Neutronics conceptual research on a hybrid blanket of china fusion engineering test reactor

Abstract The engineering concept research of China Fusion Engineering Test Reactor (CFETR) is underway. In order to achieve tritium self-sufficiency and lower tritium startup inventory, a fusion fission hybrid blanket scheme is proposed in this paper as a backup for the traditional pure fusion blanket concepts. In the hybrid blanket design, natural uranium is used as fuel, light water as coolant and Li4SiO4 as tritium breeder. MCORGS, a burnup code coupled by MCNP and ORIGENS, is used in burnup calculation. JMCT, a Joint Monte Carlo Transportation code developed by Institute of Applied Physics and Computational Mathematics, is used to crosscheck the MCNP results. One dimensional design and optimization is firstly made to propose a multi-layer alternate arrangement of fission zone and tritium breeding zone so as to maximum Tritium Breeding Ratio (TBR) and a moderate energy Multiplication (M). A 3D neutronics model of CFETR is converted from MCNP benchmark files to a GDML file which is used in JMCT. At the beginning of the core, TBR3D is 1.26 which is bigger than the max achievable TBR for pure fusion blanket (around 1.15), M is 3.18 which means the tritium startup inventory will be 3 times lower than the pure fusion blanket in case of a fixed blanket thermal power. After 12 years burnup with 200 MW fusion power, TBR and M will be 1.28 and 4.05 respectively. The hybrid system is in an ultra deep subcritical state, the effective multiplication constant varies from 0.161 to 0.227. If the natural uranium in fission zone is replaced by spent fuel or LEU, more higher TBR and M will be obtained.