Patent Number: 041994051
Section: description

The side reflector is formed of a plurality of layers of superimposed rings, which consist of blocks disposed alongside one another, of which three are shown in FIG. 1. The inner and outer end faces of all the blocks form the preferably cylindrical inner and outer face respectively of the side reflector, which are concentric to each other. According to FIG. 1, which shows the formation of the inner end face of the blocks in two preferred forms, the vertical side faces of each block, which adjoin the next adjacent blocks, extend in a wedge-shaped pattern towards the centre of the cylinder formed by the side reflector, so that each block as the sector shape of a "piece of cake" with the point cut off. The upper and lower face of each block are plane and parallel. As can be seen especially from FIGS. 2a and 2b, the inner end face of the central block 5 illustrated in FIG. 1 is furnished with two mutually perpendicular sets of slits 6 and 7, which can be made for example by sawing, the width of each slit 6 and 7 being equal to the thickness of the saw blade. In order, in nuclear reactors charged with spherical fuel elements, to prevent the densest possible packing of the spheres 8, a discontinuity 9 is formed as shown in FIGS. 2a and 2b in the end face of each block 5, centrally placed and superimposed upon the sets of slits 6 and 7, this discontinuity in the example shown having the form of a truncated conical depression. Preferably, the depression extends at a maximum to the base of the slit, which is situated radially outwards between 20 and 200 m from the machined inner end face of the block 5. The block 11 shown at the left in FIG. 1 differs in the form of its end inner face from block 5, in that the vertical slits 12 extending perpendicularly to the slits 7 are of larger width than the slits 6 and 7, thus producing, amongst other things, the already explained by-pass advantages. In this connection, it is only necessary to emphasise once again that in a form as represented by block 11, the thermal reservoir existing in the side reflector blocks in total is utilised to an optimum extent especially in the case of a shutdown or failure of cooling, since the radiation influences the heat transfer by the difference of the fourth powers of the temperatures, which in the case of this example of embodiment therefore leads to an enormous emission, because, if the cooling is absent, the by-pass rendered possible by the wider vertical slits 12 lead to a comparatively high temperature difference. As also shown in FIG. 1, vertical grooves 14 are provided in the mutually facing, vertical lateral surfaces 13 of each block, these grooves 14 forming in pairs vertical passages, into which keys for fixing the blocks and interrupting the outwardly radiating, continuous gaps between adjacent blocks, are introduced.