As someone who has studied nuclear war for close to forty years now, I am going to give you an answer that will blow your mind. Even if the entire Russian nuclear arsenal were used against Ukraine, it wouldn't substantially change the course of the war. How could I possibly say that? Because, the power of nuclear weapons has been used as a boogeyman for so long that the actual power of a nuclear detonation has almost no relation to their actual destructive power. No nuclear power can afford to actually use one in combat because it would expose the mythical nature of nuclear weapons.

Nuclear weapons are hyped to the point that no one contradicts it when a media outlet publishes a statement indicating that even a single nuclear device will destroy the world. This is a blatantly, stupidly, obviously untrue, but never corrected. After all, two were used in WWII. BUT that is just the tip of the iceburg. I thought there had been a couple of hundred nuclear test that prove this point. I was off by over an order of magnitude. There have been nearly THREE THOUSAND NUCLEAR DETONATIONS ALREADY, that are either known or suspected and this has not effected the survivability of life on Earth even slightly.

Well then, how dangerous are nuclear weapons? Nuclear weapons, if they weren't their own catagory, would be classified as incendiary weapons. They set stuff on fire. They set a lot of stuff on fire. In fact they can set things on fire as far as two miles away from the actual detonation. Besides this, nuclear detonation are very bright, capable of blinding people 20–30 miles away. This is only constrained by the curvature of the earth. They also create hurricane force winds as the air around the detonation expands and contracts. If you are outside and unshielded and within a mile of a nuclear detonation, you are going to die!

The problem here is that Ukraine is really big. I mean bigger than the state of Texas big. Cities there tend to be spread out in modern times and their larger ones cover over a hundred square miles. The average nuclear detonation are only burn 2–3 square miles of territory. A city the size of Kiev would take on the order of 200 warheads to cover the whole thing.

Which brings us to our next point. Modern cities are just not that vulnerable to incendiaries. Modern city centers and industrial areas are made of concrete and steel. Most of the damage in Hiroshima and Nagasaki was done because almost all the buildings were made of wood and paper. The initial blast set the city centers on fire which spread and ended up burning down most of the city. Modern cities are just not that vulnerable. In Ukraine, despite millions of rounds of being poured into their cities, not one of them caught fire and burned to the ground like the Great Chicago Fire in the 19th century or the fire storms of WWII. In the Japanese nuclear detonations, the brick buildings were still standing, despite being much less sturdy than modern buildings.

This leads to the most surprising revelation about nuclear detonations: If you are not outside, you stand a good chance of surviving even within the blast zone. Nuclear blasts are mainly line of sight killers. The vast majority of “radiation” created by an nuclear detonation is infrared radiation, or heat the same as a gas stove or fireplace makes. Unless the building you are in is collapsed by the wind or you fail to leave if it catches on fire or you happen to be in front of a window with a direct line of sight to the detonation, there is a good chance that you are going to be fine.

Thus we get to the real reason why Putin will not use nuclear weapons: they're just not all that effective compared to the boogeyman that is in our collective imaginations. Were a nuclear missile to detonate over central Kiev, no one would believe that it was an actual nuclear blast because the city is still there and all the major buildings are still standing.

Secondly, he doesn't have very many of them. The numbers given for the Russian nuclear arsenal are an outright farce. You get that number by taking of bombs that the USSR claimed to have built, and subtract the number used in their testing program. This leaves you with about 9,000 warheads. First of all, Russia doesn't have nearly enough delivery systems to put those warheads on. The second problem here is that nuclear warheads have a very short shelf life. Nuclear warheads require a detonator made of conventional expolsives and a mechanical trigger. These nuclear triggers are some of the most precision pieces of engineering in the history of mankind. A series of explosives has to go off in such a way that the core is hit by the same amount of pressure from all directions simultaneously. If any of those explosives are even slightly off, the nuclear warhead will not go off. You now have an extremely precise machine sitting around a core of material emiting hard radiation. Hard radiation is not friendly to machines. Nuclear warheads need to be rebuilt a least every five years and maintained a lot more often than that. Even with that, a twenty year old warhead is a piece of junk. It's been more than twenty years since the Putin kleptocracy came to power and sold off all the factories that made the components in their warheads. I'm sure that Russia has a number of Potemkin warheads that are kept in top shape for inspectors, but given the current Russian system, the Russian nuclear arsenal most likely resembles the Russian tank reserves: the bare minimum kept in service while the rest is a scrap pile.

