Update September 2: If one believes CNBC’s story here then the cause of the incident was a failed recovery attempt of a prior Burevestnik missile test from 2018. In recovering the missile from the bottom of the bay something exploded under one of the vessels, which also damaged the missile’s reactor, leading to the radiation release. So there was no missile test, no reactor test, no launch, and equally there was no RTG or some other device responsible. I will leave the rest of the text below without updates so you can see my thought process, right or wrong, early on in this episode before much information was available.

I was going to stay away from this because there simply was not enough information to tell what happened, and the hot take factory had already run away with the story on the basis of close to nothing. Here is the most likely scenario as I see it. The explosion was not a missile launch test, and it was not Burevestnik, no matter how much arms control wonks want to think it was. It’s just unlikely based on the scant information available about the incident.

I have a different view from Jeffrey Lewis here. The notion that Russian Burevestnik program was in major trouble after moving from Novaya Zemlya test site is also probably incorrect. I think Lewis’ own commercial satellite imagery confirms the story that VNIIEF, the Russian nuclear research institute in charge of this work, basically tried to tell but couldn’t get out in time because people already piled in with speculation.

They were testing the system on a platform at sea. According to some accounts the explosion blew the scientists into the water, which is why it took time for an accurate casualty count to come in as they were looking for their own people. It was not a missile launch, as such launches are easily detected by national technical means, and it was not on a rail launcher since we can clearly see one affixed on land at the test site. Why would they rail launch it from a platform at sea when they can fire it over the bay from the coast?

Update August 26: Looks like its not a RTG based on the isotopes detected, and instead a nuclear reactor. Also unlikely to have been a missile, and the initial explosion may have taken place underneath the platform rather than above it.

Let’s ask first order questions. Why did five leading researchers die? If it was a nuclear powered missile test why would they be near the missile? I know I’m always standing next to experimental missiles I’m testing, it’s the best way to see the explosion. If it was an experimental nuclear reactor (unshielded), why were they standing next to it at the time of the mishap? I know I always stand next to experimental nuclear reactors I’m testing. Typically when people stand around things, it is because they don’t expect them to explode or massively irradiate them.

The explosion was caused by a liquid fueled engine – why would there be a liquid fuel engine in Burevestnik? Subsonic cruise missiles have solid fuel as their boost phase. Ok here is the last question for Burevestnik theory enthusiasts. Imagine they are conducting a missile test on a small platform out at sea, and you believe that this is a missile powered by an unshielded reactor. I mean, kind of hard to shield a reactor on a relatively small cruise missile. In this theory Russia’s leading nuclear researchers are standing around an unshielded nuclear reactor on a barge, with the intent to turn it on. Forgive my skepticism.

I know you’re thinking, well maybe they lied about the platform and were testing it at the rail launcher site. So why were the scientists next to it then, and another question, why are there all these ships positioned in the flight path of the missile from the rail launcher? Wouldn’t the radiation from the reactor be a problem for them, the entire bay, maybe the towns?

Some in Russia have combined the two theories, suggesting that Burevestnik has a nuclear power component, but there is a separate liquid fueled engine for maneuverability. While interesting, its still unclear how either system actually powers Burevestnik and why a subsonic missile with maneuvering surfaces would remotely need liquid fueled thrusters or jets to maneuver. I’m raising this here to dismiss it because it doesn’t make much technical sense. We will get back to Burevestnik later.

VNIIEF’s statement, in classic Russian style, alluded to two types of projects without saying exactly what it was, a novel Radioisotope Thermoelectric Generator or a novel reactor type akin to U.S. Kilopower project. In my view they were indeed testing a novel Radioisotope Thermoelectric Generator with a liquid fuel engine combo. (That turned out untrue after it became clear that the different nuclides produced could only come from nuclear fission).

The idea being to use the RTG as a long term electrical heating solution to maintain thermostatic temperature inside the various components of a liquid fueled engine, either in a booster phase, or the canister itself, of a missile that needs to get up to speed very quickly from launch. Basically an atomic battery for a liquid fueled engine where the components have to be kept at a certain temperature in prolonged storage, otherwise the weapon has to be permanently connected to a power source. This is certainly not as sexy as a nuclear powered missile, but it’s much more probable as the real story behind what happened. That’s the story IZ eventually went with and (I believed it was closer to the truth than all the Burevestnik mania, but it turned out not to be a RTG)

Some of my musings on alternate explanations:

If we ask which secretive missile the Russian military is working on, that is principally for the Russian Navy, has most likely a high power liquid fuel engine – it’s could well be Tsirkon. Since Tsirkon has to be canister stored, and quickly sprint to a high velocity for its scramjet to work, most likely this missile could benefit from a RTG. It could be part of the canister storage system, or fall off as a booster. Some have also suggested Skif, a SLBM designed to be fired from the ocean seabed, even though that would violate a treaty banning such weapons. If its a liquid powered engine, then I’m skeptical on Skif and leaning towards Tsirkon, because the latter is likely to have a powerful liquid fueled engine/scramjet combo, and is actively being worked on whereas I’ve really not seen evidence of Skif being a thing. (it was none of these things either)

While we’re in the speculation business on RTG use, it might also be a maneuvering satellite. That sort of weapon could use a sustained power source, in space, and possibly have liquid fueled thrusters. Just working through the non-Burevestnik list here. If the radiation emitted sounds too high for a RTG, and I’m not an expert here so I don’t know how much radiation you get if you blow one up, I suppose it varies considerably depending on the type of material used and how much of it they were using. RTGs are fairly simple in design, but perhaps this RTG was novel and therefore more powerful.

Equally likely it was a novel nuclear power source, but again it begs the question as to the cause of an explosion, and why leading researchers would ever be standing around such a thing on a platform at sea. The obvious answer is they were setting up equipment, but I don’t see them testing an unshielded reactor off the coast of a town near Severodvinsk.

Now let’s imagine that the RTG story is a canard meant to distract us (which it turned out to be in retrospect). It could be a novel nuclear power source, but for what? Well, probably 10-20 different projects, at least those that I can think of. I’m not ruling out a component related to Burevestnik, but saying that something was tested with infrastructure associated with Burevestnik tests is like going to Kaputsin Yar and just guessing which missile was involved at a range testing 10 different missiles.

The scientists, the explosion and a source of radiation were all co-located which suggests they were working on something with explosive potential and a source of radiation. The radiation released seems quite small for a reactor, just my impression based on commentary from people who follow the nuclear side of things but perhaps too high for a typical RTG. So the circumstances suggest it was something other than an unshielded reactor, involving an engine with liquid fuel propulsion, which should point us away from Burevestnik.

Moscow Times released a story from the hospital talking about exposure to Cesium 137 isotope, which while a byproduct of fission, is a source of gamma radiation. The thing is Cs-137 is total junk for power level and is basically one of the weakest isotope sources you can use for a RTG. Good PDF here with comparisons for those interested.

So after initially leaning towards the RTG story, it seems that was a distraction and instead we are dealing with a nuclear reactor. There are several options for nuclear reactor tests with military applications at sea, from Poseidon torpedo to various types of ATGU’s, undersea atomic power stations, to of course our reactor for Burevestnik. However, to release these different isotopes it is likely that fission might have had to take place at the site, whereas in a missile the reactor would not turn on until after boost phase, which creates obvious problems since the explosion and material was released from the platform.

Back to Burevestnik

I wonder why people assume that Burevestnik is an open air flow reactor/ramject powered missile? Just because in 1960s U.S. project Pluto used this combination on a large supersonic missile does it make sense to assume that’s what Russia is working on as well? The U.S. tried to build 1957-1964, and it doesn’t make much sense that it is what Russia would try to build in 2019. Pluto was a large supersonic missile, with rocket boosters and multiple warheads designed as a supersonic low altitude missile (SLAM), while Burevestnik is a single warhead cruise missile shaped for subsonic or perhaps transonic flight. Its certainly not a mach 2 weapon.

Burevestnik clearly doesn’t look like a supersonic low altitude missile with those wing surfaces.

Given Burevestnik appears to be a subsonic, or a transonic missile, not meant for supersonic flight and therefore not utilizing a ramjet which is better suited for mach 2+ it is probably not an open air flow system. Ramjets are highly inefficient at slower speeds and the wings on the missile don’t exactly look like a mach 2+ weapon. Burevestnik is going to have probably one of two propulsion types, direct air cycle or indirect air cycle. Direct air cycle just throws the air into the reactor and out the back. Highly radioactive. Indirect cycle is probably liquid metal cooled. Air makes contact with a heat exchanger that’s carrying the liquid metal from the reactor and goes out the back, much less radioactive. Of course maybe there is a nuclear power source just powering a turbojet and they’re not using the air for propulsion at all.

Also I don’t think its index is 9M730, although it was initially reported as such. There are still too many assumptions here about an experimental weapon without enough images or information, so in my view it is best to hold back on the guesswork.

Comments and feedback as always welcome. If you have alternative explanations please send them in. I do not know what it was, but there’s enough information to suggest that the hot take factory is wrong on this one.