Nuclear rocket engines and nuclear rocket electric propulsion systems. Nuclear jet engines - the future of astronautics
Found an interesting article. In general, nuclear spacecraft have always interested me. This is the future of space exploration. Extensive work on this topic was also carried out in the USSR. The article is about them.
Atomic-powered space. Dreams and reality.
Doctor of Physical and Mathematical Sciences Yu. Ya. Stavissky
In 1950, I defended my degree in engineering physics at the Moscow Mechanical Institute (MMI) of the Ministry of Munitions. Five years earlier, in 1945, an engineering and physics department was formed there, which trained specialists for a new industry, whose tasks included mainly the production of nuclear weapons. The faculty was second to none. Along with fundamental physics in the scope of university courses (methods of mathematical physics, theory of relativity, quantum mechanics, electrodynamics, statistical physics, and others), we were taught a full range of engineering disciplines: chemistry, metal science, strength of materials, theory of mechanisms and machines, etc. Created by an outstanding Soviet physicist Alexander Ilyich Leipunsky, the Faculty of Engineering Physics of the MMI grew over time into the Moscow Engineering Physics Institute (MEPhI). Another Faculty of Engineering Physics, which also later merged into MEPhI, was formed at the Moscow Power Engineering Institute (MPEI), but if the main emphasis at MMI was on fundamental physics, then at the Energy Institute it was on thermal and electrophysics.
We studied quantum mechanics using the book by Dmitry Ivanovich Blokhintsev. Imagine my surprise when, during the distribution, I was sent to work with him. I am an avid experimenter (as a child I dismantled all the clocks in the house), and suddenly I get to a well-known theorist. I was seized with a slight panic, but upon arrival at the place - "Object B" of the USSR Ministry of Internal Affairs in Obninsk - I immediately realized that I was worried in vain.
By this time, the main topic of "Object B", which was actually headed by A.I. Leipunsky, has already formed. Here they created reactors with expanded reproduction of nuclear fuel - "fast breeders". As director, Blokhintsev initiated the development of a new direction - the creation of atomic-powered engines for space flights. Mastering space was an old dream of Dmitry Ivanovich, even in his youth he corresponded and met with K.E. Tsiolkovsky. I think that the understanding of the gigantic possibilities of nuclear energy, with a calorific value millions of times greater than the best chemical fuels, determined the life path of D.I. Blokhintsev.
“You can't see a face face to face” ... In those years, we did not understand much. Only now, when it finally became possible to compare the deeds and fates of the outstanding scientists of the Institute of Physics and Power Engineering (IPPE) - the former "Object B", renamed on December 31, 1966 - is there a correct, as it seems to me, understanding of the ideas that moved them at that time . With all the variety of cases that the institute had to deal with, one can single out priority scientific areas that turned out to be in the sphere of interests of its leading physicists.
The main interest of AIL (as Alexander Ilyich Leipunsky was called behind the back at the institute) is the development of global energy based on fast breeder reactors (nuclear reactors that have no restrictions on nuclear fuel resources). It is difficult to overestimate the significance of this truly "cosmic" problem, to which he devoted the last quarter of a century of his life. Leipunsky also spent a lot of energy on the defense of the country, in particular, on the creation of atomic engines for submarines and heavy aircraft.
Interests D.I. Blokhintsev (the nickname “D.I.” was assigned to him) were aimed at solving the problem of using nuclear energy for space flights. Unfortunately, in the late 1950s, he was forced to leave this job and lead the creation of an international scientific center - the Joint Institute for Nuclear Research in Dubna. There he worked on pulsed fast reactors - IBR. This was the last big thing in his life.
One goal - one team
DI. Blokhintsev, who taught in the late 1940s at Moscow State University, noticed there, and then invited the young physicist Igor Bondarenko to work in Obninsk, who literally raved about nuclear-powered spaceships. His first supervisor was A.I. Leipunsky, and Igor, of course, dealt with his subject - fast breeders.
Under D.I. Blokhintsev, a group of scientists formed around Bondarenko, who united to solve the problems of using atomic energy in space. In addition to Igor Ilyich Bondarenko, the group included: Viktor Yakovlevich Pupko, Edvin Alexandrovich Stumbur and the author of these lines. Igor was the main ideologist. Edwin conducted experimental studies of ground models of nuclear reactors in space installations. I was mainly engaged in "low thrust" rocket engines (thrust in them is created by a kind of accelerator - "ion propulsion", which is powered by energy from a space nuclear power plant). We have explored the processes
flowing in ion thrusters, on ground stands.
On Victor Pupko (in the future
he became the head of the space technology department of the IPPE) there was a lot of organizational work. Igor Ilyich Bondarenko was an outstanding physicist. He subtly felt the experiment, set up simple, elegant and very effective experiments. I think, as no experimenter, and, perhaps, few theorists, "felt" fundamental physics. Always responsive, open and friendly, Igor was truly the soul of the institute. Till now FEI lives by his ideas. Bondarenko lived an unreasonably short life. In 1964, at the age of 38, he tragically died due to a medical error. It was as if God, seeing how much man had done, decided that it was already too much and commanded: “Enough.”
It is impossible not to recall another unique personality - Vladimir Alexandrovich Malykh, a technologist "from God", the modern Leskovsky Levsha. If the “products” of the scientists mentioned above were mainly ideas and calculated estimates of their reality, then the works of Malykh always had an output “in metal”. Its technology sector, which at the time of IPPE's heyday numbered more than two thousand employees, could do, without exaggeration, everything. Moreover, he himself has always played a key role.
V.A. Malykh began as a laboratory assistant at the Research Institute of Nuclear Physics of Moscow State University, having three courses in the Physics Department behind his soul - the war did not let him finish his studies. In the late 1940s, he managed to create a technology for the manufacture of technical ceramics based on beryllium oxide, a unique material, a dielectric with high thermal conductivity. Before Malykh, many struggled unsuccessfully with this problem. And the fuel cell based on serial stainless steel and natural uranium, which he developed for the first nuclear power plant, is a miracle for those and even today. Or the thermionic fuel element of the reactor-electric generator designed by Malykh to power spacecraft - the “garland”. Until now, nothing better has appeared in this area. Malykh's creations were not demonstration toys, but elements of nuclear technology. They worked for months and years. Vladimir Alexandrovich became Doctor of Technical Sciences, laureate of the Lenin Prize, Hero of Socialist Labor. In 1964, he tragically died from the consequences of a military concussion.
Step by step
S.P. Korolev and D.I. Blokhintsev have long nurtured the dream of manned space flight. Close working ties were established between them. But in the early 1950s, at the height of the Cold War, funds were spared only for military purposes. Rocket technology was considered only as a carrier of nuclear charges, and satellites were not even thought of. Meanwhile, Bondarenko, knowing about the latest achievements of rocket scientists, persistently advocated the creation of an artificial satellite of the Earth. Subsequently, no one remembered this.
The history of the creation of the rocket that lifted the first cosmonaut of the planet, Yuri Gagarin, into space is curious. It is associated with the name of Andrei Dmitrievich Sakharov. In the late 1940s, he developed a combined fission-thermonuclear charge - "puff", apparently independently of the "father of the hydrogen bomb" Edward Teller, who proposed a similar product called the "alarm clock". However, Teller soon realized that a nuclear charge of such a design would have a “limited” yield, no more than ~ 500 kilotons of tow equivalent. This is not enough for the “absolute” weapon, so the “alarm clock” was abandoned. In the Union, in 1953, they blew up the Sakharov puff RDS-6s.
After successful tests and the election of Sakharov as an academician, the then head of Minsredmash V.A. Malyshev invited him to his place and set the task of determining the parameters of the next generation bomb. Andrei Dmitrievich estimated (without detailed study) the weight of a new, much more powerful charge. Sakharov's report formed the basis of the resolution of the Central Committee of the CPSU and the Council of Ministers of the USSR, which obliged S.P. Korolev to develop a ballistic launch vehicle for this charge. It was such a R-7 rocket called Vostok that launched an artificial Earth satellite in 1957 and a spacecraft with Yuri Gagarin in 1961 into orbit. It was no longer planned to use it as a carrier of a heavy nuclear charge, since the development of thermonuclear weapons went a different way.
At the initial stage of the IPPE space nuclear program, together with V.N. Chelomeya developed a cruise atomic missile. This direction did not develop for long and ended with calculations and testing of engine elements created in the department of V.A. Malykha. In fact, it was a low-flying unmanned aircraft with a ramjet nuclear engine and a nuclear warhead (a kind of nuclear analogue of the "buzzing bug" - the German V-1). The system was launched using conventional rocket boosters. After reaching a given speed, thrust was created by atmospheric air, heated by a chain reaction of fission of beryllium oxide impregnated with enriched uranium.
Generally speaking, the ability of a rocket to perform one or another cosmonautical task is determined by the speed it acquires after using up the entire supply of the working fluid (fuel and oxidizer). It is calculated according to the Tsiolkovsky formula: V = c × lnMn / Mk, where c is the outflow velocity of the working fluid, and Mn and Mk are the initial and final mass of the rocket. In conventional chemical rockets, the exhaust velocity is determined by the temperature in the combustion chamber, the type of fuel and oxidizer, and the molecular weight of the combustion products. For example, the Americans used hydrogen as fuel in the descent vehicle to land astronauts on the moon. The product of its combustion is water, whose molecular weight is relatively low, and the flow rate is 1.3 times higher than when burning kerosene. This is enough for the descent vehicle with astronauts to reach the surface of the Moon and then return them to the orbit of its artificial satellite. At Korolev, work with hydrogen fuel was suspended due to an accident with casualties. We did not have time to create a lunar descent vehicle for humans.
One of the ways to significantly increase the exhaust velocity is the creation of nuclear thermal rockets. We had ballistic atomic missiles (BAR) with a range of several thousand kilometers (a joint project of OKB-1 and FEI), the Americans had similar systems of the Kiwi type. The engines were tested at the test sites near Semipalatinsk and in Nevada. The principle of their operation is as follows: hydrogen is heated in a nuclear reactor to high temperatures, passes into an atomic state, and already in this form expires from a rocket. In this case, the exhaust velocity increases by more than four times in comparison with a chemical hydrogen rocket. The question was to find out to what temperature hydrogen can be heated in a solid fuel cell reactor. Calculations gave about 3000°K.
At NII-1, whose supervisor was Mstislav Vsevolodovich Keldysh (then president of the USSR Academy of Sciences), the department of V.M. Ievleva, with the participation of the IPPE, was engaged in a completely fantastic scheme - a gas-phase reactor in which a chain reaction proceeds in a gaseous mixture of uranium and hydrogen. Hydrogen flows out of such a reactor ten times faster than from a solid fuel one, while uranium is separated and remains in the core. One of the ideas was to use centrifugal separation, when a hot gaseous mixture of uranium and hydrogen is "spun" by incoming cold hydrogen, as a result of which the uranium and hydrogen are separated, as in a centrifuge. Ievlev tried, in fact, to directly reproduce the processes in the combustion chamber of a chemical rocket, using as an energy source not the heat of combustion of the fuel, but the fission chain reaction. This opened the way to the full use of the energy intensity of atomic nuclei. But the question of the possibility of the outflow of pure hydrogen (without uranium) from the reactor remained unresolved, not to mention the technical problems associated with the retention of high-temperature gas mixtures at pressures of hundreds of atmospheres.
