The United States is moving closer to selecting a national facility for the underground disposal of highly radioactive materials, including spent fuel from the country's operating nuclear power plants. Acting on a recommendation by US Secretary of Energy Spencer Abraham, President George Bush has recommended to the US Congress Yucca Mountain in Nevada as the site for the repository.
The Yucca Mountain site is located in rock formations about 150 kilometers north of Las Vegas. President Bush's recommendation was based on extensive scientific studies and site evaluations over the past two decades. The site is intended for the safe disposal of used reactor fuel from commercial nuclear power plants and high-level radioactive materials from Department of Energy (DOE) facilities and US defense applications.
International Peer Review. At the request of DOE, an international team of experts convened by the IAEA and Nuclear Energy Agency (NEA) of the Organization for Economic Cooperation and Development conducted a peer review of the site's technical analysis during 2001. The team's report was submitted to DOE in January 2002.
The international peer review was conducted by ten experts over a four-month period last year. The team focused on the methodology of what is called the Total System Performance Assessment for the Site Recommendation (TSPA-SR). The experts concluded that, while presenting room for improvement, the TSPA-SR methodology is soundly based and has been implemented in a competent manner. Moreover, the modelling incorporates many conservatisms.
Overall, the team considered that the implemented performance assessment approach provides "an adequate basis for supporting a statement on likely compliance within the regulatory period of 10,000 years and, accordingly, for the site recommendation decision." Regarding ongoing and future assessments, the team cited growing international consensus for its view that an understanding of the repository system and its performance and how it provides for safety should be emphasized more in future iterations, both during and beyond the regulatory period. Also, further work is required to increase confidence in the robustness of the TSPA. Based on the review, the team's report discusses a number of issues and provides 27 technical recommendations for better supporting the next programmatic decision points.
Underground Disposal. The USA has the world's largest nuclear power programme, with 104 operating and 14 shutdown commercial nuclear power plants at 72 sites in 33 states. According to DOE, spent nuclear fuel and high-level wastes now are safely stored in altogether 131 locations in 39 states.
All the spent nuclear fuel from nuclear power plants in the USA is in solid form, encased hard ceramic pellets that are non-explosive, non-flammable, but highly radioactive. Isolating it and other high-level radioactive wastes from people and the environment is an important and challenging issue for countries that use nuclear power. Underground disposal has been determined by the international scientific community as the preferred option for permanently isolating high-level radioactive wastes in safe and secure engineered repositories.
Besides the USA, many other countries -- including Belgium, Canada, Finland, France, Germany, Japan, Sweden, Switzerland, and the United Kingdom -- have invested in scientific research of deep geologic disposal as a method for isolating highly radioactive waste. They have performed detailed studies, or characterizations, drilling boreholes and exploratory shafts and ramps in underground research laboratories. The data obtained are useful in assessing the safety performance of future nuclear waste repository systems. While no permanent repository has yet been built for spent fuel, Sweden operates an underground Central Interim Storage Facility for Spent Nuclear Fuel, or CLAB, located in Oskarshamn. At the site, the used fuel cools in water for up to 30 years in an underground rock cavern built to contain and isolate it.
If approved and licensed for construction and operation, the Yucca site stands to become the USA's second geological repository for radioactive wastes. In March 1999, the US opened the Waste Isolation Pilot Plant in New Mexico for specific types of radioactive waste that must be safely contained and isolated for centuries. An International Peer Review of WIPP's long-term safety assessment was done at the request of DOE by IAEA and NEA experts in 1997.