Nuclear and plasma rocket engines. Nuclear power plant for missiles and underwater vehicles The principle of operation of a nuclear engine
Sergeev Alexey, 9 “A” class, Municipal Educational Institution “Secondary School No. 84”
Scientific consultant: , Deputy Director of the non-profit partnership for scientific and innovative activities "Tomsk Atomic Center"
Head: , physics teacher, Municipal Educational Institution “Secondary School No. 84” CATO Seversk
Introduction
Propulsion systems on board a spacecraft are designed to create thrust or momentum. According to the type of thrust used, the propulsion system is divided into chemical (CHRD) and non-chemical (NCRD). CRDs are divided into liquid propellant engines (LPRE), solid propellant rocket engines (solid propellant engines) and combined rocket engines (RCR). In turn, non-chemical propulsion systems are divided into nuclear (NRE) and electric (EP). The great scientist Konstantin Eduardovich Tsiolkovsky a century ago created the first model of a propulsion system that ran on solid and liquid fuel. Afterwards, in the second half of the 20th century, thousands of flights were carried out using mainly liquid propellant engines and solid propellant rocket engines.
However, at present, for flights to other planets, not to mention the stars, the use of liquid propellant rocket engines and solid propellant rocket engines is becoming increasingly unprofitable, although many rocket engines have been developed. Most likely, the capabilities of liquid propellant rocket engines and solid propellant rocket engines have completely exhausted themselves. The reason here is that the specific impulse of all chemical thrusters is low and does not exceed 5000 m/s, which requires long-term operation of the thruster and, accordingly, large reserves of fuel for the development of sufficiently high speeds, or, as is customary in astronautics, large values of the Tsiolkovsky number are required, t i.e. the ratio of the mass of a fueled rocket to the mass of an empty one. Thus, the Energia launch vehicle, which launches 100 tons of payload into low orbit, has a launch mass of about 3,000 tons, which gives the Tsiolkovsky number a value within 30.
For a flight to Mars, for example, the Tsiolkovsky number should be even higher, reaching values from 30 to 50. It is easy to estimate that with a payload of about 1,000 tons, and it is within these limits that the minimum mass required to provide everything necessary for the crew starting to Mars varies Taking into account the fuel supply for the return flight to Earth, the initial mass of the spacecraft must be at least 30,000 tons, which is clearly beyond the level of development of modern astronautics, based on the use of liquid propellant engines and solid propellant rocket engines.
Thus, in order for manned crews to reach even the nearest planets, it is necessary to develop launch vehicles on engines operating on principles other than chemical propulsion. The most promising in this regard are electric jet engines (EPE), thermochemical rocket engines and nuclear jet engines (NRE).
1.Basic concepts
A rocket engine is a jet engine that does not use the environment (air, water) for operation. Chemical rocket engines are the most widely used. Other types of rocket engines are being developed and tested - electric, nuclear and others. The simplest rocket engines running on compressed gases are also widely used on space stations and vehicles. Typically, they use nitrogen as a working fluid. /1/
Classification of propulsion systems
2. Purpose of rocket engines
According to their purpose, rocket engines are divided into several main types: accelerating (starting), braking, propulsion, control and others. Rocket engines are primarily used on rockets (hence the name). In addition, rocket engines are sometimes used in aviation. Rocket engines are the main engines in astronautics.
Military (combat) missiles usually have solid propellant motors. This is due to the fact that such an engine is refueled at the factory and does not require maintenance for the entire storage and service life of the rocket itself. Solid propellant engines are often used as boosters for space rockets. They are used especially widely in this capacity in the USA, France, Japan and China.
Liquid rocket engines have higher thrust characteristics than solid rocket engines. Therefore, they are used to launch space rockets into orbit around the Earth and for interplanetary flights. The main liquid propellants for rockets are kerosene, heptane (dimethylhydrazine) and liquid hydrogen. For such types of fuel, an oxidizer (oxygen) is required. Nitric acid and liquefied oxygen are used as oxidizers in such engines. Nitric acid is inferior to liquefied oxygen in terms of oxidizing properties, but does not require maintaining a special temperature regime during storage, refueling and use of missiles
Engines for space flights differ from those on Earth in that they must produce as much power as possible with the smallest possible mass and volume. In addition, they are subject to such requirements as exceptionally high efficiency and reliability, and significant operating time. Based on the type of energy used, spacecraft propulsion systems are divided into four types: thermochemical, nuclear, electric, solar-sail. Each of the listed types has its own advantages and disadvantages and can be used in certain conditions.
Currently, spaceships, orbital stations and unmanned Earth satellites are launched into space by rockets equipped with powerful thermochemical engines. There are also miniature engines with low thrust. This is a smaller copy of powerful engines. Some of them can fit in the palm of your hand. The thrust force of such engines is very small, but it is enough to control the position of the ship in space
3.Thermochemical rocket engines.
It is known that in an internal combustion engine, the furnace of a steam boiler - wherever combustion occurs, atmospheric oxygen takes the most active part. There is no air in outer space, and for rocket engines to operate in outer space, it is necessary to have two components - fuel and oxidizer.
Liquid thermochemical rocket engines use alcohol, kerosene, gasoline, aniline, hydrazine, dimethylhydrazine, and liquid hydrogen as fuel. Liquid oxygen, hydrogen peroxide, and nitric acid are used as an oxidizing agent. Perhaps in the future liquid fluorine will be used as an oxidizing agent when methods for storing and using such an active chemical are invented
Fuel and oxidizer for liquid jet engines are stored separately in special tanks and supplied to the combustion chamber using pumps. When they are combined in the combustion chamber, temperatures reach 3000 – 4500 °C.
Combustion products, expanding, acquire speeds from 2500 to 4500 m/s. Pushing off from the engine body, they create jet thrust. At the same time, the greater the mass and speed of gas flow, the greater the thrust of the engine.
The specific thrust of engines is usually estimated by the amount of thrust created per unit mass of fuel burned in one second. This quantity is called the specific impulse of a rocket engine and is measured in seconds (kg thrust / kg burnt fuel per second). The best solid propellant rocket engines have a specific impulse of up to 190 s, that is, 1 kg of fuel burning in one second creates a thrust of 190 kg. A hydrogen-oxygen rocket engine has a specific impulse of 350 s. Theoretically, a hydrogen-fluorine engine can develop a specific impulse of more than 400 s.
The commonly used liquid rocket engine circuit works as follows. Compressed gas creates the necessary pressure in tanks with cryogenic fuel to prevent the occurrence of gas bubbles in pipelines. Pumps supply fuel to rocket engines. Fuel is injected into the combustion chamber through a large number of injectors. An oxidizer is also injected into the combustion chamber through the nozzles.
In any car, when fuel burns, large heat flows are formed that heat the walls of the engine. If you do not cool the walls of the chamber, it will quickly burn out, no matter what material it is made of. A liquid jet engine is typically cooled by one of the fuel components. For this purpose, the chamber is made of two walls. The cold component of the fuel flows in the gap between the walls.
Aluminum" href="/text/category/alyuminij/" rel="bookmark">aluminum, etc. Especially as an additive to conventional fuels, such as hydrogen-oxygen. Such “ternary compositions” can provide the highest speed possible for chemical fuels exhaust - up to 5 km/s. But this is practically the limit of the resources of chemistry. It practically cannot do more. Although the proposed description is still dominated by liquid rocket engines, it must be said that the first in the history of mankind was created a thermochemical rocket engine using solid fuel - Solid propellant rocket motor. Fuel - for example, special gunpowder - is located directly in the combustion chamber. A combustion chamber with a jet nozzle filled with solid fuel - that’s the whole design. The combustion mode of solid fuel depends on the purpose of the solid propellant rocket engine (launch, sustainer or combined). For solid fuel rockets used in military affairs are characterized by the presence of launch and propulsion engines.The launch solid propellant rocket engine develops high thrust for a very short time, which is necessary for the missile to leave the launcher and for its initial acceleration. The sustainer solid propellant rocket motor is designed to maintain a constant flight speed of the rocket on the main (propulsion) section of the flight path. The differences between them lie mainly in the design of the combustion chamber and the profile of the combustion surface of the fuel charge, which determine the rate of fuel combustion on which the operating time and engine thrust depend. Unlike such rockets, space launch vehicles for launching Earth satellites, orbital stations and spacecraft, as well as interplanetary stations operate only in the launch mode from the launch of the rocket until the object is launched into orbit around the Earth or onto an interplanetary trajectory. In general, solid propellant rocket engines do not have many advantages over liquid fuel engines: they are easy to manufacture, can be stored for a long time, are always ready for action, and are relatively explosion-proof. But in terms of specific thrust, solid fuel engines are 10-30% inferior to liquid engines.
