Liquid-propellant rocket engines gave man the opportunity to go into space - into near-Earth orbits. However, such rockets burn 99% of the fuel in the first few minutes of flight. The remaining fuel may not be enough to travel to other planets, and the speed will be so low that the voyage will take tens or hundreds of years. Nuclear engines can solve the problem. How? Let's figure it out together.

The principle of operation of a jet engine is very simple: it converts fuel into the kinetic energy of the jet (the law of conservation of energy), due to the direction of this jet, the rocket moves in space (the law of conservation of momentum). It is important to understand that we cannot accelerate a rocket or an aircraft to a speed greater than the speed of the outflow of fuel - hot gas thrown back.

New Horizons spacecraft

What distinguishes an efficient engine from an unsuccessful or outdated counterpart? First of all, how much fuel the engine will need to accelerate the rocket to the desired speed. This most important parameter of a rocket engine is called specific impulse, which is defined as the ratio of total momentum to fuel consumption: the larger this figure, the more efficient the rocket engine. If the rocket consists almost entirely of fuel (which means that there is no place for a payload in it, the limiting case), the specific impulse can be considered equal to the speed of the fuel (propellant) outflow from the rocket nozzle. Launching a rocket is an extremely expensive undertaking; every gram of not only the payload, but also the fuel, which also weighs and takes up space, is taken into account. Therefore, engineers select more and more active fuel, the unit of which would give the maximum return, increasing the specific impulse.

The vast majority of rockets in history and today were equipped with engines that use the chemical reaction of combustion (oxidation) of fuel.

They made it possible to reach the Moon, Venus, Mars and even the planets of the far zone - Jupiter, Saturn and Neptune. True, space expeditions took months and years (automatic stations Pioneer, Voyager, New Horizons, etc.). It should be noted that all such rockets consume a significant part of the fuel to take off from the Earth, and then continue to fly by inertia with rare moments of turning on the engine.

Pioneer spacecraft

Such engines are suitable for launching rockets into near-Earth orbit, but in order to accelerate it to at least a quarter of the speed of light, an incredible amount of fuel will be needed (calculations show that 103200 grams of fuel are needed, despite the fact that the mass of our Galaxy is no more than 1056 grams). It is obvious that in order to reach the nearest planets, and even more so the stars, we need sufficiently high speeds, which liquid-fuel rockets are not able to provide.

Gas-phase nuclear engine

Deep space is a completely different matter. Take, for example, Mars, "lived in" by science fiction writers far and wide: it is well studied and scientifically promising, and most importantly, it is close like no other. The point is for the “space bus”, which can deliver the crew there in a reasonable time, that is, as quickly as possible. But there are problems with interplanetary transport. It is difficult to accelerate it to the desired speed, while maintaining an acceptable size and spending a reasonable amount of fuel.

RS-25 (Rocket System 25) is a liquid propellant rocket engine manufactured by Rocketdine, USA. It was used on the glider of the space transport system "Space Shuttle", each of which was equipped with three such engines. Better known as the SSME engine (English Space Shuttle Main Engine - the main engine of the space shuttle). The main fuel components are liquid oxygen (oxidizer) and hydrogen (fuel). RS-25 uses a closed cycle scheme (with afterburning of generator gas).

The solution could be a "peaceful atom" pushing spaceships. On the creation of a light and compact device capable of launching at least itself into orbit, engineers thought back in the late 50s of the last century. The main difference between nuclear engines and rockets with internal combustion engines is that kinetic energy is obtained not due to the combustion of fuel, but due to the thermal energy of the decay of radioactive elements. Let's compare these approaches.

From liquid engines a hot "cocktail" of exhaust gases comes out (the law of conservation of momentum), formed during the reaction of fuel and oxidizer (the law of conservation of energy). In most cases, this is a combination of oxygen and hydrogen (the result of burning hydrogen is ordinary water). H2O has a much larger molar mass than hydrogen or helium, so it is more difficult to accelerate, the specific impulse for such an engine is 4,500 m/s.

NASA Ground Tests new system launch space rockets, 2016 (Utah, USA). These engines will be installed on the Orion spacecraft, which is planning a mission to Mars.

IN nuclear engines it is proposed to use only hydrogen and accelerate (heat) it due to the energy of nuclear decay. Thus, there is a saving on the oxidizer (oxygen), which is already wonderful, but not all. Since hydrogen has a relatively low specific gravity, it is easier for us to accelerate it to higher speeds. Of course, other heat-sensitive gases (helium, argon, ammonia, and methane) can also be used, but all of them are at least two times inferior to hydrogen in the most important thing - the achievable specific impulse (more than 8 km / s).

So is it worth losing? The gain is so great that neither the complexity of the design and control of the reactor, nor its big weight, not even a radiation hazard. Moreover, no one is going to start from the surface of the Earth - the assembly of such ships will be carried out in orbit.

"Flying" reactor

How does a nuclear engine work? Reactor in space engine much smaller and more compact than their ground counterparts, but all the main components and control mechanisms are fundamentally the same. The reactor acts as a heater into which liquid hydrogen is supplied. Temperatures in the core reach (and can exceed) 3000 degrees. Then the heated gas is released through the nozzle.

However, such reactors emit harmful radiation. To protect the crew and numerous electronic equipment Radiation needs to be taken seriously. Therefore, projects for interplanetary ships with a nuclear engine often resemble an umbrella: the engine is located in a shielded separate block connected to the main module by a long truss or pipe.

"Combustion chamber" The core of the reactor serves as a nuclear engine, in which hydrogen supplied under high pressure is heated to 3000 degrees or more. This limit is only determined by the heat resistance of the reactor materials and the properties of the fuel, although increasing the temperature increases the specific impulse.

