Failure correlation for zircaloy-2 fuel cladding under high temperature transient conditions

Thermal transient and isothermal tests on unirradiated Zircaloy-2 fuel cladding were conducted by determining short-term failure behaviors depending on temperature transients under constant differential internal pressure conditions. Failure data for constant heating rate transient tests were converted to Larson-Miller Parameter (LMP) values on the basis of the life-fraction rule. It was found that failure data for both the transient and isothermal tests were reduced to a single curve described by a correlation between LMP and initial hoop stress. Also, the failure strength during isothermal holdings after thermal transients was successfully evaluated by summing up life-fractions corresponding to each temperature process, using the LMP correlation. The LMP correlation approach could be used to predict the transient mechanical response of fuel cladding under high temperature conditions.