Eli5: What exactly are the conditions that have to be met for a nuclear reaction to occur? Why does it have to involve Uranium 235 and similar isotopes? The world is made out of atoms. If we were to split the nuclei of the atoms of like a T shirt would it cause a nuclear reaction?
In: 6
Splitting a nuclei of an atom is a nuclear reaction. The problem is how to sustain it at a level that might prove useful. If an object is continuously bombarded by fast neutrons and collisions with nuclei cause the nuclei in that object to split, then yes, there will be a “nuclear reaction”. But it won’t be sustained or it will sustain itself about as long as a source of those neutrons are present. (let’s not discuss more complicated stuff for the ELI5)
The nature of radioactive material like U235 is that when it absorbs a neutron, the nuclei fairly quickly splits and releases two or three more fast neutrons. This is not true for most other nuclei – some simply absorb the neutron and remain fairly stable, others might split but not release 2-3 neutrons or have the release be of sufficient “speed”.
So, ELI5, 1 becomes 2 becomes 4 becomes 8. etc So this reaction sustains and builds on itself. If sufficient U-235 is present and in a dense enough configuration, then the reaction feeds back on itself and goes boom. But in a nuclear reactor, the number of reactions are controlled by design (use water or graphite to absorb excess neutrons) so that it doesn’t go out of control and remains at a steady state.
Bottom line the problem is not splitting the nuclei but sustaining that process.
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