Fuel Management Effects on Inherent Safety of Modular High Temperature Reactor

Analysis was performed on the effects of fuel loading schemes and fuel materials on the inherent (passive) safety characteristic of the modular pebble-bed type high-temperature reactor against depressurization accident involving loss of He forced circulation Two extreme fuel loading schemes, the infinite-velocity multipass and Once-Through-Then-Out (OTTO), were evaluated for both U and Th fuel cycles. The results of the analysis show that the maximum core temperatures attained following the accident were much lower for the infinite-velocity multipass scheme than for the OTTO scheme. For both schemes, the Th cycle showed slightly higher maximum peak temperatures, compared to U cycle.