Abstract
Safety demonstration tests using the High Temperature Engineering Test Reactor (HTTR) are in progress to demonstrate the excellent inherent safety features of the High Temperature Gas-cooled Reactors (HTGRs), to improve the safety design and to evaluate the technologies for HTGRs. The coolant flow reduction test by tripping one or two out of three gas circulators is one of the safety demonstration tests. The reactor power safely brings to a stable level without a reactor scram and the temperature transient of the in-core is very slow. Through the safety demonstration test, the temperature transient analysis code (TAC-NC code) is improved. This paper describes the validation of the TAC-NC code using the measured value of the test by tripping of one and two out of three gas circulators at 30% (9MW). By upgrading the code, the analytical model can evaluate accurately the transient temperature distribution of the in-core within 20°C during the test. Through the temperature transient analysis by the improved code, it was confirmed that the reactor became stable safely without fuel temperature rise during all gas circulators stop test planned as near future safety demonstration test. The result of this study can be applied to development for not only the commercial HTGRs but also the Very High Temperature Reactor (VHTR) such as one of the Generation IV reactors.
