Conceptual Design Study of Small Sized Sodium Cooled Reactor

Usui, Shinichi; Chikazawa, Yoshitaka; Konomura, Mamoru; Tanaka, Toshihiko; Hori, Toru*; Ohkubo, Toshiyuki*

Proceedings of 2005 International Congress on Advances in Nuclear Power Plants (ICAPP '05) (CD-ROM), 0 Pages, 2005/05

The Japan Nuclear Cycle Development Institute and the Electric Utilities have been studying for concepts of commercialized FBR plant system. In this study, a small sized sodium cooled reactor has been studied from standpoints of having a potential to use a power source applicable to diversified social needs and reduced capital risks. The concept is pursued to satisfy various requirements: economical competitiveness, reactor safety, very long lived core, etc. The electrical power is set to 165 MWe based on previous studies of small sized sodium cooled reactor which was aim of cost reduction of the plant pursued. A three regional Zr concentration with one Pu enrichment core has been designed. The burn-up reactivity is kept 1.17% dk/k and the core refueling occurs after 20 years operation with 77,000 MWd/t average burn-up. The reactor system is enhanced a passive safety to avoid a core melt even an ATWS and the design has possible capability to withstand UTOP and ULOHS events, although it requires reactor shutdown action by operator within a certain time. Tank-type primary system has been designed. A circular type IHX and a primary EMP are located in series inside of the reactor vessel. The steam generator and the secondary EMP are located outside of the reactor vessel and connected to the IHX by piping. A diameter of the core is minimized in order to reduce a reactor vessel size. Two PRACS driven by natural circulation is chosen as a decay heat removal system in order to satisfy a heat removal condition of Category IV in Japanese standard.The construction cost of the whole plant evaluates to be achieved an economical goal considering a mass production.