GB840332A - Improvements relating to nuclear reactors - Google Patents

Abstract

840,332. Nuclear reactors. A.E.I.-J. THOMPSON NUCLEAR ENERGY CO. Ltd. March 13, 1958 [March 21, 1957], No. 9311/57. Class 39(4). A coolant flow restrictor for use in a coolant channel in the core of a fluid cooled nuclear reactor, of the type having a plurality of vertical channels through which the coolant flows upwards, comprises an outer fixed member adapted to be attached to the wall of the channel and having a longitudinally extending duct therein, an inner removable member located partly within the duct in the outer member, and an annular path for the passage of coolant extending along the duct and longitudinally between the two members, the annular path being formed with a lower stage having a cross-sectional area which is progressively reduced in the direction of coolant flow followed by a stage having a substantially constant crosssectional area. The arrangement is designed to minimise the force exerted by the coolant on the removable part of the gag. In Fig. 2, the coolant flow is restricted by a nozzle 2 which carries a support 3 for the removable part 4 of the gag. At the lower end of 4 above the point where it is supported by 3 there is a conical portion 7. In a modification of this, Fig. 3 (not shown), the conical portion 7 is surmounted by an inverted conical portion. In another arrangement, Fig. 4 (not shown), member 2 is cylindrical and member 4 is bullet-shaped. Fig. 5 shows a gag for use in fuel channels which are provided with two longitudinal slots 23, 24 in an otherwise cylindrical channel. The fixed member 25 is secured to the reactor core by a flange. The removable member comprises a thin plate 34 which extends across the channel and has thicker edges which engage the slots 23, 24; a cylindrical part 37 has projections which extend on either side of plate 34 and are bolted to it.