Fuel elements- these are heat-resistant ribbed (to increase the heat transfer area) cylinders-"glasses" filled with uranium pellets. They are “washed” by the gas flow, which plays the role of both the working fluid and the reactor cooler. The entire structure is insulated with beryllium reflective screens that do not release dangerous radiation to the outside. To control the release of heat, special rotary drums are located next to the screens.

There are a number of promising designs of nuclear rocket engines, the implementation of which is waiting in the wings. After all, they will be mainly used in interplanetary travel, which, apparently, is just around the corner.

Nuclear engine projects

These projects were shelved for various reasons - lack of money, design complexity, or even the need to assemble and install in outer space.

"ORION" (USA, 1950–1960)

The project of a manned nuclear-pulse spacecraft ("explosive") for the study of interplanetary and interstellar space.

Principle of operation. From the ship's engine, in the direction opposite to the flight, a nuclear charge of a small equivalent is ejected and detonated at a relatively short distance from the ship (up to 100 m). The impact force bounces off the massive reflective plate at the ship's tail, "pushing" it forward.

"PROMETHEUS" (USA, 2002–2005)

NASA space agency project to develop a nuclear engine for spacecraft.

Principle of operation. The spacecraft's engine was supposed to consist of ionized particles that create thrust, and a compact nuclear reactor that provides energy for the installation. The ion engine produces a thrust of about 60 grams, but will be able to work constantly. Ultimately, the ship will gradually be able to pick up a huge speed - 50 km / s, expending a minimum amount of energy.

"PLUTON" (USA, 1957–1964)

Project for the development of a nuclear ramjet engine.

Principle of operation. Air through the front of the vehicle enters the nuclear reactor, where it is heated. Hot air expands, acquires greater speed and is released through the nozzle, providing the necessary thrust.

NERVA (USA, 1952–1972)

(eng. Nuclear Engine for Rocket Vehicle Application) is a joint program of the US Atomic Energy Commission and NASA to create a nuclear rocket engine.

Principle of operation. Liquid hydrogel is fed into a special compartment, where it is heated by a nuclear reactor. The hot gas expands and is released in the nozzle, creating thrust.

Sergeev Alexey, 9 "A" class MOU "Secondary School No. 84"

Scientific consultant: , Deputy Director of the non-profit partnership for scientific and innovative activities "Tomsk Atomic Center"

Supervisor: , teacher of physics, MOU "Secondary School No. 84" ZATO Seversk

Introduction

Propulsion systems on board a spacecraft are designed to generate thrust or momentum. According to the type of thrust used by the propulsion system, they are divided into chemical (CRD) and non-chemical (NCRD). HRD are divided into liquid (LRE), solid fuel (RDTT) and combined (KRD). 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 fuels. After, in the second half of the 20th century, thousands of flights were carried out using mainly LRE 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 more and more unprofitable, although many rocket engines have been developed. Most likely, the possibilities of LRE and solid propellant rocket engines have completely exhausted themselves. The reason here is that the specific impulse of all chemical rocket engines is low and does not exceed 5000 m/s, which requires long-term operation of the propulsion system and, accordingly, large reserves of fuel to develop sufficiently high speeds, or, as is customary in astronautics, large values of the Tsiolkovsky number, t i.e. the ratio of the mass of a fueled rocket to the mass of an empty one. Thus, RN Energia, which puts 100 tons of payload into low orbit, has a launch mass of about 3,000 tons, which gives the Tsiolkovsky number a value in the range of 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, namely, the minimum mass required to provide everything necessary for the crew starting to Mars taking into account the fuel supply for the return flight to the 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 rocket 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 different from chemical propulsion. The most promising in this regard are electric jet engines (EP), thermochemical rocket engines and nuclear jet (YARD).

1.Basic concepts

A rocket engine is a jet engine that does not use the environment (air, water) for operation. The most widely used chemical rocket engines. Other types of rocket engines are being developed and tested - electric, nuclear and others. At space stations and vehicles, the simplest rocket engines operating on compressed gases are also widely used. They usually use nitrogen as the 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, sustainer, control and others. Rocket engines are mainly 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 engines. This is due to the fact that such an engine is refueled at the factory and does not require maintenance for the entire period of storage and service of the rocket itself. Solid propellant engines are often used as boosters for space rockets. Especially widely, in this capacity, they are used in the USA, France, Japan and China.

Liquid propellant rocket engines have higher thrust characteristics than solid propellant ones. Therefore, they are used to launch space rockets into orbit around the Earth and on interplanetary flights. The main liquid propellants for rockets are kerosene, heptane (dimethylhydrazine), and liquid hydrogen. For such fuels, an oxidizing agent (oxygen) is required. Nitric acid and liquefied oxygen are used as an oxidizing agent 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 rockets

Engines for space flights differ from terrestrial ones in that they, with the smallest possible mass and volume, must produce as much power as possible. In addition, they are subject to such requirements as exclusively high efficiency and reliability, considerable operating time. According to the type of energy used, spacecraft propulsion systems are divided into four types: thermochemical, nuclear, electric, solar-sailing. Each of these types has its own advantages and disadvantages and can be used in certain conditions.

Currently, spacecraft, orbital stations and unmanned Earth satellites are launched into space by rockets equipped with powerful thermochemical engines. There are also miniature low thrust engines. This is a reduced 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 the internal combustion engine, the furnace of a steam boiler - wherever combustion takes place, atmospheric oxygen takes the most active part. There is no air in outer space, and for the operation of rocket engines in outer space, it is necessary to have two components - fuel and an oxidizer.

