Subnostr

Hrm, well. That one is fusion. Fission just requires heavy isotopes to split. They do so spontaneously all the time. It is why red glazed pottery shows up on a Geiger Counter. You can make even more unstable isotopes by adding a neutron. Neutrons don't have to overcome any repelling force to enter the nucleus.

You just have to increase the size of your sample till it's radius exceeds the mean free path of a neutron by a sufficient amount to cause a chain reaction.

The hard parts are refining enough material and assembling a critical mass fast enough that it doesn't just fizzle instead of bang.

ᴛʜᴇ ᴅᴇᴀᴛʜ ᴏꜰ ᴍʟᴇᴋᴜ 6mo ago

no, fission is caused by the *decay* of unstable isotopes throwing fragments of their nuclei at other nuclei, and HITTING them square on so they trigger a second round, and so on and so forth. has to happen literally millions of times to work as a "bomb"

if that reaction fails to reach sufficient precision of chained collisions, all you are going to get is some rapidly vaporising plutonium/uranium, because the heat release will drive apart the metal. then your target distance just went from a sniper shot at 10km to hit a tennis ball, to a sniper shot from pluto trying to hit a human head.

i don't think you really have actually thought it through because you didn't have any reason to distrust your physics and chemistry teachers in highschool.

fission is simple enough to understand. decay blasts out alpha/beta particles that hit other protons, and this emits heat.

however, the reality is that the heat is the overwhelming content of what is released when a nucleus is broken and the electrons stop holding all those photons inside between them and the nucleus

these photons are repulsive to electrons and with sufficient of them, will break the metallic conductive grid that normally serves to conduct infrared photons and electrons (mainly), and turn the metal into a gas, and when it's a gas, it's thousands if not millions times greater distances between the hypothetical fissioning nuclei and then they still have to hit others to continue this, or otherwise, you know, they just break something far away.

anyway, i can see the picture inside my head about how utterly tenuous the supposed analogy between fission reactions and combustion: spoiler alert: they are entirely different processes, one is molecular, the other requires fragments or whole nuclei to separate from the electron shell (which requires tremendous heat) and then it has to breach the shell of another atom's electrons, and it MUST hit the other nucleus square on or it will just zip past and end up hitting the wall or the ground or flying into space.

combustion, on the other hand, requires a reaction that occurs on the SURFACE of the electron shell between an oxidiser and causes a MOLECULE to undergo "molecular fission" and the difference between a bunch of diesel, which contains like 50 atoms of carbon and hydrogen, or so, at sufficient temperature that it's on the triple point, coming into contact with the oxygen, which is already optimised by your combustion regulation system, valves, cams, timing belts etc, making this go bang, is comparatively easy.

the only wildcard in combustion is access to oxygen, and the heat/and/or/pressure that along with the ratio gives you a bang. this tolerance for excess oxygen or excess combustible reduces the more you increase the heat.

*IN CONTRAST TO* where the solid, cool metallic plutonium must remain in solid form long enough meanwhile all those busted nuclei are blasting out heat so fast... into the rest of the unreacted plutonium, which is going to inherently be extremely volatile and i just can't see how even the most fancy shape charges system or especially not the old gun-style impactor method are going to succeed in getting more than maybe 2-5% of the payload to actually undergo fission before the whole thing is just a dirty bomb.

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Daniel Wigton 6mo ago

No. That is not how it works.

The decay of unstable isotopes does result in smaller atoms but the chain reaction doesn't come from those fragments hitting other nuclei. It comes from free neutron that are emitted and absorbed by other nuclei making them unstable (more unstable)

Uranium-235 has a half-life of 703.8 million years. If you add a neutron you get Uranium-236 with a half-life of 23.4 million years, but the neutron also carries enough energy into the nucleus via its momentum to provide the excitation energy needed to split the nucleus in the majority of cases. This releases more neutrons and it continues.

It is important to note that I didn't learn any of this from highschool chemistry or physics teachers, I learned it from David Macaulay's "The Way Things Work" colloquially known as "the mammoth book" the definitive source of technical information for the child and child-like everywhere.

Daniel Wigton 6mo ago

Ok, I may have also studied, chemistry, physics, and quantum mechanics as part of my Engineering Science degree as well. But it's been a while so claiming expertise based on it is a stretch.

ᴛʜᴇ ᴅᴇᴀᴛʜ ᴏꜰ ᴍʟᴇᴋᴜ 6mo ago

credentials are for losers. i know enough to be dangerous, and am always learning more to become more dangerous.

