I think the title explains it, but I am interested in how a world might differ from our own if fission had no radioactivity associated with the fuel, process, or waste/byproducts. The obvious answers are more nuclear power and maybe more common use of nuclear weapons, but I'm looking for other unexpected outcomes or unexpected secondary effects of the outcomes I mentioned.

If you've gotten this far without your head exploding: I understand how this sounds ridiculous, as radioactivity is a natural consequence of fission reactions. Try to focus on the outcome here, instead of the mechanism. If you just can't help it and feel the need to school me on why this is a spectacularly dumb question, go for it. Just make sure I learn something about nuclear physics along the way.


closed as too broad by Mołot, M i ech, user535733, StephenG, JohnWDailey Dec 10 '18 at 2:29

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    $\begingroup$ At present the question is profoundly unclear. Please explain in a little bit more detail what is to be understood by "nuclear fission had no radioactivity associated with the process". More specifically, (1) how is the chain reaction supposed to work and (2) in what form is the energy supposed to be released. Ah, and by the way, "radioactivity" in general is not a scare word. We live in a radioactive world, we always did, and we are adapted to it. Uncontrolled radioactivity is dangerous, but so is uncontrolled heat or uncontrolled electric power. $\endgroup$ – AlexP Dec 9 '18 at 20:51
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    $\begingroup$ As usual, when you change basic physics you end up with universe totally unlike our own. You probably just made stars not work... $\endgroup$ – Mołot Dec 9 '18 at 21:00
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    $\begingroup$ Are you talking about nuclear fission not producing dangerously harmful radioactive waste? So basically a world where Hiroshima and Nagasaki can happen, but not Chernobyl and Fukushima creating uninhabitable zones of exclusion? $\endgroup$ – Andrew Grimm Dec 9 '18 at 23:41
  • $\begingroup$ no conservation of energy? $\endgroup$ – user6760 Dec 10 '18 at 0:29
  • $\begingroup$ I think that you want a world where nuclear processes are just like in our universe, but fission of uranium and plutonium does not produce dangerous radioactive waste, so nuclear powerplants aren't really dangerous and nukes doesn't contaminate the soil. Well... more or less, that's our universe. As of 2018 Hiroshima is a pretty city and the forests near Pripyat are a gorgeous natural park thriving with wildlife. Our fear of radioactivity stems from Cold War fears, Greenpeace propaganda and plain ignorance, with just some little drops of sensible truths. $\endgroup$ – Rekesoft Dec 10 '18 at 12:08

The short answer is that no radioactivity from fission means no energy released, and so no nuclear power or nuclear weapons. The radioactivity is how the energy is released — it may be emitted as neutrons, photons (gamma rays) or bits of the atom (alpha or beta radiation). Because nuclear reactions release much more energy than chemical reactions, the energy released is high enough to be damaging.

You could envisage a world where the typical energies of chemical and nuclear reactions are similar, and so the energy from nuclear fission is released as thermal energy (heat) instead of radioactivity, but in that case nuclear power and nuclear weapons will be no more powerful than coal power and conventional weapons.

  • $\begingroup$ ... And chemistry won't work reliably, and life is an application of chemistry. $\endgroup$ – AlexP Dec 9 '18 at 20:53
  • $\begingroup$ Heat partly fall under infrared radiation, so that become really funky at best. $\endgroup$ – Spoki0 Dec 9 '18 at 20:57
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    $\begingroup$ Is there any real reason that the waste products of nuclear fission need to be radioactive? That would mean that nuclear reactors are very dangerous while they're operating, but you wouldn't have any nuclear waste, which is the biggest problem with nuclear reactors. $\endgroup$ – Peter Shor Dec 9 '18 at 23:44
  • $\begingroup$ @PeterShor There is. The problem lies with the half-lives of radioactive isotopes created by fission products or with radioactives isotopes created by neutron capture (used to control the nuclear fission process, so called moderators). You could make them extremely short (less than a second) or long (more than 1 billion years) but in the case of Tritium (Hydrogen-3) or Carbon-14 but either split would make stars stop shining the way they do or fail to generate matter heavier than hydrogen or helium so we would not exist anyway. $\endgroup$ – GretchenV Dec 10 '18 at 9:10
  • $\begingroup$ @GretchenV: Carbon-14 is not generated in fission reactors, and tritium is nowhere near the most dangerous waste product of nuclear fission. We could deal with tritium. $\endgroup$ – Peter Shor Dec 10 '18 at 12:39

Sorry, but your world just can't exist in a way even remotely close to our world. Fission releases neutrons and photons, both are a types of radiation, to make it impossible, you have to remove neutrons and light from existence. Photons are carriers of electromagnetic interaction, neutrons are made of the same stuff that protons are: quarks. Quarks interact through electromagnetism and strong nuclear force, so removal of those two forces, removes both photons (light) and hadrons (class of particles to which protons and neutrons belong), leaving only gravity and weak nuclear force, so 2 out of 4 fundamental forces. In such world, atoms as we know them simply do not exist, world like that can not exist in way even remotely similar to our world.


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