Ring compression ductility of high-burnup fuel cladding after exposure to simulated LOCA conditions

Nagase, Fumihisa ; Chuto, Toshinori; Fuketa, Toyoshi

Ring compression tests were conducted with specimens sampled from high-burnup fuel cladding segments which had been ruptured, oxidized at 1405 - 1484 K and quenched in the LOCA-simulated experiments. The plastic strain to failure and the maximum load decrease with increasing oxidation and hydrogen. Embrittlement of the cladding is seen when the hydrogen concentration is above 300 - 400 ppm. Although all the examined fuel cladding segments did not facture in the LOCA-simulated experiments, most the specimens failed without plastic deformation in the ring compression tests. The obvious discrepancy between the fracture/no-fracture criterion and the embrittlement criterion is likely caused by difference in the loading conditions in the two tests.