Separation of 137 Cs from Acidic Nuclear Waste Simulant via an Engineered Inorganic Ion Exchanger
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Separation of 137Cs from Acidic Nuclear Waste Simulant via an Engineered Inorganic Ion Exchanger T.J. Tranter1*, T.A. Vereshchagina2, A.G. Anshits2, E. Fomenko2, A.S. Aloy3, N.V. Sapozhnikova3 1
Idaho National Engineering and Environmental Laboratory, P.O. Box 1625, Idaho Falls, ID USA, 83415 2 Institute of Chemistry and Chemical Technologies, 42 K. Marx St., Krasnoyarsk, Russia, 660049 3 V.G. Khlopin Radium Institute, 2-nd Murinskiy Ave., St. Petersburg, Russia, 194021 ABSTRACT An engineered ion exchange material has been prepared for the specific purpose of removing radioactive cesium from acidic waste. Separating the fission product 137Cs from the bulk of the nuclear waste stream is often advantageous because, after typical cooling times, this isotope is usually the primary source of gamma radiation dose. The engineered ion exchanger was prepared using ammonium molybdophosphate impregnated into hollow glass crystalline microspheres. The microspheres or cenospheres, are refractory compounds of silica and alumina that are derived from the fly ash produced in coal combustion. This paper describes equilibrium experiments that were conducted with the engineered ion exchanger and a simulated acidic waste solution. These tests indicate that the new material has a high capacity and selectivity for cesium in these matrices. INTRODUCTION Approximately 3.4 million liters (900,000 gallons) of acidic aqueous nuclear waste are currently stored at the Idaho National Engineering and Environmental Laboratory (INEEL) in a collection of underground tanks known as the tank farm. The INEEL tank farm originally consisted of eleven underground, stainless steel tanks, of approximately 300,000-gallon capacity. In an on-going effort to decommission and close the tank farm, the remaining liquid waste has recently been consolidated into 4 tanks. This liquid waste is the result of various decontamination activities associated with the reprocessing of nuclear fuel during the 1950’s to the early 1990’s. Consequently, the waste has a relatively high concentration of fission products, nitric acid, and non-radioactive metals, which makes it a very complex matrix from a waste treatment standpoint. Although the composition of the waste in the remaining active tanks varies slightly, it is likely that some type of blending will take place prior to the initiation of any type of waste treatment process. Multiple technologies for treating and removing the liquid waste remaining in several tanks are being investigated. One of these technologies is the cesium ion exchange (CsIX)/Stabilization option which would convert the liquid waste into a contact__________________________________________________________________________ Corresponding author: email [email protected]
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handled solidified waste that would meet waste acceptance criteria for disposal at the Waste Isolation Pilot Plant (WIPP). Under this option, the liquid waste would be filtered, passed through ion exchange columns to remove cesium, and then stabilized in a solid for
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