The committee also saw copies of slides presented at a GNEP panel session at the U.S. Nuclear Regulatory Commission (USNRC) on March 15, 2007, and GNEP-relevant presentations at the American Chemical Society annual meeting on March 27, 2007. The GNEP Technology Development Plan (TDP) was released on July 25, 2007, after the committee began its peer review stage. Because TDP said that the plans it described did “not necessarily reflect the views and decisions of the Department of Energy,” the committee could not accept it as DOE policy and had to use other references (e.g., reports of the Organisation for Economic Co-operation and Development (OECD) in evaluating the technical aspects of fuel recycling.
In the balance of this chapter, the committee first describes the AFCI program as it existed until 2006 and then describes and evaluates its successor, GNEP. The chapter concludes with the committee’s findings and recommendations.
The United States rejected the idea of recycling spent nuclear fuel during the 1970s because the then-available methods all produced separated plutonium, which can be purified relatively easily into material to make a fission bomb. Similarly, the uranium enrichment process can be misused to generate enough highly enriched uranium to make nuclear weapons. The United States and other countries that are members of the International Atomic Energy Agency (IAEA) have worked to reduce proliferation risks and to rectify the shortcomings identified by the International Nuclear Fuel Cycle Evaluation (IAEA, 1980).
Since the time of that decision not to recycle, other recycling processes have been under development that do not yield separated plutonium. In the United States, processes were worked on, beginning in 2002, under the AFCI, which itself had grown out of the Accelerator Transmutation of Waste program, initiated in 1999. This effort was under the direction of DOE’s Office of Nuclear Energy (NE). The AFCI program was created with the following objectives (DOE, 2005; 2006c, p. 3):
AFCI technology development focuses on reducing the long-term environmental burden of nuclear waste, improving proliferation resistance, and enhancing the use of nuclear fuel resources. The program has one major objective associated with each of these three considerations. The AFCI Program also has a fourth “system management” objective that emphasizes safe and economic nuclear materials management, integrating all of the above considerations.
It is of particular importance to note that the AFCI was to provide an alternative to building the multiple repositories that might be needed for the once-through fuel cycle and to support a growing role for nuclear energy. The published DOE GNEP strategy does not consider the possibility of Yucca Mountain being rejected or of it being accepted and its capacity significantly increased for the storage of more spent fuel. AFCI was to inform the Secretary of Energy about the need for a second repository as early as January 1, 2007, and no later than January 1, 2010, because according to the Nuclear Waste Policy Act, the Secretary is required to report to Congress on that schedule.
To meet its objectives, AFCI examined four fuel cycle strategies (DOE, 2006c, p. 11):
The current U.S. strategy is once-through—all the components of spent fuel are kept together and sent to a geologic repository for disposal.
The second strategy is recycling in thermal reactors only. Uranium in spent fuel and depleted uranium would be disposed of as low-level waste. Transuranic elements, such as plutonium and neptunium, would be recycled several times, deferring the need for a second geologic repository. However, eventually transuranic elements would accumulate and would require geologic disposal. Long-lived fission products would also go to geologic disposal. Short-lived fission products would be first stored and ultimately disposed of as low-level waste. This strategy would use existing types of nuclear power plants, which are all thermal reactors.
The third strategy is sustained recycle with a symbiotic mix of thermal and fast reactors, recycling transuranic elements from spent fuel repeatedly until destroyed. The introduction of fast reactors makes this strategy sustainable from the repository standpoint; the accumulation of transuranic elements during repeated recycle passes is controlled and limited by fast reactors serving as transuranic element burners. Essentially no transuranic elements would go to geologic disposal, only processing losses. Uranium and fission products would be disposed of as with thermal recycling. This strategy requires a significant, but minority, fraction of nuclear power plants to be fast reactors, which are being researched by the Generation IV Nuclear Energy Systems initiative.
The fourth strategy is sustained recycle with fast reactors, recycling both uranium and transuranic elements repeatedly until all energy is extracted. Phasing out thermal reactors in favor of fast reactors means that all types of uranium ultimately serve as fuel; thus this strategy is sustainable both in terms of repository constraints and in terms of uranium ore resources. Essentially no uranium or transuranic elements would be wasted, only processing losses. As with other recycle strategies, long-lived fission products would tend to
For AFCI, Comparison Report, FY 2005, May 2005 (DOE, 2005); Comparison Report, FY 2006 Update, July 2006 (DOE, 2006c); and Status Report for FY 2006, February 2006 (DOE, 2006a).
For GNEP, Mission Need for GNEP, approved on March 22, 2006 (DOE, 2006b); GNEP Implementation Strategy, November 2006 (DOE, 2006d); and GNEP Strategic Plan, January 2007 (DOE, 2007).