Mockup Testing For Spent Fuel Storage Canister Accelerating Vacuum Drying

摘要

For nuclear power plants, spent fuel assemblies are placed into spent fuel storage canisters for storage in Independent Spent Fuel Storage Installations. Prior to storage, these canisters are drained, purged, and vacuum dried to remove residual water. Some low decay heat load spent fuel storage canisters have required excessively long vacuum drying times. A primary reason is water trapped in the bottom of guide tube channels. Mockup tests simulating an actual spent fuel canister configuration have been performed to investigate the effect of various methods to accelerate the vacuum drying. For spent fuel assembly guide tubes without bottom drainage holes, problematic water can become trapped during storage canister draindown. For a particular fuel assembly design and storage canister design, as much as 29 liters of water can be trapped inside the spent fuel assembly guide tubes below drainage holes in the side of the guide tubes. The vacuum drying of the trapped water can be restricted by icing and by the presence of the control rods in the guide tubes or flow mixers on top of the guide tubes.