Ken Chacey
Director, Office of Spent Fuel Management
DOE

Peter Dirkmaat
Director, Spent Fuel and High-Level Waste
DOE-Idaho

The U.S. Department of Energy's Office of Environmental Management (DOE-EM) faces a complex challenge in implementing a path forward for the disposal of DOE-owned spent nuclear fuel (SNF). This material was generated by past production and test reactor operations and ongoing test reactor and research reactor operations. DOE intends to include DOE-owned SNF in the proposed repository license application to the U.S. Nuclear Regulatory Commission, which is scheduled for submission by 2002. The National Spent Nuclear Fuel Program is responsible for overcoming the technical challenges to manage and prepare this SNF for disposal. This paper reports on DOE's ongoing efforts to ready the inventory of SNF for disposal.

The paper discusses plans, recent initiatives, and accomplishments of the SNF management program with respect to disposal. In particular, it covers the key areas of (1) quality assurance, (2) categorization approach for performance assessments and criticality analysis, and (3) acceptance criteria for the repository licensing. The SNF management program has made significant progress in these three key areas. Progress has also been made in initiating technical discussions with NRC on the disposal strategy.

The DOE-owned SNF inventory includes over 200 different individual types of SNF, far more than commercial industry. These fuels were developed for and operated in many diverse types of reactors over the past 40 years, including reactors for production of nuclear weapons material and research and test reactors. DOE has also assumed ownership of limited quantities of certain commercial SNF in support of research and development activities. Because of the nature of DOE research and development, many of these fuels are unique, one-of-a-kind fuels. Additionally, DOE, in consultation with the Department of State, adopted the Nuclear Weapons Nonproliferation Policy Concerning Foreign Research Reactor Spent Nuclear Fuel (1), which supports the U.S. nuclear weapons nonproliferation objectives to reduce and eventually eliminate world-wide civil commerce in highly enriched uranium (HEU). Under this policy, the U.S. agreed to accept up to 20 metric tons of SNF containing uranium originally enriched in the U.S. from research reactors in 41 countries.

Since the original planning basis of reprocessing DOE-owned SNF for strategic materials was discontinued in 1992, the Department has implemented programs to safely and cost-effectively manage this fuel. A programmatic management strategy was adopted after rigorous environmental analysis (ref 2) to consolidate and manage the SNF at three DOE spent fuel management sites - Hanford, Idaho National Engineering and Environmental Laboratory (INEEL), and Savannah River Site. The current amount of SNF and storage locations are displayed in figure two. The implementation of this strategy has resulted in significant progress in resolution of safety concerns and development of safe and cost-effective interim storage (3, 4, 5). This progress includes resolving over 62 of the 107 identified SNF safety vulnerabilities as a result of completing 424 of 529 corrective action items associated with the storage of spent fuel. An example of corrective actions includes the transfer of all SNF from the INEEL Chemical Processing Plant Bldg 603 north and middle basins to the more modern facility, Building 666, by August 2, 1996. This move involved over 500 fuel elements and was completed four months ahead of schedule.

The planning basis for disposition of DOE-owned SNF is direct disposal in a geologic repository, including the strategic objectives of minimizing characterization costs and treatment requirements. This plan recognizes that a small amount of the SNF may require additional treatment or packaging to meet transportation and repository requirements. To support this disposition plan, DOE-owned SNF is to be incorporated into the viability assessment (VA) of the proposed repository site being performed by the Office of Civilian Radioactive Waste Management (RW). The VA consists of a preliminary design concept for the critical elements of the repository, a total system performance assessment, a plan and cost estimate for completion of the license application, and an estimate of the cost to construct and operate the repository. This disposal strategy will be accomplished through implementing a rigorous Quality Assurance (QA) program, using a categorization approach to manage SNF analyses, and developing acceptance criteria to form the basis for licensing and final acceptance.

The National Spent Nuclear Fuel Program (NSNFP) has implemented a comprehensive Quality Assurance program to ensure that all quality affecting activities associated with preparing DOE-owned SNF for disposal will meet the requirements of the Quality Assurance Requirements Document (DOE/ RW-0333P). Adoption of a RW-0333P based program provides a consistent level of quality between DOE and commercial spent fuel disposal activities, and will thus support meeting the repository licensing requirements of the Nuclear Regulatory Commission (NRC) for DOE-owned SNF. The NSNFP QA program has been audited and accepted for implementation by RW. This approach has provided both organizations a high level of confidence that technical activities related to DOE-owned SNF will meet NRC quality assurance requirements.

