Space Nuclear Power in Views: 50 Years Ago and Prevision for 50 Years

Content Provider	Semantic Scholar
Author	Zrodnikov, Anatoly V. Zabudko, Alexey Linnik, Vladimir Alekseevich Dubinin, A. A. Ionkin, V. I. Yarygin, V. I.
Copyright Year	2013
Abstract	The results of scientific-technical and research-design works on the space nuclear power installations (SNPI) have been systemized. Brief description of the evolution of works on the SNPIs is presented. Characteristics of the installations, experience of developing and operating the installations have been analyzed. The presented analysis has also included the results obtained on development works and Projects that did not reach their technical realization but made it possible to develop scientific and technical potential of the space nuclear power for the investigations showing promise for the next 50 years. 1. Background: brief history of works on the SNPIs For about half a century the developed countries have been carrying out investigations into the area of using the nuclear power in the spacecraft. The purpose of these investigations is to design the highefficient autonomous and compact power sources based on nuclear reactor for electricity supplying the different vehicle-borne devices and/or for providing the spacecraft propulsion. The history reveals that the first applications of the nuclear power for the space systems relate to constructions of the nuclear rocket propulsions (NRP) in the USSR and USA. In the USSR in the space technique area the development works on large and medium nuclear space propulsions using homogeneous and heterogeneous types of reactors were carried out. The specific impulse of that propulsion can be 2-2,5 times as much as that of propulsions using chemical fuel. Since 1956 till 1965 a lot of the variants of the reactor designs had been considered and the optimal methods and ways of solving the problems of NRPs designing had been developed. The NRP parameters were first experimentally verified when the model fuel subassemblies (FSA) were tested in reactor IGR constructed in 1961. In 1966 the development works on the small heterogeneous reactors were launched for the purpose to construct the rocket with minimal dimensions. In the USSR the NRP works had been developed to the phase of the full-scale tests (IRGIT No 1, IRGIT No 2, IRGIT No 3). During 1961-1984 in compliance with the NRP Program ~ 10 nuclear reactors of various modifications (IGR, IVT, IRGIT and the like) were designed, fabricated and tested. In 1978-1984 they were tested [1] and the tests demonstrated sufficient operability of the reactor. In 1980s-1990s the development works on fast reactors for the power-propulsion installations in which the NRP mode was combined with electricity generating were launched. They demonstrated that there were potentials to get small values of propulsion for the space flights at considerable increase of reactors' specific (propulsion divided by weight) characteristics for that type NRP. The USA national Program on nuclear rockets ROVER/NERVA covered the years from 1955 to 1973. During that period over 40 nuclear reactors were tested, more than twenty reactors were subjected to the full-scale tests. The Program was recognized to be one of the most successful technical developments of the advanced technology [2]. The USSR development works adopted the scheme of the reactor with a heterogeneous core in which the neutron moderator material was located separately from fuel elements containing uranium. Fuel elements were surrounded by thermal insulation and encapsulated in the metallic case that formed a fuel elements assembly. Orientation toward the heterogeneous reactor and element-by-element development of its units was a fundamental distinction between the NSP construction Programs in the USSR and USA. As it was recognized later by the experts, among them the American specialists were also presented, this distinction was in favour of the Soviet Program [3]. In 1956 the works on studying feasibility to use the nuclear power installations (NPI) generating electricity at the spacecraft were launched. As the spacecraft's electricity supplying sources, the NPIs were considered as both the ones with machine conversion of thermal power into electricity and the ones with direct conversion of thermal power (thermoelectric and thermoemission ones) [1]. The NPI Projects with machine conversion were realized with different closed thermodynamic cycles. In the USSR the development works on NPIs with power machine conversion reached the phases of technical proposals and feasibility studies. Abroad, in the American and French Projects, the priority was given to NPIs based on power machine conversion (Brayton and Rankine cycles). For example, in