Qfyilyi

So, in my world, a nuclear war engulfed the Earth in the autumn of 1962. It is now the year 2568. In my story, a cult of mutants known as “The Followers Of Uranius” have sprung up in Kansas City. Their leader, Derryk, is convinced that the nuclear warhead inside of a silo is a holy divine being, and that he must act as its prophet. The Followers eventually get conquered by the Empire up north, but Derryk has different plans in mind. Not wanting to see Uranius fall into the hands of the empire, he activates the bomb, and within secon-

The Followers, Imperials, Derryk, and Kansas City are all vaporized in an instantaneous flash of heat.

So, my question is, would it be possible for a nuclear warhead to stay usable for that long (a period of 600 years)? If not, is there any alternative that I could use?

-The Followers don't actually live in Kansas City, they just think they do. They are actually farther out in Missouri, and just call their settlement Kansas City

No, on a variety of fronts

So, first of all, there's no nuclear warhead ever developed that will last six hundred years, for a variety of reasons:

1. High explosives (required as the triggering device for the nuclear weapon) degrade quickly, even when stabilized versions are used. RDX (the C-family of explosives) has a recommended shelf life of five years. Even the most optimistic chemist wouldn't give you more than fifty years of reliable behaviour from a plastic explosive, and you need exquisitely reliable behaviour for a thermonuclear detonation.


2. All the ICBMs in 1962 carried thermonuclear warheads (because the things weren't nearly precise enough to use anything less). Tritium is an essential component in a fusion weapon - and it has a half-life of 12 years. That means that, depending on how overengineered the weapon was to start, in as little as 6 years without maintenance, the bomb would only produce a fizzle yield.


3. The lensed charges (fission bombs) required to create a thermonuclear yield use a particular crystal structure in their plutonium to achieve a "shaped charge" effect. (With a lot of room for error, obviously). Six hundred years of heat (from radioactive decay) and the decay itself would probably wreak havoc on that structure.

So, the high explosives won't work, and if they did, the fission devices probably wouldn't go off, and if they did, the decay of the tritium means that you'd have a blast measured in kilotons, not megatons. Multiple failures resulting in a dud bomb.

Beyond that, there are other issues.

In 1962, there were at most 126 silo-launched ICBMs (page 65). It seems unlikely that in an all-out nuclear exchange, any of them would be left on the pad. If any were, assuming your counterfactual world is the same as ours up until 1962, the closest silo to Kansas City was the Atlas site in Valley Falls, 60 miles out of Kansas City. Even a full-yield blast (4.5 Mt), not accounting for the effects of going off in the hardened, heavily-armoured silo, wouldn't touch Kansas City.

That last is for two reasons - one, no nuclear war planner wanted to store high-yield weapons inside major US cities, because if an accident happened, you wanted it to happen out where no one lived. Second, no nuclear war planner wanted to store strategic weapons in a major city, because the weapons would be a first-strike's obvious first targets.

So for an enormous variety of reasons, the scenario you've described wouldn't happen.

Short answer: no.

The first hurdle you will encounter is decay of the radioactive elements used in the warhead. For a modern thermonuclear device, the main component to worry about is tritium, which has a half-life of only 12 years. Nuclear warheads need their tritium replaced periodically in order to remain viable. However, you can use a more primitive fission warhead - something using uranium-235 (half-life: 700 million years) or plutonium-239 (half-life: 24,000 years) will still be intact. This isn't as massive a detonation as you're envisioning but it's still nothing to scoff at.

However, the second problem is one of triggering materials. There are two main ways to trigger a nuclear detonation. One is to have two subcritical masses and ram them together really quickly using a (chemical) explosion. The other is to have one subcritical mass and compress it using the shockwave of an explosion. You'll note the key shared word there: explosions. You need chemical explosives to be able to produce the prompt-critical chain reaction to cause a proper detonation.

However, chemical explosives are not shelf-stable over very long periods of time. Even totally isolated from the outside environment, they very slowly decay into more thermodynamically stable (read: non-explosive) forms. Other answers suggest that for conventional explosives such as regular ammunition, you're looking at a period of decades rather than centuries before they're useless. You could salvage the radioactive elements from such a bomb to make a new bomb, but you couldn't detonate it as-is.

Third, as @AlexP points out in comments, there are safeguards built into the design of nuclear warheads to prevent these sorts of scenarios. For instance, there may be an altitude sensor that prevents the warhead from arming until it passes above a certain altitude, or an acceleration sensor that prevents it from arming unless subjected to extreme acceleration - both of these are designed to keep it from going off unless it's attached to a missile and properly launched. You could, of course, override these sensors with care and ingenuity.

Yes, if...

Yes, provided it's not a modern device, for the various reasons outlined in other answers, plus that these devices are designed to fail-safe – if anything isn't working perfectly, you'll not get supercriticality. Even if all the firing circuits were still working perfectly, and he had codes that were still valid, there's absolutely no chance that the conventional explosives used to trigger them would perform as expected after that long.

