In the past, the leading countries were looking for fundamentally new solutions in the field of engines for rocket and space technology. The most daring proposals concerned the creation of the so-called. nuclear rocket engines based on a fissile material reactor. In our country, work in this direction gave real results in the form of an experimental RD0410 engine. Nevertheless, this product did not manage to find its place in promising projects and to influence the development of domestic and world astronautics.
Proposals and projects
Already in the fifties, a few years before the launch of the first satellite and a manned spacecraft, the prospects for the development of rocket engines on chemical fuel were determined. The latter made it possible to obtain very high characteristics, but the growth of the parameters could not be infinite. In the future, the engines had to "hit the ceiling" of their capabilities. In this regard, for the further development of rocket and space systems, fundamentally new solutions were required.
Built, but not tested by RD0410 NRM
In 1955, academician M. V. Keldysh came up with an initiative to create a rocket engine of a special design, in which a nuclear reactor would act as a source of energy. The development of this idea was entrusted to NII-1 of the Ministry of Aviation Industry; V. M. Ievlev. In the shortest possible time, the specialists worked out the main issues and proposed two options for a promising NRE with the best characteristics.
The first version of the engine, designated as "Scheme A", proposed the use of a reactor with a solid-phase core and solid heat exchange surfaces. The second option, "Scheme B", envisaged the use of a reactor with a gas-phase active zone - the fissile substance had to be in a plasma state, and thermal energy was transferred to the working fluid by means of radiation. Experts compared the two schemes and considered option "A" more successful. In the future, it was he who was most actively worked out and even reached full-fledged tests.
In parallel with the search for the optimal designs of the NRE, the issues of creating a scientific, production and testing base were being worked out. So, in 1957 V. M. Ievlev proposed a new concept for testing and fine-tuning. All the main structural elements had to be tested at different stands, and only after that they could be assembled into a single structure. In the case of "Scheme A", this approach implied the creation of full-scale reactors for testing.
In 1958, a detailed resolution of the Council of Ministers appeared, which determined the course of further work. M. V. Keldysh, I. V. Kurchatov and S. P. Korolyov. At NII-1, a special department was formed, headed by V. M. Ievlev, who was to deal with a new direction. Also, several dozen scientific and design organizations were involved in the work. The participation of the Ministry of Defense was planned. The work schedule and other nuances of the extensive program were determined.
Subsequently, all project participants actively interacted in one way or another. In addition, in the sixties, conferences were held twice, devoted exclusively to the topic of NRM and related issues.
Test base
As part of the NRE development program, it was proposed to apply a new approach to testing and testing the necessary units. At the same time, the specialists faced a serious problem. The verification of some products was supposed to be carried out in a nuclear reactor, but carrying out such activities was extremely difficult or even impossible. Testing could be hampered by economic, organizational or environmental difficulties.
Fuel assembly diagram for IR-100
In this regard, new methods of testing products were developed without the use of nuclear reactors. Such checks were divided into three stages. The first involved the study of processes in the reactor on models. Then the components of the reactor or engine had to pass mechanical and hydraulic "cold" tests. Only then did the assemblies have to be checked under high temperature conditions. Separately, having worked out all the components of the NRE at the stands, it was possible to start assembling a full-fledged experimental reactor or engine.
To carry out three-stage tests of units, several enterprises have developed and built various stands. Technique for high-temperature testing is of particular interest. During its development, it was necessary to create new technologies for heating gases. From 1959 to 1972, NII-1 developed a number of high-power plasmatrons that heated gases up to 3000 ° K and made it possible to carry out high-temperature tests.
Especially for the development of "Scheme B" it was necessary to develop even more complex devices. For such tasks, a plasmatron with an output pressure of hundreds of atmospheres and a temperature of 10-15 thousand degrees K was required. By the end of the sixties, a technology for heating a gas based on its interaction with electron beams appeared, which made it possible to obtain the required characteristics.
The resolution of the Council of Ministers provided for the construction of a new facility at the Semipalatinsk test site. There it was necessary to build a test bench and an experimental reactor for further testing of fuel assemblies and other components of the NRE. All the main structures were built by 1961, and at the same time the first start-up of the reactor took place. Then the polygon equipment was refined and improved several times. Several underground bunkers with the necessary protection were intended to accommodate the reactor and personnel.
