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Why MIRV?

I came across this post from DesperateDan who posted this excellent prose on SA’s AIRPOWER/Cold War thread. Without further ado, I present DesperateDan’s
Nuclear Weapons/Trident Effortpost II – Cobalt Thorium G Edition.

–The Management

A brief introduction to your eventual destruction

The first few fission based nuclear weapons were relatively small in explosive yield, but with early cold war paranoia, mankind’s never ending passion to murder each other, and lots of research money, large fission then fusion devices became possible. We went from Experimental devices of 15 kilotons that devastated Hiroshima to 15,000kt (15 Megaton, Mt) production line bombs within a decade. The early ICBM’s were very inaccurate (within a mile or two of the target was good, if it even got there), so having a vast explosive yield was really important to scoring a good hit, and any precise work or follow-up would be carried out later on during the apocalypse by nuclear armed bombers capable of greater accuracy (or by throwing loads of missiles and hoping for the best, or both, or both and a covert team with a backpack nuke – the cold war was insane). As the cold war continued, missile accuracy kept increasing, and so did “throw weight”, how much could be carried.

But really, really big warheads, while utterly devastating, are actually really, really inefficient- let’s say you throw a 9 Megaton (9,000kt) warhead at a city- it devastates a lot of that city, but if you instead launch 8, 100kt warheads on that same single missile and spread them about with great accuracy to the vulnerable areas of a city, you can do far more damage, and you only used 800kt’s worth of precious weapons grade atomic sheeeit, that you can instead throw into more warheads.

Only Russia and the US keep anything really large anymore, and few of them. Why? For literally digging out the mountains that each side buried their command and control systems in. You don’t need to bunker-bust (although nuclear bunker busters have been developed) you simply dig, dig, dig with dat atomic fire. Really- if the mountain won’t come to Mohammed, he just takes the top off like a freshly boiled egg.

Anyway, it sounds counter-intuitive, that I use less than 10% of the force and yet achieve more destruction. How the hell does that work eh?

As my first act as Mayor of London…

Well. Charity begins at home and all that.

Let us airburst a 9 Megaton bomb over the London eye, at just the right height to make the most of it.

Well okay, that looks pretty effective. But what do the rings actually mean?

At pretty much light speed the outermost ring will have many fires start on susceptible materials, people exposed to the explosion get third degree burns, it’s going to be a shitty time for anyone exposed- they probably won’t be able to count on much of a fire brigade to help either. Building damage, by the time the blast wave comes, is all but minimal bar glass starting to break maybe about two thirds of the way into the outermost ring (with notable blast damage to buildings starting and increasing from here), and hence most people in buildings in the outer zone have good protection from all aspects.

Next ring in (the vaguely grey one about halfway in), the blast pressure from the warhead is 5 psi and above, things start getting super shitty for people indoors. Buildings don’t like 5psi at all, you can probably expect high fatalities in your average exposed council house, because broken and smashed in houses are guaranteed, and the contents of those will feed the firestorm that will soon rage there. Thick concrete building? Well, that’s probably not much protection by 10psi. Next ring, 20psi, just stop worrying about any chance of survival or any of the gory details from there on in. Now it’s coming out.

What does that mean for attacking what makes London a useful city

Well that strike kinda sucked really, when you consider the power you unleashed. London City airport and Heathrow are both gonna be damaged but still largely functional very quickly (damn the terminals, a lot of the function is the long stretches of runway, which are hard to kill), you just lost a lot of governmental buildings and a lot of people, but largely, a lot of what’s left of London’s docks and industry are relatively unscathed.

I also used the word “exposed”. London is really built up so there’s a lot to absorb the shockwave – somewhere like Wembley, with a lot of built up area in between will have noticeably less damage than equally distanced Kingston on Thames, because Wimbledon common isn’t a great shock absorber compared with concrete and brick. The reason Hiroshima and Nagasaki got so fucked over with tiny (15kt and 21kt) bombs had a lot down to the wood and paper buildings being taken out entirely with the kind of blast/heat that your average council house would laugh at (outer part of the yellow zone) – concrete buildings in Hiroshima and Nagasaki survived close to ground zero (because really, 15-20kt is small).