4. Electric rocket engines
Almost all of the rocket engines discussed above develop enormous thrust and are designed to launch spacecraft into orbit around the Earth and accelerate them to cosmic speeds for interplanetary flights. A completely different matter is propulsion systems for spacecraft already launched into orbit or on an interplanetary trajectory. Here, as a rule, we need low-power motors (several kilowatts or even watts) capable of operating for hundreds and thousands of hours and being switched on and off repeatedly. They allow you to maintain flight in orbit or along a given trajectory, compensating for the flight resistance created by the upper layers of the atmosphere and the solar wind. In electric rocket engines, the working fluid is accelerated to a certain speed by heating it with electrical energy. Electricity comes from solar panels or a nuclear power plant. Methods for heating the working fluid are different, but in reality, electric arc is mainly used. It has proven to be very reliable and can withstand a large number of starts. Hydrogen is used as a working fluid in electric arc motors. Using an electric arc, hydrogen is heated to a very high temperature and it turns into plasma - an electrically neutral mixture of positive ions and electrons. The speed of plasma outflow from the engine reaches 20 km/s. When scientists solve the problem of magnetic isolation of plasma from the walls of the engine chamber, then it will be possible to significantly increase the temperature of the plasma and increase the exhaust speed to 100 km/s. The first electric rocket engine was developed in the Soviet Union in the years. under the leadership (later he became the creator of engines for Soviet space rockets and an academician) at the famous Gas Dynamics Laboratory (GDL)./10/
5.Other types of engines
There are also more exotic designs for nuclear rocket engines, in which the fissile material is in a liquid, gaseous or even plasma state, but the implementation of such designs at the current level of technology and technology is unrealistic. The following rocket engine projects exist, still at the theoretical or laboratory stage:
Pulse nuclear rocket engines using the energy of explosions of small nuclear charges;
Thermonuclear rocket engines, which can use a hydrogen isotope as fuel. The energy productivity of hydrogen in such a reaction is 6.8 * 1011 KJ/kg, that is, approximately two orders of magnitude higher than the productivity of nuclear fission reactions;
Solar-sail engines - which use the pressure of sunlight (solar wind), the existence of which was empirically proven by a Russian physicist back in 1899. By calculation, scientists have established that a device weighing 1 ton, equipped with a sail with a diameter of 500 m, can fly from Earth to Mars in about 300 days. However, the efficiency of a solar sail decreases rapidly with distance from the Sun.
6.Nuclear rocket engines
One of the main disadvantages of rocket engines running on liquid fuel is associated with the limited flow rate of gases. In nuclear rocket engines, it seems possible to use the colossal energy released during the decomposition of nuclear “fuel” to heat the working substance. The operating principle of nuclear rocket engines is almost no different from the operating principle of thermochemical engines. The difference is that the working fluid is heated not due to its own chemical energy, but due to “extraneous” energy released during an intranuclear reaction. The working fluid is passed through a nuclear reactor, in which the fission reaction of atomic nuclei (for example, uranium) occurs, and is heated. Nuclear rocket engines eliminate the need for an oxidizer and therefore only one liquid can be used. As a working fluid, it is advisable to use substances that allow the engine to develop greater traction force. This condition is most fully satisfied by hydrogen, followed by ammonia, hydrazine and water. The processes in which nuclear energy is released are divided into radioactive transformations, fission reactions of heavy nuclei, and fusion reactions of light nuclei. Radioisotope transformations are realized in so-called isotope energy sources. The specific mass energy (the energy that a substance weighing 1 kg can release) of artificial radioactive isotopes is significantly higher than that of chemical fuels. Thus, for 210Po it is equal to 5*10 8 KJ/kg, while for the most energy-efficient chemical fuel (beryllium with oxygen) this value does not exceed 3*10 4 KJ/kg. Unfortunately, it is not yet rational to use such engines on space launch vehicles. The reason for this is the high cost of the isotopic substance and operational difficulties. After all, the isotope constantly releases energy, even when it is transported in a special container and when the rocket is parked at the launch site. Nuclear reactors use more energy-efficient fuel. Thus, the specific mass energy of 235U (the fissile isotope of uranium) is equal to 6.75 * 10 9 KJ/kg, that is, approximately an order of magnitude higher than that of the 210Po isotope. These engines can be “switched on” and “switched off”; nuclear fuel (233U, 235U, 238U, 239Pu) is much cheaper than isotope fuel. In such engines, not only water can be used as a working fluid, but also more efficient working substances - alcohol, ammonia, liquid hydrogen. The specific thrust of an engine with liquid hydrogen is 900 s. In the simplest design of a nuclear rocket engine with a reactor running on solid nuclear fuel, the working fluid is placed in a tank. The pump supplies it to the engine chamber. Sprayed using nozzles, the working fluid comes into contact with the fuel-generating nuclear fuel, heats up, expands and is thrown out at high speed through the nozzle. Nuclear fuel is superior in energy reserves to any other type of fuel. Then a logical question arises: why do installations using this fuel still have a relatively low specific thrust and a large mass? The fact is that the specific thrust of a solid-phase nuclear rocket engine is limited by the temperature of the fissile material, and the power plant during operation emits strong ionizing radiation, which has a harmful effect on living organisms. Biological protection against such radiation is very important and is not applicable on spacecraft. Practical development of nuclear rocket engines using solid nuclear fuel began in the mid-50s of the 20th century in the Soviet Union and the USA, almost simultaneously with the construction of the first nuclear power plants. The work was carried out in an atmosphere of increased secrecy, but it is known that such rocket engines have not yet received real use in astronautics. Everything has so far been limited to the use of isotopic sources of electricity of relatively low power on unmanned artificial Earth satellites, interplanetary spacecraft and the world famous Soviet “lunar rover”.
7.Nuclear jet engines, operating principles, methods of obtaining impulse in a nuclear propulsion engine.
Nuclear rocket engines got their name due to the fact that they create thrust through the use of nuclear energy, that is, the energy that is released as a result of nuclear reactions. In a general sense, these reactions mean any changes in the energy state of atomic nuclei, as well as transformations of some nuclei into others, associated with a restructuring of the structure of nuclei or a change in the number of elementary particles contained in them - nucleons. Moreover, nuclear reactions, as is known, can occur either spontaneously (i.e. spontaneously) or caused artificially, for example, when some nuclei are bombarded by others (or elementary particles). Nuclear fission and fusion reactions exceed chemical reactions by millions and tens of millions of times in energy, respectively. This is explained by the fact that the chemical bond energy of atoms in molecules is many times less than the nuclear bond energy of nucleons in the nucleus. Nuclear energy in rocket engines can be used in two ways:
1. The released energy is used to heat the working fluid, which then expands in the nozzle, just like in a conventional rocket engine.
2. Nuclear energy is converted into electrical energy and then used to ionize and accelerate particles of the working fluid.
3. Finally, the impulse is created by the fission products themselves, formed in the process DIV_ADBLOCK265">
By analogy with a liquid-propellant rocket engine, the initial working fluid of the nuclear-propulsion engine is stored in a liquid state in the tank of the propulsion system and is supplied using a turbopump unit. The gas for rotating this unit, consisting of a turbine and a pump, can be produced in the reactor itself.
A diagram of such a propulsion system is shown in the figure.
There are many nuclear powered engines with a fission reactor:
Solid phase
Gas phase
NRE with fusion reactor
Pulse nuclear propulsion engines and others
Of all the possible types of nuclear propulsion engines, the most developed are the thermal radioisotope engine and the engine with a solid-phase fission reactor. But if the characteristics of radioisotope nuclear propulsion engines do not allow us to hope for their widespread use in astronautics (at least in the near future), then the creation of solid-phase nuclear propulsion engines opens up great prospects for astronautics. A typical nuclear propulsion engine of this type contains a solid-phase reactor in the form of a cylinder with a height and diameter of about 1-2 m (if these parameters are close, the leakage of fission neutrons into the surrounding space is minimal).
The reactor consists of a core; a reflector surrounding this area; governing bodies; power body and other elements. The core contains nuclear fuel - fissile material (enriched uranium) contained in fuel elements, and a moderator or diluent. The reactor shown in the figure is homogeneous - in it the moderator is part of the fuel elements, being homogeneously mixed with the fuel. The moderator can also be located separately from the nuclear fuel. In this case, the reactor is called heterogeneous. Diluents (they can be, for example, refractory metals - tungsten, molybdenum) are used to impart special properties to fissile substances.
The fuel elements of a solid-phase reactor are permeated with channels through which the working fluid of the nuclear propulsion engine flows, gradually heating up. The channels have a diameter of about 1-3 mm, and their total area is 20-30% of the cross-section of the active zone. The core is suspended by a special grid inside the power vessel so that it can expand when the reactor heats up (otherwise it would collapse due to thermal stresses).
