Evaluation on Differences of Fuel Centerline Temperatures of High Performance Fuel Rods Irradiated in JMTR

This study is based on the fuel centerline temperature measurement conducted in the Japan Materials Testing Reactor (JMTR). The specimen used In this experiment is the assembly composed of three fuel rods, two high performance fuel rods (one has the Cu-barrier cladding and the other has the Zr-liner cladding) and one reference fuel rod (i.e. it has the normal cladding). As to the fuel centerline temperature, it was investigated whether there are (1) differences between the reference fuel rod and the high performance fuel rods and (2) differences between two high performance fuel rods. Consequently, the differences of the fuel centerline temperatures were obvious among three fuel rods. And it was concluded that the inside surface roughness of the cladding of the fuel rods have the important effect on the differences of their fuel centerline temperatures because the fuel centerline temperature of the fuel rod with the Zr-liner cladding of which the inside surface is rougher than that of the normal cladding is higher than that of the fuel rod with the normal cladding etc.