GB1095545A - - Google Patents

Abstract

1,095,545. Fuel elements. UNITED KING- DOM ATOMIC ENERGY AUTHORITY. Aug. 16, 1965 [Sept. 2, 1964], No. 35923/64. Heading G6C. A transverse bracing grid for a cluster-type fuel element comprises undulating strip material attached to a bounding rim, the strip material being of two superimposed spaced layers and arranged so that loops of one layer co-operate with loops of the other layer to define a plurality of cells, each cell for containing a fuel rod. In the embodiment shown in Fig. 2, a fuel element comprises thirty-six fuel rods 1 arranged on four concentric pitch circles and includes a central tube. Each rod 1 has three parallel wires 16 helically wrapped over the length of the rod or disposed parallel with its longitudinal axis. Transverse bracing grids which are disposed at intervals intermediate the ends of the fuel element each comprise a rim 5 and a central ferrule 6 of thin stainless steel strip, the ferrule 6 being welded to the central tube of the fuel element. The annulus between the rim 5 and the ferrule 6 contains two superimposed spaced layers of thin stainless steel undulating strip. Each layer comprises three continuous strips, each strip being lap jointed as at 9 and arranged so that the layers co-operate to define four concentric annuli 10, 11, 12, 13 of cells for the fuel rods 1. In each layer 7, 8 contiguous loops of adjoining strips are joined by welding as at 14 and the strips defining the annuli 10, 11 of cells of each layer 7, 8 are interconnected by further strips 15. The strips defining the outer and inner annuli 10, 13 of cells of each layer 7, 8 are welded to the rim 5 and the ferrule 6 respectively. In an alternative construction, the strips are formed with concyclic projections 17 projecting radially inwardly of the cells to bear on the surfaces of the fuel rods 1.