The core experiences high mechanical loads associated with significant hydraulic pressure drops (up to several tens of atmospheres) from the flowing working fluid, thermal stresses and vibrations. The increase in the size of the active zone when the reactor heats up reaches several centimeters. The active zone and reflector are placed inside a durable power housing that absorbs the pressure of the working fluid and the thrust created by the jet nozzle. The case is closed with a durable lid. It houses pneumatic, spring or electric mechanisms for driving the regulatory bodies, attachment points for the nuclear propulsion engine to the spacecraft, and flanges for connecting the nuclear propulsion engine to the supply pipelines of the working fluid. A turbopump unit can also be located on the cover.
8 - Nozzle,
9 - Expanding nozzle nozzle,
10 - Selection of working substance for the turbine,
11 - Power Corps,
12 - Control drum,
13 - Turbine exhaust (used to control attitude and increase thrust),
14 - Drive ring for control drums)
At the beginning of 1957, the final direction of work at the Los Alamos Laboratory was determined, and a decision was made to build a graphite nuclear reactor with uranium fuel dispersed in graphite. The Kiwi-A reactor, created in this direction, was tested in 1959 on July 1st.
American solid phase nuclear jet engine XE Prime on a test bench (1968)
In addition to the construction of the reactor, the Los Alamos Laboratory was in full swing on the construction of a special test site in Nevada, and also carried out a number of special orders from the US Air Force in related areas (the development of individual TURE units). On behalf of the Los Alamos Laboratory, all special orders for the manufacture of individual components were carried out by the following companies: Aerojet General, the Rocketdyne division of North American Aviation. In the summer of 1958, all control of the Rover program was transferred from the United States Air Force to the newly organized National Aeronautics and Space Administration (NASA). As a result of a special agreement between the AEC and NASA in the mid-summer of 1960, the Space Nuclear Propulsion Office was formed under the leadership of G. Finger, which subsequently headed the Rover program.
The results obtained from six "hot tests" of nuclear jet engines were very encouraging, and in early 1961 a report on reactor flight testing (RJFT) was prepared. Then, in mid-1961, the Nerva project (the use of a nuclear engine for space rockets) was launched. Aerojet General was chosen as the general contractor, and Westinghouse was chosen as the subcontractor responsible for the construction of the reactor.
10.2 Work on TURE in Russia
American" href="/text/category/amerikanetc/" rel="bookmark">Americans, Russian scientists used the most economical and effective tests of individual fuel elements in research reactors. The entire range of work carried out in the 70-80s allowed the design bureau " Salyut", Design Bureau of Chemical Automatics, IAE, NIKIET and NPO "Luch" (PNITI) to develop various projects of space nuclear propulsion engines and hybrid nuclear power plants. In the Design Bureau of Chemical Automatics under the scientific leadership of NIITP (FEI, IAE, NIKIET, NIITVEL, NPO were responsible for the reactor elements Luch", MAI) were created YARD RD 0411 and nuclear engine of minimum size RD 0410 thrust 40 and 3.6 tons, respectively.
As a result, a reactor, a “cold” engine and a bench prototype were manufactured for testing on hydrogen gas. Unlike the American one, with a specific impulse of no more than 8250 m/s, the Soviet TNRE, due to the use of more heat-resistant and advanced design fuel elements and high temperature in the core, had this figure equal to 9100 m/s and higher. The bench base for testing the TURE of the joint expedition of NPO "Luch" was located 50 km southwest of the city of Semipalatinsk-21. She started working in 1962. In At the test site, full-scale fuel elements of nuclear-powered rocket engine prototypes were tested. In this case, the exhaust gas entered the closed exhaust system. The Baikal-1 test bench complex for full-size nuclear engine testing is located 65 km south of Semipalatinsk-21. From 1970 to 1988, about 30 “hot starts” of reactors were carried out. At the same time, the power did not exceed 230 MW with a hydrogen consumption of up to 16.5 kg/sec and its temperature at the reactor outlet of 3100 K. All launches were successful, trouble-free, and according to plan.
Soviet TNRD RD-0410 is the only working and reliable industrial nuclear rocket engine in the world
Currently, such work at the site has been stopped, although the equipment is maintained in relatively working condition. The test bench base of NPO Luch is the only experimental complex in the world where it is possible to test elements of nuclear propulsion reactors without significant financial and time costs. It is possible that the resumption in the United States of work on nuclear propulsion engines for flights to the Moon and Mars within the framework of the Space Research Initiative program with the planned participation of specialists from Russia and Kazakhstan will lead to the resumption of activity at the Semipalatinsk base and the implementation of a “Martian” expedition in the 2020s .
Main characteristics
Specific impulse on hydrogen: 910 - 980 sec(theoretically up to 1000 sec).
· Outflow velocity of the working fluid (hydrogen): 9100 - 9800 m/sec.
· Achievable thrust: up to hundreds and thousands of tons.
· Maximum operating temperatures: 3000°С - 3700°С (short-term switching on).
· Operating life: up to several thousand hours (periodic activation). /5/
11.Device
The design of the Soviet solid-phase nuclear rocket engine RD-0410
1 - line from the working fluid tank
2 - turbopump unit
3 - control drum drive
4 - radiation protection
5 - regulating drum
6 - retarder
7 - fuel assembly
8 - reactor vessel
9 - fire bottom
10 - nozzle cooling line
11- nozzle chamber
12 - nozzle
12.Operating principle
According to its operating principle, a TURE is a high-temperature reactor-heat exchanger into which a working fluid (liquid hydrogen) is introduced under pressure, and as it is heated to high temperatures (over 3000°C) it is ejected through a cooled nozzle. Heat regeneration in the nozzle is very beneficial, as it allows hydrogen to be heated much faster and, by utilizing a significant amount of thermal energy, the specific impulse can be increased to 1000 sec (9100-9800 m/s).
Nuclear rocket engine reactor
MsoNormalTable">
Working fluid
Density, g/cm3
Specific thrust (at specified temperatures in the heating chamber, °K), sec
0.071 (liquid)
0.682 (liquid)
1,000 (liquid)
No. Dann
No. Dann
No. Dann
(Note: The pressure in the heating chamber is 45.7 atm, expansion to a pressure of 1 atm with the same chemical composition of the working fluid) /6/
15.Benefits
The main advantage of TNREs over chemical rocket engines is the achievement of a higher specific impulse, significant energy reserves, compactness of the system and the ability to obtain very high thrust (tens, hundreds and thousands of tons in a vacuum. In general, the specific impulse achieved in a vacuum is greater than that of spent two-component chemical rocket fuel (kerosene-oxygen, hydrogen-oxygen) by 3-4 times, and when operating at the highest thermal intensity by 4-5 times.Currently in the USA and Russia there is significant experience in the development and construction of such engines, and if necessary (special programs space exploration) such engines can be produced in a short time and will have a reasonable cost.In the case of using TURE to accelerate spacecraft in space, and subject to the additional use of perturbation maneuvers using the gravitational field of large planets (Jupiter, Uranus, Saturn, Neptune) the achievable boundaries of studying the solar system are significantly expanding, and the time required to reach distant planets is significantly reduced. In addition, TNREs can be successfully used for devices operating in low orbits of giant planets using their rarefied atmosphere as a working fluid, or for operating in their atmosphere. /8/
16.Disadvantages
The main disadvantage of TNRE is the presence of a powerful flow of penetrating radiation (gamma radiation, neutrons), as well as the removal of highly radioactive uranium compounds, refractory compounds with induced radiation, and radioactive gases with the working fluid. In this regard, TURE is unacceptable for ground launches in order to avoid deterioration of the environmental situation at the launch site and in the atmosphere. /14/
17.Improving the characteristics of TURD. Hybrid turboprop engines
Like any rocket or any engine in general, a solid-phase nuclear jet engine has significant limitations on the most important characteristics achievable. These restrictions represent the inability of the device (TJRE) to operate in the temperature range exceeding the range of maximum operating temperatures of the engine’s structural materials. To expand the capabilities and significantly increase the main operating parameters of the TNRE, various hybrid schemes can be used in which the TNRE plays the role of a source of heat and energy and additional physical methods of accelerating the working fluids are used. The most reliable, practically feasible, and having high specific impulse and thrust characteristics is a hybrid scheme with an additional MHD circuit (magnetohydrodynamic circuit) for accelerating the ionized working fluid (hydrogen and special additives). /13/
18. Radiation hazard from nuclear propulsion engines.
A working nuclear engine is a powerful source of radiation - gamma and neutron radiation. Without taking special measures, radiation can cause unacceptable heating of the working fluid and structure in a spacecraft, embrittlement of metal structural materials, destruction of plastic and aging of rubber parts, damage to the insulation of electrical cables, and failure of electronic equipment. Radiation can cause induced (artificial) radioactivity of materials - their activation.
