The control rod regulates the power of the FRM II fuel element. There is, however, also the possibility of placing small samples into a dedicated space within the control rod in order to use the control rod as an irradiation position. It offers the highest possible neutron flux density of 2·1014 cm-2 s-1 at the FRM II, while reaching more or less the same flux density of fast neutrons (see table). It is only possible, however, to load and unload the position when the neutron source is shut down. Therefore, irradiation is only possible for a complete cycle of 60 days.