Oxidation of Fuel Rod under Dry Storage Condition
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Oxidation tests of irradiated and un-irradiated rod with an artificial defect hole were performed in air and air-argon mixed gas between 473K and 513K to study the oxidation behavior of damaged fuel rod during dry storage. Rods oxidized in air showed diameter increase due to volume expansion caused by the generation of U<SUB>3</SUB>O<SUB>8</SUB> and the cladding of irradiated rod was broken after the diameter increase had reached about 2%. X-ray diffraction and metallography showed that the oxidation of irradiated UO<SUB>2</SUB> pellet occurred preferentially at the grain boundary and that the crystal structure corresponding to U<SUB>4</SUB>O<SUB>9</SUB> remained stable even after about 11, 200h oxidation in air at 473K. It was suggested that the difference of the oxidation between irradiated and un-irradiated rods was due to FP gas bubble accumulation at grain boundary and FP accumulation in UO<SUB>2</SUB> matrix.<BR>The oxidation rate of fuel rod in air-argon mixed gas was lower than that in air irrespective of irradiation. The irradiated rod in low oxygen partial pressure showed very little deformation.
- Journal of Nuclear Science and Technology
Journal of Nuclear Science and Technology 32(4), 321-332, 1995-04-25
Atomic Energy Society of Japan