Features of Hydrogen Trapping under Irradiation of Zirconium Alloys with Electrons in Various Gaseous Ambient.

The features of hydrogen trapping under the irradiation of zirconium alloys E110 and E635 with an electron beam (400 eV, 0.8 mA/cm2) in various gaseous ambient containing oxygen and hydrogen (Ar + O2 + H2; Ar + H2O) are studied. The effect of surface temperature on the hydrogenation of zirconium alloys under electron irradiation is studied. It is shown that neither exposure nor electron irradiation in a gaseous ambient containing a mixture of H2 and O2 at 700 K for 20 h leads to a change in the hydrogen level in the E110 alloy, while hydrogen partially escapes from the E635 alloy during the experiment. The amount of hydrogen in zirconium alloys after exposure in a gaseous ambient containing H2O in a similar temperature–time regime also changes insignificantly; however, if the alloys are irradiated with electrons under these conditions, then they contain 1.5–2 times more hydrogen. When temperature of the samples is raised to 900 K, electron irradiation in the presence of water vapor, on the contrary, reduces the trapping of hydrogen in the E110 and E635 alloys, compared with exposure in the same gaseous ambient without irradiation. It is concluded that electron irradiation affects the balance of surface reactions of formation of hydroxyl groups from adsorbed water molecules and reverse reactions of formation of water molecules from surface hydroxyls. The direction of shifting the balance of these reactions depends on the surface temperature. [ABSTRACT FROM AUTHOR]