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--> 5 Concluding Observations The primary focus of this report is on options for treating aluminum spent fuel. However, spent fuel treatment is just one component of a much larger and complex aluminum spent fuel disposal program, a program that is slated to last for about 40 years and cost in excess of $2 billion. During the course of this study it has become increasingly clear that sound decisions on treatment options cannot be made in isolation of this larger program. This concluding chapter offers some general observations about the overall program and how it impacts the treatment selection process, and also offers some suggestions on how DOE-Savannah River might use this knowledge to make more effective treatment selection decisions. The aluminum spent fuel disposal program is a complex web of activities at multiple sites around the world, ranging from operations at foreign and domestic research reactors that generate aluminum spent fuel to the repository development program at Yucca Mountain. Several parties have responsibilities for activities that take place in this program, and the decisions made by one party can have significant impacts on costs, schedules, and current or planned operations elsewhere in the program. For the following discussion, it is useful to think of the aluminum spent-fuel disposal program as being comprised of the components shown in Table 5.1. The "front end" of the program involves the generation of spent fuel in the foreign and domestic research reactors, an activity that is expected to continue until at least 2035. The "back end" of the program involves the emplacement of treated spent fuel in the repository and the decontamination and decommissioning (D&D) or reuse of the treatment facilities at Savannah River, activities that are expected to last well into the twenty-first century.
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--> An important observation that can be made from inspection of Table 5.1 is that DOE-Savannah River has little if any control over the front and back ends of this program (i.e., components 1, 8, and 9 in Table 5.1) and limited control over components 2 and 7. It does, however, have the responsibility for ensuring that the other components of the program (i.e., components 3-6 in Table 5.1) are compatible with the front and back ends, even though compatibility requirements are not well defined at present. In particular, DOE-Savannah River must select one or more treatment options for aluminum spent fuel that will meet repository waste acceptance criteria, which have yet to be finalized; design treatment and storage facilities that are sized appropriately to waste streams, which are subject to future change; and provide for interim storage of the processed waste until the repository, which is yet to be designed, licensed, or constructed, is able to accept it. The spent fuel disposal program is a systems problem in the classic sense. It involves several interacting components, each associated with different programmatic factors (e.g., cost, time, safety, policy constraints), multiple responsible parties, and different levels of uncertainty (e.g., the right-most column in Table 5.1). The selection of aluminum spent fuel treatment options in the face of such uncertainties calls for a phased strategy in which critical programmatic decisions—that is, decisions that involve major program directions and commitments of funds-are made and implemented when the information needed to base sound choices becomes available. The acquisition of information for decision making also is an important part of the phased-strategy approach, both the acquisition of existing data from third-party sources and the generation of new data to fill information gaps. Of course, the phased strategy recognizes that there may be trade-offs between information acquisition and costs of delayed decisions and seeks to maximize the former and minimize the latter. In the context of the aluminum spent fuel treatment activities at the Department of Energy's (DOE's) Savannah River site, the primary
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--> TABLE 5.1 Components of Aluminum Spent Fuel Program Program Component Responsible Parties Comments 1. Generation of spent fuel Reactor owners Future spent fuel generation will be affected by changes in operating policies, externally imposed regulations, and economic conditions 2. Spent fuel return to SRS Reactor owners and DOE-Savannah River Currently limited by number of shipping casks available to aluminum spent fuel program 3. Spent fuel receipt at SRS DOE-Savannah River Currently limited by capacities of receiving facilities at Savannah River 4. Spent fuel storage at SRS DOE-Savannah River Currently limited by availability of wet basin storage (L-Basin and RBOF) at Savannah River 5. Spent fuel treatment at SRS DOE-Savannah River Options limited by externally imposed waste form requirements, other policy requirements, and cost and schedule constraints 6. Interim storage at SRS DOE-Savannah River Currently limited by availability of storage space at Savannah River
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--> Program Component Responsible Parties Comments 7. Transportation to repository DOE-Savannah River and DOE-Yucca Mountain Will be limited by availability of shipping capacity at Savannah River and receiving capacity at DOE-Yucca Mountain 8. Storage at, and emplacement in, the repository DOE-Yucca Mountain Will be limited by availability of storage and emplacement capacity at the repository 9. D&D or reuse of treatment and storage facilities at SRS DOE Office of Environmental Management, Environmental Restoration Program Will depend on the nature of the treatment facilities and future needs at Savannah River Notes: SRS = Savannah River site; RBOF = Receiving Basin for Offsite Fuels.
