Cause. voL 15, No. I, January/February 1989. 



Chapter 4 — Monitoring Accidental Radiation Releases • 79 



Figure 4-15 — Well Sampling Locations Onsite 




Scale In Miles 
22 wells on the Nevada Test Site are sampled monthly. 
SOURCE: Modified from Department of Energy. 



80 • The Containment of Underground Nuclear Explosions 



Figure 4-16 — W^ll Sampling Locations Offslte 

Twin Springs Rn. • 

• Nyala 

• Adaven Springs 



Tonopah 



\ Goss Springs c _ 
\ •l1S/48-1dd 

N Beatty • •^ ,Younghans Ranch(2) 

\US Ecology. Specie Springs 

u 



\ 



• Tennpiute 
• Penoy8r(3) 




Crystal Springs 



VJusaf #2| 



Lathrop Wells • 

^ ^ » Fairbanks Springs 

Well 17S/50E-14CaC • . , , „ , 
\ • Crystal Pool 

Well 1 88/51 E-7db • 



u 



Indian Springs 
Sewer Co. Well 1 



Scale in l\^iles 
10 20 30 



40 



s^A, • Calvada Well 1 

• Shostione "^^ 
Spring 



Las Vegas 
well #28 

Lake Mead • 
Intake 



I II 11 

10 20 '30 I 40 50 60 
Scale in Kilometers 
31 wells around the Nevada Test Site are sampled twice a year. 

SOURCE: Modified from Department of Energy. 



Related OTA Report 

• Seismic Verification of Nuclear Testing Treaties. 

OTA-ISC-361. 5/88; 139 pages. GPO stock #052-003-01 108-5; $7.50. 
NTIS order #PB 88-214 853/XAB. 

NOTE: Repons arc available from the U.S. Govcmmcm Priming Office, Superintendent of Documents, Washington, D.C. 20402-9325 (202-783-3238); 
and the National Tfechnical Information Service, 5285 Port Royal Road. Springfield, VA 22161-0001 (703-487-4650). 



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Office of Technology Assessment 



The Office of Technology Assessment (OTA) was created in 1972 as an 
analytical arm of Congress. OTA's basic function is to help legislative policy- 
makers anticipate and plan for the consequences of technological changes and 
to examine the many ways, expected and unexpected, in which technology 
affects people's lives. The assessment of technology calls for exploration of 
the physical, biological, economic, social, and political impacts that can result 
from applications of scientific knowledge. OTA provides Congress with in- 
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Requests for studies are made by chairmen of standing committees of the 
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the Board. 

The Technology Assessment Board is composed of six members of the 
House, six members of the Senate, and the OTA Director, who is a non- 
voting member. 

OTA has studies under way in nine program areas: energy and materials; 
industry, technology, and employment; international security and commerce; 
biological applications; food and renewable resources; health; communication 
and information technologies; oceans and environment; and science, educa- 
tion, and transportation. 



OTA-ISC-414 OCTOBER 1989