Patent Number: 041837843
Section: summary

BACKGROUND OF THE INVENTION The present invention pertains to a nuclear reactor plant with a prestressed concrete vessel, comprising a high temperature reactor with closed gas coolant circuit for the direct drive of at least one gas turbo apparatus comprising a turbine and a compressor, heat exchangers, and gas lines between the single circuit components. The high temperature reactor is arranged in a cavity, positioned in the center of the prestressed concrete vessel, the heat exchangers and the gas lines are installed in recesses in the wall of the prestressed concrete vessel, and each gas turbo apparatus is arranged in a turbine duct, led horizontally or vertically through the prestressed concrete vessel. Such a plant, in which the nuclear reactor, gas turbo apparatus and the other associated circuit components are arranged in a common pressure vessel (integrated construction), has the advantage that only the mechanical or electrical power produced and the coolant which has not come in contact with the contaminated gas need be led out of the prestressed concrete vessel. Therefore, the space outside the concrete vessel is practically completely protected from contaminated gas and the space inside of the prestressed concrete vessel is optimally used. It can be very conducive to accomplishing the latter goal, if the heated working medium is not led to only one relatively large gas turbo apparatus, as it is provided in most of the nuclear reactors with closed gas coolant circuit, but if several smaller gas turbo units are arranged in the prestressed concrete vessel. These are coupled by the nuclear reactor and form in each case, together with the heat exchangers, an individual circuit for the utilization of heat (loop). Furthermore, special connection elements between the single parts of the plant which carry active gas are avoided by the integrated construction. This works out very favorably in the construction and operation of high temperature reactors. Therefore, the integrated construction is preferred in a great number of special nuclear power plants. German Auslegeschrift No. 1,614,610 is stated as an example of a nuclear power plant having only one circuit for the utilization of heat. The concrete vessel, shown there, has two closed pressurized chambers, one which houses the reactor and the other which serves as a machine chamber. The working medium is led in lines, which penetrate the dividing wall between the both pressurized chambers, from the reactor to the turbine and from the compressor back again in an annular space below the reactor core. It is difficult to realize technically this so-called Igloo-type of construction, and the nuclear power plant does not work very economically, as a result of the arrangement principle. Nuclear power plants of an integrated type of construction with several circuits for the utilization of heat (loops) are described in German Auslegeschriften (DAS) No. 1,764,355, and No. 1,806,471 and Offenlegungsschriften (DOS) No. 1,746,249, and No. 2,062,934. The three last-named patent applications disclose a nuclear power plant in which the turbine aggregates and the heat exchangers are arranged in parallel vertical bores in the pressure vessel wall and in which the single loops form groups symmetrically around the nuclear reactor, which is situated in a central cavity. Both in the wall of the pressure vessel as well as in the spaces between the circuit components, there are provided passages for the coolant. Each loop can be installed with all associated components in one and the same vertical bore (DAS No. 1,806,471) or the heat exchangers, turbines and compressors of each loop are in each case arranged in a separate bore. (DOS No. 1,764,249). The above-mentioned DOS No. 1,764,355 discloses a nuclear power plant in which the circuit components of each loop are connected with each other by tubular channels. On the whole, two loops are provided. All heat exchangers are installed around the nuclear reactor in shaft-like recesses of the vessel wall, while both turbines and the associated compressor are arranged in one cavity below the nuclear reactor, in which there is also situated the gas distributing system for the heat exchangers. The turbines are arranged parallel to each other. As already mentioned, the integrated type of construction does permit a good efficient usage of the prestressed concrete vessel, which moreover can be held relatively small in its measurements by an especially skillful arrangement of the individual circuit components. Thereby, a great role is played by the installation of the gas turbo unit or units if a plant with several loops is involved. As for all other circuit components, the demand is present also for the gas turbo units that they are readily accessible for inspection and maintenance and that they can be removed from the outside, in case of repairs. SUMMARY OF THE INVENTION Therefore, it is an object of the invention to provide an improved nuclear reactor plant of the type described above. It is also an object of the invention to provide such a plant wherein the accessibility and the detachability of the gas turbo units are ensured by the special arrangement and anchoring of each gas turbo unit in its respective turbine duct and by special elements connecting the turbine unit to the coolant circuit. In accomplishing the foregoing objects, there has been provided in accordance with the present invention a nuclear reactor plant, comprising: a prestressed concrete pressure vessel; a high temperature reactor arranged in a first central cavity within the vessel; a closed gas cooling circuit including at least one housed gas turbo unit arranged in a turbine duct in the wall of the vessel, said unit including a turbine and a compressor and having detachable bearings; means for exchanging heat and means for transporting gas in said cooling circuit including hot gas from the reactor to the turbine, said heat exchange means and said gas transport means being arranged in recesses in the wall of the vessel; means for forming a detachable plug-in type connection between the hot gas transport means and each turbo unit; means, positioned at the edge of the turbine duct, for connecting all remaining gas transport means to the turbo unit; means, including peripheral sealing members positioned between the inside wall of the turbine duct and the outer housing of the turbo unit, for separating each of the remaining gas transport means from each other; means for detachably connecting each turbo unit to the inside of its turbine duct; remote control means for detaching these connecting means; means, including at least one lifting device controllable from outside of the vessel through a bore in the wall of the vessel, for dismounting each turbo unit from within its turbine duct; means for detaching from outside of the vessel all connections to each turbo unit which must be removed in order for removal of the turbo unit from its turbine duct; and means, including a duct through the wall of the vessel, for gaining access to each bearing of each turbo unit. In a preferred embodiment, the plug-in type connection means comprises a hot gas conduit having a telescoping portion adjacent the turbine and means for operating the telescoping portion by remote control. Also, the closed gas cooling circuit preferably comprises a plurality of identical loops, each loop comprising a gas turbo unit, heat exchange means and gas transport means, and wherein the turbine ducts for each of these gas turbo units are arranged below the reactor cavity in a horizontal plane and are arranged symetrically, preferably radially to the vertical center axis of the vessel.