At present, the problem of radiation protection of spacecraft with nuclear propulsion engines is considered to be solved in principle. Fundamental issues related to the maintenance of nuclear propulsion engines at test stands and launch sites have also been resolved. Although an operating NRE poses a danger to operating personnel, already one day after the end of operation of the NRE, one can, without any personal protective equipment, stand for several tens of minutes at a distance of 50 m from the NRE and even approach it. The simplest means of protection allow operating personnel to enter the work area YARD shortly after the tests.
The level of contamination of launch complexes and the environment will apparently not be an obstacle to the use of nuclear propulsion engines on the lower stages of space rockets. The problem of radiation hazard for the environment and operating personnel is largely mitigated by the fact that hydrogen, used as a working fluid, is practically not activated when passing through the reactor. Therefore, the jet stream of a nuclear-powered engine is no more dangerous than the jet of a liquid-propellant rocket engine./4/
Conclusion
When considering the prospects for the development and use of nuclear propulsion engines in astronautics, one should proceed from the achieved and expected characteristics of various types of nuclear propulsion engines, from what their application can give to astronautics, and, finally, from the close connection of the problem of nuclear propulsion engines with the problem of energy supply in space and with issues of energy development at all.
As mentioned above, of all possible types of nuclear propulsion engines, the most developed are the thermal radioisotope engine and the engine with a solid-phase fission reactor. But if the characteristics of radioisotope nuclear propulsion engines do not allow us to hope for their widespread use in astronautics (at least in the near future), then the creation of solid-phase nuclear propulsion engines opens up great prospects for astronautics.
For example, a device has been proposed with an initial mass of 40,000 tons (i.e., approximately 10 times greater than that of the largest modern launch vehicles), with 1/10 of this mass accounting for the payload, and 2/3 for nuclear charges . If you detonate one charge every 3 seconds, then their supply will be enough for 10 days of continuous operation of the nuclear propulsion system. During this time, the device will accelerate to a speed of 10,000 km/s and in the future, after 130 years, it can reach the star Alpha Centauri.
Nuclear power plants have unique characteristics, which include virtually unlimited energy intensity, independence of operation from the environment, and immunity to external influences (cosmic radiation, meteorite damage, high and low temperatures, etc.). However, the maximum power of nuclear radioisotope installations is limited to a value of the order of several hundred watts. This limitation does not exist for nuclear reactor power plants, which determines the profitability of their use during long-term flights of heavy spacecraft in near-Earth space, during flights to the distant planets of the solar system and in other cases.
The advantages of solid-phase and other nuclear propulsion engines with fission reactors are most fully revealed in the study of such complex space programs as manned flights to the planets of the Solar System (for example, during an expedition to Mars). In this case, an increase in the specific impulse of the thruster makes it possible to solve qualitatively new problems. All these problems are greatly alleviated when using a solid-phase nuclear-propellant rocket engine with a specific impulse twice as high as that of modern liquid-propellant rocket engines. In this case, it also becomes possible to significantly reduce flight times.
It is most likely that in the near future solid-phase nuclear propulsion engines will become one of the most common rocket engines. Solid-phase nuclear propulsion engines can be used as devices for long-distance flights, for example, to such planets as Neptune, Pluto, and even to fly beyond the Solar System. However, for flights to the stars, a nuclear powered engine based on fission principles is not suitable. In this case, promising are nuclear engines or, more precisely, thermonuclear jet engines (TREs), operating on the principle of fusion reactions, and photonic jet engines (PREs), the source of momentum in which is the annihilation reaction of matter and antimatter. However, most likely humanity will use a different method of transportation to travel in interstellar space, different from jet.
In conclusion, I will give a paraphrase of Einstein’s famous phrase - to travel to the stars, humanity must come up with something that would be comparable in complexity and perception to a nuclear reactor for a Neanderthal!
LITERATURE
Sources:
1. "Rockets and People. Book 4 Moon Race" - M: Znanie, 1999.
2. http://www. lpre. de/energomash/index. htm
3. Pervushin “Battle for the Stars. Cosmic Confrontation” - M: knowledge, 1998.
4. L. Gilberg “Conquest of the sky” - M: Znanie, 1994.
5. http://epizodsspace. *****/bibl/molodtsov
6. “Engine”, “Nuclear engines for spacecraft”, No. 5 1999
7. "Engine", "Gas-phase nuclear engines for spacecraft",
No. 6, 1999
7. http://www. *****/content/numbers/263/03.shtml
8. http://www. lpre. de/energomash/index. htm
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10., Chekalin transport of the future.
M.: Knowledge, 1983.
11. , Chekalin space exploration. - M.:
Knowledge, 1988.
12. “Energy - Buran” - a step into the future // Science and life.-
13. Space technology. - M.: Mir, 1986.
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15.USSR in space. 2005 - M.: APN, 1989.
16. On the way to deep space // Energy. - 1985. - No. 6.
APPLICATION
Main characteristics of solid-phase nuclear jet engines
Manufacturer country | Engine | Thrust in vacuum, kN | Specific impulse, sec | Project work, year |
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NERVA/Lox Mixed Cycle |
A rocket engine in which the working fluid is either a substance (for example, hydrogen) heated by the energy released during a nuclear reaction or radioactive decay, or directly the products of these reactions. Distinguish... ... Big Encyclopedic Dictionary
A rocket engine in which the working fluid is either a substance (for example, hydrogen) heated by the energy released during a nuclear reaction or radioactive decay, or directly the products of these reactions. Is in… … encyclopedic Dictionary
nuclear rocket engine- branduolinis raketinis variklis statusas T sritis Gynyba apibrėžtis Raketinis variklis, kuriame reaktyvinė trauka sudaroma vykstant branduolinei arba termobranduolinei reakcijai. Branduoliniams raketiniams varikliams sudaroma kur kas didesnė… … Artilerijos terminų žodynas
- (Nuclear Jet) a rocket engine in which thrust is created due to the energy released during radioactive decay or a nuclear reaction. According to the type of nuclear reaction occurring in the nuclear engine, a radioisotope rocket engine is distinguished... ...
- (YRD) rocket engine, in which the source of energy is nuclear fuel. In a nuclear powered engine with a nuclear reactor. The torus heat released as a result of a nuclear chain reaction is transferred to the working fluid (for example, hydrogen). Nuclear reactor core... ...
This article should be Wikified. Please format it according to the article formatting rules. Nuclear rocket engine using a homogeneous solution of nuclear fuel salts (English... Wikipedia
Nuclear rocket engine (NRE) is a type of rocket engine that uses the energy of fission or fusion of nuclei to create jet thrust. They are actually reactive (heating the working fluid in a nuclear reactor and releasing gas through... ... Wikipedia
A jet engine, the energy source and working fluid of which is located in the vehicle itself. The rocket engine is the only one practically mastered for launching a payload into orbit of an artificial Earth satellite and for use in ... ... Wikipedia
- (RD) A jet engine that uses for its operation only substances and energy sources available in reserve on a moving vehicle (aircraft, ground, underwater). Thus, unlike air-jet engines (See... ... Great Soviet Encyclopedia
Isotopic rocket engine, a nuclear rocket engine that uses the decay energy of radioactive isotopes of chemicals. elements. This energy serves to heat the working fluid, or the working fluid is the decomposition products themselves, forming... ... Big Encyclopedic Polytechnic Dictionary
Alexander Losev
The rapid development of rocket and space technology in the 20th century was determined by the military-strategic, political and, to a certain extent, ideological goals and interests of the two superpowers - the USSR and the USA, and all state space programs were a continuation of their military projects, where the main task was the need to ensure defense capability and strategic parity with a potential enemy. The cost of creating equipment and operating costs were not of fundamental importance then. Enormous resources were allocated to the creation of launch vehicles and spacecraft, and the 108-minute flight of Yuri Gagarin in 1961 and the television broadcast of Neil Armstrong and Buzz Aldrin from the surface of the Moon in 1969 were not just triumphs of scientific and technical thought, they were also considered as strategic victories in battles of the Cold War.
But after the Soviet Union collapsed and dropped out of the race for world leadership, its geopolitical opponents, primarily the United States, no longer needed to implement prestigious but extremely costly space projects in order to prove to the whole world the superiority of the Western economic system and ideological concepts.
In the 90s, the main political tasks of previous years lost relevance, bloc confrontation was replaced by globalization, pragmatism prevailed in the world, so most space programs were curtailed or postponed; only the ISS remained as a legacy from the large-scale projects of the past. In addition, Western democracy has made all expensive government programs dependent on electoral cycles.
Voter support, necessary to gain or maintain power, forces politicians, parliaments and governments to lean toward populism and solve short-term problems, so spending on space exploration is reduced year after year.
