The status of development of small and medium sized reactors

Several IAEA Member States have shown their interest in reactor designs, having a smaller power rating [100–500 MW(e) range] than those generally available on the international market. These small and medium sized power reactors are of interest either for domestic applications or for export into countries with less developed infrastructure. There are different developments undertaken for these power reactors to be ready for offering in the nineties and beyond.The paper gives an overview about the status and different trends in IAEA Member States in the development of small and medium sized reactors for the 90's and provides an outlook for very new reactor designs as a long term option for nuclear power.     

Nuclear fuel considerations for the 21 century

There are many external influences that may control the path that nuclear power deployment follows. In the next 50 years several events may unfold. Fear of the consequences of the greenhouse effect may produce a carbon tax that would make nuclear power economically superior very quickly. This, in turn, would increase the rate at which uranium reserves diminish due to the increased rate of nuclear power deployment. However, breakthroughs in the extraction of uranium from the sea or deployment of fast breeder reactors would greatly extend the uranium reserves and, as well, utilize the thorium cycle.On the other hand, carbon sequestering technology breakthroughs could keep fossil fuels dominant for the remainder of the century. Nuclear power may only then continue, as today, in a lesser role or even diminish. Fusion power or new developments in solar power could completely displace nuclear power as we know it today.Even more difficult to predict is when the demand for mobile fuel for transportation will develop such that hydrogen and hydrogen rich fuel cells will be in common use. When this happens, nuclear power may be the energy source of choice to produce this fuel from water or methane. In a similar vein, the demand for potable and irrigation water may be another driver for the advent of increased deployment of nuclear power.With all these possibilities of events that could happen it appears impossible to predict with any certainty which path nuclear power deployment may take. However, it is necessary to define a strategy that is flexible enough to insure that when a technology is needed, it is ready to be deployed.For the next few decades there will be an evolutionary improvement in the performance of uranium oxide and mixed uranium oxide-plutonium oxide (MOX) LWR fuels. These improvements will be market driven to keep the cost of fuel and the resulting cost of nuclear power electricity as competitive as possible. The development of fuels for accelerator transmutation and for reactor transmutation with inert matrix fuels is in its infancy. A great deal of research has been initiated in a number of countries, which has been summarized in recent conferences. In Europe the work on these fuels is directed at the same problem as their utilization of MOX; namely to reduce the inventory of separated plutonium, minor actinides, and Long Lived Fission Products (LLFP). In the United States there is no reprocessing and thus no inventory of separated civilian plutonium. However, in the United States there is a resistance to a permanent spent fuel repository and thus accelerator transmutation presents a possible alternative. If nuclear power does have a long-term future, then the introduction of the fast reactor is inevitable. Included in the mission of the fast reactors would be the elimination of the inventory of separated plutonium while generating useful energy. The work that is ongoing now on the development of fuel concepts for assemblies that contain actinides and LLFP would be useful for fast reactor transmutation.There is still a great deal of work required to bring the fast breeder reactor option to maturity. Fortunately there is perhaps a fifty-year period to accomplish this work before fast breeders are necessary. With regard to fast reactor fuel development, future work should be considered in three stages. First, all the information obtained over the past forty years of fast reactor fuel development should be completely documented in a manner that future generations can readily retrieve and utilize the information. Fast reactor development came to such an abrupt halt world-wide that a great deal of information is in danger of being lost because most of the researchers and facilities are rapidly disappearing. Secondly, for all of the existing fast reactor fuels, and this includes, oxides, carbides, nitrides, and metallic fuels, the evolutionary work was far from being completed. Although mixed oxide fuels were probably the furthest advanced, there were many concepts for improved claddings and advanced fabrication methods that were never fully explored. Finally, with such an extended period before fast reactors are needed there is ample time for truly innovative fuels to be developed that are capable of performing over a wide range of conditions and coolants.     

空间核反应堆电源用核燃料研制进展

核燃料是空间核反应堆电源的主要材料之一,由于空间核反应堆电源的运行条件明显有别于地面反应堆,空间核反应堆电源用核燃料的类型和技术要求也明显不同于地面反应堆。国际上空间核反应堆电源用核燃料研制取得了长足的进展,多种核燃料材料在工程应用中得到了检验,并在持续开发新型核燃料。我国在亚化学计量二氧化铀芯块、铀钼合金、铀氢锆合金、碳化铀芯块、氮化铀芯块等多种具备在空间堆中应用的燃料材料上开展了一定的研究,并掌握了部分材料性能数据。本文就上述内容展开论述,同时针对与国际相应领域明显落后的实际情况,提出了我国后续核燃料研究的初步设想。     

Non-technical Considerations in Regulation of Very Low Level Radioactive Waste: Comparative Analysis of Japan and the United States

With presently over 400 commercial nuclear power reactors being operated worldwide, many of which will retire within the next 50 years, the future generation of world nuclear energy depends upon strategies for low level waste management and decommissioning of those reactors. These strategies must address issues such as: economical feasibility, environmental and health standards, post-decommissioning land and facility usage. This paper considers those issues in the context of the inherently intertwined social and technical characteristics, with an emphasis on the management of very low level wastes. Until now 70 commercial power reactors have been decommissioned, however, most have been relatively small in comparison to those that will be preparing for decommissioning in the next 50 years. The resulting materials will add to the already increasing amounts of waste and material from nuclear reactors. Since the move to harmonization of clearance level regulation may have critical impacts on the environment and health as well as decommissioning costs and priority setting this paper examines both the areas of consensus and uncertainties between countries regarding very low level waste regulations for recycling of materials arising from decommissioning, against the background of international discussions. In conclusion, we discuss the need for deliberation regarding the assumptions and cultural factors.     

Current and Future Problems of the Fuel Supply for Nuclear Power

The structure of the nuclear fuel cycle, consisting of the technological stages of uranium production, refining, enrichment, fabrication of nuclear fuel, and reprocessing of the spent fuel for reuse of the fissioning materials, is examined. Supplying fuel includes supplying fuel for Russian nuclear power plants, propulsion and research reactors, export of fuel for nuclear power plants and research reactors constructed according to Russian designs, export of low-enriched uranium and fuel for nuclear power plants constructed according to foreign designs. The explored deposits of natural uranium, the estimated stores of uranium in reserve deposits, and warehoused stores will provide nuclear power with uranium up to 2030 and in more distant future with the planned rates of development. The transition of nuclear power plants to a new fuel run will save up to 20% of the natural uranium. The volume of reprocessing of spent fuel and reuse of ²³⁵U makes it possible to satisfy up to 30% of the demand for resources required for Russian nuclear power plants. The most efficient measure of the resource safety of Russian nuclear power is implementation of an interconnected strategy at each stage of the nuclear fuel cycle.     

福岛核事故后核电厂安全改进行动分析

介绍了福岛核事故后世界上主要核电国家相继开展的核电厂安全检查、再评价行动,并得出相应的检查和测试结论。法国、美国和中国等国家分别提出了福岛核事故后改进核电厂安全的建议、要求和行动,并制定了具体工程措施：在极端外部事件的设防,严重事故预防和缓解,水、电、通风实体改进,限制严重事故下的放射性释放和应急准备等主要方面开展的安全改进行动,将会提高核电厂的安全水平并提升缓解严重事故的能力。反思福岛核事故,总结福岛核事故对核电安全技术改进的促进作用,对未来核电安全技术的发展进行了展望。     

Tory II-C Nuclear Instrumentation System

The design of the nuclear instrumentation system for the Pluto series of nuclear ramjet test reactors is an attempt to provide a very flexible nuclear sensing system that will be adequate for Tory II-C and following test reactors. The nuclear detectors will be exposed to the leakage neutron flux from the reactor during operation. Since the leakage flux is proportional to reactor power, the neutron detectors will give a measure of reactor power. A difficulty in providing nuclear instruments for this reactor is the uncertainty in the neutron energy spectrum of the leakage flux at the detectors. Since detector response varies with neutron energy, a large margin of flexibility is desirable. A difficulty which may be encountered is a significant shift in neutron energy spectrum at high power and temperature. This would make indicated nuclear power nonlinear with calorimetric power. A difficulty in insufficient instrument overlap was encountered with the Tory II-A experiment where a large margin of flexibility would have been useful. The detector placement for the Tory II-A experiment had the power range detectors in line with the reactor and main air pipe. At high air flows there was a much greater mass of air between the detectors and the reactor, allowing fewer neutrons to reach the detectors per unit reactor power. This is the reason for the power range detectors being placed off to the side of the Tory II-C test vehicle. Not all difficulties can be foreseen, but provision is made where possible to overcome them.     

Nuclear Non-Proliferation Security on Exportation of Fast Reactors with a Closed Fuel Cycle

Atomic Energy - The exportation of fast reactors with a closed nuclear fuel cycle to countries that do not have nuclear weapons could commence within the next few decades, which will require...     

Nuclear power under the clean development mechanism

Not a few developing countries have been following a policy of positively introducing nuclear power to meet the predicted increase in energy demand in future, however, nuclear power development needs technically and financially advanced infrastructures. It is essential for the developing countries to receive technical and financial supports from a developed country or countries, in relation to procurement of funds, education/training of operation/maintenance personnel, assurance of safety, nuclear nonproliferation and safeguard etc., when they seek to introduce or develop nuclear power. It is expected that the developed countries would actively invest in the introduction or development of nuclear power plants in the developing countries, if the investing countries can get emission reduction credits through the Clean Development Mechanism (CDM) defined in the Article 12 of the Kyoto Protocol of the COP-3.

This paper examines effectiveness of the CDM, when it is used as an institutional means of funds raising and technical infrastructure development that are expected to be the greatest obstacles to introducing nuclear power in the developing countries, and proposes the guidelines which are specifically necessary to realize it. Funds that can be raised by Japan to a nuclear power project of developing country in return of the emission right of greenhouse gases were calculated, substituting coal-fired thermal power plants with nuclear power.     

Future Prospects for Growth of Nuclear Power in Russia

The need and unavoidability of further growth of nuclear power in the world and promising directions for growth of nuclear power in Russia are discussed. A characteristic feature for the next few decades will be further improvement of VVÉR reactors. Fast reactors will be required. The importance of building low-capacity nuclear power plants is pointed out and the basic technical-economic requirements which such plants must satisfy are formulated.     

HTR's role in process heat applications

Advanced high-temperature nuclear reactors create a number of new opportunities for nuclear process heat applications. These opportunities are based on the high-temperature heat available, smaller reactor sizes, and enhanced safety features that allow siting close to process plants. Major sources of value include the displacement of premium fuels and the elimination of CO₂ emissions from combustion of conventional fuels and their use to produce hydrogen. High value applications include steam production and cogeneration, steam methane reforming, and water splitting. Market entry by advanced high-temperature reactor technology is challenged by the evolution of nuclear licensing requirements in countries targeted for early applications, by the development of a customer base not familiar with nuclear technology and related issues, by convergence of oil industry and nuclear industry risk management, by development of public and government policy support, by resolution of nuclear waste and proliferation concerns, and by the development of new business entities and business models to support commercialization. New HTR designs may see a larger opportunity in process heat niche applications than in power given competition from larger advanced light water reactors. Technology development is required in many areas to enable these new applications, including the commercialization of new heat exchangers capable of operating at high temperatures and pressures, convective process reactors and suitable catalysts, water splitting system and component designs, and other process-side requirements. Key forces that will shape these markets include future fuel availability and pricing, implementation and monetization of CO₂ emission limits, and the formation of international energy and environmental policy that will support initiatives to provide the nuclear licensing frameworks and risk distribution needed to support private investment. This paper was developed based on a plenary session presentation at HTR-2006 which won Best Paper.     

