Abstract: The invention concerns a nuclear power plant located in an underground cavity, with a small high-temperature reactor which, together with a heat exchanger apparatus, is housed in a steel reactor pressure vessel. The reactor core comprises spherical operating elements which pass through the reactor several times. In order to provide unimpaired access to the components of the primary loop from above, the loading installation of the small high-temperature reactor is designed in a specific manner. It comprises a section located in a loading space under the reactor pressure vessel including a discharge device and a conveyor device. An addition device for fresh operating elements and a collector vessel for used operating elements are arranged either outside the underground cavity or, in the alternative, in the loading space.

Abstract: A medium power, high temperature pebble bed nuclear reactor, which includes a means for introduction and withdrawal of operating elements. The installation is provided in such a way that it can be more economically built and operated. The installation includes several input stations above a prestressed concrete pressure vessel, and charging hatch blocks positioned on top of the prestressed concrete pressure vessel. The blocks include selectors through which the pebble-shaped operating elements, after traversing helical and meandering charging conduits, reach into the reactor core. The selectors and charging conduits are installed within armored ducts which penetrate the prestressed concrete pressure vessel. Similar armored ducts are provided for exit ducts for withdrawal of pebbles from the core, and a first common exit hatch block is connected to the exit ducts. The block is arranged within foundation walls which support the prestressed concrete pressure vessel.