Echos Of The Cold War: Nuclear-Powered Missiles Have Been Tried Before

On August 8th, an experimental nuclear device exploded at a military test facility in Nyonoksa, Russia. Thirty kilometers away, radiation levels in the city of Severodvinsk reportedly peaked at twenty times normal levels for the span of a few hours. Rumors began circulating about the severity of the event, and conflicting reports regarding forced evacuations of residents from nearby villages had some media outlets drawing comparisons with the Soviet Union’s handling of the Chernobyl disaster.

Today, there remain more questions than answers surrounding what happened at the Nyonoksa facility. It’s still unclear how many people were killed or injured in the explosion, or what the next steps are for the Russian government in terms of environmental cleanup at the coastal site. The exceptionally vague explanation given by state nuclear agency Rosatom saying that the explosion “occurred during the period of work related to the engineering and technical support of isotopic power sources in a liquid propulsion system”, has done little to assuage concerns.

The consensus of global intelligence agencies is that the test was likely part of Russia’s program to develop the 9M730 Burevestnik nuclear-powered cruise missile. Better known by its NATO designation SSC-X-9 Skyfall, the missile is said to offer virtually unlimited flight range and endurance. In theory the missile could remain airborne indefinitely, ready to divert to its intended target at a moment’s notice. An effectively unlimited range also means it could take whatever unpredictable or circuitous route necessary to best avoid the air defenses of the target nation. All while traveling at near-hypersonic speeds that make interception exceptionally difficult.

Such incredible claims might sound like saber rattling, or perhaps even something out of science fiction. But in reality, the basic technology for a nuclear-powered missile was developed and successfully tested nearly sixty years ago. Let’s take a look at this relic of the Cold War, and find out how Russia may be working to resolve some of the issues that lead to it being abandoned.

The Nuclear Ramjet

The obvious tactical advantages of an ultra-long range weapons delivery system led the United States to experiment with several nuclear propulsion systems in the decades after the Second World War. The goal of one of these programs, known as “Project Pluto”, was to develop an engine that would give an unmanned aircraft a range better than 100,000 miles (160,935 kilometers).

At the direction of Dr. Theodore Merkle, the Pluto project focused its research on the concept of a nuclear ramjet engine. On paper, it’s an ingeniously simple idea: run air through an unshielded nuclear reactor, and the resulting energy transfer causes the air to rapidly heat and expand. A nuclear ramjet requires no liquid fuel; as long as the reactor is producing sufficient heat, it will run indefinitely.

A nuclear ramjet still suffers from the same weakness of the traditional liquid-fueled version, namely the need to accelerate it up to around Mach 3 before the incoming air is compressed and pre-heated enough by the geometry of the intake for it to function. But with the addition of strap-on rocket boosters to get the vehicle up to speed, this wasn’t seen as a great engineering challenge at the dawn of the Space Age.

The larger problem was building a reactor core that was not only small and light enough to fit inside of the engine, but could also survive the intense heat required for the ramjet to function. The reactor would essentially be running in a continuous near-meltdown state, with only the flow of air to keep its internal structure cool enough to prevent it from tipping over the edge and spontaneously combusting.

Of course, this meant that slowing the aircraft down or stopping the engine was a dicey proposition. Once the engine was started, it was committed to just two possible outcomes: in peace it would crash (relatively harmlessly depending on how you look at it) into the ocean far from civilization, and if World War Three started, it would be plowed into an enemy target at full speed.

Unsafe at any Speed

Despite the obvious danger of developing and testing such an engine, Project Pluto actually produced two functional prototypes which were successfully run on the ground. The first engine, called Tory-IIA, was first fired on May 14th, 1961. It only ran for a few seconds, and was far too large to actually use for its intended purpose, but it proved the concept worked. Building on this success, a follow-up engine was constructed to flight-ready size and weight. That engine, Tory-IIC, ran for as long as five minutes during test runs in 1964. The nuclear ramjet was officially ready to fly.