IPPE work on ballistic atomic missiles ended in 1969-1970 with “fire tests” at the Semipalatinsk test site of a prototype nuclear rocket engine with solid fuel elements. It was created by the IPPE in cooperation with the Voronezh Design Bureau A.D. Konopatov, Moscow NII-1 and a number of other technological groups. The basis of the engine with a thrust of 3.6 tons was the IR-100 nuclear reactor with fuel elements from a solid solution of uranium carbide and zirconium carbide. The hydrogen temperature reached 3000°K at a reactor power of ~170 MW.
Nuclear thrusters
So far, we have been talking about rockets with a thrust greater than their weight, which could be launched from the surface of the Earth. In such systems, an increase in the exhaust rate makes it possible to reduce the stock of the working fluid, increase the payload, and abandon the multistage process. However, there are ways to achieve practically unlimited exhaust velocities, for example, the acceleration of matter by electromagnetic fields. I worked in this area in close contact with Igor Bondarenko for almost 15 years.
The acceleration of a rocket with an electric jet engine (EP) is determined by the ratio of the specific power of the space nuclear power plant (KAES) installed on them to the exhaust velocity. In the foreseeable future, the specific power of KNPP, apparently, will not exceed 1 kW/kg. At the same time, it is possible to create rockets with low thrust, tens and hundreds of times less than the weight of the rocket, and with a very low consumption of the working fluid. Such a rocket can only be launched from the orbit of an artificial satellite of the Earth and, slowly accelerating, reach high speeds.
Flights within the solar system require rockets with an expiration speed of 50-500 km/s, and flights to the stars require "photon rockets" that go beyond our imagination with an expiration speed equal to the speed of light. In order to carry out a long-range space flight of any reasonable duration, unimaginable power-to-weight ratios of power plants are needed. So far, it is impossible even to imagine on what physical processes they can be based.
The calculations performed showed that during the Great Confrontation, when the Earth and Mars are closest to each other, it is possible to fly a nuclear spacecraft with a crew to Mars in one year and return it to the orbit of an artificial satellite of the Earth. The total weight of such a ship is about 5 tons (including the reserve of the working fluid - cesium, equal to 1.6 tons). It is determined mainly by the mass of the KNPP with a power of 5 MW, and the reactive thrust is determined by a two-megawatt beam of cesium ions with an energy of 7 kiloelectronvolts*. The ship starts from the orbit of an artificial satellite of the Earth, enters the orbit of a satellite of Mars, and will have to descend to its surface on an apparatus with a hydrogen chemical engine, similar to the American lunar one.
This direction, based on technical solutions that are already possible today, was devoted to a large cycle of IPPE works.
Ion thrusters
In those years, ways were discussed to create various electric propulsion systems for space vehicles, such as "plasma guns", electrostatic accelerators of "dust" or liquid drops. However, none of the ideas had a clear physical basis. The discovery was the surface ionization of cesium.
Back in the 1920s, the American physicist Irving Langmuir discovered the surface ionization of alkali metals. When a cesium atom evaporates from the surface of a metal (in our case, tungsten), whose work function of electrons is greater than the ionization potential of cesium, it loses a weakly bound electron in almost 100% of cases and turns out to be a singly charged ion. Thus, the surface ionization of cesium on tungsten is the physical process that makes it possible to create an ion propulsor with almost 100% use of the working fluid and with an energy efficiency close to unity.
Our colleague Stal Yakovlevich Lebedev played an important role in creating models of an ion propulsor of such a scheme. With his iron perseverance and perseverance, he overcame all obstacles. As a result, it was possible to reproduce in metal a flat three-electrode circuit of an ion propulsor. The first electrode is a tungsten plate approximately 10 × 10 cm in size with a potential of +7 kV, the second is a tungsten grid with a potential of -3 kV, and the third is a thoriated tungsten grid with zero potential. The "molecular gun" gave a beam of cesium vapor, which fell through all the grids onto the surface of the tungsten plate. A balanced and calibrated metal plate, the so-called balance, served to measure the "force", i.e., the thrust of the ion beam.
An accelerating voltage to the first grid accelerates cesium ions to 10,000 eV, while a decelerating voltage to the second grid slows them down to 7,000 eV. This is the energy with which the ions must leave the propeller, which corresponds to an outflow velocity of 100 km/s. But an ion beam, limited by a space charge, cannot “go out into outer space”. The volumetric charge of ions must be compensated by electrons in order to form a quasi-neutral plasma, which freely propagates in space and creates reactive thrust. The source of electrons for compensating the space charge of the ion beam is the third grid (cathode) heated by the current. The second, "locking" grid prevents electrons from getting from the cathode to the tungsten plate.
The first experience with the ion propulsion model marked the beginning of more than ten years of work. One of the latest models - with a porous tungsten emitter, created in 1965, gave a "thrust" of about 20 g at an ion beam current of 20 A, had an energy utilization factor of about 90% and a matter utilization rate of 95%.
Direct conversion of nuclear heat into electricity
Ways to directly convert the energy of nuclear fission into electrical energy have not yet been found. We still cannot do without an intermediate link - a heat engine. Since its efficiency is always less than unity, the "waste" heat must be put somewhere. On land, in water and in the air, there are no problems with this. In space, there is only one way - thermal radiation. Thus, KNPP cannot do without a “refrigerator-emitter”. The radiation density is proportional to the fourth power of the absolute temperature, so the temperature of the radiator-radiator should be as high as possible. Then it will be possible to reduce the area of the radiating surface and, accordingly, the mass of the power plant. We came up with the idea to use the "direct" conversion of nuclear heat to electricity, without a turbine or generator, which seemed more reliable in long-term operation at high temperatures.
From the literature, we knew about the works of A.F. Ioffe - the founder of the Soviet school of technical physics, a pioneer in the study of semiconductors in the USSR. Few now remember the current sources he developed, which were used during the Great Patriotic War. At that time, more than one partisan detachment had a connection with the mainland thanks to "kerosene" TEGs - Ioffe's thermoelectric generators. The "crown" of TEGs (it was a set of semiconductor elements) was put on a kerosene lamp, and its wires were connected to radio equipment. The “hot” ends of the elements were heated by the flame of a kerosene lamp, and the “cold” ends were cooled in air. The heat flow, passing through the semiconductor, generated an electromotive force, which was enough for a communication session, and in the intervals between them, the TEG charged the battery. When, ten years after the Victory, we visited the Moscow plant of TEGs, it turned out that they still find sales. Many villagers then had economical radio receivers "Rodina" with direct incandescent lamps, powered by a battery. TEGs were often used instead.
The trouble with the kerosene TEG is its low efficiency (only about 3.5%) and low limiting temperature (350°K). But the simplicity and reliability of these devices attracted developers. So, semiconductor converters developed by the group of I.G. Gverdtsiteli at the Sukhumi Institute of Physics and Technology, have found application in space installations of the Buk type.
At one time, A.F. Ioffe proposed another thermionic converter - a diode in vacuum. The principle of its operation is as follows: a heated cathode emits electrons, part of them, overcoming the potential of the anode, does work. A significantly higher efficiency (20-25%) was expected from this device at an operating temperature above 1000°K. In addition, unlike a semiconductor, a vacuum diode is not afraid of neutron radiation, and it can be combined with a nuclear reactor. However, it turned out that it was impossible to realize the idea of the “vacuum” Ioffe converter. As in the ion propulsion, in the vacuum converter, you need to get rid of the space charge, but this time not ions, but electrons. A.F. Ioffe intended to use micron gaps between the cathode and anode in a vacuum converter, which is practically impossible under conditions of high temperatures and thermal deformations. This is where cesium comes in handy: one cesium ion, produced by surface ionization at the cathode, compensates for the space charge of about 500 electrons! In fact, the cesium converter is a "reversed" ion propulsor. The physical processes in them are close.
"Garlands" V.A. Malykha
One of the results of IPPE work on thermionic converters was the creation of V.A. Malykh and serial production in his department of fuel elements from series-connected thermionic converters - "garlands" for the Topaz reactor. They gave up to 30 V - a hundred times more than single-element converters created by "competing organizations" - the Leningrad group of M.B. Barabash and later - by the Institute of Atomic Energy. This made it possible to "remove" tens and hundreds of times more power from the reactor. However, the reliability of the system, stuffed with thousands of thermionic elements, caused concern. At the same time, steam and gas turbines operated without failures, so we turned our attention to the "machine" conversion of nuclear heat into electricity.
The whole difficulty lay in the resource, because in long-range space flights, turbogenerators must work for a year, two, or even several years. In order to reduce wear, the “revolutions” (turbine speed) should be kept as low as possible. On the other hand, a turbine works efficiently if the speed of the gas or steam molecules is close to the speed of its blades. Therefore, at first we considered the use of the heaviest - mercury vapor. But we were frightened by the intense radiation-induced corrosion of iron and stainless steel that occurred in a mercury-cooled nuclear reactor. In two weeks, corrosion "ate" the fuel elements of the experimental fast reactor "Clementine" in the Argon laboratory (USA, 1949) and the BR-2 reactor at the IPPE (USSR, Obninsk, 1956).
Potassium steam was tempting. The reactor with potassium boiling in it formed the basis of the power plant we are developing for a low-thrust spacecraft - potassium steam rotated the turbogenerator. Such a “machine” method of converting heat into electricity made it possible to count on an efficiency of up to 40%, while real thermionic installations gave an efficiency of only about 7%. However, KNPPs with "machine" conversion of nuclear heat into electricity have not been developed. The case ended with the release of a detailed report, in fact, a “physical note” to the technical design of a low-thrust spacecraft for a flight with a crew to Mars. The project itself was never developed.
In the future, I think, the interest in space flights using nuclear rocket engines simply disappeared. After the death of Sergei Pavlovich Korolev, support for the work of the IPPE on ion propulsion and "machine" nuclear power plants noticeably weakened. OKB-1 was headed by Valentin Petrovich Glushko, who had no interest in bold promising projects. The Energiya design bureau created by him built powerful chemical rockets and the Buran spacecraft returning to Earth.
"Buk" and "Topaz" on satellites of the "Cosmos" series
Work on the creation of a KNPP with direct conversion of heat into electricity, now as power sources for powerful radio satellites (space radar stations and television broadcasters), continued until the start of perestroika. From 1970 to 1988, about 30 radar satellites were launched into space with Buk nuclear power plants with semiconductor converter reactors and two with Topaz thermionic installations. The Buk, in fact, was a TEG - an Ioffe semiconductor converter, only instead of a kerosene lamp it used a nuclear reactor. It was a fast reactor with a power of up to 100 kW. The full load of highly enriched uranium was about 30 kg. The heat from the core was transferred by liquid metal - a eutectic alloy of sodium and potassium to semiconductor batteries. Electric power reached 5 kW.
The Buk facility under the scientific supervision of the IPPE was developed by OKB-670 specialists M.M. Bondaryuk, later - NPO Krasnaya Zvezda (chief designer - G.M. Gryaznov). The Dnepropetrovsk Design Bureau Yuzhmash (Chief Designer M.K. Yangel) was assigned to create a launch vehicle for launching the satellite into orbit.