Additional QA implementation activities include development and implementation of site specific QA programs to support eventual acceptance of the site's SNF for disposal. Audits and assessments by the NSNFP have resulted in the acceptance of the site programs in 1997 at Oak Ridge National Laboratory and Savannah River Site. The site specific QA programs at Hanford and INEEL are under development and will be implemented in the near future. Site specific programs also include NRC licensing of storage facilities, such as the license transfer for the Fort St. Vrain storage facility and the license submittal for the planned Three Mile Island Dry Storage Project.

There are notable differences between DOE-owned and commercial SNF that need to be incorporated into disposal planning, especially in the areas of total material and variety of material. Although there is a large variety of DOE-owned fuel types, the DOE-owned SNF constitutes a small amount of the total material planned for repository disposal. The Total System Performance Assessment being conducted as part of the VA for the proposed repository uses a base case containing 70,000 metric tons heavy metal (MTHM), composed of 63,000 MTHM of commercial spent fuel, and 7,000 MTHM of DOE-owned SNF and vitrified HLW. Additionally, preliminary analysis indicates that DOE-owned SNF may constitute only one percent of the total repository radionuclide inventory. The areas of variation between commercial and DOE-owned SNF include size, enrichment, and condition. The enrichment of DOE-owned SNF varies widely, from about one percent to greater than 90 percent enrichment, whereas commercial fuel is less than 4 percent enrichment. The burn-up of many DOE fuels tends to be less than commercial fuels. Finally, due to the intended use and nature of the fuel, some DOE fuels have degradation and composition concerns that are not found in commercial spent fuel.

The resulting technical requirements that are being addressed for disposal of DOE-owned SNF include criticality concerns associated with HEU fuels, assessing performance of spent fuel with various fuel compounds and claddings, evaluating potentially pyrophoric metals, and properly accounting for contribution to the total environmental release from all fuels. With over 200 individual fuel types, the cost of performing the analysis required on each type would be staggering. Additionally, the detailed characterization information for each fuel to support individual analysis may not exist since the fuel was originally intended to be reprocessed for extraction of strategic materials and thus did not require the same detailed information as is required by the NRC for the operation of a commercial nuclear power plant.

To support the required analysis, all DOE-owned SNF types have been evaluated and placed into groups for management of the analysis. These groups reflect the similarity in predicted performance of the individual fuel types assigned to each group. This approach will allow for establishing bounding parameters that represent the characteristics of fuels in a group and has been presented in technical meetings to the NRC (6). This categorization approach is being used for managing the analyses in the key areas of performance assessment, criticality analysis, and design basis events. This approach should also minimize characterization costs and thus allow for optimum utilization of the limited DOE resources. Table I displays the categories for the bounding analysis in the key area of performance assessment. The preliminary results of this analysis indicate that the relatively small DOE-owned SNF radionuclide contribution to the repository should result in a correspondingly small contribution to the total radiation dose at the accessible environment boundary. The results from the performance assessment and criticality analyses are discussed in detail in recent publications (7, 8).

The approach for DOE-owned SNF will be to characterize the spent fuel for disposal by the same technical process as is used for commercial spent fuel. There will be notable differences in implementing this technical strategy due to the unique nature of DOE-owned SNF. The characterization information will be used in the iterative process of repository design and performance analysis. Additionally, the information assists in the development of fuel specific acceptance criteria that define the required performance parameters of the fuel (e.g., information associated with criticality, thermal content, and restricted materials). The acceptance criteria thus provides the technical basis for acceptance of SNF by RW from the spent fuel/ High Level Waste providers. The recently developed draft acceptance criteria for DOE-owned SNF will be formally documented in the Waste Acceptance System Requirements Document (WASRD). The acceptance criteria are intended to be revised and updated as needed. A revision is planned for Fiscal Year 1998 to include results of planned analyses addressing technical issues such as criticality control and pyrophoricity.

To provide information for source term calculations without establishing fuel specific requirements, characterization information in addition to that in the acceptance criteria will be required. The identification of all data needed by RW on a prioritized basis for accepting and disposing of DOE-owned SNF will be documented in the RW Data Needs for DOE SNF, with subsequent submittal and verification of data. Unlike commercial SNF, which has extensive characterization data, the acceptance criteria and RW Data Needs for DOE SNF will determine what additional characterization work and related analysis must be done for DOE-owned SNF.

