Study of BiPbO2NO3 for I-129 Fixation under Reducing Conditions

Abstract

ABSTRACTLeaching of the iodide ion from BiPbO2I (BPI), BPI encapsulated in cement (BPIC) and AgI was studied in a low salinity solution and in a high salinity solution under reducing conditions. Although BPI released a limited amount of iodide ions (less than 1%) into the low salinity solution, it released more than 30% of iodide ions into the high salinity solution within 80 days. AgI released more than 30% of iodide ions into both low and high salinity solutions within 80 days. It was proved that BPI is more stable than AgI in the low salinity solution under reducing conditions. BPIC released a limited number of iodide ions (less than 5%) into both low and high salinity solutions. BPIC showed the best leach resistance in the high salinity solution.BiPbO2NO3 (BPN) was developed to remove iodide ions in a solution and fix them in BPI by the ion exchange reaction. Ion exchange properties under reducing conditions were studied. An anion exchange capacity of 1.0 mEq/g and a distribution coefficient of larger than 0.1 m3/kg were obtained in a solution at a pH of between 9 and 13. The advantages of the process using BPN for removing and immobilizing Iodine-129 were discussed from the standpoint of process simplification.