Most of the fundamental discoveries were made in the first half of the twentieth century, and today science and technology have reached certain limits, moreover, the popularity of scientific knowledge has decreased throughout the world, and the quality of teaching mathematics, physics and other natural sciences has deteriorated. This has become the reason for the stagnation, including in the space sector, of the last two decades.
But now it becomes obvious that the world is approaching the end of another technological cycle based on the discoveries of the last century. Therefore, any power that will possess fundamentally new promising technologies at the time of change in the global technological structure will automatically ensure global leadership for at least the next fifty years.
Fundamental design of a nuclear propulsion engine with hydrogen as a working fluid
This is realized both in the United States, which has set a course for the revival of American greatness in all spheres of activity, and in China, which is challenging American hegemony, and in the European Union, which is trying with all its might to maintain its weight in the global economy.
There is an industrial policy there and they are seriously engaged in the development of their own scientific, technical and production potential, and the space sphere can become the best testing ground for testing new technologies and for proving or refuting scientific hypotheses that can lay the foundation for the creation of a fundamentally different, more advanced technology of the future.
And it is quite natural to expect that the United States will be the first country where deep space exploration projects will be resumed in order to create unique innovative technologies in the field of weapons, transport and structural materials, as well as in biomedicine and telecommunications
True, not even the United States is guaranteed success in creating revolutionary technologies. There is a high risk of ending up in a dead end when improving half-a-century old rocket engines based on chemical fuel, as Elon Musk’s SpaceX is doing, or when creating life support systems for long flights similar to those already implemented on the ISS.
Can Russia, whose stagnation in the space sector is becoming more noticeable every year, make a leap in the race for future technological leadership to remain in the club of superpowers, and not in the list of developing countries?
Yes, of course, Russia can, and moreover, a noticeable step forward has already been made in nuclear energy and in nuclear rocket engine technologies, despite the chronic underfunding of the space industry.
The future of astronautics is the use of nuclear energy. To understand how nuclear technology and space are connected, it is necessary to consider the basic principles of jet propulsion.
So, the main types of modern space engines are created on the principles of chemical energy. These are solid fuel accelerators and liquid rocket engines, in their combustion chambers the fuel components (fuel and oxidizer) enter into an exothermic physical and chemical combustion reaction, forming a jet stream that ejects tons of substance from the engine nozzle every second. The kinetic energy of the jet's working fluid is converted into a reactive force sufficient to propel the rocket. The specific impulse (the ratio of the thrust generated to the mass of the fuel used) of such chemical engines depends on the fuel components, the pressure and temperature in the combustion chamber, as well as the molecular weight of the gaseous mixture ejected through the engine nozzle.
And the higher the temperature of the substance and the pressure inside the combustion chamber, and the lower the molecular mass of the gas, the higher the specific impulse, and therefore the efficiency of the engine. Specific impulse is a quantity of motion and is usually measured in meters per second, just like speed.
In chemical engines, the highest specific impulse is provided by oxygen-hydrogen and fluorine-hydrogen fuel mixtures (4500–4700 m/s), but the most popular (and convenient to operate) have become rocket engines running on kerosene and oxygen, for example the Soyuz and Musk's Falcon rockets, as well as engines using unsymmetrical dimethylhydrazine (UDMH) with an oxidizer in the form of a mixture of nitrogen tetroxide and nitric acid (Soviet and Russian Proton, French Ariane, American Titan). Their efficiency is 1.5 times lower than that of hydrogen fuel engines, but an impulse of 3000 m/s and power are quite enough to make it economically profitable to launch tons of payload into near-Earth orbits.
But flights to other planets require much larger spacecraft than anything mankind has previously created, including the modular ISS. In these ships it is necessary to ensure long-term autonomous existence of the crews, and a certain supply of fuel and service life of the main engines and engines for maneuvers and orbit correction, to provide for the delivery of astronauts in a special landing module to the surface of another planet, and their return to the main transport ship, and then and the return of the expedition to Earth.
The accumulated engineering knowledge and chemical energy of engines make it possible to return to the Moon and reach Mars, so there is a high probability that humanity will visit the Red Planet in the next decade.
If we rely only on existing space technologies, then the minimum mass of the habitable module for a manned flight to Mars or to the satellites of Jupiter and Saturn will be approximately 90 tons, which is 3 times more than the lunar ships of the early 1970s, which means launch vehicles for their launch into reference orbits for further flight to Mars will be much superior to the Saturn 5 (launch weight 2965 tons) of the Apollo lunar project or the Soviet carrier Energia (launch weight 2400 tons). It will be necessary to create an interplanetary complex in orbit weighing up to 500 tons. A flight on an interplanetary ship with chemical rocket engines will require from 8 months to 1 year in one direction only, because you will have to do gravity maneuvers, using the gravitational force of the planets and a colossal supply of fuel to additionally accelerate the ship.
But using the chemical energy of rocket engines, humanity will not fly further than the orbit of Mars or Venus. We need different flight speeds of spacecraft and other more powerful energy of movement.
Modern design of a nuclear rocket engine Princeton Satellite Systems
To explore deep space, it is necessary to significantly increase the thrust-to-weight ratio and efficiency of the rocket engine, and therefore increase its specific impulse and service life. And to do this, it is necessary to heat a gas or working fluid substance with low atomic mass inside the engine chamber to temperatures several times higher than the chemical combustion temperature of traditional fuel mixtures, and this can be done using a nuclear reaction.
If, instead of a conventional combustion chamber, a nuclear reactor is placed inside a rocket engine, into the active zone of which a substance in liquid or gaseous form is supplied, then it, heated under high pressure up to several thousand degrees, will begin to be ejected through the nozzle channel, creating jet thrust. The specific impulse of such a nuclear jet engine will be several times greater than that of a conventional one with chemical components, which means that the efficiency of both the engine itself and the launch vehicle as a whole will increase many times over. In this case, an oxidizer for fuel combustion will not be required, and light hydrogen gas can be used as a substance that creates jet thrust; we know that the lower the molecular mass of the gas, the higher the impulse, and this will greatly reduce the mass of the rocket with better performance engine power.
A nuclear engine will be better than a conventional one, since in the reactor zone the light gas can be heated to temperatures exceeding 9 thousand degrees Kelvin, and a jet of such superheated gas will provide a much higher specific impulse than conventional chemical engines can provide. But this is in theory.
The danger is not even that when a launch vehicle with such a nuclear installation is launched, radioactive contamination of the atmosphere and space around the launch pad may occur; the main problem is that at high temperatures the engine itself, along with the spacecraft, may melt. Designers and engineers understand this and have been trying to find suitable solutions for several decades.
Nuclear rocket engines (NRE) already have their own history of creation and operation in space. The first development of nuclear engines began in the mid-1950s, that is, even before human flight into space, and almost simultaneously in both the USSR and the USA, and the very idea of using nuclear reactors to heat the working substance in a rocket engine was born along with the first rectors in mid-40s, that is, more than 70 years ago.
In our country, the initiator of the creation of nuclear propulsion was the thermal physicist Vitaly Mikhailovich Ievlev. In 1947, he presented a project that was supported by S. P. Korolev, I. V. Kurchatov and M. V. Keldysh. Initially, it was planned to use such engines for cruise missiles, and then install them on ballistic missiles. The development was undertaken by the leading defense design bureaus of the Soviet Union, as well as research institutes NIITP, CIAM, IAE, VNIINM.
The Soviet nuclear engine RD-0410 was assembled in the mid-60s at the Voronezh Chemical Automatics Design Bureau, where most liquid rocket engines for space technology were created.
Hydrogen was used as a working fluid in RD-0410, which in liquid form passed through a “cooling jacket”, removing excess heat from the walls of the nozzle and preventing it from melting, and then entered the reactor core, where it was heated to 3000K and released through the channel nozzles, thus converting thermal energy into kinetic energy and creating a specific impulse of 9100 m/s.
In the USA, the nuclear propulsion project was launched in 1952, and the first operating engine was created in 1966 and was named NERVA (Nuclear Engine for Rocket Vehicle Application). In the 60s and 70s, the Soviet Union and the United States tried not to yield to each other.
True, both our RD-0410 and the American NERVA were solid-phase nuclear propellant engines (nuclear fuel based on uranium carbides was in the solid state in the reactor), and their operating temperature was in the range of 2300–3100K.
To increase the temperature of the core without the risk of explosion or melting of the reactor walls, it is necessary to create such nuclear reaction conditions under which the fuel (uranium) turns into a gaseous state or turns into plasma and is held inside the reactor by a strong magnetic field, without touching the walls. And then the hydrogen entering the reactor core “flows around” the uranium in the gas phase, and turning into plasma, is ejected at a very high speed through the nozzle channel.
This type of engine is called a gas-phase nuclear propulsion engine. The temperatures of the gaseous uranium fuel in such nuclear engines can range from 10 thousand to 20 thousand degrees Kelvin, and the specific impulse can reach 50,000 m/s, which is 11 times higher than that of the most efficient chemical rocket engines.
