Chemistry / Unit 12 Chem 2541 short lesson, about 20 seconds
Chain Reaction as a Self-Sustaining Threshold
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The idea
A fission chain reaction becomes self-sustaining once neutrons produced per fission equal or exceed those absorbed plus lost.
In practice
Too little fissionable material lets neutrons escape before causing further fission, so the reaction dies out.
Where people slip
Assuming any amount of fissionable material sustains a chain reaction ignores that criticality is a threshold set by amount, geometry, and neutron loss.
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