The experience gained in the 50-70s of the XX century will still be useful in the XXI century
It may seem strange that nuclear power, which is firmly rooted in the earth, in the hydrosphere, and even in space, has not taken root in the air. This is the case when apparent safety considerations (although not only them) outweighed the obvious technical and operational benefits from the introduction of nuclear power plants (NPS) in aviation.
Meanwhile, the likelihood of severe consequences of incidents with such aircraft, provided they are perfect, can hardly be regarded as higher in comparison with space systems using nuclear power plants (NPP). And for the sake of objectivity, it is worth recalling: the accident of the Soviet artificial earth satellite Kosmos-954 of the US-A type, which occurred in 1978 with the fall of its fragments into the territory of Canada, which occurred in 1978, did not lead to the curtailment of the maritime space reconnaissance and target designation system. (MKRTs) "Legend", the element of which was the US-A (17F16-K) devices.
On the other hand, the operating conditions of an aviation nuclear power plant designed to create thrust by generating heat in a nuclear reactor supplied to the air in a gas turbine engine are completely different from those of satellite nuclear power plants, which are thermoelectric generators. Today, two schematic diagrams of an aviation nuclear control system have been proposed - an open and a closed type. The open-type scheme provides for the heating of the compressed air by the compressor directly in the reactor channels with its subsequent outflow through the jet nozzle, and the closed type provides for heating the air using a heat exchanger, in a closed loop of which the coolant circulates. The closed circuit can be one- or two-circuit, and from the point of view of ensuring operational safety, the second option looks the most preferable, since the reactor block with the first circuit can be placed in a protective shockproof shell, the tightness of which prevents catastrophic consequences in case of aircraft accidents.
In closed-type aviation nuclear systems, pressurized water reactors and fast neutron reactors can be used. When implementing a two-circuit scheme with a "fast" reactor in the first circuit of the NPS, both liquid alkali metals (sodium, lithium) and an inert gas (helium) would be used as a coolant, and in the second, alkali metals (liquid sodium, eutectic sodium melt, etc.) potassium).
IN AIR - REACTOR
The idea to use nuclear energy in aviation was put forward in 1942 by one of the leaders of the Manhattan Project, Enrico Fermi. She became interested in the command of the US Air Force, and in 1946 the Americans embarked on the NEPA (Nuclear Energy for the Propulsion of Aircraft) project, designed to determine the possibilities of creating an unlimited-range bomber and reconnaissance aircraft.
First of all, it was necessary to conduct research related to the anti-radiation protection of the crew and ground service personnel, and to give a probabilistic-situational assessment of possible accidents. In order to speed up the work, the NEPA project in 1951 was expanded by the US Air Force to the target program ANP (Aircraft Nuclear Propulsion). Within its framework, General Electric was developing an open circuit, and Pratt-Whitney was developing a closed NPS circuit.
For testing the future aviation nuclear reactor (exclusively in the mode of physical launches) and biological protection, the serial B-36H Peacemaker strategic bomber of the Convair company was intended with six piston and four turbojet engines. It was not a nuclear aircraft, but was just a flying laboratory, where the reactor was to be tested, but was designated NB-36H - Nuclear Bomber ("Atomic bomber"). The cockpit was transformed into a lead and rubber capsule with an additional steel and lead shield. To protect against neutron radiation, special panels filled with water were inserted into the fuselage.
The prototype aircraft reactor ARE (Aircraft Reactor Experiment), created in 1954 by the Oak Ridge National Laboratory, became the world's first homogeneous nuclear reactor with a capacity of 2.5 MW on fuel from a molten salt - sodium fluoride and zirconium and uranium tetrafluorides.
The advantage of this type of reactors lies in the fundamental impossibility of an accident with the destruction of the core, and the fuel salt mixture itself, in the case of a closed-type aviation NSU, would act as a primary coolant. When a molten salt is used as a coolant, the higher, in comparison, for example, with liquid sodium, the heat capacity of the molten salt makes it possible to use circulating pumps of small dimensions and to benefit from a decrease in the metal consumption of the structure of the reactor plant as a whole, and the low thermal conductivity should have ensured the stability of the nuclear aircraft engine against sudden temperature jumps. in the first circuit.
On the basis of the ARE reactor, the Americans have developed an experimental aviation YSU HTRE (Heat Transfer Reactor Experiment). Without further ado, General Dynamics designed the X-39 aircraft nuclear engine based on the serial J47 turbojet engine for the strategic bombers B-36 and B-47 “Stratojet” - instead of a combustion chamber, the reactor core was placed in it.
Convair intended to supply the X-39 to the X-6 - perhaps its prototype would be the B-58 Hustler supersonic strategic bomber, which made its maiden flight in 1956. In addition, the atomic version of an experienced subsonic bomber of the same YB-60 company was also considered. However, the Americans abandoned the open-circuit aviation nuclear control system, considering that the erosion of the walls of the air channels of the X-39 reactor core will lead to the fact that the aircraft will leave behind a radioactive trail, polluting the environment.
The hope for success was promised by the more radiation-safe closed-type nuclear power plant of the Pratt-Whitney company, to the creation of which General Dynamics was also involved. For these engines, the company "Convair" began the construction of experimental aircraft NX-2. Both turbojet and turboprop versions of nuclear bombers with nuclear power plants of this type were being worked out.
However, the adoption in 1959 of the Atlas intercontinental ballistic missiles, capable of striking targets in the USSR from the continental United States, neutralized the ANP program, especially since production samples of atomic aircraft would hardly have appeared before 1970. As a result, in March 1961, all work in this area in the United States was stopped by the personal decision of President John F. Kennedy, and a real atomic plane was never built.
The flight sample of the aircraft reactor ASTR (Aircraft Shield Test Reactor), located in the bomb compartment of the NB-36H flying laboratory, was a 1 MW fast neutron reactor that was not connected to the engines and operated on uranium dioxide and cooled by a stream of air taken through special air intakes. From September 1955 to March 1957, the NB-36H made 47 flights with ASTR over uninhabited areas of the states of New Mexico and Texas, after which the car was never lifted into the sky.
It should be noted that the US Air Force also dealt with the problem of a nuclear engine for cruise missiles or, as it was customary to say until the 1960s, for projectile aircraft. As part of the Pluto project, Livermore Laboratory created two samples of the Tory nuclear ramjet engine, which was planned to be installed on the SLAM supersonic cruise missile. The principle of "atomic heating" of air by passing through the reactor core was here the same as in open-type nuclear gas turbine engines, with only one difference: the ramjet engine lacks a compressor and a turbine. Tories, successfully tested on the ground in 1961-1964, are the first and so far the only really operating aviation (more precisely, missile and aviation) nuclear power plants. But this project was also closed as hopeless against the background of successes in the creation of ballistic missiles.
Catch up and overtake
Of course, the idea of using nuclear energy in aviation, independently of the Americans, also developed in the USSR. Actually, in the West, not without reason, they suspected that such work was being carried out in the Soviet Union, but with the first disclosure of the fact about them they got into a mess. On December 1, 1958, Aviation Week reported: The USSR is creating a strategic bomber with nuclear engines, which caused considerable excitement in America and even helped to maintain interest in the ANP program, which had already begun to fade away. However, in the drawings accompanying the article, the editorial artist quite accurately depicted the M-50 aircraft of the V. M. Myasishchev Experimental Design Bureau, which was actually being developed at that time, with a completely "futuristic" appearance, which had conventional turbojet engines. It is not known, by the way, whether this publication was followed by a "showdown" in the KGB of the USSR: work on the M-50 took place in an atmosphere of the strictest secrecy, the bomber made its first flight later than the mention in the Western press, in October 1959, and the car was presented to the general public only in July 1961 at the air parade in Tushino.