The relationship and effects of the information resulting from the RW Data Needs for DOE SNF are depicted in Figure 3. As shown in this figure, the characterization information provides input to the developed models to predict the waste package degradation and waste form degradation. The subsequent waste package and waste form degradation results provide the predicted environmental results and source terms, which are used for verification of total system performance. Thus the characteristics of the fuel are bounded in the analyses for the repository performance.

Since the acceptance criteria and spent fuel characterization information are used for both overall repository performance analyses and the technical specifications in the Safety Analysis Report, they will provide the basis for the license application. For DOE-owned SNF, the license application will request approval for each of the different categories. Characterization will not be complete for all DOE-owned SNF at the time of license application. This should not impact the NRC license application review nor the subsequent granting of construction authorization. Characterization must be completed adequately to demonstrate compliance with the bounding conditions for each SNF type before the acceptance of the SNF by RW for repository disposal. The acceptance of DOE-owned SNF is not scheduled until as early as 2010, which will provide adequate time to demonstrate this compliance.

In addition to disposal requirements that will be documented in the WASRD, there are key interface design parameters that must be integrated for design development and operation of the transportation and emplacement systems. These interface requirements will ensure compatibility between the canister and associated transportation casks used for transporting DOE-owned SNF to the proposed repository, and the physical handling capabilities of the facility. The NSNFP and RW are currently developing the design parameters for the physical and envelope interfaces, which will be published as the Interface Control Document. The interface data will include such items as external dimensions, canister flanges or connections, weights, and materials. The resulting document provides for systematic flow-down of the disposal system design requirement to assist in the preparations for disposal of DOE-owned SNF.

There are several other activities in the management of DOE-owned SNF that are being coordinated between EM and RW. One such activity is the implementation of the Technical Strategy for the Treatment, Packaging, and Disposal of Aluminum-Based Spent Nuclear Fuel. Other activities include design of transportation casks, and implementation of "road ready" dry storage at INEEL.

Although the characteristics and varieties of the various DOE-owned SNF differ significantly, a technical strategy is being successfully implemented for developing acceptance criteria for DOE-owned SNF. This approach develops acceptance criteria for each fuel group so that the resulting contribution of any specific spent fuel type is properly bounded by the environmental analyses, and so that all spent fuel will meet repository disposal requirements. Additionally, the relatively small quantity of DOE-owned SNF should result in a correspondingly small contribution to the total radiation dose at the accessible environment boundary.

Effective plans have been developed to address the specific technical requirements for DOE-owned SNF for repository acceptance, including criticality requirements associated primarily with the highly-enriched uranium fuels, and with initial and future potential degradation of some fuel types. The Department of Energy is implementing a sound technical approach to ensure that these requirements will be met in a safe and cost-effective manner. The implementation of a rigorous QA program, grouping spent fuel into categories for management of the analyses, and development of acceptance criteria should result in the disposition of DOE-owned SNF on schedule and with minimum risk.

1. Record of Decision on a Nuclear Weapons Nonproliferation Policy Concerning Foreign Research Reactor Spent Nuclear Fuel, Department of Energy, May 13, 1996.

2. Department of Energy Programmatic Spent Nuclear Fuel Management and Idaho National Engineering Laboratory Environmental Restoration and Waste Management Programs Final Environmental Impact Statement, DOE/EIS-0203-F, (April 1995).

3. J. J. JICHA, "DOE-owned Spent Nuclear Fuel Path Forward: Challenges and Options", Waste Management Symposium, Tucson, 1995.

4. G.F. COLE, "Overview of the DOE-owned Spent Nuclear Fuel Program", Waste Management Symposium, Tucson, 1996.

5. DOE-owned Spent Nuclear Fuel Strategic Plan, Rev 1, DOE/SNF/PP-204, Sept 1996.

6. Minutes of the Technical Exchange Meeting on DOE SNF, July 30 1997, NRC, 1997.

7. R. RECHARD, et al., "The Value of Performance Assessment in Developing Acceptance Criteria for Disposal of Spent Nuclear Fuel", Waste Management Symposium, Tucson, 1998.

8. L.L. TAYLOR, et al., "Criticality Issues with Highly-Enriched Fuels in a Repository Environment", Waste Management Symposium, Tucson, 1998.

BACK