Interaction of water vapor with UO2(001)

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 00018 m2 for a broken element to 81 m2 for a highly corroded SNF element 5744U The SNF element 0309M that was a clean broken piece was used to calibrate themore » calculation method The result using the SNF reaction rate constant (ie, kSNF) gave a very good (ie, 00018 m2) agreement with the geometrical value of 00015 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)« less

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Reactive Behavior of K-Basin Spent Nuclear Fuel

The water-filled K-Basins in the Hanford 100-Area have been used to store N-Reactor spent nuclear fuel (SNF) since the 1970s. Because some leaks in the basins have been detected and some of the fuel is breached due to handling damage and corrosion, efforts are underway to remove the fuel elements from wet storage. An Integrated Process Strategy (IPS) has been developed to package, dry, transport, and store these metallic uranium fuels in an interim storage facility on the Hanford Site (WHC 1995). Information required to support the development of the drying processes, and the required safety analyses, is being obtained from characterization tests conducted on fuel elements removed from the K-Basins. A series of whole element drying tests (reported in separate documents, see Section 8.0) have been conducted by Pacific Northwest National Laboratory (PNNL) on several intact and damaged fuel elements recovered from both the K-East and K-West Basins. This report documents the results of the first of those tests (Run 1), which was conducted on an N-Reactor inner fuel element (1990) that had been stored underwater in the K-West Basin (see Section 2.0). This fuel element was subjected to a combination of low- and high-temperature vacuum drying treatments that were intended to mimic, wherever possible, the fuel treatment strategies of the IPS. The testing was conducted in the Whole Element Furnace Testing System, described in Section 3.0, located in the Postirradiation Testing Laboratory (PTL, 327 Building). The test conditions and methodology are given in Section 4.0, and the experimental results provided in Section 5.0. These results are further discussed in Section 6.0.

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George S. Klinger

Papers

Drying Results of K-Basin Fuel Element 2660M (Run 7)