| 内容記述 | The present report discusses the current understanding and improved evaluation method of key phenomena in the initiating-phase energetics of ULOF whole-core accidents in LMFBRs. Three phenomena, i.e. axial fuel expansion, fuel failure and post-failure fuel motion, have been examined through the CABRI-1 in-pile tests and analyses with special emphasis on the mechanisms for self-limiting the energetics potential. Major important mechanisms, identified in this study, are: (1) fuel expansion effective to delay the ULOF-induced power burst; (2) fuel-dispersal potential activated under low energy condition in voided channels, and enhanced fuel mobility with increased heating rate; (3) above-midplane failure and failure extension effective particularly in partially voided channels. The improved knowledge validated through the CABRI-1 analyses has been implemented to the revised SAS3D code as an improved evaluation method of CDAs, and the importance and effectiveness of the mechanisms were confirmed by the reactor application study.
著者所属: 日本原子力研究開発機構(JAEA) |