The creation and use of gas-phase nuclear propulsion engines of open and closed types in space technology is the most promising direction in the development of space rocket engines and exactly what humanity needs to explore the planets of the Solar System and their satellites.
The first research on the gas-phase nuclear propulsion project began in the USSR in 1957 at the Research Institute of Thermal Processes (National Research Center named after M. V. Keldysh), and the decision to develop nuclear space power plants based on gas-phase nuclear reactors was made in 1963 by Academician V. P. Glushko (NPO Energomash), and then approved by a resolution of the CPSU Central Committee and the Council of Ministers of the USSR.
The development of gas-phase nuclear propulsion engines was carried out in the Soviet Union for two decades, but, unfortunately, was never completed due to insufficient funding and the need for additional fundamental research in the field of thermodynamics of nuclear fuel and hydrogen plasma, neutron physics and magnetohydrodynamics.
Soviet nuclear scientists and design engineers faced a number of problems, such as achieving criticality and ensuring the stability of the operation of a gas-phase nuclear reactor, reducing the loss of molten uranium during the release of hydrogen heated to several thousand degrees, thermal protection of the nozzle and magnetic field generator, and the accumulation of uranium fission products , selection of chemically resistant construction materials, etc.
And when the Energia launch vehicle began to be created for the Soviet Mars-94 program for the first manned flight to Mars, the nuclear engine project was postponed indefinitely. The Soviet Union did not have enough time, and most importantly, political will and economic efficiency, to land our cosmonauts on the planet Mars in 1994. This would be an undeniable achievement and proof of our leadership in high technology over the next few decades. But space, like many other things, was betrayed by the last leadership of the USSR. History cannot be changed, departed scientists and engineers cannot be brought back, and lost knowledge cannot be restored. A lot will have to be created anew.
But space nuclear power is not limited only to the sphere of solid- and gas-phase nuclear propulsion engines. Electrical energy can be used to create a heated flow of matter in a jet engine. This idea was first expressed by Konstantin Eduardovich Tsiolkovsky back in 1903 in his work “Exploration of world spaces using jet instruments.”
And the first electrothermal rocket engine in the USSR was created in the 1930s by Valentin Petrovich Glushko, a future academician of the USSR Academy of Sciences and the head of NPO Energia.
The operating principles of electric rocket engines can be different. They are usually divided into four types:
- electrothermal (heating or electric arc). In them, the gas is heated to temperatures of 1000–5000K and ejected from the nozzle in the same way as in a nuclear rocket engine.
- electrostatic engines (colloidal and ionic), in which the working substance is first ionized, and then positive ions (atoms devoid of electrons) are accelerated in an electrostatic field and are also ejected through the nozzle channel, creating jet thrust. Electrostatic engines also include stationary plasma engines.
- magnetoplasma and magnetodynamic rocket engines. There, the gas plasma is accelerated due to the Ampere force in the magnetic and electric fields intersecting perpendicularly.
- pulse rocket engines, which use the energy of gases resulting from the evaporation of a working fluid in an electric discharge.
The advantage of these electric rocket engines is the low consumption of the working fluid, efficiency up to 60% and high particle flow speed, which can significantly reduce the mass of the spacecraft, but there is also a disadvantage - low thrust density, and therefore low power, as well as the high cost of the working fluid (inert gases or vapors of alkali metals) to create plasma.
All of the listed types of electric motors have been implemented in practice and have been repeatedly used in space on both Soviet and American spacecraft since the mid-60s, but due to their low power they were used mainly as orbit correction engines.
From 1968 to 1988, the USSR launched a whole series of Cosmos satellites with nuclear installations on board. The types of reactors were named: “Buk”, “Topaz” and “Yenisei”.
The Yenisei project reactor had a thermal power of up to 135 kW and an electrical power of about 5 kW. The coolant was a sodium-potassium melt. This project was closed in 1996.
A real propulsion rocket motor requires a very powerful source of energy. And the best source of energy for such space engines is a nuclear reactor.
Nuclear energy is one of the high-tech industries where our country maintains a leading position. And a fundamentally new rocket engine is already being created in Russia and this project is close to successful completion in 2018. Flight tests are scheduled for 2020.
And if gas-phase nuclear propulsion is a topic for future decades that will have to be returned to after fundamental research, then its today’s alternative is a megawatt-class nuclear power propulsion system (NPPU), and it has already been created by Rosatom and Roscosmos enterprises since 2009.
NPO Krasnaya Zvezda, which is currently the world's only developer and manufacturer of space nuclear power plants, as well as the Research Center named after A. M. V. Keldysh, NIKIET im. N.A. Dollezhala, Research Institute NPO “Luch”, “Kurchatov Institute”, IRM, IPPE, RIAR and NPO Mashinostroeniya.
The nuclear power propulsion system includes a high-temperature gas-cooled fast neutron nuclear reactor with a turbomachine system for converting thermal energy into electrical energy, a system of refrigerator-emitters for removing excess heat into space, an instrumentation compartment, a block of sustainer plasma or ion electric motors, and a container for accommodating the payload. .
In a power propulsion system, a nuclear reactor serves as a source of electricity for the operation of electric plasma engines, while the gas coolant of the reactor passing through the core enters the turbine of the electric generator and compressor and returns back to the reactor in a closed loop, and is not thrown into space as in a nuclear propulsion engine, which makes the design more reliable and safe, and therefore suitable for manned space flight.
It is planned that the nuclear power plant will be used for a reusable space tug to ensure the delivery of cargo during the exploration of the Moon or the creation of multi-purpose orbital complexes. The advantage will be not only the reusable use of elements of the transport system (which Elon Musk is trying to achieve in his SpaceX space projects), but also the ability to deliver three times more cargo than on rockets with chemical jet engines of comparable power by reducing the launch mass of the transport system . The special design of the installation makes it safe for people and the environment on Earth.
In 2014, the first standard design fuel element (fuel element) for this nuclear electric propulsion system was assembled at JSC Mashinostroitelny Zavod in Elektrostal, and in 2016 tests of a reactor core basket simulator were carried out.
Now (in 2017) work is underway on the manufacture of structural elements of the installation and testing of components and assemblies on mock-ups, as well as autonomous testing of turbomachine energy conversion systems and prototype power units. Completion of the work is scheduled for the end of next 2018, however, since 2015, the backlog of the schedule began to accumulate.
So, as soon as this installation is created, Russia will become the first country in the world to possess nuclear space technologies, which will form the basis not only for future projects for the exploration of the Solar system, but also for terrestrial and extraterrestrial energy. Space nuclear power plants can be used to create systems for remote transmission of electricity to Earth or to space modules using electromagnetic radiation. And this will also become an advanced technology of the future, where our country will have a leading position.
Based on the plasma electric motors being developed, powerful propulsion systems will be created for long-distance human flights into space and, first of all, for the exploration of Mars, the orbit of which can be reached in just 1.5 months, and not in more than a year, as when using conventional chemical jet engines .
And the future always begins with a revolution in energy. And nothing else. Energy is primary and it is the amount of energy consumption that affects technical progress, defense capability and the quality of life of people.
NASA experimental plasma rocket engine
Soviet astrophysicist Nikolai Kardashev proposed a scale of development of civilizations back in 1964. According to this scale, the level of technological development of civilizations depends on the amount of energy that the planet's population uses for its needs. Thus, type I civilization uses all available resources available on the planet; Type II civilization - receives the energy of its star in the system of which it is located; and a type III civilization uses the available energy of its galaxy. Humanity has not yet matured to type I civilization on this scale. We use only 0.16% of the total potential energy reserve of planet Earth. This means that Russia and the whole world have room to grow, and these nuclear technologies will open the way for our country not only to space, but also to future economic prosperity.
And, perhaps, the only option for Russia in the scientific and technical sphere is to now make a revolutionary breakthrough in nuclear space technologies in order to overcome the many-year lag behind the leaders in one “leap” and be right at the origins of a new technological revolution in the next cycle of development of human civilization. Such a unique chance falls to a particular country only once every few centuries.
Unfortunately, Russia, which has not paid enough attention to fundamental sciences and the quality of higher and secondary education over the past 25 years, risks losing this chance forever if the program is curtailed and a new generation of researchers does not replace the current scientists and engineers. The geopolitical and technological challenges that Russia will face in 10–12 years will be very serious, comparable to the threats of the mid-twentieth century. In order to preserve the sovereignty and integrity of Russia in the future, it is now urgently necessary to begin training specialists capable of responding to these challenges and creating something fundamentally new.
There are only about 10 years to transform Russia into a global intellectual and technological center, and this cannot be done without a serious change in the quality of education. For a scientific and technological breakthrough, it is necessary to return to the education system (both school and university) systematic views on the picture of the world, scientific fundamentality and ideological integrity.
