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Influence of Redox Environments on the Geochemical Behaviour of Radionuclides

Published online by Cambridge University Press:  28 February 2011

G. Bidoglio ,
A. Avogadro  and
A. De Plano
G. Bidoglio
Affiliation:
Commission of the European Communities, Joint Research Centre, Ispra Establishment, Radiochemistry and Nuclear Chemistry Division, 21020 ISPRA (VA) Italy
A. Avogadro
Affiliation:
Commission of the European Communities, Joint Research Centre, Ispra Establishment, Radiochemistry and Nuclear Chemistry Division, 21020 ISPRA (VA) Italy
A. De Plano
Affiliation:
Commission of the European Communities, Joint Research Centre, Ispra Establishment, Radiochemistry and Nuclear Chemistry Division, 21020 ISPRA (VA) Italy
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Abstract

Studies were carried out on the effect of redox conditions on the release from simulated vitrified HLW of Np-237, Pu-238 and Tc-99 and their migration through columns packed with site-specific porous material representative of clay and salt aquifers. Results obtained under oxic and anoxic conditions are compared. The release rates of Np, Pu and Tc were found to be lower in the absence of air than with oxygenated groundwaters. Speciation studies showed that neptunium and technetium were released in the oxidized forms Np(V) and Tc(VII) even under the investigated anoxic conditions where reduced species are thermodynamically more stable. In spite of that, a stronger interaction was observed when the leachate was passed through the column in the absence of air. A surface reduction process accounts for the observed behaviour. Under more reducing conditions, plutonium appears to be present in the tetravalent state in colloidal form.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 50: Symposium STOCKHOLM – Scientific Basis for Nuclear Waste Management IX , 1985 , 709
Copyright
Copyright © Materials Research Society 1985

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