An apparatus for detecting and monitoring of leaks in gasgekuehlten atom accidents at reactors

摘要

819,366. Monitoring fuel channels in nuclear reactors. COMMISSARIAT A L'ENERGIE ATOMIQUE. May 24, 1956 [June 9, 1955], No. 16136/56. Class 39(4). A device for detecting leaks in the slugs in a gas-cooled nuclear reactor detects the variations in radio-activity of the cooling gas streams, means being provided for successively testing gas streams from each of the channels. The graphite block 1 in an air-cooled reactor is provided with channels 2 in which gas-tight casings 3 enclose uranium. Valves 7 in the concrete shield 4 have collecting elements 5 supplying coolant air samples by pipes 8 to external detector apparatus. Electrically actuated valves 9 controlled by a switch 11 successively allow the air samples to pass through a dust filter 18 to a chamber 13 containing a counter 12 sensitive to beta rays of the fission products and to gamma rays. The counter 12 has thick walls to reduce the sensitivity to ASP41/SP normally present. A band 23 having active carbon to adsorb gaseous radioactive products moves so as to present a fresh filter portion for every channel tested. An air pump 16 provides circulation and discharge to stack 17. A device 14 amplifies the counter impulses and provides voltage feed to a recording apparatus 15. When the radio-activity of the coolant air is below a predetermined limit the switch 11 rotates at constant speed and the activity in each channel is measured successively. If the activity in a channel exceeds this limit a contact 19 causes the switch 11 to stop and operates an audible alarm 21 and a lamp 20 indicating the channel concerned. By means not described, air is then collected continuously from this channel and tested and the above apparatus is again started, to test the remaining channels.