Hydrogen permeation rate of coating zirconium hydride moderator—A prediction model

Abstract

A prediction model for hydrogen loss rate (HLR) of coating zirconium hydride at 873 K based on Wagner's model was established using gas chromatograph. A continuous and dense coating of zirconium hydride with bilayer structure was prepared by phosphation-oxidation method. The oxidation weight gain of coating zirconium hydride specimens at 873 K in a mixture atmosphere of CO2 and He was investigated. The oxidation weight gain law was obtained by fitting Wagner's model, and the release equation of CO were further deduced. The concentration of H2 and CO in the gas phase was measured by gas chromatograph in the closed system under the same conditions. The optimized HLR of coating zirconium hydride was obtained by deducting the amount of CO generated by the reaction of zirconium and CO2 using the release equation of CO. Fitted by Wagner's model, the dependence between optimized HLR and reaction time was obtained, and the loss amount of hydrogen at any moment can be calculated by extrapolated and integrated, thus a prediction model was established. Based on the model, the HLR of coating zirconium hydride is 0.97% in 1 year. Highlights A prediction model for hydrogen loss rate of coating ZrHx at 873 K was established using gas chromatograph. A continuous and dense coating of ZrHx with bilayer structure was prepared by phosphation-oxidation method. Fitted by Wagner's model, the equation of hydrogen permeability rate was obtained. The prediction model was further optimized by deducting the amount of CO produced by the reaction of Zr in CO2.