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--> objectives of the phased strategy should be to maximize the probability of program success, minimize overall costs, and protect the program against the down-side risks from changes over which it has little or no control. The major programmatic decisions that must be made by DOE-Savannah River include the selection of one or more options for treating aluminum spent fuel and also the selection of a design for the treatment, storage, and shipping (TSS) facilities. The criteria for the decision-making process include the effectiveness of the treatment process, cost, schedule, compliance with applicable environmental health and safety standards, and consistency with other applicable policies. The options selected and facilities constructed also must be matched appropriately to the front (spent fuel generation) and back (disposal and D&D) ends of the overall disposal program (Table 5.1). Phased Decision and Implementation Strategy for Treatment Option Selection DOE-Savannah River appears to recognize the importance of a phased decision-making strategy and is already applying it to individual parts of its program. However, a systems-oriented strategy is needed in the treatment program to ensure that technically sound and cost-effective decisions are made and implemented in a timely manner. Several examples of important considerations for a phased strategy of treatment option selection are summarized in Table 5.2 and discussed below. These examples are presented for illustrative purposes only and do not necessarily represent all of the significant considerations that apply to this program—although they are representative of the significant considerations.
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--> Spent Fuel Generation The quantity and type of aluminum spent fuel to be received and treated at Savannah River is one of the most significant factors in selecting a treatment option. Yet based on the information received during the course of this study, DOE-Savannah River does not appear to have a reliable estimate of the total inventory, particularly that part of the inventory in the "tail" of the receipt schedule shown in Figure 5.1. Nor does DOE appear to have considered the full range of scheduling options for returning this fuel to Savannah River for treatment. With the one exception noted in Chapter 4, DOE-Savannah River appears to have taken the return receipt schedule shown in Figure 5.1 as a given and has done relatively little thinking to date about how changes in this schedule could impact the treatment program and its cost.1 The aluminum spent fuel inventory can be divided into two components for the purposes of selecting a treatment option. The first component is the spent fuel that now exists at DOE-Savannah River or in offsite locations or that is likely to exist and be available for shipment to Savannah River by about 2015. This inventory would include all of the aluminum spent fuel now in storage at Savannah River, all of the foreign research reactor fuel2 the aluminum spent fuel now in storage at the Idaho Engineering and Environmental Laboratory (INEEL), and other domestic research reactor fuel that will be generated and available for shipment prior to about 2015 (Figure 5.1). This might be referred to as legacy fuel. The second component is the fuel that will be available for shipment to Savannah River after about 2015. According to Figure 5.1, 1 Although it appears from the most recent program update (WSRC, 1998) that DOE-Savannah River is beginning to incorporate spent fuel receipt schedule planning in its treatment option selection decision. 2 As shown in Figure 5.1, all of the foreign research reactor fuel is scheduled for shipment to Savannah River by 2009. No new shipments are expected to be added to this inventory.
