OVERVIEW OF IN-VESSEL RETENTION CONCEPT INVOLVING LEVEL OF PASSIVITY - WITH APPLICATION TO EVOLUTIONARY PRESSURIZED-WATER REACTOR DESIGN

In this work, one strategy of severe accident management, the applicab ility of the in-vessel retention (IVR) concept, which has been incorpo rated in passive type reactor designs, to evolutionary type reactor de signs, is examined with emphasis on the method of external reactor ves sel cooling (ERVC) to realize the IVR concept in view of two aspects: for the regulatory aspect, it is addressed in the context of the resol ution of the issue of cerium coolability; for the technical one, the r eliance on and the effectiveness of the IVR concept are mentioned. Add itionally, for the ERVC method to be better applied to designs of the evolutionary type reactor, the conditions to be met are pointed out in view of the technical aspect. Concerning the issue of cerium coolabil ity/quenchability, based on results of the review, plausible alternati ve strategies are proposed. According to the decision maker's risk beh avior, these would help materialize the conceptual design for evolutio nary type reactors, especially Korea Next Generation Reactors (KNGRs), which have been developing at the Korea Electric Power Research Insti tute (KEPRI): (Al) Strategy 1A: strategy based on the global approach using the reliance on the wet cavity method; (A2) Strategy 1B: strateg y based on the combined approach using both the reliance on the wet ca vity method and the countermeasures for preserving containment integri ty; (A3) Strategy 2A: strategy based on the global approach to the rel iance on the ERVC method; (A4) Strategy 2B: strategy based on the bala nced approach using both the reliance on the ERVC method and the count ermeasures for preserving containment integrity. Finally, in applicati on to an advanced pressurized water reactor (PWR) design, several reco mmendations are made in focusing on both monitoring the status of appr oaches and preparing countermeasures in regard to the regulatory and t he technical aspects. (C) 1998 Elsevier Science Ltd. All rights reserv ed.