But as it turns out, the project never progressed past that point. While plans were well underway for the engine’s eventual first host, the Supersonic Low Altitude Missile (SLAM), concerns over the cost and practicality of the technology compared to Intercontinental Ballistic Missiles (ICBMs) lead to its cancelation shortly after testing Tory-IIC. At least, that was the official reason for ending research into nuclear ramjets.

Critics of the program argued that such an engine would not only be a danger to the crews launching it, but anyone who was under its flight path. Radiation emanating from the unshielded reactor was bad enough, but the nuclear ramjet would also spew fission fragments out in its exhaust while in flight. Even if its patrol area was limited to high latitudes within the Arctic Circle, it would still be uncomfortably close to friendly countries like Greenland and Canada.

In 1958, while Tory-IIA was still under construction, Dr. Merkle was called by the Joint Committee on Atomic Energy to testify about the status of Project Pluto. In questioning, he acknowledged what he believed was a manageable radiation risk for the ground crews who would prepare the engine for flight, and confirmed that they had detected fission products in the engine’s exhaust. But he said that even by his team’s most pessimistic estimates, the speed and altitude at which a nuclear ramjet aircraft would operate meant that little radiation would actually reach the ground. He could not, however, guarantee safety should the vehicle crash.

Modern Evolution

With this context, we can see there’s a glaring issue with the theory that Russia was testing a nuclear ramjet at Nyonoksa. The Rosatom statement specifically mentions “liquid propulsion”, which is at odds with what we know about the research conducted during Project Pluto. More to the point, there’s no way an engine that consumed a liquid propellant could deliver on the promised range and endurance goals of a nuclear engine. So what exactly were they working on?

Ignoring for the moment the possibility that the official statement was intentionally misleading or potentially mistranslated, the mention of liquid propulsion could be a hint that Russian engineers are attempting to address the most critical problems of the classical nuclear ramjet with the addition of liquid cooling. In this scenario, rather than the reactor being physically located inside of the engine itself, it’s connected via a closed-loop heat exchanger filled with a substance that will remain liquid even at extreme temperatures such as molten salt or metal.

Diagram of an Indirect Air Cycle turbojet

The United States experimented with this idea, known as the “Indirect Air Cycle”, during the Aircraft Nuclear Propulsion (ANP) program. Run from 1946 up until 1961, the ANP was eventually canceled by President Kennedy for ostensibly the same reasons Project Pluto was shelved: immense cost and complexity when compared to ICBMs. While the program never produced a practical aircraft engine, it did lead to the creation of the world’s first operational molten salt reactor (MSR).

Outfitting a nuclear ramjet with a molten salt or metal cooling system would allow heat to be transferred to the engine from a shielded reactor. This would not only make the system safer for the crews handling and launching it, but would remove the risk of fission products being released in the exhaust as air would not travel through the core itself.

In theory, it could also allow for deeper throttle capability and a safe shutdown procedure, assuming the liquid coolant could be redirected to external radiators to help control core temperature at lower airspeeds. Of course, the downside is that such an engine would be vastly more complex. But it also may mean the difference between a historical curiosity and a viable propulsion system.

Theories and Speculation

When he acknowledged its existence last year, Russian President Vladimir Putin said that development of the Skyfall missile was already far enough along that some early test flights had been completed. With rumors that the weapon could become fully operational by the mid-2020s to coincide with the deployment of the Avangard hypersonic glide vehicle, it would seem a reasonable assumption that its propulsion system would be undergoing active testing. But in reality, nobody outside the Kremlin truly knows what happened at the Nyonoksa facility on August 8th; and if history is any indication, we may never get the whole story.

It’s possible they were testing some evolved version of the nuclear ramjet, but it’s also possible the blast involved Poseidon, the nuclear-powered torpedo that Russia has been developing since 2015. Some have even theorized that the incident involved a next-generation radioisotope thermoelectric generator (RTG), a small nuclear power source designed for deep space probes and rovers.