In fact, the project of a promising nuclear rocket engine was one of the most daring undertakings of its time, and therefore led to the development and construction of a mass of unique devices and test instruments. All these stands made it possible to carry out a lot of experiments and collect a large amount of data of various kinds, suitable for the development of various projects.
Scheme A
Back in the late fifties, the most successful and promising version of the engine type "A". This concept proposed the construction of a nuclear rocket engine based on a reactor with heat exchangers responsible for heating the gaseous working fluid. The ejection of the latter through the nozzle was supposed to create the required thrust. Despite the simplicity of the concept, the implementation of such ideas was associated with a number of difficulties.
FA model for IR-100 reactor
First of all, the problem of choosing materials for the construction of the core arose. The design of the reactor had to withstand high thermal loads and maintain the required strength. In addition, it had to pass thermal neutrons, but at the same time not lose characteristics due to ionizing radiation. Uneven heat generation in the core was also expected, which placed new demands on its design.
To search for solutions and refine the design, a special workshop was organized at NII-1, which was to make model fuel assemblies and other core components. At this stage of the work, various metals and alloys, as well as other materials, were tested. For the manufacture of fuel assemblies, tungsten, molybdenum, graphite, high-temperature carbides, etc. could be used. Also, a search was carried out for protective coatings to prevent the destruction of the structure.
In the course of the experiments, the optimal materials for the manufacture of individual components of the NRE were found. In addition, it was possible to confirm the fundamental possibility of obtaining a specific impulse of the order of 850-900 s. This gave the promising engine the highest performance and a significant advantage over chemical fuel systems.
The reactor core was a cylinder about 1 m long and 50 mm in diameter. At the same time, it was envisaged to create 26 variants of fuel assemblies with certain features. Based on the results of subsequent tests, the most successful and effective ones were selected. The found design of fuel assemblies provided for the use of two fuel compositions. The first was a mixture of uranium-235 (90%) with niobium or zirconium carbide. This mixture was molded in the form of a four-beam twisted rod 100 mm long and 2.2 mm in diameter. The second composition consisted of uranium and graphite; it was made in the form of hexagonal prisms 100-200 mm long with a 1-mm inner channel that had a lining. The rods and prisms were placed in a sealed heat-resistant metal case.
Tests of assemblies and elements at the Semipalatinsk test site began in 1962. For two years of work, 41 reactor start-ups took place. First of all, we managed to find the most effective version of the core content. All major solutions and characteristics were also confirmed. In particular, all units of the reactor coped with thermal and radiation loads. Thus, it was found that the developed reactor is capable of solving its main task - to heat gaseous hydrogen to 3000-3100 ° K at a given flow rate. All this made it possible to start developing a full-fledged nuclear rocket engine.
11B91 at "Baikal"
In the early sixties, work began on the creation of a full-fledged NRE based on existing products and developments. First of all, NII-1 studied the possibility of creating a whole family of rocket engines with different parameters, suitable for use in various rocketry projects. From this family, they were the first to design and build a low-thrust engine - 36 kN. Such a product could later be used in a promising upper stage, suitable for sending spacecraft to other celestial bodies.
IRGIT reactor during assembly
In 1966, NII-1 and the Chemical Automatics Design Bureau began joint work to shape and design the future nuclear rocket engine. Soon the engine received indexes 11B91 and RD0410. Its main element was a reactor named IR-100. Later, the reactor was named IRGIT ("Research reactor for group studies of TVEL"). Initially, it was planned to create two different nuclear projectors. The first was an experimental product for testing at the test site, and the second was a flight model. However, in 1970, the two projects were combined with a view to conducting field tests. After that, KBHA became the leading developer of the new system.
Using the developments in preliminary research in the field of nuclear propulsion, as well as using the existing test base, it was possible to quickly determine the appearance of the future 11B91 and begin a full-fledged technical design.
At the same time, the "Baikal" bench complex was created for future tests at the test site. The new engine was proposed to be tested in an underground facility with a full range of protection. Means for collecting and settling the gaseous working fluid were provided. In order to avoid emission of radiation, the gas had to be kept in gasholders, and only after that it could be released into the atmosphere. Due to the particular complexity of the work, the Baikal complex has been under construction for about 15 years. The last of its objects were completed after the start of tests on the first.
