In-core irradiation device for a nuclear reactor

In operation, the irradiation samples should have the coolant flowing directly around them and in spite of this, loading and unloading of the irradiation duct should be possible in full reactor operation. This is achieved by the irradiation duct surrounding the irradiation samples and having coolant flowing trough it being closed by a stopper which can be coupled to the irradiation capsule above the coolant inlet slots, as long as the duct is unoccupied. This stopper can be placed at the bottom of an irradiation capsule by suitable coupling and latching devices, and can be driven into the reactor core with this capsule. The invention can be used for producing isotopes, for example. (orig./HP)