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--> TABLE 5.2 Objectives and Constraints in Aluminum Spent Fuel Program Program Component Objectives Constraints Major Uncertainties Generation of spent fuel Because treatment options and facility costs will be determined by size and characteristics of spent fuel inventory to be received at Savannah River, do not make major programmatic decisions that involve assumptions about the part of the inventory that is poorly constrained BUT do consider options for treating that part of the inventory that is presently in storage at SRS or that will be received there in the next few years The size of the post-2015 spent fuel inventory Spent fuel receipt at SRS Because the cost of time is so expensive, accelerate the return of aluminum spent fuel to SRS BUT not so quickly that new receipt or storage facilities are required Maximum receipt and storage capabilities at SRS Spent fuel storage at SRS Given that dry storage is less expensive and has fewer requirements for maintenance and servicing, do not rewet any fuel shipped dry to Savannah River BUT review all dry fuel shipments for safety, and treat damaged and degraded fuel by conventional reprocessing Condition of fuel shipped to SRS Given that dry storage is less expensive and has fewer requirements for maintenance and servicing, proceed to treat the fuel in wet storage as soon as possible BUT make sure that treatment will produce an acceptable repository waste form so that retreatment is not required Acceptability of some aluminum spent fuels for direct co-disposal
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--> Program component Objectives Constraints Major Uncertainties Spent fuel treatment Arrange to conventionally reprocess as soon as possible all fuel that has a health- or safety-hazard label BUT do not limit conventional reprocessing to today's hazard labels; include all fuel likely to pick up such a label within the project time horizon (e.g., if it will deteriorate within the operational life of the Canyons, reprocess it now) Amount of fuel that will require conventional reprocessing for safety reasons Arrange to conventionally reprocess as soon as possible odd-sized fuel that will be difficult to treat by direct co-disposal BUT do not treat this fuel at the expense of the hazard labels Policy acceptability of conventional reprocessing Cost of time is so significant that it may make economic sense to treat all fuel now with a process that will ensure an acceptable waste form BUT not if this approach does not save time and money in the long run Acceptability of some aluminum spent fuels for direct co-disposal Treatment option selected should produce an acceptable waste form BUT do not be restrained from considering treatment options that produces an untested waste form if an option is advantageous for other reasons Acceptability of melt and dilute waste form
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--> Program Component Objectives Constraints Major Uncertainties D&D or reuse of treatment and storage facilities at Savannah River Modify current facilities at SRS to handle, treat, and interim-store aluminum spent fuel BUT not if this approach does not save time and money in the long run D&D costs Overall system Consider the trade-off among process costs, container costs, storage costs, shipping costs, and repository costs BUT recognize that the cost of time may void any other perceived cost benefits Overall costs in light of the foregoing constraints Note: SRS = Savannah River site.
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--> Figure 5.1 Projected receipts and transfers of aluminum spent fuel at Savannah River. NOTE: FRR = foreign research reactor fuel; DRR = domestic research reactor fuel; HFIR = High-Flux Isotope Reactor fuel; from INEEL = aluminum spent fuel now in storage at the Idaho National Engineering and Environmental Laboratory that will be shipped to Savannah River for treatment; to INEEL = non-aluminum spent fuel at Savannah River that will be shipped to INEEL for treatment; to repository = treated aluminum spent fuel that will be shipped to a repository for disposal; SRS = Savannah River Site. SOURCE: WSRC (1998), Figure 2.
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--> this would include only HFIR3 and domestic research reactor fuel and probably represents spent fuel that is not yet in existence. This might be referred to as future fuel. The grouping of fuel into these two components is suggested because the inventory of aluminum spent fuel in the second category appears to be poorly defined.4 Much of this fuel has not yet been fabricated or shipped to the reactors where it will be used. Changes in the need for research reactor capacity, changes in the number of operating reactors, or changes in future fuel designs and materials could decrease the amount of generated spent fuel. This could have a significant impact on the size and cost of treatment facilities and the treatment technologies selected. Given that the first component comprises the great majority of the total inventory of aluminum spent fuel to be treated at Savannah River, any facilities constructed to treat this component will likely be more than adequate to handle the post-2015 inventory. Consequently, DOE-Savannah River should be able to tailor its decisions on treatment options and facilities to the legacy component of the aluminum spent fuel inventory, and at the same time it can obtain additional information to improve the estimates of the post-2015 inventory for a later treatment decision. Spent Fuel Receipt and Storage As part of the phased decision strategy on the treatment option for aluminum spent fuel, the fuel receipt and storage schedule will have to be considered, and one of the important programmatic factors in this 3 High Flux Isotope Reactor, located at the DOE Oak Ridge site. 4 The estimates of spent fuel receipt rates beyond about 2010 (Figure 5.1) are based on historical receipt rates and do not take into account future decisions concerning reactor operations, such as decisions to shut down reactors as they reach the ends of their operating lives.
