GB828055A - Improvements in or relating to nuclear reactor units - Google Patents

Abstract

828,055. Nuclear reactors. ROLLS-ROYCE Ltd. July 9, 1956 [Aug. 17, 1955], No. 23755/55. Class 39(4). A nuclear reactor comprises a core provided with a plurality of fuel-rod receiving bores whereof the axes meet at a point outside the reactor core on the side thereof from which the fuel rods are manipulated for insertion and removal from the core. The reactor shown in Fig. 1 comprises a casing 10 of conical form housing at its upper end a reactor core 12 of carbon or beryllium bricks separated by a heavy steel plate 13 from a lower space which accommodates a fuel rod handling mechanism. The casing 10 is filled with liquid sodium and is provided with inlet and outlet pipes 16, 17. The fuel rod manipulating mechanism comprises a pair of telescoping members 18, 19 ; the lower member 18 is provided with a universal mounting and can be driven in two directions by electrical actuators 23, 25. The member 18 is surrounded by a bellows 26 and the joint between members 18 and 19 is sealed by a further bellows 31. The member 19 is provided with two bores which are connected to pressure or suction sources by flexible pipes 29, 30. Each fuel rod 35, Fig. 3, is fitted at its upper end with a cap 36 having a central spherical depression and at its lower end is provided with a part-spherical portion 37 formed with a number of peripheral recesses and a central axial recess. The fuel rod is housed in a metal canister 38 to the bottom of which is clamped a spring 40, the other end of which is clamped to a plug 41. A rod 42 secured to the plug 41 has a flanged end and serves to limit the downward travel of plug 41 reletive to the canister 38. Prior to charging a fuel rod into the reactor, the rod and its canister are placed in a charging container 43 of cylindrical form having an open side through which a canister can pass. The upper end of the container is provided with a spring-loaded disc 43c, and the container is provided with plugs 44, 45 at each end. Referring back to Fig. 1, the reactor is provided with a side chamber 15 which has an inlet and an outlet formed by dies 46, 49 and sockets 47, 50 into which are fitted receivers 48, 51 for fresh and used fuel rods assemblies respectively. In Fig. 1 a spent fuel rod assembly is shown at A, and a fresh one at B. The assembly B is pushed by a ram into the position of assembly A which is discharged into the receiver 51 ; during this operation the plugs 44, 45 are reduced in diameter in passing through the dies 46, 49 and so a seal is maintained to prevent leakage of radio-active sodium from the chamber 15. A pair of ram pistons push the fresh canister out of its container and moves it to the edge of the chamber 15 where it is received by the telescopic member 19 and transferred into one of the fuel channels. Referring to Fig. 5 the canister 38 is pushed into the fuel channel by member 19 until the spring 40 snaps into a groove in the plate 13. The fuel rod is then withdrawn into a narrower part 33 of the fuel channel by means of a control probe 60 which is provided with a spherical end, which fits into the spherical depression in the fuel rod, and with a longitudinal bore to which suction is applied. To unload a rod, the operations described are reversed. 'Specification 828,054 is referred to.