What about a bunch of smaller nukes on one missile, like you said before?

So let’s airburst a 100kT device over the London eye, see how that looks.

Well, that was really quite shit compared to that 9 Megaton beast, wasn’t it? That’s why we packed 7 more on this missile, though. Let’s MIRV it up.

Zap! Kapow! Whammo!

That still looks like a LOT less destruction at first, but lets look closely… fuck, there go both Heathrow and London City airport that we failed to kill last time, and there goes any chance of London being used as a port for a very long time- all obliterated in concentrated blasts. I could even make groundbursts in selected areas just to make super-duper sure of harder targets if I wanted. I then just stuck the rest of the warheads on large industrial looking areas. I probably killed less people outright than the 9Mt blast, but killed a lot more infrastructure and production. The remaining people have other concerns too, like being wounded and/or on fire in a city that’s largely on fire and ground zero for fallout.

Fallout: Londons Burning

I probably don’t have to explain that all the radioactive materials used here are also not particularly pleasant to have around- a lot of what was in the bomb is now a variety of exotic, highly radioactive elements, and the nuclear explosion itself created even more through neutron activation- where the initial radiation blast transmutes friendly everyday elements into their isotropically devious brethren. All of this highly radioactive soup is mixing in with the boiling hot dust, soot, branches of Gregg’s, steam and ashes that used to be 8 parts of London and it gets carried up far into the stratosphere, from where it will rain cancerous death. Oh, and most of what makes a modern city is pretty flammable and toxic/radioactive/fucking rank/carcinogenic/mutagenic when burnt, and a lot of it’s on fire – and don’t forget all those chemical plants, oil refineries/depots, all especial nuclear targets. This all blows steadily away on prevailing winds, and if you are downwind, you are in for it in a really nasty way.

Lets look at a fallout map of the 9Mt hit on London.

This is an idealised plot for rads per hour that has the wind blowing with a constant speed/direction e.t.c- a real life one would meander a bit, but the idea to remember is that it spreads out in this flame effect. The outer ring of the massive turd laying over the nation? 1 to 10 rads per hour. Any dose is bad, but 1-10 per hour isn’t too bad on the scale of things here- increased cancer risk e.t.c, this is where the protect and survive shelters might help a fair bit. As you go in from there, that’s where you start getting significant, prompt radiation sickness. 25 and above and you start seeing radiation burns. The third ring in? that’s where you start looking at 100 rads per hour, which is kind of unhelpful given that 3-400 rads in a day is where you start dying by shitting and puking your innards out. Next one in? 1,000 rads per hour. A 1,000 rads in a day is lethal in almost all cases, and that dose is happening in an hour. The last ring? 1750 rads per hour. Proper fucked, before ze Germanium gets there. Nukemap won’t model accurately above that and to be honest there wasn’t much point above 1,000. The half lives of the real nasties ranges from a few days to a few years (remember, anyone trying to scare you with “radiations that will last for millions/billions of years” (as often heard around nuclear power/waste processing) is an idiot, elements are scary when they are pissing themselves away in a few days or months and letting the energy out promptly- like the above picture).

Fallout is something that can be prepared for quite well if you are in an intact house, and you can stay there for a few weeks – it’s the ashes and particulate that are “hot” radioactively, so if you can put as much stuff between you and that as you can, figure a way to not breathe particulate and sit around as long as you can while the nastiest stuff decays away, it’s not much of a concern over a scale of days and weeks of living, but you now run a phenomenally high risk of cancer (and all those other pesky concerns of post nuclear holocaust Britain, like having to fend off rad-foxes and mutant badger-guai while munching squirrel on a stick). The poisons from the smoke of all the stuff that’s burning, that however can’t easily be avoided without filtration systems though.