The operating time of the Buk is 1-3 months. If the installation failed, the satellite was transferred to a long-term orbit with a height of 1000 km. For almost 20 years of launches, there have been three cases of a satellite falling to Earth: two into the ocean and one into land, in Canada, in the vicinity of the Great Slave Lake. Cosmos-954, launched on January 24, 1978, fell there. He worked for 3.5 months. The satellite's uranium elements burned up completely in the atmosphere. On the ground, only the remains of a beryllium reflector and semiconductor batteries were found. (All this data is given in the joint report of the US and Canadian nuclear commissions on Operation Morning Light.)
In the Topaz thermionic nuclear power plant, a thermal reactor with a power of up to 150 kW was used. The full load of uranium was about 12 kg - significantly less than that of the Buk. The basis of the reactor was fuel elements - "garlands", developed and manufactured by Malykh's group. They were a chain of thermoelements: the cathode was a “thimble” of tungsten or molybdenum filled with uranium oxide, the anode was a thin-walled niobium tube cooled with liquid sodium-potassium. The cathode temperature reached 1650°C. The electrical power of the installation reached 10 kW.
The first flight model, the Kosmos-1818 satellite with the Topaz installation, went into orbit on February 2, 1987 and worked flawlessly for six months, until the cesium reserves were exhausted. The second satellite, Cosmos-1876, was launched a year later. He worked in orbit almost twice as long. The main developer of Topaz was OKB MMZ Soyuz, headed by S.K. Tumansky (former design bureau of aircraft engine designer A.A. Mikulin).
It was in the late 1950s, when we were working on ion propulsion, and he was on a third-stage engine for a rocket that would fly around the moon and land on it. Memories of Melnikov's laboratory are fresh to this day. It was located in Podlipki (now the city of Korolev), on site No. 3 of OKB-1. A huge workshop with an area of about 3000 m2, lined with dozens of desks with loop oscilloscopes recording on 100 mm roll paper (this was still a bygone era, today one personal computer would be enough). At the front wall of the workshop there is a stand where the combustion chamber of the "lunar" rocket engine is mounted. Thousands of wires go to oscilloscopes from sensors for gas velocity, pressure, temperature and other parameters. The day starts at 9.00 with the ignition of the engine. It runs for several minutes, then immediately after it is stopped, the first shift mechanic team dismantles it, carefully inspects and measures the combustion chamber. At the same time, oscilloscope tapes are analyzed and recommendations for design changes are made. The second shift - designers and workshop workers make the recommended changes. In the third shift, a new combustion chamber and a diagnostic system are mounted on the stand. A day later, exactly at 9.00, the next session. And so without days off weeks, months. More than 300 engine options per year!
This is how chemical rocket engines were created, which had to work for only 20-30 minutes. What can we say about the testing and refinement of nuclear power plants - the calculation was that they should work for more than one year. It required a truly gigantic effort.
Nuclear enginesAt the end of the 1940s, in the wake of euphoria from the prospects for the use of nuclear energy, both in the USA and in the USSR, work was underway to install nuclear engines on everything that could move. The idea of creating such a “perpetual motion machine” was especially attractive for the military. Nuclear power plants (NPPs) primarily found application in the navy, since ship power plants did not have such strict overall weight requirements as, for example, in aviation. Nevertheless, the Air Force could not "pass by" the possibility of an unlimited increase in the radius of action of strategic aviation. In May 1946 The US Air Force Command has approved the Nuclear Energy for the Propulsion of Aircraft (abbreviated NEPA) project for the creation of nuclear engines to equip strategic bombers. Work on its implementation began at the Oak Ridge National Laboratory. In 1951 it was replaced by the joint program of the Air Force and the Atomic Energy Commission (AEC) "Aircraft Nuclear Propulsion" (ANP, "Aircraft Nuclear Propulsion"). The General Electric company created a turbojet (TRD) that differed from the “ordinary” one only in that instead of a conventional combustion chamber there was a nuclear reactor that heated the air compressed by the compressor. At the same time, the air became radioactive - an open circuit. In those years, this was treated more simply, but still, in order not to pollute their airfield, it was supposed to equip the aircraft for takeoff and landing with conventional kerosene engines. The first US nuclear aircraft project was based on the B-58 supersonic strategic bomber. From the developer (Convair), he received the designation X-6. Under the delta wing there were four atomic turbojet engines, in addition, 2 more "ordinary" turbojet engines were supposed to work on takeoff and landing. By the mid-1950s, a prototype of a small air-cooled nuclear reactor with a capacity of 1 MW was manufactured. A B-36H bomber was allocated for its flight and crew protection tests. The crew of the flying laboratory was in a protective capsule, but the reactor itself, located in the bomb bay, had no biological protection. The flying laboratory was named NB-36H. From July 1955 to March 1957 she made 47 flights over the desert regions of Texas and New Mexico, during which the reactor was turned on and off. At the next stage, a new nuclear reactor HTRE was created (its last model had a power of 35 MW, sufficient to operate two engines) and an experimental X-39 engine that successfully passed joint ground bench tests. However, by this time, the Americans realized that an open circuit was not suitable, and began designing a power plant with air heating in a heat exchanger. The new Convair NX-2 machine had a “duck” scheme (horizontal tail was located in front of the wing). The nuclear reactor was supposed to be located in the center section, the engines - in the stern, the air intakes - under the wing. The aircraft was supposed to use from 2 to 6 auxiliary turbojets. But in March 1961 the ANP program was closed. In 1954-1955. a group of scientists at the Los Alamos Laboratory prepared a report on the possibility of creating a nuclear rocket engine (NRE). The US AEC has decided to start work on its creation. The program was named "Rover". Work was carried out in parallel at the Los Alamos Scientific Laboratory and at the Radiation Laboratory at Livermore at the University of California. Since 1956, all the efforts of the Radiation Laboratory were directed to the creation of a nuclear ramjet engine (YAPJE) under the PLUTO project (in Los Alamos, they started creating the NJE).
The YaPVRD was planned to be installed on the developed supersonic low-altitude missile (Supersonic Low-Altitude Missile - SLAM). The missile (now it would be called a cruise missile) was essentially an unmanned bomber with a vertical launch (with the help of four solid-fuel boosters). The ramjet was switched on when a certain speed was reached already at a sufficient distance from its own territory. The air entering through the air intake was heated in a nuclear reactor and, flowing through the nozzle, created thrust. The flight to the target and the release of warheads for the purpose of secrecy had to be carried out at an ultra-low altitude at a speed of three times the speed of sound. The nuclear reactor had a thermal power of 500 MW, the operating temperature of the core was more than 1600 degrees C. A special test site was built to test the engine. |  |
The Soviet Union needed a nuclear aircraft much more than the United States, since it did not have military bases near the US borders and could only operate from its territory, and the M-4 and Tu-95 strategic bombers that appeared in the mid-1950s could not “cover” the entire US territory. Work on studying the problems of creating nuclear power plants for ships, submarines and aircraft began already in 1947. however, the resolution of the Council of Ministers on the start of work on aircraft with a nuclear engine is issued only on August 12, 1955. (by this time the first Soviet nuclear submarine was already under construction). OKB-156 Tupolev and OKB-23 Myasishchev engaged in the design of aircraft with nuclear power plants, and OKB-276 Kuznetsov and OKB-165 Lyulka developed such power plants themselves. In March 1956 a government decree was issued on the creation (to study the effect of radiation on the design of an aircraft and its equipment, as well as issues of radiation safety) of a flying laboratory based on the Tu-95 strategic bomber. In 1958 An experimental, “aircraft” nuclear reactor was delivered to the Semipalatinsk test site. In the middle of 1959 The reactor was installed on a serial aircraft designated Tu-95LAL (Flying Atomic Laboratory). The reactor is used 
It was called only as a source of radiation and was cooled by water. The radiator of the cooling system, located at the bottom of the fuselage, was blown by the oncoming air flow. May-August 1961. Tu-95LAL made 34 flights over the territory of the test site. The next step was to be the creation of an experimental Tu-119 based on the Tu-95. On two (of 
four of its NK-12M engines (Kuznetsov Design Bureau), in addition to the combustion chambers, were equipped with heat exchangers heated by a liquid metal coolant that took heat from a nuclear reactor located in the cargo compartment. The engines received the designation NK-14A. In the future, it was supposed, by installing 4 NK-14A engines on the aircraft and increasing the diameter of the fuselage, to create an anti-submarine aircraft with a practically unlimited flight duration. However, the design of the NK-14A engines, or rather its nuclear part, proceeded slowly due to the many problems that arose in this case. As a result, plans for the creation of the Tu-119 were never implemented. In addition, OKB-156 offered several variants of supersonic bombers. Long-range bomber Tu-120 with a take-off weight of 85 tons. 30.7m long. wingspan 24.4 m. and 
maximum speed is about 1400 km/h. Another project was a low-altitude strike aircraft with a take-off weight of 102 tons. 37m long. wingspan 19m. and a maximum speed of 1400 km/h. The aircraft had a low delta wing. Its two engines were located in one package at the rear of the fuselage. During takeoff and landing, the engines ran on kerosene. The supersonic strategic bomber was supposed to have a takeoff weight of 153 tons. length 40.5m. and a wingspan of 30.6m. Of the six turbojet engines (KB Kuznetsov), two located in the tail were equipped with heat exchangers and could operate from a nuclear reactor. Four conventional turbojet engines were placed under the wing on pylons. Outwardly, this aircraft was similar to the American B-58 supersonic medium bomber. The Myasishchev Design Bureau also considered the possibility of creating a “nuclear” aircraft based on the already existing ZM bomber by replacing conventional turbojet engines with nuclear ones equipped with heat exchangers (the reactor was located in the bomb bay). The possibility of creating a supersonic bomber M-60 was also considered. Several 