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--> schedule is the high cost of time.5 The prompt shipment of all aluminum spent fuel to Savannah River for treatment might require the purchase of additional shipping casks but could significantly reduce overall costs, especially if the pre-2015 inventory could be returned to Savannah River in time for treatment by conventional reprocessing as discussed below. DOE-Savannah River has recognized the potential advantages of accelerating fuel returns and is beginning to consider such options in its program planning as evidenced by its most recent program update (WSRC, 1998). There is, however, an important trade-off between accelerated receipt schedules and the cost of handling and storage facilities at Savannah River, so shipment and treatment must be phased to minimize the need for new facilities. Additionally, given the high cost of operating the wet basins, they need to be emptied as quickly as possible. Decisions on receipt and storage rates will depend to a great extent on the treatment option(s) selected, as noted below. Treatment and Interim Storage There does not appear to be enough information at present to determine the acceptability of some of the options for treating aluminum spent fuel. As noted in Chapter 3, some aluminum spent fuel may not meet waste acceptance criteria for direct co-disposal in the repository. Also, for policy reasons, conventional reprocessing may be limited to aluminum spent fuel that represents health or safety hazards, and the reprocessing facilities at Savannah River may not be available after 2002. 5 The cost of time can be thought of as the operational costs that are unrelated to actual production activities. These would include management and administrative costs, costs of supporting workers in a stand-by mode, and other operational costs that are time related rather than production or throughput related, for example, certain types of maintenance costs. To the first order, these operational costs are fixed per unit of time, consequently, cost is approximately proportional to time.
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--> DOE-Savannah River must fill these information gaps before a treatment option can be selected. Based on information received by the P.I. during the course of this study, there does not appear to be a technical basis for rejecting conventional reprocessing as an option for treating of aluminum spent fuel from foreign and domestic research reactors. Conventional reprocessing is a proven and reliable spent fuel treatment technology based on over 300 plant-years of operation worldwide, and the necessary treatment facilities (the F and H Canyons and the Defense Waste Processing Facility [DWPF]) are operating at Savannah River and are being used to treat aluminum spent fuel from research and production reactors. The alternative cost study prepared by Westinghouse Savannah River Company (WSRC, 1997b) suggested that conventional reprocessing was a cost-effective treatment option when compared with direct co-disposal and melt-and-dilute treatment, the two primary treatment alternatives considered by the Task Team. However, the cost estimates for these three treatment alternatives have not been independently validated in this or any other study. Although it is difficult to make quantitative comparisons between a proven treatment technology such as conventional reprocessing and some of the other unproven treatment technologies considered by the Task Team, it is clear that the cost, performance, and safety of unproven technologies have much greater uncertainties than those of a demonstrated technology such as reprocessing. The common-basis cost and performance comparison of the two primary treatment alternatives (direct co-disposal and melt and dilute treatment) and conventional reprocessing, which was recommended in Chapter 2 of this report, will enable DOE-Savannah River to determine whether conventional reprocessing is an appropriate treatment option for this fuel. The concern with conventional processing appears to be mainly one of policy and is related to the use of reprocessing for waste
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--> management generally rather than any specific concern about reprocessing this particular fuel type. Current U.S. nonproliferation policy does not encourage the civil use of plutonium. Accordingly, the United States ''does not itself engage in plutonium reprocessing for either nuclear power or nuclear explosive purposes."6 The P.I. notes that plutonium separation is not a significant problem with conventional reprocessing of enriched aluminum spent fuel from research reactors. There is less plutonium in this fuel in comparison to commercial spent fuel owing to its high 235U enrichment, and separation of plutonium is not a required part of reprocessing treatment. The plutonium can be left in the liquid waste stream along with the fission products for later vitrification in glass. For aluminum spent fuel, the 235U separated during conventional processing represents a potential proliferation hazard, but it can be diluted with 238U within the reprocessing facility to make LEU. Moreover, Savannah River is a weapons material secure site and will remain so for the duration of this program. The reprocessing of aluminum spent fuel also does not appear to be in conflict with the DOE decision to phase out reprocessing at Savannah River (DOE, 1992a). The Highly Enriched Uranium Task Force noted in its predecisional draft report (DOE, 1992b; see Chapter 2) that the need for reprocessing for long-term DOE spent fuel management was unclear at present and that DOE should evaluate the near-term operational requirements to bring its facilities to a condition for transfer to the Office of Environmental Management for potential future operations. Indeed, as noted elsewhere in this report, DOE has or plans to reprocess some of its aluminum spent fuel in the Canyons at Savannah River because of safety concerns. 6 The quote is taken from the White House Fact Sheet entitled Nonproliferation and Export Control Policy dated September 27, 1993. The fact sheet is based on Presidential Decision Directive 13, which is classified and was not reviewed in this study.