This number for the discussion of the Russian-Ukraine war is even smaller as large nuclear warheads cannot be used in this conflict. Large nuclear warheads can only be delivered by ICBMs and gravity bombs. Gravity bombs are right out as Russian bombers cannot get within hundreds of miles of the frontlines without being shot down. ICBMs cannot be used as any trajectory that would hit Ukraine would also be the same trajectory that could hit a NATO country and would be considered an act of war that would trigger a retaliatory strike even before it reached its target and could still be shot down by Ukrainian defenses. The only forn of nuclear warhead that would have a chance of being used successfully are tactical warheads placed on cruise missiles and even these have a low chance of getting through as cruise missiles with conventional warheads are being regularly shot down by Ukrainian defenses.

Currently, the spector of the vast Russian nuclear arsenal is the last card he has in his hand. If he were to actually use it, it would expose that he never had anything but a junk hand and bluffing to back it up.

Update 9/16/2022:

The response to his post here been overwhelming and I very much appreciate those of you who have asked a number of sincere and insightful questions. I am going to try and clarify and expand here as the reply thread has gotten quite long. Nuclear weapons are the most deadly weapons that mankind has ever made, capable of killing tens of thousands of people at a time. It would be insane not to fear and respect that kind of power. On the other hand, even the most powerful nuclear warhead is not capable of killing millions, destroying our civilization, causing the extinction of mankind, or destroying the planet. There is a middle ground between being completely ineffective the apocalypse.

Some clarifications about the types of nuclear explosions and categories of warheads.

There are five categories of nuclear device: Air burst, bunker buster, laydown, torpedo, and mine. Mines and torpedoes are not relevant to our discussion here. Air burst bombs are the classical nuclear bomb with the mushroom cloud. These are detonated at altitude in order to do as much damage over as wide an area as possible. Bunker buster bombs are designed to destroy underground installations like bunkers. Lay down bombs are the predecessors of the bunker busters and have mostly been phased out although a few US warheads still retain the capacity to be converted to this configuration. The Russians, who knows.

Getting through heavily fortified and buried installations like bunkers and missile silos is basically impossible for airbursts. Making a bunker buster nuke is a very difficult task from an engineering perspective. Since atomic fuses are relatively fragile, putting a shell around an atomic warhead that will keep it intact through the impact of hitting the ground takes a lot of very precise work. An easier idea was used. To incapacitate silos and bunkers, simply drop a nuclear warhead with a parachute right next to the entrance and then bury it in debris or melt it shut inside the nuclear fireball. This was a messy, dirty and insanely expensive option requiring the largest warheads to be used in a very ineffective way. When workable bunker buster nukes were produced, the largest warheads were retired as a bunker buster could go a better job with a smaller warhead with less collateral damage. In the context of our discussion, the use of a lay down warhead is a near impossibility. It requires a bomber to get physically over its target which the Russians have been unable to do for the entire war. It also requires the bomb to remain intact as it is parachuting down, which is even more unlikely as it would be a sitting duck for air defences.

There are four kinds of nuclear explosions that are talked about:

Neutron bombs are nuclear detonations that produce large amounts of hard radiation at the cost of producing very little physical damage. These were micro nukes with warheads as small as 20 tons who were either to be used as anti personnel weapons or as anti ballistic missile weapons. These were banned by mutual treaty in the 1970s with the ABM treaty except for a single defense site in the US and the USSR. The US dropped their program because they their job could be done more effectively by conventional systems at a much lower cost. Because of this Neutron bombs do not currently exist as far as anyone can tell.

Third stage bombs are in a similar position without the treaty ban. In theory, a third stage bomb uses a four stage detonation to set off an explosion in the multi-megaton range. Any stats on their power are made up as everything to do with them is massively classified. The infamous Tsar Bomba was an attempt to make a third stage bomb and this prototype is acknowledged to have caused the most powerful nuclear detonation in history … and then the program was dropped. (The US had a program that was similar in nature, but not as powerful result and was similarly dropped.) Again, no third stage bombs actally exist. (1)

