Construction of Sodium-cooled Medium-scale Modular Reactor in Consideration of In-service Inspection and Repair

Hishida, Masahiko; Konomura, Mamoru; Uchita, Masato; Iitsuka, Toru*; Kamishima, Yoshio*

An innovative concept of medium-scale sodium-cooled modular reactor, named M-JSFR, has been created as based on the large-scale advanced loop type fast reactor concept. M-JSFR employs other concepts such as standardization and learning effects by designing as a modular plant and reduction of secondary loop number for the purpose of dissolving the scale-demerit. On this M-JSFR, some improvements are performed to overcome the weak point (strong chemical activity of sodium) of a sodium-cooled reactor and to achieve in-service inspection (ISI) and repair as easily as in light water reactors. Based on the ISI guidelines for light water reactors, the ISI procedures are reviewed reflecting the characteristics of M-JSFR. A guideline for ISI with the same grade of that of the light water reactors is established and major components subjected to ISI are selected. Moreover, suitable ISI procedures for each selected major component are proposed, and a plant concept amenable to ISI is studied. As the result of these studies, the construction cost of ISI&R reinforcement M-JSFR increases about 3% mainly because of the diameter expansion of reactor vessel.