The need for innovative fuel cycles29 December 2001
Nuclear power is at a turning point, with no consensus concerning its future role. We would expect to see a rising trend for nuclear power generation in the near future, but that is not the case.
There are no commitments in North America and Western Europe for construction of new nuclear power plants in the near future, and Germany and Sweden have decided to phase out existing nuclear plants. In addition, although many developing countries around the world have been considering the use of nuclear power for a long time, few have yet done so.
Globally, the number of power plant construction starts peaked in the 1970s, and connections to the grid in the 1980s, but current levels of both are far below the values achieved earlier. There is no indication that this global picture will change significantly in the coming decade.
The main issues hindering further global nuclear power growth are different for various reasons. Nuclear power development faces serious challenges of an economic and political nature in the two regions with the maximum experience in nuclear power development: North America and western Europe. In developing countries, the main issues are lack of adequate infrastructure, particularly in the back-end of the fuel cycle, lack of expertise in nuclear technology and its safety culture, as well as financing issues.
Political concerns on nuclear waste, safety and non-proliferation are also hindering the development of nuclear power. If nuclear power is to contribute significantly to meeting future energy demands, these issues, real or perceived, must be addressed. This is a particular challenge for developing countries that need electricity to mitigate the burdens of poverty and meet basic human needs. More must be done to assist developing countries interested in pursuing the nuclear option for electricity generation.
Evolutionary design advanced reactors are very important for the continuation of nuclear power development in the near future. Nevertheless, they can not be considered from an economic point of view as a basis for large-scale deployment of nuclear power at a global level.
There is a need, in addition to evolutionary systems, to develop innovative designs with much shorter construction times and with significantly lower specific capital costs. These designs should be attractive to the deregulated markets in western industrialised countries when the time comes to replace existing reactors. The new designs should also be attractive to developing countries with small electricity grids, or in regions without grid connections, or for non-electricity applications such as district heating and desalination. Whether it should be the same type of reactor and fuel cycle system for both industrialised and developing countries has not yet been resolved.
The Intenational Nuclear Safety Advisory Group (INSAG) suggested requiring that future nuclear plants be safer by a factor of 10 than the targets set for existing reactors (ie target of 10-5/year for core damage and 10-6/year for large radioactive releases for future plants).
The INSAG-12 report states: "Another objective for these future plants is the practical elimination of accident sequences that could lead to a large early radioactive release, whereas severe accidents that could imply late containment failure would be considered in the design process with realistic assumptions and best estimate analysis so that the consequences would necessitate only protective measures limited in area and time."
Evolutionary designs explore avenues to increase safety which include using modern control technology, simplifying safety systems, making use of passive designs and extending the required response times for safety systems actuation and operator action. A primary goal could be a level of confidence in plant safety sufficient to eliminate the need for detailed evacuation plans, emergency equipment, and periodic emergency evacuation drills.
However, in spite of the evolutionary improvements in safety, support for nuclear power has not increased in western Europe and North America. There are different explanations for this, but one strong reason is that, given there have been significant accomplishments in the area of safety, other issues such as economics, spent fuel and nuclear waste management, have replaced improvement of existing safety features as the greatest challenge to the future development of the nuclear industry.
The situation is different in developing countries where most new reactors are likely to be built. These countries are more likely to profit from the enhanced and passive safety features of the new generation of reactors with a stronger focus on effective use of intrinsic characteristics, simplified plant design, easy construction, operation and maintenance.
Spent fuel and waste management
Although the volumes of nuclear waste are small compared to those from other forms of electricity generation, spent fuel and radioactive wastes from nuclear power plants and spent fuel reprocessing – and ultimately from plant decommissioning – still need to be managed safely.
Spent fuel can be safely stored for long periods in water-filled pools or dry facilities, some of which have been in operation for 30 years. Shortage of capacity for spent fuel storage is today's eminent issue in several countries where long-term waste disposal policy remains unsettled. Scientists generally agree that geological disposal of spent fuel or high-level radioactive waste from reprocessing can be carried out safely in stable geological formations. However, site selection is a major political issue in most countries developing such facilities, and no such commercial facility has yet been authorised. Currently, most high-level waste from commercial nuclear power is either stored on-site or transported to interim storage sites.
The absence of demonstration of a permanent waste disposal facility has exacerbated political concerns, particularly in western countries and countries with small territories. This has introduced uncertainties regarding future operation, political willingness and financial viability. Licensing and opening of disposal facilities in the countries currently engaged in studies of deep geological disposal would provide a convincing demonstration that it can be done.
It is thought that the development of innovative concepts for nuclear fuel cycles aimed at reducing nuclear waste volume and toxicity, and enhancing safety and cost-effectiveness of thefuel cycle, might mitigate political concerns in this area.
Countries with small nuclear programmes, or with a fragile economy, generally lack the resources to develop any type of back-end fuel cycle services, including geological repositories. New approaches must be analysed, such as development of multinational back-end fuel cycle centres. The IAEA is examining factors that would need to be addressed for this issue.
Adequate protective measures are essential to prevent proliferation of nuclear material.
A large global increase in the number of nuclear plants and the consequent increase in the amount of spent fuel containing plutonium are concerns, but the spread of critical uranium enrichment and plutonium extraction technologies would be an even greater concern.
Innovations in reactor designs and fuel cycle arrangements are being pursued to allow substantial expansion of nuclear power, including in developing countries, while minimising access to nuclear materials for use in weapons, and the technologies allowing their production.
