Abstract: Exemplary embodiments of the present invention are directed to the placement of one or more isotope production rods in a fuel bundle. The placement may be based on any one of, or a combination of, numerous factors such as relative location of core-monitoring equipment, the type of radioactive isotope being produced, the half-life or length of decay of the radioactive isotope, the neutron absorption rate of the target isotope to produce the radioactive isotope, the desired specific activity of the radioactive isotope being produced, the amount of neutron flux in different areas of the fuel bundle, the duration that the target isotope/radioactive isotope is expected to remain in the reactor until removed (i.e., harvested), etc.