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Ion Exchange in High-Level Nuclear Waste Encapsulation: Atomistic Modeling of Equilibrium Coefficients and Isotherms

Published online by Cambridge University Press:  10 February 2011

T. Kletskova
Affiliation:
Department of Nuclear Engineering, Massachusetts Institute of Technology, 77 Massachusetts Av., Cambridge, MA 02139
K. Czerwinski
Affiliation:
Department of Nuclear Engineering, Massachusetts Institute of Technology, 77 Massachusetts Av., Cambridge, MA 02139
E. Gelbard
Affiliation:
Reactor Analysis Division, Argonne National Laboratory, 9700 S. Cass Avenue, Argonne, IL 60439
S. Yip
Affiliation:
Department of Nuclear Engineering, Massachusetts Institute of Technology, 77 Massachusetts Av., Cambridge, MA 02139
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Abstract

A computational modeling approach, based on molecular dynamics and related atomistic simulation techniques, is formulated to analyze the confinement of radionuclides in prepared nuclear wasteform for long-term disposal. While the intent is to exploit the ability of simulation to provide a unified treatment of chemical as well as kinetic processes at the molecular level, it is recognized that the problem is too complex to be studied in its entirety at the outset. To demonstrate the feasibility and effectiveness of the atomistic modeling approach, a first step is to determine an equilibrium isotherm for cation exchange, on the premise that a predominant release mechanism is likely to involve ion exchange. As a prototypical application, Cs-Na exchange on sodalite is studied using explicit interatomic potential models. Initial results for the equilibrium Cs concentration in dehydrated sodalite suggest that the effects of frame relaxation need to be taken into account. The present study will be extended to treat an aqueous environment for the loaded wasteform, as well as the effects of radiation damage to the zeolitic framework.

Type
Research Article
Copyright
Copyright © Materials Research Society 1999

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References

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