Damage detection of spent nuclear fuel canisters using frequency response functions

Abstract

This paper investigates the use of the frequency response functions (FRFs) of a sealed spent-nuclear fuel canister when it is subjected to an external vibration to detect abnormalities to its contents. The variation in the FRFs as an indication of probable damage is introduced and examined. Both finite element (FE) simulations and experimental analyses of a mock-up fully loaded canister basket system were performed. An efficient methodology that employs model reduction techniques to perform FRF calculations for high-fidelity finite element models (FEMs) was used. The experimental work was conducted using a modal shaker to excite the canister at the bottom plate and to collect acceleration measurements at various locations. The location of hypothetical damage cases (missing fuel assemblies) was accurately determined in both computational and experimental models employing the framework that is introduced in this study. Furthermore, additional possible damage scenarios are introduced and analyzed with the FEM. Although the FEM could identify the location of abnormalities for most of the cases considered here, when the damage was local and minor, the differences in the FRFs were minute, which rendered the damage detection challenging. Finally, the study concludes that the use of dynamic vibration measurements on the outside of a canister can provide valuable information to detect physical abnormalities in a sealed spent nuclear fuel (SNF) package.