Oxidation and embrittlement behaviors of Zry-4 cladding in steam-air mixtures at high temperatures

Negyesi, M.

The presentation deals with oxidation behavior of Zry-4 fuel cladding during severe accidents of LWR. Zry-4 fuel cladding was exposed in steam-air mixtures at temperatures of 1273-1473 K. Specimen weight gain was measured, metallographic observations were carried out, hydrogen uptake was determined and ring compression tests were conducted. It was found out that the oxidation behavior of Zry-4 may be affected significantly by the experimental setting. Higher air fraction in steam accelerated the oxidation kinetics substantially. The kinetics of the oxide and -Zr(O) layers have been also assessed. Substantial hydrogen pick-ups were measured, strongly depending on the air fraction. As a consequence, the mechanical properties deteriorated significantly.