Chemistry of 128I in alkaline aqueous solutions of sodium iodate activated by thermal neutrons

Abstract

The retention of ¹²⁸I in crystalline sodium iodate at room temperature irradiation is found to be 67.8%, which is quite different from the value of 56.0% observed on irradiation at liquid-nitrogen temperature. Radiative-neutron capture in frozen alkaline aqueous solution of the target irradiated at liquid-nitrogen temperature yields a retention value of 35.1% compared with a value of 23.9% at room temperature for the same solution. Dilution of alkaline aqueous solution with additives (i.e. KCl, NaCl, KOAc and NaOAc) prior to neutron irradiation in varying amounts results in an increase of retention in general; also the yield of radioperiodate increases almost reaching a plateau at a molar ratio of additive to target of ca. 1:1. The results are explained in the light of a model which invokes the oxidizing–reducing nature of the intermediates produced during neutron irradiation.