As for the Soviet press, for the first time about the atomic plane was told in the most general terms by the magazine "Technics - Youth" back in No. 8 for 1955: “Atomic energy is increasingly used in industry, energy, agriculture and medicine. But the time is not far off when it will be used in aviation. From the airfields, gigantic machines will easily rise into the air. Nuclear planes will be able to fly almost as long as you like, without sinking to the ground for months, making dozens of non-stop round-the-world flights at supersonic speed. " The magazine, hinting at the military purpose of the vehicle (civil aircraft do not need to be in the sky "as long as you like"), nevertheless presented a hypothetical scheme of a cargo-passenger airliner with an open-type nuclear power plant.
However, the Myasishchevsky collective, and not alone, did indeed deal with aircraft with nuclear power plants. Although Soviet physicists have been studying the possibility of their creation since the end of the 1940s, practical work in this direction in the Soviet Union started much later than in the United States, and they began with the decree of the Council of Ministers of the USSR No. 1561-868 of August 12, 1955. According to him, OKB-23 V. M. Myasishchev and OKB-156 A. N. Tupolev, as well as aircraft-engine OKB-165 A. M. Lyulka and OKB-276 N. D. Kuznetsov were tasked with developing atomic strategic bombers.
The aircraft nuclear reactor was designed under the supervision of Academicians I. V. Kurchatov and A. P. Aleksandrov. The goal was the same as that of the Americans: to get a car that, having taken off from the territory of the country, would be able to strike targets anywhere in the world (first of all, of course, in the USA).
A feature of the Soviet atomic aviation program was that it continued even when the topic was already forgotten in the United States.
When creating a nuclear power plant, we thoroughly analyzed the conceptual diagrams of the open and closed type. So, under the open-type scheme, which received the code "B", the Lyulka Design Bureau developed two types of atomic-turbojet engines - axial, with the passage of the turbocompressor shaft through an annular reactor, and "rocker arms" - with a shaft outside the reactor, located in a curved flow path. In turn, the Kuznetsov Design Bureau worked on the engines according to the closed "A" scheme.
The Myasishchev Design Bureau immediately set about solving the most, apparently, difficult task - to design atomic super-high-speed heavy bombers. Even today, looking at the diagrams of future cars made in the late 50s, one can definitely see the features of the technical aesthetics of the 21st century! These are the projects of aircraft "60", "60M" (atomic seaplane), "62" for Lyulkovsk engines of the "B" scheme, as well as "30" - already for engines of Kuznetsov. The expected characteristics of the "30" bomber are impressive: maximum speed - 3600 km / h, cruising speed - 3000 km / h.
However, the matter did not come to the detailed design of the Myasishchev nuclear aircraft due to the liquidation of OKB-23 in an independent capacity and its introduction into the rocket and space OKB-52 of V. N. Chelomey.
At the first stage of participation in the program, Tupolev's team was to create a flying laboratory similar in purpose to the American NB-36H with a reactor on board. Received the designation Tu-95LAL, it was built on the basis of the serial turboprop heavy strategic bomber Tu-95M. Our reactor, like the American one, was not mated with the engines of the carrier aircraft. The fundamental difference between the Soviet aircraft reactor and the American one was that it was water-moderated, with a much lower power (100 kW).
The domestic reactor was cooled by the water of the primary circuit, which in turn gave heat to the water of the secondary circuit, which was cooled by the flow of air running through the air intake. This was how the schematic diagram of the Kuznetsov NK-14A atomic turboprop engine was worked out.
The Tu-95LAL flying nuclear laboratory in 1961-1962 lifted the reactor into the air 36 times both in the operating and in the "cold" state in order to study the effectiveness of the biological protection system and the effect of radiation on the aircraft systems. According to the test results, the chairman of the State Committee for Aviation Technology P. V. Dementyev, however, noted in his note to the country's leadership in February 1962: with YSU was developed in OKB-301 S. A. Lavochkin. - K. Ch.), since the research work carried out is insufficient for the development of prototypes of military equipment, this work must be continued."