For now, all we know is that engineers have lost their lives, citizens are at risk of being driven from their homes due to radioactive material being released, and the Russian government is not being forthcoming with information about what’s really happened. Even if the technology itself is cutting edge, its development certainly exhibits all the worst hallmarks of Cold War era politics.

63 thoughts on “Echos Of The Cold War: Nuclear-Powered Missiles Have Been Tried Before

      1. What would you have them do? Other than condemning the development of more nuclear weapons (which, let’s be honest, is a pretty hollow gesture), what else would be an appropriate response?

        It’s nobody’s problem but the Russians if they want to fiddle around with nuclear tech and risk there own people. No foreign country can make them stop.

          1. I Agree, not warning other countries of airborne hazards that they have created and that will linger for years (if not centuries) is the height of hubris. If a nation could be compared to an individual then I would say they should be committed since they are a danger to themselves or others.

        1. You act like the Russian government effectively owns all their citizenry and can do with them whatever they please, like livestock. You also forget that this test site is right next to Finland and Norway. If a meltdown happened, it wouldn’t be contained to one country. Chernobyl wasn’t, either. If they didn’t suicidally work to contain that thing it would have contaminated much of Europe. They were weeks away from it being a global problem.

          Not that there’s anything that could really be done to stop them if they really want to keep going forward with development. I mean what are we gonna do—invade Russia? We know that’s a bad idea from plenty of history.

          Nuclear propulsion is a great idea: for orbit-to-orbit use in space. It’s probably the only way we’re going to build any space infrastructure and a lasting human presence. But in atmosphere? It’s insane. These aren’t reactors in the same sense as a relatively safe ground-based nuclear power plant. Mistake number one. They’re waaayyy lighter on shielding and run far, far hotter. Even the design with a liquid heat exchanger so the reactor doesn’t literally spew fission products into the open air is very dangerous for atmospheric use. If this were a ground-based reactor, we’d basically say it was in meltdown for the entire duration of what is considered its normal operating condition. It really straddles that edge in order to strike a balance between small and light enough and powerful enough to heat sufficient propellant and do its job. It stays just a hair below the threshold of the temperature at which everything becomes white-hot irradiated liquid. This is Reaver shit, if any of y’all are Firefly fans. For real.

          Not to mention that any mistake or glitch would send it plummeting to the ground to crack open its already very thin containment, catapulting its ravenously-fissioning core in a plume that would spread with its own prodigious heat up into the atmosphere and out to the ends of the whole dang Earth. Also a way it’s very different from a ground-based reactor; virtually any meltdown would resist attempts at containment and immediately spread much wider than a Chernobyl-style event. There would be no waiting for it to melt through the thick concrete foundation and sink into the groundwater. It would immediately be a diffuse cloud across hundreds of square kilometers. All the safety mechanisms we expect in a modern nuclear reactor are very heavy and would have no room here. Not that they would help if you augered into the permafrost at Mach 3, anyway.

          1. > You act like the Russian government effectively owns all their citizenry and can do with them whatever they please, like livestock.

            Russian government very much acts like this.

            > I mean what are we gonna do—invade Russia? We know that’s a bad idea from plenty of history.

            Hmm, push Poland to angry Russia enough, so that Russia attacks Poland. USA recently stated that at last they will remove visa requirements to poles. It’s seen as THE political gesture and fulfillment of 30 years of polish dreams.

          2. @yetihehe

            USA protect Poland? haha

            You mean in the same way they protected Ukraine?
            When you consider the USA and various others signed a treaty to do so in exchange for Ukraine giving up their nukes.

            USA doesnt run the world any more. Action against China is too little too late.

          3. Pushing Poland to do something stupid so that your hands are clean is not exactly protecting. “THE political statement” is used here as a pun, because it’s just convenient for USA. They don’t want to be seen as bullies, so they use other countries as pretexts. I don’t think anyone will really protect Poland.

