Apparatus and methods of production of radioisotopes in nuclear instrumentation tube reactor

A method of producing radioisotopes, the method comprising; inserting at least one target (250) irradiation in a sleeve (260) of a subsystem tube, inserting the sleeve into a tube (50) instrumentation of a reactor (10) nuclear, extending the instrumentation tube in the reactor and having an opening (51) accessible from outside the reactor, to expose the target irradiation to neutron flux present in the nuclear reactor when operating, substantially become the target of irradiation in a radioisotope when exposed to a neutron flux present in the nuclear reactor, the sleeve having a substantially constant inner diameter, and the tube system further including at least one clip (266) shaped to engage with the sleeve and a variable inner surface of the instrumentation tube; and removing the irradiation target and produced radioisotope from the instrumentation tube.