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Estimation of Ra Concentration in High-level Radioactive Waste Disposal System

Published online by Cambridge University Press:  01 February 2011

Yasushi Yoshida  and
Hideki Yoshikawa
Yasushi Yoshida
Affiliation:
[email protected], Inspection Development Corporation, Tokaimura, Ibaraki, Japan
Hideki Yoshikawa
Affiliation:
[email protected], Japan Atomic Energy Agency, Geological Isolation Reserch and Development Directorate, Tokaimura, Japan
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Abstract

Concentrations of Ra in groundwater was thought to be affected by substitution reactions with alkaline earth elements contained in a mineral, because the concentration of Ra is less than the solubility of known Ra containing phases. The substitution reaction was simulated using a partition coefficient. Calcite is a dominant mineral to react with Ra in a geological disposal system. However, previous identification of reactive layers of calcite or reversibility of the substitution reaction has not been confirmed. A re-distribution experiment was therefore undertaken and it was found that an estimated 21±13 layers near the surface were reactive and within them substitution equilibrium was achieved. Using these results, a model to estimate Ra concentration was established and adopted to analyze Ra migration. The effects of substitution of Ra and Ca were reasonably simulated.

Keywords

RaCachemical substitution
Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 1124: Symposium Q – Scientific Basis for Nuclear Waste Management XXXII , 2008 , 1124-Q07-18
Copyright
Copyright © Materials Research Society 2009

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