Wonder if there is something akin to the opposite of a neutron bomb - a weapon that is designed to emit as little radiation as possible and achieve destruction through explosive effects alone but leave the post-blast area as radiation-free as possible. Is there such a thing, or could there be such a thing, invented?
It probably would be impossible for it to be totally radiation-free, but basically, small and radiation-free to the extent that people might not even realize it was a nuke, but rather, think it was a super-big conventional bomb.
Not possible.
The “cleanest” nuclear bombs are thermonuclear, and create most of their blast by fusion, which results in less radioactive particles. But, that’s “less” only when compared to a fission bomb.
Since fusion bombs are primed with a fission bomb, there is still plenty of contamination.
And, even if it was possible to detonate a fusion bomb without using a fission primer, fusion generates vast amounts of neutrons, which are going to make any area they reach radioactive.
Radiation is the nuclear bomb. This is like asking for a shrapnel grenade without all the little sharp flying bits or a shotgun without all the little metal balls.
However, there was once a joke about a nuclear bomb designed to destroy buildings without killing people where the punchline was “wastes great, less killing”, back when neutron bombs were in discussion and the Miller Light commercials were airing.
Project Plowshare was an attempt to use nuclear weapons for construction purposes. At first that sentence sounds like it might be some kind of weird joke about pro-nuke people going too far, but they really did want to use nukes for large scale excavation. Not to be outdone, when the Soviets found out about Project Plowshare, they tried to do the same thing themselves.
Project Plowshare claimed a 100-fold reduction in radiation release. Still, the radiation released was nowhere near zero and eventually even the folks in charge realized that the idea of using nukes for excavation was never going to work with the American public. Then again, they didn’t come to this rather obvious conclusion until after they had exploded a couple of dozen nukes in various tests.
Wikipedia article on Project Plowshare:
Wikipedia article on the Soviet counterpart, which exploded over 100 nukes:
The OP asked not so much for a radiation free nuke as one that has the lowest possible residual radiation after the blast. That probably is the inverse of a neutron bomb - try to get the maximum amount of energy into gamma rays and leave as little in the neutron flux as possible. But simply exploding the bomb at a high enough altitude not to kick up a massive plume of irradiated dirt would help as well. Given that the nuke intrinsically works by creating lots of neutrons, there is never going to be a neutron free nuke. But just as there are design choices that can maximise neutron radiation, one would assume that there are design choices that can drop it closer to some theoretical minimum.
The other problem is that a nuke is very inefficient and intrinsically leaves behind a large fraction of the original fissile material, and lots of reasonably evil products of that material. All of it radioactive, with wildly varying half lives and corresponding radioactive activity. Nothing can be done about that, although there may be design choices that can be made to reduce some components. Maybe things like (very expensive) use of precise isotopes of metals used in the bomb’s construction might help.
Would a matter-antimatter reaction be what the OP is looking for? Not that anything weaponizable is available today, but according to this reference on PET, the products of an electron-positron annihilation are 2 511-keV photons. Or gamma rays. No neutrons. Of course, getting a sufficient amount of antimatter, and keeping it contained…
It would not surprise me at all if the answer to what the OP’s looking for was discovered during research into nuclear pulse propulsion or directed-energy nuclear explosions. Something like what things such as Casaba Howitzer were supposed to provide. From that blog post, it looks like the device designers tried to optimize radiation output in the X-ray band.
Maybe you could make a device with fusion fuel that relied on an aneutronic fusion reaction? Something that existing thermonuclear weapons explicitly do not do. Now how you get a weaponizable quantity of, e.g., protons and Boron 11, to fuse without something like a fission bomb to drive the reaction, is yet another engineering exercise.
We can’t know, because OP’s question is insufficiently precise.
The lack of precision is caused by a lack of understanding, and the resulting oversimplified view that “radiation” is just one thing.
Your hypothetical matter/antimatter weapon would be low-residual but perhaps the most “radioactive” kind in terms of pure photonic output. You’d get no fallout from incomplete fission and hot fission products, and no neutron activation, but that burst of pure gamma is the very definition of radiation.