In liquid thermochemical rocket engines, alcohol, kerosene, gasoline, aniline, hydrazine, dimethylhydrazine, liquid hydrogen are used as fuel. As an oxidizing agent, liquid oxygen, hydrogen peroxide, Nitric acid. It is possible that liquid fluorine will be used as an oxidizing agent in the future, when methods for storing and using such an active chemical are invented.

Fuel and oxidizer for liquid-propellant jet engines are stored separately, in special tanks and pumped into the combustion chamber. When they are combined in the combustion chamber, a temperature of up to 3000 - 4500 ° C develops.

Combustion products, expanding, acquire a speed of 2500 to 4500 m/s. Starting from the engine housing, they create jet thrust. At the same time, the greater the mass and speed of the outflow of gases, the greater the thrust force of the engine.

It is customary to estimate the specific thrust of engines by the amount of thrust created by a unit mass of fuel burned in one second. This value is called the specific impulse of the rocket engine and is measured in seconds (kg of thrust / kg of burned 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. The 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 scheme of a liquid propellant rocket engine works as follows. Compressed gas creates the necessary pressure in the 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. Also, an oxidizing agent is injected into the combustion chamber through the nozzles.

In any car, during the combustion of fuel, large heat flows are formed that heat the walls of the engine. If you do not cool the walls of the chamber, then it will quickly burn out, no matter what material it is made of. A liquid-propellant jet engine is usually cooled with one of the propellant components. For this, the chamber is made two-wall. The cold fuel component flows in the gap between the walls.

Aluminum" href="/text/category/aluminij/" rel="bookmark">aluminum, etc. Especially as an additive to conventional fuels, such as hydrogen-oxygen. Such "triple compositions" are able to provide the highest possible speed for chemical fuels outflow - 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 on solid fuel - Solid propellant rocket engine. The fuel - for example, special gunpowder - is located directly in the combustion chamber. The 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 (starting, marching or combined). For solid propellant rockets used in military affairs are characterized by the presence of starting and sustainer engines.The starting solid propellant rocket engine develops high thrust for a very short time, which is necessary for the rocket to leave the launcher and its initial acceleration. A marching solid propellant rocket engine is designed to maintain a constant rocket flight speed in the main (cruising) section of the flight path. The differences between them are 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 burning, on which the operating time and engine thrust depend. Unlike such rockets, space launch vehicles for launching Earth satellites, orbital stations and spaceships, as well as interplanetary stations, operate only in the starting mode from the launch of the rocket until the object is put into orbit around the Earth or onto an interplanetary trajectory. In general, solid propellant rocket motors do not have many advantages over liquid propellant motors: they are easy to manufacture, long time can be stored, always ready for action, relatively explosion-proof. But in terms of specific thrust, solid propellant engines are 10-30% inferior to liquid ones.

4. Electric rocket motors

Almost all of the rocket engines discussed above develop tremendous thrust and are designed to put spacecraft into orbit around the Earth and accelerate them to space speeds for interplanetary flights. It is a completely different matter - propulsion systems for spacecraft already launched into orbit or onto an interplanetary trajectory. Here, as a rule, low-power motors (several kilowatts or even watts) are needed that can work hundreds and thousands of hours and turn on and off repeatedly. They allow you to maintain flight in orbit or along a given trajectory, compensating for the resistance to flight created by the upper 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. The methods of heating the working fluid are different, but in reality it is mainly used electric arc. It proved to be very reliable and withstands a large number of inclusions. Hydrogen is used as the working fluid in electric arc engines. By using 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 plasma outflow velocity from the thruster 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 bring the outflow velocity 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) in the famous gas dynamic laboratory (GDL). / 10 /

5.Other types of engines

There are also more exotic projects of 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. There are, while at the theoretical or laboratory stage, the following projects of rocket engines

Pulse nuclear rocket engines using the energy of explosions of small nuclear charges;

Thermonuclear rocket engines that can use an isotope of hydrogen as fuel. The energy efficiency 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 pressure sunlight(solar wind), whose existence empirically proved 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 liquid propellant rocket engines is associated with the limited velocity of the outflow 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 principle of operation of nuclear rocket engines is almost the same as the principle of operation of thermochemical engines. The difference lies in the fact that the working fluid is heated not due to its own chemical energy, but due to the "foreign" energy released during the intranuclear reaction. The working fluid is passed through a nuclear reactor, in which the fission reaction of atomic nuclei (for example, uranium) takes place, and at the same time it heats up. 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 a large traction force. Hydrogen satisfies this condition most fully, 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 the so-called isotopic energy sources. The specific mass energy (the energy that a substance weighing 1 kg can release) of artificial radioactive isotopes is much higher than that of chemical fuels. Thus, for 210Ро 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 the difficulty of operation. After all, the isotope releases energy constantly, even when it is transported in a special container and when the rocket is parked at the start. Nuclear reactors use more energy efficient fuel. Thus, the specific mass energy of 235U (the fissile isotope of uranium) is 6.75 * 10 9 kJ / kg, that is, approximately an order of magnitude higher than that of the 210Ро isotope. These engines can be "turned on" and "off", nuclear fuel (233U, 235U, 238U, 239Pu) is much cheaper than isotope. 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 circuit nuclear rocket engine with a reactor running on solid nuclear fuel, the working fluid is placed in the tank. The pump delivers it to the engine chamber. Sprayed with the help of nozzles, the working fluid comes into contact with the heat-producing nuclear fuel, heats up, expands and is ejected outward through the nozzle at high speed. Nuclear fuel in terms of energy reserves surpasses any other type of fuel. Then a natural question arises - why do installations on this fuel still have a relatively small 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 emits strong ionizing radiation during operation, which has a harmful effect on living organisms. Biological protection against such radiation is of great importance and is not applicable to spacecraft. Practical developments nuclear rocket engines using solid nuclear fuel were launched in the mid-1950s in the Soviet Union and the United States, almost simultaneously with the construction of the first nuclear power plants. The work was carried out in an atmosphere of high secrecy, but it is known that such rocket engines have not yet received real use in astronautics. So far, everything has been limited to the use of isotopic sources of electricity of relatively low power on unmanned artificial satellites of the Earth, interplanetary spacecraft and the world-famous Soviet "lunar rover".