line-up options with different types of engines (take-off weight 225-250t, payload - 25t, speed - up to 3000 km/h, length 51-59m, wingspan - 27-31m). To protect against radiation, the pilots were placed in a special sealed capsule and the engines were placed in the rear fuselage. The visual review from the capsule was excluded and the autopilot had to guide the aircraft to the target. To provide manual control, it was supposed to use television and radar screens. The developers initially proposed to make the aircraft unmanned. But the military, for reliability, insisted on a manned version. One option was a seaplane. Its advantage was that the muffled reactors could be lowered into the water to reduce the background radiation. With the development of rocket science and the advent of reliable intercontinental ballistic missiles and nuclear missile submarines, military interest in nuclear bombers faded and work was curtailed. But in 1965 they returned to the idea of creating a nuclear anti-submarine aircraft again. This time, the heavy transport An-22 Antey, which had the same engines as the Tu-95, became the prototype. The development of the NK-14A by that time had advanced quite a bit. Takeoff and landing were to be carried out on kerosene (engine power 4 x 13000 hp), and cruising flight - on nuclear energy (4 x 8900 hp). The duration of the flight was limited only by the "human factor"; in order to limit the dose received by the crew, it was set equal to 50 hours. The flight range in this case would be 27500 km. In 1972 An-22 with a nuclear reactor on board made 23 flights in them, first of all, radiation protection was checked. However, environmental problems in the event of an aircraft accident were never resolved, perhaps this was the reason that the project was not implemented. In the 80s, interest arose in a nuclear aircraft as a carrier of ballistic missiles. Almost constantly being in the air, he would be invulnerable to a surprise nuclear missile attack by the enemy. In the event of an aircraft accident, the nuclear reactor could be separated and descended by parachute. But the beginning of detente, "perestroika" and then the collapse of the USSR did not allow the atomic plane to take off. In OKB-301 (chief designer S.A. Lavochkin) in the mid-50s, the issue of installing a ramjet nuclear engine on the intercontinental cruise missile Burya (similar to the PLUTO project) was studied. The project received the designation "375". The development of the rocket itself was not a problem, let down the engines. OKB-670 (chief designer M.M. Bondaryuk) could not cope with the creation of a ramjet nuclear engine for a long time. In 1960 the Tempest project was closed along with its nuclear version. The matter never came to testing a nuclear engine. Nuclear energy can be used to heat the working fluid not only in an air-jet engine, but also in a nuclear rocket engine (NRE), which is usually divided into reactive, in which the process of heating the working fluid (RT) occurs continuously, and pulsed or pulsating (also in generally reactive), in which nuclear energy is released discretely, by a series of nuclear (thermonuclear) explosions of low power. According to the state of aggregation of nuclear fuel in the reactor core, NREs are divided into solid-phase, liquid-phase and gas-phase (plasma). Separately, it is possible to single out the NRE in the reactor of which the nuclear fuel is in a fluidized state (in the form of a rotating "cloud" of dust-like particles). Another type of jet NRE is an engine that uses thermal energy released during spontaneous fission of radioactive isotopes (radioactive decay) to heat the RT. The advantage of such an engine is the simplicity of design, a significant disadvantage is the high cost of isotopes (for example, polonium-210). In addition, during the spontaneous decay of an isotope, heat is constantly released, even when the engine is turned off, and it must somehow be removed from the engine, which complicates and makes the design heavier. In a pulsed NRE, the energy of an atomic explosion vaporizes the RT, turning it into plasma. An expanding plasma cloud exerts pressure on a powerful metal bottom (pusher plate) and creates jet thrust. The RT can be an easily convertible solid substance applied to a pusher plate, liquid hydrogen or water stored in a special tank. This is a scheme of the so-called pulsed NRE of external action, another type is a pulsed NRE of internal action, in which small nuclear or thermonuclear charges are detonated inside special chambers (combustion chambers) equipped with jet nozzles. The RT is also supplied there, which, flowing through the nozzle, creates thrust like conventional rocket engines. Such a system is more efficient, since all RT and explosion products are used to create thrust. However, the fact that explosions occur inside a certain volume imposes restrictions on the pressure and temperature in the combustion chamber. The pulsed NRE of external action is simpler, and the huge amount of energy released in nuclear reactions makes it possible to obtain good characteristics of such systems even at a lower efficiency. In the USA in 1958-63. a project of a rocket with a pulsed YARD "Orion" was developed. They even tested a model aircraft with a pulse engine on conventional chemical explosives. The results obtained spoke about the fundamental possibility of a controlled flight of the apparatus with such an engine. Orion was originally supposed to be launched from Earth. To exclude the possibility of damage to the rocket from a ground-based nuclear explosion, it was planned to install it on eight 75-meter towers for launch. At the same time, the launch mass of the rocket reached 10,000 tons. and the diameter of the pushing plate is about 40m. To reduce dynamic loads on the rocket structure and crew, a damping device was provided. After a compression cycle, it returned the plate to its original position, after which another explosion occurred. At the start, every second a charge with a power of 0.1 kt was undermined. After leaving the atmosphere, charges with a power of 20 kt. exploded every 10 seconds. Later, in order not to pollute the atmosphere, it was decided to lift the Orion from the Earth using the first stage of the Saturn-5 rocket, and since its maximum diameter was 10m. then the diameter of the pushing plate was cut to 
10 m. Effective thrust, respectively, decreased to 350 tons with its own “dry” weight of the control unit (without RT) 90.8 tons. For delivery to the lunar surface of a payload of 680 tons. it would be necessary to blow up about 800 plutonium charges (the mass of plutonium is 525 kg.) and use up about 800 tons. RT. The option of using the Orion as a means of delivering nuclear charges to the target was also considered. But soon the military abandoned this idea. And in 1963. An agreement was signed on the prohibition of nuclear explosions in space on earth (in the atmosphere) and under water. This outlawed the entire project. A similar project was considered in the USSR, but it did not have any practical results. As well as the project of the aerospace aircraft (VKS) M-19 of the Myasishchev Design Bureau. The project envisaged the creation of a reusable, single-stage aerospace system capable of launching a payload weighing up to 40 tons into low reference orbits (up to 185 km). To do this, the VCS was supposed to be equipped with a nuclear rocket engine and a multi-mode air-jet propulsion system operating both from a nuclear reactor and on hydrogen fuel. More about this project is described on the page. Nuclear energy can not only be directly used to heat the RT in the engine, but also be converted into electrical energy, which is then used to create thrust in electric propulsion engines (EP). According to this scheme, nuclear power propulsion systems (NPP) were built, consisting of nuclear power plants (NPP) and electric rocket propulsion systems (EPP). There is no well-established (generally accepted) classification of electric propulsion. According to the prevailing "mechanism" of acceleration, RT EJE can be divided into gas-dynamic (electrochemical), electrostatic (ion) and electromagnetic (plasma). In electrochemical plants, electricity is used to heat or chemically decompose RT (electric heating, thermal catalytic and hybrid), while the RT temperature can reach 5000 deg. The acceleration of the RT occurs, as in conventional LRE, when it passes through the gas-dynamic path of the engine (nozzle). Electrochemical engines consume the smallest power per unit of thrust among electric propulsion engines (about 10 kW/kg). In an electrostatic electric propulsion engine, the working fluid is first ionized, after which positive ions are accelerated in an electrostatic field (using a system of electrodes) creating thrust (electrons are injected into it at the exit from the engine to neutralize the charge of the jet stream). In an electromagnetic electric propulsion engine, the RT is heated to a plasma state (tens of thousands of degrees) by an electric current passing through it. Then the plasma is accelerated in an electromagnetic field (“in parallel” gas-dynamic acceleration can also be applied). Low-molecular or easily dissociating gases and liquids are used as RT in electrothermal EJEs, alkaline or heavy, easily evaporating metals or organic liquids in electrostatic EJEs, and various gases and solids in electromagnetic EJEs. An important parameter of the engine is its specific thrust impulse (see page ) characterizing its efficiency (the more it is, the less RT is spent on creating a kilogram of thrust). The specific impulse for different types of engines varies over a wide range: solid propellant RD - 2650 m/sec, liquid propellant rocket engine - 4500 m/sec, electrochemical EP - 3000 m/sec, plasma EP up to 290 thousand. As is known, the value of the specific impulse is directly proportional to the square root of the value of the RT temperature in front of the nozzle. It (temperature) in turn is determined by the calorific value of the fuel. The best indicator among chemical fuels is a pair of beryllium + oxygen - 7200 kcal / kg. The calorific value of Uranium-235 is about 2 million times higher. However, the amount of energy that can be usefully used is only 1400 times greater. Restrictions imposed by design features reduce this figure for a solid-phase NRE to 2-3 (the maximum achievable RT temperature is about 3000 degrees). And yet, the specific impulse of a solid-phase nuclear rocket engine is approximately 9000 m / s, against 3500-4500 for modern rocket engines. For liquid-phase NREs, the specific impulse can reach 20,000 m/s, for gas-phase ones, where the temperature of the RT can reach tens of thousands of degrees, the specific impulse is 15-70 thousand m/s. Another important parameter characterizing the weight perfection of a propulsion system (PS) or engine is their specific gravity - the ratio of the weight of the propulsion system (with or without fuel components) or the engine to the generated thrust. The reciprocal of it is also used - specific thrust. The specific gravity (thrust) determines the achievable acceleration of the aircraft, its thrust-to-weight ratio. For modern liquid-propellant rocket engines, the specific gravity is 7–20 kg. thrust per ton deadweight i.e. the ratio of thrust to weight reaches 14. The NRE also has a good ratio of thrust to its own weight - up to 10. At the same time, for LRE using oxygen-hydrogen fuel, the ratio of the mass of the RT to the mass of the structure is in the range of 7-8. For solid-phase NREs, this parameter is reduced to 3-5, which provides a gain in the specific gravity of the PS, taking into account the weight of the RT. In an electric propulsion engine, the developed thrust is limited by the high energy consumption for creating 1 kg. thrust (from 10 kW to 1 MW). The maximum thrust of the existing electric propulsion systems is several kilograms. If there are additional elements in the EP, connected with the power supply of the EP, the thrust-to-weight ratio of the apparatus with such a PS is much less than unity. This makes it impossible to use them to launch payloads into near-Earth orbit (some EJEs can generally only operate in space vacuum conditions). ERE makes sense to use only in space vehicles as low-thrust engines for orientation, stabilization and correction of orbits. Due to the low consumption of the working fluid (large specific impulse), the time of continuous operation of the ERE can be measured in months and years. Providing EJE with electricity from a nuclear reactor will make it possible to use them for flights to the “outskirts” of the Solar System, where the power of solar batteries will not be enough. Thus, the main advantage of a nuclear rocket engine over other types of rocket engines is their high specific impulse, with a high thrust-to-weight ratio (tens, hundreds and thousands of tons of thrust with a much lower dead weight). The main disadvantage of NRE is the presence of a powerful flux of penetrating radiation and the removal of highly radioactive uranium compounds with spent RT. In this regard, the NRE is unacceptable for ground launches. Work on the creation of nuclear rocket engines and nuclear power plants in the USSR began in the mid-1950s. In 1958 The Council of Ministers of the USSR adopted a number of resolutions on the conduct of research work on the creation of missiles with nuclear rocket engines. Scientific leadership was entrusted to M.V. Keldysh, I.V. Kurchatov and S.P. Korolev. Dozens of research, design, construction and installation organizations were involved in the work. These are NII-1 (now the Keldysh Research Center), OKB-670 (chief designer M.M. Bondaryuk), the Institute of Atomic Energy (IAE, now the Kurchatov Institute) and Leipunsky), Research Institute of Instrument Engineering (Chief Designer A.S. Abramov), NII-8 (now Research and Design Institute - NIKIET named after Dolezhal) and OKB-456 (now NPO Energomash named after Glushko), NIITVEL (NPO Luch, now the Podolsk Research Institute of Technology - PNITI), NII-9 (now the High-Technological Research Institute of Inorganic Materials - VNIINM named after A.A. Bochvar) and others. Subsequently, the name was changed to the Central Design Bureau of Experimental Machine Building - TsKBEM, NPO Energia, RSC Energia named after Korolev) draft designs of a single-stage ballistic missile YAR-1 and a two-stage nuclear-chemical rocket YAKhR-2 were developed. Both provided for the use of YARD with a thrust of 140 tons. The designs were ready by December 30, 1959. however, the creation of a combat YAR-1 was considered inappropriate and work on it was stopped. YAKhR-2 had a scheme similar to the R-7, but with six first-stage side rocket pods equipped with NK-9 engines. The second stage (central block) was equipped with a YARD. The launch weight of the rocket was 850-880t. with a payload mass of 35-40t. (A variant with a launch weight of 2000 tons was also