Mechanical behavior of as-fabricated Zircaloy-4 claddings under the simulated thermo-mechanical post-DNB conditions of a Reactivity Initiated Accident (RIA)

International audienceThe present work aims at characterizing the thermal-mechanical behavior of as-fabricated Stress Relieved Annealed (SRA) Zircaloy-4 claddings under simulated loading conditions of a Reactivity Initiated Accident (RIA), just after Departure from Nucleate Boiling (DNB). An experimental device was setup in order to simulate post-DNB conditions on fuel rods samples. Ballooning creep tests were performed in inert environment (argon) at internal pressure ranging from 1 to 50 bar. A thermal loading was applied by induction heating. First, the sample was heated at 1000°C/s. The temperature was then stabilized at the test set point until the burst of the specimen. Typical investigated temperatures ranged from 800°C to 1100°C in the two-phase domain. Thermal and 3D-kinematics fields were recorded during the whole experiment using high-speed cameras. The present paper shows the results of two tests highlighting a strong impact of the thermal transient