          4. @ yetihehe
            “USA recently stated that at last they will remove visa requirements to poles.”
            Similar promises has been given by Bush and Obama already. But finally they explained that it’s not what they meant. Bush even said it’s a congress matter not president.

            “It’s seen as THE political gesture”
            No, it is seen as long awaited gesture (no “the”, no capital letters) for 30 years of cooperation.

            “and fulfillment of 30 years of polish dreams.”
            That is not Polish dream for a long time. Meanwhile new opportunities appeared, more available and similarly attractive so Poland kind of woke up.

            “push Poland to angry Russia enough, so that Russia attacks Poland.”
            Than finance that war but not take part in (maybe if war escalates and western europe needs help). No territory to loose, US citizens separated with ocean from that war. So… visa requirement will stay I guess.

      2. Oh, I’m pretty sure that the US government isn’t doing absolutely nothing. I’m sure there’s some general, in some broom-closet in the Pentagon, who is dusting off plans for Project Pluto and the SLAM, so that we can build our own version. :-( Remember, bad ideas never really ever go away.

        1. In December of 1980, there was a much documented UFO sighting in Texas that absolutely fits the scenarios mentioned here. Please read the Cash-Landrum Incident (I will place a link to the Wikipedia version however more detailed versions of the story are around). I am not the brightest person on the earth, but it certainly sounds like this was a full test of just such a vehicle. The only thing that is strange is that this was during the Carter administration and not the Reagan presidency. However it fits the buildup that the US was doing during that time. Let me know if you think I am on to something. It would be nice to actually solve one of these unsolved mysteries.
          https://en.wikipedia.org/wiki/Cash-Landrum_incident

      3. In this chess game, I’m unsure of what move the US has, it could make.. No matter how missile powered by the tech is, it isn’t fast enough to stop a retaliatory defense response.

  1. I knew a man when I was younger that worked at Sandia in the 1950’s. The project he worked on was to build a nuclear missile that did not explode, just fly around a city and dump radiation. This would effectively leave the infrastructure but eliminate all life in the area.

    The cold war era sure was brutal.

    1. That’s Pluto. This article depicts it as if it were basically an early alternative to an ICBM; primarily a warhead-delivery device. Nope. The warhead was practically an afterthought on this thing. A final little horror after an incredible nightmare that honestly a nuke pales in comparison to. The primary function of the design, like you say, would be to basically do laps around a target country at several times the speed of sound—puking radiation everywhere—until it ran out of fissionable nuclear fuel, at which point it would have done the equivalent of several circumnavigations of the globe and the whole target country would be basically be glowing Cherenkov blue. This thing was real nasty, an absolute condemnation of the Cold War attitudes. Just a big hypersonic war crime.

      1. Pluto was the project to develop an engine, what you’re thinking of is SLAM, which is what the engine would have eventually been installed in.

        But your description of it is the product of a very common misconception. If you read the linked 1958 testimony, the radiation that would actually reach the ground was minimal. The idea that it would just fly around irradiating people has no basis in fact.

        1. Sure, SLAM was designed to fly at tree top levels at supersonic speeds spewing radiation.

          Pure evil.

          Generally I take the scientitists testimony with a large bucket of salt. After all these were the same monsters that detonated nuclear warheads in Nevada and then marched soldiers into the blast and fall out. They also irradiated civilians in hospitals without their consent. Even giving lethal X-Ray doses to people with terminal cancers.

          They were very bad men with no conscience.

          1. You have to remember that the air is moving through the reactor at MACH 3 (~1800mph), so there is very little time for it to be irradiated. Equally, the direct radiation from the reactor isn’t much of problem when it’s gone past you at 1800mph (there’s obviously much more serious problems from an aircraft passing you at MACH3 at close range).
            Effectively you’d be getting the equivalent of multiple chest x-rays at one time. A lot certainly, but still less than a standard annual dose.
            The main radiation hazard would be fission fragments, or indeed literal fragments of the reactor, coming out of the back.
            Of course, the REAL main radiation danger from a SLAM would be the nuclear bombs it was designed to drop as it flew around, those would be what would really ruin your day.

