Remarks on the yield of fission bombs.

This article focuses on resolving the paradox that the total energy yield of a fission bomb explosion is independent of the energy ϵ released per fissioning nucleus. It revisits and derives the yield formula originally presented in the 1940 Frisch–Peierls Memorandum, showing that while a larger ϵ increases the rate of energy release, it also shortens the burn time of the chain reaction, resulting in fewer nuclei fissioned and thus a total yield unaffected by ϵ. The analysis employs neutron diffusion theory and models the bomb core's expansion as a homologous process dominated by radiation pressure, leading to a physically transparent explanation of why the total yield depends on core parameters but not on the energy per fission. This work clarifies historical and theoretical aspects of nuclear explosion physics relevant to researchers studying nuclear chain reactions and the Manhattan Project.