The production of commercially available nuclear energy has been mainly based on power reactors using fuel enriched in U-235 (typically the fuel has 95-97% U-238 and 3-5% U-235, natural uranium has 0.72% U-235 by mass). This required the development and implementation of uranium enrichment facilities [7.24]. It was recognized that the energy potential of uranium resources could be increased using “nuclear breeding” where uranium and thorium resources offered an essentially inexhaustible fuel resource. Breeder reactors can produce Pu-239 from U-238 and fast breeders can produce more fissionable fuel than they consume [7.25]. Subsequently, Pu-U and Pu-Th fuels would be used to generate electricity.
These considerations lead to a two stage strategy for future nuclear generation:
• The use of thermal once-through reactors to generate energy and to accumulate plutonium for the start-up of advanced fuel cycles and breeder reactors, being developed concurrently, e.g., breeders; and
• The deployment of breeder reactors and advanced fuel cycles to support large-scale growth of nuclear power to replace, over time, traditional fossil energy sources.
The issue of sustainable development is addressed in programmes aimed at developing advanced nuclear power reactors and deploying new fuel cycle systems. Among them, the most significant are the IAEA’s International Project on Innovative Nuclear Reactors and Fuel Cycles (INPRO, see Subsection 7.3.1) [7.26] and the US initiated Generation IV International Forum (GIF, see Subsection 7.3.2) [7.27]. The future evolution of nuclear power will impact on the quality and quantity of radioactive waste that is generated.
INPRO is based on an IAEA General Conference Resolution in September 2000 and additional resolutions in 2001 and 2002. Additional endorsement came in the UN General Assembly resolutions on the IAEA (A/RES/56/94, 2001 and A/RES/57/9, 2002) that emphasized “the unique role that the Agency can play in developing user requirements and in addressing safeguards, safety and environmental questions for innovative reactors and their fuel cycles” and stressed “the need for international collaboration in the development of innovative nuclear technology”. The Terms of Reference for INPRO were established in November 2000 and progress to date is described in reference [7.28].
The generation of radioactive waste from innovative nuclear reactor technologies is also followed within projects supported by the European Commission within the 5th and 6th framework plans for research and technological development. In 2003, a Thematic Call in the area of “Euratom Research and Training programme on Nuclear Energy” was announced. The call includes an objective to
“determine practical ways of reducing the amount and/or hazard of the waste to be disposed of by partitioning and transmutation and to explore the potential of concepts for nuclear energy to produce less waste” within its scope [7.29]. The purpose of the objective is to assess the benefits and disadvantages of partitioning and transmutation on the fuel cycle as a whole and, in particular, for waste management and geological disposal. The scope of the project mainly includes system studies to evaluate the health, environmental, social and economic benefits (or disadvantages) of partitioning and transmutation applied on an industrial scale to the fuel cycle and establishing performance criteria for the different steps. Within this, all operations and waste streams in the fuel cycle that would be significantly affected by partitioning and transmutation will be addressed.
The U.S. Department of Energy (DOE) prepared a report on advanced fuel initiatives to respond to Congressional direction [7.30]. Congress instructed the DOE to provide answers to several questions related to the spent fuel separations and transmutation research activities. Specifically, Congress directed the DOE to:
• compare chemical and pyroprocessing, accelerator-driven transmutation, and fast reactor transmutation alternatives, including full disclosure of all waste streams;
• estimate the life cycle costs to construct, operate, and decommission and decontaminate all necessary facilities;
• compare the proliferation resistance of the various technologies;
• provide a strategy for siting new processing and disposal facilities that would be required for the various reprocessing and transmutation alternatives;
• use the once-through fuel cycle as presently used in the USA and the amount of spent nuclear fuel presently scheduled for disposal in the geologic repository as the baseline for all comparisons; and
• present the DOE’s strategy for siting the new processing and disposal facilities that would be required for various processing and transmutation alternatives, assuming a capacity sufficient to process the amount of spent fuel presently scheduled for geologic repository.
The information presented in the report reflects the current state of R&D knowledge on separation and transmutation technologies. Regarding disposal, the report states that these questions cannot be answered until the technologies to be employed have been selected and necessary environmental impacts studied. However, the DOE anticipates that any advanced fuel cycle facilities built in the USA would be constructed and operated by the private sector with appropriate incentives that reflect the national benefits of implementing technology approaches to managing nuclear waste.
7.3.1 INPRO
Regarding waste management, INPRO adopts the nine principles as defined the IAEA Safety Fundamentals “The Principles of Radioactive Waste Management [6.2]. From these principles, INPRO defined six user requirements, associated criteria (expressed in the form of 20 indicators and relevant acceptance limits). At this stage of the INPRO, the user requirements are only qualitative. The requirements are:
Predisposal waste management: Intermediate steps between generation of the waste and the end state should be taken as early as reasonably practicable. The design of the steps should ensure that all important technical issues (e.g., heat removal, criticality control, confinement of radioactive material) are addressed. The processes should not inhibit or complicate the achievement of the end state.
