出典:Wikipedia
出典:『Wikipedia』 (2010/10/22 00:03 UTC 版)
The critical size is the minimum size of a nuclear reactor core or nuclear weapon that can be made critical for a specific geometrical arrangement and material composition. The critical size must at least include enough fissionable material to reach critical mass. If the size of the fissionable material is less than a certain minimum, fission neutrons escape through its surface and the chain reaction is not sustained.