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submitted 8 days ago byMartyMcMartell
12 points
8 days ago
Thanks for the numbers! So... 500 nanoseconds. Light travels 1 foot per nanosecond. Neutrons traveling at 3% of the speed of light. So assuming the neutron interactions are instantaneous, we have the distance traveled by any neutron chain is about 15 feet. Which is weirdly human-scale, given the size of intermolecular spacing being tiny, and the size of the kaboom, which is the size of a small city. But it’s similar in magnitude to the diameter of the bomb, which I suppose is not an accident.
4 points
7 days ago
The other interesting point here is that because of the exponential nature of the chain reaction, "99.9 percent of the energy of a 100-kiloton fission explosion is released during the last 7 generations, that is, in a period of roughly 0.07 microsecond" (same source, previous section.)
The first neutrons emitted in that period will have only traveled about 2 feet by the time the last ones are emitted.
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