Daniel Wigton 6mo ago

I'll not argue that point. As I said, it doesn't mean much. It was long ago and just because I studied a thing doesn't mean I understood it or retained it.

There is also the issue that studying a thing doesn't make it true. This is currently a crisis in the humanities.

ᴛʜᴇ ᴅᴇᴀᴛʜ ᴏꜰ ᴍʟᴇᴋᴜ 6mo ago

Mises commented on this problem of the "soft" sciences being so pliable to political manipulation and lack of verifiability in his treatise Human Action.

that's the thing. there has been many things i read about years ago that i learned since were completely flawed from their premises. there is just such a party of circumstantial evidence against the idea that there is in fact such a thing as a plutonium explosive mechanism that i'm gonna just do this thing and consider the simple thermodynamics and kinetics to point out those points are extremely flimsy, before you even count the fact that apparently the team at Los Alamos got their bomb to work first time around, without even doing integration tests (and hardly any unit tests)

ᴛʜᴇ ᴅᴇᴀᴛʜ ᴏꜰ ᴍʟᴇᴋᴜ 6mo ago

i don't think nuclear fission is that orderly. sometimes a proton strikes and knocks out another, and doesn't also join. sometimes it breaks off several protons and releases the neutrons, and disrupts the electron configuration due to the change in the nucleus(i) now existing after the break.

in the slow, typical case, yes, it tends to be one proton bumps out one or two protons from the other, and you don't get an inordinate amount of heat.

with stuff like uranium and plutonium and americium etc they have such giant amounts of protons and neutrons in the middle of them that it feasibly could happen that a whole hydrogen atom worth of nucleus gets thrown out, or even bigger sometimes.

assuming that the whole objective of the refinement of decayed uranium to extract the plutonium is because it has a greater tendency to break apart more vigorously, i can say that probably there is a lot of other things that break, but obviously i think the point is that it's more likely to completely shatter (as in, release a lot of hydrogen nuclei, effectively). but that doesn't comport well with the "one proton in two protons out" story that we know is pretty accurate for uranium fission and is quite safe if you don't push it hard and cool it even harder.

idk what to say. the only way i can conceive of an actual explosive effect comnig from shattering nuclei is pretty simple: they turn into hydrogen, and then once the pressure and heat overcomes the containment, it rapidly detonates as a plain old hydrogen explosion.

in my opinion that is the best case scenario. the reality is not quite so clean as that.

the real world decay process of uranium produces huge amounts of iodine 131 and cesium 137. this is a sign that there is a progressive decay process, and when the newly formed structures scoop up their electrons, their boiling point is exceeded and off they go into the atmosphere. iodine is an easy one to see that happening, it just sublimes easily at about ... i forget, 90'C or so

cesium is a much smaller fragment, so already i know that uranium which is like 235 or something, and cesium 137 and iodine 131, we have here what clearly sounds like ... let's see, this can't come out of one uranium, as it would be 268

so this already suggests that even the relatively "calm" fission of uranium breaks off random amount of protons/neutrons from a uranium nucleus in the standard meltdown conditions. i also know a lot of hydrogen forms in the process, this makes sense, this is what you would expect from one proton being bumped out.

anyway, what's my point, oh yes, i was going through the question about how plutonium might hypothetically work if you can contain its heat long enough to keep it solid or at least supercritical while all those protons bash each other up, the ideal result would be hydrogen, which with the heat and then sudden exposure to oxygen would essentially make a fancy hydrogen fire bomb. you can make one of these anyway. just a cylinder of hydrogen, armor the hell out of it and put a magnesium charge in the middle of it. it won't be that much more fancy than a normal carbon based exploder but it will be a lot more impulse and shorter burst, a "pop" instead of a "boom". however both release about equal amounts of heat per mass of reagent in total so likely they also make nasty firestorms.

but either way. i just don't think that plutonium actually makes that much hydrogen that quickly, and even if it did, reliably, a lot of the plutonium is going to be boiled in the process, which is not going to explode because it's too dispersed for those protons to hit them.

the more you think about it, the more obvious it becomes that the last thing that is going to happen with a plutonium meltdown is an orderly production of primarily hydrogen, along with a huge amount of various kinds of radiation particles, heat, and whatnot.

more likely it's going to just boil. as i see it, that's the central reason why it's a hoax, the thermodynamics of the release of all that latent heat can't possibly allow the metal to stay solid, even under the most ideal conditions of implosion (ie, explosions all around it).