  The decay of instable nuclei is being used in a broad range of applications
from detector calibration to power sources. As the public acceptance of
classical fission nuclear technology is decaying and its integral costs are
enormous, alternative production routes are required. The mathematical
formalism and fundamental considerations are presented for the use of ion
accelerators for isotope production. A focus is put on the production of
nuclear power sources to substitute Pu-238 based batteries. 20 MeV protons are
found to produce {\alpha} emitting polonium isotopes from bismuth with an
energy efficiency of up to 0.031%. Some hours are required to produce a 1Wth
power source of the 2.9 year half-life {\alpha} emitter Po-208 with a suitable
accelerator. The accelerator approach offers more flexibility for tailoring of
nuclear products and less waste. The technical requirements are close to and
compatible with the planned International Fusion Materials Irradiation Facility
accelerator