The OP doesn’t ask for the lowest amount of neutrons, he asks for the lowest amount of radiation. That’s why the whole question is not even wrong. Photons are radiation. A nuclear explosion that releases very little radiation is a very little nuclear explosion.
What about 1-kiloton suitcase nukes, would the explosion be passable as a giant MOAB? (Let’s say, at sea, where people wouldn’t care so much about fallout)
What **beowulff **said. The quote from the OP about what he’s looking for is:
As we know, the explosive effects from a nuclear weapon come from radiation absorption on the immediate surroundings, primarily atmosphere and, if near the ground, a bunch of dirt. All of which then expands very violently and causes still other things to break down range.
He just wants something that doesn’t leave any residual radiation behind afterwards. As that primarily comes from neutron absorption of the surroundings, no neutrons should equal not much residual radiation, right?
If the question is to not have the explosion identifiable as “nuclear,” would a gigantic gamma pulse leave a physical signature in the surrounding area?
If the nuclear weapon archive is correct, very small detonations (and IIRC, 1kt is pretty large for things like a SADM), are very inefficient in utilizing their material. IOW, there’s going to be a lot of bomb material in the general vicinity.
Further, and this may be counter-intuitive, for small devices (1kt and smaller) the radius of significant prompt ionizing radiation may extend quite a bit further than either radius for significant blast or thermal effects. Prompt ionizing radiation doesn’t scale in atmosphere as well as thermal radiation or blast effects.
Of the top of my head, this is pretty significant for devices below 1 kt, and I don’t whether most of the harm is due to gamma or neutron exposure. E.g., during Crossroads, goats were tethered inside a battleship gun turret (Nevada or Utah, IIRC), behind about a foot or so of armor plate. The blast didn’t get them, but the 20-40 Sv of neutron radiation did.
So, your blast is going to have quite a nearby few people with some burns, who might end up dying two weeks later from Stage 2 radiation sickness.
EDIT: Oh, and posters like Stranger probably can help more with this, but IIRC, nuclear dets had a characteristic double-flash. (caused by the initial burst of radiation leaving the device, just before the atmosphere ionizes around the device and is opaque for anywhere between a millisecond and a few seconds. After the opacity dissipates, the second flash is visible.). I thought this was pretty characteristic of nuclear detonations, and wasn’t a feature of even large conventional detonations like Minor Scale, but I don’t know.
So there’s another difference between the suitcase/large duffel bag nuke and the MOAB.
A couple of points about antimatter: First, you get nothing but photons from reacting electrons with positrons, but this is not the case for reacting protons and antiprotons with neutrons and antineutrons. There, you’ll start out by making a bunch of pions, which will fly out and hit things, then eventually decay to either gamma rays (for neutral pions) or muons and neutrinos (for charged ones), then the muons will eventually decay to electrons or positrons and more neutrinos, and finally any positrons that are produced will eventually find electrons to pair up with. The net result is that a lot of energy gets wasted in neutrinos, and what isn’t neutrinos will eventually turn into photons, but not until it knocks around a good bit as other sorts of particles.
Second, even photons can transmute materials, if they’re high enough energy. One doesn’t usually encounter photons of sufficient energy, but then, one doesn’t usually deal with antimatter.
My understanding is that most H-bombs not only have a 1st-stage fission bomb to ignite them, but that most of the energy is created not by the 2nd-stage fusion explosion itself, but by a 3rd-stage of fission (e.g. of depleted uranium) ignited by the fusion. Bombs in which most of the energy comes from fusion have been designed, but apparently never built.
Disclaimer: I don’t really know what I’m talking about. If I did, they might have to kill me. :o
The wiki on nuclear weapons is pretty extensive. Practical pure fusion weapons may be possible, but we don’t know how to make them yet. (The article mentions a theoretical impractical design of a 3 ton bomb with the yield of 3 tons of TNT.)
