[kulkarnic]

The rational reason we don't build nuclear shelters anymore is because they're no longer effective. As weapon yields increased, it's become apparent that a concrete, underground hideout is not going to save you.

The irrational reason is that it's been 60+ years since atomic weapons were deployed, and we are confident the danger has passed. But really, there's plenty of weapons out there: http://www.motherjones.com/politics/2011/11/map-nuclear-bomb...

[hga]

Yields didn't really increase that much, there's a limiting factor where more and more of the energy released simply radiates out into space, and that's somewhere around 1MT as I recall.

A serious, concrete underground "hideout" will save you from anything but a really close hit; I can look up numbers if you want, but I maybe remember a good metric is 1MT and one mile of separation, requiring a less intense shelter. And a large fraction of the population can get by with much less, carpet bombing suburbia and exurbia was never going to happen, especially due to counterforce requirements and the Soviets believing that MAD was profoundly immoral and never buying into it.

[waynecochran]

An underground hideout was never going to save you if you were near enough to the blast -- I always thought it was more of a way to protect yourself from nuclear fallout -- wouldn't that still be a valid reason to build a shelter?

[kulkarnic]

Yes, you can save yourself from the fallout (which decays exponentially with distance anyway). Unfortunately within around 15mi, you're still going to get pretty bad burns, unless you duck into your shelter immediately after the explosion. That's where the early warning systems are useful-- you get 6-8min with an ICBM strike.

[Someone]

You don't need reinforced shelters against fallout; above-ground buildings will do fine, as long as they can be made reasonably airtight (as additional protection, one could provide for material to replace broken windows)

Also, I think most shelters would be far enough from blast areas to provide some protection.

Eizo Nomura (who, amazingly, doesn't have a Wikipedia page) was 170 meter from ground zero in Hiroshima, and survived (http://en.m.wikipedia.org/wiki/Atomic_bombings_of_Hiroshima_...)

Akiko Takakura was above ground at less than 300m and lived for 60 years.

Even though later bombs were much more powerful that makes it likely that shelters at the edge of the blast radius can save lives.

Not all of them, but any program to protect civilians is a statistics game.

All the construction in SF isn't 100% effective against earthquakes, either.

[hga]

Per Cresson Kerney, who's nuclear war survival stuff was actually tested against reality (vs. the deathtraps like at least one of those early shelter plans in the OP which was dreamed up by D.C. bureaucrats) says air tightness concerns are entirely overblown, so to speak ^_^. As I recall, the heavy stuff that falls out early is too big to be a concern of that sort, the light stuff decays to safe (enough) levels before enough of it drops and becomes an issue. We have a lot of data on this thanks to those eeeevil above ground tests.

What you need is plenty of mass between sources of radiation, i.e. fallout particles where they settle, and from "skyshine". In a sufficiently bad situation, which would be pretty common, a simple ditch where you made sure the fallout kept out and didn't accumulate on, say, the tarp you were using for that, you'd still get zapped by gamma rays that bounce off atoms in the air and come down into the ditch.

So the most basic expedient fallout shelter is a ditch with hollow core interior doors over it or the like, and foot of dirt on top, which through arching holds most of its weight.

An above-ground building is iffy, because you want, say, 3 feet of dirt all around you, and either a foot on top or if the roof is high enough that's not as much of an issue. Middle stories of a tall building could suffice.

[ZanyProgrammer]

No, a shelter is a perfectly valid way of surviving a near miss-being 20-30 miles away, you'll want a shelter.

[hga]

More like 2.3 miles for a 1MT airburst, that's just for a 15 PSI blast shelter. If you're building these for real, with concrete and so on in a real Civil Defense program, that's easy. It's pretty easy, if you have the time, to build an expedient blast shelter with wood and earth that'll handle 15 PSI.

And most warheads are less powerful (see my other comments); using my handy "RAND" nuclear effects calculator from the back of my copy of The Effects of Nuclear Weapons, 15 PSI for the following weapon air bursts (targeting cities, not ground bursts against ICBMs etc.):

  500 Kt: 1.8 miles
  300 Kt: 1.5 miles
  100 Kt: a bit over 1 mile
   50 Kt: 0.85 miles

So we're really talking a mile or two, depending on the standards to which the shelters are built. 1 MT 1 mile requires 45 PSI, call it 50 per the above. Don't know how intense a real shelter would have to be, then again that's an uncommon threat level.

[Retric]

10,000 nukes * pi * 30mi ^2 = 28,274,000 square miles.

The lower 48 states are only 3,119,884.69 square miles if you inclde waterways. With just land it's only 2,959,064.44 square miles.

So, 10k nukes let's you carpet bomb the lower 48 and have one within 10 miles of just about every point. Focus on population centers and I suspect you could easily get 95+% of the population within 5 miles of a detonation.

