One of the factors considered within the studies of performance assessment on spent fuel under final repository conditions is the effect of the radiation on its leaching behavior. Radiation from spent fuel can modify some properties of both solid phase and leachant and therefore it would alter the chemical behavior of the near field.
Particularizing in the effect of the radiation on the leachant, it will cause generation of radiolytic species that could change the redox potential of the environment and therefore may bring on variations in the leaching process.
In this work, the chemical analogue utilized was SIMFUEL (natural UO2 doped with non-radioactive elements simulating fission products) and the leachants selected were saline and granite bentonite waters both under initial anoxic conditions. To emulate γ radiation field of a spent fuel, leaching experiments with external 60Co sources in a irradiation facility (Nayade) were performed. Initial dose rate used was 0.014 Gy/s.
Preliminary results indicate that radiation produces an increase of the uranium dissolution rate, being the concentrations measured close to those obtained in oxic atmosphere without radiation field. In addition the solubility solid phases from experimental conditions were calculated, for both granite bentonite water and 5 m NaCl media.
On the other hand, a tentative approach to model the role of γ radiolysis in these SIMFUEL tests has been carried out as well.