The current value of Vud is determined from superallowed beta-decay experiments. Other methods, briefly summarised here, have to overcome specific experimental hurdles before they are competitive. However, the nuclear results do depend on a nuclear-structure calculation of isospinsymmetry breaking, which is often a cause of some concern. We show here, by adopting the Conserved Vector Current (CVC) hypothesis, that these theoretical corrections can be tested for consistency. In this test, calculations based on the shell model with Saxon-Woods radial functions perform the best.
