SL-1– One of America’s Worst Nuclear Accidents

On 3rd January 1961 America suffered one of its worst nuclear accidents at the SL-1 experimental nuclear reactor at Idaho Falls, Idaho.

The accident killed the three men on duty, two almost immediately and one shortly after. The cause was a prompt criticality accident, a control rod in the reactor was removed too far causing a sudden surge in power.The power surge was later established to have jumped to 10 gigawatts in less than 4 milliseconds causing the water coolant surrounding the reactor core to form a water hammer and cause the entire pressure vessel, weighing 11.7 tonnes, to jump more than 9 feet.

The SL-1 disaster is important in many respects because it demonstrates human inability to confront the dangers of nuclear power, our creeping complacency towards the energy being unleashed and not to truly learn from these accidents.

In many respects SL-1 was an accident waiting to happen; the reactors were not inside true containment buildings, the reactor design allowed this accident to happen and its arguable whether the crew was experienced to enough to supervise the running of a nuclear reactor.

America, and most of the world’s nuclear powers had already experienced nuclear accidents before the one at SL-1. There was the disastrous fire at Pile no. 1 at Windscale in 1957 in the UK which revealed just how much wasn’t understood about nuclear power, there was also the Kyshtym disaster in the USSR when the cooling system for a tank of highly radioactive waste failed resulting in an explosion, also in 1957. Against this background of disasters, two young men in their mid 20s and a 22 year old trainee were allowed to operate the SL-1 reactor.

Further reading:

  • Idaho Falls: The Untold Story of America’s First Nuclear Accident, William McKeown (not strictly the “first” accident, a criticality accident killed Harry Daghlian in December 1945 with what became known as the “demon core”)
  • Final report of SL-1 recovery operation, General Electric Company Idaho Test Station SL-1 Project, U.S. Atomic Energy Commission. Idaho Operations Office
  • Video: SL-1 The Accident: Phases I and II, U.S. Atomic Energy Commission at the Internet Archive