# Nuclear Warheads; select-a-yield? **URL:** \ **Category:** Factual Questions\ **Created:** [October 15, 2001, 4:25am UTC](https://boards.straightdope.com/t/nuclear-warheads-select-a-yield/87442 "2001-10-15T04:25:35Z")\ **Posts on this page:** 10\ **Page:** 2
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [January 2, 2016, 3:55pm UTC](https://boards.straightdope.com/t/nuclear-warheads-select-a-yield/87442/21 "2016-01-02T15:55:42Z")
And what’s the point of variable yield, anyway? The whole reason to use nukes is because you want a really big bang, and don’t care about the political implications of it. If you want something more precise that won’t hit your target’s neighbors, or if you don’t want the entire planet pissed off at you, use a MOAB or other, smaller, chemical explosive. ---
**Author:** ![billfish678](https://avatars.discourse-cdn.com/v4/letter/b/7bcc69/32.png) [@billfish678](https://boards.straightdope.com/u/billfish678)\ **Post date:** [January 2, 2016, 4:17pm UTC](https://boards.straightdope.com/t/nuclear-warheads-select-a-yield/87442/22 "2016-01-02T16:17:31Z")
> [@Chronos](#): > > And what’s the point of variable yield, anyway? The whole reason to use nukes is because you want a really big bang, and don’t care about the political implications of it. If you want something more precise that won’t hit your target’s neighbors, or if you don’t want the entire planet pissed off at you, use a MOAB or other, smaller, chemical explosive. Lets say you are hitting a run of the mill air field with run of the mill planes and buildings. A 100 kiloton is way plenty. You DON"T need A few megatons. All that is going to do is destroy stuff outside the target area. Why incinerate any more innocent people than you need to? ---
**Author:** ![Hail\_Ants](https://avatars.discourse-cdn.com/v4/letter/h/dc4da7/32.png) [@Hail\_Ants](https://boards.straightdope.com/u/Hail_Ants)\ **Post date:** [January 2, 2016, 10:00pm UTC](https://boards.straightdope.com/t/nuclear-warheads-select-a-yield/87442/23 "2016-01-02T22:00:20Z")
> [@Chronos](#): > > And what’s the point of variable yield, anyway? The whole reason to use nukes is because you want a really big bang, and don’t care about the political implications of it. If you want something more precise that won’t hit your target’s neighbors, or if you don’t want the entire planet pissed off at you, use a MOAB or other, smaller, chemical explosive. Gen-Xers like me grew up thinking that nuclear war would probably be all or nothing, so specific details like these seemed pointless. However from the US and USSR’s point of view (and even more for the smaller nuclear states) nuclear weapons were just another weapon in their massive arsenals. And for the first few decades of the Cold War, before MIRV-tipped ICBMs became the ultimate weapon, the possibility of a limited exchange was a very real one (and obviously, it would be _preferred_ to MAD). Therefore nuclear weapons were made as flexible as possible to make them as useful as possible for every conceivable scenario. If something were to happen dial-a-yield nukes could make an all out exchange \*less \*likely. ---
**Author:** ![Count\_Blucher](https://avatars.discourse-cdn.com/v4/letter/c/c5a1d2/32.png) [@Count\_Blucher](https://boards.straightdope.com/u/Count_Blucher)\ **Post date:** [January 2, 2016, 10:22pm UTC](https://boards.straightdope.com/t/nuclear-warheads-select-a-yield/87442/24 "2016-01-02T22:22:34Z")
… ---
**Author:** ![glowacks](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/glowacks/32/5548_2.png) [@glowacks](https://boards.straightdope.com/u/glowacks)\ **Post date:** [January 6, 2016, 5:27am UTC](https://boards.straightdope.com/t/nuclear-warheads-select-a-yield/87442/25 "2016-01-06T05:27:29Z")
> [@beowulff](#): > > Even though it’s a zombie, it’s nice that it was re-animated with a correct answer. > Tritium injection is the key. Since these warheads are “boosted fission,” they derive a large part of their yield from the additional fission of a U-238 tamper, caused by fast neutrons from D-T fusion in the “Pit.” If the amount of D-T is reduced to zero, the device becomes a pure fission weapon, resulting in a fraction of the possible yield. Adding on to