The containment vessel is designed to contain the energy and radioactivematerials which would result from the postulated loss-of-coolant accident (LOCA)and to ensure a high degree of leak tightness during normal operation and underaccident conditions. Mitsubishi has taken part in the design, manufacture andconstruction of a large number of very successful nuclear power plants includingcontainments. In Japan, twenty seven BWRs (Boiling Water Reactors) and twentytwo PWRs (Pressurized Water Reactors) are in commercial operation. Mitsubishihas been engaged in nuclear business, especially in PWRs, for more than threedecades As shown in Figure 1 and Table 1, 22 PWR plants are in operation and 1PWR plant is under construction at 8 sites in Japan. Three PWR plants are in theplanning stage. In this paper, the containments of Japanese PWRs are discussed. Yushihisa Yamura; Mitsubishi Heavy Industries, Ltd.