[ZanyProgrammer]

Where do you get 10K nukes (Russia now? Soviet Union circa 1984?) Do you mean warheads or delivery vehicles? Do you assume that every one of those 10K will be delivered to the lower 48? Or that every one of those 10K will be successfully launched and reach its target? That there won't be any out of commission for maintenance or second strikes? Or that a western pre-emptive strike won't hit any? Or that there might be BMD systems that will make an incoming strike suffer attrition? Are you factoring in that some targets will get much more than a single warhead?

[Retric]

That was just a nice round number. According to Wikipedia from ~1970 - 2000 Russia had 10,000+ nukes with a peak of ~40,000 in ~1985. No idea what the actual numbers where though. http://en.wikipedia.org/wiki/Nuclear_arms_race

Mostly, I was just pointing out that fairly soon they could branch out and target just about any population center. I don't think they ever actually targeted death valley for example.

Anyway, the important thing to remember is by the mid 1970's many of these bomb shelters had been unused for 20+ years. It's very natural to look at something like that and say spending more on this is probably pointless.

[rhino369]

The Soviets never had 10k strategic weapons. And even big strategic nukes (5MT) would not have a lethal radius of 30 miles. Even if you were outside, naked and facing it.

A well built bomb shelter would be very effective at reducing the lethal range of nuclear weapons.

Most of the stockpiles during the peak of the cold war were tactical nuclear weapons with low yields designed for the battle field.

[masklinn]

> The rational reason we don't build nuclear shelters anymore is because they're no longer effective.

The rational reason we don't build nuclear shelters anymore (which is not actually true by the way, Switzerland still builds them although they're not required anymore for private residences) is because there's very little chance of a massive nuclear war which is what they were for.

> As weapon yields increased, it's become apparent that a concrete, underground hideout is not going to save you.

Weapon yield has decreased, not increased. In the 50s, delivery was through bombers, you wanted big bombs because many bombers were going to be shot down so each nuke delivered had to pack as much punch as it could. Early ICBM had similar-ish issue, you had few inaccurate rockets and they had a warhead each so each warhead had to count, you built a big rocket and a big warhead on top of it, and the ones that didn't fail and weren't shot down razed a city even when they missed it by tens of miles. That's where you had multi-megaton designs

With the 60s and MIRV multi-megaton went online (they'd been designed in the 50s) but systems designed in the 60s and deployed in the 70s for the exact same role all went sub-megaton, half a megaton at most, usually less, for smaller and more precise delivery platforms and MIRV systems.

The most numerous warhead in the US nuclear arsenal is the 100kT W76.

[ErikRogneby]

Here is a pretty well built companion tool for looking at blast radius. http://nuclearsecrecy.com/nukemap/

[jules]

That does not make logical sense. For any given nuclear weapon that doesn't kill the entire planet there is a range from the epicenter where a bomb shelter is effective, regardless of weapon yield. Yes, the area where people are killed even if they are in a bomb shelter is larger, but the area where people are saved by a bomb shelter is larger as well.

[dba7dba]

Some may disagree but the reason we did not have WW3 was because of nukes. Had there been no nukes, I firmly believe we would've had WW3 (or even WW4).

Because both leaderships of US and USSR knew starting WW3 would mean end of civilization on the planet, they controlled themselves.

[alan_cx]

I thought that was the whole point of building lots of nukes on both sides. They called it MAD, mutually assured destruction.

[hga]

That was never the Soviet's game, they planned to win if it came down to it, and note all the mentions of 2nd World shelters in this discussion for part of that plan. I've also read a translated version of their basic civil defense book, it was good.

MAD was insanity cooked up by Robert Strange McNamara and company of Vietnam infamy in the early-mid-60s. The Soviets never bought into it, and thought, correctly, that a plan to burn alive children in their homes was irredeemably evil, and a sign the US was very evil. And at this level it was and still is.

[dba7dba]

What do you mean by Soviets never bought into it? Did they think they could win without themselves being destroyed by American nukes?

[hga]

Yes.

Although emphasize could, it was hardly certain. (And if this strikes you as crazy, well, remember that since a little before 1920 they explicitly were planning on taking over the world, and got uncomfortably close to achieving that goal.)

This was one of the reasons SDI, even on paper/in the lab, was so terribly effective. Against an even partly effective ABM system a counterforce first strike becomes impossible, since you can't choose which warheads or boosters get intercepted.

Counterforce is an attack on your opponent's strategic forces, aimed at preventing them from retaliating. That's one of the reasons we had to build the expensive "Triad" of ICBMs, SLBMs, and manned bombers. Reliably taking all three out is very difficult.