Patent GB-1129565-A (GB)
Title: Device for inserting an emergency control rod into a nuclear reactor
IPC: G21C7/20
Filed: 1966-04-28
Abstract: 1,129,565. Controlling reactors. SOCIETE D'ETUDE DE LA PROPULSION PAR REACTION, S.A. 28 April, 1966 [12 May, 1965], No. 18602/66. Heading G6C. A device for inserting an emergency control rod into a nuclear reactor comprises a telescopic assembly housing the control rod and being itself housed and guided within a cylindrical support fixed to the reactor superstructure in alignment with a duct provided in the interior of the reactor to receive the control rod, a chamber formed within the support and adapted to receive the combustion gases resulting from the explosion of an explosive cartridge within the device, the combustion gases causing the telescopic assembly to be extended and to propel the control rod towards the reactor interior, abutment means on the support and on the telescopic assembly for limiting movement of the latter within the support, and means for braking the control rod when it reaches its operative position in the duct. As shown in Figs. 1a, 1b, the telescopic assembly comprises outer and inner sleeves 9, 16, the former having its rear end enlarged to form a piston 10 which contacts the cylindrical support 1 and the latter having its rear end enlarged to form a piston 18 which contacts the outer sleeve 9. The inner sleeve 16 is fixed to a guide rod 7, on which a hollow control rod 6 is free to slide, and which extends into a duct 3 within the reactor core. A perforated guide member 8 is fixed to the front end of the guide rod 7. An explosive cartridge 24 is fixed to the rear end of the cylindrical support 1, a rear compartment of the inner sleeve 16 acting as an expansion chamber 25 for the combustion gases. End stops 13, 17 are provided on the front ends of the support 1 and outer sleeve 9 for the outer and inner sleeves, respectively. Resilient washers 15, 21 are provided on both sleeves for braking the sleeves and for forming a seal when movement has ceased. The annular space 19 between the two sleeves is connected by openings 20 near the front end of the outer sleeve with the annular space 12 between the outer sleeve and the cylindrical support which is, in turn, connected by openings 14 in the support with the atmosphere. The control rod 6 leaves the inner sleeve 16 directly this is stopped, sliding along the guide rod 7, a shoulder at the end of which enables the control rod to be decelerated at the end of its travel. The control rod is decelerated by means of brake discs or washers. In an alternative embodiment (not shown), the inner sleeve is fixed to but detachable from the front end of a propulsion device containing compressed CO 2 . The propulsion device is rigidly fixed to the cylindrical support and comprises a rear housing for an explosive cartridge and a chamber separated from the cartridge by a piston which fits closely and moves within this chamber. There is an annular V-groove where the propulsion device joins the inner sleeve. When the cartridge is fired, the piston compresses and heats the CO 2  until the inner sleeve separates from the gas bottle at the V-groove. The compressed CO 2  then drives both sleeves before it. The CO 2  is prevented by this means from liquefying as would occur in the course of a simple pressure-relief of CO 2  stored in the ambient conditions of the reactor.