A Methodology for Assessment of External Vessel Cooling During Severe Accidents in PWRs

摘要

A probabilistic methodology has been developed for feasibility evaluation of in-vessel retention of the molten corium through external reactor vessel cooling (IVR-ERVC) during severe accidents of pressurized water reactors. It estimates the overall success probability of the IVR-ERVC from the viewpoint of thermal failure by combining the results of Level-1 probabilistic safety assessment, a critical heat flux correlation, and wall heat flux distributions calculated by a severe accident code with appropriate adjustment. The practicability of the proposed approach is verified with a preliminary application to the Korean Standard Nuclear Power Plant. This paper also discusses future developmental needs for more reliable assessment.