Effect of alkali halide additives on the gamma radiolysis of thorium nitrate

Abstract

Gamma radiolytic decomposition of thorium nitrate and its binary mixtures with potassium halides has been studied over a wide absorbed dose range (upto 600 kGy) and at different compositions. G(NO) values decrease on the addition of halides, except for several fold enhancement at 75% composition in low dose region. A part of the energy is taken up by the additive and later transferred to the nitrate thus affecting its decomposition. Reflectance spectra of irradiated binary mixtures show characteristic bands corresponding to the formation of X<img src='http://www.niscair.res.in/jinfo/two.gif' border=0> and colour centres (V and F). Thermoluminescence (TL) studies of pure halides and its binary mixtures with thorium nitrate suggest the formation of radical species affecting the decomposition. EPR measurements on <em>γ</em>-irradiated thorium nitrate indicate the presence of NO₂, O<img src='/image/spc_char/3_bar.gif' border=0> and O<img src='http://www.niscair.res.in/jinfo/two.gif' border=0>. A plausible mechanism has been proposed.