Behavior of Iodine-131 in Dissolution of Irradiated Uranium Dioxide

A hundred milligram of UO2 was irradiated In JRR-4 (burn up 0.017%) and dissolved In boiling 3 M-HNO3 (20 ml) to study the behavior of fission-product iodine (131I, − 1 ng) During the dissolution, 80–90% of the iodine volatilized together with 133Xe. Zeolite 13X (–4g) trapped completely the iodine in the dissolver off-gas Blowing a NO2 flow through the solution was effective for expulsion of the remaining iodine and finally 90–95% of the initial iodine was removed from the solution with the aid of addition of KIO3. The Iodine species in the solution includes I2, I−, IO3 − (IO4 −), organic iodides and other unknown species The expulsion operations caused the unknown species to increase In relative abundance. This tendency was also noticed for iodine of higher concentration in 3 M-HNO3.