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--> Additionally, the final environmental impact statement (EIS) for foreign research reactor fuel notes that the use of conventional reprocessing for treatment of foreign research reactor fuel would not be inconsistent with current U.S. policy (DOE, 1996c, p. 24): DOE is aware that the inclusion of chemical separation [conventional reprocessing] within the preferred alternative could be interpreted by some nations, organizations and persons as a signal of endorsement of the use of reprocessing as a routine method of waste management for spent nuclear fuel or a reversal of U.S. policy on reprocessing. This would not be an accurate interpretation. The U.S. policy regarding reprocessing was established in Presidential Decision Directive 13. DOE and the Department of State have determined that this preferred alternative is not inconsistent with that policy. . . . The independent study7 [to be undertaken by DOE] will review the policy, technology, cost and schedule implications for reprocessing foreign research reactor spent nuclear fuel to determine whether reprocessing of foreign research reactor spent nuclear fuel is justified for other than health and safety reasons. 7 As noted in Chapter 2, the foreign research reactor EIS (DOE, 1996c) called for DOE to commission or conduct an independent study of the nonproliferation and other implications of reprocessing spent nuclear fuel from foreign research reactors. Based on the description of this ongoing study, which was provided by Jon Wolfstal of DOE's Office of Arms Control and Nonproliferation at the second information-gathering session, it is an in-house study rather than a commissioned independent study. See additional comments by consultant David Rossin in Appendix D.
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--> The acceptability of conventional processing might be increased if it were redesigned as a reprocess-and-dilute operation, in which spent fuel is conventionally reprocessed and the separated 235U is diluted with 238U to produce low enriched uranium (LEU) before it leaves reprocessing facility.8 In the event that conventional processing is not found to be acceptable, it may still be possible to processes the degraded and damaged fuel (i.e., health and safety hazard "labels") as it is received at Savannah River and perhaps the odd fuel sizes that would be expensive to treat by other methods. As noted in Table 5.2, the definition of labeled fuel should be expanded to include damaged and degraded fuel that will be received in future shipments to Savannah River and fuel in danger of deteriorating while in storage at Savannah River. If conventional reprocessing is not acceptable, then another treatment option will have to be used to treat the pre-2015 inventory of aluminum spent fuel. The selection of a treatment option should be based on a complete systems lifetime cost comparison of those options that meet regulatory requirements. According to the system cost estimates provided in the alternative cost study (WSRC, 1997b; see Table 4.3 in this report), either treatment option will entail about the same costs (the higher costs of melt and dilute treatment are offset by the higher disposal costs for direct co-disposal). Thus, the treatment option selected will depend to a great extent on the acceptability of the waste form for disposal in the repository. All else being equal, the high cost of time may favor the selection of melt and dilute treatment because the acceptability of a direct co-disposal waste form for some aluminum spent fuel is potentially problematical (Chapter 3). Melt and dilute treatment will entail more handling and processing of the fuel, but the waste form characteristics can be altered to make it suitable for repository disposal and, additionally, fewer waste containers will be produced. The cost of a TSS facility to support any of the treatment options may be reduced significantly by phasing receipt and treatment of spent 8 This dilution could in fact be done at almost any step of the process.
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--> fuel or by utilizing existing facilities. For example, if conventional processing treatment is selected, it might be possible to process the pre-2015 inventory by utilizing one or both of the existing wet basins for all storage. If additional storage space is needed, it may be more cost-effective to modify an existing facility at the Savannah River site as an off-loading facility and to coordinate fuel receipt and processing schedules so that additional new storage is not required and double handling9 of the fuel is minimized. Similarly, it may be possible to modify existing facilities for melt and dilute or direct co-disposal treatment. For direct co-disposal treatment, it also might be possible to reduce the size of the TSS facility by drying and packaging, at INEEL, the aluminum spent fuel now in storage at that site—perhaps in the facility that will be built to process the zircalloy fuel now stored there. It does not appear to be optimum from the standpoint of either safety10 or cost to ship the fuel from INEEL to Savannah River for drying and packaging and then to ship the packaged fuel from Savannah River to the repository for disposal. Some renegotiation of current agreements with the State of Idaho may be required to pursue this treatment option. DOE-Savannah River recognizes that a repository may not be available to receive the treated fuel well into the twenty-first century and is prudently planning for several decades of onsite interim storage. Dry interim storage has lower operating costs and requires less maintenance and servicing than wet storage, the current storage medium for unprocessed spent fuel. Thus, it would be advantageous to treat the spent fuel as soon as possible and to put the road-ready canisters into interim storage until they can be shipped to the repository. Of course, the smaller the number of treated canisters, the less expensive it will be to construct 9 For example, moving the fuel from the receiving facility into wet storage, then removing the fuel from wet storage at a later date to treat it. 10 The risk of a conventional traffic accident during fuel shipping operations will probably dominate the transportation risk.
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--> and maintain an interim storage facility. As noted above, it might even be possible to modify existing facilities, such as a drained wet basin, for such storage. Transport and Repository Disposal There appears to be little flexibility on decision-making in the transport and repository disposal parts of the system. The shipping schedule for treated aluminum spent fuel will be determined by the repository program, and the treatment option selected will determine the number of canisters to be shipped. Transportation and disposal costs will be lowest for those treatment options that produce fewer numbers of canisters. Of course, total systems costs will be reduced by shipping the fuel to the repository as soon as practical. Decontamination and Decommissioning Even though the D&D costs of facilities built to receive, handle, treat, and store aluminum spent fuel at Savannah River will not be charged directly to the spent fuel treatment component of the program, the costs will be borne ultimately by U.S. taxpayers. Thus, the decision strategy should consider the costs of D&D as part of the total life-cycle costs of the treatment program. The use of current facilities to treat the aluminum spent fuel (e.g., use of the Canyons and the DWPF for conventional reprocessing) or the modification of existing facilities will likely entail the lowest D&D costs. New facilities will entail additional D&D costs. Post-2015 Aluminum Spent Fuel Inventory There does not appear to be any reason at this time to make a decision about the disposition of the post-2015 inventory of aluminum
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--> spent fuel. That inventory could well be different in size (most likely smaller) and composition than currently anticipated, therefore, treatment options that do not appear to be available today may in fact be available when the time comes to treat this fuel. In addition, facilities might become available elsewhere in the DOE complex to deal with this small residual inventory. As suggested previously, additional efforts should be made to obtain better estimates of the size and characteristics of this waste stream before a treatment decision is made. Path Forward DOE-Savannah River is doing a commendable job of collecting data for decision making on many of the individual components of its treatment option selection program. In addition, DOE-Savannah River is in the process of defining a decision strategy for selecting and implementing a treatment option for aluminum spent fuel. The decision strategy is in the early stages of formulation, and the P.I. did not ask for or receive detailed briefings on this strategy during the course of the study. As part of this decision strategy, it is recommended that DOE-Savannah River conduct a complete systems review to identify and understand the relationships among the various components of the aluminum spent fuel disposal program shown in Table 5.1. DOE-Savannah River also is encouraged to apply a phased strategy for selecting and implementing a treatment option for aluminum spent fuel that takes into account the considerations given in Table 5.2 and discussed above. This phased approach will support the analysis required in the environmental impact statement and will lead to a more credible EIS-ROD (record of decision) and a more successful and cost-effective path forward for the aluminum spent fuel treatment program.
Representative terms from entire chapter: