The Future of Nuclear Power

China is planning to increase the number of its nuclear reactors in the near future. Finland and France have recently decided to build the first European pressurized reactor (EPR) designed by French-German collaboration. A significant extension of the life of existing reactors, between 10 to 20 years, is now likely. The German government may wish to reconsider this year its decision to begin shutting down its nuclear power plants. The possible German decision would be a first step to extending the life of the existing nuclear power plants. Thus, if the present trend continues, the number of nuclear reactors in the world should increase.

The development of nuclear power would follow a two-step process:

• The first step would be to progressively replace the old reactors between now and 2040 with reactors of the third generation. These reactors are essentially ready to be built. Safety and their overall performance have been significantly increased. They are designed to last 60 years.

• In a second step, starting around 2040, reactors of the fourth generation using new advanced technologies would be built. The goal of their design is to be more competitive from an economic point of view, to be much safer and burn a significant part of their waste. The fuel cycle should be designed to avoid the possibility of nuclear proliferation. These reactors are at the R&D stage.

Years

Fig. 1. A possible scenario for the installation of future nuclear reactors in France proposed by the EDF company. In this scenario, the EPR generation replaces the present generation, and reactors of the future generation, "Generation IV" appear around 2040

Years

Fig. 1. A possible scenario for the installation of future nuclear reactors in France proposed by the EDF company. In this scenario, the EPR generation replaces the present generation, and reactors of the future generation, "Generation IV" appear around 2040

Between 2020 and 2040, advanced new reactors of the third generation will begin to take over the power plants of the present generation. Construction of the first EPR (European pressurized water reactor) in France will start in 2007. This reactor will produce its first electricity in 2012. It is an example of advanced design of the pressurized water technology of the "third generation." It is designed to provide electricity more efficiently and more safely than the existing nuclear reactors. It will generate 1,600 megawatts of electricity — compared to 900 for most current reactors — need less regular recharging and should have a life span of 60 years. The reactor is designed to reduce the risk of accident by a factor of 10 and its double casing should withstand the impact of an aircraft. In the event of a disaster, the reactor core is designed to avoid the type of accident that occurred in Chernobyl.

The reactors of the third generation are advanced designs of the existing reactors, ready to replace the existing generation. Preparation for the future sustainable development of nuclear energy will involve a new generation of nuclear power generation systems, in an inclusive approach covering all the aspects of the reactor and fuel cycle. Today, overall, only 4% of the initial quantity of fuel is consumed in a reactor, i.e., less than 1% of the quantity of natural uranium needed for the production of enriched uranium. The spent fuel removed from the reactors contains 95% uranium, 1% plutonium and 4% fission products. Only fission products constitute waste. Uranium and plutonium can be reused to produce energy. With the dual aim of economizing natural resources and optimizing waste management, some countries, such as France, process the spent fuel to separate the energy-yielding materials from the waste. The recycled uranium is stored with the prospect of its use at a later date in fast breeder reactors, and the plutonium is recycled in today's reactors in the form of MOX fuel, a mix of uranium and plutonium. If the use of nuclear energy is to be greatly expanded to reduce man-made greenhouse gases, some such system will be needed.

To continue the development of nuclear energy, we must provide effective and acceptable technical solutions for the long-term management of the radioactive wastes produced by current reactors; solutions do exist and could be gradually implemented [7]. The concept of deep geologic disposal of high-level wastes has been studied extensively in many national and international research programs for several decades. Considerable technical progress has been made over this period. Although practical experience in building and operating geologic repositories for high-level waste is still mainly limited to a few pilot-scale facilities, there is today a high level of confidence within the scientific and technical community that the geologic repository approach is capable of safely isolating the waste from the bios phere for as long as it poses significant risks. This view has been stated and supported in several recent national and international assessments [913]. These conclusions are discussed in ref. [2]. They are based on:

• An understanding of the processes and events that could transport radio nuclides from the repository to the biosphere;

• Mathematical models that enable the long-term environmental impact of repositories to be quantified; and

• Natural analog studies that support the models and their extrapolation to the very long time scales required for waste isolation. Natural analogs also provide evidence that key processes important to modeling the performance of geologic systems over long time periods have not been overlooked [10].

A geologic repository must provide protection against every plausible scenario in which radionuclides might reach the biosphere and expose the human population to dangerous doses of radiation. Various possibilities must

Fig. 2 Comparison of three fuel cycles. On the left side is the once-through cycle in which only 1% of the natural uranium is used. The process used in Europe and Japan where plutonium is recycled once is shown in the middle of the figure. The right side of the figure schematically describes an advanced multi-recycling system. Actinides and plutonium are first separated from fission products and then reprocessed. An accelerator-driven system would be the final step to burn the remaining waste

Fig. 2 Comparison of three fuel cycles. On the left side is the once-through cycle in which only 1% of the natural uranium is used. The process used in Europe and Japan where plutonium is recycled once is shown in the middle of the figure. The right side of the figure schematically describes an advanced multi-recycling system. Actinides and plutonium are first separated from fission products and then reprocessed. An accelerator-driven system would be the final step to burn the remaining waste be considered, including the risk of volcanic activity and the possibility of human intrusion into the repository, either inadvertent or intentional. Of the possible pathways to the biosphere, those receiving most attention involve the entry of groundwater into the repository, the corrosion of the waste containers, the leaching of radio nuclides into the groundwater and the migration of the contaminated groundwater towards locations where it might be used as drinking water or for agricultural purposes. Although the details vary among national programs, the basic approach to repository design in every case is based on a multi-barrier containment strategy, combining a suitable geologic, hydrologic and geochemical environment with an engineered barrier system that takes advantage of the main features of that environment. A well-chosen geologic environment will support and enhance the functioning of the engineered barrier system, while protecting it from large perturbations such as tectonic activity or fluctuations in groundwater chemistry due to glaciations or other climate changes [9].

Studies are underway on multiple recycling of plutonium in power reactors, thus destroying it and leaving the fission fragments and minor acti-nides for geological storage. Also under study are transmutation systems that convert the long-lived component of spent fuel to a form only requiring isolation for hundreds to a thousand years — a time span of already existing man-made structures.

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