Safety evaluation on the depressurization accident in the Gas Turbine High Temperature Reactor (GTHTR300)

Katanishi, Shoji; Kunitomi, Kazuhiko 

One of the unique safety design concepts of a Gas Turbine High Temperature Reactor (GTHTR300) is that events with frequency of occurrence of higher than 10/reactor-year are evaluated as design basis events (DBEs) in order to show that the frequency of large amount of FP release is less than 10/reactor-year. According to this concept, a depressurization accident is postulated as a DBE. This accident is one of the most serious accidents in the high temperature gas-cooled reactors from the view point of loss of coolability. The safety evaluation on the accident was conducted based on the actual design of the system. The fuel temperature behavior, internal pressure of the reactor building, oxidation behavior of fuels and graphite structures were evaluated and exposure dose of general public was also estimated using the results of evaluations of temperature and fuel failure. All of the results meet the safety criteria and feasibility of the GTHTR300 was shown by this study.