7. Nuclear jet engines, principle of operation, methods for obtaining an impulse in a nuclear rocket engine.

NRE got its 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 the transformation of some nuclei into others, associated with the rearrangement 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 artificially induced, for example, when some nuclei are bombarded by others (or by elementary particles). Nuclear reactions of fission and fusion in terms of energy exceed chemical reactions by millions and tens of millions of times, 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 power 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 the LRE, the original working fluid of the NRE is stored in a liquid state in the tank of the propulsion system and is supplied using a turbopump unit. Gas for the rotation of 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 NREs with a fission reactor:

solid phase

gas phase

NRE with fusion reactor

Pulse YARD and others

Of all the possible types of NRE, the most developed are the thermal radioisotope engine and the engine with a solid-phase fission reactor. But if the characteristics of radioisotope NREs do not allow us to hope for their wide application in astronautics (at least in the near future), then the creation of solid-phase NREs opens up great prospects for astronautics. A typical NRE 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 an active zone; a reflector surrounding this zone; governing bodies; power case and other elements. The core contains nuclear fuel - fissile material (enriched uranium), enclosed 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 placed 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 the solid-phase reactor are pierced with channels through which the working fluid of the NRE 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 core. The core is suspended by a special grid inside the power housing so that it can expand when the reactor is heated (otherwise it would collapse due to thermal stresses).

The core experiences high mechanical loads associated with the action of 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 core during heating of the reactor reaches several centimeters. The active zone and the reflector are placed inside a strong power housing, which perceives the pressure of the working fluid and the thrust created by the jet nozzle. The case is closed by a strong cover. It accommodates pneumatic, spring or electric mechanisms for driving the regulatory bodies, attachment points for the NRE to the spacecraft, flanges for connecting the NRE with the supply pipelines of the working fluid. A turbopump unit can also be located on the cover.

8 - Nozzle,

9 - Expanding nozzle,

10 - Selection of the working substance to the turbine,

11 - Power Corps,

12 - Control drum

13 - Turbine exhaust (used to control attitude and increase thrust),

14 - Ring drives control drums)

At the beginning of 1957, the final direction of the work of 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 (development of individual TNRE units). On behalf of the Los Alamos Laboratory, all special orders for the manufacture of individual components were carried out by the firms: Aerojet General, the Rocketdyne division of North American Aviation. In the summer of 1958, all control of the Rover program passed from the US 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 middle of the summer of 1960, the Office of Space Nuclear Engines was formed under the leadership of G. Finger, which led the Rover program in the future.

The results of six "hot tests" of nuclear jet engines were very encouraging, and in early 1961 a report on reactor flight tests (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 as the subcontractor responsible for the construction of the reactor.

10.2 TNRD work in Russia

American" href="/text/category/amerikanetc/" rel="bookmark">Americans Russian scientists used the most economical and efficient testing of individual fuel elements in research reactors. The whole range of work performed in the 70-80s made it possible in the Salyut Design Bureau, the Chemical Automation Design Bureau, the IAE, NIKIET and NPO Luch (PNITI) to develop various projects of space NREs and hybrid nuclear power plants. In the Design Bureau of Chemical Automation, under the scientific leadership of NIITP (the IPPE, IAE, NIKIET, NIITVEL, NPO Luch, MAI were responsible for the elements of the reactor), YARD RD 0411 and a nuclear engine of minimum dimension RD 0410 thrust of 40 and 3.6 tons, respectively.

As a result, a reactor, a “cold” engine, and a bench prototype for testing on gaseous hydrogen were manufactured. 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 fuel elements and high temperature in the core, had this indicator equal to 9100 m/s and higher. The bench base for testing the TNRD of the joint expedition of NPO Luch was located 50 km southwest of the city of Semipalatinsk-21. She began working in 1962. In the years full-scale fuel elements of NRE prototypes were tested at the test site. At the same time, the exhaust gas entered the closed emission system. The bench complex for full-scale testing of nuclear engines "Baikal-1" is located 65 km south of the city 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 at a hydrogen flow rate of up to 16.5 kg / s and its temperature at the reactor outlet of 3100 K. All launches were successful, accident-free, and according to plan.

Soviet TYARD RD-0410 - the only working and reliable industrial nuclear rocket engine in the world

Currently, such work at the landfill has been stopped, although the equipment is maintained in a relatively operable condition. The bench base of NPO Luch is the only experimental complex in the world where it is possible to test elements of NRE reactors without significant financial and time costs. It is possible that the resumption in the United States of work on TNRE for flights to the Moon and Mars as part of the Space Research Initiative program with the planned participation of specialists from Russia and Kazakhstan will lead to the resumption of the activities of the Semipalatinsk base and the implementation of the "Martian" expedition in the 2020s .

Main characteristics

Specific impulse on hydrogen: 910 - 980 sec(theor. up to 1000 sec).

· Speed of the expiration of a working body (hydrogen): 9100 - 9800 m/sec.

· Achievable thrust: up to hundreds and thousands of tons.

· Maximum working temperatures: 3000°С - 3700°С (short-term inclusion).

