GB934222A - Improvements relating to grab devices - Google Patents

Abstract

934,222. Servicing reactors. UNITED KINGDOM ATOMIC ENERGY AUTHORITY. Dec. 29, 1961 [Jan. 5, 1961], No. 504/61. Class 39 (4). A grab for servicing a reactor in the manner disclosed in Specification 934,221, in which a fuel element is extracted from the reactor core by a grab and placed in a liquid-filled carrier adjacent the core, the carrier then being removed from the reactor by the grab, comprises a tubular housing 11 having longitudinal slots 13 accommodating two sets 14a, 14b and 15a, 15b of claw plates. The plates have outwardly-directed hooks at their lower ends so that when these hooks are moved outwardly by rotation of the plates about pivots 16, 17 the hooks may engage beneath internal recesses formed in the open tubular end of the part to be lifted. The claw plates 14a, 14b serve for lifting a fuel element and have hooks which are moved outwardly to a lesser extent than the hooks of plates 15a, 15b which serve for lifting the carrier. The claw plates are operated by a longitudinal actuating member 20 having, for each plate, three cam tracks 21, 22, 23 cooperating with projections 18, 19 on the plates. The arrangement is such that the claw plates are at all times positively held by engagement between the projections and cam tracks. To lift a fuel element the grab is lowered until contact is made with a stop 24 on the housing 11 whereupon the actuating member 20 is raised so that projections 19 of the plates 14a, 14b leave the cam tracks 23 and move on to the tracks 22 and projections 18 move from the tracks 21 to the tracks 23, thereby pivoting the hooks outwardly to engage the fuel element. The grab then lowers the fuel element into the carrier until the carrier is engaged by a stop 25 whereupon the member 20 is raised through a further extent so that the projections 19 on the plates 15a, 15b engage the cam tracks 22 and projections 18 engage the tracks 23 and thus the hooks on the plates are moved outwardly to engage the carrier. Hence when the grab is subsequently raised both the fuel element and the carrier are independently lifted by their respective hooks.