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This is a brief compilation of a couple of different rumors I’ve heard out of the Ukraine war and what they mean. Now I don’t know much but I know a little bit about nukes and how they work and some of these things are flat out implausible. What I’m looking to give here is a quick reality check to see if any given statement is worth worrying about further. To be clear I’m talking about science; whether or not Putin is willing to deploy tactical nuclear weapons is beyond the scope of this post. Let’s get down to it.
Increasing Radiation levels at Chernobyl
The Claim: In the first day or two of the war the Russians attacked and took Chernobyl. The fight kicked up a lot of dust. The Ukrainian government’s automated radiation monitoring says the background radiation there jumped from 3,000 nSv/hour to 65,500 nSv/hour. Claim found in this video, though I’ve heard it elsewhere too.
Analysis: At first glance this is plausible. I’ve got no idea how their radiation detector is set up, but stirring up the dust of Chernobyl will almost certainly bring some more radioactive stuff to the surface. Increased evidence of the mess that’s there will read as increased radiation even if you’re not producing any more mess. I’m told that Ukraine monitors Chernobyl radiation and posts it online here. The page is blank in the English language version of the site. Perhaps the Ukrainian language version is more specific. If any of y’all speak Ukrainian or can find an English language mirror of the raw numbers I’d be interested in seeing them.
The next question is how big of a difference that radiation increase makes. Here we’re talking about the health and safety effects of radiation and I’m well out of my depth. I’ll throw a quick mention to the @OmegaPaladin who probably knows more.
A sievert (sV) is the SI unit for radiation exposure. For high dose exposures I get this line off of Wikipedia:
I read that as “If a Russian soldier stands around Chernobyl long enough to get one sV dose he’s 5.5% more likely to develop cancer over his life.” Not exactly the same thing as what they said, but close enough for our purposes. To get a 1 sV dose at the rates of 3,000 nSv/hour you’d have to stand there for… 38 years, or 22 months at the 65,500 nSv/hour figure.
To get any more complex than that you get into large and complicated questions of how exactly the radiation is delivered and what happens to someone at very low doses over a long period of time (an active argument in the medical community.) Taking a simplified chart from another source I’m told that 100 mSv is the lowest annual dose which has a statistically significant link to cancer. You’d get that in 61 days at the new, higher rate of radiation in the kicked-up dust of Chernobyl.
Bottom Line: I’d feel comfortable marching through the area but I wouldn’t want to garrison it for any length of time. This also depends a great deal on the numbers involved; I’d like more than two data points to make that determination.
Explosion Worries at the Zapro-whatsit Plant
The Claim: The Russians were firing on the Zaporizhzhia nuclear power plant. If it blows up it’ll be 10 times larger than Chernobyl. Taking the report from here and the specific claim from this tweet.
Analysis: There are two levels to this. The first is a claim that doesn’t get made but which you’re led to believe if you’re not careful, that if it blew up it’d blow up like an atom bomb. That simply can’t happen. The second level is that this attack could have resulted in a big, radiation spewing mess detectable on the other side of the globe. To deal with this let me give you a simplified overview of how atomic power works. I’ll try to be brief.
To get significant amounts of energy (read: explosions or electricity) out of atomic reactions you need to produce a chain reaction. A chain reaction is any reaction that happens where the reaction produces the conditions necessary to make more reactions. Think drunks in a bar fight; a missed swing inevitably hits an uninvolved drunk, converting him into an angry drunk. Now you’ve got one more bar fighter who can miss with his punches and spread the fight further. To get a nuclear chain reaction you split an atom by shooting a neutron at it. That split atom has to shoot off neutrons which can themselves split other atoms, and if you let that go on too long…
That only works with certain atoms, and not just individual elements but specific isotopes. Uranium 235 (92 protons, 143 neutrons) will work. Uranium 238 (92 protons, 136 neutrons) won’t. Take a bunch of pure uranium in its natural mix (about 99.3 % U238, 0.7% U235.) If you split a U235 atom in there then chances are the neutrons will hit U238 atoms. Those atoms won’t split and it’ll spoil your chain reaction. (There are some really fascinating things that happen but I’m trying to go quick here.)
To get a chain reaction you need a great deal more U235 percentage than nature allots. You need to enrich your Uranium. Without going into detail, you need to get it to at least 3% enrichment for a powerplant, and much higher than that for a nuclear bomb. (The NRC told me 20%, that link says 80%, the 80% seems more likely to me.) Either way, you need a lot more highly enriched uranium to get an atom bomb out than a power plant reaction. Why? Because you want your power plant to make a lot of heat (to boil water and turn turbines), but not do it so quickly that things blow up.
Okay, back to Ukraine and the war. Let’s say that the Russians indiscriminately bombed the reactor and by some magical chance all the uranium on the site got blasted into a perfect sphere. It still wouldn’t blow up. Though enriched there still isn’t enough U235 percentage to sustain the kind of reaction that leveled Hiroshima. That should put paid to the implied claim of a nuclear explosion. But if you did have that magical chance happen the mass of uranium would get really hot, there’d be no control rods to slow the reaction and you’d have a meltdown. Like Chernobyl.
Ten times worse though? Perhaps. Take the Chernobyl disaster and lob artillery strikes into it; you’d get material blasted into the atmosphere and probably a wider spread of radiation. On the other hand, I’ve had to imagine some pretty unlikely things to happen to get that far. Let’s take a step back and consider reactor design.