· Service life: up to several thousand hours (periodic activation). /5/

11.Device

The device of the Soviet solid-phase nuclear rocket engine RD-0410

1 - line from the tank of the working fluid

2 - turbopump unit

3 - control drum drive

4 - radiation protection

5 - control drum

6 - retarder

7 - fuel assembly

8 - reactor vessel

9 - fire bottom

10 - Nozzle cooling line

11- nozzle chamber

12 - nozzle

12. Working principle

The TNRD, according to its principle of operation, is a high-temperature reactor-heat exchanger, into which the working fluid (liquid hydrogen) is introduced under pressure, and as it is heated to high temperatures(over 3000°C) is ejected through a cooled nozzle. Heat recovery in the nozzle is very beneficial, as it allows much faster heating of hydrogen and, by utilizing a significant amount of thermal energy, to increase the specific impulse to 1000 sec (9100-9800 m/s).

Nuclear rocket engine reactor

MsoNormalTable">

working body

Density, g/cm3

Specific thrust (at the indicated temperatures in the heating chamber, °K), sec

0.071 (liquid)

0.682 (liquid)

1,000 (liquid)

No. data

(Note: The pressure in the heating chamber is 45.7 atm, expansion to a pressure of 1 atm at a constant chemical composition working body) /6/

15.Advantages

The main advantage of TNRD over chemical rocket engines is to obtain a higher specific impulse, a significant energy reserve, a compact system and the ability to obtain very high thrust (tens, hundreds and thousands of tons in vacuum. In general, the specific impulse achieved in 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 heat intensity by 4-5 times.At present, in the USA and Russia there is considerable 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 TNRD 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 the study of the solar system are significantly expanding, and the time required to reach the distant planets is significantly reduced. In addition, TNRD can be successfully used for vehicles operating in low orbits of giant planets using their rarefied atmosphere as a working fluid, or for working in their atmosphere. /8/

16. Disadvantages

The main disadvantage of TNRD is the presence of a powerful flux 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, TNRD 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 the TJARD. Hybrid TNRD

Like any rocket or any engine in general, a solid-phase nuclear jet engine has significant limitations on the achievable the most important characteristics. These restrictions represent the impossibility of the device (TNRD) to work in the temperature range exceeding the range of maximum operating temperatures of the engine structural materials. To expand the capabilities and significantly increase the main operating parameters of the TNRD, various hybrid schemes can be applied in which the TNRD plays the role of a source of heat and energy and additional physical methods for accelerating the working bodies are used. The most reliable, practically feasible, and having high characteristics in terms of specific impulse and thrust 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 YARD.

A working NRE 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 the spacecraft, embrittlement of metal structural materials, destruction of plastic and aging of rubber parts, violation of 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 NRE is considered to be solved in principle. The fundamental issues related to the maintenance of nuclear rocket engines on test benches and launch sites have also been resolved. Although a working YARD poses a danger to service personnel"Already a day after the end of the work of the NRE, it is possible, without any personal protective equipment, to stay for several tens of minutes at a distance of 50 m from the NRE and even approach it. The simplest means of protection allow maintenance personnel to enter the working area of the NRE soon after testing.

The level of contamination of launch complexes and environment, apparently, will not be an obstacle to the use of NREs on the lower stages of space rockets. The problem of radiation hazard to 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 NRE jet is no more dangerous than the LRE jet. / 4 /

Conclusion

When considering the prospects for the development and use of nuclear rocket engines in astronautics, one should proceed from the achieved and expected characteristics various types NRE, from what can give them to astronautics, their application, and, finally, from the presence of a close connection between the problem of NRE and the problem of energy supply in space and with the development of energy in general.

As mentioned above, of all the possible types of NRE, the most developed are the thermal radioisotope engine and the engine with a solid-phase fission reactor. But if the characteristics of radioisotope NREs do not allow us to hope for their wide application in astronautics (at least in the near future), then the creation of solid-phase NREs opens up great prospects for astronautics.

For example, a device with an initial mass of 40,000 tons (i.e., approximately 10 times greater than that of the largest modern launch vehicles) has been proposed, with 1/10 of this mass falling on the payload, and 2/3 on nuclear charges . If every 3 seconds one charge is blown up, then their supply will be enough for 10 days of continuous operation of the nuclear rocket engine. 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 practically unlimited energy intensity, independence of operation from the environment, non-susceptibility to external influences (cosmic radiation, meteorite damage, high and low temperatures, etc.). However maximum power nuclear radioisotope installations is limited to a value of the order of several hundred watts. This restriction does not exist for nuclear reactor power plants, which predetermines the profitability of their use during long-term flights of heavy spacecraft in near-Earth space, during flights to distant planets of the solar system, and in other cases.

The advantages of solid-phase and other NREs 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 RD makes it possible to solve qualitatively new problems. All these problems are greatly facilitated by the use of a solid-phase NRE with a specific impulse twice that of modern LREs. In this case, it also becomes possible to significantly reduce flight times.

Most likely, in the near future, solid-phase NREs will become one of the most common RDs. The solid-phase NRE can be used as vehicles for long-range flights, for example, to such planets as Neptune, Pluto, and even fly out of the Solar System. However, for flights to the stars, the NRE, based on the principles of fission, is not suitable. In this case, NREs or, more precisely, thermonuclear jet engines (TRDs) operating on the principle of fusion reactions and photonic jet engines (PRDs), in which the annihilation reaction of matter and antimatter is the source of momentum, are promising. However, most likely humanity to travel in interstellar space will use a different, different from the jet, method of movement.

In conclusion, I will rephrase Einstein's famous phrase - in order 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: Knowledge, 1999.
2. http://www. lpre. de/energomash/index. htm
3. Pervushin "Battle for the stars. Space confrontation" - M: knowledge, 1998.
4. L. Gilberg "Conquest of the sky" - M: Knowledge, 1994.
5. http://epizodsspace. *****/bibl/molodtsov
6. "Engine", "Nuclear engines for space vehicles", No. 5, 1999

7. "Engine", "Gas-phase nuclear engines for space vehicles",

No. 6, 1999
7.http://www. *****/content/numbers/263/03.shtml
8.http://www. lpre. de/energomash/index. htm
9. http://www. *****/content/numbers/219/37.shtml
10., Chekalin transport of the future.

