1961 in Idaho

Stationary Low-Power Reactor Number One, also known as SL-1, initially the Argonne Low Power Reactor (ALPR), was a United States Army experimental nuclear reactor at the National Reactor Testing Station (NRTS) in Idaho about west of Idaho Falls, now the Idaho National Laboratory. It operated from 1958 to 1961, when an accidental explosion killed three plant operators, leading to changes in reactor design. This is the only U.S. reactor accident to have caused immediate deaths.