Development of transient behavior analysis code for metal fuel fast reactor during initiating phase of core disruptive accident

金属燃料高速炉の炉心損傷事故起因過程解析コードの開発

太田 宏一*; 尾形 孝成*; 山野 秀将   ; 二神 敏  ; 島田 貞衣*; 山田 由美*

Ota, Hirokazu*; Ogata, Takanari*; Yamano, Hidemasa; Futagami, Satoshi; Shimada, Sadae*; Yamada, Yumi*

The experimental analyses of the U-Pu-Zr fuel pin behavior during transient overpower (TOP) tests were performed by CANIS, and the residual cladding wall thickness and molten region of the fuel alloy after the tests, and the reactivity inserted by molten fuel extrusion before the fuel pin failure were compared with the experimental results. On the basis of these analysis results, detailed calculation models were developed for and implemented into CANIS to be made it possible to consider changes in the local properties of the fuel alloys due to redistribution of fuel constituents during steady-state irradiation and in the cladding thinning rate depending on the fuel-cladding interface temperature. The modified CANIS properly predicted fuel behavior and resulting reactivity changes before fuel pin failure in TOP events.