Burst Opening Area of HANA-6 Cladding in Simulated LOCA Conditions

Superior properties of HANA-6 cladding were verified from pool-side examination (PSE) after LTR and LTA programs. Also, to verify the superior properties of HANA-6 cladding up to higher burn-up, an additional LTR program of HANA-6 cladding is being irradiated up to 65 GWD/MTU. The post-irradiated examination (PIE) programs of HANA-6 cladding irradiated in commercial reactors are planned. Recently, the fuel fragmentation, relocation, and dispersal (FFRD) during LOCA situation has been emerged as one of the critical obstacles for licensed burn-up extension of nuclear fuel. Based on recent research results, FFRD is affected by fuel average burn-up as well as cladding burst behaviors such as burst strain, depressurization of internal rod pressure when cladding is burst, and burst opening area. Among these systematic parameters, the burst opening area could determine the critical fragmentation size for dispersal. Furthermore, it is possible that the burst opening area could be affected by test conditions such as heating rate, internal rod pressure, and cladding properties. In this regards, the burst opening behaviors of HANA-6 cladding is very important to evaluate FFRD. KEPCO NF has performed a lot of burst tests of HANA-6 cladding in simulated LOCA conditions to burst model development. In this study, the burst opening areas of HANA-6 with various test conditions were measured from tested specimens and well characterized. A lot of burst tests of HANA-6 tubes were performed at various heating rates and engineering hoop stresses.