The formation of a stress corrosion crack (SCC) in the canister wall of dry cask storage system (DCSS) has been identified as a potential issue for the long-term storage of spent nuclear fuel. The presence of an SCC in a storage system would represent a through-wall flow path from the canister interior to the environment. Modern, vertical DCSS are of particular interest due to the significant backfill pressurization of the canister up to approximately 800 kPa. This pressure differential offers a relatively high driving potential for blowdown of any particulates that might be present in the canister. In this preliminary study, the carrier gas flow rates and aerosol transmission properties were evaluated for an engineered microchannel with characteristic dimensions similar to those of SCC. The microchannel was formed by mating two gage blocks with a slot orifice measuring 28.9 μm (0.0011 in.) tall by 12.7 mm (0.500 in.) wide by 8.86 mm (0.349 in.) long (flow length). Surrogate aerosols of cerium oxide, CeO2, were seeded and mixed inside a pressurized tank. The aerosol characteristics were measured immediately upstream and downstream of the simulated SCC at elevated and ambient pressures, respectively. These preliminary data sets are intended to demonstrate a new capability to characterize SCC under well-controlled boundary conditions. Separate modeling efforts are also underway that will be validated using these data. The test apparatus and procedures developed in this study are foreseen to be easily modified for the evaluation of more complex SCC-like geometries including laboratory-grown SCC samples.
Year
2020
Abstract