Cecil Kelley criticality accident

The Cecil Kelley criticality accident occurred on April 20, 1960, at the Los Alamos National Laboratory in New Mexico. This incident involved a criticality excursion—an uncontrolled chain reaction involving fissile materials, specifically uranium-235. Cecil Kelley, a laboratory employee, was working with a solution of enriched uranium when he inadvertently caused a criticality event. The conditions he created led to a neutron chain reaction that released a significant amount of radiation.