Nuclear waste forms glasses

Ewing, R.C. (2001). Nuclear waste form glasses the evaluation of very long-term behaviour. Materials Technology 16 30-36. 

Jercinovic, M. J. Ewing, R. C. 1987. Basaltic Glasses from Iceland and the Deep Sea Natural Analogues to Borosilicate Nuclear Waste-Form Glass. Swedish Nuclear Fuel and Waste Management Co, Stockholm, Technical Report JSS 88-01, 221 p. 

Zhao, D., Li, L., Davis, L. L., Weber, W. J. Ewing, R. C. 2001. Gadolinium borosilicate glass-bonded Gd-silicate apatite A glass-ceramic nuclear waste form for actinides. Materials Research Society Symposium Proceedings, 663, 199-206. 

Malow, G., Lutze, W. Ewing, R. C. 1984. Alteration effects and leach rates of basaltic glasses implications for the long-term stability of nuclear waste form borosilicate glasses. Journal of Non-Crystalline Solids, 67, 305-321. 

Altenhein, F. K., Lutze, W. Malow, G. 1981. The mechanisms for hydrothermal leaching of glass and glass-ceramic nuclear waste forms. In MOORE, J. G. (ed) Scientific Basis for Nuclear Waste Management III. Plenum Press, New York, USA, 363-370. 

Phosphate glasses have also been investigated as nuclear waste forms. These are typically made with nonvolatile, high-valent metals such as Fe, Zr, lanthanides, or Th, sometimes with additions of lead to promote glass formation, for example, Fe-Pb-phosphate glasses. Crystalline waste forms based on the NaZr2(P04)3 NASICON structure (see Section 5.2.1) have also been studied as these can exchange Na for Cs, which is difficult to immobilize. 

In the case of the disposal of high-level light water reactor waste, these wastes intrinsically contain up to 35 wt % rare-earth oxides that could be directly converted to form part of the monazite host matrix. Because Ewing and Wang (this volume) have provided a comparison of the properties of monazite-based waste forms to those of other crystalline host media and nuclear waste phosphate glasses, no further details regarding this application of the rare-earth orthophosphates will be given here. 

The early work on phosphate glasses led to the idea that crystalline phosphates might make extremely durable waste forms, particularly for actinides. The earliest suggestion was for the use of monazite (Boatner 1978, Boatner et al. 1980, McCarthy et al. 1978, 1980). The attractive qualities of monazite as a nuclear waste form are (1) a high solubility for actinides and rare earths (10 to 20 wt %) (2) evidence from natural occurrences of good chemical durability (3) an apparent resistance to radiation damage, as natural monazites are seldom found in the metamict state, despite very high alpha-decay event doses (Boatner and Sales 1988). There have been extensive studies of monazite and apatite as potential waste form phases, and a considerable amount of work on a number of synthetic phosphate phases has been completed. 

Crystalline phosphates and phosphate glasses continue to receive attention as potential hosts for the immobilization and disposal of radionuclides, particularly actinides and waste streams with a high phosphorous content. The principal crystalline phases considered are apatite, silicates with the apatite-structure, and monazite. As has been discussed by Lutze and Ewing (1988a), there are a number of factors that have to be considered in selecting a nuclear waste form. The most important are ... 

Fig. 6.21 High level nuclear waste body composed of solid-waste form (glass), canister, overpack and backfill and buffer disposed deep underground...

Vance, E. R., Carter, M. L., Day, R. A., Begg, B. D., Hart, K. P. Jostsons, A. 1996b. Synroc and Synroc-glass composite waste forms for Hanford HLW immobilization. In Proceedings of the International Topical Meeting on Nuclear and Hazardous Waste Management SPECTRUM 96. American Nuclear Society, Inc. La Grange Park, 2027-2031. 

Gong, W. L., Wang, L. M., Ewing, R. C., Vernaz, E., Bates, J. K. Ebert, W. L. 1998. Analytical electron microscopy study of surface layers formed on the French SON68 nuclear waste glass during vapor hydration at 200°C. Journal of Nuclear Materials, 254, 249-265. 

Gin, S., Ribet, I. Coulliard, M. 2001a. Role and properties of the gel formed during nuclear waste glass alteration Importance of gel formation kinetics. Journal of Nuclear Materials, 298, 1-10. 

Release rate data for radionuclides from fully radioactive waste forms are needed to evaluate the safety of nuclear waste glass. Presently, contact with water is considered the most important release path therefore, the release properties of waste glass in water are of primary concern. 

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