METHODOLOGY TO ASCERTAIN CORE RECRITICALITY FOLLOWING A SEVERE FISSION REACTOR ACCIDENT

摘要

Recriticality concerns have been expressed following severe power reactor accidents, involving fuel melting and possible core relocation out of the reactor vessel. Analyses of reactor coolant liquid samples must carefully evaluate fission isotope activities when assessing the possibility of a recriticality. Assessments should consider the criticality duration, sampling time, sampling location, and core operating history to provide an accurate determination of a recriticality. By considering these factors, the ~(131)I/~(137)Cs activity ratio can lead to a determination if a recriticality occurred.