Patent Number: 046613137
Section: summary

BACKGROUND OF THE INVENTION 1. Field of the Invention The invention relates to a metal liner for the internal lining of the cylindrical cavity of a reinforced concrete pressure vessel cavity for a nuclear reactor installation. Gas cooled, high temperature nuclear reactors are exemplary of this type of lining and cylindrical cavity area. The liner is anchored to the wall of the vessel by means of stud shear connectors and with cooling tubes welded to it on the concrete side. A plurality of passages are provided through the liner and the wall of the vessel. The passages are lined with a steel tube. 2. Background of the Art It is known in the prior art to anchor in a reinforced concrete pressure vessel intended to house a nuclear reactor, lined with a metal liner, means of suitable fasteners, such as stud shear connectors, ribs or claws in the concrete. This prevents the bulging of the liner in case of a pressure drop inside the vessel. Reinforced concrete pressure vessels are described, for example, in West German Published Application No. 2227394 and West German Offenlegungsshrift Nos. 2921707 and 3009826. To avoid excessive thermal loads on the concrete, the known vessels are equipped with a thermal protection system, consisting of a plurality of cooling tubes welded to the liner on the side of the concrete. Both the walls of the reinforced concrete pressure vessel and the liner must be provided with a series of passages to make the installation and removal of reactor components, the insertion of shutdown and control rods, the introduction of measuring instruments and the in- and outflow of the primary or the secondary medium possible. The passages are conventionally equipped with a steel lining as shown in West German Offenlegungsschrift No. 3009826. Reinforced concrete pressure vessels have further been proposed, wherein the liner is not anchored in the vessel. To prevent the bulging of the liner in case of a pressure drop inside the vessel or stressing by varying temperatures, special measures must be taken in the case of such pressure vessels. These may consist of the arrangement of a plurality of steel scaffoldings having the necessary rigidity on the inner side of the liner, as described in West German Pat. No. 2717705. SUMMARY OF THE INVENTION The invention is an improvement on the liner described initially. One of the objects is to provide a cost-effective configuration for this known type of liner, which satisfies all requirements concerning mechanical strength and quality. According to the invention, the aforementioned object is attained by: (a) correlating the thickness of the liner with the grid of stud shear connectors, which in turn is determined by the spacing of the cooling tubes and the reinforcement of the concrete; (b) using, in addition to the stud shear connectors, the cooling tubes for the anchoring of the liner and arranging them so that they will have the highest support effect; (c) providing stud shear connectors with different bolt rigidities at the location of the introduction of forces; (d) utilizing, in the case of loads acting on the liner, anchoring means in the concrete comprising stud shear connectors only and providing reinforcing rods for the transfer of loads acting on the liner anchoring means; (e) anchoring the steel tubes of the passages in the concrete in a conventional manner by means of stud shear connectors and securing the steel tubes against being forced out by mounting cooling tubes by means of welding in the circumferential direction and by means of stud shear connectors, and (f) taking into account friction to anchor the liner in areas where it doubtlessly exsists. For anchoring the liner according to the invention, only stud shear connectors and the cooling tubes of the liner cooling system are used. In cooperation with a certain liner thickness, the stud shear connectors assure the necessary security against bulging. The use of ribs and claws as in conventional anchoring arrangements is eliminated as these represent heat bridges conducting excessive heat into the concrete and, therefore, requiring additional cooling. In addition, this elimination reduces the need for reinforcement. In the case of the steel tubes of the passages again, only stud shear connectors are used. The special elements used in conventional anchoring arrangements to secure against ejection are eliminated. This task is performed by means of the special arrangement of the welded cooling tubes, together with the additional stud shear connectors. In the locations where internal or external forces are introduced into the liner, favorable conditions may be created by adapting the stud rigidity of the individual stud shear connectors to the prevailing need. Friction is taken into consideration wherever it clearly exists. This is the case, for example, when the contact pressure is the result of internal pressure. In the area of passages, which penetrate the cover of the pressure vessel in a conventional manner and permit the insertion and retraction of absorber rods, the thickness of the liner is determined advantageously so that it is secure against bulging without additional anchorings. The steel tubes penetrating through the wall of the vessel and the liner of the passages may be inserted through the liner in the conventional manner. There are no convexities of the liner in this area which contribute to the economical manufacture of the liner. The radii of the transition areas of the liner from its cylindrical part to the bottom and roof liner are preferably chosen so that the anchoring of the liner with stud shear connectors alone is possible. Here again, in cases where it clearly exists, friction is taken into account. In the anchoring of loads, which as described above, is again effected by means of stud shear connectors only, it is appropriate to determine the length of the stud shear connectors as a function of the number of the reinforcing rods required for transmission of loads in the concrete. With greater stud lengths, for reasons of space, a larger number of reinforcing rods may be placed in the area of the introduction of loads. As mentioned above in order to obtain a favorable introduction of forces at the locations of their introduction, stud shear connectors of varying rigidity are employed. The variation in stud rigidity may be obtained in different ways. Thus, in the particular area involved, stud connectors with different stud diameters or different stud lengths may be used. But varying stud rigidities may also be obtained by providing recesses filled with a soft material (in the area of the stud/liner joints), in a conventional manner. These cavities without concrete restrict the contact of the stud shear connector to a certain length. Similar free spaces may be present further around the steel tubes of the passages in the area of their exit from the concrete of the vessel. They may be filled with a material of a lower elasticity. Their objective is to reduce the bending stress in the steel tubes. According to a further development of the invention, the liner may consist of flat metal plates, i.e. lining is effected with flatplates even in the curving areas of the reinforced concrete pressure vessel. This has the advantage that it is not necessary to form round the plates. Furthermore, the distortion due to welding is less, so that the stiffening structure may be much less expensive. The transition locations of the liner from its cylindrical part to the roof and bottom liners again may consist of at least one flat plate. By means of a special division of the plates of the cylindrical part of the liner, the transitions may have still another configuration. Thus, the individual plates of the cylindrical liner part may be joined with a seam at their centers in the vertical direction, and the plates are arranged so that their seaming edges are meeting a weld joint between two segments of the bottom and roof liner, while the welds of the individual plates impact the center of a segment. The horizontal edges of the individual plates are welded directly to the outer edges of the segments of the bottom and roof liners. The plate division proposed above eliminates cross welds.