But that’s assuming one city. Something like this happening to tens or hundreds of large cities throughout the world would probably be enough to approach full-on nuclear winter. That in, and of itself is a thorny issue – there isn’t a great deal of useful data, a lot of potential scenarios and so hence a great deal of speculation – but that speculation seems to broadly range from a “well, with a regional, limited nuclear war, we might only be like 60-75% fucked”, to “oh, look, we made a radioactive ice-storm planet”. Regardless to say, the damage threshold for global consequences is low, and the number of targets and nuclear weapons very high. Crops might not grow at all for years, or decades for anything like proper growth, and when all the crap did finally fall out of the stratosphere, the damage to the ozone layer would have been phenomenal, and now the Sun will be frying everyone with massive UV levels.

So what the fuck is Trident anyway

Trident is the UK’s current Nuclear weapons program as a whole, and the name of the missile carried (UGM133- Trident II) on the 4 Vanguard submarines (HMS Vanguard, Victorious, Vigilant, Vengeance – at least the names aren’t half bad, but as a navy without an extant HMS Gay Viking we should hang our heads in shame). Each can carry 16 submarine launched ballistic missiles (SLBM), and each missile is technically capable of carrying 14 warheads, the START 1 treaty limits deployed warheads per missile to 8. Each missile has penetration aids (“chaff”, fake radar emitters and mylar balloons etc to fool radars, stealth coatings applied to the MIRV bus), and it’s likely that each warhead spot not used on a missile has a fake warhead- all to limit to efficiency of anti-ballistic missile systems. Range of the missiles is 4-6,000+ miles depending on how many warheads are packed, with an accuracy of around 100 metres. Range of the submarines is limited only by food stocks and maintenance requirements- it’s possible for them to sail around the world submerged multiple times.

The warheads are UK built from US/UK designs, and there are around 180-200 cores and assemblies available (an exact number is impossible to find), with around 140-160 built weapons at any time. Explosive yield is variable with three selections – 0.3kt, 5 to 10kt and 100kt are available by a flick of a switch. Building more is technically very easy, as a large stockpile of weapons grade material exists (there was once a much larger stockpile of weapons, and the material in them is still stored away) – all that remains is putting it together correctly. The missile stock is shared between US and UK submarines, with the UK having a supply of 58 or so at any time. This is the closest the US comes to any kind of control- if they breached the agreements and withheld missiles the UK would be stuck with the 58 currently held, and make their own servicing arrangements/replacement missile.

Normally, 1 or 2 submarines are on operational patrol, with 1 or 2 training and a further one on refit/shakedown. Currently less than a full loadout of missiles and warheads (8 missiles, 40 or so warheads) are carried, but that can change very rapidly if required – Trident was just coming into force as the first cold war wound down, it was designed with a lot more destruction in mind, and all the key pieces to vastly increase the destructive power are intact – technically, two submarines could put nearly 450 warheads on target, assuming full missiles on full submarines.

Important note – having less submarines, as some have proposed to reduce costs, has an obviously dramatic effect in how many missiles you can throw around, and exacerbates any problems with maintenance, or the chance of losing a sub to unforeseen circumstances. The cost of a submarine itself is around a hundredth of the cost of trident as a whole and hence it’s somewhat of a lame-duck option- you don’t save much and you lose a lot of capability.

Ok, so how does it get used, and how effective is it?

In short, the people who are right now in control of the UK’s nuclear weapons are the Submarine’s Captain, the XO, and the weapons officer, on each deployed submarine. If all three of them agree, they don’t need special permission or anything like that, they pick targets, unlock a safe for the codes and they launch missiles. Now, technically, they should be waiting on release of the weapons, and some idea of where to fire them at. But I just want to make it clear, that right now in relative peacetime, that operational control is already at the hands of the submarine itself- that’s rare compared to other services, but makes sense given it’s largely a second strike force, and the sole remaining part of the deterrent.

