Trapping and Desorption of Hydrogen Isotopes under Irradiation of Zirconium Alloy E110 with Ions of Deuterium Plasma.

The paper investigates the trapping and desorption of hydrogen isotopes under irradiation of zirconium alloy E110 with ions of deuterium plasma. It is established that, under the irradiation, hydrogen exchange between the alloy and the gaseous ambient occurs: part of deuterium from the irradiation flux is trapped by the alloy, and at the same time, hydrogen initially contained in the alloy is partially desorbed. In general, hydrogen exchange results in an increase in the content of hydrogen isotopes in the sample. Addition of 30 at % oxygen to the plasma-forming gas, as well as increasing the sample temperature from T = 450 K to T = 600 K, slows down deuterium trapping and accelerates hydrogen desorption, leading to a decrease in the content of hydrogen isotopes in the sample. Increasing the dose of irradiation of E110 alloy with deuterium plasma ions intensifies both deuterium trapping and hydrogen desorption. On the basis of the experimental results, the mechanism of hydrogen exchange between zirconium alloy and gaseous ambient under the ion irradiation is proposed. The process includes three stages: reactions on the oxidized surface of zirconium alloy (hydroxylation of surface oxide and formation of water molecules); reactions on the metal–oxide boundary; and transport of hydrogen isotopes through the surface oxide layer in both directions. Surface reactions initiated by irradiation trigger the hydrogen exchange process. [ABSTRACT FROM AUTHOR]