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Kurisaka, Kenichi; Kani, Yoshio
PNC TN9410 97-050, 127 Pages, 1997/05
In order to make a fast breeder reactor (FBR) practicable, it is important to make rational categorization of a safety design evaluation event. In this study, for the purpose of providing usefull information into the event categorization, we developed the occurrence frequency data of various abnormal events, presenteda proposal of the event categorization primarily based on the occurrence frequency and examined efficiency of the proposal. We researched and analyzed abnormal event instances of foreign and domestic FBR plants and of domestic light water reactor power plants. On the basis of the analysis, the failure occurrence frequency of the protection system (PS) in the FBR model plants with electric power production of 600MW and 1,000MW was quantified. Making use of results of probabilistic safety assessment study, loss-of-function probability of the mitigation system (MS) was quantified. Some of combinations of PS failure and loss of MS function were selected and their occurrence frequencies were quantified. We examined problems in the current categorization of the safety design evaluation event and presented a new proposal of the event categorization. Merits of the new proposal are to have divided the current category of "accident" into "small accident" and "rare accident", explicitly to treat a multiple failure event not as a collateral analysis condition of supposing "a single failure" but as an event to be evaluated, and to have added a category for the event which is beyond design base, but should be supposed to evaluate depth of the safety design in terms of defense-in-depth. Some candidates ofthe safety design evaluation event were identified and applied to the new proposal. In comparison with the current categorization, we obtained perspective that it was possible to evaluate the safety design more in detail and effectively, especially depth of the safety design such as backup reactor shutdown system, decay heat removal function in a natural ...
Nakai, Ryodai; Hioki, Kazumasa; Sakuma, Takashi; Kani, Yoshio
PNC TN9410 91-335, 62 Pages, 1991/10
Reliabilities of systems and components for LMFBR have been analyzed using CREDO (Centralized Reliability Data Organization) database in order to study the safety design of a large scale FBR based on the operational experiences of LMFBRs. In order to understand the characteristics of FBR-specific components, the comparison of reliabilities between safety and non-safety class components, and the trend of reliabilities on design parameter are evaluated. Based on the component reliability under various operating conditions, the deterministic requirements such as single failure criteria and testing effects are examined using a probabilistic technique. A quantitative technical basis is constructed to study an appropriate safety design policy. Reliabilities of a decay heat removal system are analyzed for various system configurations and success criteria. The dominant contributors to system unreliability such as the importance of support system under a forced circulation and the effectiveness of natural circulation are identified to develop the rational measures for reliability improvement.
Maruyama, Akira; Nomura, Shigeo; Kawai, Masashi; Takani, Satoru; Ota, Yoshio; Atsumo, Hideo
Nihon Genshiryoku Gakkai-Shi, 26(4), p.327 - 338, 1984/04
Times Cited Count：5 Percentile：51.26(Nuclear Science & Technology)None
Nakai, Ryodai; Saito, Shinzo; Yamaguchi, Akira*; Okamoto, Koji*; Kani, Yoshio*
no journal, ,
In response to the lessons learned from the serious nuclear accidents at the TEPCO's Fukushima Daiichi Nuclear Power Stations, the report "Safety Requirements Expected to the Prototype Fast Breeder Reactor Monju" was issued taking into account the SFR specific safety characteristics. The report was reviewed by the leading international and domestic experts on SFR safety in order to obtain independent and objective evaluation. As a result the basic concept for prevention of severe accidents and mitigation of their consequences of Monju is appropriate in consideration of SFR specific safety characteristics, and is in accordance with international common understanding.
