GAS-COOLING HIGH-TEMPERATURE NUCLEAR REACTOR

The invention relates to a gas cooled high temperature reactor located in the cavity of a pressure vessel, with spherical fuel elements, and removal apparatus for fuel elements. The latter is made of at least one ceramic pebble outlet tube extending through the graphite structural parts of the nuclear reactor (bottom reflector, bottom layers) and a number of metal pebble outlet tubes installed through the bottom of the pressure vessel. They are arranged coaxially in the liner of the passage through the vessel. To be able to dismantle the metal pebble outlet tubes, they are constructed of several releasably interconnected tube segments. Between the uppermost tube segment and the corresponding ceramic pebble outlet tube a compensating tube is provided and connected with the tube segment by means of a sliding joint. The other end of the compensating tube is fastened to the thermal bottom shield. Relative movements caused by the thermal expansion of the bottom shield and the pebble outlet tubes are compensated by the slide joints. Simultaneously, the necessary tight sealing is assured.