Thermal–Hydraulic Analysis for One Water-Cooled Blanket Module of CFETR Based on RELAP5

The water-cooled ceramic breeder blanket (WCCB) is one of the blanket candidates for the Chinese fusion engineering test reactor (CFETR). The conceptual of WCCB for CFETR under 200-MW fusion power has been designed based on pressurized water-cooled reactor technology. RELAP5 code, which is mature and often used in transient thermal-hydraulic analysis in pressurized water reactor, was selected as the simulation tool. In this paper, the nodal model for RELAP5 was developed corresponding to typical WCCB module, i.e., the coolant passages inside the module were nodalized as hydrodynamic components, and the associated module components were simulated with 1-D heat structures. The steady-state characteristic under full power was analyzed. The stable fluid, wall temperature distributions, and pressure drops were studied. The results were compared with those of the 2-D and 3-D computational fluid dynamics analyses by FLUENT. Furthermore, the transient characteristics under three accidental scenarios, in-vessel loss of coolant accident (LOCA), in-box LOCA, and ex-vessel LOCA, were analyzed, respectively. Simulation results show that the cooling of stiffening plates and side walls for breeder zone is very important for the blanket module. All the pressurization of the related volumes is within the design limits. The temperature of the structures does not exceed the limits for a relatively long time that allows mitigation measures to be taken. As for in-box LOCA, the exclusion of Be-water reaction makes the temperature nonconservative and still needs further study.