Since I fucked up the math in channel, which drove me to spend half hour poring over the details to make sure everything's correct, I hurry to save the results here.
I. World Uranium reserves stand ati about about 6*10^9 kgs. Just about 0.72% of this is usable for the purpose. Uranium molar mass is ~250 [grams/mol] which means ~ 6*10^9 * 1000/250 * 6*10^23 atoms in total.
II. Energy output is ~200 MeV per fission event. The total ideally available energy is thus 6*109 * 0.0072 * 1000 / 250 * 6*1023 * 200 * 106 = ~2 * 10^40 eV.
III. Land surface is ~1.50 * 1014 square meters, so on average there's a total of ~1.3 * 1026 eV available per square meter, ~21 or so MJoules. This means that if there's water on the floorii, eight or so milimeters high, all-out nuclear war will dry it off.iii Guess what, the Sun does the same in an afternoon.iv Big whoop.
This, of course, provided you manage to mine all the uranium there isv, and manage to fission it in such a way that no atom escapes your wrath, and further provided that the sea is magically off limits to the enemy.vi
Consider also the problem of costs.
For one thing, the US total current arsenal is around 547 "megatonnes"vii, worth 4.1 PJoules or 2.6 * 10 31 eV each. Therefore the entire US atomic armaments (all 1.4 * 1034 eV's worth of it) come to almost 0.0001% of what's contemplated here. Provided, of course, they even work.
For the other thing, a single Trident missile (which is, as alf well points out, not at all the whole story) costs 30 to 40 million dollars, and delivers 15-20 TeraJoules, ideally. The delivery costs of fissile material involved in the Operation Dry Bathroom Floors would alone count for something like... 4 to 5 trillion dollars.viii The 2015 US budget is in total a shade under 4 trillion, so it wouldn't cover delivery. To get an idea of what this means : the US couldn't afford to pay for the taxi. Not the show, not the dinner, and definitely not the girl. Just... the taxi.
tl;dr Contrary to what is generally propagandized, there isn't a way to use nuclear weapons effectually on the field. The only effectual use for them is in mass media, for propaganda purposes. That's it.———
- It is important to note that Uranium is pretty much only found in the crust, and because it is principally an alpha emitter it is perhaps naive to imagine large deposits await unknown. Certainly much more naive than the same expectation about fossil fuel reserves, and last I checked that's not commonly held. [↩]
- Room temperature water costs about 2.6MJ per liter to dry off, and a liter of water stands a milimeter tall on a square meter surface. [↩]
- We're making the generous assumption that all that energy can in fact be transferred. This is ludicrous, of course. [↩]
- The Earth receives something to the tune of 200 PetaWatts from the Sun, and if the afternoon is four hours long this comes down to 2.88 * 1021 Joules, or 1.8 * 1040 eV. Same deal. [↩]
- Mostly in Australia. [↩]
- Which it very much isn't. In fact atomic submarines are by far the most hardy elements in case of nuclear war. [↩]
- Pro-tip : whenever someone's using some sort of "special" unit for banal stuff, it's because they're trying to scam you. [↩]
- Provided of course the supply of these things is absolutely elastic, and you can buy ten million for the same price you paid for one.
Actually, strike that : provided of course the US can even produce anything whatsoever anymore. I seem to recall a pellet of a billion or so dollars "lost" in Iraq, I seem to recall last the Pentagon humbly proposed to audit Blackwater the Grand Master of that wholly sovereign Templar order threatened to simply kill any auditors. I am altogether unconvinced that the USG can have anything it wants for any price. Period. [↩]