• ladicius@lemmy.world
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    1 month ago

    Would splitting one single atom in a non dense environment start a nuclear chain reaction? And why do I ask such questions when it’s simply a cartoon to snicker about?

    • Photonic@lemmy.world
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      1 month ago

      A nuclear reaction can only be sustained through very specific molecules that have the ability to undergo fission and release neutrons while they do. Those released neutrons then need to interact with new fissile molecules that surround the first one.

      The chain reaction also requires that there are enough of those molecules and that they are packed closely enough together, so the reaction doesn’t fizzle (no pun intended) out.

      That only happens in an environment like enriched uranium, which is uranium with an artificially high percentage of U-235 that doesn’t occur naturally –at least not anymore.

    • alpine_jim@piefed.social
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      1 month ago

      no, there are lots of atoms splitting inside your body every second.

      a single U-235 atom’s fission, releasing ~200MeV, (~30 picojoules), in ideal circumstances could maybe nudge a very small fine grain of sand (~ micrograms) enough to see movement (small fraction of a millimetre) under a microscope .

      It takes months of refining to make nuclear fuel that’s suitable for sustaining a chain reaction.

      it’s an interesting question, I’m glad I did the research checking that the orders of magnitude match!

      • Photonic@lemmy.world
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        1 month ago

        There are no atoms splitting inside the body. Nuclear decay happens, but not nuclear fission.

          • Photonic@lemmy.world
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            1 month ago

            I understand your confusion, since particles are ejected from the nucleus in both processes. Alpha decay may be a bit of a grey zone, since it expels a helium nucleus, so the atom is split into two very asymmetric parts, but it is generally not considered a fission process. Alpha decay and spontaneous fission are actually competing processes.

            Beta decay is something else entirely where no protons or neutrons leave the core, so there is no fission to speak of.

            And spontaneous fission is possible, but it’s extremely rare. For your example of Uranium, which is overwhelmingly (99.3%) U-238:

            Spontaneous fission is extraordinarily rare on a per-atom basis. Uranium-238, the most common uranium isotope on Earth, has a spontaneous fission half-life of about 8.4 × 10¹⁵ years.

            Source

            So with the uranium in your example there is a non-zero chance of spontaneous fission occurring, but it’s very unlikely.

    • AeronMelon@lemmy.world
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      1 month ago

      Was that not Albert Einstein’s fear regarding the bomb? That Earth’s atmosphere would simply ignite when exposed to the initial reaction?

      I think our sitting here, snickering at a comic about a biblical nuclear explosion, is proof that it wouldn’t happen.