There is no doubt whatsoever that the operators were not at fault. The cause of the failure was due primarily to "several" serious design flaws that could allow the reactor to almost instantly become catastrophically and explosively super-critical with the extraction of A SINGLE control rod past its maximum specified limits.

Considering the maintenance history and records of "sticky" control rods its very likely that during maintenance the operators accidentily jarred loose a rod trying to free it. The design of the reactor was such that within 14mS of this the reactor instantly pulsed up to 20GigaW and they were dead or dying. No chance ever to recover and correct from a simple error.

All reactors of this type were then modified to inherently restrict control rods from being pulled past the design limit so this could never happen again.

These poor buggers died because serious design flaw wasnt remedied or controlled. A lesson to us all.

http://en.wikipedia.org/wiki/SL-1

While it's true this film is quite open and detailed, it was not declassified for more than 20 years after the incident. The fact that it is "revealing" means nothing in that it wasn't made public at the time of the incident.

Considering the time -- the 1950s -- this film report is exceptionally candid about the vulnerabilities of nuclear reactors. This first civilian reactor accident was especially gruesome in that one of the reactor operators was shot into the ceiling by an expelled reactor vessel plug and control rod. Views of the internal wreckage are fascinating. The cause of this accident has never been determined, although operator error has been alleged -- even a possible suicide by one of the operators.
Documentaries of this quality are rare in the U.S. nuclear community, at least for the general public.