A real-time prediction technique of severe accident progression in containment for emergency response

A computerized support system for the emergency technical advisory body (ETAB) in Japan (COSTA) is being developed by the Japan Atomic Energy Research Institute to provide useful information for the ETAB during a reactor accident emergency. A major function of COSTA is to identify plant status and predict accident progression in real time based on emergency data reported by the utility of the affected plant. This function could not be achieved if severe accident analysis codes are used directly because the use of these codes would take extensive computing time. This paper describes a real-time prediction technique for accident progression in a PWR containment during a severe accident when water on the containment floor flows into the reactor cavity (wet cavity). The technique developed combines a knowledge-based expert system with a multivariate analysis method, which makes it possible to predict accident progression in real time and to quickly cope with changing emergency situations. The results predicted with this technique was compared with the results by two severe accident analysis codes, THALES and STCP, and the technique reproduced well the results by the codes. (author)