Uranium bearing glasses in the silicate and phosphate systems

Abstract

The compositional aspects of high uranium content silicate and phosphate glasses were studied. Highly stable silicate glasses were prepared containing up to 45 wt % UO 2. In the phosphate system comparatively stable glasses with UO 2 contents as high as 40 wt % were produced. An intermediate oxide, such as TiO 2 or Al 2O 3 and/or a modifier, such as Na 2O was required in the preparation of uranium silicate glass. Glasses consisting entirely of urania and phosphorus pentoxide were prepared and the addition of alumina increased the durability of the uranium phosphate glasses. The best glasses from each system were highly devitrification-resistant and virtually insoluble in boiling water and most common reagents. HF attacked glasses in both systems and NaOH decomposed the phosphate glasses but not the silicates. Densities of the glasses ranged up to 3.56 g/cm 3. In general, those glasses with the highest uranium contents had the highest densities. The linear thermal expansion coefficient for a typical silicate glass was 6.8 × 10 −6/°C and for a typical uranium phosphate glass, 5.5 × 10 −6/°C.