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Scenario: Last line of defense. I want to prevent anyone from reaching a highly guarded building.

Such building is in the middle of top secret, heavily guarded military area (think of Area 51). I want to make sure, that if my military base gets attacked, I have a way to protect my utmost secret hidden in such building.

Can I deploy nuclear bombs around it and make directional nuke-blast facing away the building?

I want to destroy everything else than such building - I want to be able to recover my super secret stuff from such building after everyone is killed.

Also, if such attack happens, I want to make sure such defense "works against everyone". What are my possibilities? Please stay inside current technology level.

BTW, money is not an issue

Also, this secret is "stolen from my enemies". So I have to assume such military base will be attacked amongst first

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    $\begingroup$ Are you saying if the buildings are unscrathed anything goes? then try neutron bomb for size deal minimum dmg to infrastructure maximum piecing dmg to anything that can eat and shit lol. $\endgroup$ – user6760 Apr 28 '15 at 12:09
  • $\begingroup$ Building must stay intact. Or better put: I have to be able to collect a secret stuff being stored in such building $\endgroup$ – Pavel Janicek Apr 28 '15 at 12:12
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    $\begingroup$ Why nuke something which you will probably regret later? alternative are aplenty such as begging, throwing tandrum, blackmail the guards with indecent photos of them with a housefly, seduce the general's daughter with 1 single push up using your d*** (should conserve energy for the infiltration later on) or request Snowden for a 1 to 1 coaching, etc. $\endgroup$ – user6760 Apr 28 '15 at 12:29
  • $\begingroup$ How do they even find the building that you keep your secret in? $\endgroup$ – Necessity Apr 29 '15 at 1:44
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    $\begingroup$ I tried this once in Rise of Nations to "save" a city under siege. The implications are rather obvious - it only really works once, and then you've destroyed most of your defences. Remember, whoever the attacker is, he can have multiple assault waves. If your ultimate defense weapon is a "defensive" nuke, it will only blast the current assault wave, while destroying all of your defences. That said, directional nukes do exist - for example, in thermonuclear bombs. But there is no directional explosive that doesn't leak at least some of the energy out as well - not great with nukes. $\endgroup$ – Luaan Apr 29 '15 at 8:42
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So the simplest way to make this work is to use an underground bunker instead of a building. Many feet of dirt/rock/concrete acts as a barrier to your weapon.

A nuclear weapon puts out extraordinary amounts of heat, and some radiation - the heat creates an overpressure wave in the air, which rapidly expands. This pressure wave is what does most of the damage.

Close to the center of the explosion, the high temperature is a serious issue. So to direct these forces would require some sort of structure that can redirect a massive overpressure wave, and will not melt when exposed to tremendous heat. You could probably achieve this with a large, rounded concrete bunker - it would redirect the pressure wave like a kind of echo.

Rather than ringing your building with a bunch of these 're-direction bunkers' and nuclear weapons, you could simply bury your building, and use the earth as one large shield. If you can get your nuke airborne for an air-burst detonation, you can increase the damage and minimize local fallout - the overpressure wave is distributed over a larger area, and the gamma/neutron radiation is absorbed by the air, instead of activating elements present in the dirt. You'll still have fallout from incomplete fission, but that comes with the territory.

That said, there are probably easier ways to defend a structure that is vital to your super secret facility. I'd recommend having an airfield nearby or on-site, and requiring a couple weaponized drones to be airborne and a couple more to be flight ready at all times. We live in the era of precision strikes after all - get with the times!

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  • $\begingroup$ There are allot of better more precise methods. Overkill is not beneficial. You also only have to do defensive/offensive measures if there is a tracking device on the package that cannot be blocked(which is unlikely). $\endgroup$ – Necessity Apr 29 '15 at 1:43
  • $\begingroup$ Quoting: "So I have to assume such military base will be attacked amongst first". Basically he is telling us that the base WILL be attacked and that in that case the enemy WILL know that the base would be underground... Which would eventually lead to an underground assault! $\endgroup$ – Noldor130884 Apr 29 '15 at 6:59
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The idea behind directional blasts is that they force energy from an explosion to rebound and head in a certain direction. This is probably not that feasible with a nuclear bomb(though I have no idea if its been done).

The problem is that the premise itself has several feasibility issues to overcome, which suggests nuclear force may not be the best option. The radiation that would be made by the bombs would stop anyone from being able to go near the place, you wouldn't be able to recover it. Use something that isn't nuclear.

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  • $\begingroup$ Don't understand why this is a comment on my answer. Note that my answer was before codemonkey's, so I obviously wasn't commenting on his answer. Neither my answer or the question mentioned underground anything. Also, no, nobody has to mention a piece metal. $\endgroup$ – Necessity Apr 29 '15 at 1:29
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In a vacuum, most of the energy from a nuclear blast is released in the X-ray spectrum (call it 95%). There are materials that can "reflect" X-rays by absorbing and re-emitting them, but they get heated up and ablate in the process. For example, the Ullam-Teller hydrogen bomb design uses a shell of heavy metal (depleted uranium, usually) to reflect the X-rays from the primary section to the secondary.