This leaves us with fission and fusion bombs. These bombs actually exist and have been tested extensively. Unfortunately for the purposes of our discussion, the tests are highly classified. The only data available to the public is from the Hiroshima and Nagasaki bombs and is over 75 years out of date. In the intervening time, Uranium based warheads have been replaced with Plutonium based warheads almost completely. Thus makes comparisons very difficult. How do we know anything about modern nuclear warheads? Well, they still obey the laws of physics. (2)

Fission warheads work by a two stage explosion. A set of conventional explosives form a shell around a core of highly enriched Uranium or Plutonium. This explosion has to be mind bogglingly precise or you only pulverized the core (creating an unintentional dirty bomb). The level of precision required is that if you had a steel ping pong ball in the middle that after the explosion the ping pong ball would be perfectly intact. This level of precision is unmatched in any other device made by humanity, except fusion warheads. (3)

Fusion warheads have a three stage explosion in which a conventional explosive shell sets off a fission explosive shell to trigger a fusion explosion. This is orders of magnitude more complex than a fission warhead.

This brings to the most common set of questions: Just what are the effects of a nuclear detonation? A nuclear explosion converts some of radioactive core into pure energy and hard radiation. Simple enough, but the devil is in the details. The equivalent of a small piece of the sun being brought into existence in the atmosphere for a fraction of a second (this is the nuclear fireball which has temperatures similar to the sun(4). This sends out radiation across the spectrum from Gamma rays to radio waves (including EMPs) but not in equal amounts. Most of the radiation is Thermal or visible; AKA heat and light. This radiation goes out in straight lines (line of sight) for a fraction of a second. This is relevant because this radiation is only there for a fraction of a second and then is gone leaving only its effects. A small amount of alpha and beta particles (hard radiation) are also produced. This radiation is also absorbed by the first solid object it runs into. The amount of energy transferred depends of the distance from the explosion by the inverse cube law. This damages things by cooking flesh and settings things on fire. The range at which people are killed and things are set on fire is known as the damage radius. If you are in the damage radius and you have a direct line of sight you will be burned to death. This is also the range that you might receive a fatal dose of radiation, but as you are already dead from the heat, it doesn't really matter. EMPs are also generated in this zone, which means that any computer chips or diodes within the zone will be fried even if they survive the heat. That's it for the direct effect of a nuclear detonation. Secondary effects will be covered later.(5)

The thing is that radiation follows the inverse cube law, which means that the effects drop off very quickly.(6) Nuclear bombs are rated in explosive force equivalent to a number of tons of TNT. This gives a rough estimate of their damage radius. The bigger the number, the bigger the damage raduis is roughly. (The Hiroshima bomb was rated at 15 KT and killed about 50% more people than the 20 KT Nagasaki bomb so we already know its not an absolute ratio.) Just outside of the damage radius, there is a small edge zone. People in a direct line of sight of this explosion within the edge zone will receive serious burns that are not immediately fatal as well as high doses of other forms of radiation besides visible and thermal. These are the people who are the most likely to survive the blast but later die of burns or radiation sickness. This edge zone is only a few hundred feet across and being on the side of the street closer to the blast can literally mean the difference between life and death.(7)

Time for mind blowing revelation number three. Hard radiation is crated by a nuclear warhead in several ways and this can and is deadly, but the way they present it in the media is opposite of how dangerous it is. Radioactive isotopes have well known half lives, but unlike what you have been told all of your lives, the longer the half life, the less dangerous it is. Uranium is not dangerous until it decays. But since Uranium has a half life measured in billions of years, this means that it doesn't release alpha particles hardly at all. The alpha particles are helium nuclei, which is where we get commercial helium from. In fact any radioactive isotope with a half life of over 100,000 years is not a radiation hazard at all. Its the short lived isotopes that are deadly. Many of the isotopes that are secondary effects of a nuclear explosion are very dangerous … for a few days, and then they are used up and gone. There is a “sweet spot” of dangerous isotopes that last long enough to produce significant amount of radiation, but even that is not the end of the story. Different isotopes release different kinds of radiation. The most common kind of radiation released infrared radiation or heat. This is why radioactive materials are referred to as hot, because it can be literally true. To give you another example, carbon14 is a radioactive isotope with a half life of 5000 years. Carbon14 is in EVERY LIVING THING, and everything that has ever lived, yet we are still all alive.

To use a counter example. Cobalt bombs significantly increases the death rate from hard radiation by adding a few ounces to a few pounds of cobalt to the core material of a nuclear warhead. A few pounds … vaporized and spread over several square miles. This means that the normal hard radiation danger is so small that a few parts per billion of a dangerous isotope could cause a major increase in the death rate.

