Electrometallurgical Techniques for DOE Spent Fuel Treatment: A Status Report on Argonne National Laboratory's R & D Activity Through Spring 1997 (1999)

Committee Attendance: G. Choppin (chair), J. Ahearne, M. Apted, P. Baisden, S. Burstein, E. Flanigen, E. McNeese, J. Sherman, J. Williams, R. Wymer. NRC staff: D. Raber, T. Wong.

Unable to attend: R. Osteryoung.

ANL Attendance: D. Abraham, J. Ackerman, R. Benedict, Y. Chang, M. Golf, D. Keiser, J. Laidler, M. Lewis, S. McDeavitt, C. Pereira, L. Simpson, D. Wronkiewicz.

The committee assembled at Argonne National Laboratory at 8:30 a.m. for discussions with ANL staff. Following welcoming remarks by Yoon Chang (ANL) and Gregory Choppin (Committee Chair), the committee received briefings as described below.

James Laidler (for C. McPheeters) provided an overview of the Materials Disposition Program at ANL. He discussed the U.S. surplus plutonium inventory and described the flow sheet that ANL proposes to employ for plutonium disposition. He summarized FY 1996 R&D activities in this area, particularly in design and testing waste forms, plutonium loading on zeolite, lithium reduction of PuO₂, processing of plutonium-loaded zeolite, and current status of the R&D effort.

James Laidler reported on the status of the Spent Fuel Program, including the development of a flow sheet for treatment of foreign research reactor fuels. Newly devised ANL head-end treatment would allow aluminum-clad fuels to be processed by the electrometallurgical approach. Laidler also discussed ANL's reaction to the committee's previous report.1

Robert Benedict provided the committee with an update of accomplishments at the Fuel Conditioning Facility (ANL-West), including a revised scope for the planned EBR-II demonstration for treating irradiated fuel. Specific information was provided on operations of the electrorefiner and cathode processor, and on both ceramic and metal waste forms.

John Ackerman gave an overview of ANL-East developments on waste forms, with a primary focus on the mineral waste form. His discussion provided an introduction for subsequent presentations on the topic of waste forms. He further described waste form requirements, performance, preparation, and characterization. A development timetable for mineral waste was presented.

Michele Lewis discussed characterization test methods, beginning with an overview of the mineral waste form testing program. She described test methods used in feasibility studies, the ASTM standard leach test employed, screening criteria for the mineral waste form, and mechanical properties that are measured. Other analyses that will be used to evaluate waste forms include determination of radiation and thermal stability and structural characterization by x-ray diffraction and scanning electron microscopy-energy dispersive spectroscopy.

John Ackerman described hot pressing techniques for waste form preparation and progress in waste form development. Information on waste form characteristics was presented, including the effects of hot pressing.

David Wronkiewicz reported preliminary results on qualification studies of the mineral waste form. He described the test methodology, including the product consistency test and the vapor hydration test. Results were presented for zeolite and glass-bonded zeolite.

Candido Pereira presented results on zeolite structural studies, emphasizing the importance of using anhydrous zeolite in waste form preparation. Crystal structure data was presented for both unloaded and loaded zeolite and for samples of loaded zeolite after high-temperature treatment. Ion exchange of plutonium salts was reported, and ion exchange rates and kinetics are being determined for a series of cations. Loaded zeolite has been studied by blending (with additional zeolite) and aqueous washing to distinguish between salt on the zeolite surface and salt trapped in the zeolite cages.

Michael Goff discussed plans for ceramic waste form development at ANL-West, including the use of simulated waste products as well as radioactive materials from spent fuel. He described scale-up issues, the processing of radioactive materials, and the status of the facility and equipment, particularly for hot isostatic pressing.

Candido Pereira provided an update on zeolite column operations. Results were described for processing through zeolite columns followed by hot blending with additional zeolite. Performance was studied as a function of operating temperature, flow rate, and salt composition. Results were presented about zeolite structure following the ion exchange and about interstitial surface salt and methods for its removal. Future tests were outlined, and development of computer models was described.

Sean McDeavitt gave an overview of accomplishments and future plans for metal waste form development at ANL-W. He described basic alloy studies, characterization and performance evaluation (including corrosion and mechanical testing), and process development (particularly for scale-up and extension to radioactive materials).

John Ackerman summarized waste form development activities, emphasizing characterization and scale-up, and noting that the project emphasis has evolved from feasibility to development. He advised the committee that efforts directed toward ultimate qualification of the waste forms are scheduled for later this year (with emphasis on ASTM C 1220-92, Standard Test Method for Static Leaching of Monolithic Waste Forms for Disposal of Radioactive Waste).

Following these discussions, the committee divided into several smaller groups for discussions with ANL staff and among committee members. Several members of the committee visited the laboratories to observe apparatus and equipment employed by ANL. The meeting adjourned for the day at 5:30. The committee reassembled at 7:00 for an informal working dinner.

Attendance: G. Choppin (chair), M. Apted, P. Baisden, S. Burstein, E. Flanigen, E. McNeese, R. Osteryoung, J. Sherman, J. Williams, R. Wymer. NRC staff: D. Raber, T. Wong.

Unable to attend: J. Ahearne.

Two goals were established for the meeting:

1. Develop a draft status report on progress of the ANL R&D activity.

2. Determine if the planned schedule of committee activities remains appropriate.

The committee convened at 8:00 a.m. for a working breakfast. Committee deliberations then began with follow-up discussion on the plutonium report.² This was followed by a discussion of the revised scope of the EBR-II Demonstration Project and its consistency with recommendations contained in the committee's July 1995 report.³ The committee then turned its attention to drafting a progress report on ANL's R&D Program. Before adjourning at 3:00 p.m., the committee discussed options for how to proceed with its task and schedule in view of delays in start-up of hot operations at ANL-West.