Apparatuses and methods produce radioisotopes in multiple instrumentation tubes of operating commercial nuclear reactors. Irradiation targets may be inserted and removed from multiple instrumentation tubes during operation and converted to radioisotopes otherwise unavailable during operation of commercial nuclear reactors. Example apparatuses may continuously insert, remove, and store irradiation targets to be converted to useable radioisotopes or other desired materials at several different origin and termination points accessible outside an access barrier such as a containment building, drywell wall, or other access restriction preventing access to instrumentation tubes during operation of the nuclear plant. Example systems can simultaneously maintain irradiation targets in multiple instrumentation tubes for desired irradiation followed by harvesting.
 This invention was made with Government support under contract number DE-FC52-09NA29626, awarded by the U.S. Department of Energy. The Government has certain rights in the invention.