Patent GB-1282722-A (GB)
Title: Charge/discharge arrangements for nuclear reactors
Inventor: PUGH JOHN
IPC: G21C19/00
Filed: 1969-01-09
Abstract: 1282722 Fuelling reactors UNITED KINGDOM ATOMIC ENERGY AUTHORITY 2 Jan 1970 [9 Jan 1969] 1494/69 Heading G6C A gas-cooled reactor comprises a concrete pressure vessel 1 containing a core 2 and heat exchangers 3, the top cap of the pressure vessel having penetrations 9 and supporting a fuelling machine 20 movable on rails 21, 22. The machine 20 includes a pressurized container whereby fuelling may be performed whilst the reactor is operating by aligning the machine with a selected penetration 9. Core construction.-This comprises, Figs. 2, 3, columns formed by superimposed moderator blocks 6 of pentagonal cross-section, the blocks having coolant holes 6a supporting annular fuel bodies 6b and a central hole x for receiving a lifting rod. Certain corners of the blocks 6 are formed with arcuate surfaces forming holes q, p for receiving a plug 8 or a guide sleeve 7 for a control rod. Four adjacent columns form a group centred about a plug 8, the plugs 8 and sleeves 7 being arranged on square lattices and the plug holes q being in alignment with the penetrations 9. Each plug 8 serves to force the four columns of its group away from each other, thereby providing clearances C, the other surfaces, y, of the columns being forced against surfaces z of columns of adjacent groups. The clearances C provide a working clearance to facilitate removal or replacement of the blocks 6 after previous removal of the associated plug 8. Fuelling machine 20.-This includes a fuel block handling assembly 30, Fig. 4, which may be lowered through a penetration 9 into the plenum 5. The lower end of the assembly comprises a tube 31 slotted along one side so that a fuel block lifting rod 32 may be moved laterally through the slot by a bell-crank lever system 56. For removal of a plug 8, a plug lifting rod assembly 29 is coupled to the rod 32. The assembly 30 is described in greater detail with reference to Fig. 5 (not shown), and the assembly 29 with reference to Figs. 6, 7 (not shown). Fuelling operation.-The appropriate plug 8 is withdrawn by the assembly 29, shown at (a) in Fig. 4, and lifted out of the corehole q. The assembly 29 is disconnected from assembly 30 and the rod 32 is aligned with the hole x of the block 6 at the top of one of the associated columns, shown at (b), Fig. 4. The assembly 30 is lowered so that the fingers at the lower end of the rod 32 may engage a surface at the lower end of the second block 6 from the top of the column. The tube 31 similarly penetrates the top of the hole q vacated by the plug 8 to act as a keeper tube and steady the adjacent columns of blocks. The assembly 30 is raised so that when the rod 32 returns to the plenum 5 the rod may be retracted into the tube 31 and the two blocks 6 removed by the rod 32 may be raised through the penetration 9, see (c), Fig. 4. This process is repeated until the bottom two blocks 6 of the column are removed, see (d), Fig. 4. In a modification (Figs. 8, 9, not shown), the keeper tube is a separate component inserted by the machine 20 and is not part of the assembly 30.