The Application of U-Np Fuel and ⁶Li Burnable Poison for Space Reactors

The possible application of ⁶Li as a burnable poison and U-Np nitride as a fuel for space nuclear reactors has been studied. The analysis was performed for an infinite lattice with a leakage in the form of buckling and (U-Np)N fuel with 20% uranium enrichment. The combination of ⁷Li as a coolant and ⁶Li as a burnable poison results in a favorable criticality behavior during burnup. The parameters taken into consideration include the different fuel and coolant compositions, the form of absorber material, and the various absorber mass and concentrations. It was found that absorption properties of ⁶Li allow reaching the burnup value up to 67 GWd/tHM while reactivity swing is comparable with _eff. The corresponding reactor lifetime is ~10 to 30 yr.