GB808381A - Improvements in nuclear reactor fuel element handling plant - Google Patents

Abstract

808,381. Handling materials in radioactive environment. BABCOCK & WILCOX Ltd. Feb. 12, 1957 [Feb. 13, 1956], No. 4453/56. Class 39(4). Spent rod-like fuel elements withdrawn by a loading machine 5 through the top 3 of a reactor 1 are conveyed by a biological protection shoot 12 and carriage 72 to the bottom of a pond 60. The shoot has a curved portion 12C to frictionally retard each fuel element so that it would come to rest in the horizontal portion 12D ; however, water jets, Fig. 5 (not shown) in the portion 12D drive the element into a discharge chamber 13 where it is arrested by a horizontally-movable buffer 35 and drops into a recess 26. A plate 27 pivoted at 28 normally closes the bottom of the recess by a counterweight 29 but is moved to the position shown in which a nozzle 31 permits passage of the fuel element into a skip 73 on the carriage 72 when the skip engages a cam 84 on the plate 27. The carriage is traversed on an inclined track 71 by a winch motor 77 and the skip is removed from the carriage when in its lowest position by the lifting tackle 93 of a transporter crane 90. The motor 77 is remotely controlled for lowering the carriage 72 by a control in the control cabin of the loading machine 5 and for raising the carriage by a control in the crane 90. Warning light indicators in the cabins of the loading machine and crane are operated automatically by the passage of the carriage on the track 71 and by the removal of a loaded skip by the crane thereby ensuring that fuel elements are not released into the top of the shoot 12 except when an empty skip 73 is beneath the chamber 13. Further, lights on a mimic diagram of the shoot in the loading machine cabin indicate the passage of each element along the shoot. In the event of breakdown of the carriage 72 or crane 90 the fuel elements may be jettisoned through the end of the chamber 13 by vertically raising an emergency door 40 carrying the buffer 35, the door having a nut member 47 engaged by a threaded rod 45 which is rotated for this purpose. Should an element jam in the shoot it may be dislodged by opening valves controlling further water jets 22. Additional jets 120 acting upwardly in the shoot may provide an increased retardation of the elements.