567 / 2019-03-20 17:52:28

Hydrogen Release Behavior of Lithium Hydride under High-energy X Ray Irradiation

Nuclear reactor shield,Irradiation effect,Hydrogen evolution

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The hydrogen evolution of lithium hydrides (LiH) under gamma ray irradiation has attracted much attention because of its potential application in a space nuclear reactor shield. However, LiOH impurities, which usually exist on the surface of LiH, will react with LiH (LiOH+LiH→Li2O+H2) during irradiation, and the produced hydrogen is hardly distinguished from the one generated by radiolysis (LiH→Li +H2). Stable isotope tracing is an effective way to identify the origin of hydrogen, which provides more evidence for illustrating the hydrogen release behavior of irradiated lithium hydrides.
In this paper, LiD was introduced to investigate the deuterium generation during 9MeV X ray irradiation, and the effects of energy, dose and dose rate on deuterium releasing were studied. A lot of D2 and a trifle of HD are generated during irradiation, suggesting that deuterium mainly originates from radiolysis, rather than from radiation-induced chemical reaction. The amount of D2 increases with the increase of irradiation dose rate, and linearly increases and decreases with the increase of energy and dose, respectively. Besides, as the dose and dose rate increase, lattice damage firstly aggravates, and when the dose reaches over 7000Gry, annealing effects then become prominent and lattice distortion is recovered to some extent. Large quantity of parallel cracks observed in irradiated LiD samples imply that hydrogen may mainly release from their cleavage facets. Surface damage gradually deepens with increasing doses, which manifests the preferential paths forD2 escape.