日本小型核动力反应堆及其技术特点

日本原子能研究所研制了包括一体化船用堆(MRX)在内的几种小型核反应堆．MRX采用容器内置式控制棒驱动机构、水淹式安全壳、非能动余热排出系统;MR-100G和MR-1G是专门为区域供热和冷却系统提供能源,一回路系统自加压的全自然循环一体化压水堆．其排放物活性较低,小型化、模块式结构．可直接建于城市,甚至办公大楼的地下．,水下探测器用小型潜水反应堆(SCR)的设计思路与MRX基本相同．但一回路为全自然循环,日本小型核反应堆发展的技术思路清晰,注重用途的拓展,具有战略发展远见．在将我国大型核动力反应堆研制经验及其相应技术的推广方面,日本小型反应堆的发展思路值得借鉴。     

Actinide breeding and reactivity variation in a thermal spectrum ADSR – Part 2: Enhanced sustainability in the thermal spectrum

For more sustainable nuclear power to be realised improvements will be needed in the efficiency with which energy is derived from the remaining finite uranium reserves, while at the same time delivering reductions in the quantities of long-lived actinides contained within the spent fuel. The use of fast reactors to achieve this is the subject of renewed interest due to their beneficial capability to both burn and breed transuranic actinides. However, fast reactors have a mixed track record and have never been deployed in significant numbers despite considerable investment in the development of the technology over many years. In light of these difficulties, future advances in nuclear technology may be more readily realised through enhancements to the existing, well proven light water reactor (LWR) technology base.     

Sustainable futures using nuclear energy

We present the role of nuclear energy in a sustainable future. This addresses the social, economic and environmental concerns of us all. Nuclear energy today avoids the emission of nearly two billion tonnes of greenhouse gases (GHGs) each year, thanks to over 400 reactors operating worldwide.

Nevertheless, there is no real recognition of real incentives for large-scale non-emitters like nuclear energy and for emissions avoidance in current Kyoto and other policies. These approaches rely heavily on conservation, renewables and efficiency. These measures alone also will not significantly reduce the atmospheric greenhouse burden, because the world is still growing. Also, our (the world's) future economic growth (in all countries) is tied to energy and electricity use. Our prosperity, the alleviation of poverty and the sustainability of the world depend on having a supply of emissions-free and safe energy.

Recent price hikes in fossil fuels and power blackouts also emphasize our need for reliable, safe and cheap power, as is offered by nuclear energy when coupled with effective and secure waste disposal.

A particularly important role for nuclear power in the future will be its links to the hydrogen economy. It is now recognised that the introduction of hydrogen into the transportation sector will benefit the environment only when low carbon sources, such as nuclear reactors, are the primary energy source for hydrogen production. The future could well be the Hydrogen Age. We show that a major reduction in GHGs worldwide can be obtained by nuclear-electric production of hydrogen, thus alleviating their potential effects on future generations. We also demonstrate a potential key synergism with renewable wind power in the hybrid production of distributed hydrogen. Thus, nuclear energy supports and enables the World in its journey to a sustainable, safe and secure energy future.     

Market potential of small and medium-size nuclear reactors as combined heat and power plants in Europe

The preliminary results are presented concerning a study launched by the Commission of the European Communities to assess the potential market of small and medium-size nuclear reactors through EC Member countries. The study was aimed at identifying those factors that may have a role in shaping the eventual deployment and diffusion of this class of nuclear reactors. In a first phase, attention focused on modular high-temperature gas-cooled reactors that would be installed to produce low-temperature heat and power. Federal Republic of Germany, Italy and France are the countries for which the investigation has been completed. The time span of interest is up to the year 2020. Referring to this horizon, an appraisal has been made of the number of nuclear units which could come on line to cope with energy demand and their timing. Through the study a distinction is made between technical potential, economic potential, and effective market potential. It is understood indeed that both economic competitiveness towards other energy sources and also institutional or organizational factors may restrict the market which could become accessible and would be covered by the new nuclear plants.     

Nuclear power development in market conditions with use of multi-purpose modular fast reactors SVBR-75/100

This article presents an innovative nuclear power technology, based on the use of modular type fast-neutron reactors SVBR-75/100 having heavy liquid-metal coolant, i.e. eutectic lead–bismuth alloy, which was mastered in Russia for the nuclear submarines’ reactors. Reactor SVBR-75/100 possesses inherent self-protection and passive safety properties that allow excluding of many safety systems necessary for traditional type reactors. Use of this nuclear power technology makes it possible to eliminate conflicting requirements among safety needs and economic factors, which is particularly found in traditional reactors, to increase considerably the investment attractiveness of nuclear power based on the use of fast-neutron reactors for the near future, when the cost of natural uranium is low and to assure development of nuclear power in market conditions. On the basis of the factory-fabricated “standard” reactor modules, it is possible to construct the nuclear power plants with different power and purposes. Without changing the design, it is possible for reactor SVBR-75/100 to use different kinds of fuel and operate in different fuel cycles with meeting the safety requirements.     

