GB890523A - Improvements in nuclear reactors - Google Patents

Abstract

890,523. Nuclear reactors. BABCOCK & WILCOX Ltd. July 13, 1960 [July 13, 1959], No. 23953/59. Class 39(4) In a nuclear reactor having a restraint garter surrounding a stack of material providing the moderator of the reactor core, the garter includes fluid pressure responsive biasing means adapted when subjected to the pressure of fluid under super-atmospheric pressure supplied as coolant to the core to exert a force acting through the garter on the stack to restrain the material of the stack. Fig. 3 shows a plan view of part of the restraint means which include a number of channel-shaped stays 6 mounted in a groove in the moderator block 1, each stay 6 being provided with a central vertical rib 9 located in a recess in the groove. Adjacent stays 6 are coupled together by a pair of balance beams, of which the upper one 13 is shown, pivoted to the upper and lower plates of the stays 6 by pivot pins 15 passing through elongated holes in the balance beams. A pivot pin 21 passing through the balance beams carries a mild steel link 24 which extends to a pivot pin 22 which passes through elongated holes in the balance beams to allow the inner end of link 24 to rock a few degrees about pin 21. Pivoted to pin 22 are the ends of two link plates 26 (of which only the upper one is shown) connected by a pintle 29 to a lug 31 of a stainless steel bellows unit 32 filled with helium at a pressure of about ¢ 1b. per square inch absolute. The other end of the bellows unit is provided with a threaded stud screwed into one end of a mild steel tube 30 which extends centrally through the channel in stay 6 and forms part of a ring of linkwork encircling the core. The other end of each tube 30 is screwed to a threaded shank attached to a clevis pivoted to a pin 22, the two screw threads being of opposite sense to enable the initial tension of the linkwork to be adjusted by rotating the tubes 30. In operation the pressure within the reactor increases the differential pressure on bellows 32 and thus increases the tension in the garter to offset the effect of the pressure of the coolant gas in the cooling channels. In another arrangement. Fig. 6 (not shown), the tie rods 30 extend between pins 22 and the bellows replace the link 24. Specification 890,520 is referred to.