considered. Length 42 m. Maximum transverse dimension 19 m. Payload up to 150 tons.). The engines of all YAKhR-2 units were launched on Earth. At the same time, the NRE was brought to the “idle” mode (the reactor power was 0.1% of the nominal one in the absence of the working fluid flow rate). The activation of the operating mode was carried out in flight a few seconds before the separation of the side blocks. In the middle of 1959 OKB-1 issued technical assignments to engine builders (OKB-670 and OKB-456) for the development of draft designs for nuclear rocket engines with a thrust of 200 and 40 tons. After the start of work on the H-1 heavy carrier, the issue of creating a two-stage carrier with a nuclear rocket engine at the second stage was considered on its basis. This would ensure an increase in the payload launched into near-Earth orbit by at least 2-2.5 times, and the orbit of the Moon's satellite by 75-90%. But this project was not completed either - the N-1 rocket never flew. The design of the YARD was carried out by OKB-456 and OKB-670. They have completed several draft designs for nuclear rocket engines with a solid-phase reactor. So in OKB-456 by 1959. draft designs of RD-401 engines with a water moderator and RD-402 engines with a beryllium moderator, which had a thrust in a void of 170 tons, were prepared. with a specific thrust impulse of 428 sec. Liquid ammonia served as the working fluid. By 1962 according to the terms of reference of OKB-1, the project RD-404 with a thrust of 203 tons was completed. with a specific thrust impulse of 950 sec. (RT - liquid hydrogen), and in 1963. - RD-405 with a thrust of 40-50t. However, in 1963 all the efforts of OKB-456 were redirected to the development of gas-phase nuclear rocket engines. Several NRE projects with a solid-phase reactor and an ammonium-alcohol mixture as a RT were developed in the same years by OKB-670. In order to move from preliminary design to the creation of real NRE samples, it was necessary to solve many more issues and, first of all, to study the operability of fuel elements (FEL) of a nuclear reactor at high temperatures. Kurchatov in 1958 proposed to create an explosive reactor for this (RVD, the modern name is a pulsed graphite reactor - IGR). Its design and manufacture was entrusted to NII-8. In the high pressure reactor, the thermal energy of uranium fission was not removed outside the active zone, but heated to very high temperatures the graphite from which (together with uranium) it was formed. It is clear that such a reactor could only work for a short time - by impulses, with shutdowns for cooling down. The absence of any metal parts in the core made it possible to produce "flashes" whose power was limited only by the sublimation temperature of graphite. In the center of the active zone there was a cavity in which the test samples were located. In the same 1958 At the Semipalatinsk test site, not far from the test site of the first atomic bomb, the construction of the necessary buildings and structures began. May-June 1960 a physical (“cold”) start-up of the reactor was carried out, and a year later a series of starts was carried out with heating of the graphite stack up to 1000 deg. To ensure environmental safety, the stand was built according to a "closed" scheme - the spent coolant was kept in gas tanks before being released into the atmosphere, and then filtered. Since 1962 At the IGR (RVD), fuel rods and fuel assemblies (FAs) of various types were tested for nuclear reactors developed at NII-9 and NII-1. In the second half of the 1950s, NII-1 and IPPE carried out studies of the gas dynamics of gas fuel elements and the physics of gas-phase reactors, which showed the fundamental possibility of creating gas-phase NREs. In the working chamber of such an engine, with the help of a magnetic field created by the solenoid surrounding it, a “stagnant” zone was created in which uranium was heated to temperatures of about 9000 degrees. and heated the hydrogen flowing through this zone (special additives were added to it to improve the absorption of radiant energy). Some part of the nuclear fuel was inevitably carried away by the gas flow, so it was necessary to constantly compensate for the loss of uranium. A gas-phase NRE could have a specific impulse of up to 20,000 m/s. Work on such an engine began in 1963. in OKB-456 (with the scientific leadership of NII-1). In 1962 The IR-20 experimental bench with a solid-phase reactor, the moderator in which was water, was created at the IPPE. It was used for the first time to study the physical parameters of solid-phase NRE reactors, which served as the basis for subsequent designs. In 1968 Taking into account the experience gained at the IR-20 stand, the Strela physical stand was also built here, on which a reactor was installed, which was a design quite close to the reactor of the flight model of the NRE. The next step towards the creation of the NRE was the creation of a special experimental facility for testing the ground-based prototype of the NRE reactor. In 1964 A government decree was issued on the construction of a bench complex for testing nuclear rocket engines at the Semipalatinsk test site, which received the name "Baikal". By February 1965 At the IAE, the terms of reference for the development of a reactor for the Baikal complex were prepared (it received the index IVG-1 research high-temperature gas-cooled). NII-8 starts its design (under the scientific guidance of the IAE). The development and manufacture of fuel assemblies are assigned to NIITVEl. In 1966 the development of the first Soviet solid-phase NRE (received the index 11B91 or RD-0410) was transferred to the Voronezh Design Bureau of Chemical Automation (KBKhA) Ch. designer A.D. Konopatov. In 1968 NPO Energomash (OKB-456) completed the development of a preliminary design for an engine with a gas-phase reactor. The engine, designated RD-600, was supposed to have a thrust of about 600 tons. with a dead weight of about 60 tons. Beryllium and graphite were used as moderator and reflector. RT - hydrogen with the addition of lithium. May 24, 1968 a government decree was issued providing for the creation of a nuclear rocket engine on the basis of the proposed project, as well as the construction of a bench base for its testing, called Baikal-2. In parallel with the development of the YARD 11B91 flight model at KBKhA, its bench prototype (IR-100) was created at NII-1. In 1970 a combination of these works was carried out (the program received the index 11B91-IR-100) and all design work on bench and flight models of nuclear rocket engines was concentrated in KBKhA. The physical start-up of the first YARD 11B91-IR-100 reactor was carried out at IPPE at the Strela stand. It carried out an extensive research program. The construction of the Baikal complex lasted several years. The complex was supposed to consist of two shafts where the experimental reactors were lowered using a gantry crane. September 18, 1972 the physical start-up of the IVG-1 reactor took place as part of the first working place of the Baikal complex. It could also be used as a bench prototype of the future YRD with a thrust of 20–40 tons. and as a stand for testing new types of nuclear fuel. The reactor had a beryllium reflector and water was the moderator. Its core consisted of 31 fuel assemblies. Hydrogen, cooling nuclear fuel, could be heated up to 2500 degrees, and even 3000 degrees could be obtained in a special central channel. The power start-up took place only at the beginning of March 1975. which was explained by the need to complete the construction of all buildings and structures of the bench complex, perform a large amount of commissioning robots and train personnel. Instruments were located in an underground bunker located between the mines. In another located at a distance of 800m. was the control panel. The control panel could be accessed from the safe zone through a one and a half kilometer underground tunnel. Near the mine at a depth of 150m. a spherical container was placed where hydrogen gas was pumped under high pressure. Heated in the reactor to almost 3000 deg. hydrogen was vented directly into the atmosphere. However, the removal of fission products in this case was close to radioactive emissions from nuclear power plants during their normal operation. And yet, it was not allowed to approach the mine closer than one and a half kilometers during the day, and it was impossible to approach the mine itself for a month. During 13 years of operation, 28 “hot” starts of the IVG-1 reactor were carried out. About 200 gas-cooled fuel assemblies were tested as part of 4 experimental cores. The service life of a number of assemblies accumulated at rated power was 4000 sec. Many of the results of these tests significantly exceed those obtained in the course of work under the NRE program in the USA, so the maximum heat release density in the core of the IVG-1 reactor reached 25 kW/cm3. against 5.2 for the Americans, the temperature of hydrogen at the outlet of the fuel assemblies was about 2800 deg against 2300 for the Americans. In 1977 the second-A workplace of the Baikal bench complex was put into operation, on which, on September 17, 1977. the first bench reactor for YARD 11B91-IR-100 was launched, which received the designation IRGIT. Six months later, March 27, 1978. power start has been carried out. In the course of which a power of 25 MW (15% of the design one) was achieved, the hydrogen temperature was 1500 degrees, the operation time was 70 seconds. During the tests on July 3, 1978. and August 11, 1978. a power of 33 MW was reached and 42 MW, the temperature of hydrogen was 2360 deg. In the late 70s and early 80s, two more series of tests were carried out at the bench complex - the second and third 11B91-IR-100 devices. Testing of fuel assemblies in the IGR and IVG reactors also continued, construction of facilities was underway, with the aim of putting into operation a second-B workplace for testing an engine running on liquid hydrogen. At the same time, tests of the so-called “cold” engine 11B91X, which did not have a nuclear reactor, were carried out at a stand located in Zagorsk near Moscow. Hydrogen was heated in special heat exchangers from ordinary oxygen-hydrogen burners. By 1977 all the tasks of working out a "cold" engine were solved (the units could work for hours). In principle, the YARD was created and preparing it for flight tests was a matter of several more years. YARD 11B91 had a heterogeneous thermal neutron reactor, zirconium hydride served as a moderator, beryllium reflector, nuclear fuel material based on uranium and tungsten carbides, with a uranium-235 content of about 80%. It was a relatively small metal cylinder with a diameter of about 50cm. and about a meter long. Inside - 900 thin rods containing uranium carbide. The YARD reactor was surrounded by a beryllium neutron reflector, into which drums were embedded, coated on one side with a neutron absorber. They played the role of control rods - depending on which side of the drums were facing the core, they absorbed more or less neutrons, regulating the power of the rector (the Americans had the same scheme). Around 1985. YARD 11B91 could make its first space flight. But this did not happen for a variety of reasons. By the beginning of the 1980s, significant progress had been made in the development of highly efficient rocket engines, which, along with the abandonment of plans for the exploration of the Moon and other nearby planets of the solar system, called into question the feasibility of creating a nuclear rocket engine. The economic difficulties that arose and the so-called "Perestroika" led to the fact that the entire space industry was "in disgrace" and in 1988. work on the nuclear rocket engine in the USSR was stopped. The idea of using electricity to create jet propulsion was expressed by K.E. Tsiolkovsky back in 1903. The first experimental EJE was created in the Gas Dynamics Laboratory (Leningrad) under the direction of V.P. Glushko in 1929-1933. The study of the possibility of creating an EJE began at the end of the 50s at the IAE (under the direction of L.A. Artsimovich), NII-1 (under the direction of V.M. Ievlev and A.A. Porotnikov) and a number of other organizations. nizations. So in OKB-1, research was conducted aimed at creating a nuclear electric propulsion engine. In 1962 The preliminary design of the H1 launch vehicle included “Materials on nuclear propulsion for heavy interplanetary spacecraft”. In 1960 A government decree was issued on the organization of work on the electric propulsion system. In addition to the IAE and NII-1, dozens of other research institutes, design bureaus and organizations were involved in the work. By 1962 in NII-1, an erosion-type pulsed plasma thruster (SPT) was created. In SPD, plasma is formed as a result of evaporation (ablation) of a solid dielectric (fluoroplast-4, also known as Teflon) in a pulsed (spark) electric discharge with a duration of several microseconds (pulse power 10–200 MW) followed by electromagnetic acceleration of the plasma. The first life tests of such an engine began on March 27 and continued until April 16, 1962. With an