DEVELOPMENT OF A PHENOMENA IDENTIFICATION RANKING TABLE FOR A STATION BLACKOUT ACCIDENT OF THE PRESSURIZED WATER REACTOR

摘要

A station blackout (SBO) is one of the most important design extension conditions (DECs) in that without any proper operator actions, a total loss of heat sink leads to core uncovery, to core damage, and ultimately a core melt-down scenario under high pressure. Due to this safety importance, a SBO is considered to be a base test item of the OECD-ATLAS project. In order to simulate a SBO transient in a thermal-hydraulic integral effect test as realistically as possible, the expected thermal-hydraulic phenomena should be precisely examined in advance. In this study, a Phenomena Identification Ranking Table (PIRT) has been developed for identifying the major parameters affecting the thermal-hydraulic phenomena in SBO transients. Development of PIRT for SBO transient is expected to contribute to making strategy for performing a thermal-hydraulic integral effect test with ATLAS which includes determination of proper test conditions and improvement of measurements. As for the major components of the nuclear power plant, the rank of the importance and the knowledge level were summarized for each of the three temporal phases. Taking into account the important phenomena from the PIRT result, it can be confirmed that ATLAS has a capability of simulating the major thermal-hydraulic phenomena during a SBO transient as realistically as possible.