The existing data on superallowed Fermi -decays, including some new data on the decay of proton-rich nuclei, are analysed incorporating (i) detailed calculations of the statistical rate function, f, (ii) "outer" radiative corrections to order Z23, and (iii) Coulomb corrections, c. The contribution to c arising from charge-dependent configuration mixing is estimated in a simple model, which relates c with Coulomb displacement energies of 0+ states in isotriplets and to off-diagonal Coulomb matrix elements. Estimates from the simple model are confirmed in more detailed shell-model computations. A second contribution to c arising from bindingenergy differences is calculated in a single-particle model using Saxon-Woods radial wave functions. The resulting effective coupling constant for nuclear -decay is found to be slightly lower than the previously accepted value, and the implications in Cabibbo theory are discussed. However the scatter in experimental ft values, though reduced, is not removed by these calculations, and some discrepancies, such as were recently observed for the mass-34 mirror decays, cannot be explained. 1973.