average power consumption of 1 kW (pulsed - 200 MW), the thrust was 1 g. - "price" of thrust 1 kW/g. For tests in space, approximately 4 times less “price” of thrust was required. These parameters were achieved by the end of 1962. The new engine consumed 50 W (pulse power 10 MW) to create a thrust of 0.2g. (later the “price” of traction was increased to 85W for 1 year). In March 1963 A control system for the spacecraft stabilization system based on SPD was created and tested, which included six engines, a voltage converter (a spark discharge was created by capacitors with a capacity of 100 microfarads and a voltage of 1 kV), a program-switching device, high-voltage hermetic connectors, and other equipment. The plasma temperature reached 30 thousand degrees. and the speed of the expiration is 16 km/sec. The first launch of a spacecraft (an interplanetary station of the Zond type) with an electric propulsion engine was scheduled for November 1963. Launch November 11, 1963 ended in an accident RN. November 30, 1964 only. AMS "Zond-2" with EJE on board successfully launched towards Mars. December 14, 1964 at a distance of more than 5 million km from the Earth, plasma engines were switched on (gas-dynamic engines were switched off at that time) operating from solar batteries. Within 70 min. six plasma engines maintained the necessary orientation of the station in space. in the USA in 1968. The communication satellite "LES-6" was launched with four erosion SPDs that functioned for more than 2 years. For further work on the EJE, the Design Bureau "Fakel" was organized (on the basis of the Design Bureau named after B.S. Stechkin, Kaliningrad). The first development of OKB Fakel was the EPS of the stabilization and orientation system for the military spacecraft of the Globus type (AES Horizon), close to the Zond-2 IPD. Since 1971 In the orbit correction system of the Meteor weather satellite, two plasma engines of the Fakel Design Bureau were used, each of which, with a weight of 32.5 kg, consumed about 0.4 kW, while developing a thrust of about 2 g. the exhaust velocity over 8 km/s, the stock of RT (compressed xenon) was 2.4 kg. Since 1982 on geostationary communication satellites "Luch" EJEs developed by OKB "Fakel" are used. Until 1991 ERE successfully operated on 16 spacecraft. More details about the EJD will be described on a separate page of sayia. The thrust of the created EJE was limited by the electric power of the onboard power sources. To increase the thrust of the EPS up to several kilograms, it was necessary to increase the power to several hundred kilowatts, which was practically impossible by traditional methods (batteries and solar panels). Therefore, in parallel with the work on the EJE, the IPPE, IAE, and other organizations launched work on the direct conversion of the thermal energy of a nuclear reactor into electrical energy. The exclusion of intermediate stages of energy conversion and the absence of moving parts made it possible to create compact, lightweight and reliable power plants of sufficiently high power and resource suitable for use on spacecraft. In 1965 In OKB-1, together with the IPPE, a draft design of the nuclear propulsion engine YaERD-2200 for an interplanetary spacecraft with a crew was developed. The propulsion system consisted of two blocks (each had its own nuclear power plant), the electric power of each block was 2200 kW, thrust 8.3 kg. The magnetoplasma engine had a specific impulse of about 54,000 m/s. In 1966-70s. A draft design of a thermionic nuclear power plant (11B97) and an electric propulsion system for the Martian complex launched by the N1M launch vehicle was developed. The nuclear electric propulsion system was assembled from separate blocks; the electric power of one block was up to 5 MW. EJE thrust - 9.5 kg. at a specific thrust impulse of 78000 m/sec. However, the creation of powerful nuclear sources of electricity took much more time than expected. Radioisotope thermoelectric generators (RTGs), which used the heat of spontaneous fission of radioactive isotopes (for example, polonium-210), were the first to find practical application due to their simplicity of design and low weight. The thermoelectric converter was essentially a conventional thermocouple. However, their relatively low power consumption of RITEGs and the high cost of the isotopes used severely limited their application. The use of thermoelectric and thermionic energy converters in combination with nuclear reactors combined into a single unit (reactor-converter) had better prospects. For experimental verification of the possibility of creating a small-sized reactor-converter, in IEA (together with NPO Luch) in 1964. An experimental setup "Romashka" was created. The heat released in the core heated a thermoelectric converter located on the outer surface of the reactor, consisting of a large number of silicon-germanium semiconductor wafers, while their other surface was cooled by a radiator. The electrical power was 500 watts. at a reactor thermal power of 40 kW. The tests of "Chamomile" were soon stopped because it was already undergoing tests of the BES-5 (Buk) nuclear power plant of much higher power. The development of the nuclear power plant BES-5 with an electric power of 2800 W, designed to power the equipment of the US-A radar reconnaissance spacecraft, began in 1961. at NPO Krasnaya Zvezda under the scientific leadership of the IPPE. The first flight of the spacecraft US-A (October 3, 1970 "Cosmos-367") was unsuccessful - the nuclear power plant BES-5 worked for 110 minutes. after which the reactor core melted. The next 9 launches of the modified nuclear power plant were successful in 1975. KA US-A was adopted by the Navy. In January 1978 due to the failure of the US-A spacecraft (Kosmos-954), fragments of the Buk nuclear power plant fell on the territory of Canada. In total (before decommissioning in 1989), these spacecraft were launched 32. - work was carried out on nuclear power plants with thermionic converters that had higher efficiency, service life and weight and size characteristics.In the thermionic nuclear power plant, the effect of thermionic emission from the surface of a sufficiently heated conductor is used. base in Kyiv (in 1970 the same base appeared in Alma-Ata).The work was carried out by two developers - at NPO Krasnaya Zvezda (scientific management of the IPPE), the Topaz nuclear power plant with an electric power of 5-6.6 kW was developed. - cationic reconnaissance, "Energovak-TsKBM" (scientific management of the RRC "Kurchatov Institute") developed the nuclear power plant "Yenisei" for the television broadcasting satellite "Ekran-AM". was tested in space conditions aboard the Plasma-A spacecraft (February 2, 1987. "Cosmos-1818" and July 10, 1987. "Cosmos-1867"). With an estimated resource of one year, already in the second flight, Topaz worked for more than 11 months, but the launches stopped there. Work on the nuclear power plant "Yenisei" was stopped at the stage of ground tests due to the termination of work on the spacecraft for which it was intended. More details about Nuclear power sources for spacecraft will be described on a separate page of the site. In 1970 NPO Energomash developed a draft design of a space nuclear power plant with a gas-phase reactor (with a no-flow zone of fissile material) EU-610 with an electric power of 3.3 GW. However, the problems that arose during the work did not allow the implementation of this project. In 1978 NPO Krasnaya Zvezda developed technical proposals for 2 versions of the Zarya-3 nuclear propulsion system with an electric power of 24 kW and a resource of more than a year. The first option is a modification of the Topaz-1 nuclear power plant, the other had an original scheme (remote TPPs with heat pipes). Work on the installations was terminated due to the lack of binding to a specific spacecraft. In the period 1981-86. a large amount of design and experimental work was carried out, indicating the fundamental possibility of increasing the service life of nuclear power plants up to 3-5 years and electric power up to 600 kW. In 1982 NPO Energia (TsKBEM), according to the terms of reference of the Moscow Region, developed a technical proposal for a nuclear interorbital tug Hercules with an electric power of 550 kW, which is launched into a reference orbit with a height of 200 km. complex "Energy-Buran" or launch vehicle "Proton". In 1986 a technical proposal was developed for the use of an interorbital tug with a nuclear propulsion engine for transporting payloads weighing up to 100 tons into the reference orbit of the Energia launch vehicle into geostationary orbit. But these works were not continued. Thus, a really working nuclear electric propulsion system was never created in the USSR, although nuclear power plants were successfully operated on serial spacecraft. The first and only spacecraft to have a nuclear power plant with an electric propulsion engine was the American Snapshot, launched on April 3, 1965. The electrical power of the reactor-converter was 650 W. An experimental ion engine was installed on the apparatus. However, the very first switching on of the EJE (on the 43rd day of the flight) led to an emergency shutdown of the reactor. Perhaps the reason for this was the high-voltage breakdowns that accompanied the operation of the electric propulsion engine, as a result of which a false command was sent to reset the reactor reflector, which led to its jamming. In 1992 The United States purchased two Yenisei nuclear power plants from Russia. One of the reactors was supposed to be used in 1995. in "Space experiment with a nuclear electric propulsion system". However, in 1996 the project was closed. In the United States, studies on the problem of creating NRE have been carried out at the Los Alamos Laboratory since 1952. In 1957 work began on the Rover program. Unlike the USSR, where element-by-element testing of fuel assemblies and other engine elements was carried out, in the USA they took the path of creating and testing the entire reactor at once. The first reactor named "Kiwi-A" ("KIWI-A") was tested on July 1, 1959. at a special training ground in Nevada. It was a homogeneous reactor whose core was assembled from unprotected plates consisting of a mixture of graphite and uranium-235 oxide enriched up to 90%. Heavy water served as a neutron moderator. Uranium oxide could not withstand high temperatures, and the hydrogen passing through the channels between the plates could only be heated up to 1600 degrees. The power of these reactors was only 100 MW. The Kiwi-A tests, like all subsequent ones, were carried out with an open release. The activity of the exhaust products was low and there were practically no restrictions on work in the test area. The reactor tests were completed on December 7, 1961. (during the last launch, the core was destroyed, the release of fragments of plates into the exhaust jet was noted). The results of six "hot tests" of the nuclear rocket engine turned out to be very encouraging, and at the beginning of 1961. a report was prepared on the need to test the reactor in flight. However, soon the “dizziness” from the first successes began to pass, it was understood that there were many problems on the way to the creation of the YARD, the solution of which would require a lot of time and money. In addition, progress in the creation of chemical engines for combat missiles has left only the space sphere for the use of nuclear rocket engines. Despite the fact that with the advent of the Kennedy administration to the White House (in 1961), work on an aircraft with a nuclear engine was stopped, the Rover program was called “one of the four priorities in the conquest of space” and was further developed. . New programs "Rift" (RIFT - Reactor In Flight Test - a reactor in a test flight) and "Nerva" (NERVA - Nuclear Engine for Rocket Vehicle Application) were adopted to create a flight version of the NRE. Testing of the Kiwi series reactors continued. September 1, 1962 was tested "Kiwi-V" with a capacity of 1100 MW, operating on liquid hydrogen. Uranium oxide was replaced with a more heat-resistant carbide, in addition, the rods were coated with niobium carbide, but during the test, when trying to reach the design temperature, the reactor began to collapse (fragments of the plates began to fly out through the nozzle). The next launch took place on November 30, 1962. but after 260sec. The test was terminated due to strong vibration inside the reactor and flashes of flame in the exhaust jet. As a result of these failures, the planned for 1963. tests of the Kiwi-V reactors were postponed to next year. In August 1964 another test was conducted during which the engine ran at a power of 900 MW for more than eight minutes, developing a thrust of 22.7 tons. at an outflow velocity of 7500 m/s. At the very beginning of 1965. the last test was carried out during which the reactor was destroyed. He was deliberately brought to an explosion as a result of a quick "acceleration". If normally the transition of the reactor from zero power to full power requires tens of seconds, then during this test the duration of such a transition was determined