B-10 Influence on Fuel Burnup in UN-UB2 High Density Fuels

Addition of UB2 to UN fuel increases the onset temperature of reaction with high temperature steam in LWR environments. Natural boron contains 19.9% of B-10, a strong neutron absorber which upon neutron absorption decays to Li-7 and He-4. The work investigates potential of UN-UB2 (10% UB2) with varied B-10 concentration as nuclear fuels. A range of B-10 concentration from 0-19.9% B-10 is considered. An infinite LWR fuel lattice is used to explore this. Depletion analysis of UN-UB2 fuels and UO2 fuel are carried out. The performance is compared on potential cycle length and fuel burnup. UN-UB2 (1% B-10) fuel was observed to feature comparable cycle length to UO2 and UN-UB2 (0% B-10). UN-UB2 (1% B-10) fuel observed to feature lower reactivity span over potential lifetime due to burnable poison effect of B-10. Fuel composition analysis explored evolution of UN-UB2 composition with burnup. Calculated total amount of noble gases at 1500 EFPD for UN-UB2 (1% B-10) was comparable to that of UO2, with amount of helium in UN-UB2 (1% B-10) comparable to that of krypton in UO2 fuel. The findings suggest that UN-UB2 (1% B-10) composite fuels can provide comparable performance to UO2 with higher thermal conductivity, manageable helium generation, and effective reactivity control, making them a promising candidate of LWR fuels.