GB1402936A - Nuclear reactor fuel element assemblies - Google Patents

Abstract

1402936 Fuel elements UNITED KINGDOM ATOMIC ENERGY AUTHORITY 13 Dec 1973 [14 Dec 1972] 57814/72 Addition to 1283604 Heading G6C A nuclear fuel assembly comprises a bundle of fuel pins having wire wrap spacing means and enclosed in a peripheral casing through which liquid coolant can be passed over the surfaces of the fuel pins, the casing having a flexible lining which co-operates with the casing to define an interspace for containing a jacket of pressurized gas, the lining being inwardly flexible by the pressureized gas to embrace the bundle of fuel pins. The spacing means for the fuel pins may comprise helical wire wrapping of square cross-section. In one embodiment, the easing 1 has a lining 3 sealed at its upper end to the casing but open at its lower end. The lining 3 comprises a flexible membrane longitudinally corrugated over its upper half generally complementary to the contour of the bundle of fuel pins 2. Its lower half is without corrugations and is overlaid by an inverted skirt 4 sealed to the casing 1 adjacent the free end of the lining 3. The skirt 4 is corrugated generally complementarily to the countour of the bundle of fuel pins 2. In use in a reactor core, the free end of the lining 3 is screened by the skirt 4 from the direct upward flow of coolant through the casing 1. However, the passage bounded by the plane surface of the lining 3 and the corrugations of the skirt 4 serves to conduct coolant to inside the lining 3 to compress argon gas between the corrugations of the lining 3 and the casing 1, but providing pressure relief when the reactor is at full power thereby reducing the compressive force exerted on the bundle.