only by the inertia of the control rods, and approximately 44 milliseconds after they were transferred to the full power position, an explosion equivalent to 50–60 kg occurred. trinitrotoluene. The Rift program involved launching a Saturn-V rocket with an experimental reactor along a ballistic trajectory to an altitude of up to 1000 km. and their subsequent fall into the southern part of the Atlantic Ocean. Before entering the water, the YARD reactor was supposed to be blown up (at that time, few people thought about radiation safety). But from year to year, the implementation of the program was delayed and in the end it was never implemented. At the first stage of work on the NERVA engine, they were based on a slightly modified Kiwi-V reactor, called NERVA-NRX (Nuclear Rocket Experimental - experimental nuclear rocket). Since by this time no material had yet been found that could work at 2700–3000 deg. and to resist destruction by hot hydrogen, it was decided to lower the operating temperature and the specific impulse was limited to 8400 m/s. The tests of the reactor began in 1964, they achieved a power of 1000 MW, a thrust of about 22.5 tons. flow velocity over 7000m/s. In 1966 for the first time, the engine was tested at full power of 1100 MW. Where he worked for 28 minutes. (out of 110 minutes of work). The hydrogen temperature at the outlet of the reactor reached 2000 degrees, the thrust was 20 tons. At the next stage of the program, it was supposed to use more powerful Phoebus reactors (Phoebus, and then Pewee). The development of improved solid-phase graphite reactors for the NERVA engine under the Phoebus program has been carried out at the Los Alamos Laboratory since 1963. The first of these reactors has approximately the same dimensions as the Kiwi-V (diameter 0.813 m, length 1.395 m), but is designed for about twice as much power. On the basis of this reactor, it was planned to create the NERVA-1 engine. The next modification with a power of about 4000–5000 MW was to be used for the NERVA-2 engine. This engine has a thrust in the range of 90-110t. was supposed to have an outflow velocity of up to 9000 m/s. The height of the engine is approximately 12m. outer diameter - 1.8m. Consumption of the working fluid 136kg/s. The weight of the NERVA-2 engine was approximately 13.6 tons. due to financial difficulties, the NERVA-2 engine was soon abandoned and they switched to the design of the NERVA-1 engine of increased power with a thrust of 34 tons. flow velocity 8250m/s. The first test of the NRX-A6 reactor for this engine was carried out on December 15, 1967. In June 1969 the first hot tests of the experimental NERVA XE engine with a thrust of 22.7 tons took place. The total engine operation time was 115 minutes, 28 starts were made. YARD "NERVA-1" had a homogeneous reactor with an active zone with a diameter of 1 m. and a height of 1.8m. consisting of 1800 hexagonal fuel rods (the concentration of nuclear fuel is 200 - 700 mg / cc. ). The reactor had an annular reflector about 150 mm thick, made of beryllium oxide. The power vessel of the reactor is made of aluminum alloy, the internal radiation shield is made of composite material (boron carbide–aluminum–titanium hydride). Additional external protection can also be installed between the reactor and turbopump units. NASA considered the engine suitable for a planned mission to Mars. It was supposed to be installed on the upper stage of the Saturn-5 launch vehicle. Such a carrier could carry two or three times more payload into space than its purely chemical version. But most of the American space program was canceled by the Nixon administration. And the termination in 1970. the production of Saturn-5 rockets put an end to the program for the use of nuclear rocket engines. At Los Alamos, work on Pewee engines under the Rover program continued until 1972. after which the program was finally closed. The main difference between our YARDs and American ones is that they were heterogeneous. In homogeneous (homogeneous) reactors, nuclear fuel and moderator are mixed. In the domestic NRE, nuclear fuel was concentrated in fuel elements (separately from the moderator) and was enclosed in a protective shell, so that the moderator operated at much lower temperatures than in American reactors. This made it possible to abandon graphite and use zirconium hydride as a moderator. As a result, the reactor turned out to be much more compact and lighter than the graphite one. This, together with the shape of the rods found by Soviet designers (four-lobed in cross section and twisted in length), made it possible to significantly reduce the loss of uranium as a result of the destruction of the rods (it was not possible to completely eliminate the destruction). At present, only the United States and Russia have significant experience in the development and construction of solid-phase NREs, and, if necessary, will be able to create such engines in a short time and at an acceptable price. The IGR and IVG-1 reactor complexes now belong to the National Nuclear Center of the Republic of Kazakhstan. The equipment is maintained in a relatively operable condition. It is possible that the resumption of work on the programs of flights to the Moon and Mars will revive interest in solid-phase nuclear rocket engines. In addition, the use of NRE can significantly expand the boundaries of the study of the solar system, reducing the time required to reach the distant planets. In 2010 Russian President Medvedev ordered the creation of a space transport and energy module based on a nuclear power plant using ion electric propulsion. The reactor will be built by NIKIET. The Keldysh Center will create a nuclear power plant, and RSC Energia will create the transport and energy module itself. The output electric power of the gas turbine converter in the nominal mode will be 100-150 kW. xenon is supposed to be used as the RT. ERD specific impulse 9000-50000m/sec. resource 1.5-3 years. The mass and dimensions of the installation should allow using the Proton and Angara launch vehicles to launch it. Ground testing of a working prototype will begin in 2014, and by 2017 the nuclear engine will be ready for launch into space (NASA also started a similar program in 2003, but then funding was discontinued). The development of the entire project will require 17 billion rubles. Wait and see.
© Oksana Viktorova/Collage/Ridus
The statement made by Vladimir Putin during his address to the Federal Assembly about the presence in Russia of a nuclear-powered cruise missile caused a great stir in society and the media. At the same time, little was known about what such an engine is and about the possibilities of its use, both for the general public and for specialists.
Reedus tried to figure out what kind of technical device the president could be talking about and what makes it unique.
Considering that the presentation at the Manege was made not for an audience of technical specialists, but for the “general” public, its authors could allow a certain substitution of concepts, Georgy Tikhomirov, deputy director of the Institute of Nuclear Physics and Technology of the National Research Nuclear University MEPhI, does not exclude.
“What the president said and showed, experts call compact power plants, experiments with which were initially carried out in aviation, and then during the exploration of deep space. These were attempts to solve the insoluble problem of sufficient fuel for flights over unlimited distances. In this sense, the presentation is absolutely correct: the presence of such an engine provides energy to the systems of a rocket or any other apparatus for an arbitrarily long time,” he told Reedus.
Work with such an engine in the USSR began exactly 60 years ago under the guidance of academicians M. Keldysh, I. Kurchatov and S. Korolev. In the same years, similar work was carried out in the United States, but was curtailed in 1965. In the USSR, work continued for about a decade before they were also recognized as irrelevant. Perhaps that is why Washington did not wince much, saying that they were not surprised by the presentation of the Russian missile.
In Russia, the idea of a nuclear engine has never died - in particular, since 2009, the practical development of such an installation has been underway. Judging by the timing, the tests announced by the president fit exactly into this joint project of Roscosmos and Rosatom, since the developers planned to conduct field tests of the engine in 2018. Perhaps, due to political reasons, they pulled themselves up a little and shifted the deadlines “to the left”.
“Technologically, it is arranged in such a way that the nuclear power unit heats the gas coolant. And this heated gas either rotates the turbine or creates jet thrust directly. A certain cunning in the presentation of the rocket, which we heard, is that the range of its flight is still not infinite: it is limited by the volume of the working fluid - liquid gas, which can physically be pumped into the rocket tanks, ”says the specialist.
At the same time, a space rocket and a cruise missile have fundamentally different flight control schemes, since they have different tasks. The first one flies in airless space, it does not need to maneuver - it is enough to give it an initial impulse, and then it moves along the calculated ballistic trajectory.
A cruise missile, on the contrary, must continuously change its trajectory, for which it must have enough fuel to create impulses. Whether this fuel will be ignited by a nuclear power plant or a traditional one is not important in this case. Only the supply of this fuel is important, Tikhomirov emphasizes.
“The meaning of a nuclear installation during flights into deep space is the presence of an energy source on board to power the systems of the apparatus for an unlimited time. In this case, there can be not only a nuclear reactor, but also radioisotope thermoelectric generators. And the meaning of such an installation on a rocket, the flight of which will not last longer than a few tens of minutes, is not yet completely clear to me, ”the physicist admits.
The report at the Manege was only a couple of weeks late compared to NASA's February 15 announcement that the Americans were resuming nuclear rocket propulsion research that they abandoned half a century ago.
By the way, in November 2017, the China Aerospace Science and Technology Corporation (CASC) already announced that before 2045, a nuclear-powered spacecraft would be created in China. Therefore, today we can safely say that the world nuclear propulsion race has begun.
Beware of many letters.
A flight model of a spacecraft with a nuclear power plant (NPP) in Russia is planned to be created by 2025. The relevant work is included in the draft Federal Space Program for 2016–2025 (FKP-25), which was sent by Roscosmos to the ministries for approval.
Nuclear power systems are considered the main promising sources of energy in space when planning large-scale interplanetary expeditions. In the future, nuclear power plants, which are currently being developed by Rosatom enterprises, will be able to provide megawatt power in space in the future.
All work on the creation of nuclear power plants is proceeding in accordance with the planned deadlines. We can say with a great deal of confidence that the work will be completed within the time frame stipulated by the target program, - says Andrey Ivanov, project manager of the communications department of the state corporation Rosatom.
Recently, two important stages have been passed within the framework of the project: a unique design of the fuel element has been created, which ensures operability at high temperatures, large temperature gradients, and high-dose irradiation. Technological tests of the reactor vessel of the future space power unit have also been successfully completed. As part of these tests, the body was pressurized and 3D measurements were made in the areas of the base metal, girth weld and cone transition.
Operating principle. History of creation.
There are no fundamental difficulties with a nuclear reactor for space use. In the period from 1962 to 1993, a rich experience in the production of similar installations was accumulated in our country. Similar work was carried out in the USA. Since the beginning of the 1960s, several types of electric jet engines have been developed in the world: ion, stationary plasma, an anode layer engine, pulsed plasma engine, magnetoplasma, magnetoplasmodynamic.
Work on the creation of nuclear engines for spacecraft was actively carried out in the USSR and the USA in the last century: the Americans closed the project in 1994, the USSR - in 1988. The closure of work was largely facilitated by the Chernobyl disaster, which negatively tuned public opinion regarding the use of nuclear energy. In addition, tests of nuclear installations in space did not always take place regularly: in 1978, the Soviet satellite Kosmos-954 entered the atmosphere and fell apart, scattering thousands of radioactive fragments over an area of 100 thousand square meters. km in northwestern Canada. The Soviet Union paid Canada monetary compensation in the amount of more than $10 million.