This was proven by the Chernobyl disaster. The explosion at the Chernobyl nuclear was the largest airborne release of enriched radioactive material in history. Spikes in radioactivity were recorder all over the European continent and a significant portion of Asia. The exact amount is impossible to determine but “400 times as much as a nuclear bomb” is a commonly quoted figure. This was 36 years ago; plenty of time for the effects to be felt and measured. And measured its been. The amount released is way over the “nuclear wasteland” threshold which we have been told time and again that no living thing could survive in the area for thousands of years.

The reality is nowhere close. Despite all the apocalyptic predictions the widespread death and destruction never happened. Thirty people died in the accident and its immediate aftermath. Despite releasing the largest nuclear fallout cloud in history. But, what about the long term radiation deaths and the nuclear dead zone around the disaster site? In the 36 years since the disaster there have been hundreds of studies of the effect all across Europe and parts of Asia and they have found a grand total of 60 people who died from the fallout. Not 60,000, just 60 in 36 years. They estimate that over the next 70 years this number could rise as high as 2,000. This is literally statistically insignificant. You were literally more likely to die from being struck by lightning than die from the fallout from Chernobyl.

Besides this, the nuclear wasteland around Chernobyl never happened, much less lasted for thousands of years. Some plants and animals did die from the fallout, but not all of them or even most of them. The exclusion zone around Chernobyl has become a de facto nature preserve. The forest is lush and the wildlife is thriving. A few people who owned property in the exclusion zone have moved back in and seem to be doing just fine. Unless you go into the reactor building itself, there is no evidence of any danger anymore. This completely contradicts everything I have heard about the long term effects of fallout.

There is one other major secondary effect of a nuclear explosion: The over pressure waves. The explosion superheats the air around and within it causing a pressure wave that cause hurricane force winds. The bigger the explosion, the stronger the winds. This shatters glass and can cause structures to collapse. This is not a sustained wind, but a single wave of pressure … but this is not the end. The superheated air rapidly cools creating a near vacuum at the site of the explosion. This creates a second pressure wave in the opposite direction that is almost as strong as the first. These spherical pressure waves are not line of sight and quite different from any natural phenomena. Hurricanes and tornadoes can produce high winds, but these are sustained and do not act like over pressure waves. High winds consistently produce results that cannot be reproduced in the lab.

Nuclear explosions can produce winds that if sustained, could flatten a city, but they are not sustained. Tactical nukes are unlikely to do much damage to well built structures and these are the most likely to be used in this context. The effects of larger explosions are unknown as there are no real world examples to compare it to.

The last thing that comes up when talking about nuclear explosions is the myth of the nuclear winter. I actually read the original book proposing nuclear winter back in the 70s. The text and illustrations all very carefully said that they were based on all nuclear detonations being made by lay down bombs for maximum fallout. This lead me to look up the percentage of nuclear bombs that were configured for lay down delivery. All sources I could find agreed that it was never more than 10% which meant that their predictions were already off by an order of magnitude. The basis for their theory was from the historical period known as the little ice age which attributed to the eruption of Krakatoa.

This theory was already on shaky ground when Mt. St. Hellens erupted and we finally got real world data on a major volcanic eruption before, during, and after the eruption. We finally had real world data on how much force it took to put ash into the high atmosphere, how long it stayed there and how much it affected global temperatures. The numbers weren’t even close. Dust just doesn’t stay in the high atmosphere anywhere long enough and a better review of the climate data showed that the Little Ice Age was already developing before the Krakatoa eruption.

(1) Everyone seems to love to talk about the “Tsar Bomba” like they know anything about it. In 1961 a pair of propaganda releases were made about a Soviet nuclear test (one US and one Russian). At that particular time it was to both sides advantage to play up the danger of the Russian nuclear threat. All actual data is still highly classified to this day. The only real things we know is that it was a really big explosion, and that the program was considered a failure and dropped. Therefore talking about the Tsar Bomba is irrelevant and all comments using it as a example will be deleted because it is about as relevant as a unicorn farting rainbows.

