The Effect of nitride formation on the oxidation kinetics of Zry-4 fuel cladding under steam-air atmospheres at 1273-1573 K

Negyesi, M.; Amaya, Masaki  

The study deals with the oxidation behavior of fuel cladding under mixed steam-air atmospheres. Oxidation tests of Zry-4 were carried out at temperatures of 1273-1573 K. Post-test weight gain measurement along with metallographic examination were conducted to study separately the kinetics of the region where nitrides formed and the nitride-free region. The weight gain coming from the nitride-free region was estimated employing one-dimensional finite difference oxygen diffusion model and measured thicknesses of the metallic part of the oxidized specimen, the columnar oxide and the oxygen stabilized -Zr(O) as well as the fraction of the columnar oxide at the oxide/metal interface. Consequently, the weight gain related to the nitride formation has been assessed.