Now, let’s say a PM, or their elected “other” decides they want to bust out the nukes in response to the perfidious Soviet threat. Military aides work with them to choose targets and yields, and then this is communicated to a Royal Navy base and then to the submarine/s by undersea magic and authenticated with codes held in the safe.

Otherwise, in the event of being unable to contact any part of the chain of command for a set period (and yes, being unable to get radio 4 is part of the apocalypse) they get to open up the letter of last resort (like that fucker didn’t get steamed open on the mess kettle 15 mins after sailing). This is written by the PM and will give options upon armageddon ranging from “AVENGE US” to “give yourself up to the UN/US/Immortan Joe/The RSPCA”. It isn’t a detailed set of targets, the Captain and XO would be given free reign to retaliate (or not).

The UK holds a small nuclear arsenal, but it’s far more than sufficient to render 10 large cities useless, and hence, seen as it can be launched reliably in a second strike (submarines are ace for this), it’s more than a capable deterrent force. With 2 attacking submarines you have 32 missiles tubes available, and only enough warheads for around 20 so you can spread those warheads out over the 32 total missiles, and you suddenly have lots more room for more penetration aids/fake warheads that further lower the effectiveness of ABM shields, but only about half the warheads need to make it anyway to give us the kind of strike we got on London, on ten different cities or smaller strikes on more cities/military bases/industrial assets/porn stashes/whatever. There’s a whole lot of talk on counter-force, counter-value e.t.c but to be frank, it’s boring and can just be boiled down to attacking purely military targets, industry/population (they tend to be intertwined) or both. It’s the capability to do so that matters to MAD.

To be a viable deterrent the nuclear forces need to be just strong enough- no need for too much overkill. Strong enough for what? Strong enough for MAD. It’s worth pointing out that all other Nuclear armed nations other than the US/Russia only hold deterrent level quantities (or three tenths of fuck all nukes, like North Korea presently possess).

Are you MAD?

MAD. Mutually Assured Destruction. It works real good until it doesn’t work, and then things turn to shit in a major way. To have MAD, each side must be convinced the other side can strike back with crippling force, no matter how good the initial strike by the aggressor is. Hence, second strike capability must have two attributes – redundancies to allow it to be fired in retaliation even if the command and control system is dead, and protection/number of warheads necessary to ensure that a strong enough deterrent gets through. In the UK’s case, this amounts to the letter of last resort, having submarines on constant nuclear patrol, and having a combination of warheads/number of decoys and penetration aids/other classified magics deemed enough to work their way through an ABM system.

While the UK has never renounced a first strike, the entire set-up is a perfect second strike, revenge system. It’s range lets it serve as a first strike weapon though – if I was going to do that, however, the subs would close in as far as possible to the target first, as reduced flight times are reduced warning times. But no nation holds enough warheads for a “proper”, all out strike with any hope of crippling the enemy enough to prevent retaliation- that would break MAD anyway.

Assuming MAD holds, no-one wants to start a nuclear exchange, because no matter how well they hit first, they might as well have nuked all their own best cities anyway.

What that also means is, if MAD breaks down and a nuclear exchange begins, it’s very easy given the disruption caused to command and control that contingency plans (like the letter of last resort, other nations have their own contingency plans/systems) would go into place, and very large numbers of weapons would quickly get used both by the aggressor and responding nation. Then we get a situation where “Threads”, frankly, looks like the palest imaginable shadow of the true horrors that will unfold.

MAD is unlikely to break down through the ways wars traditionally start – for this we can look at the cold war, the only time both sides belligerently ramped the tension quite to the edge was the Cuban missile crisis (for example, 2/3 of the command crew on a Soviet nuclear armed sub, thinking that war were declared, wanted to waste a bit of the US blockade with a nuclear tipped torpedo rather than die to depth charges but surfaced instead to find war not declared just yet). But, on many, many other occasions, human and mechanical fuckups almost triggered an accidental release of weapons- or worse, during a time of tension, one side misinterprets the others intention, sees a hostile strike as all but certain and then plans a pre-emptive strike, like Able Archer in 1983 – the Soviets were certain NATO was gonna go for the throat, and they got ready to launch, or a few months before that when Stanislav Petrov bravely stuck a wrench in the gears of a Soviet Nuclear warmachine under false indicators of attack. There are literally dozens, if not hundreds of small and large events that could have already led to the apocalypse, they just weren’t lined up right- but like the Swiss cheese model all that needs to happen, essentially is time.

