Application of Acid Digestion to Reprocessing Wastes and Chemicals

摘要

A wide variety of waste materials or chemicals potentially associated with fuel reprocessing operations were treated using acid digestion. The materials were divided into three categories: organic solvents, cleaning solutions and decontamination reagents, and miscellaneous process chemicals. In addition, separate studies were performed to determine the behavior of iodine, ruthenium, and soluble neutron poisons in the acid digester. Studies were also performed to determine the fate of plutonium, americium, and uranium in the acid digestion system. All chemicals examined were decomposed, with the exception of carbon tetrachloride (CCl sub 4 ) and normal paraffin hydrocarbon (NPH) which distilled from the digester. As expected, ruthenium and iodine volatilized during acid digestion. Dry, solid potassium permanganate reacted very violently in the acid digester, probably due to formation of manganese heptoxide which is explosive at high temperatures. Potassium permanganate should not be added to the digester in large quantities in dry solid state. Plutonium and americium form semi-soluble sulfates during acid digestion and will remain with the process residue. Both are readily leachable in dilute nitric acid. Solubilities of plutonium and americium were estimated to be 0.1 g/l and 0.0015 g/l, respectively. Uranium, on the other hand, is soluble in acid digestion solutions to greater than 100 g/l. Limited laboratory data indicate the acid digestion process is capable of processing combustible solid wastes from reprocessing plants. However, limitations could be imposed by the volatilization of iodine and ruthenium from the digester. Accordingly, the level of radioactivity in effluents will require further evaluation. (ERA citation 07:059289)