      2. There actually would not be much fallout from the exhaust unless the core started breaking down and releasing fragments of fission material.
        The sonic boom it would make from flying by would be more destructive.
        But the missile will still make a big mess where ever it comes down especially if it had been cruising around for a couple of weeks on standby as the core material will be very hot radiologically speaking.
        SLAM was actually was more of what we’d call a UCAV than a traditional cruise missile as it was to drop multiple bombs on it’s mission.

    2. *ahem*

      https://en.wikipedia.org/wiki/Neutron_bomb

      It was designed to produce as much radiation as possible while limiting the “thermo” part of a “thermonuclear bomb” (and yes, I know a “thermonuclear bomb” is a fusion, not fission, bomb. But both make things very, VERY hot very, VERY fast. The neutron bomb was intended to be lots of radiation and less physically damaging. Also they were trying to limit the radioisotopes that would contaminate what infrastructure that wasn’t melted or blown to dust.)

      1. Because every single time you test a device that needs to get up to speed before it can function in nuclear ramjet mode, should be carrying a full nuclear payload instead of cheap ballast weight ?

        That would make total sense. /s

        1. What I mean(t) is/was…
          A nuclear explosion (the size of meteorite blast) at the altitude it occurred, would have placed enough radioactive fallout into the jet stream/upper atmosphere to have triggered radiation monitors throughout the Northern Hemisphere.

          And fingers would begin pointing at Russia (because of the publicity surrounding the blast) if the monitors triggered.
          Come to think of it, if it had been a nuclear accident, don’t you think Russia would have silenced any attempt to put the dash cam videos on social media?

    1. I would say that the dash cam footage showing it FALLING FROM THE SKY in some way confirms that it was a meteorite. Missiles usually operate at speeds that don’t cause them to burn up in the atmosphere.

  2. “It’s also possible the blast involved Poseidon, the nuclear-powered torpedo that Russia has been developing since 2015.” The whole idea of a nuclear torpedo is a bit weird. It seems to fit in with some of the Cold War weapons like the Davy Crockett – something based around the idea that using small nukes wouldn’t tempt the other side to respond with bigger nukes. And, like the Davy Crockett, it seems like such a weapon would be almost as dangerous to the people firing it as it would be to their targets. The nuclear cruise missile at least falls into the usual “threaten complete worldwide destruction” scenario.

    1. The idea behind Poseidon appears to be that a nuclear torpedo can creep along at a couple of knots halfway around the world and be almost undetectable along the route because it’s so quiet, right up until it detonates in Boston Harbor or under a carrier group.

    2. Not sure about Poseidon but during the cold war the Soviets had nuclear tipped torpedoes, I heard that the sub crews knew that it was a suicide weapon and would only have used them as a last resort to stop an
      imminent nuclear strike or sink a large carrier fleet in the case of the war going hot. They knew that NATO subs were quieter and would get the drop on them so if they were going to get taken out they would do their best to take the NATO sub with them.

      My source on this is the streamer Jive Turkey, he is an ex sonar operator for the US Navy, his streams are filled with all sorts of interesting info about sub and sub life.

  3. from the descriptions, it sounds more like they’re trying to use some sort of working fluid and using the reactor to heat it to expansion. getting an explosion instead of a meltdown to me, suggests more of the same. something got too hot or ran away and “vented” in an extraordinarily energetic manner. Steam explosions are spectacular, and if this was a dense working fluid, the kinetic energy of the steam itself wouldnt dissipate quite as fast either. the upshot of this, would theoretically be incredible impulse but still limited on range.

  4. Putin himself said that the accident was related to weapon system development yesterday while visiting Finland. Not much to derive from that except that we can most probably rule out the space exploration option.

    1. Strange thing happened in Moscow just after accident. Local tv stopped all the programmes and put only message to screen that ” hard storm coming to town, keep inside and close windows” !!! Nothing about any radiation warning !

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