Requirements for 21st centry nuclear power plants

The development of energy production in the 21st century will be subject to more uniform per capita and regional consumption. Among the competing sources of energy, the positive qualities of nuclear power-unlimited fuel resources, high energy intensiveness, and ecological compatibility with the possibility of the wastes being highly concentrated—predetermine the development of large-scale nuclear power. The conditions for the development of such nuclear power are its ecological effectiveness and safety (of the reactors and the fuel cycle with the production of wastes), nuclear fuel breeding with adequate characteristics, and guarantees of nonproliferation of fissioning materials. Continuity in the development of nuclear power dictates the requirements for reactor systems in the near and distant future. The acceptable level of safety is closely related to the scales of nuclear power and the applications of nuclear energy sources. However, progress in decreasing the potential danger of reactors and decreasing the cost of protective systems is unavoidable. In choosing new directions, it is important to demonstrate the new qualities in the solution of the problems facing nuclear power in the future. An adequate diversity of reactor technologies could exist in the future. The requirements that will face nuclear power plants in the future stages of development and the expected stages of this development are discussed. The jourmal variant of this report at the 10th annual conference of the Nuclear Society “From the first nuclear power plant in the world to power engineering of the twenty-first century” (June 28–July 2, 1999, Obninsk) Russian Science Center “Kurchatov Institute”. Translated from Atomnaya énergiya, Vol. 88, No. 1, pp. 3–14, January, 2000.     

Micro-structured nuclear fuel and novel nuclear reactor concepts for advanced power production

Many applications (e.g. terrestrial and space electric power production, naval, underwater and railroad propulsion and auxiliary power for isolated regions) require a compact-high-power electricity source. The development of such a reactor structure necessitates a deeper understanding of fission energy transport and materials behavior in radiation dominated structures. One solution to reduce the greenhouse-gas emissions and delay the catastrophic events' occurrences may be the development of massive nuclear power. The actual basic conceptions in nuclear reactors are at the base of the bottleneck in enhancements. The current nuclear reactors look like high security prisons applied to fission products. The micro-bead heterogeneous fuel mesh gives the fission products the possibility to acquire stable conditions outside the hot zones without spilling, in exchange for advantages – possibility of enhancing the nuclear technology for power production. There is a possibility to accommodate the materials and structures with the phenomenon of interest, the high temperature fission products free fuel with near perfect burning. This feature is important to the future of nuclear power development in order to avoid the nuclear fuel peak, and high price increase due to the immobilization of the fuel in the waste fuel nuclear reactor pools.     

Radiation Characteristics of Fuel and Wastes in the Uranium–Plutonium and Thorium–Uranium Fuel Cycle

The radiation characteristics of fuel cycles of various reactors – replacement candidates in the future nuclear power – are compared. Proceeding from the basic requirements (safety, fuel supply, and nonproliferation of fissioning materials), inherently safe fast reactors of the BREST type can be used as the basis for large-scale nuclear power. Thermal reactors, which can burn enriched uranium, thorium–uranium fuel, or mixed uranium–plutonium fuel with makeup with fissioning materials from fast reactors, will operate for a long time simultaneously with fast reactors in the future nuclear power. VVÉR-1000 and CANDU reactors are examined as representatives of thermal reactors; for each of these reactors the operation in various variants of the fuel cycle is simulated. It is shown that with respect to radiation characteristics of the fuel and wastes the thorium–uranium fuel cycle has no great advantages over the uranium–plutonium cycle.     

Preliminary Study on Future Society in Nuclear Quasi-Equilibrium

From the finiteness of the earth's natural resources, it is expected that our society will ultimately be in a nuclear quasi-equilibrium state, where each produced active nuclide density becomes constant.

In this paper some results from a preliminary study of the future society in nuclear quasi-equilibrium will be presented. The heavy nuclide densities and criticality were studied for four reference fission reactors, where actinoids are not discharged from the reactor but incinerated. They appeared to depend strongly on neutron spectrum in the reactor.