Editors : R.W. Grimes, J.W. Roberts. N.C. Hyatt, W.E. Lee
a1 Immobilization Science Laboratory, Department of Engineering Materials, University of Sheffield, Sir Robert Hadfield Building, Mappin Street, Sheffield, S1 3JD, UK.
Pyrochemical and aqueous processing of impure Pu metal and Pu oxide results in a waste stream that contains calcium, plutonium and americium chlorides (CaCl2, PuCl3 and AmCll3) that tend to form insoluble salt layers on top of melts during vitrification. By adding chlorides to ammonium dihydrogen phosphate, ammonium chloride is evolved during vitrification, leaving behind the Ca, Pu and Am cations as oxides. HfO2 and Sm2O3 were used as surrogates for PuO2 and Am2O3 respectively. The effects of waste loading and melt duration on some basic physical properties for different melt durations were investigated. Synthetic batches containing CaO, HfO2 and Sm2O3 in molar ratios 93.34 : 5.91 : 0.74 respectively, reflecting the waste composition, were mixed with a fixed glass composition of P2O5 (75 mol%) and Fe2O3 (25 mol%). NH4H2PO4 was used as a precursor material. The solubility of calcium, hafnium and samarium oxides into phosphate glasses is reported and elemental analysis of the glasses is compared with expected glass compositions.