Patent Number: 059463660
Section: summary

BACKGROUND OF THE INVENTION FIELD OF THE INVENTION The invention relates to a nuclear reactor including a core melt collection chamber having walls with multilevel protective layers, including one layer part made of refractory concrete and another layer part made of ceramic bricks, the protective layers being anchored to the structural concrete of the collection chamber. German Published, Non-Prosecuted Patent Application DE 43 39 904 A1, corresponding to U.S. application Ser. No. 08/651,307, filed May 22, 1996, discloses a nuclear reactor of the above-mentioned type, in which the layer parts are fastened to the structural concrete with common tensile anchors, with one such tensile anchor being provided for each ceramic brick. That structure gives rise to a comparatively high degree of outlay for construction, because the tensile anchors must be positioned as accurately as possible with regard to expansion joints. In the known reactor, additional anchoring points may be provided in the layer part made of refractory concrete. They are encapsulated by refractory concrete. SUMMARY OF THE INVENTION It is accordingly an object of the invention to provide a nuclear reactor with a collection chamber for core melt, which overcomes the hereinafore-mentioned disadvantages of the heretofore-known devices of this general type, which in contrast thereto achieves a structural simplification, in particular a reduction in the number of fastening points and which at the same time ensures that the core melt cannot lead to loosening of an anchoring of structural concrete. With the foregoing and other objects in view there is provided, in accordance with the invention, a nuclear reactor, comprising a core melt collection chamber having at least one wall with structural concrete and a multilevel protective layer; the protective layer having one layer part made of refractory concrete and another layer part made of ceramic bricks, the layer parts anchored to the structural concrete; the layer part made of refractory concrete constructed as prefabricated blocks jointed together and fastened to the structural concrete; and the layer part made of ceramic bricks braced to the blocks of the layer part made of refractory concrete. The jointing, in particular a tongue and groove engagement, of the prefabricated blocks permits a considerable reduction in the number of fastening points, without detrimentally affecting the structural stability. It is furthermore possible for the ceramic bricks to be braced to the blocks, so as to make it possible to distribute the anchoring of the layer parts, which is advantageous from the technical safety point of view. In accordance with another feature of the invention, the ceramic bricks are jointed together, for example in a tongue and groove manner or with alternately oriented T profiles, and are only braced at individual points. This makes it possible to reduce the number of fastening points to an even greater extent. The blocks of the refractory layer can be fastened with a known device. In accordance with a further feature of the invention, the blocks of refractory concrete are held with tensioning elements which are concreted into the structural concrete and engage through holes in the blocks. In accordance with an added feature of the invention, the blocks are braced with ceramic anchors. In accordance with an additional feature of the invention, the ceramic anchors advantageously contain screw-threaded sleeves which facilitate assembly and improve the introduction of the retention forces. In accordance with yet another feature of the invention, the ceramic bricks are fastened with T-anchors which are seated in C-rails. An extensive distribution of the retention forces is thereby again achieved with a favorable assembly. In accordance with a concomitant feature of the invention, in order to prevent the penetration of core melt, as well as to protect the anchoring elements, the joints between the ceramic bricks are filled with zircon felt. The joints thereby serve for the thermal expansion of the zircon bricks. Other features which are considered as characteristic for the invention are set forth in the appended claims. Although the invention is illustrated and described herein as embodied in a nuclear reactor with a collection chamber for core melt, it is nevertheless not intended to be limited to the details shown, since various modifications and structural changes may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims. The construction and method of operation of the invention, however, together with additional objects and advantages thereof will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings.