GB854764A - Improvements relating to nuclear reactor charging apparatus - Google Patents

Abstract

854,764. Nuclear reactors; handling nuclear fuel elements. A.E.I.-J. THOMPSON NUCLEAR ENERGY CO. Ltd. Feb. 13, 1958 [Feb. 27, 1957], No. 6586/57. Class 39(4). An arrangement for loading or unloading the vertical fuel element channels in the graphite core of a gas-cooled reactor whilst the reactor is operative comprises positioning a shoot charging apparatus above a selected fuel element charging standpipe by means of which a biological shielding plug in the mouth of the standpipe is removed and a shoot inserted into the standpipe and then removing the shoot charging apparatus and replacing it by a fuel element charging or discharging apparatus by means of which biological shielding plugs in the mouth of the shoot are removed and the fuel elements loaded or unloaded. As shown in Fig. 1 a standpipe 4 extends through the pressure vessel 1 and a biological shield 2, the charging floor 3, permitting movement of the shoot charging apparatus 9, Fig. 5, and the fuel element charging apparatus 19, Fig. 6. The mouth of the standpipe 4 is closed by a concrete plug 5, Fig. 2, having a bar 7 whereby it may be lifted. The shoot charging apparatus 9 comprises storage passages 10, 11 rotatable about a vertical axis and upper and lower shielding parts 18, 17, and is temporarily sealed to the standpipe by a flexible gas-tight coupling 29. A grab within the apparatus 9, Fig. 7 (not shown), and similar to that disclosed in Specification 846,923 permits removal of the plug 5 into the passage 10 as shown in Fig. 5 and then after rotation of the passages 10, 11, enables a shoot 12 to be lowered from the passage 11 into the standpipe 4. When the apparatus 9 is removed the part 17 is left behind and the fuel element charging apparatus 19 placed thereupon. The apparatus 19 contains a grab 23 similar to that mentioned above and a fuel element magazine 20 having a number of fuel element compartments 21 arranged around its periphery. The grab 23 first removes concrete plugs 13 . . . 16 from the mouth of the shoot 12 and stores them temporarily in the magazine and then loads or unloads fuel elements, the magazine 20 being moved by a Geneva mechanism, Fig. 7 (not shown), to align successive compartments 21 with the standpipe 4. Each fuel element 42, Fig. 10, is supported in a rectangular carrier 41 having a top bar 43 for engagement by the grab. The fuel elements normally rest on latches Figs. 12-14 (not shown), in the compartments 21 but the latch of that compartment in alignment with the standpipe 4 is released to permit the lowering of the grab and fuel element into the reactor. The extent of the hoisting movement of the grab is determined by limit switches and these limits are varied in accordance with the vertical position of the fuel element in the core ; further, a deceleration switch causes the deceleration of the hoisting movement to be successively advanced or retarded depending on whether the stack of fuel elements in a core channel is being built up or removed. Specifications 826,870 and 843,830 are referred to.