Development of PWR power-generating plants and the review

On the standpoint of the designer of PWR plants, the progress and the present state of the development of PWRs in Japan are outlined. PWR is the reactor type, the large commercial machines of which were first put in practical use, because it has been developed energetically as it is relatively easy to handle with conventional technologies in the principle and the design. The trend of advancing to large capacity is shown chronologically. In Japan, Mitsubishi group contracted the technical tie-up with Westinghouse and started the manufacture and sale of POR power-generating plants. In June, 1977, 6 units are in operation, 5 units are under construction, and 3 units are in safety deliberation stage. The design and manufacture technologies for PWRs in Japan were able to reach the world level in very short period. The main components of the steam-generating installation for PWR plants are the reactor vessel, coolant-circulating pumps, steam generators, the pressurizer, and coolant pipings. The efforts of improvement must be exerted to raise the rate of operation and reliability of plants, to make inspection, security and maintenance precise, to reduce the radiation exposure of workers, and to shorten the period of construction and repair. Especially, reactor containment vessels are explained. New construction sites, such as underground plants and offshore plants, are being investigated. (Kako, I.)