Chemical states of35S in solutions of thermal neutron irradiated chlorides

The chemical states of 35S in solutions of thermal neutron irradiated (TNI) chloride samples have been investigated using (a) chemical precipitation techniques after sample dissolution in the presence or absence of inactive carriers in the forms of S2-, SO3 2-, SO4 2- and S2O3 −2, and (b) anion exchange separation. The second method has been used to study variations in the composition of TNI chloride solutions as a function of the time interval between sample dissolution and addition of the solution to the ion exchange column. The results point towards the following conclusions: (i) dissolution of TNI chloride in water or 0.3 M NaOH in the absence of any inactive sulfur-anion carrier yields primarily 35SO3 2- and not 35SO4 2- and 35S2- as was thought earlier; (ii) about 20% of the 35S in solution is present initially as elemental sulfur; (iii) the composition of the solution varies markedly with time; (iv) in the presence of carrier sulfur anions at the time of dissolution different 35S-species are formed; and (v) chemical precipitation techniques do not give a true indication of the species present in solution.