Abstract: A nuclear reactor plant housed in a steel pressure vessel with a small high temperature reactor, together with a steam generator arranged over said reactor and with at least two circulating blowers connected in parallel with each other and following the steam generator in line and is provided with a decay heat removal system located in the primary loop. This system is arranged above the steam generator and a shut-off device is provided between the two component. The shut-off device, which may actuated both passively--by difference pressure--and actively, by means of a drive, is designed so that in normal operation no hot gas may enter the decay heat removal system. In the decay heat removal mode the hot gas is conducted into the decay heat removal system and the steam generator is closed off the hot gas. Simultaneously, the cold gas coming from the decay heat removal system is returned through the steam generator or a gas conduit parallel to it, to the reactor core.

Abstract: A nuclear reactor plant housed in a steel pressure vessel comprises a small high temperature reactor and a He/He heat exchanger located above the reactor, preferably followed by two circulating blowers connected in parallel. The installation further comprises at least one decay heat removal system, following in line the He/He heat exchanger in the direction of flow and with the entire flow of primary helium constantly flowing through it. In a preferred embodiment, the He/He heat exchanger is made up of two concentrically arranged coil bundles connected in succession, through which both the primary and the secondary helium are flowing in opposing directions.

Abstract: A low capacity nuclear reactor with spherical fuel elements in a subterranean configuration. The reactor is characterized by a compact construction and extensive elimination of active operating devices, such as charging installation, gas purification devices, regulating systems and safety systems. It is particularly suitable for the generation of thermal energy for heating purposes. A core vessel contains a pile of fuel elements also contains a portion of the graphite bottom and side reflector. Channels are provided in the part of the side reflector located inside the core vessel. Trim and shutdown rods are contained in the channels. The roof reflector rests on the stationary pile of fuel elements. The entire core vessel together with the components contained therein is removed following burnoff of the fuel elements. The heat generated in the core is transferred to a cooling system mounted on the inside of a pressure vessel enclosing the nuclear reactor by a cooling gas which flows from top to bottom.

Abstract: Gas-cooled nuclear reactors include circulation systems for cooling gas to remove the heat generated in the reactor core. An improved arrangement includes a plurality of steam generators in a horizontal plane located above the horizontal plane of the reactor core. The cooling gas circulates from the bottom of the reactor core to the top. Improved heat removal is accomplished in this manner as the heated cooling gas enters the steam generators after passage through the reactor core without undergoing further circulation in a horizontal or inverse vertical direction.

Abstract: Disclosed is a prestressed concrete pressure vessel having a vessel opening which is closed by a concrete cover. Two separate gaskets are disposed between the cover and the pressure vessel, and bordering on an annular channel. The annular channel is connected with a gas detector by means of a connecting channel. At the same time, the inner area of the cover rises from the pressure vessel at a slight angle. The vertical prestress by which the cover is pressed down is larger than the force acting against it (the internal pressure). Additionally, the horizontal annular prestress of the cover is larger in its upper region than in the lower region. In this manner, a constant seal is combined with means for monitoring the seal.

Abstract: The invention concerns a steam generator heated by the cooling gas of a nuclear reactor and arranged in the reactor pressure vessel within a vertical shaft. A blower associated with the steam generator is installed above it. The hot gas is conducted to the steam generator in the form of a helical bundle in the downward direction, with the hot gas being conducted initially downward through an annular channel and entering the bundle of heat exchanger tubes at a uniform velocity. The annular channel is sealed in upward direction by means of a sliding seal, which also serves as an earthquake support. In order to provide access to the feed water and live steam lines in view of the blower arranged on top, the two lines are conducted laterally out of and through the reactor pressure vessel. By means of the special fixation of the individual tubes of the heat exchanger bundle in vertical plates and the presence of an expansion zone for the recycling pipes, differential thermal expansion may be kept small.

Abstract: A graphite roof reflector for a small, high temperature reactor is arranged under the hot gas collector space and is therefore exposed to high thermal and radiation loads. In order to make possible the satisfactory support over the entire operating life of the reactor, the roof reflector is assembled from a center part and an annular part, which are supported in a different manner. The annular part is supported on the side reflector of the reactor. The center part is suspended by means of tie rods from a cover located over the hot gas collector space. The tie rods are placed into bores of the cover through which cold gas flows.

Abstract: Disclosed is a nuclear power plant comprising a high-temperature pebble bed reactor contained in a cylindrical steel pressure vessel in which an upper part of the cylindrical steel pressure vessel, which contains a heat utilization system, is retracted and equipped with a cover upon which circulating blowers are placed. The heat utilization system comprises, in a known manner, a single steam generator. The steam generator comprises at least two sub-systems independent of one another, with their own distributors and collectors, and with their own inlet and outlet lines. A first shut-down arrangement comprises a plurality of absorber rods insertable into bores of the side reflector from above and comprises rod drives arranged outside the steel pressure vessel in the area of its retracted upper part. A second shut-down arrangement comprises small absorber spheres for introducing into the core of the reactor, and several storage containers and annular conduits for said spheres.

Abstract: A cost-effective configuration of a metal liner for a reinforced concrete pressure vessel is disclosed wherein only stud shear connectors and cooling tubes of the liner cooling system are used to anchor the liner and the passages provided in the liner and the wall of the vessel. In the areas of the introduction of forces, stud connectors of different stud rigidities are used. In the anchoring of loads which is again effected by stud connectors only, further transmission is obtained by means of reinforcing rods.

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 barrier system for a high temperature reactor. The reactor utilizes spherical fuel elements consisting of coated particles of a fissionable material embedded in a graphite matrix, the coating forming a first safety barrier against the release of fissionable material, and the graphite matrix a second such safety barrier. The reactor is surrounded by a prestressed concrete pressure vessel clad on the inside with a metal liner. The metal liner acts as a third safety barrier, while the concrete body of the prestressed concrete pressure vessel forms the fourth, and outermost safety barrier. A plurality of passages are located in the pressure vessel which are closed off by closure means. The closure means provide sealment between the third and fourth barriers in the area of the passages. By utilizing the concrete pressure vessel as a safety barrier in this manner, the need for a separate protective reactor housing is eliminated.

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: Process for the construction of a nuclear reactor having a reinforced concrete pressure vessel, comprising utilization of a corset frame to support the cavity liner, closing off the reactor cavity and installing the reactor components under "clean conditions", simultaneous to the layer-by-layer pouring of the walls and top of the reinforced concrete pressure vessel. The erection of the supporting corset substantially reduces the overall assembly time of the nuclear power station without involving additional expense.

Abstract: A passage through a reinforced concrete pressure vessel is provided, wherein the tolerance ranges required for the fastening of the components in the passage may be produced safely and without excessive expenditures. This is achieved by an arrangement including a lining having a first, outer tube resting against the concrete and a second tube arranged within the first tube.

Abstract: A support structure for a nuclear reactor is disclosed comprising a primary support element connected with the roof of the pressure vessel and a secondary support element joined with the primary support element. The thermal roof shield and the roof reflector are connected to the secondary support element.

Abstract: A gas cooled, high temperature nuclear reactor is provided with a base plate arranged under the reactor core and over the bottom of the prestressed concrete pressure vessel serving as the bottom shield. The bottom shield comprises at least two plates arranged coaxially with respect to each other, one above the other. Each plate comprises several partially interconnected parts with the lower plate being placed at an axial and vertical distance from the bottom liner of the prestressed concrete pressure vessel and also from the upper plate.

Abstract: A closure for a prestressed high-pressure vessel comprises an anchoring ring surrounding the opening of the prestressed concrete pressure vessel, a plurality of axial stressing cables and a plurality of cover stressing cables. The cover is separately prestressed and simultaneously anchored to the prestressed concrete pressure vessel. The anchoring rings on the concret need for releasing the axial stressing cables of the prestressed concrete pressure vessel.

Abstract: A pressure vessel for a nuclear reactor comprises a reinforced concrete vessel with at least one open area located in the wall of the concrete vessel, a lining means anchored on the inside surface of the concrete vessel and the opea area for protection of the surfaces and at least one expansion space in the concrete vessel immediately adjacent the lining means to permit movement of the lining means and distribution of the stresses in the lining means under various reactor conditions.

Abstract: A support structure for a nuclear power station having a prestressed cylindrical vessel comprising an annular ring of supports on a support wall and foundation wherein the prestressed cylindrical vessel rests on the ring of supports is disclosed. The supports, through their defined distances from each other, provide a constant cooling flow of the supports and a constant temperature over the entire operating period of the power station. This results in supports that are maintenance-free. The supports are constructed of plastic washers with steel inserts and are of sufficient height such that in the case of earthquakes, maximum vibrations of the reinforced concrete pressure vessel may be absorbed within an accurately set terminal boundary of the annular support wall.

Abstract: A support structure for the core of a gas cooled high temperature reactor utilizes a plurality of compression members arranged in an annular space between a plurality of graphite blocks forming the roof, bottom and cylindrical side walls of a reflector surrounding the reactor core and a thermal shield surrounding the reflector. Each compression member comprises a compression body, a first bolt part having the configuration of a threaded rod, a threaded area on the inner surface of the compression body for receiving the threaded bolt part, a second bolt part having the configuration of a piston, a sliding area on the inner surface of the compression body for receiving the piston bolt part, and means for producing a compressive force between the piston bolt part and the compression body. The plurality of compression members are attached to the reflector and thermal shield by way of a plurality of ball-and-socket joints.