May 2010Key Facts
- All the used nuclear fuel produced by the U.S. nuclear energy industry in 50 years of operation—approximately 62,500 metric tons—would, if stacked end to end, only cover an area the size of a football field to a depth of about 7 yards.
- Used fuel is a solid material that is stored safely and securely at nuclear power plant sites, either in enclosed, steel-lined concrete pools filled with water, or in steel or reinforced concrete containers with steel inner canisters. The U.S. Nuclear Regulatory Commission determined that used fuel could be stored safely at power plant sites or central storage facilities for at least 120 years. However, this storage was never intended to be permanent.
- In 1982, Congress directed the U.S. Department of Energy to build a geologic repository by 1998 for used nuclear fuel and defense program waste. The Nuclear Waste Fund, paid by a fee on electricity consumers, was established to support the civilian part of the program. Congress and President Bush approved Yucca Mountain, Nev., as the repository site in 2002, and DOE submitted a license application to the NRC in 2008. However, the Obama administration has decided to terminate the project. In January, DOE announced the formation of a blue ribbon commission to make recommendations for managing the nation’s high-level radioactive waste. The commission’s interim report is expected in 18 months.
Solid Used Fuel: Small Volumes, Safely Stored
- Advanced technologies are being developed to recycle used nuclear fuel. These technologies would reduce the amount of radioactive byproducts in the material, while recovering valuable energy, but would not completely eliminate the byproducts. Under any used fuel management scenario, disposal of radioactive byproducts in a permanent geologic repository is necessary.
To generate electricity, nuclear power plants use uranium oxide fuel—in the form of small ceramic pellets—that is placed inside metal fuel rods. These rods are grouped into bundles called assemblies. Fission—the splitting of uranium atoms in a chain reaction—produces a tremendous amount of heat energy for the amount of material consumed. This energy is used to boil water into steam, which drives a turbine generator to produce electricity. Every 18 to 24 months, the plant is shut down and about one-third of the fuel, consisting of the oldest fuel assemblies—which have released a considerable amount of energy but have become intensely radioactive as a result of fission—are removed and replaced.
The nation’s 104 commercial nuclear reactors together produce about 2,000 metric tons of used fuel annually. Interim Options: Expanding On-Site Storage
The delay in the construction of the geologic repository mandated by Congress has forced nuclear power plants to store used fuel on site for longer than originally intended. The result is that many nuclear plants are running out of existing storage capacity. When a plant’s used fuel pool nears its designed capacity, a company has two options:
- Re-Racking. Typically, the first choice is to re-rack the used fuel pool, moving the fuel assemblies closer together. Eventually, even re-racked pools reach their capacity. The second option is on-site storage in dry containers licensed by the NRC.
- Dry Containers. About one-half of U.S. nuclear plants are storing used fuel in large, rugged containers made of steel or steel-reinforced concrete. Depending on the design, a container can hold up to 37 pressurized water reactor fuel assemblies or 87 boiling water reactor fuel assemblies. The containers have a 20-year license. After 20 years, with NRC approval, the license could be extended for another 20 to 40 years.
Building a dry storage facility at a plant site requires an initial investment of approximately $10 million to $20 million. Once the facility is operational, it will cost $5 million to $7 million a year for the maintenance and security of the facility and for adding more containers as storage needs grow. These costs are in addition to the fee that electricity consumers pay into the Nuclear Waste Fund.Closing the Nuclear Fuel Cycle
The resurgence of nuclear energy in the United States and around the world has led to a reassessment of the nation’s long-term used fuel management program, including renewed interest in nuclear fuel recycling and advanced nuclear fuel-cycle technologies. These technologies include advanced reprocessing of used nuclear fuel, advanced fuel fabrication and development of new reactor designs that could further minimize byproducts of the uranium fuel cycle. These technologies, taken together, could reduce the volume, heat and radiotoxicity of nuclear waste byproducts requiring disposal.
These advanced technologies will also take advantage of the enormous amount of energy remaining in the fuel rods after they are removed from the reactor. Existing recycling technologies already do this to a certain extent. However, advanced recycling technologies would accomplish a more complete recycling in a way that does not produce nuclear materials that could be diverted to weapons-related activities.
Whether or not the United States decides to pursue recycling, it will still require a permanent repository. All nations that reprocess used fuel, such as France and Japan, also are developing repositories.Centralized Off-Site Storage Facility
Until a recycling facility or a repository is ready to accept used fuel from nuclear power plants, the United States could benefit from centralized interim storage. Interim storage would provide for a more effective and efficient used fuel management system by consolidating the material and optimizing the transportation infrastructure that would be necessary for the eventual movement of the material to a recycling facility or a permanent geologic repository.Safely Transporting Used Nuclear Fuel
Used nuclear fuel will be transported from nuclear power plants to storage, recycling and disposal facilities by rail, truck or barge. The transportation containers used to ship used fuel typically have walls one foot thick, with radiation-shielding materials sandwiched between outer and inner metal shells. Those designed for truck transportation weigh between 25 and 40 tons, while rail containers weigh between 75 and 125 tons, including the weight of the used fuel.Conclusion
Since the 1950s, scientific organizations around the world have examined the issue of radioactive waste management. Most organizations—including the National Academy of Sciences, Office of Technology Assessment, International Atomic Energy Agency, and the Organization for Economic Cooperation and Development’s Nuclear Energy Agency—have reached the same conclusion: the best and safest long-term option for safely managing high-level radioactive waste is deep geologic disposal.
High-level radioactive waste can be disposed of as used fuel directly from nuclear power plants or as a final waste form after the used fuel is recycled.