IMPROVEMENTS IN AND RELATING TO STABILISING DEVICES FOR MEMBERS LOCATED IN BORES AND SUBJECT TO FLUID PRESSURE

摘要

1,208,613. Fuel elements. NUCLEAR POWER GROUP Ltd. 25 Oct., 1968 [8 Nov., 1967], No. 50890/67. Heading G6C. A fuel element string has a guide member 3 at its lower end and a brush-type seal 4 mounted in a recess in the member 3. The seal 4 may consist of metal fibres or wires embedded in a metal ring and must be capable of flexing in the manner of a brush so that it can deflect to pass any projection in the bore 1 of a graphite moderator core in which it is located. Although only one seal has been shown, two or more such seals may be spaced along the axial length of the fuel element string. Flexible membranes may be included between pairs of brush-type seals to improve the sealing properties. The fuel element string comprises graphite sleeves 2 which house fuel-containing members (not shown) and are spigotted together to form a flexible string which may be lowered into or withdrawn from the bore 1 in known manner whilst the reactor is on load. The seal helps to centralize the string in the bore and reduces the velocity of cooling fluid in the annular space between the sleeves 2 and the wall of the bore. As a result, vibrations set up by forces due to fluid pressure during insertion and withdrawal of the string are kept to a minimum.