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The Importance of Variables and Parameters in Radiolytic Chemical Kinetics Modeling

Published online by Cambridge University Press:  26 February 2011

M. G. Piepho ,
P. J. Turner  and
P. W. Reimus
M. G. Piepho
Affiliation:
Pacific Northwest Laboratory, P.O. Box 999, Ri chi and, WA 99352, U.S.A.
P. J. Turner
Affiliation:
Pacific Northwest Laboratory, P.O. Box 999, Ri chi and, WA 99352, U.S.A.
P. W. Reimus
Affiliation:
Pacific Northwest Laboratory, P.O. Box 999, Ri chi and, WA 99352, U.S.A.
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Abstract

Radiolysis may significantly affect the long-term performance of nuclear waste packages in a geologic repository. Radiolysis of available moisture and air in an unsaturated or saturated environment will create transient species that can significantly change the pH and/or Eh of the available moisture. These changes can influence rates of containment corrosion, waste form dissolution, and radionuclide solubilities and transport.

Many of the pertinent radiochemical reactions are not completely understood, and most of the associated rate constants are poorly characterized. To help identify the important radiochemical reactions, rate constants, species, and environmental conditions, an importance theory code, SWATS (Sensitivity With Adjoint Theory-Sparse version)-LOOPCHEM, has been developed for the radiolytic chemical kinetics model in the radiolysis code LOOPCHEM. The LOOPCHEM code calculates the concentrations of various species in a radiolytic field over time. The SWATS-LOOPCHEM code efficiently calculates: 1) the importance (relative to a defined response of interest) of each species concentration over time, 2) the sensitivity of each parameter of interest, and 3) the importance of each equation in the radiolysis model. The calculated results will be used to guide future experimental and modeling work for determining the importance of radiolysis on waste package performance. A demonstration (the importance of selected concentrations and the sensitivities of selected parameters) of the SWATS-LOOPCHEM code is provided for illustrative purposes, and no attempt is made at this time to interpret the results for waste package performance assessment purposes.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 127: Symposium BERLIN – Scientific Basis for Nuclear Waste Management XII , 1988 , 905
Copyright
Copyright © Materials Research Society 1989

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References

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