Cumulative Fission Yield
The cumulative fission yield, is the number of atoms of a specific nuclide produced directly and via decay of precursors per 100 fission reactions. If the nuclide is stable, the cumulative yield is the total number of atoms of that nuclide remaining per fission after the decay of all precursors (ignoring the effects of other nuclear reactions e.g. nuclear capture). Similarly, for a nuclide with a much longer half-life than any of its precursors, the cumulative yield is very nearly equal to the amount produced at a time short compared to its half-life but long compared to the half-life of its precursors. However, for a radioactive nuclide for which this is not the case, some atoms will have decayed before all have been produced. In such a case, at no time will there actually be present the reported cumulative yield of atoms per fission present.