As for the current stagnation in the space industry, this is not scary. The physical principles on which modern space technologies are based will be in demand for a long time in the conventional satellite services sector. Let us remember that humanity used sail for 5.5 thousand years, and the era of steam lasted almost 200 years, and only in the twentieth century the world began to change rapidly, because another scientific and technological revolution took place, which launched a wave of innovation and a change in technological structures, which ultimately changed both the world economy and politics. The main thing is to be at the origins of these changes [email protected] ,
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Often in general educational publications about astronautics, they do not distinguish the difference between a nuclear rocket engine (NRE) and a nuclear electric propulsion system (NURE). However, these abbreviations hide not only the difference in the principles of converting nuclear energy into rocket thrust, but also a very dramatic history of the development of astronautics.
The drama of history lies in the fact that if research on nuclear propulsion and nuclear propulsion in both the USSR and the USA, which had been stopped mainly for economic reasons, had continued, then human flights to Mars would have long ago become commonplace.
It all started with atmospheric aircraft with a ramjet nuclear engine
Designers in the USA and USSR considered “breathing” nuclear installations capable of drawing in outside air and heating it to colossal temperatures. Probably, this principle of thrust generation was borrowed from ramjet engines, only instead of rocket fuel, the fission energy of atomic nuclei of uranium dioxide 235 was used.In the USA, such an engine was developed as part of the Pluto project. The Americans managed to create two prototypes of the new engine - Tory-IIA and Tory-IIC, which even powered the reactors. The installation capacity was supposed to be 600 megawatts.
The engines developed as part of the Pluto project were planned to be installed on cruise missiles, which in the 1950s were created under the designation SLAM (Supersonic Low Altitude Missile, supersonic low-altitude missile).
The United States planned to build a rocket 26.8 meters long, three meters in diameter, and weighing 28 tons. The rocket body was supposed to contain a nuclear warhead, as well as a nuclear propulsion system having a length of 1.6 meters and a diameter of 1.5 meters. Compared to other sizes, the installation looked very compact, which explains its direct-flow principle of operation.
The developers believed that, thanks to the nuclear engine, the SLAM missile's flight range would be at least 182 thousand kilometers.
In 1964, the US Department of Defense closed the project. The official reason was that in flight, a nuclear-powered cruise missile pollutes everything around too much. But in fact, the reason was the significant costs of maintaining such rockets, especially since by that time rocketry was rapidly developing based on liquid-propellant rocket engines, the maintenance of which was much cheaper.
The USSR remained faithful to the idea of creating a ramjet design for a nuclear powered engine much longer than the United States, closing the project only in 1985. But the results turned out to be much more significant. Thus, the first and only Soviet nuclear rocket engine was developed at the Khimavtomatika design bureau, Voronezh. This is RD-0410 (GRAU Index - 11B91, also known as “Irbit” and “IR-100”).
The RD-0410 used a heterogeneous thermal neutron reactor, the moderator was zirconium hydride, the neutron reflectors were made of beryllium, the nuclear fuel was a material based on uranium and tungsten carbides, with about 80% enrichment in the 235 isotope.
The design included 37 fuel assemblies, covered with thermal insulation that separated them from the moderator. The design provided that the hydrogen flow first passed through the reflector and moderator, maintaining their temperature at room temperature, and then entered the core, where it cooled the fuel assemblies, heating up to 3100 K. At the stand, the reflector and moderator were cooled by a separate hydrogen flow.
The reactor went through a significant series of tests, but was never tested for its full operating duration. However, the outside reactor components were completely exhausted.
Technical characteristics of RD 0410
Thrust in void: 3.59 tf (35.2 kN)
Reactor thermal power: 196 MW
Specific thrust impulse in vacuum: 910 kgf s/kg (8927 m/s)
Number of starts: 10
Working resource: 1 hour
Fuel components: working fluid - liquid hydrogen, auxiliary substance - heptane
Weight with radiation protection: 2 tons
Engine dimensions: height 3.5 m, diameter 1.6 m.
Relatively small overall dimensions and weight, high temperature of nuclear fuel (3100 K) with an effective cooling system with a hydrogen flow indicate that the RD0410 is an almost ideal prototype of a nuclear propulsion engine for modern cruise missiles. And, taking into account modern technologies for producing self-stopping nuclear fuel, increasing the resource from an hour to several hours is a very real task.
Nuclear rocket engine designs
A nuclear rocket engine (NRE) is a jet engine in which the energy generated during a nuclear decay or fusion reaction heats the working fluid (most often hydrogen or ammonia).There are three types of nuclear propulsion engines depending on the type of fuel for the reactor:
- solid phase;
- liquid phase;
- gas phase.
In gas-phase nuclear propellant engines, the fuel (for example, uranium) and the working fluid are in a gaseous state (in the form of plasma) and are held in the working area by an electromagnetic field. Uranium plasma heated to tens of thousands of degrees transfers heat to the working fluid (for example, hydrogen), which, in turn, being heated to high temperatures forms a jet stream.
Based on the type of nuclear reaction, a distinction is made between a radioisotope rocket engine, a thermonuclear rocket engine and a nuclear engine itself (the energy of nuclear fission is used).
An interesting option is also a pulsed nuclear rocket engine - it is proposed to use a nuclear charge as a source of energy (fuel). Such installations can be of internal and external types.
The main advantages of nuclear powered engines are:
- high specific impulse;
- significant energy reserves;
- compactness of the propulsion system;
- the possibility of obtaining very high thrust - tens, hundreds and thousands of tons in a vacuum.
- 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.
Nuclear propulsion system
Considering that it is impossible to obtain any reliable information about nuclear power plants from publications, including from scientific articles, the operating principle of such installations is best considered using examples of open patent materials, although they contain know-how.For example, the outstanding Russian scientist Anatoly Sazonovich Koroteev, the author of the invention under the patent, provided a technical solution for the composition of equipment for a modern YARDU. Below I present part of the said patent document verbatim and without comment.
The essence of the proposed technical solution is illustrated by the diagram presented in the drawing. A nuclear propulsion system operating in propulsion-energy mode contains an electric propulsion system (EPS) (the example diagram shows two electric rocket engines 1 and 2 with corresponding feed systems 3 and 4), a reactor installation 5, a turbine 6, a compressor 7, a generator 8, heat exchanger-recuperator 9, Ranck-Hilsch vortex tube 10, refrigerator-radiator 11. In this case, turbine 6, compressor 7 and generator 8 are combined into a single unit - a turbogenerator-compressor. The nuclear propulsion unit is equipped with pipelines 12 of the working fluid and electrical lines 13 connecting the generator 8 and the electric propulsion unit. The heat exchanger-recuperator 9 has the so-called high-temperature 14 and low-temperature 15 working fluid inputs, as well as high-temperature 16 and low-temperature 17 working fluid outputs.Links:The output of the reactor unit 5 is connected to the input of turbine 6, the output of turbine 6 is connected to the high-temperature input 14 of the heat exchanger-recuperator 9. The low-temperature output 15 of the heat exchanger-recuperator 9 is connected to the entrance to the Ranck-Hilsch vortex tube 10. The Ranck-Hilsch vortex tube 10 has two outputs , one of which (via the “hot” working fluid) is connected to the radiator refrigerator 11, and the other (via the “cold” working fluid) is connected to the input of the compressor 7. The output of the radiator refrigerator 11 is also connected to the input to the compressor 7. Compressor output 7 is connected to the low-temperature 15 input to the heat exchanger-recuperator 9. The high-temperature output 16 of the heat exchanger-recuperator 9 is connected to the input to the reactor installation 5. Thus, the main elements of the nuclear power plant are interconnected by a single circuit of the working fluid.
The nuclear power plant works as follows. The working fluid heated in the reactor installation 5 is sent to the turbine 6, which ensures the operation of the compressor 7 and the generator 8 of the turbogenerator-compressor. Generator 8 generates electrical energy, which is sent through electrical lines 13 to electric rocket engines 1 and 2 and their supply systems 3 and 4, ensuring their operation. After leaving the turbine 6, the working fluid is sent through the high-temperature inlet 14 to the heat exchanger-recuperator 9, where the working fluid is partially cooled.
Then, from the low-temperature outlet 17 of the heat exchanger-recuperator 9, the working fluid is directed into the Ranque-Hilsch vortex tube 10, inside which the working fluid flow is divided into “hot” and “cold” components. The “hot” part of the working fluid then goes to the refrigerator-emitter 11, where this part of the working fluid is effectively cooled. The “cold” part of the working fluid goes to the inlet of the compressor 7, and after cooling, the part of the working fluid leaving the radiating refrigerator 11 also follows there.
