Finite element analysis of stresses and deformations occurring in the spent nuclear fuel (SNF) disposal canister deposited in a deep geological repository

Abstract

Numerical computer experimental methodologies are investigated for the weight reduction of a spent nuclear fuel (SNF) disposal canister designed to be deposited in a Korean deep geological repository from a pressurized water reactor (PWR). Finite element analyses of stresses and deformations occurring inside the cylindrical canister under the deposited conditions are performed to assess its structural strength at various rotation angles (φ) of the SNF basket. Specifically, the cross sections of four square tube shaped SNF baskets (assemblies) contained in the canister are rotated. Using a conventional structural analysis and a Kriging method, an optimal rotation angle is determined in relation to canister diameter and weight. Both sets of results are in agreement. It was also determined that the computed deformation changes slightly in relation to variances in rotation angle, while the stress incurred inside the cast iron insert of the canister noticeably changes reaching its highest value at φ=45° while still maintaining safe structural integrity. It is concluded that the diameter of the canister can be reduced from its original design value (102cm) to 95.8463cm resulting in a ∼16.0% reduction in canister weight for an optimal rotation angle of 45°.