the USA the NSPs with a reactor of the S8DR type and power conversion system with a Brayton cycle (30÷50 kWe) or with a Rankine cycle (power ranged from several hundred kW to several MW). Thermoelectric conversion in the radio-isotopic generators and in the NPIs (SNAP-10A, “BOUK”) was successfully used for electricity supplying the space stations. On August 14, 1964 the world's first nuclear installation “Romashka” with thermoelectric conversion of thermal power into electricity was put in operating. SNAP-10A was the USA first vehicle-borne electric plant with nuclear reactor that was tested in space in 1965 April. Its power was ~ 0,5 kW, it operated 43 days and was shut down soon due to the fault in the voltage regulator [4]. The similar NPI operated on Earth more than 10000 hours. In 1975-1988 domestic thermoelectric NPI “BOUK” of ~ 3 kWe was operating at the man-made Earth satellites of the “Cosmos” series. Development, designing and construction of those installations took ~ 10 years (SNAP-10A (1956-1965), “BOUK” (1961-1970)). By the year 1970 the basic R&D had been carried out, the first experimental installations had been fabricated, the ground-based delivery tests of NPI “BOUK” had been accomplished. The full-scale ground-based tests and flight-engineering development tests of the NPI had been carried out from 1970 till 1975 [1]. Altogether 33 launchings were made. The dates of their launchings, the entering and escaping orbits, the time of their flight functioning and the causes of its termination are cited in the Table in Paper [1]. Simultaneously (since 1971) the scientific and research works on finding the ways to increase the reactor power and the lifetime of installation “BOUK” were realized. With due account of experience of designing and constructing SNAP-10A, the USA scientists developed two variants of space power unit SNAP-8, namely with thermoelectric and machine conversion as well as the more powerful thermoelectric generators for usage in space NPIs (SP-100 and others). In the USSR the development works on constructing the thermoemission NPIs were launched in 1956-1958. They were stimulated by the USA publication that D. Grover (the USA) was going to test in reactor the diode which emitter would be heated from uranium carbide fission [1]. The total set of the expected characteristics made those power sources very promising for the spacecraft. Since the beginning of 1960s the scientific and research works on construction of the thermoemission NPIs with small (10÷100 kWe) and large power (200÷1000 kWe) reactors-converters have been intensively carried out with different class reactors. Detail description of designing and construction of NPI “TOPAZ” (~ 6 kW) with a slow neutrons reactor is cited in Papers [1, 5]. A physical note to the conceptual design of installation “TOPAZ” was issued in 1963 and seven years later (in 1970) the first NPI was launched and tested. Altogether, since 1970 till 1984 the ground-based power tests of the seven prototypes of thermoemission NPI “TOPAZ” were accomplished. These all enabled to begin to design the NPIs for carrying out the flight-engineering development tests on the testing area on the specially constructed technical position. Two experimental NPIs successfully passed the flight tests in 1987-1988 [1]. The great constructive contribution to designing NPIs “BOUK”, “TOPAZ” and other advanced installations was made by V.Ya. Poupko. Along with NPI “TOPAZ”, since the second half of the 1960s design works and ground-based development of thermoemission NPI “Yenisei” with a one-element electricity generating channel (EGC) were performed. The results obtained at constructing NPIs “BOUK”, “TOPAZ” and “Yenisei” enable validated consideration of the future NPI development on the basis of experience of “BOUK” and “TOPAZ” technologies [6]. In the USSR simultaneously with designing the “TOPAZ” type NPIs the research works on constructing the propulsion installations with reactor-converter (RC) of several hundred kW and several thousand kW were carried out. In the USA the thermoemission NPIs were designed for three ranges of electric power: ~10 kW, ~50 kW, ~150 kW (Programs SNAP and STAR). Further this principle of conversion was applied for NPI SP-100. The highest efforts in this area were purposed to development of thermoemission EGСs. The current USA Projects on space NPIs are based on concept HPS (Heatpipe Power System) using machine conversion systems [7]. In the USA Projects the powerful turbine-generators are used for advanced NPIs of the multi-mega-watt class. 2. Nuclear space propulsions One of the promising trends of the rocket technique is construction of the rocket with a nuclear propulsion.
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