knowledge and understanding of the corrosion of waste form glasses that result from future research and development.

3. In the United States there is almost no connection between waste acceptance criteria (essentially a determination of product consistency) and the scientific basis for understanding the long-term behavior of glass waste forms.

4. There is considerable worldwide experience in the vitrification of high level waste, providing a strong basis for proceeding with vitrification technologies; however, a single technology will not solve every waste problem. The properties of any solid (glass, crystalline, or glass-ceramic) depend, to a considerable extent, on composition as well as on the solid's thermal and processing history. The diverse waste streams found in the DOE complex may require (a) extensive pretreatment to develop more narrowly defined compositions for vitrification, (b) the development of alternative waste glass compositions, and/or (c) the development of alternative waste forms.

In summary, the present knowledge of glass properties, particularly corrosion behavior, is considerable, and industrial-scale experience with the vitrification of radioactive waste is impressive. This provides a firm basis for present DOE programs. However, based on what its members heard at the workshop, the steering committee believes that continued research and development to improve waste form performance, as discussed in the body of this report, may lead to substantially reduced risks to the public, reduced costs to the taxpayers, and reduced uncertainty in the regulatory analysis of compliance.