GB972474A - Improvements relating to automatic cooling gas control valves for gas-cooled nuclear reactors - Google Patents

Abstract

972,474. Fuelling reactors. FAIREY ENGINEERING Ltd. June 5,1963 [March 5, 19621, No. 8403/62. Heading G6C. In order to prevent blow out of the fuel elements remaining in a reactor core channel after the majority of the elements in that charnel have been removed by a grab, the upward flow of coolant gas through the channel is automatically reduced by a valve responsive to the gas temperature. The valve is mounted at the lower end of a charge shoot adapted for connection to the channel and controls the flow from the channel into the space enclosed by the pressure vessel. At the normal working temperature of the gas in the channel corresponding to a fully loaded channel the valve is fully open but it closes progressively as the temperature drops as the fuel elements are removed. As shown, the lower end of a charge shoot 13 has a tubular extension 10 provided with ports 27 and surrounded by a fixed sleeve 15 having ports 25. Three annular members 20, 23, 24 are secured to the sleeve 15 and each annular member has four arcuate bimetallic strips 30 anchored thereto by rivets 32. The other ends of the strips 30 of each group are riveted at 33 to a ring 28 of L-section. At the normal working temperature of the gas the strips 30 are deflected so that the rings 28 are raised as seen in the right-hand half of Fig. 1 and the ports 25 are not obstructed. On cooling of the gas, however, the strips unflex so that the rings 28 drop and substantially close the ports 25 as shown in the left hand half of Fig. 1