Benchmark calculation and application of SCALE4.3 CSAS6 module

Calculation biases of SCALE4.3 CSAS6 module for PWR spent fuel, metallized spent fuel and solution of nuclear materials have been determined on the basis of the benchmark to be 0.01100, 0.02650 and 0.00997, respectively. With the aid of the code system, burnup credit criticality analysis has been performed for infinite arrays of square and hexagonal canisters containing metallized spent fuel rods with changing canister wall thickness, canister surface-to-surface distance and water concentration. The results show that canister arrays, above 9 mm thickness of canister wall, are believed to be below the subcritical limit regardless of external conditions. Besides, the minimum burnup required for safe storage under the infinite array of spent fuel assemblies is estimated to be 5600 MWD/MTU in the case of 5.0 wt% initial enrichment