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Nakamura, Hironori*; Hayakawa, Satoshi*; Shibata, Akihiro*; Sasa, Kyohei*; Yamano, Hidemasa; Kubo, Shigenobu
Proceedings of 12th Japan-Korea Symposium on Nuclear Thermal Hydraulics and Safety (NTHAS12) (Internet), 7 Pages, 2022/10
In order to evaluate long-term coolablity of the debris-bed with decay heat, a three-dimensional calculation method coupled with the debris bed module was developed in this study. The coupled code calculation results show that natural circulation of the coolant between the hot pool and the cold pool is established through the four intermediate heat exchangers after the activation of the dipped direct heat exchangers. The cold pool with the debris-bed is continually cooled not only by the natural circulation flow, but also by heat transfer to the hot pool through the plenum separation plate between the hot pool and the cold pool. The effect of the three-dimensional flow field around the core catcher on the temperature in the debris-bed is about 20K under the current calculation condition.
Yamano, Hidemasa; Kubo, Shigenobu; Kan, Taro*; Shibata, Akihiro*; Hourcade, E.*; Dirat, J. F.*
Proceedings of 29th International Conference on Nuclear Engineering (ICONE 29) (Internet), 10 Pages, 2022/08
In this paper, the approach to event tree development and the scope of the event tree analysis were described with key points on core catcher loading. For the analytical conditions, two core catcher loading conditions were given as bounding and conservative cases. For important heading of the event tree, key important phenomena were included: strong back design, fuel-coolant interaction and quench in the sodium plenum design, jet attack, criticality and coolability on the core catcher. In this paper, preliminary trial quantification was attempted using a probability ranking table which is based on engineering judgement. This event tree analysis has identified the dominant sequence, and clarified the effect of the core catcher loading and effectiveness of design measures. This study suggests that the criticality measure is very important for the core catcher study.
Yamano, Hidemasa; Kubo, Shigenobu; Sasa, Kyohei*; Shibata, Akihiro*; Hourcade, E.*; Dirat, J. F.*
Proceedings of 29th International Conference on Nuclear Engineering (ICONE 29) (Internet), 9 Pages, 2022/08
This paper describes coolability evaluations of a debris bed with a variety of decay heat removal system (DHRS) operating conditions with a whole vessel model assuming fuel accumulation on the core catcher in a short term. The evaluation tool is a one-dimensional plant dynamics code, Super-COPD, with a debris bed module. The coolability evaluations have indicated that the current core catcher design secures sufficient natural circulation flows around the core catcher to ensure the debris bed cooling when at least one circuit of DHRS was activated. Sensitivity analyses under a pessimistic condition have shown that the debris bed is coolable with at least one circuit of improved DHRS even if most of fuel accumulates on the core catcher in a short term.
Kubo, Shigenobu; Payot, F.*; Yamano, Hidemasa; Bertrand, F.*; Bachrata, A.*; Saas, L.*; Journeau, C.*; Gosse, S.*; Quaini, A.*; Shibata, Akihiro*; et al.
Proceedings of International Conference on Fast Reactors and Related Fuel Cycles; Sustainable Clean Energy for the Future (FR22) (Internet), 8 Pages, 2022/04
Kato, Atsushi; Ide, Akihiro*; Shibata, Akihiro*; Ishizaki, Miku*; Tanaka, Futoshi*; Sakaba, Hiroshi*; Nishizaki, Chihiro*; Sawairi, Tsuyoshi*
no journal, ,
Sodium fast reactor needs long time decay heat removal compared with Light water reactor. This reports trial evaluation of dynamic PRA application on Sodium cooled fast reactor in terms of decay heat. Thanks to this application, dominant risk factor could be cleared out.
Shibata, Akihiro*; Kubo, Shigenobu
no journal, ,
no abstracts in English
Nakamura, Hironori*; Shibata, Akihiro*; Hayakawa, Satoshi*; Yamano, Hidemasa; Kubo, Shigenobu
no journal, ,
The coolablity of the debris-bed on a core catcher was evaluated using a three-dimensional CFD code coupled with the debris bed module in this study. The coupled code calculation results showed the prospect to attain a long-term stable cooling.
Kubo, Shigenobu; Higurashi, Koichi*; Shibata, Akihiro*
no journal, ,
This paper describes progress of pool-type next generation sodium-cooled fast reactor (SFR) design study in Japan. Safety design criteria and safety design guidelines for SFR developed in the frame of generation IV international forum are fully applied in the safety design. In order to eliminate complete loss of heat removal, decay heat removal facilities are enhanced and their performance is evaluated.