A new direct external recycling concept for the tritium fuel cycle of CFETR

Tritium self-sustaining operation, which is achieved by a successful closed tritium fuel cycle, is one of the key scientific objectives of China Fusion Engineering Test Reactor (CFETR). The initial tritium start-up inventory and the required TBR are two key parameters which directly affect the possibility of achieving tritium self-sufficiency. In this paper, a new purge gas scheme of He + 0.n% vol. D2 is proposed for tritium extraction of solid breeder blanket, which can avoid the existence of protium in the mixed gas. In this way, the isotope separation system (ISS) in outer fuel cycle (OFC) can be omitted and a new concept of direct external recycling (DER) has been first put forward for OFC, which aims to skip ISS-O and reduce the processing time of OFC; and the feasibility of DER is preliminarily analyzed from four aspects. On this basis, the influences of DER on both the initial start-up inventory and the required TBR have been preliminarily analyzed for different fueling efficiency and tritium burning fraction (TBF) products, and the calculation results are compared with those corresponding to the same direct internal recycling (DIR) fractions. The results indicate that the application of DER can reduce the demand for both the initial start-up inventory and the required TBR, which can improve the possibility of achieving tritium self-sufficiency appropriately. In particular, the amount of “start-up inventory saved by DER” is still attractive under the condition of high fueling efficiency and TBF, and it is in direct proportion to the fusion power. Both of these make DER technology even more attractive for DEMO reactor and future power plant (FPP). These studies can provide some valuable suggestions for the design and optimization of the tritium fuel cycle system of CFETR and FPP.