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Preferential Radionuclide Release Due to Alpha Decay: Effects on Repository Performance

Published online by Cambridge University Press:  17 March 2011

David A. Pickett
Affiliation:
Center for Nuclear Waste Regulatory Analyses (CNWRA), Southwest Research Institute®, San Antonio, TX 78228-0210, USA
William M. Murphy
Affiliation:
Department of Geological and Environmental Sciences, California State University, Chico, CA 95929-0205, USA
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Abstract

We model preferential release of 237Np, 234U, 230Th, 226Ra, and 210Pb from disposed commercial spent nuclear fuel as a result of alpha recoil damage, using the U.S. Nuclear Regulatory Commission (NRC) Total-system Performance Assessment (TPA) model for the potential repository at Yucca Mountain. Time-dependent augmentation of the ingrown component is simulated by increasing the initial parent inventory; we have used a factor of five increase, based on natural system observations. For 237Np, the magnitude of preferential release is subject to solubility limits. Stochastic TPA runs show a significant effect on modeled dose of preferential 237Np release, but low impact from the other four radionuclides. The mechanism could be ineffective if 237Np is incorporated into secondary phases. While our results are exploratory in nature, this approach to modeling decay-related enhancement of release can be applied in other nuclear waste disposal settings.

Type
Research Article
Copyright
Copyright © Materials Research Society 2004

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