Work out nuclear fission energy instantly with clear inputs, formula shown and shareable results.
Each uranium-235 fission releases about 200 MeV, and a gram contains 2.56e21 atoms, so fissioning one gram liberates 8.2e10 J - roughly a megawatt-day, or the energy of 3.4 tonnes of coal. That million-fold energy density over chemical fuels is the entire case for nuclear power.
Atoms in the sample
N = (mass / molar mass) x NA
Energy released
E = N x energy per fission
It is the average for uranium-235, split mostly between the kinetic energy of the fragments, with about 5% carried away by neutrinos and unavailable.
A 1 GW electrical plant at 33% efficiency fissions roughly 3 kg of uranium-235 a day, though the fuel loaded is far heavier because of enrichment levels.