Abstract: A process is provided for the long term shutdown of a high temperature nuclear reactor comprised of a pile of spherical fuel elements in a core by means of a neutron absorbing absorber material wherein the absorber material consisting of spherical absorber elements is introduced in the core of spherical fuel elements in the form of a column, but wherein the intermixing of the absorber material with the fuel elements is prevented. An apparatus for practicing the process is also provided comprised of a graphite side reflector concentrically surrounding a circular cylindrical core filled with a pile of spherical fuel elements of a high temperature nuclear reactor, into which at least two nose shaped projections distributed uniformly about the circumference radially project, with each of the projections comprising a vertical cavity to contain the absorber material. The vertical cavity is located in the vicinity of the core in the area of the frontal side facing the core of each projection.

Abstract: A shutdown system for a high temperature nuclear reactor where absorber material elements in the form of balls pass from an elevated reservoir into a vertical channel formed by aligned vertical cavities in horizontal, nose-shaped projections from the side reflector. The balls are transported back to the reservoir by way of a conveyor device. It must be insured that even in the case of accidents the absorber balls arrive in the cavities and that a rapid return of the absorber balls into the reservoir takes place. For the purpose, the reservoir is provided with an automatically-actuated and controllable device for releasing an opening between the reservoir and the vertical channel feed line. Below the channel is a removal tube terminating in a housing and arranged to form a pile of the absorber balls which seals the removal tube. To return the absorber balls, a metering gas acts on the pile and brings the absorber balls to a carrier gas.

Abstract: A nuclear reactor installation with a simple configuration includes a transport container which may be placed on the cover of the cavity. The transport container bottom overlaps the cover access opening. A vertical displaceable pebble conveyor line extends from the pebble pile surface to the transport container interior. A blower is located between the transport container and the reactor. The blower suction line is connected to the transport container interior and the blower pressure line leads into the reactor vessel.

Abstract: In a nuclear reactor installation with a small high temperature reactor (26) all of the components of the primary loop, together with the control and shutdown installations (82, 92, 114, 116; 194, 198, 200) are located inside a steel pressure vessel (16) and may be installed and dismantled from above. This makes an economical subterranean construction possible.

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.

Abstract: An inspection device for the inspection of internal spaces in nuclear reactor installations requires extremely small dimensions while being capable of use at high temperatures and exposures to radiation during shutdown periods of the reactor. The device is designed so that it is readily adapted to a particular inspection purpose. The particular device meeting these requirements comprises a camera arranged in a tube and cooled in such tube. The objective of the camera and/or a mirror are each connected with means for relative movement. A source light and the movement means are designed as separate structural elements which may be assembled in different combinations in a modular fashion.

Abstract: A driving apparatus for raising and lowering an absorber rod within a nuclear reactor pressure vessel. The apparatus comprises a driving system which includes a motor-driven flexible support member that is connected to the absorber rod through both a coupling element and a connecting element, and a storage means for storing any excess length of flexible support member. Both the driving system and the storage means are detachably enclosed within a desired gaseous environment that is isolated from the interior of the pressure vessel by a screening plug having a passageway therein through which the connecting element is disposed for movement between an upper end position and a lower end position.