Patent GB-942277-A (GB)
Title: Nuclear reactor fuel element changing arrangements
IPC: G21C1/18
Filed: 1961-01-30
Abstract: 942,277. Fuelling reactors. SULZER FRERES S. A. Jan. 30, 1961 [Feb. 12, 1960], No. 3536/61. Heading G6C. A reactor, Fig. 1, comprises a core 1 having a number of channels (only one shown) in which fuel.elements 2 are retained by a disengageable connection head 3, each head including a coupling for supporting a fuel element and also connections for a pair of pipes 4 connected to headers 5. Each pair of pipes 4 provides an inlet and outlet for a coolant flow path provided within each fuel element, the headers 5 being connected to heat exchangers. A handling device 8 movable along a gantry 7 pivoted at 9 permits a selected head 3 to be disengaged. A pair of rotatable screening members 12,13 are mounted beneath the core 1, an eccentric aperture 14 in the eccentrically-mounted member 12 being positioned beneath that fuel element 2 which it is desired to remove. A refuelling apparatus 17 having a cab 18 and magazine 25 has two sets of wheels 20, 21 whereby it may be moved in two directions mutually at right angles to align the magazine with the aperture 14. The magazine has two compartments one of which initially contains a new fuel element and both of which contain a lifting mechanism. The magazine can also be rotated about a horizontal axis 24 to be brought into alignment with an aperture 32. A pivoted tube 29 containing a gripper 30 supported by a rope 30a may be aligned with the aperture 32 and may also be swung into alignment with a passage 34 leading to a water-filled storage chamber 33. To change a fuel element 2 the pipes 4 associated with that element are closed, the lifting mechanism associated with the empty magazine compartment is raised to the support the fuel element and the connection head 3 of that element is disengaged by the device 8. The lifting mechanism is now lowered so that the spent fuel element is received in the magazine 25 and the magazine rotated so that the new fuel element in the other compartment may be lifted into the core 1 where it is retained by re-engaging the head 3. The magazine is now aligned with the aperture 32 and the spent fuel element is drawn into the tube 29 by the gripper 30 and then lowered through the passage 34 on to a conveyer 36 in the chamber 33, a crane 37 conveying the element 2 to a storage apparatus 38. A new fuel element travels over this path but in the reverse direction. A connection head 3, Fig. 3, comprises a retaining member 44 having projections 45 complementary to projections 42 on the fuel element, this member being rotatably connected to a support bracket 54 by a pin 56, a square end 57 on the member 44 being engageable by the device 8 to be rotated thereby and cause disengagement of the projections 42, 45 and permit release of the fuel element. The fuel element has a coolant entry passage formed by the annular space surrounding an inner tube 43, this tube forming the coolant exit passage, these passages being connected to pipes 47, 48 corresponding to the pipes 4 of Fig. 1. A tubular portion 49 of the bracket 54 makes connection with the tube 43 and an outer tubular portion of the bracket has an annular recess 50 accommodating a seal which may be inflated by a pressure medium supplied through a pipe 52, this pressure being reduced prior to rotating the member 44 to effect disconnection. In a modified head 3 (Fig. 6, not shown) the device 8 is not required, the disconnection and connection of the fuel element being obtained by applying a pressure medium to a bellows embodied in the head. In a modified arrangement (Fig. 4, not shown) the handling device for the heads 3 is mounted on one of a pair of relatively rotatable cover plates situated above the reactor and the refuelling apparatus is carried by the member 12. In this arrangement the control rods may be replaced similarly to the fuel elements. In a further modification (Fig. 5, not shown) the magazine is not tiltable about a horizontal axis, the spent fuel element being withdrawn therefrom into a vertical passage and subsequently lowered from this passage into the chamber 33.