In development of the design reserve of OKB-156, the Tupolev Design Bureau developed on the basis of the Tu-95 bomber a project of an experimental Tu-119 aircraft with NK-14A atomic turboprop engines. Since the task of creating an ultra-long-range bomber with the appearance in the USSR of intercontinental ballistic missiles and sea-based ballistic missiles (on submarines) has lost its critical relevance, the Tupolevites considered the Tu-119 as a transitional model on the way to creating a nuclear anti-submarine aircraft based on the long-range passenger airliner Tu-114, which also "grew" from the Tu-95. This goal was quite consistent with the concern of the Soviet leadership about the deployment by the Americans in the 1960s of a submarine nuclear missile system with Polaris ICBMs and then Poseidon.
However, the project of such an aircraft was not implemented. Remained at the design stage and the plans for creating a family of Tupolev supersonic bombers with YSU under the code name Tu-120, which, like the atomic air hunter for submarines, were planned to be tested in the 70s …
Nevertheless, the Kremlin liked the idea of giving the naval aviation an anti-submarine aircraft with an unlimited flight range to combat NATO nuclear submarines in any region of the oceans. Moreover, this machine was supposed to carry as much ammunition as possible of anti-submarine weapons - missiles, torpedoes, depth charges (including nuclear) and sonar buoys. That is why the choice fell on the heavy military transport aircraft An-22 "Antey" with a carrying capacity of 60 tons - the world's largest wide-body turboprop airliner. It was planned to equip the future An-22PLO aircraft with four NK-14A atomic-turboprop engines instead of the standard NK-12MA.
The program for the creation of such an unseen in any other fleet of a winged machine received the code name "Aist", and the reactor for the NK-14A was developed under the leadership of Academician A. P. Aleksandrov. In 1972, testing of the reactor began on board the An-22 flying laboratory (a total of 23 flights), and a conclusion was made about its safety in normal operation. And in the event of a serious accident, it was envisaged to separate the reactor unit and the primary circuit from the falling aircraft with a soft landing by parachute.
In general, the aviation reactor "Aist" has become the most perfect achievement of nuclear science and technology in its field of application.
Considering that on the basis of the An-22 aircraft it was also planned to create an An-22R intercontinental strategic aviation missile system with an R-27 submarine ballistic missile, it is clear what a powerful potential such a carrier could receive if it were transferred to “atomic thrust” »With NK-14A engines! And although the implementation of the An-22PLO project and the An-22R project again did not come to fruition, it must be stated that our country has nevertheless overtaken the United States in the field of creating an aviation nuclear power plant.
There is no doubt that this experience, despite its exoticism, is still capable of being useful, but already at a higher quality level of implementation.
The development of unmanned ultra-long-range reconnaissance and strike aircraft systems may well follow the path of using nuclear systems on them - such assumptions are already being made abroad.
Scientists also predicted that by the end of this century, millions of passengers are likely to be transported by nuclear-powered passenger aircraft. In addition to the obvious economic benefits associated with replacing aviation kerosene with nuclear fuel, we are talking about a sharp decrease in the contribution of aviation, which, with the transition to nuclear power systems, will cease to “enrich” the atmosphere with carbon dioxide, to the global greenhouse effect.
In the author's opinion, aviation nuclear systems would perfectly fit into the commercial aviation-transport complexes of the future based on super-heavy cargo aircraft: for example, the same giant “air ferry” M-90 with a carrying capacity of 400 tons, proposed by the designers of the experimental machine-building plant named after V. M. Myasishchev.
Of course, there are problems in terms of changing public opinion in favor of nuclear civil aviation. Serious issues related to ensuring its nuclear and anti-terrorist security will also have to be resolved (by the way, experts mention the domestic solution with the parachute “shooting” of the reactor in the event of an emergency). But the road, beaten more than half a century ago, will be mastered by the walker.
