The answer to the question is of course 1.
However there are very-very-very subtle effects one can do with ionic charge and chemical bonding. For instance, one type of beta-decay is called electron capture and it involves the nucleus capturing one of it's orbital electrons. Thus converting a proton to a neutron. So, if you play the chemistry game and use electron withdrawing ligands, you can modify the half-life. Usually you can change it by 1/1000th of it's original value, barely at all essentially but measurable.
If you were in the Mega Kelvin regime you won't have nuclear decay but nuclear reactions, as now there is enough energy available to fuse nuclei together.