Moscow: 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.

14., Sergeyuk and commerce. - M .: APN, 1989.

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
























	NERVA/Lox Mixed Cycle

Russia has been and still remains a leader in the field of nuclear space energy. Organizations such as RSC Energia and Roskosmos have experience in designing, building, launching and operating spacecraft equipped with a nuclear power source. The nuclear engine allows the exploitation aircrafts many years, repeatedly increasing their practical suitability.

historical chronicle

At the same time, the delivery of a research apparatus to the orbits of the distant planets of the solar system requires an increase in the resource of such a nuclear installation to 5-7 years. It has been proved that a complex with a nuclear propulsion system with a power of about 1 MW as part of a research spacecraft will allow for accelerated delivery of artificial satellites of the most distant planets, planetary rovers to the surface of natural satellites of these planets and delivery of soil from comets, asteroids, Mercury and satellites of Jupiter and Saturn.

Reusable tug (MB)

One of the most important ways to improve efficiency transport operations in space is the reusable use of elements of the transport system. A nuclear engine for spacecraft with a power of at least 500 kW makes it possible to create a reusable tug and thereby significantly increase the efficiency of a multi-link space transport system. Such a system is especially useful in a program to ensure large annual cargo flows. An example would be the Moon exploration program with the creation and maintenance of a constantly growing habitable base and experimental technological and industrial complexes.

Calculation of cargo turnover

According to the design studies of RSC Energia, during the construction of the base, modules with a mass of about 10 tons should be delivered to the lunar surface, up to 30 tons into the lunar orbit. The total cargo flow from the Earth during the construction of a habitable moon base and the visited lunar orbital station is estimated at 700-800 tons, and the annual cargo flow to ensure the functioning and development of the base is 400-500 tons.

However, the principle of operation of a nuclear engine does not allow to disperse the transporter quickly enough. Due to the long time of transportation and, accordingly, the significant time spent by the payload in the radiation belts of the Earth, not all cargo can be delivered using nuclear-powered tugs. Therefore, the cargo flow that can be ensured on the basis of NEP is estimated at only 100-300 tons/year.

Economic efficiency

As a criterion for the economic efficiency of the interorbital transport system, it is advisable to use the value of the unit cost of transporting a unit mass of payload (PG) from the Earth's surface to the target orbit. RSC Energia developed an economic and mathematical model that takes into account the main cost components in the transport system:

for the creation and launch of tug modules into orbit;
for the purchase of a working nuclear installation;
operating costs, as well as R&D costs and possible capital costs.

Cost indicators depend on the optimal parameters of the MB. Using this model, a comparative economic efficiency the use of a reusable tug based on nuclear propulsion systems with a capacity of about 1 MW and a disposable tug based on advanced liquid propellant ones in the program to ensure the delivery of a payload with a total mass of 100 t/year from the Earth to the lunar orbit with a height of 100 km. When using the same launch vehicle with a carrying capacity equal to the carrying capacity of the Proton-M launch vehicle and a two-launch scheme for constructing a transport system, the unit cost of delivering a unit mass of payload using a tug based on a nuclear engine will be three times lower than when using disposable tugboats based on rockets with liquid engines of the DM-3 type.

Conclusion

An efficient nuclear engine for space contributes to the solution of environmental problems of the Earth, manned flight to Mars, the creation of a wireless power transmission system in space, the implementation of high-safety disposal in space of highly hazardous ground-based radioactive waste. nuclear energy, the creation of a habitable lunar base and the beginning of the industrial development of the moon, ensuring the protection of the Earth from asteroid-comet hazard.

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 rocket, the testimony during the annual message of the President, aroused the blogger's lively interest. And here's what he found on the subject.

Yes, historically there have been developments of cruise missiles with a ramjet nuclear air engine: this is the SLAM missile in the USA with the TORY-II reactor, the Avro Z-59 concept in the UK, and developments in the USSR.

A modern rendering of the Avro Z-59 rocket concept, weighing about 20 tons.

However, all these works went on in the 60s as R&D of varying degrees of depth (the United States went the farthest, as discussed below) and were not continued in the form of samples in service. They didn’t get it for the same reason as many other Atom Age developments - planes, trains, rockets with nuclear power plants. All these options Vehicle with some pluses that the frantic energy density in nuclear fuel gives, they have very serious disadvantages - high cost, complexity of operation, requirements for constant protection, and finally, unsatisfactory development results, about which little is usually known (by publishing R&D results, it is more profitable for all parties to exhibit achievements and hide failures ).

In particular, it is much easier for cruise missiles to create a carrier (submarine or aircraft) that will "drag" a lot of missiles to the launch site than to fool around with a small fleet (and it is incredibly difficult to master a large fleet) of cruise missiles launched from one's own territory. A universal, cheap, mass product won in the end a small-scale, expensive and with ambiguous pluses. Nuclear cruise missiles did not go beyond ground tests.

This conceptual dead end of the 60s of the KR with nuclear power plants, in my opinion, is still relevant now, so the main question to the shown one is "why ??". But it is made even more convex by the problems that arise in the development, testing and operation of such weapons, which we will talk about further.

