GB1018618A - Improvements relating to nuclear reactors - Google Patents

Abstract

1,018,618. Handling nuclear fuel elements. ENGLISH ELECTRIC CO. Ltd. Feb. 13, 1963 [Feb. 14, 1962], No. 5631/62. Heading G6C. Storage equipment in a nuclear reactor for storing and cooling fuel elements after their removal from the reactor core includes elementcontaining means arranged to receive and hold the elements and to contain also a protective fluid, and cooling means for allowing a coolant gas at substantially atmospheric pressure and at a temperature substantially below that of the fuel elements, to circulate by convection around the outside of the element-containing means so as to cause the fuel elements to be cooled by only indirect heat exchange with the coolant gas, the interior of the element containing means and the fuel elements contained therein being sealed from the parts of the equipment containing the coolant gas. As shown in Fig. 1, a compartment 13 in the lower part of a reactor comprising loadbearing, radiation-shielding concrete walls 10, a floor 11 and a roof 12 has horizontal beams 14 supported by their ends in the walls 10, a framework 15 carrying a header plate 16 being ttached to the beams 14. A number of storage tubes 18 are secured to the plate 16, each being closed at its lower end 18a and having its upper end sealed into a hole in the plate 16. A conical pressure vessel 20 is sealed to the periphery of the plate 16 and to the roof 12, and a discharge tube 21 leads down from means (not shown) for discharging the reactor, through a sealing plug 22 to charge/discharge equipment, indicated by the chain-dotted lines 23 for providing access between the discharge tube 21 and the storage tubes 18. In operation the discharge tube 21, the pressure vessel 20 and the storage tubes 18 all contain carbon dioxide gas at a pressure slightly higher than that of the atmosphere. Suitable means for sealing the tube 21 from the active part of the reactor, in which there will normally be gas at a much higher pressure, are provided, but are not shown. Spent fuel elements from the reactor are lowered by suitable means through the discharge tube 21 and the charge/discharge equipment 23 successively into selected storage tubes 18. The tubes 18 become heated and induce natural convection currents in the surrounding air, causing air to enter through an inlet 24, as shown by the arrows, and to flow up a central passage 34, then radially past the tubes 18 between horizontal baffleplates 33 and vertical baffle-plates 36,.upwardly adjacent a conical containment shield 30 and so to an outlet 26. Some air passes between the walls 10 and a steel thermal shield 27. Since the pressure vessel 20 and the tubes 18 are sealed on to the header plate 16, neither the carbon dioxide nor the fuel elements come into direct contact with the cooling air circulating in the compartment 13. The equipment can also be used for storing fuel elements after removal from a liquid-cooled nuclear reactor, the storage tubes then containing reactor cooling liquid provided the structure is made suitably for withstanding pressures applied by the liquid.