Analysis of the CWF samples and evaluation of the resulting data may not be complete at the end of the demonstration program. Hence, meeting the above two success criteria goals may be delayed beyond the end of the demonstration period until analysis and data evaluation can be completed.
Advanced Fabrication. Fabrication technology alternatives to HIP have been considered by ANL. These consist of hot uniaxial pressing (HUP), where the amount of glass is increased to about 25 mass %, and pressureless sintering (PLS), where the amount of glass is increased to about 50 mass %. ANL has stated that it is only using HUP to prepare simulated CWF and is not considering it further. However, pressureless sintering is under development as an alternative to HIP for the postdemonstration period and appears to be an attractive alternative to HIP. PLS would avoid concerns about scale-up in canister size and unresolved safety issues associated with remote HIP in a hot cell.
Conclusion: The committee believes that ANL is taking appropriate steps to coordinate its waste qualification program with the DOE-RW repository program. It remains undemonstrated, however, that direct adaptation of test procedures and models developed for measuring the rate of general corrosion of the matrix of homogeneous, vitrified HLW forms are sufficient for evaluating the performance of the heterogeneous, crystalline CWF under long-term repository conditions.
It is significant that the tests conducted so far by ANL indicate that the rate of corrosion of the CWF is comparable to that of the reference borosilicate glass. It remains to be seen whether this behavior will continue in long-term testing.
Conclusion: These continuing concerns are not expected to jeopardize the timely completion of the EBR-II demonstration project in 1999, but attention should be devoted to their resolution prior to extending the EMT process past the demonstration.
When criteria for acceptance of waste forms for geologic repository placement are adopted by RW, test procedures for the waste forms produced by the electrometallurgical process may require modification. The committee believes, however, that the test procedures used for the MWF and CWF are appropriate for the completion of ANL's demonstration project.