Dependence of spent fuel oxidation on burnup

Prior to US Department of Energy (DOE) acceptance starting in 1998 of spent fuel from utilities for ultimate disposal, interim dry storage of spent light water reactor (LWR) fuel is being considered by US utilities as an option for spent fuel management. The selection of a gas atmosphere and the appropriate storage criteria are key considerations for licensing dry storage installations. A technical basis for storing spent LWR fuel in inert gases in the US has been developed. However, the technical basis for storing spent fuel in air and the fuel temperature below which inert gas monitoring requirements can be relaxed have not been clearly identified. Experiments to determine the oxidation behavior of US spent LWR fuel have been sponsored by DOE, the US Nuclear Regulatory Commission, the Electric Power Research Institute, and the Tennessee Valley Authority. These studies have revealed that induction times for powder formation tend to increase for spent fuel compared with the behavior of nonirradiated UO/sub 2/. Oxidation tests with spent LWR fuel with burnup levels ranging from 7500 to 32,000 MWd/MTU are being conducted at Pacific Northwest Laboratory under the Commercial Spent Fuel Management Program. These tests are designed to establish criteria for storage ofmore » spent LWR fuel in oxidizing atmospheres and to determine the threshold temperatures below which inert gas monitors can be deactivated.« less