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The Effects of Temperature on the Leaching Behavior of Cement Waste Forms - The Cement/Sodium Sulfate System

Published online by Cambridge University Press:  21 February 2011

Mark Fuhrmann ,
Richard Pietrzak ,
John Heiser ,
Eena-Mai Franz  and
Peter Colombo
Mark Fuhrmann
Affiliation:
Nuclear Waste Research Group, Brookhaven National Laboratory, Upton, NY, 11973.
Richard Pietrzak
Affiliation:
Nuclear Waste Research Group, Brookhaven National Laboratory, Upton, NY, 11973.
John Heiser
Affiliation:
Nuclear Waste Research Group, Brookhaven National Laboratory, Upton, NY, 11973.
Eena-Mai Franz
Affiliation:
Nuclear Waste Research Group, Brookhaven National Laboratory, Upton, NY, 11973.
Peter Colombo
Affiliation:
Nuclear Waste Research Group, Brookhaven National Laboratory, Upton, NY, 11973.
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Abstract

The leaching mechanisms of simulated low-level radioactive waste forms are being determined as support for development of an accelerated leach test. Two approaches are being used: (1) comparison of leaching data with results of a model that describes diffusion from a finite cylinder, and (2) observation of the leaching process at temperatures between 20°C and 65°C. To provide results that can be used for modeling, leaching at elevated temperatures must change neither the leaching mechanism nor the structural controls of leaching such as the porosity. Releases of 137Cs, 85Sr, calcium, sodium and potassium from portland cement containing sodium sulfate, as a simulated evaporator sludge, have been determined under a variety of experimental conditions. Data from the leach tests were compared to model results for diffusion from the finite cylinder. While most leaching appears to be diffusion controlled, notable exceptions occur. For all samples, activation energies ranging between 6 and 11 Kcal/mole have been calculated from the relationship of the effective diffusion coefficient to increasing temperature, close to the expected value of 5 Kcal/mole for diffusion.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 176: Symposium U – Scientific Basis for Nuclear Waste Management XIII , 1989 , 75
Copyright
Copyright © Materials Research Society 1990

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References

REFERENCES

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