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Oxidation of Fuel Rod under Dry Storage Condition.

1995; Taylor & Francis; Volume: 32; Issue: 4 Linguagem: Inglês

10.3327/jnst.32.321

1881-1248

Jinichi Nakamura, Takayshi OTOMO, Teruco KIKUCHI, Satoru Kawasaki,

Mechanical Failure Analysis and Simulation

Oxidation tests of irradiated and un-irradiated rod with an artificial defect hole were Per-formed 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 in-crease due to volume expansion caused by the generation of U3O8 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 UO2 pellet occurred preferentially at the grain boundary and that the crystal structure corresponding to U4O9 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 UO2 matrix. 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.