Patent Number: 046559981
Section: description

DESCRIPTION OF THE PREFERRED EMBODIMENT The concrete vault enclosing the primary vesel of a sodium cooled fast breeder nuclear reactor is of generally cylindrical shape with a rounded base and an open top closed by a roof. For convenience, only a part of one side is illustrated in FIG. 1, viewed from the interior and designated 1. The construction of thermal insulation is similar for the vault base to that described for the vault side and is continuous therewith. The concrete has embedded in it at spaced intervals a plurality of pads 2, and aligned pads 2 carry a stanchion 3 extending in a vertical direction, there being a number of stanchions 3 spaced equally and parallel to one another. Each stanchion carries a number of spaced pegs 4, and it is arranged in this construction but is not limiting that a pair of pegs 4 at the same level but of two adjacent stanchions 3 serve to provide hanging support for a unit generally indicated by the reference numeral 3. Each unit 5 is constructed of sheet metal in box-like manner so as to include a contained void 6 and has on the outer side of the outer wall 7 defining the void 6 a pack 8 of heat insulating material, see particularly FIGS. 2 and 3. Each peg engages with a keyhole slot 10 in a leaf 9 (see FIG. 3) welded or otherwise secured to the inner boundary wall 11 of the void 6 so that the respective unit 5 is hung symmetrically from two pegs 4, see FIG. 1. The pack 8 is protected on its outside, which faces the outer surface of the primary vessel, not shown, by a sheet metal boundary 12. The units are arranged in adjoining manner both upwardly, downwardly and sideways so as to present a more or less continuous face to the outer surface of the primary vessel. At the joins it is arranged that there is interleaving, see particularly FIGS. 2 and 3. This is accomplished for the packs 8 of units 5, by lengthy projections 13 depending from the lower edge of the pack 8 of a unit 5 interleaving with lengthy projections 14 raised from the upper edge of the next adjoining, in a downward sense, pack 8 of the respective unit 5. Insofar as the voids 6 of adjacent units 5 are concerned, the lower edge 15 of a upper unit 5 is engaged in a forked portion 16 of the next adjoining, in a downward sense, unit 5. The expedients minimise radiation streaming and gas leakage between units 5. The units 5 are built up from the lowest to the highest rows at a time. The voids 6 are thus interconnected to form vertical ducts 17 in side-by-side relationship. As can be seen from FIG. 2, interconnection is avoided between units 5 which adjoin in horizontal manner, there being interleaving in the manner described for the stacked packs 8 of FIG. 3. The packs 8 have a simple overlap joint between sideways adjoining units 5. The spacing left between the concrete and the wall 11 serves to provide a static fluid volume 18 which can either be occupied by the same cooling fluid (eg a blanket gas) as is made to flow in ducts 17 by pumping, or can be occupied by another environmental atmosphere.