End state: For each waste in the energy system, a permanently safe, achievable end state should be defined. The planned energy system should be such that the waste is brought to this end state as soon as reasonably practicable. The end state should be such that, on the basis of credible conservative analysis or demonstrated operation, any release of hazardous materials to the environment will be below that which is acceptable today.
Adverse effects on human health: Waste management systems should be designed to assure that their associated adverse radiological and non-radiological effects on humans are below the levels acceptable today. Because the waste management systems are integral parts of the overall energy system, their designs should be optimized with respect to adverse effects as part of the optimization of the overall energy system.
Adverse effects on the environment: Waste management strategies should be such that the adverse environmental effects from all parts of the energy system and the complete life cycle of facilities are optimized. The cumulative effects over time and space, without regard to national boundaries, should be considered.
Reduction of waste at the source: The energy system should be designed to minimize the generation of wastes and particularly wastes containing long lived toxic components that would be mobile in a repository environment.
Attribution of waste management costs: The costs of managing all wastes in the life cycle should be included in the estimated cost of energy from the energy system, in such a way as to cover the accumulated liability at any stage of the life cycle.
The INPRO report [7.28] also recommends areas for research, development and demonstration (RD&D) that offer particularly good potential for reducing adverse effects due to the presence of long lived radionuclides and indicates objectives and a time requirements for each of them. These RD&D areas are:
• methods for characterizing wastes in the nuclear fuel cycle to reduce occupational exposure, improve efficiency and facilitate showing compliance with waste acceptance;
• waste treatment methods to reduce radiological impact from storage and disposal of waste and to decrease the amount of hazardous material requiring disposal;
• reprocessing of spent fuel to improve waste stream characteristics and to reduce secondary wastes;
• methods to increase the safety of storage;
• partitioning and transmutation to reduce long lived radioactive components in HLW and to enhance the efficiency of partitioning operations;
• geological disposal to demonstrate disposal technologies, to improve geological characterization, to enhance understanding of hydrogeochemical transport processes, to improve long term monitoring technologies and to facilitate the detailed design of geological repositories;
• long term human factor analysis to assess risks associated with waste management systems that require long term institutional controls; and
• design-based comparison of waste arising from proposed advanced reactors and fuel cycles to incorporate safety of waste management and fuel reprocessing in the fuel cycle evaluations.
7.3.2 Generation IV International Forum (GIF)
To advance nuclear energy to meet future energy needs, ten countries - Argentina, Brazil, Canada, France, Japan, the Republic of Korea, the Republic of South Africa, Switzerland, the United Kingdom, and the United States of America - have agreed on a framework for international cooperation in research for a future generation of nuclear energy systems, known as Generation IV [7.31]. The ten countries have joined together to develop next generation nuclear energy systems that can be licensed, constructed, and operated in a manner that will provide competitively priced and reliable energy products while satisfactorily addressing nuclear safety, waste, proliferation, and public perception concerns. The objective for Generation IV nuclear energy systems is to have them available for international deployment about the year 2030, when many of the world’s currently operating nuclear power plants will be at or near the end of their operating licenses.
Beginning in 2000, the countries constituting the GIF began meeting to discuss the research necessary to support next-generation reactors. From those initial meetings a technology roadmap to guide the Generation IV effort was begun [7.32]. The organization and execution of the roadmap became the responsibility of a Roadmap Integration Team that is advised by the Subcommittee on Generation IV Technology Planning of the U.S. Department of Energy’s Nuclear Energy Research Advisory Committee. The roadmap and other planning documents will be the foundation for a set of R&D program plans encompassing the objectives of deploying more mature nuclear energy systems by
2010, developing separations and transmutation technology for reducing existing stores of spent nuclear fuel, and developing next generation nuclear energy systems in the long term.
As preparations for the Generation IV Technology Roadmap began, eight goals for Generation IV were defined in the four broad areas of sustainability, economics, safety and reliability, and proliferation resistance and physical protection. The goals that are most relevant to waste management are:
Sustainability–1. Generation IV nuclear energy systems will provide sustainable energy generation that meets clean air objectives and promotes long term availability of systems and effective fuel utilization for worldwide energy production.
Sustainability–2 Generation IV nuclear energy systems will minimize and manage their nuclear waste and notably reduce the long term stewardship burden, thereby improving protection for the public health and the environment.
The activities of GIF consist of planning activities and, therefore, there are no immediate direct impacts on waste management issues.