GB916820A - Improvements in or relating to fuel feeding arrangements for nuclear reactors - Google Patents

Abstract

916,820. Servicing reactors. GENERAL ELECTRIC CO. Ltd. Feb. 29, 1960 [Feb. 27, 1959], No. 6935/59. Class 39 (4). In a reactor in which fuel element channels in the core are refuelled from their lower ends whilst the reactor is in operation the fluid coolant is arranged to enter that channel which is being serviced at a lower temperature than that entering the remaining channels whereby the mass flow of coolant through that channel may be reduced thereby reducing the risk of blowing a fuel element out of that channel during the withdrawing of a stack of fuel elements. As shown, the reactor pressure vessel 1 has a number of standpipes 3 (only one shown) depending therefrom, each fuel element channel in the core (not shown) having an extension 23 to which a swivelling duct 7 of a charging machine 2 may be coupled. The charging machine is as described in Specification 844,764 and has a charge tube 8 which may be extended from the charging machine vessel 9, a flange 5 on the vessel 9 making a gas-tight connection with a flange 4 in the selected standpipe 3. The duct 7 forms a continuation of a duct 10 with which a tube 11 may be aligned, the tube 11 being one of a number of similar tubes provided by a fuel element storage magazine. A tube 12 houses a chain which conveys the fuel elements from or into the tube 11 and along the duct 10. The chain may be as disclosed in Specification 893,487. A tube 16 interposed between the duct 10 and tube 8 extends through a header 17 coupled by ducting 18 to a water cooler 19. In operation the vessel 9 is gas-pressurized to a pressure similar to that in the reactor vessel 1, a valve in the flange 5 is opened, the duct 7 is connected to the extension 23 and a blower 20 is started. Gas is thereby withdrawn from the vessel 1 through the space between tubes 8, 16 and enters the cooler 19, part of the gas leaving through duct 22 and entering vessel 9 and part leaving through duct 21 and passing through tubes 11, 10, 7, 23 to cool the fuel element channel. The gas in vessel 9. returns partly through the space between tubes 10, 16 and partly through the space between tube 8 and standpipe 3. This gas provides a cool buffer between the cool returning gas in tube 10 and the hot entering gas and also prevents overheating of the standpipe and concrete shield 14. Specifications 785,945 and 789,022 also are referred to.