Simulation Problems of Advanced LWRs

Abstract

The next generation of commercial nuclear power reactors is characterized by a new approach to achieving safety systems reliability. In contrast to current generation reactors these designs apply passive safety features that rely on gravity driven transfer processes or stored energy such as gas pressurized accumulators or electric batteries. This paper addresses the implication of the gravity driven transfer processes on current numerical capabilities to simulate the thermal- hydraulic system behavior of those designs during postulated accidents. Requirements for computational accuracy are discussed in view of the small driving forces and duration of transients being simulated. Also the problems of integrating the primary system analyses with containment analyses are addressed. The impact on next-generation full scope simulation is assessed from the standpoint of operator training and emergency preparedness. Finally, the role of fast computing and graphic display interfaces for analyses of passive designs is discussed. The overall requirements for an integral safety analyses package suited for advanced LWR analyses are summarized.