Burnup calculation of fusion–fission hybrid energy system with thorium cycle

A fusion–fission hybrid reactor which is a fusion reactor with a blanket region containing nuclear fuel. In our group, a calculation system for analysis of fusion–fission hybrid reactor has been developed and various transport and burnup calculations were carried out for hybrid systems with U–Pu fuel cycle and ITER model so far. It was confirmed that such system is feasible and even beneficial. However, there is difficulty to hold down the production rate of minor actinides. Thus, the study of fusion–fission hybrid energy system with Th–U fuel cycle was performed. The calculations for hybrid system with U–Pu fuel cycle were carried out again because of development of the calculation system. As a result of analysis, a fusion–fission hybrid system with thorium fuel cycle meets requirements which include self-sufficiency of tritium, subcriticality of the system and acceptable cooling capability. In comparison with U–Pu cycle, the production rate of minor actinides of Th–U fuel cycle is generally lower than that of U–Pu cycle as expected. In addition, we investigated two different coolants of helium gas and water. The water-cooled blanket is suitable for energy generation. On the other hand, gas-cooled blanket has an advantage in FP transmutation.