GB1088786A - Nuclear fuel element - Google Patents

Abstract

1,088,786. Fuel elements. COMMISSARIAT A L'ENERGIE ATOMIQUE. July 1, 1966 [July 9, 1965], No. 29605/66. Heading G6C. A method of fabricating a nuclear fuel element comprises the successive stages of encasing a fuel rod in a can, fitting end caps machined to their final shape into the can, employing temporary units for plugging recesses in the end caps which are subsequently intended to accommodate final components for centring the fuel elements with respect to adjacent fuel elements, these temporary units being formed of a material having a coefficient of thermal expansion equal or very close to that of the end caps, applying the can in tight contact with the fuel rod, and replacing the temporary units with the final centring components after completion of the fabrication process. The temporary units may be formed of the same material as the end caps, and they are preferably shaped so as to protect welded joints between the can and the end caps during subsequent canning and handling operations. As described, a tubular fuel rod is encased in a can sealed by thin-walled end caps of the hollow inset type separated from the fuel rod by insulating discs. A final centring component placed within each end cap recess has the inner end abutting the end cap while the outer end is rounded so as to co-operate with a corresponding component carried by an adjacent fuel element, and is fitted with a threaded bushing which is screwed into a tapped portion of the recess. The contact surfaces between the end cap on the one hand and the insulating disc and the centring component on the other hand are preferably roughened to increase friction and reduce the risk of creep.