GB1013541A - Improvements in fuel element cans for nuclear reactors - Google Patents

Abstract

1,013,541. Fuel elements. ENGLISH ELECTRIC CO. Ltd. April 4, 1962 [April 6, 1961], Nos. 12360/61 and 12361/61. Heading G6C. A fuel element assembly for a nuclear reactor includes at least one radial deflector vane, at least a portion of which is inclined obliquely to a plane containing the axis of the assembly so as, when the assembly is in position in a fuel channel of the reactor, to deflect the flow of coolant and create an asymmetrical pressure distribution around the assembly whereby to create a lateral stabilizing force on the assembly. In one embodiment, the assembly includes a cylindrical hollow fuel can 10 with helical cooling fins 13 divided into zones by four equallyspaced splitters 14. The splitters are held in position by bracing strips 15, and have axiallyextending flanges 16 in the downstream portion of the assembly (Fig. 2) and axially-extending flanges 17, 18 in the upstream portion, the direction of coolant flow being as indicated by the arrows in Fig. 1. The flanges 16 on diametrically opposite splitters are arranged in opposite senses in order to produce an asymmetrical aerodynamic loading by creating lateral forces on the assembly. Angular deflector vanes 19 are attached to the downstream ends of the splitters 14, diametrically opposite vanes having their inclined portions parallel so as to create an asymmetrical axial pressure distribution producing a lateral stabilizing force on the assembly which acts in the same direction as that produced by the asymmetrical loading due to the flanges 16. The splitters 14 have raised portions forming castellations 22 at intervals along their length. The flanges 17, 18 maintain a smaller resultant force on the lower part of the assembly than on the upper part, the flanges 18 also acting as strengthening members, thereby ensuring that there is a net lateral force at the junction of adjacent assemblies which might not be the case if the flanges 16 extended over the whole length of each splitter and adjacent assemblies were positioned out of phase with each other. In another embodiment described, the splitters 14 are of T-section and produce no asymmetric loading. Mention is also made of an assembly in which an axiallyextending gap is formed in one or more of the splitters and a deflector vane fitted in the gap or circumferentially in line with the gap. The deflector vanes, if at one end of the assembly, may be at the upstream end instead of the downstream end. Any suitable number of vanes may be fitted and they need not necessarily be spaced equally around the fuel can. A deflector vane may be fitted so as to be out of line with any splitters that may be fitted and may be provided even in the absence of splitters.