GB1351124A - Refuelling machines for nuclear reactors - Google Patents

Abstract

1351124 Fuelling reactors BRITISH NUCLEAR DESIGN & CONSTRUCTION Ltd 19 April 1971 [3 April 1970] 15914/70 Heading G6C A refuelling machine for handling reactor core material in the form of parallel columns, e.g. columns of moderator blocks including fuel elements, and adapted to operate through a standpipe which penetrates the reactor vessel, comprises a body member 10 adapted to be lowered into a standpipe 12, an indexing member 14 rotatable within the body member 10 about a first axis 16 and supported by a bearing 18 and guide rollers 20, and a refuelling arm member 22 rotatable within the indexing member 14 about a second axis 24. A rotatable skewer 30 formed at its lower end with means (not shown) which, on rotation of the skewer 30 by means of a drive system 32, is adapted to engage or disengage a co-operating reactor core column into which the skewer 30 may be inserted by lowering the member 22, is provided on the member 22. The refuelling arm member 22 and the body member 10 are interconnected by a pair of meshing gear-wheels 34, 36. A raise flower drive system 40 for the refuelling arm member 22 comprises a recirculating ball nut 38 attached to the top of a refuelling arm pivot tube 42 and engaging a drive shaft 44. Three level drives 46 (of which only one is shown) transmit power to the drive system 32, the raise/lower drive system 40, and a gear-wheel 48 provided on the indexing member 14. The body member 10 is lowered into the standpipe 12 via a magazine tube 50, one of a plurality in a rotatable magazine (not shown) similar in principle to the rotatable cartridge chamber employed in some firearms. In order to provide continued cooling during handling for columns containing fuel material, hot gas is permitted to escape from the reactor core through ports and ducts 56 to a heat exchanger from which cool gas is fed through ports and ducts 54 and a skewer hood 52 down through a column attached to the skewer 30. Operation of the bevel drive 46 associated with the gear-wheel 48 to cause rotation of the indexing member 14 will also cause rotation of the refuelling arm member 22 because of the interaction of the gear-wheels 34, 36. From the centre of the standpipe 12 the skewer 30 will pass in turn over the centres of a number of adjacent columns before returning to its starting position below the centre of the standpipe. The locus described by the skewer 30 is such that in moving a column from the standpipe to a vacancy in the core the rotational as well as the translational movement of the column is such as to orientate the column for lowering into the vacancy. The machine operator need therefore monitor and control only one parameter of movement, viz. the angular displacement of the indexing member 14 relative to the body member 10, in order to move a column radially out to a vacancy and to rotationally orientate the column with respect to the vacancy.