OPTIMIZATION OF NEW GLASS MATRICES FOR CONDITIONING OF HIGH LEVEL RADIOACTIVE WASTES

摘要

The incorporation of actinide and actinide surrogates in borosilicate matrix was studied with uranium, cerium and neodymium. This study was carried out on matrix glasses doped respectively by 10 and 30wt% UO_3 while CeO_2, Nd_2O_3 was used to chemically model the actinides in the matrix. The structure was studied by Neutron diffraction combined with Reverse Monte Carlo simulations. For all studied glasses, it was found that the basic network structure consists of tetrahedral SiO_4 units and trigonal BO_3 and tetrahedral BO4 units, forming mixed ~［4］Si-O-~［3］. ~［4］B bond-linkages. The BO_3/BO_4 ratio was also proved by NMR spectroscopy. From the first nearest neighbour distances of U-O, Ce-O, Nd-0 atomic pairs and from the second nearest neighbor atomic pair correlations we found that uranium, cerium, neodymium ions are located in the borosilicate network.