I previously identified third stage bombs as cobalt bombs. This was my mistake and I apologize. Cobalt bombs were an attempt to create a hybrid nuclear/dirty bomb with significant long term fallout. This only emphasizes that conventional nuclear warheads do not produce a lot of fallout as there would be no purpose I cobalt bombs if they did.

(2) The only other clue we have is the bomb’s public rating in tons of TNT. The only ones that know how accurate this are a few engineers that are not allowed to talk about on penalty of up to death.

(3) I'm aware of the plunger or gun type detonator, but this technology seems to have been abandoned as well and so is not relevant.

(4) People who refer to vaporizing flesh and melting rock (turning cities into glass) are talking being inside the nuclear fireball. Nuclear mines and lay down bombs are the only types where the nuclear fireball ever touches the surface. Nuclear mines are buried in advance and cannot be used offensively. Lay down bombs have largely been made obsolete by bunker busters. Lay down bombs were only deployed to destroy hardened, underground targets. The only cities that were ever targeted by these were capitols that had command bunkers under them, and these were only ever bomber deliverable, so not part of the first strike. They also had a significantly smaller damage radius than airburst bombs as line of sight was massively reduced. They were also the only bombs that produced any significant amounts of fallout. These are definitely the scariest form of nuclear bomb, but also the rarest. Getting a bomber over an enemy capitol is getting harder and harder. Parachuting a bomb from the bomber to the ground without it being shot out of the air is even harder. Russia has already lost this capacity.

Thousands of ground burst bombs used in a first strike on all major cities capacity was a nightmare scenario force fed to us without any basis in reality. Targeting ICBM silos that would be empty after a first strike was always a rather useless idea. All in all, its possible but completely impractical.

(5) Note on Electromagnetic Pulses (EMPs): Early radios were based on a phenomenon known as the spark gap. A strong radio wave when presented with a conductor with the right geometry (an antenna) would produce a noticeable arc of electricity. Radio waves are a type of radiation produced by atomic detonations. This is relevant because one of the first things found out by the atomic tests at the Bikini atoll (and elsewhere in the south Pacific) was that it was almost impossible to sink an armored warship with a nuclear airburst. A warship that has been properly locked down can survive a nuclear airburst and be almost completely combat effective … almost. Warships were made almost entirely of conductive materials (steel) and all sorts of surfaces became accidental antennas and produced minor sparks all over the place, including inside electronic devices like radios and computers. This tended to short out the more delicate electronic components like diodes. The Army noticed a similar thing with tanks and other armored vehicles. This phenomenon became more pronounced as electronics became smaller and more powerful. It only takes a microscopic spark within a computer chip to fry it.

The thing here is that EMPs, like most things about nuclear explosions, has been blown all out of proportion. EMPs only damage a few delicate components likely diodes and microchips (which are made out of diodes) and only if they have the right geometry to serve as an accidental antenna to cause a spark, and even then, fixing them requires replacing a few components. Nuclear fear mongers would have you believe that any electronic devvice within radio range of a nuclear detonation would be destroyed beyond repair, sending us back to the stone age. Electronics can be roughly devided into analog and digital devices. Analog devices are completely uneffected by EMPs. Digital devices can be, depending on how close they are to the explosion. Again the inverse cube law sets the range that things are effected.

So, can an EMP take down the power grid? No. Power generation is done entirely with analog machines. Besides this, lightning produces EMPs as well and the power grid is struck by lightning thousands of times a year. The few digital control devices are well shielded and have manual backups that that could be put back online within hours from even a direct hit from an air burst nuke. If you are in the same city as a nuclear strike, you could very well lose your electronics. If you are more than a few miles away, your devices are safe.

(6)The damage radius is where the nuclear explosion (A three dimensional sphere), intersects the ground (effectively a circle on a two dimensional plain). Trying to make calculation based only on the circle on the map leads wildly inaccurate conclusions. We do not live in a two dimensional world. Most of the time this can be ignored, but in this specific case you get the completely wrong answer if you do. Just like a 24″ pizza has a much larger area than two 12″ pizzas, A one mile diameter explosion is much more powerful than two half mile diameter explosions.

(7) Because the nuclear fireball is hundreds to thousands of feet across, solid objects may only provide partial protection to someone who is on the edge of a shadow. There is also the photoelectric effect that blurs the effect of the edge of the shadow. This can lead to people within the damage zone getting injuries similar to those in the edge zone that are not immediately fatal, but still end up killing them in the next few days or months.

TBC