Compressor 7 supplies the cooled working fluid to the heat exchanger-recuperator 9 through the low-temperature inlet 15. This cooled working fluid in the heat exchanger-recuperator 9 provides partial cooling of the counter flow of the working fluid entering the heat exchanger-recuperator 9 from the turbine 6 through the high-temperature inlet 14. Next, the partially heated working fluid (due to heat exchange with the counter flow of the working fluid from the turbine 6) from the heat exchanger-recuperator 9 through the high-temperature outlet 16 again enters the reactor installation 5, the cycle is repeated again.
Thus, a single working fluid located in a closed loop ensures continuous operation of the nuclear power plant, and the use of a Ranque-Hilsch vortex tube as part of the nuclear power plant in accordance with the claimed technical solution improves the weight and size characteristics of the nuclear power plant, increases the reliability of its operation, simplifies its design and makes it possible to increase efficiency of nuclear power plants in general.
IN one of the sections On LiveJournal, an electronics engineer constantly writes about nuclear and thermonuclear machines - reactors, installations, research laboratories, accelerators, as well as about. The new Russian missile, testimony during the annual presidential address, aroused the keen interest of the blogger. And this is what he found on this topic.
Yes, historically there have been developments of cruise missiles with a ramjet nuclear air engine: the SLAM missile in the USA with the TORY-II reactor, the Avro Z-59 concept in the UK, developments in the USSR.
A modern rendering of the Avro Z-59 rocket concept, weighing about 20 tons.
However, all this work was carried out in the 60s as R&D of varying degrees of depth (the United States went the furthest, as discussed below) and was not continued in the form of models in service. We didn’t get it for the same reason as many other Atom Age developments - planes, trains, missiles with nuclear power plants. All these vehicle options, with some advantages provided by the insane energy density in nuclear fuel, have very serious disadvantages - high cost, complexity of operation, requirements for constant security, and finally, unsatisfactory development results, about which little is usually known (by publishing the results of R&D it is more profitable for all parties display achievements and hide failures).
In particular, for cruise missiles it is much easier to create a carrier (submarine or aircraft) that will “drag” many missile launchers to the launch site than to fool around with a small fleet (and it is incredibly difficult to develop a large fleet) of cruise missiles launched from one’s own territory. A universal, cheap, mass-produced product ultimately won out over a small-scale, expensive product with ambiguous advantages. Nuclear cruise missiles have not gone beyond ground testing.
This conceptual dead end of the 60s of the Kyrgyz Republic with nuclear power plants, in my opinion, is still relevant now, so the main question to the one shown is “why??”. But what makes it even more prominent are the problems that arise during the development, testing and operation of such weapons, which we will discuss further.
So, let's start with the reactor. The SLAM and Z-59 concepts were three-mach low-flying rockets of impressive size and weight (20+ tons after the launch boosters were jettisoned). The terribly expensive low-flying supersonic made it possible to make maximum use of the presence of a practically unlimited source of energy on board; in addition, an important feature of the nuclear air jet engine is improved operating efficiency (thermodynamic cycle) with increasing speed, i.e. the same idea, but at speeds of 1000 km/h it would have a much heavier and larger engine. Finally, 3M at an altitude of a hundred meters in 1965 meant invulnerability to air defense. It turns out that earlier the concept of missile launchers with nuclear power was “tied up” at high speed, where the advantages of the concept were strong, and competitors with hydrocarbon fuel were weakening. The shown rocket, in my opinion look, transonic or subsonic (if, of course, you believe that it is she in the video). But at the same time, the size of the reactor has decreased significantly compared to TORY-II from the SLAM rocket, where it was as much as 2 meters including the radial neutron reflector made of graphite
Is it even possible to install a reactor with a diameter of 0.4-0.6 meters?
Let's start with a fundamentally minimal reactor - a Pu239 pig. A good example of the implementation of such a concept is the Kilopower space reactor, which, however, uses U235. The diameter of the reactor core is only 11 centimeters! If we switch to plutonium 239, the size of the core will drop by another 1.5-2 times. Now from the minimum size we will begin to step towards a real nuclear air jet engine, remembering the difficulties.
The very first thing to add to the size of the reactor is the size of the reflector - in particular, in Kilopower BeO triples the size. Secondly, we cannot use U or Pu blanks - they will simply burn out in the air flow in just a minute. A shell is needed, for example from incaloy, which resists instant oxidation up to 1000 C, or other nickel alloys with a possible ceramic coating. The introduction of a large amount of shell material into the core increases the required amount of nuclear fuel several times at once - after all, the “unproductive” absorption of neutrons in the core has now increased sharply!
Moreover, the metal form of U or Pu is no longer suitable - these materials themselves are not refractory (plutonium generally melts at 634 C), and they also interact with the material of the metal shells. We convert the fuel into the classical form of UO2 or PuO2 - we get another dilution of the material in the core, this time with oxygen.
Finally, let's remember the purpose of the reactor. We need to pump a lot of air through it, to which we will give off heat. Approximately 2/3 of the space will be occupied by “air tubes”.
As a result, the minimum diameter of the core grows to 40-50 cm (for uranium), and the diameter of the reactor with a 10-centimeter beryllium reflector to 60-70 cm. My knee-jerk estimates “by analogy” are confirmed by the design of a nuclear jet engine MITEE , designed for flights in the atmosphere of Jupiter. This completely paper project (for example, the core temperature is assumed to be 3000 K, and the walls are made of beryllium, which can withstand at most 1200 K) has a core diameter calculated from neutronics of 55.4 cm, despite the fact that cooling with hydrogen makes it possible to slightly reduce the size of the channels through which the coolant is pumped .
In my opinion, an airborne nuclear jet engine can be shoved into a rocket with a diameter of about a meter, which, however, is still not radically larger than the stated 0.6-0.74 m, but is still alarming. One way or another, the nuclear power plant will have a power of ~several megawatt, powered by ~10^16 decays per second. This means that the reactor itself will create a radiation field of several tens of thousands of roentgens at the surface, and up to a thousand roentgens along the entire rocket. Even installing several hundred kg of sector protection will not significantly reduce these levels, because Neutron and gamma rays will be reflected from the air and “bypass the protection.”
In a few hours, such a reactor will produce ~10^21-10^22 atoms of fission products c with an activity of several (several tens) petabecquerels, which even after shutdown will create a background of several thousand roentgens near the reactor.
The rocket design will be activated to about 10^14 Bq, although the isotopes will be primarily beta emitters and are only dangerous by bremsstrahlung X-rays. The background from the structure itself can reach tens of roentgens at a distance of 10 meters from the rocket body.
All this “fun” gives the idea that the development and testing of such a rocket is a task on the verge of the possible. It is necessary to create a whole set of radiation-resistant navigation and control equipment, to test it all in a fairly comprehensive way (radiation, temperature, vibration - and all this for statistics). Flight tests with a working reactor can at any moment turn into a radiation disaster with a release of hundreds of terrabecquerels to several petabecquerels. Even without catastrophic situations, depressurization of individual fuel elements and the release of radionuclides are very likely.
Of course, in Russia there are still Novozemelsky test site on which such tests can be carried out, but this would be contrary to the spirit of the agreement on banning nuclear weapons testing in three environments (the ban was introduced in order to prevent systematic pollution of the atmosphere and ocean by radionuclides).
Finally, I wonder who in the Russian Federation could develop such a reactor. Traditionally, the Kurchatov Institute (general design and calculations), Obninsk IPPE (experimental testing and fuel), and the Luch Research Institute in Podolsk (fuel and materials technology) were initially involved in high-temperature reactors. Later, the NIKIET team became involved in the design of such machines (for example, the IGR and IVG reactors are prototypes of the core of the RD-0410 nuclear rocket engine).
Today NIKIET has a team of designers who carry out work on reactor design ( high-temperature gas-cooled RUGK , fast reactors MBIR, ), and IPPE and Luch continue to engage in related calculations and technologies, respectively. In recent decades, the Kurchatov Institute has moved more toward the theory of nuclear reactors.
In summary, I would like to say that the creation of a cruise missile with air-jet engines with a nuclear power plant is generally a feasible task, but at the same time extremely expensive and complex, requiring a significant mobilization of human and financial resources, it seems to me to a greater extent than all other announced projects (" Sarmat", "Dagger", "Status-6", "Vanguard"). It is very strange that this mobilization did not leave the slightest trace. And most importantly, it is completely unclear what the benefits of obtaining such types of weapons (against the background of existing carriers) are, and how they can outweigh the numerous disadvantages - issues of radiation safety, high cost, incompatibility with strategic arms reduction treaties.
P.S. However, “sources” are already beginning to soften the situation: “A source close to the military-industrial complex said “ Vedomosti "that radiation safety was ensured during rocket testing. The nuclear installation on board was represented by an electrical mock-up, the source says.
