Just for fun, it might be interesting to look at what a nuke down hole might do at the extreme. IANAGP. Lots of rough and ready numbers.
Assume a pretty big nuke - 1 Megaton = 4.2 x 10^15 Joules.
Pressure at 10 km depth - 2.7 x 10^8 Pa.
Assuming the depth is large compared to the size of the bubble we are about to blow in the crust, we assume constant pressure from above. Ignoring energy lost to fracturing and heating rock, a limiting case is:
Volume = 1.5 x 10^7 m^3, or a bubble a bit over 300 metres in diameter. Which is pretty impressive. But with nothing to support it, it will collapse as fast as it was created.
Basaltic rocks and granites melt at about 1200 C, and have a specific heat of roughly 1 kJ/kg/K. Assume about 200 degrees C at depth, so about 1MJ/kg to melt the rock. So our nuke delivers enough energy to melt 10^9 kg of rock. One million tons. Also impressive. But our 300 metre diameter bubble has a surface area of nearly 300,000 square metres, so we could only melt the walls to a depth of 3 metres, and we have double counted our energy.
Maybe we could suggest that we divide the energy into three - one third to blow the bubble, one third to melt the rock to a depth deep enough to build some sort of dome to hold the bubble open, and one third to cope with losses whilst the system stabilises (which we are simply assuming it will.) Then we still might blow a bubble of roughly 200 metres diameter.
Of course the assumption about the system “stabilising” as it cools is impossibly fanciful. There are so many ridiculous assumptions above, especially the bit about ignoring energy that goes into fracturing rock and the pressure wave, that the whole thing just imploding into a huge mess of molten and fractured rock with no useful hole is going to be where the smart money is. But looking at the energy yield from a big nuke in unconventional ways is sort of fun. Given two guys can carry a W80 weapon, with a 0.15 megaton yield, they are remarkably frightening devices.
I just want to point out that having posts from coremelt and Great Antibob to this particular topic should be candidates for the member-name/post content juxtaposition sweeps.
The easier way to achieve Pushkin’s aim would be to create a fissile mass of molten uranium and other metal. It will melt the rock below, and sink into the earth due to it’s own mass. Line the hole with casing as it goes down, and periodically toss in some more uranium and radioactive waste, and the job’s a good 'un.
Of course, it is a stinking radioactive hole but the multi-nuke option does that, too. And if you hit anything that blows out the bore (water, gas etc) you end up showering the landscape with radioactive fallout, but, well, progress.
In fact, this has been proposed as a disposal mechanism for high-level radioactive waste. Stick enough waste in a suitable container and let it get hot enough, and it could (slowly) melt through granite. Gravity does the rest. The real problem is the suitable container.
Damn right progress, you sir/madam have won a place on my team. Don’t worry about the landscape, it will be littered only with the corpses of the naysayers up thread.
It should also be noted that a nuclear weapon is an electronic device, made with wires and integrated circuits and whatnot, and highly dependent on precise timing in order to function effectively. At the temperatures that the device needs to operate in, I imagine that it would be rendered inoperable before it ever got there.
We actually have some good experience getting quite sophisticated electronics to work at very high depth’s and temperatures. What the borehole loggers can mange is astounding. The logging whilst drilling (LWD) systems have electronics packages that sit right behind the drill in the bottom hole assembly. I’m sure there are no off the self nukes capable of working here, but nukes are not all that sophisticated. After all we had them working with 40’s electronics technology. The only really special bit is the electronics needed to synchronise the explosives, which is a bit unusual. The electronics needs to be reasonably resilient anyway, it sits next to radioactive components for extended periods.
This is true to an extent. But our electronics are actually more fragile, in many respects, to those available in the 40s. It takes several months of engineering design to get some of those tools to work in a consistent way under the 400+ degree temperatures seen in some of the deeper wells.
Part of the problem is the complexity of the logging tools. If you want a pressure switch that sets off a bomb 2000 ft above sea level, no problem. If you want a sophisticated logging package that coordinates an array of complex sensors that works flawlessly in a well that’s being actively drilled and operating in less than ideal conditions, the problem is considerably harder, which is why we had nukes in the 40s but have only drilled 25000 ft deep in the Gulf of Mexico 60+ years later.
Also, under the conditions the OP is imagining, things would absolutely fail. We have very little experience at conditions twice the depth of our deepest boreholes. Temperatures would be beyond our current engineering expertise. Several of my friends spend months designing equipment that functions at a mere 20 degrees beyond the previous generation of borehole electronics, much less the conditions you’d expect 50000 ft or more below the surface.
Also remember, we’re under severe size limitations here. Not only do we have to add hardware that can work in the bottom of a borehole to a nuclear weapon (I seriously doubt anybody has any nuclear weapons that are designed to work under those conditions), we have to make sure that the nuke plus this extra hardware will still fit into a hole 9 inches in diameter. That size limitation is going to add to the difficulty of engineering a nuke that will work at the bottom of a borehole in 300-500 F temperatures.
Indeed. My point was that we only need 40’s level sophistication to set off a nuke. They don’t actually need anything fancy at all. It is mostly about precise timing of high voltage spikes - mostly to initiate the conventional explosives in a precise manner, and partly to hit the imploding core with neutrons. This could be done with vacuum state electronics then, and could still now. Getting the beast hot could cause all sorts of other problems I suspect. Enough that an off the shelf nuke would probably malfunction due to changes in physical properties or shape of its constituents.
As it pertains to this application, the above storage limit isn’t a relevant one. That’s the record for storing neutral antihydrogen, but for disintegrating unwanted material, all you need is a steady stream of antiprotons, which have been stored in storage rings for days at a time and could (in principle) be delivered to the target site via a long, thin, evacuated pipe. This ignores other obvious engineering issues, but storage time itself isn’t a problem.
I don’t think thats a problem if you can make the bomb pretty long. Most of the mass in this long bomb could be a passive cooling system. You only have to keep the bomb cool long enough to get it down the shaft (wonder how long that would take roughly). I think desiging a cooling system that could keep the bomb at around the boiling point of water would be pretty easy. Around the temp of melting ice is IMO doable too at first blush.
Can you guys please go digging, bombing, fracking, blasting, quaking and shaking another planet besides the one I am trying to stand upon and live in? Please. Thank you.
(I’m trying to make the point that we do not know enough about the planet to go trying such destructive technologies upon it - even if they were feasible. We are doing enough damage with just the technologies we have at hand now.
That being said: Scientific curiosity is not what is dangerous, it is lack of common sense in pursuit of a profit, that is most perilous to us all.
Your sense of scale is severely messed up. The earth is in no danger of being destroyed by anything we’re doing.
On the other hand, we could make it a severely uncomfortable place for human habitation, but that’s an entirely different matter. And also impossible given this type of test. And what it has to do with fracking or earthquakes, which are outside the purview of using nukes to create holes, I have no clue.
This Chicken Little scaremongering is almost as bad as the people claiming we shouldn’t power the LHC due to the off chance of creating earth-destroying black holes.
Unless you live in the Kola Peninsula (where the borehole is), it’s unlikely that anything anyone does to this borehole is going to affect you much. Putting a nuclear weapon down a borehole is not, Hollywood to the contrary, going to destroy the Earth. Even if we got all the way to the Earth’s core and exploded a nuclear weapon there, that wouldn’t destroy the Earth. A nuclear weapon hasn’t got nearly enough energy to do that. The world’s combined nuclear arsenal doesn’t have nearly enough energy to do that. Not even close.