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Science and Technology of Nuclear Installations
Volume 2012, Article ID 614973, 14 pages
http://dx.doi.org/10.1155/2012/614973
Research Article

Safety Design and Evaluation in a Large-Scale Japan Sodium-Cooled Fast Reactor

1FBR Safety Unit, Advanced Nuclear System R&D Directorate, Japan Atomic Energy Agency, 4002 Narita-cho, O-arai, Ibaraki 311-1393, Japan
2Research and Development Department, Japan Atomic Power Company, 1-1 Kanda-Mitoshiro, Chiyoda-ku, Tokyo 101-0053, Japan
3Reactor Core and Safety Design Department, Mitsubishi FBR Systems, Inc., 2-34-17, Jingumae, Shibuya-ku, Tokyo 150-0001, Japan

Received 16 January 2012; Accepted 20 March 2012

Academic Editor: Sunil S. Chirayath

Copyright © 2012 H. Yamano et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

As a next-generation plant, a large-scale Japan sodium-cooled fast reactor (JSFR) adopts a number of innovative technologies in order to achieve economic competitiveness, enhanced reliability, and safety. This paper describes safety requirements for JSFR conformed to the defense-in-depth principle in IAEA. Specific design features of JSFR are a passive reactor shutdown system and a recriticality-free concept against anticipated transients without scram (ATWS) in design extension conditions (DECs). A fully passive decay heat removal system with natural circulation is also introduced for design-basis events (DBEs) and DECs. In this paper, the safety design accommodation in JSFR was validated by safety analyses for representative DBEs: primary pump seizure and long-term loss-of-offsite power accidents. The safety analysis also showed the effectiveness of the passive shutdown system against a typical ATWS. Severe accident analysis supported by safety experiments and phenomenological consideration led to the feasibility of in-vessel retention without energetic recriticality. Moreover, a probabilistic safety assessment indicated to satisfy the risk target.