Experimental Observation on Burst Behaviors of HANA-6 Cladding in LOCA Conditions

HANA (High performance alloy for nuclear application) alloy was developed in order to meet the global demand for an extension of the fuel discharge burn-up to more than 70 GWd/MtU. Superior properties of HANA-6 cladding were verified from pool-side examination (PSE) after LTR and LTA programs. Also, post-irradiated examination (PIE) of HANA-6 cladding irradiated in commercial reactors is being conducted. Besides, the performance of HANA-6 cladding in loss of coolant accident (LOCA) conditions should be evaluated. Since it is known that cladding burst behaviors could induce the coolant blockage during LOCA, the understanding on burst behaviors of HANA-6 cladding and the related burst model are necessary to analyze the nuclear fuel behaviors during LOCA. In this study, many of burst tests of HANA-6 cladding in simulated LOCA conditions have been performed. The experimental observation from the burst tests were summarized. Much of burst tests of HANA-6 tube were performed at various heating rates and engineering hoop stress. The experimental observation were summarized as bellows. 1. From the hoop stress vs. burst temperatures curves, the burst temperatures were not depended on the heating rates. 2. From the burst temperatures and burst strain curve, the lowest burst strain region were observed at the temperature range from 800℃ to 900℃. 3. In the range of lower burst temperature below 900℃, the burst strain was increased with decreasing heating rate. On the other hand, above 900℃, the burst strain was not affected by heating rates.