Patent Number: 041994051
Section: claims

1. In a gas-cooled high temperature nuclear reactor having an axially elongated core with the axis of the core extending vertically and with the core having a lower region and an upper region, a graphite side reflector for said core extending in the axial direction thereof, said side reflector comprising an annular wall laterally adjacent to and laterally enclosing the outer surface of said core and having a radially inner surface and a radially outer surface relative to the axis of the core, said wall comprising a plurality of superosed annular layers, each said layer comprising a plurality of blocks with each said block extending continuously in a radial direction of the core from the inner surface to the outer surface of said reflector with each said block having a radially inner face forming a portion of the radially inner surface of said reflector, at least said blocks in said wall enclosing the upper region of said core having recesses extending into the inner face of said block with said recesses extending generally in the direction from the radially inner surface toward the radially outer surfaces of said side reflector, said recess arranged in two sets with the recesses of one set extending transversely across the recesses in the other set. 2. In a gas-cooled high-temperature nuclear reactor, the reflector according to claim 1, comprising a plurality of superimposed layers of blocks joined together to form closed rings. 3. In a gas-cooled high temperature nuclear reactor, the reflector according to claim 1, wherein said two sets of recesses consist of a grating of vertically and horizontally extending sets of rectilinear slits. 4. In a gas-cooled high temperature nuclear reactor, the reflector according to claim 3, wherein said slits of each set are at equal spacings from one another. 5. In a gas-cooled high temperature nuclear reactor, the reflector according to claim 3, wherein at least one of the width and depth of said vertically extending slits, at least of said blocks disposed in said upper core region, is greater than that of said horizontally extending slits. 6. In a gas-cooled high-temperature nuclear reactor, the reflector according to claim 1, wherein said core comprises a plurality of spherical fuel elements, and the width of said slits is smaller than the diameter of said fuel elements. 7. In a gas-cooled high-temperature nuclear reactor, the reflector according to claim 1, wherein the inner face of said blocks have a discontinuity pattern superimposed on said sets of slits. 8. In a gas-cooled high-temperature nuclear reactor, the reflector according to claim 7, wherein said discontinuity pattern comprises one discontinuity in the form of a truncated conical depression having a depth less than that of said slits in said inner face of each said block. 9. In a gas-cooled high-temperature nuclear reactor, the reflector according to claim 1, wherein the depth of each of said slits is between 20 and 200 mm.