Conductive inserts to reduce nuclear fuel temperature

Abstract

In an effort to develop better performing nuclear fuels, placement of conductive inserts in nuclear fuel pellets is being considered. Conductive inserts incorporated in the fuel pellets will dissipate heat more efficiently, allowing the fuel to operate at a lower temperature while producing the same amount of power. Calculation results reported in the present paper, show that placing a 6-finned molybdenum insert in a UO2 pellet will result in an 842 C reduction of the peak fuel temperature. Likewise, placing multiple equidistantly spaced 50 μm thick molybdenum discs in a UO2 pellet will result in a 995 C reduction of the peak fuel temperature. In both cases, the volume of the insert is limited to 5% of the volume of the pellet. While these results are preliminary in scope, the impact of the reduced peak temperature on expected fuel performance warrants initiation of experimental work that will include fabrication and irradiation of these and similar fuel designs at the Idaho National Laboratory.