Secondary creep behavior of Zr-4 claddings under LOCA conditions

International audienceThe thermo-mechanical behavior of Zircaloy-4 fuel rods under Loss-Of-Coolant Accident (LOCA) conditions is investigated. A custom experimental setup is dedicated to the high-temperature creep ballooning study of 90mm long cladding samples. Creep tests were performed under an inert environment (argon), for temperatures from 750 to 850 °C and internal pressures ranging from 1 to 5MPa. During its operating life, Zr-4 cladding is submitted to oxidation and hydriding. These parameters strongly influence the creep behavior of Zirconium alloys at high temperatures. A first campaign on as-received Zr-4 was performed. Creep-rates are computed using 2-Dimensional Digital Image Correlation (2D-DIC) and are correlated to local temperatures measured using Near Infra-Red thermography. As-received Zr-4 behavior laws are determined using Finite Element Model Updating (FEMU). Norton exponents and activation energies are determined for thermal-mechanical conditions of the performed tests. The stress and temperature effects on the steady-state creep parameters are highlighted in this study