Key to this is that modern devices don't have enough fissile material to create a critical mass – they rely on an explosive lens imploding a sub-critical mass to a higher density at which it becomes supercritical. That requires powerful, precise and specialist conventional explosives, including very precise timing (computer-controlled, I believe). This is partly for cost – fissile material is expensive – and partly as it's a failsafe – it makes it extremely difficult to detonate it not only accidentally, but even deliberately if you can't activate the firing mechanisms.

But...

But, if the device was a much simpler one, then yes, it could still work.

A gun-type bomb such as the 'Little Boy' used at Hiroshima is very basic. Two sub-critical masses are pushed together to create a supercritical mass.

U-235 has a half-life of 703,800,000 years; Pu-239 24,110 years. So even after 600 years, a little boy style device would still hold enough to create a critical mass.

Obviously the original explosives would have deteriorated, but as these devices are much simpler, you could replace them with whatever simple explosives are available, or even with a good hard shove with a hand (it'll hurt, but only for a microsecond, haha!).

You won't get anywhere like the full yield, but you'd still get a fission explosion. Depending on the original intended yield, that could still be plenty.

So yes, a functional nuclear device could last that long, though not the style used by major players today.

But...

But there's no 'little-boy' style devices around today that we know of, though it's possible that North Korea or other smaller nuclear powers are using such devices.

So you'll need to add something to your history, to posit a scenario where prior to the fall of the nation who created the nuclear weapons, they switched back to simple devices.

• Perhaps this is due to cyber-warfare – they decided that any computer involved in detonating a nuclear weapon was a risk, so reverted to much simpler devices which can be triggered manually or by a simple chemical or clockwork fuse.


• Perhaps the factories or other infrastructure which was needed to produce some of the components were lost, forcing them back to simpler devices


• Perhaps a general/etc. was a bit paranoid of either of those scenarios, and got some simple devices manufactured 'as a precaution'


• Perhaps the device was captured from NK or another such nation, and brought back to be investigated and/or dismantled.

None of those seem particularly unreasonable options if there were a protracted conflict resulting in a nuclear war, the setup to your book.

However, it seems less likely that this type of device would be used on a (high-technology) missile. Potentially the missiles were reverted to older tech too, or perhaps only the bomb-making infrastructure was damaged, not the missiles. More likely, the devices were not installed on a missile, but were intended for use as a parachute bomb (Hiroshima), or a mine; they were just stored in an easily defensible silo for security.

Another problem with this scenario is that in an all out Nuclear War, keeping a missile siloed is not a viable option. Silo based missiles are one part of a "Nuclear Trifecta". A country achieves the Trifecta when they have nuclear arms that are deployable by ground based platforms (silo missiles, mobile missile sites (USSR/Russia)) air platforms (Gravity Bombs dropped from air planes... often the first possible delivery vehicle any country can use... certainly the most reliable by your time frame) and submarine based (the last of the trifecta, usually and only reliable second strike method). There are also two phases of an all out Nuclear War: First-Strike and Second-Strike. First Strike denotes the first en-mass nuclear strike and all missiles are launched immediately. It's pretty much the salvo that turns a conventional war nuclear. The Second Strike is the retaliation from the attack of the first strike and is normally launched as soon as a first strike is detected.

The goal of the First Strike is to eliminate a Second Strike before a Second Strike could be launched. Thus, targeting the ground based weapons (silos) was critical to any First Strike planning. It's estimated that no matter which side launches first, the first strike will 3% of all Nuclear missiles capable of Second Strike retaliations on the enemy side. Most of these would be Ground Silo and Air based missiles (mobile Launch Platforms might survive, but Global Thermonuclear Warfair is played very much like Horseshoes: Close enough counts). Subs are stealthy enough and mobile enough (and can move over a larger area) that they are only Second Strike vessels and will survive a First Strike Launch.

For this reason, a Silo based nuclear missile will either be launched immediately or fails to launch and is destroyed by an inbound missile. Additionally, given the secracy of the Subs, siloes are more visible in nuclear deterrence propaganda. Second Strike goals are not so much to obliterate the other side as they are to deter the other side from making a First Strike, as the destruction is mutually assured. It's M.A.D. but hey, we're here and not dying in a nuclear waste land. It's assumed they would get spotted pretty quickly by intel, so they aren't the best hidden sites and for good reason. The U.S. and the USSR both believed the other side was far out performing them in production of delivery vessels. The so-called Bomber Gap and later the Missile Gap, were both issues that featured heavily in Truman, Eisenhower and Kennedy's campaigning. Russia had a more concerning but similar issues, as they knew the U.S. claim to the loser in these gaps were through their own deception and they were really behind and needed to close the gap.

Suffice to say, once the bombs start flying, survival of any bomb is highly unlikely. It's either going to hit something or get hit before it can leave it's silo.