In May 1988, two organizations - the Federation of American Scientists and the Committee of Soviet Scientists for Peace Against the Nuclear Threat - made a joint proposal to ban the use of nuclear energy in space. That proposal did not receive formal consequences, but since then no country has launched spacecraft with nuclear power plants on board.
The great advantages of the project are practically important performance characteristics - a long service life (10 years of operation), a significant overhaul interval and a long time of operation on one switch.
In 2010, technical proposals for the project were formulated. Design began this year.
The nuclear power plant contains three main devices: 1) a reactor plant with a working fluid and auxiliary devices (a heat exchanger-recuperator and a turbogenerator-compressor); 2) electric rocket propulsion system; 3) refrigerator-emitter.
Reactor.
From a physical point of view, this is a compact gas-cooled fast neutron reactor.
The fuel used is a compound (dioxide or carbonitride) of uranium, but because the design must be very compact, uranium has a higher enrichment in the 235 isotope than in fuel rods in conventional (civilian) nuclear power plants, perhaps over 20%. And their shell is a monocrystalline alloy of refractory metals based on molybdenum.
This fuel will have to work at very high temperatures. Therefore, it was necessary to choose materials that would be able to restrain the negative factors associated with temperature, and at the same time allow the fuel to perform its main function - to heat the gas coolant, which will be used to produce electricity.
Fridge.
Gas cooling during the operation of a nuclear installation is absolutely necessary. How to dump heat in outer space? The only possibility is radiation cooling. The heated surface in the void is cooled by emitting electromagnetic waves in a wide range, including visible light. The uniqueness of the project is in the use of a special coolant - helium-xenon mixture. The installation provides a high efficiency.
Engine.
The principle of operation of the ion engine is as follows. A rarefied plasma is created in the gas-discharge chamber with the help of anodes and a cathode block located in a magnetic field. Ions of the working fluid (xenon or other substance) are "drawn" from it by the emission electrode and accelerated in the gap between it and the accelerating electrode.
For the implementation of the plan, 17 billion rubles were promised in the period from 2010 to 2018. Of these funds, 7.245 billion rubles were earmarked for the state corporation Rosatom to build the reactor itself. Other 3.955 billion - FSUE "Center of Keldysh" for the creation of a nuclear - power propulsion plant. Another 5.8 billion rubles will go to RSC Energia, where the working image of the entire transport and energy module will have to be formed within the same time frame.
According to plans, by the end of 2017, a nuclear power plant will be prepared to complete the transport and energy module (interplanetary flight module). By the end of 2018, the nuclear power plant will be ready for flight design tests. The project is financed from the federal budget.
It is no secret that work on the creation of nuclear rocket engines was started in the USA and in the USSR back in the 60s of the last century. How far have they come? And what challenges did you encounter along the way?
Anatoly Koroteev: Indeed, work on the use of nuclear energy in space began and was actively carried out in our country and in the United States in the 1960s and 70s.
Initially, the task was to create rocket engines that would use hydrogen heating to a temperature of about 3000 degrees instead of the chemical energy of fuel and oxidizer combustion. But it turned out that such a direct path is still inefficient. We get high thrust for a short time, but at the same time we throw out a jet, which, in the event of abnormal operation of the reactor, may turn out to be radioactively contaminated.
Some experience was gained, but neither we nor the Americans were able to create reliable engines then. They worked, but not enough, because heating hydrogen to 3000 degrees in a nuclear reactor is a serious task. And besides, there were environmental problems during ground tests of such engines, since radioactive jets were emitted into the atmosphere. It is no longer a secret that such work was carried out at the Semipalatinsk test site specially prepared for nuclear testing, which remained in Kazakhstan.
That is, two parameters turned out to be critical - prohibitive temperature and radiation emissions?
Anatoly Koroteev: In general, yes. For these and some other reasons, work in our country and in the United States was terminated or suspended - it can be assessed in different ways. And it seemed to us unreasonable to resume them in such a way, I would say, in a frontal way, in order to make a nuclear engine with all the shortcomings already mentioned. We have proposed a completely different approach. It differs from the old one in the same way that a hybrid car differs from a conventional one. In a conventional car, the engine turns the wheels, while in hybrid cars, electricity is generated from the engine, and this electricity turns the wheels. That is, a certain intermediate power plant is being created.
So we proposed a scheme in which the space reactor does not heat the jet ejected from it, but generates electricity. The hot gas from the reactor turns the turbine, the turbine turns the electric generator and the compressor, which circulates the working fluid in a closed circuit. The generator, on the other hand, generates electricity for a plasma engine with a specific thrust 20 times higher than that of chemical counterparts.
Smart scheme. In essence, this is a mini-nuclear power plant in space. And what are its advantages over a ramjet nuclear engine?
Anatoly Koroteev: The main thing is that the jet coming out of the new engine will not be radioactive, since a completely different working fluid passes through the reactor, which is contained in a closed circuit.
In addition, we do not need to heat hydrogen to extreme values with this scheme: an inert working fluid circulates in the reactor, which heats up to 1500 degrees. We seriously simplify our task. And as a result, we will raise the specific thrust not twice, but 20 times compared to chemical engines.
Another thing is also important: there is no need for complex full-scale tests, which require the infrastructure of the former Semipalatinsk test site, in particular, the bench base that remained in the city of Kurchatov.
In our case, all the necessary tests can be carried out on the territory of Russia, without getting involved in long international negotiations on the use of nuclear energy outside of our state.
Are similar works being carried out in other countries?
Anatoly Koroteev: I had a meeting with the deputy head of NASA, we discussed issues related to the return to work on nuclear energy in space, and he said that the Americans are showing great interest in this.
It is quite possible that China can also respond with active actions on its part, so it is necessary to work quickly. And not just for the sake of getting ahead of someone by half a step.
We must work quickly, first of all, so that in the emerging international cooperation, and de facto it is being formed, we look worthy.
I do not rule out that in the near future an international program for a nuclear space power plant, similar to the program for controlled thermonuclear fusion being implemented now, may be initiated.
Liquid rocket engines made it possible for man to go into space - into near-Earth orbits. But the speed of the jet stream in the LRE does not exceed 4.5 km / s, and for flights to other planets, tens of kilometers per second are needed. A possible way out is to use the energy of nuclear reactions.
The practical creation of nuclear rocket engines (NRE) was carried out only by the USSR and the USA. In 1955, the United States began implementing the Rover program to develop a nuclear rocket engine for spacecraft. Three years later, in 1958, the project was taken over by NASA, which set a specific task for ships with YARD - a flight to the Moon and Mars. Since that time, the program has become known as NERVA, which stands for "nuclear engine for installation on rockets."
By the mid-1970s, within the framework of this program, it was planned to design a nuclear rocket engine with a thrust of about 30 tons (for comparison, the characteristic thrust of an LRE of that time was about 700 tons), but with a gas exhaust velocity of 8.1 km / s. However, in 1973, the program was closed due to the shift in US interests towards the space shuttle.
In the USSR, the design of the first NRE was carried out in the second half of the 50s. At the same time, Soviet designers, instead of creating a full-scale model, began to make separate parts of the YARD. And then these developments were tested in cooperation with a specially designed pulsed graphite reactor (IGR).
In the 70-80s of the last century, the Salyut Design Bureau, the Khimavtomatika Design Bureau and the Luch Research and Production Association created projects for space nuclear rocket engines RD-0411 and RD-0410 with a thrust of 40 and 3.6 tons, respectively. During the design process, a reactor, a "cold" engine and a bench prototype were manufactured for testing.
In July 1961, Soviet academician Andrei Sakharov announced the project for a nuclear explosion at a meeting of leading atomic scientists in the Kremlin. The explosive had conventional liquid-propellant rocket engines for take-off, while in space it was supposed to explode small nuclear charges. The fission products generated during the explosion transferred their momentum to the ship, causing it to fly. However, on August 5, 1963, an agreement was signed in Moscow banning nuclear weapons tests in the atmosphere, outer space and under water. This was the reason for the closure of the nuclear explosive program.
It is possible that the development of the YARD was ahead of its time. However, they were not too premature. After all, the preparation of a manned flight to other planets takes several decades, and the propulsion systems for it must be prepared in advance.
Design of a nuclear rocket engine
A nuclear rocket engine (NRE) is a jet engine in which the energy generated by a nuclear decay or fusion reaction heats the working fluid (most often hydrogen or ammonia).
There are three types of NRE according to the type of fuel for the reactor:
- solid phase;
- liquid-phase;
- gas phase.
The most complete is solid phase engine option. The figure shows a diagram of the simplest NRE with a solid nuclear fuel reactor. The working fluid is located in an external tank. With the help of a pump, it is fed into the engine chamber. In the chamber, the working fluid is sprayed with the help of nozzles and comes into contact with the heat-generating nuclear fuel. When heated, it expands and flies out of the chamber through a nozzle at great speed.
liquid phase- nuclear fuel in the reactor core of such an engine is in liquid form. The traction parameters of such engines are higher than those of solid-phase ones, due to the higher temperature of the reactor.
AT gas-phase NRE fuel (for example, uranium) and the working fluid is in a gaseous state (in the form of plasma) and is held in the working area by an electromagnetic field. Heated to tens of thousands of degrees, uranium plasma transfers heat to the working fluid (for example, hydrogen), which, in turn, being heated to high temperatures, forms a jet.
According to the type of nuclear reaction, a radioisotope rocket engine, a thermonuclear rocket engine, and a nuclear engine proper (the energy of nuclear fission is used) are distinguished.
An interesting option is also a pulsed NRE - it is proposed to use a nuclear charge as an energy source (fuel). Such installations can be of internal and external types.
The main advantages of the YRD are:
- high specific impulse;
- significant energy reserve;
- compactness of the propulsion system;
- the possibility of obtaining very large thrust - tens, hundreds and thousands of tons in a vacuum.
The main disadvantage is the high radiation hazard of the propulsion system:
- fluxes of penetrating radiation (gamma radiation, neutrons) during nuclear reactions;
- removal of highly radioactive compounds of uranium and its alloys;
- outflow of radioactive gases with the working fluid.
Therefore, the launch of a nuclear engine is unacceptable for launches from the Earth's surface due to the risk of radioactive contamination.
- Green tomatoes stuffed for the winter - a delicious snack
- Tomatoes for the winter stuffed with garlic and herbs
- Grissini - Proven Italian Breadstick Recipes
- Raf coffee: the history of creation and options for preparing a coffee drink
- Quick snacks
- Useful culinary tricks for housewives
- Vegetarian mayonnaise at home
- Apple Pie - A Quick Recipe
- Secrets of cooking Tatar sweets chak-chak
- Improving the range and increasing the nutritional value of bread and bakery products
- Features and recipes for onion confiture and jam
- What kind of fish can be salted at home: choices and cooking tips Salt white fish
- What is yantra, types of yantra meaning
- wood burning technology
- How to calculate the specific gravity in different areas?
- Geography of beef cattle breeding (cattle, pigs, sheep), poultry farming
- Analysis of the company's market share is an effective tool for a successful business What share in sales is considered the norm
- The seventh technological mode is cognitive
- Types of one-part sentences
- The concept of dialect. What is a dialect? Grammar Dictionary: Grammar and linguistic terms