Preliminary evaluation of decay heat in a HCPB DEMO fusion reactor

*In previous studies, energy generation in a fusion DEMO reactor was estimated by accounting for prompt heat production only, neglecting the decay heat generated from the decay of radioactive isotopes. In this work, based on a helium-cooled pebble bed (HCPB) ceramic blanket which is one of the European DEMO concepts, the decay heat generated in different components is estimated as a function of cooling time is performed in order to assess its contribution. The code system HERCULES, by coupling the MCNP particle transport and the activation inventory FISPACT, is used for the calculation of prompt energy deposition and decay heat for all components in the HCPB DEMO reactor. It is found that, relative to fusion power of 2.7GW, the activated nuclides generated decay heat are <3% at the cooling time of 1 second assuming a power plant operation scenarios. This study suggests that the material selection has a significant impact on decay heat.