Irradiation testing of intermediate and high-density U-Mo alloy dispersion fuels to high burn-up

Two irradiation test vehicles have been designed, fabricated, and inserted into the Advanced Test Reactor in Idaho. Irradiation of these experiments began in August 2000. These irradiation tests were designed to obtain high-burnup irradiation performance data on a series of intermediate and high-density U-Mo alloy dispersion fuels at nominal research reactor thermal conditions. The two irradiation experiments each contain 32 miniature fuel plates. The test matrix of fuel compositions include U-10Mo, U-7Mo and U-6Mo fuel plates fabricated at densities of both 6 and 8 g-U/cm3, and U-6Mo-1.7Os and U3Si2 (included as a standard) fuel plates fabricated at 6 g-U/cm3. Fabrication techniques used to produce the fuel powders included grinding and atomization. The matrix phase of each fuel plate is aluminum, with the exception of two fuel plates which are aluminum-clad U-10Mo foils (i.e., no matrix phase). The peak fuel temperatures are approximately 180 deg. C at beginning-of-life. These experiments, designated RERTR-4 and -5, will be discharged at peak fuel burnups of approximately 50 and 80 at.% U235. Of primary interest are the collection of quantitative data on the extent of interaction between fuel and matrix phases and the fission gas retention/swelling characteristics of these fuels up to very high burnup. This paper presents the design of the irradiation tests and the irradiation conditions. (author)