DEVELOPMENT OF TRANSIENT BEHAVIOR ANALYSIS CODE FOR METAL FUEL FAST REACTOR DURING INITIATING PHASE OF CORE DISRUPTIVE ACCIDENT

抄録

The experimental analyses of the U–Pu–Zr fuel pin behavior during transient overpower (TOP) tests were performed using CANIS, and the residual cladding wall thickness, 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 experimental results. On the basis of the obtained analysis results, detailed calculation models were developed to make it possible to reflect changes in the local properties of the fuel alloys due to the redistribution of fuel constituents during steady-state irradiation and in cladding thinning rate depending on the fuel–cladding interface temperature. With such calculation models implemented, CANIS properly predicted fuel behavior and resulting reactivity changes before fuel pin failure in TOP events.