Community Research and Development Information Service - CORDIS


UO(2) containing short-lived alpha-emitters, the so-called alpha -doped Uo(2), can simulate type (i.e. alpha - decay) and level of activity of spent fuel at the time when it might become exposed to groundwater in a geologic repository during storage. This allows studying alpha -radiolysis effects on the dissolution of the fuel matrix. Additionally, UO(2) with high concentrations of alpha-emitters accumulate, during experimentally acceptable short times, the amount of decays, hence of property modifications, corresponding to long storage times for spent fuel.

UO(2) containing ~10 and ~ 0.1 wt. % (238)pu was fabricated and tested. Leaching experiments in deionized water under un-aerated conditions, with continuous monitoring of the evolution of the redox potential and pH in the leaching solutions, were performed. The Eh measurements showed a fast increase of the redox potential in the case of the material with the highest alpha-activity, while the UO(2) containing ~ 0.1 wt. % (238)pu increased its potential more slowly. The redox potential for undoped UO2 decreased steadily during the experiment. As previously observed, higher fractions of U were released in the case of ß-doped UO(2) compared to undoped UO(2). The fractions of U and Pu released during leaching from the alpha-doped materials were very similar, suggesting that congruent dissolution occurred. After leaching times longer than 10 h, only dissolved species were present in the solutions. Under these experimental conditions, characterized by relatively low values of the ratio sample surface/leachant volume, a dependence of the released amounts on the alpha-activity of the samples was observed.

Periodical measurements of parameters like hardness, showed a rapid build-up of radiation damage in the material with the high a-activity. After more than two years, noticeable changes, namely an increase of the hardness, have begun to be observed also for the material with the low concentration of (238)pu.

Additional information

Authors: RONDINELLA V, JRC Institute for Transuranium Elements, Karlsruhe (DE);MATZKE H, JRC Institute for Transuranium Elements, Karlsruhe (DE);COBOS J, JRC Institute for Transuranium Elements, Karlsruhe (DE);WISS T, JRC Institute for Transuranium Elements, Karlsruhe (DE);CARBOL P, JRC Institute for Transuranium Elements, Karlsruhe (DE);SOLATIE D, JRC Institute for Transuranium Elements, Karlsruhe (DE)
Bibliographic Reference: An oral report given at: 24th International Symposium on the Scientific Basis for Nuclear Waste Management. Held at: Sydney (AU), 27-31 August 2000
Record Number: 200013176 / Last updated on: 2001-03-20
Original language: en
Available languages: en