However, such a reflector only reflects a small fraction of the energy before it evaporates. You could try and build it thick enough, but then you run into problems like radiation pressure pushing the reflector away, so the blast is not directional as much as somewhat more intense in one direction.

Finally, all of the above holds only in vacuum; the moment you detonate a nuclear bomb within an atmosphere, you can manage to divert some fraction of the original x-rays, but those immediatelly slam into air molecules and heat them up, causing a fireball and a shockwave, neither of which can be convinced to only go in a certain direction.

TL;DR: You can redirect some of the initial radiation, but the shockwave and fireball will be omnidirectional regardless.

EDIT: @VilleNiemi brought a Project Rho link to my attention, which specifies that Orion drive designs were able to deflect as much as 88.5% of energy of an atomic blast into a 22.5° cone. But again, this blast will then immediately slam into the atmosphere and cause a shockwave going out in all directions.

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  • $\begingroup$ If memory serves, the Project Orion bombs were designed to be about 85% directional (in vacuum), but I can't seem to find the source off-hand. $\endgroup$ – Nathan Tuggy Apr 28 '15 at 17:44
  • $\begingroup$ Yes, and the US is even rumored to have repurposed the technology for bunker busting. But Mike L is unfortunately (for the question) right about this being much less "clean" in atmosphere. Still practical, but only if you don't need to worry about collateral damage from shockwave and fireball. You might as well build an underground bunker. projectrho.com/public_html/rocket/… $\endgroup$ – Ville Niemi Apr 28 '15 at 19:29
  • $\begingroup$ Here's the Atomic Rocket's link you wanted / needed: projectrho.com/public_html/rocket/…. Bear in mind that being able to direct 80-85% of the energy is awesome but that means everything around it must absorb 15-20% of a nearby nuclear detonation. The neutrons and blast won't be focused. $\endgroup$ – Jim2B Apr 29 '15 at 3:02
  • $\begingroup$ Also, they could get a much smaller cone with longer range by using light materials rather than tungsten (5.7 degree half-angle cone). But this is a weapon not a propellant. $\endgroup$ – Jim2B Apr 29 '15 at 3:04
  • $\begingroup$ @Jim2B Isn't that the same link I added in? The smaller cone thing only really pertains to the plasma wavefront, there's not much you can do about the X-rays and secondary effects. The neutrons are also a secondary effect; they come from high-energy X-rays blasting nuclei apart. $\endgroup$ – Mike L. Apr 29 '15 at 7:39
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It would be more realistic to lob nuclear weapons within a range close enough to the base to destroy anything outside but not doing irreversible damage within. You could calculate it to a T, ensuring that the temperature is too high for anything outside to survive while the base itself remains intact. The base would have to be shielded from the blast (dome shape?) with minimal radiation protection.

The one thing it couldn't handle would be say tanks right outside the base, which may get jostled around but may not necessarily kill anyone within. If the base is constructed well enough, you could just about have one land on top without damaging the base underneath and yet destroying everything above ground. It entirely depends on how well it is fortified.

Consider that in such extremes, the base would likely be equipped with hazmat suits to leave the compound afterwards, and of course there would have to be a way of getting the bomb to its destination, meaning there may be a weak point in the design for those who know about it.

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There's almost no way to build a nuclear weapon that will destroy things but not your secret safe thing, unless said secret safe thing is very deep underground.

Might I recommend simply building an upturned bowl of tungsten or other high-temperature material like ceramics and putting a huge pile of thermite on it? Tucked away beneath six inches (or more!) of molten iron slag(+ dome + insulation+ cooling maybe), whatever it is will be inaccessible until the slag cools or can be cooled and moved. Either way that'll take ages(explody cooling iron bits, adding water to hot thermite causes steam explosions and regular explosions), and from the language in the question it sounds like you have a way to reclaim control over the site.

(words of warning: You will almost certainly need to cut your thermite mixture with something else. In a vacuum the thermite mixture approaches 9000C, about 3x the melting point of tungsten and 2x the best hafnium carbide ceramics. Perhaps extra raw iron there simply as thermal ballast? Unoxidized iron would provide bonus 'smoulder' heat very slowly.)

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You could check section 5.2 of Fourth Generation Nuclear Weapons: Military effectiveness and collateral effects. But by and large I agree with Adam -- if your story has nuclear weapons in it, there should be plenty of collateral damage.

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Use Kinetic Energy Weapons [KEW]. You would put these in low Earth orbit (you did say money was no object) and drop them on the people outside your base. You could get blasts in the 20-50 kiloton range that would take out anything they hit.

The US Air Force did a report on a system called "Hypervelocity rod bundles" nicknamed "Rods from God" that used 20 foot long tungsten rods that dropped from orbit at Mach 10. With 6-8 satellites, you could hit any target within 12-15 from go code. It would hard to detect the launch and hard to intercept. At current Earth level tech, it would be a Billion dollar+ project.

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You do not want nuclear blasts, but radiation. If your attackers are living, use a massive dose of radiation: that would kill them. The same amount would fry anything that is electronic-based. You could fill the air outside and inside your base with radioactive vapors, and only protect the electronic equipment inside your base with a shield thick enough and emergency procedures. After the enemy has been dealt with, even if you loose, the place would be so life-threatening that there would be no chance to enter the building (see Chernobyl) for ages.

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