Development of passive safety systems for next generation PWR in Japan

Our country's energy demand is expected to increase steadily into the futur e. When the situation of our country, which is not rich in energy resources , is taken into account, it seems that the importance of nuclear power gene ration will be heightened. Based on such a background, the basic policy for nuclear power generation is 'from light water reactors to fast breeder rea ctors'. However, considering that light water reactors have become common, the recent outlook for the supply and demand for uranium resources, develop ment trends of fast breeder reactor technology, etc., the light water react or is expected to remain dominant in our country until at least the second half of the 21st century. Therefore, five PWR utilities in Japan (Hokkaido, Kansai, Shikoku, Kyushu, and Japan Atomic Power), Mitsubishi Heavy Industr ies Ltd and Westinghouse Electric Corporation have jointly started research ing the Next Generation PWR (N.G.P) which is expected to be the leading nuc lear power plant, taking place of APWR ET. Magari, Development of Next Gene ration PWR in Japan, Proceedings of the 10th Pacific Basin Nuclear Conferen ce, 1996; K. Fujimura, et al., Proceedings of the Second International Symp osium on Global Environment and Nuclear Energy Systems, 1996]. In this prog ram, construction is targeted to start from 2010 based on expected future e nvironmental conditions. Now, the capacity of more than 1500 MWe class PWR concept is investigated and a plant concept which has innovative features o f a hybrid safety systems, i.e. an optimum combination of active and passiv e safety systems, and horizontal steam generators for core cooling at the a ccidents is developed as a promising candidate. The plant concept and the r esults of the investigation are presented in this paper. (C) 2000 Elsevier Science S.A. All rights reserved.