Tests were performed with SON68 glass, doped with Tc-99 and Np-237, in a concentrated suspension of FoCa-clay, made reducing by the addition of iron coupons.
The tests clearly show that the redox potential is the main parameter affecting the radionuclide concentrations and the immobilization of the radionuclides by the clay.
Good reducing conditions, like those obtained by addition of iron coupons in the leach tests, induce very low Np and Tc concentrations in the leachates, lower than the experimental far field concentrations, and lower than the calculated "far-field" solubility of the expected solid phases of Np(IV)and Tc(IV).
Other tests were performed with inactive glasses SON68 and SM539, containing Se, Sn, Zr and Pd, to determine the respective dissolved concentrations in conditions similar to the near field conditions.
The dissolution of the glass does not increase the overall dissolved concentrations of Se, Sn, Zr and Pd above the background concentrations in the simulated near-field. The concentrations are similar to the concentrations measured in the far field, except for Se.
|Number of pages
|Published - Nov 2009
|Studiecentrum voor Kernenergie