核融合原型炉における保守保全の考え方と課題
概要
In-vessel components (IVCs) such as blanket segments and divertor cassettes strongly receive neutron irradiation through high energy neutron (14.06 MeV) from fusion plasma. Therefore, a fusion DEMO plant requires a periodic replacement of IVCs. The dose rate of IVCs for DEMO is one order of magnitude higher than that for ITER. The JA DEMO also requires a five-year cooling time to reduce its dose rate to the level of ITER's dose rate. The maintenance scheme for DEMO requires the components to be replaced by using remote handling equipment. In DEMO plant, moreover, high dose area is expanded by the flow of the primary coolant which is activated by high energy neutron. Therefore, the radioprotection of the equipment in the plant is regarded as an important task for the DEMO plant operation. Some problems specific to a fusion DEMO plant for maintenance and preservation are reported.