In 1977, at the Baikal complex, a second workstation for experimental installations was commissioned, equipped with a means of supplying a working fluid in the form of hydrogen. On September 17, the physical launch of the 11B91 product was performed. Power start-up took place on March 27, 1978. On July 3 and August 11, two fire tests were carried out with the full operation of the product as a nuclear reactor. In these tests, the reactor was gradually brought to power of 24, 33 and 42 MW. The hydrogen was heated to 2630 ° K. In the early eighties, two other prototypes were tested. They showed power up to 62-63 MW and heated gas up to 2500 ° K.
RD0410 project
At the turn of the seventies and eighties, it was a question of creating a full-fledged NRM, fully suitable for installation on missiles or upper stages. The final appearance of such a product was formed, and tests at the Semipalatinsk test site confirmed all the main design characteristics.
The finished RD0410 engine was noticeably different from existing products. It was distinguished by the composition of the units, the layout and even the appearance, due to other principles of operation. In fact, RD0410 was divided into several main units: a reactor, means for supplying a working fluid and a heat exchanger and a nozzle. The compact reactor occupied a central position, and the rest of the devices were placed next to it. Also, the YARD needed a separate tank for liquid hydrogen.
The total height of the RD0410 / 11B91 product reached 3.5 m, the maximum diameter was 1.6 m. The weight, taking into account radiation protection, was 2 tons. The calculated thrust of the engine in the void reached 35.2 kN or 3.59 tf. The specific impulse in the void is 910 kgf • s / kg or 8927 m / s. The engine could be turned on 10 times. Resource - 1 hour. By means of certain modifications in the future, it was possible to increase the characteristics to the required level.
It is known that the heated working fluid of such a nuclear reactor had limited radioactivity. Nevertheless, after the tests, it was defended, and the area where the stand was located had to be closed for a day. The use of such an engine in the Earth's atmosphere was considered unsafe. At the same time, it could be used as part of the upper stages that begin work outside the atmosphere. After use, such blocks should be sent to the disposal orbit.
Back in the sixties, the idea of creating a power plant based on a nuclear reactor appeared. The heated working fluid could be fed to a turbine connected to a generator. Such power plants were of interest for the further development of astronautics, since they made it possible to get rid of the existing problems and restrictions in the field of generating electricity for onboard equipment.
In the eighties, the idea of a power plant reached the design stage. A project of such a product based on the RD0410 engine was being worked out. One of the experimental reactors IR-100 / IRGIT was involved in experiments on this topic, during which it provided the operation of a 200 kW generator.
New environment
The main theoretical and practical work on the subject of the Soviet NRE with a solid-phase core was completed by the mid-eighties. The industry could start developing a booster block or other rocket and space technology for the existing RD0410 engine. However, such works were never started on time, and soon their start became impossible.
At this time, the space industry did not have enough resources for the timely implementation of all plans and ideas. In addition, the notorious Perestroika soon began, which put an end to the mass of proposals and developments. The reputation of nuclear technology was severely affected by the Chernobyl accident. Finally, there were political problems during that period. In 1988, all work on the YARD 11B91 / RD0410 was stopped.
According to various sources, at least until the beginning of the 2000s, some objects of the Baikal complex still remained at the Semipalatinsk test site. Moreover, on one of the so-called. the experimental reactor was still located in the workplace. KBKhA managed to manufacture a full-fledged RD0410 engine, suitable for installation on a future upper stage. However, the technique for using it remained in the plans.
After RD0410
The developments on the subject of nuclear rocket engines have found application in a new project. In 1992, a number of Russian enterprises jointly developed a two-mode engine with a solid-phase core and a working fluid in the form of hydrogen. In the rocket engine mode, such a product should develop a thrust of 70 kN with a specific impulse of 920 s, and the power mode provides 25 kW of electrical power. Such a NRE was proposed for use in interplanetary spacecraft projects.
Unfortunately, at that time the situation was not conducive to the creation of new and bold rocket and space technology, and therefore the second version of the nuclear rocket engine remained on paper. As far as is known, domestic enterprises still show a certain interest in the subject of NRE, but the implementation of such projects is not yet possible or expedient. Nevertheless, it should be noted that within the framework of previous projects, Soviet and Russian scientists and engineers were able to accumulate a significant amount of information and gain important experience. This means that when a need arises and a corresponding order appears in our country, a new NRE can be created similar to the one tested in the past.