this, Thermonuclear weapons get their vastly increased yield not through fusion directly, but through the ability of the fast neutrons that fusion generates to fission U-238, whereas the primary fissionable material of the first nuclear weapon used was highly enriched with U-235 that is much easier to fission, and we spent tons of money getting that uranium refined into the more fissionable isotope. With thermonuclear weapons, we can just pack more of the less-useful uranium into the weapon, and get large amounts of it to fission due to the large amounts of fast neutrons produced in the second stage of the weapon. The key to a large yield is to have a lot of reactions occur while the density of the material is still high enough, since as the reactions progress the device will blow itself apart. If you can start with a slightly better packed material, you have more room to expand before the reaction rate drops. Just make it not quite as compacted, and you get a smaller yield. ---
**Author:** ![bump](https://avatars.discourse-cdn.com/v4/letter/b/7c8e57/32.png) [@bump](https://boards.straightdope.com/u/bump)\ **Post date:** [January 6, 2016, 3:58pm UTC](https://boards.straightdope.com/t/nuclear-warheads-select-a-yield/87442/26 "2016-01-06T15:58:59Z")
> [@billfish678](#): > > Lets say you are hitting a run of the mill air field with run of the mill planes and buildings. A 100 kiloton is way plenty. You DON"T need A few megatons. All that is going to do is destroy stuff outside the target area. > > Why incinerate any more innocent people than you need to? Actually a 1 or 5 kiloton warhead would probably be more than adequate to wreck an entire airfield. A 100 kiloton weapon would be enough to seriously fuck up a good sized city. ---
**Author:** ![gnoitall](https://avatars.discourse-cdn.com/v4/letter/g/bb73d2/32.png) [@gnoitall](https://boards.straightdope.com/u/gnoitall)\ **Post date:** [January 6, 2016, 9:39pm UTC](https://boards.straightdope.com/t/nuclear-warheads-select-a-yield/87442/27 "2016-01-06T21:39:15Z")
> [@coremelt](#): > > This thread was started in 2001, at that time Wikipedia had barely been founded. Indeed. The cited Wiki article was initially created in 2006. That’s one of the the potential pitfalls of scolding a zombie. ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [January 6, 2016, 9:59pm UTC](https://boards.straightdope.com/t/nuclear-warheads-select-a-yield/87442/28 "2016-01-06T21:59:08Z")
An airfield is really easy to wreck. You ought to be able to do it with one planeload of conventional munitions. ---
**Author:** ![silenus](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/silenus/32/166_2.png) [@silenus](https://boards.straightdope.com/u/silenus)\ **Post date:** [January 6, 2016, 10:34pm UTC](https://boards.straightdope.com/t/nuclear-warheads-select-a-yield/87442/29 "2016-01-06T22:34:42Z")
Dial-A-Yield™ is also useful in a tactical setting to prevent your own forces from getting crisped. A 1 KT nuke could just disrupt an enemy attack, where a 1MT nuke would take out the entire area _including_ friendly forces. ---
**Author:** ![Tripler](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/tripler/32/21807_2.png) [@Tripler](https://boards.straightdope.com/u/Tripler)\ **Post date:** [January 7, 2016, 1:17am UTC](https://boards.straightdope.com/t/nuclear-warheads-select-a-yield/87442/30 "2016-01-07T01:17:51Z")
Dial-A-Yield™ is also useful for second and third strikes. See, nuclear weapons tend to throw up a lot of dust, dirt, and debris that follwing RVs must pass through as they zip towards the ground at Mach 8.OhMyGod, and that hovering dust/debris can actually act like a sandblaster to the warhead before it gets to a detonation point (‘Ooops, broken warhead!’). So it is entirely feasable to set your yields lower on two outside targets while you smack the middle one with the heaviest hammer you have perhaps an hour later or so. I would comment more, but \*\*minor7flat5’\*\*s link is a good book and goes into some very good detail that I’d prefer not to here. Tripler It was a good read–first book in _years_ that I finished in one week! [Previous page](https://boards.straightdope.com/t/nuclear-warheads-select-a-yield/87442.md?page=1)