Effect of neutron and gamma irradiation on some properties of borate glasses

Abstract

The absorption characteristics, density, and refractive index of some alkali alumino borate glasses containing uranium, have been studied before and after neutron and gamma irradiation, U-free glasses were also studied for comparison. Neutron irradiation showed a negligible effect on the optical absorption of either the U-free or the U-containing glasses. Neutron irradiation prior to gamma irradiation slightly increases the gamma-induced absorption of some borate glasses free of U-atoms; while this may decrease appreciably the gamma-induced absorption for the U-containing glasses. Increasing the pre-neutron dose appeared to restore the original γ-induced absorption intensity produced in the latter glasses when irradiated with gamma rays only. The density and refractive index passed through maxima as the neutron dose was increased. The original values could be restored when such glasses were then gamma irradiated. The irradiated state was found to be a separate state of each glass which depends, largely, upon the neutron dose. The results are discussed on the basis of glass contraction (due to the formation of thermal spikes), and glass dilation (due to atom displacement and bond cracking) for excessive neutron irradiation; and on the basis of the release stresses responsible for the contraction, by gamma irradiation.