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.

A new type of Water Lead Lithium Cooled (WLLC) blanket that adopts the modular design scheme, water cooling the structure components, liquid PbLi as breeder and coolant, and SiC as the thermal insulator between PbLi and structures is under development as a candidate blanket concept for the Chinese Fusion Engineering Test Reactor (CFETR). Based on a poloidal-radial slice model, thermal hydraulic analysis is performed for this blanket to validate the feasibility of design goals. Results show that the present design can achieve the outlet temperature in the range of 600–700 °C, with all the material temperatures safely below the upper limits. A series of sensitivity analyses are also carried out. It indicates that the thermal conductivity (TC) of SiC would have a significant influence on the temperature field, streamlines and pressure drop; that is, lower TC of SiC can maintain the temperature of PbLi at a high level, and induce an increased number of vortices in the liquid PbLi flow as well as a larger pressure drop. On this basis, the joint effects of the TC of SiC and inlet velocity on the performance of blanket thermal hydraulics are analyzed, then the so-called “attainable region” is proposed. Finally, optimization design studies are carried out by decreasing the width of the front channel. Comparison results show that the present design is the most reasonable.