GB948233A - A device for anchoring and extracting plugs in and from fuel channels of nuclear reactors - Google Patents

Abstract

948,233. Stud and socket fastenings. COMMISSARIAT A L'ENERGIE ATOMIQUE. Aug. 14, 1962 [Aug. 16, 1961], No. 31209/62. Heading E2B. [Also in Divisions F2 and G6] The invention provides a plug and inserter for nuclear reactor fuel channels which can be locked in position therein by pawls which are themselves locked, and includes provision for ensuring that the plug is locked before the plug inserting device is withdrawn. The fuel channel tube 13 includes an annular recess 85 and a seating shoulder 99a. The plug comprises a body 11, a locking member 121 urged upwardly by a spring 129, and three or more locking pawls 120 pivotably mounted in the plug portion 126 within grooves 134 therein. The inserter comprises a guide and sealing tube 47 within which is situated a handling clamp 122 having grab levers 123 and a grab lever actuating rod 131 axially movable within and independently of the handling clamp 122. In its inserted position (Fig. 1), the plug rests on the channel tube shoulder 99a, and is retained in this position by the pawls 120 engaging the channel tube recess 85; sealing is provided by the members 103. To unlock and remove the plug, the sealing tube 47 is positioned on the channel tube end as shown, and the handling clamp 122 lowered until its grab levers 123 abut a shoulder 126 in the top of the plug. The actuating rod is moved upwardly, which causes its annular portion 131a to contact the upper end of the grab levers 123 outwardly and thereby engages shoulders 125 within an annular recess 127 in the locking member 121. The handling clamp and actuating rod are moved simultaneously downward until the projection 124 is situated below the shoulder 126; since the shoulder 125 is engaged in the recess 127, the locking member 121 will have been pushed down, thus unlocking the pawls 120. The position now reached is shown in Fig. 3. The actuating rod is moved downward, thus causing the lower annular portion 131a to move the grab levers 123 outwards to the position shown in Fig. 4, in which they hold the pawls out of engagement with the recess 85, and still restrain the locking member 121 from moving upwards. The plug can now be withdrawn by raising the handling clamp 122. Insertion of the plug follows the above procedure in reverse, and it is to be noted that during insertion of the plug, it is impossible to disconnect the handling clamp unless the pawls have correctly engaged in the channel tube recess.