GB1073557A - Improvements in and relating to the controlling systems for nuclear reactors - Google Patents

Abstract

1,073,557. Controlling reactwrs. SOC. ANGLO-BELGE VULCAIN, SOC. ANON. Aug. 12, 1965 [Aug. 19, 1964], No. 34515/65. Heading G6C. [Also in Division F2] A neutron-absorbing rod 1 is hydraulically actuated in a nuclear reactor by a system in which differential pressures in the primary fluid circuit of the reactor displace the rod in a guide tube 2 through which the primary fluid flows, this flow being controlled by a master valve 3 connecting one end of the guide tube 2 by means of tubes 4, 5 to one of two regions of the primary circuits in which prevail respectively a pressure lower than and a pressure higher than that prevailing at the other end of the tube. The primary fluid is a fluid effecting removal of heat from the core and/or its moderation and/or its temperature regulation. The master valve 3 is connected with a pilot valve 9 which controls the position of the slide of the master valve 3 in such a manner as to establish a variable orifice between the top of the tube 2 and either the tubing 4 or the tubing 5. The pilot valve 9 is itself connected with the primary circuit respectively upstream and downstream of the primary fluid circulating pump 12. The feeding of the pilot valve 9 is effected automatically or by hand by means of valves 13, 14. When it is desired to raise the rod 1 or to maintain it in a predetermined position in the tube 2, the pilot valve 9 is operated such that the slide of the master valve 3 is placed in a position for which an opening of predetermined size established communication between the top of the tube 2 and the tubing 4 connected to the lowpressure region of the primary circuit. When it is desired to introduce the rod into the core, the pilot valve 9 is operated such that the slide of the master valve 3 is placed in a position for which communication is established between the top of the tube 2 and the tubing 5 connected to the high pressure region of the primary circuit. The system is fail-safe because any absence of pressure for actuating the slide of the master valve (e.g. rupture of a conduit) involves its displacement to a position connecting the top of the tube 2 with the tubing 5 resulting in the rod being inserted into the core, and any absence of pressure of the primary fluid results in automatic introduction of the rod into the core under the action of gravity.