SL-1
The SL-1 was an experimental military nuclear power reactor; its full name was the Stationary Low-Power Reactor Number One. Its original designation was ALPR, the Argonne Low Power Reactor. It was designed to provide electrical power and heat for small, remote military facilities, such as radar sites near the Arctic Circle. It was located approximately forty miles west of Idaho Falls, Idaho, in the National Reactor Testing Station.At 9:01 pm on January 3, 1961, during maintenance procedures, the SL-1 went prompt critical. In four milliseconds, the heat generated by the resulting enormous power surge caused water surrounding the core to explosively vaporize, killing three military personnel who were supervising restart operations, after a shutdown of eleven days for the holidays.
One of the required maintenance procedure called for the main control rod to be manually withdrawn approximately three inches in order to attach it to its automated control mechanism, from which it had been disconnected. Post accident calculations estimate that the main control rod was actually withdrawn approximately twenty inches, causing the steam explosion. The three most common theories proposed for this discrepancy are sabotage by one of the operators, inadvertent withdrawl of the main control rod, which was known to be "sticky," or an intentional attempt to "exercise" the sticky rod, to make it travel more smoothly within its sheath. The maintenance logs do not address what the technicians were attempting to do and thus the actual cause of the accident is unlikely to ever be known.
The remains of the SL-1 reactor are now buried near the original site of the reactor.
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