As time progresses, especially as the second cold war is getting well into pace, more incidents will happen, and again and again the world will have to trust to chance and circumstance that it doesn’t turn to the apocalypse by idiotic accident/over-reaction.

That, and MAD only holds out for certain situations – if a state gave weapons up to other groups that then used them, it may be unclear as to who supplied them initially (it’s feasible that detailed radiological analysis could point towards where the weapon materials were mined/refined, but that would take time) which could cause a confused response. Conflicts like the cold war between Iran and Saudi Arabia, where there are many factions in play, could be a horrific mess if it turned hot, especially if control/security of the weapons isn’t very closely maintained.

Report to the vault overseer, hardworking Briton who got on in today’s up and atom world

So what happens afterwards? All this gets used and the world burns, fallout poisons vast swathes of what didn’t get burnt up. Nuclear winter happens to whatever extent it does. Some nations won’t be as badly hit depending on how bad it happens, but in the turmoil afterwards I could easily imagine more wars between emergent/remaining powers over the scraps of good territory/resources that are left. There certainly wouldn’t be much taboo to stop them turning nuclear too. Civilisation as we know it certainly dies, perhaps even as a globally connected civilisation we fade away for awhile, but humans are spread all over the globe in some pretty remote places- I can’t imagine an outright holocaust of the whole human race, but I can imagine it being hundreds to even thousands of years before we start to approach the same kind of level of civilisation we have now, and certainly a death knell for many animal/plant/fish species.

The government has detailed plans of how to continue government in the event of pretty much anything (the first priority of a state is to ensure the survival of the state), but in an all out attack the UK is a crowded isle with many targets and little is likely to survive. Very little money was ever put into UK civil defence in the event of a nuclear war even from early on, and few nations ever did (Switzerland is a key example of a nation who spent, see the further reading list). Top level government/her royal madge had/has multiple plans including living on ships and staying constantly on the move – quite early on it seems to have been realised that no bunker was ever going to be strong enough or secret enough to keep anything truly safe, large scale blast/fallout shelters like BURLINGTON were abandoned before they finished in favour of a larger network of smaller, less important/vital deep level bunkers and special arrangements for anything else (in Burlington’s case, the KGB knew exactly where, what it was intended for, and how many megatons to kill it even before work even began).

Civil defence could work well to an extent theoretically (given investment and time), some of the stuff in “Protect and survive” is valuable stuff for staying alive for awhile before dying from the longer term effects – if you are in areas it would work (I.E. out of the yellow circles, not in a severe fallout zone). If you were anywhere near a target, it was busy work for the hours before the apocalypse. Furthermore, there presents somewhat of a paradox- if you invest heavily as a nation in the capacity to survive a nuclear war better, you may be targeted more or have your civil defence capabilities picked out especially for destruction- MAD abhors a vacuum. If the nuclear war is large enough, then there isn’t any real point in keeping people safe from the heat and blast only to have them inevitably die from radiation or starvation in the following weeks anyway.

From the war plans we know of, government would hand power to what would essentially be regional governments – formed from the personnel of whatever bunkers survived – who had the power and sway of an angry old testament god – all property would be the government’s, death penalties for minor crimes, sick/disabled people starved to death (even more so than normal), prisoners in jails to be released or shot (prisons tend to make good fortresses that are often slightly off the beaten track, with plenty of spartan accommodation) even lists of undesirables to be eliminated – the full dictatorship package.

But don’t worry. You will probably be dead long, long before then.

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