Thermal-Hydraulic Analysis of Design Basis Accidents for Chinese Helium-Cooled Solid Breeder TBM

Based on the structural design of the Chinese Helium Cooled Solid Breeder (CH HCSB) test blanket module (TBM), the thermal-hydraulic behavior and safety performance of the CH HCSB TBM cooling system has been studied using the RELAP5/Mod3.4 code. According to the accident sequences of Accident Analysis Specification for TBM, two design basis accidents including loss of off-site power and multiple TBM FW (first wall) HTS (heat transfer system) pipe failure are investigated. The results show that natural circulation is established in the helium cooling circuit to cool the TBM effectively after loss of off-site power. In addition, after multiple TBM FW HTS pipe failure, the TBM can be cooled down because of the thermal radiation. The maximum vacuum vessel (VV) pressure and the mass of not condensable gas spilling into the VV are within the limits for ITER design. Temperature difference between the break and intact FW pipes is also found.