An assured, economically accessible and environmentally benign fuel supply should contribute to large-scale nuclear energy development. Naturally occurring uranium is a finite resource. Presently known uranium reserves are sufficient to fuel the world's existing reactors for the first half of the 21st century. Thorium is another fuel candidate for nuclear power. High enriched uranium and plutonium from dismantled weapons programmes will also add to nuclear resources.
There is no major difficulty in doubling or tripling world nuclear capacity. Higher demand would raise prices and stimulate exploration and expand the resource base.
Existing and advanced reactors currently utilise only about 1% of the energy content of the fuel. Spent fuel reprocessing and recycling of extracted fissile uranium and plutonium in thermal reactors, as several countries already practice, may extend fuel availability by 40%. There are a number of efforts underway to improve the energy utilisation rate of a nuclear fuel cycle, even for existing plants. Moreover, there has been a consensus in the nuclear community that development of breeder reactors and plutonium recycling would effectively decouple nuclear power from resource considerations for large-scale development, although there are different opinions about their economic and non-proliferation features.
Status of innovative R&D
Technological development is taking place in three general categories:
•Currently operating commercial facilities – improvements in maintenance, operations, engineering support, fuel supply, etc.
•Evolutionary designs – improvements in design and operation for near-term future deployment, involving moderate changes from currently operating commercial facilities.
•Innovative designs – advances in design and operation involving major departures from currently operating commercial facilities for long-term future deployment.
The first two categories of development are critical, particularly for the next two decades, in order to keep nuclear power alive while more dramatic innovations are being prepared. This bridging effort based on existing evolutionary designs is crucial, and will define the future of nuclear power in the first instance. The subsequent generation of reactors and fuel cycle that must form the basis for large-scale expansion of nuclear power worldwide must depend on innovations in nuclear technology.
The need for innovative R&D has been recognised by the nuclear industry and by those countries that believe in the overall benefits, viability and importance of nuclear power for the long term. Currently, R&D on innovative nuclear fuel cycle and reactor concepts is being performed in Argentina, Canada, China, France, India, Japan, Korea, Russia, South Africa and the USA. The USA embarked on a Nuclear Energy Research Initiative in 1999 to develop advanced reactor and fuel cycle concepts and scientific breakthroughs in nuclear technology to overcome obstacles to the expanded use of nuclear energy.
As an example, attention in some of the above countries has focused on development of small reactors which have various combinations of relative simplicity of design, economy of mass production, and reduced siting costs. The table shows some examples of small reactors under development. The table is not complete. There are many other designs, most of them still at the conceptual level.
There are differences of opinion about the commercial potential of small reactors. Some consider that the main objective of the development of small reactors is to increase the potential use of nuclear energy for electricity production or desalination in remote areas where fossil fuel costs are high. These parties assume that small reactors will not be able to compete with large-scale evolutionary reactors, that they will complement then in additional areas where large-scale reactors are not suitable for use. Examples of these types of small reactor designs are KLT-40 and SMART.
Others believe that a breakthrough is possible in the cost of baseload electricity from small reactors, and that they will compete with large-scale nuclear plants and even gas-fired generation. These parties cite as examples the PBMR and the Carem-25. On-site construction with factory built structures and components, including complete modular units for fast installation, are some of the intended features of these reactors. It is also expected that these will be easier to finance and be suitable for deployment even in regions with modest electricity grids.
From early in the development of nuclear power in the 1960s, the closed fuel cycle scheme with breeder reactor was perceived as the best option for large-scale nuclear energy deployment. However, technological breakthroughs over a range of reactors and a range of reactor characteristics are now needed to cope with emerging issues such as non-proliferation, environmental mitigation, economics, and enhanced safety and security needs. Many countries with nuclear power programmes have dealt with these issues at least at the technical level, and have moreover set out new programmes for innovative nuclear fuel cycles.
Desireable features of innovative fuel cycles are:
•Reduction of nuclear waste and the hazards associated with its long-term storage;
•Furtherance of non-proliferation aims, namely that nuclear materials cannot be easily acquired or readily converted for non-peaceful purposes;
•Improved efficiency in resource use.
Examples of recent work in innovative fuel cycles are given in the table. Although no large-scale programmes on innovative fuel cycles are currently being implemented, some countries are investigating the necessary steps to change the current situation.
The IAEA's on-going activities on innovative reactor and fuel cycle technologies include the activities of several international working groups and coordinated research projects. Furthering international cooperation has always been understood to constitute one of the main areas of activities where the IAEA can be of benefit to its members.
National activities on innovative reactor and fuel cycle systems, and the desireability of coordinating them internationally, have been acknowledged at several meetings held under the auspices of the IAEA. The IAEA Scientific Forum, the Advisory Group Meeting on "Development of a Strategic Plan for an International Research and Development Project on Nuclear Fuel Cycles and Power Plants", and the Industry Forum are recent examples. These meetings have recommended that the IAEA take steps to facilitate assessment of the potential for, and exchange of information on, innovative reactors and fuel cycles.
Taking this into account, the IAEA is establishing a task force on innovative reactors and fuel cycles. To finalise the scope and objectives of the proposed task force, and to define the human and financial resources necessary to sustain it, the IAEA convened a meeting of senior officials in November 2000.
The task force will proceed on two tracks:
•The first track will involve a global assessment of the users’ requirements for future reactors and fuel cycles in order to have a better understanding of the demand and potential for the application of innovative reactors and fuel cycles.
•The second track will involve a compilation and review of technical features and characteristics of innovative reactor and fuel cycles that could meet projected requirements and demand.
The task force may also make recommendations about follow-up actions that the IAEA and member states may consider, including ways to facilitate information exchange and cooperative research and development among countries working on similar design concepts, to stimulate the pooling of resources and expertise.