You know what you get from nuclear reactions? Radiation. You know what people don’t like to get? Radiation. As a rule, when you’re building a reactor you pour thick concrete walls between you and the radiation so as little of it hits you as you can get away with. The actual reactor core is better protected from bombardment than most bunkers. Even if the Russians came blundering in with a Homer Simpson-like casualness with where they’re landing their artillery strikes they’re unlikely to spread the nuclear pile around very much. Now, you can still do a great deal of damage. You can render the plant inoperable, you can probably make a local radiological spill, but you’re unlikely to make a disaster that’s ten times worse than Chernobyl.
From accounts everyone involved treated the situation with an appropriate gravity. The workers shut the plant down during the attack, the Russians didn’t direct strikes at the reactor building, and the building that caught fire was apparently a museum on the edge of the plant. The plant was subsequently surrendered without meltdown and the whole world can breathe a sigh of relief.
Bottom Line: The most fear-mongering claim of a nuclear explosion is impossible. The actual chances of a nuclear disaster on the scale of Chernobyl were minimal, and everyone involved with the fighting acted to avoid even that small chance.
The Ukrainian Dirty Bomb Program
The Claim: (taken from Meduza.io)
Russia’s news agencies promote allegations of a Ukrainian “dirty bomb” program: At roughly 8 a.m. [March 5th], Moscow time, Russia’s three main news agencies — RIA Novosti, Interfax, and TASS — all almost simultaneously reported, all citing what appears to be the same anonymous source, that Ukraine was allegedly developing nuclear weapons before Russia’s invasion. In their stories, RIA and Interfax published identical quotes from their source: “It’s worth noting that they were using the Chernobyl nuclear power plant zone as a site to develop nuclear weapons. It was there, judging by the available information, that they were working on manufacturing a ‘dirty bomb’ and plutonium separation. The Chernobyl zone’s increased background radiation concealed that this work was underway.” (Meduza was unable to verify these claims.)
Analysis: Start with a definition issue. “Dirty bomb” implies a specific type of weapon; you use a normal explosive and a jacket of highly radioactive stuff surrounding it. The explosive spreads the radioactive stuff over a wide area rendering it unusable for people. There’s no nuclear reaction involved; you’re just taking a compact problem and spreading it around.
Dirty bombs are difficult-but-plausible for terrorist groups to manufacture because it’s hard to acquire really radioactive stuff. For Ukraine — a government in possession of nuclear reactors — you have that stuff. The spent fuel from your reactors count. It’s so easy for Ukraine to turn a regular bomb into a dirty bomb that this isn’t the kind of threat you can dispel by invading. A Ukraine that was willing to make and use dirty bombs has plenty of time to do so in the face of invasion. They still can build one from one of their plants running in the still uncontested portions of Ukraine. It’s like asking if a baseball player has a weapon; sure — he was carrying a baseball bat.
According to the claim they’re doing more than making dirty bombs; they’re trying to build nuclear weapons of their own, meaning bombs that rely on a nuclear reaction as opposed to dirty bombs. To make a plutonium bomb you extract plutonium from your nuclear reactor’s spent fuel rods. From there need to shape it into a hollow sphere and implode it by means of carefully timed explosives. It’s harder than it sounds and it sounds plenty hard to me.
If you’re asking where the plutonium comes from it’s because you neglected to click my really fascinating stuff link in the previous section. If you hit U238 with a thermal neutron it’ll decay over a couple of days into Plutonium 239, which is the stuff that bombs are made of. But having the material is only the first step; Plutonium is difficult to extract and then to build a functioning bomb out of. To quote from the link:
Plutonium may be easier to get, but it’s harder to use. The weapon design is more demanding and, compared to a uranium gun bomb, without testing it’s difficult to be sure the bomb will go boom. While it used to be said that every country which had tried to build a nuclear weapon had succeeded on the first try, this is no longer the case: the North Korean 2006 nuclear test, believed to be a plutonium implosion device, appears to have had a fizzle yield of 0.48 kilotons. Basing one’s strategy on nuclear deterrence with plutonium weapons which have never been tested is risky in the extreme, although demonstrating the infrastructure may create sufficient ambiguity that adversaries are disinclined to roll the dice.
From a geopolitics perspective, it’s easy to imagine that pre-war Ukraine was feeling buyer’s remorse from the Budapest memorandum and looking to secretly develop its own nuclear weapons. They have the materials to do so on hand. The step from plutonium to Nagasaki, however, is a long one. They haven’t detonated any test bombs which probably means that they don’t have any nuclear bombs to test. On the other hand, a successful nuclear test not only shows the world that you have a program but also that you have the bombs which makes it much harder to shut down. Should such a program have existed I could imagine Putin having known of it and invaded to shut it down before it got far enough to threaten him. He should have had the decency to send Colin Powell to prove it to the UN first.
Bottom line: If Russia is worried about a Ukrainian dirty bomb that’s not the kind of threat they can defuse by invading. If they’re worried about a Ukrainian nuclear weapon program it’s at least plausible that such a program might exist. I’m waiting for them to submit proof before I believe it.
One More Note Before I Go
Remember I’m just some jerk on the internet. I don’t know much about these things, but I know enough to tell the difference between earplugs and rubber bullets. If I’ve missed any rumors you’d like checked out let me know. If I’ve made any glaring mistakes in my science (as opposed to the glaring oversimplifications) then let me know and I’ll correct them. And remember: rumors sprout like mushrooms in wartime. Don’t believe everything you read.Published in