An evaluation of rate constants for radiation induced decomposition of alkali metal nitrates

Abstract

Radiation induced decomposition of solid alkali metal nitrates at room temperature has been studied up to an absorbed dose of 300 kGy. [NO ⁻₂ ] increases with absorbed dose. From the kinetic scheme$NO_3^ - \xrightarrow{{{}^k1}}NO_2^ - + 0; O + NO_2^ - \xrightarrow{{{}^k2}}NO_3^ - ;$ and$O + NO_3^ - \xrightarrow{{{}^k3}}NO_2^ - + O_2$, rate constants have been evaluated for the overall radiolytic decomposition of alkali metal nitrates. This kinetic scheme is applicable in the low dose range. At higher doses, however, the radiation induced reaction, NO ⁻₂ +1/2 O₂⇝NO ⁻₃ may also contribute. The overall rate constants are 0.13×10⁻⁶ (LiNO₃), 1.05×10⁻⁶ (NaNO₃), 10.10×10⁻⁶ (KNO₃), 9.50×10⁻⁶ (RbNO₃) and 25.50×10⁻⁶ (CsNO₃) kGy⁻¹.