Irradiation tests of mixed-oxide fuel prepared with weapons-derived plutonium

Mixed-oxide test capsules prepared with weapons-derived plutonium have been irradiated to a burnup of 50 GWd/MT. The mixed-oxide fuel was fabricated at Los Alamos National Laboratory by a master-mix process and has been irradiated in the advanced test reactor at the Idaho National Laboratory. Previous withdrawals of the same fuel have occurred at 9, 21, 30, and 40 GWd/MT. Oak Ridge National Laboratory manages this test series for the Department of Energy’s Fissile Materials Disposition Program. This paper describes the preparation of the mixed-oxide fuel, the equipment design, and the irradiation history of the test capsules, and discusses the significance of the more important observations of the post-irradiation examinations. Code predictions (FRAPCON-3 and TRANSURANUS) are presented and compared with available post-irradiation examination data for the highest and lowest powered mixed-oxide capsules. Fuel performance has been excellent and consistent with code predictions and with existing US and European experience.