GB900235A - Improvements in or relating to nuclear reactor core support structures - Google Patents

Abstract

900,235. Nuclear reactors. GENERAL ELECTRIC CO. Ltd. Jan. 23, 1961 [Jan. 25, 1960], No. 2634/60. Class 39 (4). In a nuclear reactor core support structure of the kind comprising a core supporting platform, a grillage beneath the platform, and a peripheral support on which the grillage is mounted, the grillage comprises a symmetrical arrangement of beams welded to a common hub member at a central point and extending radially therefrom, the beams being supported towards their outer ends on the peripheral support. In Fig. 1, each beam 4 is a composite unit comprising upper and lower beam members, the lower beam member (not shown) being of catenary type. The two beam members are welded together at one end and to the central hub member 6 at the other, and are connected together by vertical columns (not shown); the lower beam members are preferably braced at their midpoints by transverse bracing members forming a hexagon concentric with the grillage. Considering the upper grid as composed of six 60 degrees sectors defined by every fourth beam, each sector includes a number of equally spaced parallel subsidiary beams 2 lying transversely to the radial beams and fixed to them. At the inner portion of each sector a rhombic plate 1 is jacked at four positions to one of the beams 2 and the hub 6, these positions being at the corners of a rectangle; two further plates 1 are next positioned in butting relationship to the first plate, these also being jacked at four positions 3 to two subsidiary beams 2, and so on until the platform has been built up. The central hub member 6 may be a cylindrical column having radial stubs to which the upper and lower radial beam members are welded. Diagonal bracing members may be provided between each pair of upper and lower radial beam members, and in this case. the central hub member may be conical. The outer ends of the radial beams are mounted on the peripheral support skirt 7. In a modification, the grillage comprises a single grid of deep sectional beams. Each beam 10, Fig. 2, is flame cut in one piece to provide upper and lower portions joined by diagonal portions. The central hub 14 is conical and is provided with upper and lower circular plates into which the inner ends of the beams 10 are slotted and welded. The annular support skirt 15 is slotted and the beams are located in these slots. A flat ring beam 16 is welded round the circumference of the grillage to strengthen it, to provide a surface on which to jack the outer support plates, and to provide an anchorage for a gas seal. Gusset plates 21 are provided between the ring beam and the radial beams and are fixed to the support skirt. As in the previous example, the radial beams support transverse beams to which the support plates are jacked. In addition the beams 10 are braced together by tie-rods, Fig. 3 (not shown). Specification 852,839 is referred to.