Irradiation test of the high burn-up large grain UO2 pellets in HANARO reactor

The large grain UO2 pellet developed for the high burn-up PWR fuel is under irradiation in the HANARO since July of 2002. The large grain UO2 pellets will be irradiated up to the burn-up higher than 70 MWD/kgU. To irradiated the UO2 pellets up to the burn-up 70 MWD/kgU, it takes about 60 months and therefor to ensure the integrity of the irradiation capsule, the capsule will be replaced by the new capsule after 30 months. The burn-up of the fuel rods was 19.5 MWD/kgU for the upper three fuel rods and 21.8 MWD/kgU for the lower three fuel rods, as of the end of 2003 by which the effective irradiation time is 320.6 day at 24MW power HANARO. To confirm the integrity of in-pile capsule, the visual examination of the capsule has been three times, a showing excellent performance of the capsule with no sign of the wear