INFLUENCE OF REDOX ENVIRONMENTS ON THE GEOCHEMICAL BEHAVIOUR OF RADIONUCLIDES
Studies were carried out on the effect of redox conditions on the release from simulated vitrified HLW of 237-Np, 238-Pu and 99-Tc 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 a column in the absence of air. A surface reduction process accounts for the observed behaviour. Under most reduced conditions, plutonium appears to be present in the tetravalent state in colloidal form.
Bibliographic Reference: SCIENTIFIC BASIS FOR NUCLEAR WASTE MANAGEMENT, STOCKHOLM (SWEDEN), SEPT. 9-11, 1985 WRITE TO CEC LUXEMBOURG, DG XIII/A2, POB 1907 MENTIONING PAPER E 32285 ORA
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Record Number: 1989124132400 / Last updated on: 1987-01-01
Available languages: en