SL-1 Nuclear Reactor Incident.

On December 21, 1960, the reactor was shut down for maintenance, instrument calibration, installation of auxiliary instruments, and installation of 44 flux cables to control neutron flux levels in the reactor core. The cables were made of aluminum with incorporation of aluminum-cobalt alloy. At 9:01 p.m. m. On January 3, 1961, after an 11-day closure for vacations, and during maintenance actions, the SL-1 went into immediate crisis. As a result, the large amount of heat generated in just 4 milliseconds caused the sudden evaporation of part of the water in the reactor core. The water vapor generated caused a pressure wave that hit the top of the reactor hull. This pushed the control bar and the entire reactor hull upward, killing the operator on top of the hull, leaving him stamped on the roof. Two other military employees, a supervisor and a trainee, were also killed. The victims were Army Specialists John Byrnes, Richard McKinley and Chief Navy Electrician Mate Richard Legg.