GB968091A - Improvements in or relating to servicing machines for nuclear reactors - Google Patents

Abstract

968,091. Fuelling reactors. BRISTOL AEROJET Ltd. Dec. 15,1960 [Sept. 16,1959], No. 31560/59. Heading G6C. An arrangement for transferring fuel rods along a path between a reactor standpipe and a storage magazine of a servicing machine for the reactor comprising means for maintaining a flow of cooling gas past a fuel rod wherever in said path or magazine the fuel rod is disposed. The machine comprises a pressure vessel 1 containing a magazine 2 provided with an inner and an outer row of chambers 3 any one of which may be aligned with an opening 4 at the bottom of the vessel by rotation of the magazine about its own central axis and another eccentric axis. The magazine driving motions are derived from motors 115, 119 and are transmitted through Geneva stop mechanisms described with reference to Fig. 3 (not shown). A trunking assembly 8 extends downwardly from the opening 4 to the upper end 9 of the standpipe, this assembly including a valve 11 and pipes 12, 13, 16, an extension sleeve 17 of the pipe 16 being vertically movable by piston 18 so that it may seal with the standpipe end 9, the assembly also including the features disclosed in Specification 927,359. An annular space 34 is formed by upper and lower liners 19, 20 within the trunking assembly 8, the lower liner being axially movable and also rotatable whereby it may be coupled to a fuel element guide tube 26 of a charge shoot (Fig. 2) extending through the standpipe. The movements of the lines 20 imparted to the tube 26 cause the bottom section 26a of the charge shoot to be aligned with the desired reactor fuel element channel 48. The shoot is described more fully in Specification 968,092. An auxiliary pressure vessel 30 over the main vessel 1 houses a winch 27 controlling a cable 28 supporting a grab 29 so that the latter may be lowered through the magazine 2, opening 4 and liners 19, 20 into the charge shoot and thence into a channel 48. The grab is disclosed in Specification 931,408. In order to cool fuel elements withdrawn from the reactor hot coolant gas from the reactor passing up the annular space 34 leaves that space through a port 35 in the pipe 12 and enters a pipe 36 extending upwardly alongside the vessel 1. Where the pipe 36 passes the bottom of the vessel 1 a three-way value 37 is provided, the third way being connected by a passage 38 to the vessel 1. The upper part 36a of the pipe 36 is connected to the inlet of a heat exchanges 31, the cooled gas from the exchanger leaving through a pipe 40 and entering the vessel 1 through trunking 41 joining the vessel 1 to the vessel 30. The cooled gas flows downwardly through the chambers 3 and passes out through the opening 4, liners 19, 20 and guide tube 26 of the charge shoot. The gas is moved by a circulator 32. Another circulator 33 draws atmospheric air through the exchanger 31 to cool the gas. When the required operations have been carried out at a standpipe the valve 11 is closed and the valve 37 is rotated to close the pipe 36 and connect pipe 36a to the passage 38, the circulator 32 then driving the gas through a closed circuit including the magazine chambers. For use when loading new fuel elements into the reactor electrical heating elements are provided in the circulator 32 to preheat the fuel elements. The machine is mounted on wheels 43 and has gamma radiation shielding 45 and fast neutron shielding 46. A sleeve 49 on the charge shoot is lowered by a rod 51 to engage the end of the channel 48 when the tube 26a is aligned with the channel, and to permit the upward flow of coolant gas to be maintained through that channel a sleeve valve 52 is simultaneously operated to open ports 53, 54. The port 53 permits the cool gas which is being passed down the tube 26 to escape so that a flow is maintained through the magazine 2 while the port 54 allows the normal upward flow of gas through the channel 48 to continue.