So let's start with the reactor. The SLAM and Z-59 concepts were three-machine low-flying rockets of impressive dimensions and mass (20+ tons after the launch boosters were dropped). The terribly costly low-flying supersonic made it possible to make the most of the presence of a practically unlimited source of energy on board, in addition, important feature nuclear air jet engine is work efficiency improvements (thermodynamic cycle) with increasing speed, i.e. the same idea, but at speeds of 1000 km / h would have a much heavier and overall engine. Finally, 3M at a height of a hundred meters in 1965 meant invulnerability to air defense. It turns out that earlier the concept of missile launchers with nuclear power plants was “tied up” at high speed, where the advantages of the concept were strong, and competitors with hydrocarbon fuel were weakening. The rocket shown, in my opinion look, transonic or slightly supersonic (unless, of course, you believe that it is she on the video). But at the same time, the size of the reactor decreased significantly compared to TORY II from the SLAM rocket, where it was as much as 2 meters including a graphite radial neutron reflector

Is it even possible to lay a reactor with a diameter of 0.4-0.6 meters?

Let's start with a fundamentally minimal reactor - a blank of Pu239. Good example implementation of such a concept is the Kilopower space reactor, where, however, U235 is used. The diameter of the reactor core is only 11 centimeters! If you switch to plutonium 239, the dimensions of the core will drop by another 1.5-2 times. Now from minimum size we will begin to walk 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 a U or Pu blank - they will simply burn out in an air stream in just a minute. A sheath is needed, such as incaloy, which resists instantaneous oxidation up to 1000 C, or other nickel alloys with a possible ceramic coating. Application a large number the material of the shells in the core immediately increases the required amount of nuclear fuel by several times - after all, the "unproductive" absorption of neutrons in the core has now increased dramatically!

Moreover, the metallic form of U or Pu is no longer suitable - these materials themselves are not refractory (plutonium generally melts at 634 C), but they also interact with the material of metal shells. We convert the fuel into the classical form of UO2 or PuO2 - we get one more dilution of the material in the core, now with oxygen.

Finally, we recall 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 core diameter grows to 40-50 cm (for uranium), and the diameter of the reactor with a 10-cm beryllium reflector up to 60-70 cm. MITEE designed for flights in Jupiter's atmosphere. This one is completely paper project(for example, the temperature of the core is provided at 3000 K, and the walls are made of beryllium, which can withstand a force of 1200 K) has a diameter of the core calculated from neutronics of 55.4 cm, while cooling with hydrogen makes it possible to slightly reduce the size of the channels through which the coolant is pumped.

In my opinion, an air nuclear jet engine can be pushed into a rocket with a diameter of about a meter, which, however, is still not cardinally larger than the voiced 0.6-0.74 m, but still alarming. One way or another, the nuclear power plant will have a power of ~ several megawatts, powered by ~10^16 disintegrations per second. This means that the reactor itself will create a radiation field of several tens of thousands of roentgens near the surface, and up to a thousand roentgens along the entire rocket. Even the installation of several hundred kg of sector protection will not greatly reduce these levels, because. neutrons and gamma quanta 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. The background from the structure itself can reach tens of x-rays at a distance of 10 meters from the rocket body.

All these "gaiety" give the idea that the development and testing of such a missile 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 rather complex way (radiation, temperature, vibrations - and all this for statistics). Flight tests with a working reactor at any moment can turn into a radiation catastrophe with a release from hundreds of terrabecquerels to units of petabecquerels. Even without catastrophic situations, the depressurization of individual fuel rods and the release of radionuclides are very likely.

Of course, in Russia there are still Novaya Zemlya polygon on which such tests can be carried out, but this would be contrary to the spirit of the treaty on nuclear test ban in three environments (The ban was introduced to prevent systematic pollution of the atmosphere and the ocean with radionuclides).

Today NIKIET has a team of designers who perform work on the design of reactors ( high-temperature gas-cooled RUGK , fast reactors MBIR, ), while IPPE and Luch continue to deal with related calculations and technologies, respectively. The Kurchatov Institute, in recent decades, has moved more towards the theory of nuclear reactors.

In summary, I would like to say that the creation of a cruise missile with air-jet engines with nuclear power plants is generally a feasible task, but at the same time extremely expensive and complex, requiring significant mobilization of human and financial resources, as it seems to me, to a greater extent than all other voiced projects ("Sarmat", "Dagger", "Status-6", "Vanguard"). It is very strange that this mobilization did not leave the slightest trace. And most importantly, it is not at all clear what is the benefit of obtaining such types of weapons (against the background of existing carriers), and how they can outweigh the numerous disadvantages - issues of radiation security, high cost, incompatibility with strategic arms reduction treaties.

P.S. However, the "sources" are already beginning to soften the situation: "A source close to the military-industrial complex said" Vedomosti ”, that radiation safety during missile testing was ensured. nuclear plant on board presented an electrical mock-up, the source says.

About a cruise missile with "unlimited range due to a super-powerful nuclear power plant" in the dimensions of Tomahawk cruise missiles (0.53 m in diameter and weighing 1400 kg) or Kh-101 (0.74 m in diameter and weighing 2300 kg).

Soviet prototype RD-0410(GRAU index - 11B91, also known as "Irgit" and "IR-100") - the first and only Soviet nuclear rocket engine

Let's start with a video presentation of GDP

Summarizing the sensations from the shown project, we can say that this is an extreme surprise on the verge of unreliability of the shown. I'll try to explain why.

A modern rendering of the Avro Z-59 rocket concept, weighing about 20 tons.

However, all these works went on in the 60s as R&D of varying degrees of depth (the United States went the farthest, as discussed below) and did not receive continuation in the form of models in service. They didn’t get it for the same reason as many other Atom Age developments - planes, trains, rockets with nuclear power plants. All these vehicle options, with some advantages that the frantic energy density in nuclear fuel gives, have very serious disadvantages - high cost, complexity of operation, requirements for constant protection, and finally, unsatisfactory development results, about which little is usually known (publishing R&D results is more profitable for all parties expose achievements and hide failures).

