Relatively recently, fresh reports have emerged about this Russian-developed cruise missile, which is capable of carrying a nuclear payload; so far, nothing especially new. What is genuinely striking, however, is its alleged “nuclear propulsion”. As we shall see, this is not a wholly novel concept: it has been investigated before, and we will examine why it was ultimately abandoned.
Background to nuclear propulsion
There has always been considerable interest in harnessing nuclear energy which, mass for mass, is unquestionably far more efficient than any energy source provided by conventional fuel. It is therefore tempting to apply nuclear power to tasks with major energy demands, such as propulsion.
Examples of nuclear propulsion are not difficult to find today. Nuclear submarines and aircraft carriers already use nuclear reactors to generate the energy needed for propulsion, as well as for many other functions.
There are other precedents, however, including nuclear-powered aircraft (the Convair NB-36H), spacecraft (Project Orion) and, during the period of greatest enthusiasm for applying nuclear energy to everything, even proposals for tanks powered by nuclear reactors. Finally-and most relevant to this article-there were missiles, including Projects NERVA, Pluto and SLAM, among others.
As a result, this is not conceptually anything new. It is nevertheless worth looking more closely at how these systems work.
Nuclear propulsion in missiles
In the case of cruise missiles such as the Burevestnik, the technology is thought to be a ramjet system. It would use an initial stage to launch the missile and bring it up to operating speed, most likely a conventional chemical-fuel rocket acting as a booster, since this is theoretically the most suitable arrangement for ramjet engines.
A ramjet is an engine designed for supersonic flight and is distinguished by its relative simplicity. Compression is achieved solely through the geometry of the intake, unlike conventional aircraft engines, which employ fan-like compressors. At around Mach 5-five times the speed of sound-shock waves alone produce the necessary compression. This is why a ramjet has to be brought up to “operating speed”: at subsonic speeds, or at low supersonic speeds, it cannot generate sufficient compression.
So far, none of this represents an innovation. Hypersonic missiles using these technologies are already in service and have attracted considerable attention. The remaining question is how, once that air has been taken in, combustion can be created to provide propulsive energy. This is where the-not entirely-new element begins.
Project Pluto and the Tory engine
The development of a nuclear ramjet system began in the early 1960s. This provides a basis for drawing parallels with the Russian missile system. First, it is necessary to examine Project Pluto, part of the SLAM (Supersonic Low-Altitude Missile) system, which was intended to be a nuclear-capable cruise missile. Its key innovation lay in its propulsion arrangement: Project Pluto sought to create a nuclear ramjet called Tory.
Figure 1: Diagram of the TORY II-A engine test rig. Source: University of California, TORY II-A A Nuclear Ramjet Test Reactor, 1959.
The main design objective for the Tory engine was to make it sufficiently compact. This particular version measured 114.3 cm long and 81.3 cm in diameter. It used 500,000 pencil-shaped fuel elements, each with an outer beryllium oxide structure acting as a moderator and containing uranium-235. Together, they effectively formed a structure resembling a honeycomb.
Air entering the engine would come into direct contact with the walls of the fuel rods, allowing it to reach the required operating temperature of approximately 2500°C. Schematically, it would have been arranged as follows:
Figure 2: Cross-section of the TORY II engine. Source: University of California, TORY II-A A Nuclear Ramjet Test Reactor, 1959.
In essence, Tory produced 500 megawatts of power, used to drive the engine and therefore the SLAM system. Once development had progressed, testing began. Given the radioactive effects expected when starting the engine, an autonomous system was devised and a 3.2 km track was built for the trials. On 14 May 1961, the world saw the first nuclear ramjet: the Tory II-A engine. The Tory-II-C was subsequently developed and tested, operating continuously for 5 minutes and producing more than 35,000 pounds of thrust.
Despite these promising results, Project Pluto was eventually cancelled, principally because of the potential harm it could cause to US allies. Long before striking its payload target, a SLAM powered by TORY engines would irradiate everything along its route. In addition, intercontinental ballistic missile technology was already beginning to fulfil the missions envisaged for SLAM. Finally, in 1964, Project Pluto was terminated after costing $260 million[1].
Burevestnik
Originally announced in 2018 alongside other strategic weapons, the Burevestnik first entered the news in 2019. During tests of a “nuclear engine”, an accident killed 5 engineers and 2 military personnel, while a spike in radiation was detected in Severodvinsk. A recovery operation also took place involving several vessels, including one equipped with special protection against radiation from the engine core[2].
More recently, on 4 November, a test of this missile was officially announced. Its nuclear engine reportedly gives it a virtually unlimited range. Having flown for 14 hours and covered more than 14,000 kilometres, the test demonstrated the capability of this type of engine. Information on the missile remains fairly limited, and the fact that no abnormal radiation readings have yet been detected may indicate that Russia has perhaps resolved the issue encountered by the United States during Project Pluto.
It is crucial to note, however, that the missile does not currently appear to bring anything new to the strategic landscape. As with Project Pluto, its advantages over more conventional systems are not substantially greater. Instead, it may be regarded as a technology demonstrator or perhaps simply a show of force. Finally, the danger involved in defending against such a system should not be overlooked: in essence, it would be equivalent to destroying a nuclear power reactor, with all the well-known complications associated with accidents such as Chernobyl.
Effects on the international context
These tests of new nuclear-capable weapons form part of an international environment in which Russia withdrew from the CTBT (Comprehensive Test Ban Treaty) in 2023, thereby allowing itself to resume nuclear testing should it wish to do so. More recently, President Trump also announced that the United States would resume testing nuclear weapons, an action that could be interpreted as a response to Russian weapons trials, including the Burevestnik missile and the nuclear Poseidon torpedo. However, the United States has not yet formally withdrawn from the CTBT.
It should also be remembered that New START, the last nuclear weapons treaty between the two principal powers, Russia and the United States, is due to expire in February 2026. Once it ends, unless it is extended or replaced by a new agreement, neither state will have regulation or oversight of the other’s nuclear arsenal and delivery systems. Unfortunately, based on the circumstances outlined above, it appears unlikely that the parties will seek to renew an agreement that has placed a cap on deployed ballistic nuclear arsenals and certain specific weapons, such as the Avangard hypersonic missile.
Finally, it is important to stress that President Putin himself has cited the United States’ withdrawal from the Anti-Ballistic Missile Treaty in 2002 as the initial impetus for these new missile programmes. He has argued that developing these new weapons systems was necessary to preserve the balance of power, a point he has reiterated following the announcement of the US Golden Dome missile defence system.
Bibliography consulted
Lawrance Radiation Laboratory (1959), Tory II A A Nuclear Ramjet Test Reactor.
W. H. Esselman (1965), Westinghouse Engineer: The NERVA Nuclear Rocket Reactor Program, Vol. 25, No. 3.
Marquadrdt Corporation (1961), Annual Report for 1961 Nuclear Ramjet Propulsion System Project Pluto.
R. J. Weber, D. J. Connolley (1958), Preliminary Analysis of Nuclear-Powered Supersonic Airplane Using Ramjet Engines, NACA.
[1] https://nnss.gov/wp-content/uploads/2023/04/DOENV_763.pdf
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