Irradiation Test of Annular UO2 Pellet in the HANARO

In-reactor behavior of the annular UO2 fuel could be different from the conventional solid UO2 fuel because it is expected to be operated at low temperature and the geometrical shape of the two kinds of fuel rods is not identical. Since the annular pellet temperature of the annular fuel rod is lower than the solid fuel by several hundred degrees, densification and swelling . Although they are generally known as athermal phenomena could be affected by low temperature. In contract with the solid fuel having only one gap, annular fuel has both inner and outer radial gaps which can accommodate the change in pellet volume. A number of cracks and crack pattern created in annular pellet could be different from those in the conventional solid pellet because temperature profile and hence thermal stress distribution in the two pellets would not be the same. Therefore, in order to investigate the in-reactor behavior of the annular UO2 pellet, the irradiation test was carried out in the HANARO and post irradiation test is being carried out in the KAERI's PIE facility