Improvements in machines for loading and unloading the channels of a nuclear reactor

941,600. Handling devices for use in nuclear reactors. COMMISSARIAT A L'ENERGIE ATOMIQUE. July 26,1962 [Aug. 16, 1961], No. 28840/62. Heading G6C. A machine for loading elements of large and small diameter into the fuel channels of a nuclear reactor whose channels each comprise a central portion of a relatively small diameter and at least one outer portion of relatively large diameter opening into the reactor loading base, said machine comprising a tube of an external diameter to fit the outer channel portions and of internal diameter equal to the small channel diameter, said tube being axially slidable in a passage of said machine from a position within said passage to a position within the outer channel portion, a rod of a size to be slidable within the tube and central fuel channel portion, grapple means on the ends of both the tube and the rod, and means for moving said rod and. -tube with respect to said passage, and said rod with respect to said tube. The elements referred to are fuel elements and dummy fuel elements to be fitted in the small diameter portion of the channels, and shielding slugs and closure plugs to fit the large diameter channel portion. Machine details. Referring to Fig. 1, the grapple tube passage comprises a tube 15 and a bore 60 in a magazine 61 rotated by a motor 58. The grapple tube passage is surrounded by lead or concrete shielding 14 situated adjacent the reactor end face 12 on which can be seen the fuel channel end caps 13. One such fuel channel is shown in section and comprises a large diameter outer portion 2 containing plug 11 and a shielding slug 10, and a small diameter inner portion 1 containing dummy fuel elements 9 for shielding and fuel elements 8. The larger diameter is 1.3 to 1.5 times the smaller diameter. Coolant passes along the fuel channel and leaves it through an outlet conduit 4. At the end of the charging machine remote from the reactor is a housing containing a winch 29 having a pair of drums, a winch motor 30, and a hydraulic inlet 32. The hydraulic fluid is used for driving the grapple rod and tube forward and is preferably identical to the reactor cooling fluid although at a higher pressure. Provision may be made for controlled leakage of this fluid from the grapple tube passage (e.g. through 39, Fig. 5) and then into the reactor fuel element channel in order to cool the grapple actuating mechanism. With reference to Fig. 4, the grapple tube passage is extended from a flange on the magazine casing 61