Study offers new insights into the storage of nuclear waste

by William G. Gilroy

Researchers from the University of Notre Dame offer new insights into conditions that might develop at radioactive material repositories, such as the one planned for the Yucca Mountains in Nevada, in a study published this week in the journal Science.p. Peter C. Burns, Massman Professor of Civil Engineering and Geological Sciences, and Karrie-Ann Hughes, a doctoral student in the department, studied the stability of uranyl minerals containing peroxide. Two minerals – studtite and metastudite – are the only known peroxide-bearing minerals.p. Numerous laboratory studies have been designed to stimulate the alteration of spent nuclear fuel under conditions similar to those expected at the Yucca Mountain radioactive material depository, which is scheduled to open in 2010. However, these studies have concentrated on uranyl oxides and uranyl silicates as the dominant products involved in the alteration of spent nuclear fuels, rather than on uranyl peroxides such as studtite and metastudtite.p. Burns and Hughes have found that studtite and metastudtite may be important alteration phases of nuclear waste under long-term storage, possibly at the expense of the more commonly anticipated uranyl oxides and silicates. Their research indicates that natural radioactivity in a uranium deposit or the radioactivity of nuclear waste can create sufficient water for studtite formation.p. Studtite also has been found on the surface of spent nuclear fuel contained in K East Basins of the Hanford, Wash., nuclear site and on nuclear material after the Chernobyl Nuclear Plant accident.p. Burns and Hughes suggest that uranyl peroxides must be considered in the assessing the impact of uranyl materials on the release of radioactivity from nuclear waste in a depository.p. Katheryn B. Helean and Alexandra Navrotsky of the University of California, Davis, also participated in the study.

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