In particular, for cruise missiles it is much easier to create a carrier (submarine or aircraft) that will "drag" a lot of cruise missiles to the launch site than to fool around with a small fleet (and it is incredibly difficult to master a large fleet) of cruise missiles launched from one's own territory. A universal, cheap, mass product won in the end a small-scale, expensive and with ambiguous pluses. Nuclear cruise missiles did not go beyond ground tests.

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 shown one is "why??". But it is made even more convex by the problems that arise in the development, testing and operation of such weapons, which we will talk about further.

It turns out that before the concept of CR with nuclear power plants 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, is transonic or weakly supersonic (unless, of course, you believe that it is she in the video). But at the same time, the size of the reactor decreased significantly compared to the TORY-II from the SLAM rocket, where it was as much as 2 meters, including a radial neutron reflector made of graphite

The core of the first TORY-II-A test reactor during assembly.

Is it even possible to lay a reactor with a diameter of 0.4-0.6 meters? Let's start with a fundamentally minimal reactor - a blank of Pu239. 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 dimensions 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 complexity. 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 a U or Pu blank - they will simply burn out in an air stream in just a minute. A sheath is needed, such as incaloy, which resists instantaneous 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 immediately increases the required amount of nuclear fuel by several times - after all, the "unproductive" absorption of neutrons in the core has now increased dramatically!

Finally, we recall the purpose of the reactor. We need to pump a lot of air through it, to which we will give off heat. about 2/3 of the space will be occupied by "air tubes".

TORY-IIC. The fuel rods in the active zone are hexagonal hollow tubes made of UO2, covered with a protective ceramic shell, assembled in incalo fuel assemblies.

As a result, the minimum core diameter grows to 40-50 cm (for uranium), and the diameter of the reactor with a 10-cm beryllium reflector up to 60-70 cm. Jupiter. This completely paper project (for example, the temperature of the core is provided at 3000 K, and the walls are made of beryllium, which can withstand a force of 1200 K) has a diameter of the core calculated from neutronics of 55.4 cm, while cooling with hydrogen makes it possible to slightly reduce the size of the channels through which the coolant is pumped .

The cross section of the active zone of the MITEE atmospheric jet nuclear engine and the minimum achievable masses for various variants of the core geometry - in brackets are the ratios of the length to the fuel rod pitch (first digit), the number of fuel rods (second digit), the number of reflector elements (tertiary digit) for different compositions. The option with fuel in the form of Americium 242m and a liquid hydrogen reflector is not without interest :)

In my opinion, an air nuclear jet engine can be pushed into a rocket with a diameter of about a meter, which, incidentally, is still not cardinally larger than the voiced 0.6-0.74 m, but still alarming.

One way or another, the nuclear power plant will have a power of ~several megawatts, powered by ~10^16 disintegrations per second. This means that the reactor itself will create a radiation field of several tens of thousands of roentgens near the surface, and up to a thousand roentgens along the entire rocket. Even the installation of several hundred kg of sector protection will not greatly reduce these levels, because. neutrons and gamma quanta 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. The background from the structure itself can reach tens of x-rays at a distance of 10 meters from the rocket body.

X-ray of the SLAM rocket. All drives are pneumatic, the control equipment is in a capsule that attenuates radiation.

Of course, in Russia there is still a Novaya Zemlya test site where such tests can be carried out, but this will be contrary to the spirit of the treaty banning nuclear weapons tests in three environments (the ban was introduced to prevent systematic contamination of the atmosphere and ocean with radionuclides).

Finally, it is interesting who in the Russian Federation could develop such a reactor. Traditionally, the Kurchatov Institute (general design and calculations), the Obninsk FEI (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 joined the design of such machines (for example, the IGR and IVG reactors - prototypes of the active zone of the RD-0410 nuclear rocket engine). Today, NIKIET has a team of designers who carry out work on the design of reactors (high-temperature gas-cooled RUGK, fast reactors MBIR, ), and IPPE and Luch continue to deal with related calculations and technologies, respectively. The Kurchatov Institute, in recent decades, has moved more towards the theory of nuclear reactors.

The closest relatives of air NREs are space NREs purged with hydrogen.

In summary, I would like to say that the creation of a cruise missile with air-jet engines with nuclear power plants is, on the whole, a feasible task, but at the same time extremely expensive and complex, requiring significant mobilization of human and financial resources, as it seems to me, to a greater extent than all other voiced projects (" Sarmat", "Dagger", "Status-6", "Vanguard"). It is very strange that this mobilization did not leave the slightest trace. And most importantly, it is not at all clear what is the benefit of obtaining such types of weapons (against the background of existing carriers), and how they can outweigh the numerous disadvantages - issues of radiation security, high cost, incompatibility with strategic arms reduction treaties.

P.S. However, the "sources" are already beginning to soften the situation: "A source close to the military-industrial complex told Vedomosti that radiation safety during missile testing was ensured. The nuclear installation on board was an electric mock-up, the source says."

RD-0410

In RD-0410, a heterogeneous thermal neutron reactor was used, zirconium hydride served as a moderator, neutron reflectors were made of beryllium, nuclear fuel was a material based on uranium and tungsten carbides, enriched in the 235 isotope about 80%. The design included 37 fuel assemblies covered with thermal insulation separating 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 the full duration of operation. The extra-reactor nodes were fully worked out.

Extremely interesting video:

Quite a few interesting things are shown. Apparently, the video was made in the late 80s for internal Minsredmashevsky / Minsredmashevsky use, and in the early 90s English subtitles were inserted there in order to interest Americans in technology.