Review of Empirical Thermodynamic Data for Uranyl Silicate Minerals andExperimental Plan

摘要

Experimental and natural analog data indicate that uranyl silicate minerals arelikely to form as oxidation products of spent nuclear fuel in a high-level radioactive waste respository at Yucca Mountain, Nevada. A basis for thermodynamic modeling of uranium chemistry is provided by a recently compiled database, which contains no data for uranyl silicate minerals. Two recent publications purporting to have determined equilibrium solubilities for uranyl silicates were critically reviewed. An experimental plan has been developed to determine thermodynamic properties of uranyl silicate minerals through original experimentation and data interpretation. Plans are also described for experiments that are designed to determine the importance of coprecipitation reactions as mechanisms for limiting the release and transport of actinides such as plutonium and neptunium.