Validation study of SAS4A code for the unprotected loss-of-flow accident in an SFR

ナトリウム冷却高速炉のULOF事象に関するSAS4Aコードの妥当性確認に関する研究

石田 真也  ; 川田 賢一   ; 深野 義隆  

Ishida, Shinya; Kawada, Kenichi; Fukano, Yoshitaka

ナトリウム冷却高速炉の炉心損傷事故(CDA)の起因過程を評価する安全解析コードSAS4Aの客観的な検証の十分性を示すためにSAS4Aの検証にPIRT(Phenomena Identification and Ranking Table)手法を導入した。当該手法に基づいて、課題と検証の目的の明確化、対象施設とシナリオの選定、FOMと重要現象の選定を行い、解析モデルと試験の検討結果を併せて検証マトリクスを作成した。作成した検証マトリクスと試験解析の結果によって、起因過程評価に必要な解析モデルが不足なく検証されていることを示した。加えて、今回の検証マトリクスは各物理現象の関連性も含んだ総合的な検証となっているため、この検証マトリクスを用いた検証は高い信頼性を有する検証であると言える。すなわち、本研究によって、SAS4Aコードの信頼性を大きく向上させることができた。

The Phenomena Identification and Ranking Table (PIRT) approach was applied to the validation of SAS4A code in order to indicate the reliability of SAS4A code sufficiently and objectively. Based on this approach, issue and objective were clarified, plant design and scenario were defined, FOM and key phenomena were selected, and the code validation test matrix was completed with the results of investigation about analysis models and test cases. The results of the test analysis corresponding to this matrix show that the SAS4A models required for the IP evaluation were sufficiently validated. Furthermore, the validation with this matrix is highly reliable, since this matrix represents the comprehensive validation that also considers the relation between physical phenomena. In this study, the reliability and validity of SAS4A code were significantly enhanced by using PIRT approach to the sufficient level for CDA analyses in SFR.