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ph: (865) 576-8401 fax: (865) 576-5728 email: reports@adonis.osti.gov Available to the public from the National Technical Information Service, U.S. Department of Commerce, 5285 Port Royal Rd., Springfield, VA 22161 ph: (800) 553-6847 fax: (703) 605-6900 email: orders@ntis.fedworld.gov online ordering: http://www.ntis.gov/ordering.htmThis document was printed on recycled paper. SummaryThe 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. As part of this effort, the project initiated experimental studies to address issues relating to the chemical reactivity of the degraded/corroded metallic uranium material. The studies generated a limited set of data on chemical reaction rates of the N-Reactor spent fuel in dry-air, moist-air, and moist-inert atmospheres for comparison with published data on unirradiated/irradiated metallic uranium. 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.Evaluations based on laboratory data on samples taken from the corroded N-Reactor spent fuel showed no reactivity enhancement for the degraded metallic uranium in moist atmospheres. The 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 six 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 m 2 for a broken element to 8.1 m 2 for a highly corroded spent nuclear fuel (SNF) element 5744U based on the measured reaction-rate constant for the K-Basin SNF (k SNF ). On the other hand, if the literature-averaged rate constant (k Lit ) is used, the calculated areas are between 0.0002 and 1.1 m 2 .

The 105 K East Basin was originally built to store spent nuclear fuel from the Hanford K East Reactor before processing the fuel in the Plutonium-Uranium Extraction facility. In the 1970s and later years, the basin was used for longer-term storage of N Reactor fuel, which is still the primary content of the basin today. The basin is divided into three bays by two concrete partition walls and contains various pits as well as a discharge-chute area adjacent to the K East Reactor. Each basin contains water nearly 17 feet in depth and has a wetted area of concrete floor and walls of approximately 26,500 ft 2 (i.e., floor 9,900 ft 2 and walls 16,600 ft 2). Currently, sand filter and ion exchange modules provide pathways to remove particulate and contaminants from the water. The K East Basin concrete floor and walls are primarily uncoated. Exceptions are 1) an approximately 1.5-ft band of concrete running around the current basin waterline, which has been wire brushed and coated with epoxy (Huang and Moore 1997) as part of the dose-reduction activities in 1995 (with the water level of the basin subsequently raised approximately 1 foot to its current level) and 2) the Discharge Chute area and portions of the Tech View Pit, which reportedly have been painted (Vargo et al. 1994). Activities to remove spent fuel, sludge, and debris from K East Basin have begun. Once all the radioactive hazards (i.e., fuel, sludge, and debris) are removed from the basin, the basin water will be removed, and the basin will be turned over to a deactivation and decommission contractor. However, the specific approach to achieving this end state is dependent on knowledge of contamination levels in the concrete walls and floor once the water is removed. The Spent Nuclear Fuel Project contracted (a) with the Pacific Northwest National Laboratory (PNNL) to perform nondestructive evaluation of the K East Basin for the purpose of determining concrete contamination levels, including depth of penetration, from selected wall and floor locations below the basin waterline. The definition of the initial requirements and specific approach were controlled through a Data Quality Objectives (DQO) and Sample Analysis Plan (SAP) methodology managed by the Spent Nuclear Fuel Project (Makenas 2002, Baker et al. 2002). This initial approach sought to maximize the useful data from these analyses to make decisions related to final disposition of the K Basins. The K East Basin presents the greatest challenge from the perspective of decontamination for the Spent Nuclear Fuel Project. This is because K East Basin has been in service, storing N reactor fuel, longer than K West Basin (i.e., 1975 versus 1981) and, unlike K West Basin, K East Basin walls and floors were not cleaned and coated with epoxy before entering this type of service. K East Basin also has the greater amount of fuel-bearing sludge in contact with the floor and walls (Baker 1995; Baker 2001). The fact that canisters of fuel in K East Basin do not have lids and often have perforated bottoms (again, unli...

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