Reactive Behavior of K-Basin Spent Nuclear Fuel

The Hanford Spent Nuclear Fuel Project focuses its efforts on determining how to safely move the degraded N-Reactor spent fuel from water-stored basins to a dry storage facility. Based on the laboratory data, the project chose to use a conservative enhancement factor in analyzing the oxidation behavior of the spent metallic fuel. However, there is a need for the project to increase the fuel throughput for the drying treatment process by implementing certain design optimization steps. The study discussed in this paper re-evaluated the previous laboratory data in conjunction with the cold vacuum drying (CVD) process experience and determined whether the built-in level of conservatism could accommodate the potential changes in the process without compromising public and worker safety. An established oxidation reaction-rate constant was used to accurately determine the reactive surface areas of corroded N-Reactor fuel elements. The surface areas calculated for 6 different N-Reactor elements that were stored in the K-West Basin and shipped to Pacific Northwest National Laboratory for drying studies ranges from as low as 0.0018 m2 for a broken element to 8.1 m2 for a highly corroded SNF element 5744U. The SNF element 0309M that was a clean broken piece was used to calibrate the calculation method. The result using the SNF reaction rate constant (i.e., kSNF) gave a very good (i.e., 0.0018 m2) agreement with the geometrical value of 0.0015 m2. Having established that the hydrogen generation can be used to determine the exposed surface area of these irregular corroded SNF elements, the calculations was extended to provide a good estimate of the exposed uranium surface area of SNF elements loaded into the multi-canister overpacks (MCOs)