Behavior of Accident tolerant fuel cladding under simulated Loss-of-coolant Accident Condition

Accident tolerant fuel (ATF) cladding has been widely studied by several research groups after Fukushima nuclear reactor accident. Oxidation barrier layer coated Zr fuel cladding is one of the most promising candidate concepts owing to its easy process and lower cost for manufacturing and possibility of developing with short term study compared to other ATF concepts. We have successfully fabricated CrAl alloy coated ATF tube samples by using existing Zr fuel cladding for light water reactors (LWR). In this study, integral loss-of-coolant accident (LOCA) tests simulating real conditions of fuel claddings during accident were conducted using ATF cladding samples for a clear understanding of their behavior under accident conditions. Ballooning and rupture behavior and of ATF cladding during the LOCA scenarios were studied systematically. To improve the reliability and safety of existing Zr alloy fuel cladding under LWR accident conditions, a high temperature oxidation resistant layer was coated onto the surface of Zr alloy samples using various coating techniques. The rupture temperature of the coated tube was higher than that of the uncoated cladding. The circumferential strain and the size of the rupture opening at the ballooned area were smaller when the Zr tube was coated.