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Recent assessments of the strategic prospects of the nuclear energy industry tend to show a somewhat condescending attitude towards fusion, which, regretfully, has grounds given the current state of affairs in nuclear science. However, the analysis of the problems and the potentialities of the fusion of light nuclei and fission of heavy nuclei suggests that a full-scale development of each of the two nuclear technologies inevitably involves the need to overcome some formidable technological, materials science, environmental, and economic problems, some of which may put the feasibility of pursuing these nuclear energy programs at question. At the same time, the physical features of the fission and fusion processes objectively suggest that it may be reasonable to combine the two nuclear technologies within a joint nuclear energy system to enable a greater synergetic effect. This apparently would markedly lessen the problems attendant upon the application of each of the discussed technologies in the course of the full-scale development of nuclear energy.

The strategic line of development of a nuclear power system based on fission and fusion reactors which ensures electricity generation on a specified scale, solves the fuel problem for a long-term outlook, and secures the lowest risk of environmental contamination is presented. A contemporary view of prospects of developing the nuclear power industry on the basis of replacement of thermal reactors in the future by fast reactors, owing to a long duration of this process and the necessity of additional resources of natural uranium, forces us to consider the possibility of implementation of this strategy as unlikely. In addition, the fuel cycle of fast reactors requires the quick reprocessing of the highly active spent fuel, and because of this, the fuel cycle will have a high risk of a negative radioactive effect on the environment. The transition of the nuclear power industry to fast reactors will lead to a full change of the infrastructure related to reactor construction and operation. In the development of a nuclear power system with fusion and fission reactors, the demands for natural uranium will correspond to current estimates of economically effective stockpiles, the risk of radioactive contamination of the environment associated with the spent fuel reprocessing will be the lowest, and the contemporary infrastructure of the nuclear power industry will be maintained, i.e., the prevalence of generating capacities based on thermal neutron reactors. Thus, the integration of nuclear power production by fusion and fission reactions into a unified system creates a significant synergetic effect, in which the deficiencies of each technology are compensated by another technology of nuclear power production.

A concept of a large-scale nuclear power engineering system equipped with fusion and fission reactors is presented. The reactors have a joint fuel cycle, which imposes the lowest risk of the radiation impact on the environment. The formation of such a system is considered within the framework of the evolution of the current nuclear power industry with the dominance of thermal reactors, gradual transition to the thorium fuel cycle, and integration into the system of the hybrid fusion-fission reactors for breeding nuclear fuel for fission reactors. Such evolution of the nuclear power engineering system will allow preservation of the existing structure with the dominance of thermal reactors, enable the reprocessing of the spent nuclear fuel (SNF) with low burnup, and prevent the dangerous accumulation of minor actinides. The proposed structure of the nuclear power engineering system minimizes the risk of radioactive contamination of the environment and the SNF reprocessing facilities, decreasing it by more than one order of magnitude in comparison with the proposed scheme of closing the uranium–plutonium fuel cycle based on the reprocessing of SNF with high burnup from fast reactors.

At present, 240 000 t of spent nuclear fuel (SF) has been accumulated in the world. Its long-term storage should meet safety conditions and requires noticeable finances, which grow every year. Obviously, this situation cannot exist for a long time; in the end, it will require a final decision. At present, several variants of solution of the problem of SF management are considered. Since most of the operating reactors and those under construction are thermal reactors, it is reasonable to assume that the structure of the nuclear power industry in the near and medium-term future will be unchanged, and it will be necessary to utilize plutonium in thermal reactors. In this study, different strategies of SF management are compared: open fuel cycle with long-term SF storage, closed fuel cycle with MOX fuel usage in thermal reactors and subsequent long-term storage of SF from MOX fuel, and closed fuel cycle in thermal reactors with heterogeneous fuel arrangement. The concept of heterogeneous fuel arrangement is considered in detail. While in the case of traditional fuel it is necessary to reprocess the whole amount of spent fuel, in the case of heterogeneous arrangement, it is possible to separate plutonium and 238U in different fuel rods. In this case, it is possible to achieve nearly complete burning of fissile isotopes of plutonium in fuel rods loaded with plutonium. These fuel rods with burned plutonium can be buried after cooling without reprocessing. They would contain just several percent of initially loaded plutonium, mainly even isotopes. Fuel rods with 238U alone should be reprocessed in the usual way.

The paper presents the results of the system research on the coordinated development of nuclear and fusion power engineering in the current century. Considering the increasing problems of resource procurement, including limited natural uranium resources, it seems reasonable to use fusion reactors as high-power neutron sources for production of nuclear fuel in a blanket. It is shown that the share of fusion sources in this structural configuration of the energy system can be relatively small. A fundamentally important aspect of this solution to the problem of closure of the fuel cycle is that recycling of highly active spent fuel can be abandoned. Radioactivity released during the recycling of the spent fuel from the hybrid reactor blanket is at least two orders of magnitude lower than during the production of the same number of fissile isotopes after the recycling of the spent fuel from a fast reactor.

Practical implementation of a closed nuclear fuel cycle implies solution of two main tasks. The first task is creation of environmentally acceptable operating conditions of the nuclear fuel cycle considering, first of all, high radioactivity of the involved materials. The second task is creation of effective and economically appropriate conditions of involving fertile isotopes in the fuel cycle. Creation of technologies for management of the high-level radioactivity of spent fuel reliable in terms of radiological protection seems to be the hardest problem.

Influence of the nuclear energy structure, the conditions of fuel burnup, and accumulation of new fissile isotopes from the raw isotopes on the main parameters of a closed fuel cycle is considered. The effects of the breeding ratio, the cooling time of the spent fuel in the external fuel cycle, and the separation of the breeding area and the fissile isotope burning area on the parameters of the fuel cycle are analyzed.

The results of systems studies of the coordinated development of nuclear and thermonuclear power generation to secure rapid growth of energy production in the current century are presented. Taking into consideration the increasing difficulties in meeting the required demand for energy, it is expedient to use thermonuclear reactors as high-power neutron sources for the production of nuclear fuel in a blanket. It is shown that in such a structural configuration of an energy system the fraction of thermonuclear sources can be relatively small. For sufficiently large scales of nuclear fuel production, even the paradigms for the development of nuclear power plants can change toward lower unit capacity in order to increase safety, simplify the fuel cycle, and do away with reprocessing of high-level spent fuel.

A concept is proposed for a fast reactor which has a potential for overcoming the safety and fuel-cycle related fears of large-scale development of nuclear power. This proposal is based on ideas advanced in 1958 at the Second Geneva Conference on World Use of Atomic Energy and is aimed at the implementation of the innovation potential of nuclear power for solving the most complex safety and fuel supply problems of reactor technology.

In the latest assessments of the strategic prospects for the development of nuclear energy, we can note the tendency of a condescendingly arrogant attitude towards thermonuclear fusion, which, unfortunately, largely corresponds to the real state of affairs. At the same time, an analysis of the problems and potential of two nuclear technologies based on reactions of fusion of light nuclei and fission of heavy ones shows the following. Independent large-scale development of each of these areas will inevitably lead to the need to overcome the still unresolved technological, material science, environmental and economic problems, some of which raise the question of the appropriateness of further development of these energy sectors. At the same time, the physical features of fission processes and fusion objectively indicate the expediency of combining them within the framework of a single nuclear energy system. Such a combination will provide a great synergistic effect, as a result of which the negative manifestations of the complex problems of each technology will significantly weaken on the path of large-scale development of the industry.