Patent Number: 047073233
Section: claims

1. A closure for an inclined duct having an open upper end and defining a downwardly extending passageway comprising: cap means for sealing engagement with said open upper end of said duct;  an array of vertically aligned plug members each having a cross-sectional area substantially conforming to the cross-sectional area of said passageway at least adjacent an upper end thereof and being freely movable therein, each of said plug members comprising a cylinder each cylinder having a longitudinally-extending axle at each end;  means interconnecting each of said vertically aligned plug members, said means providing for free movement of said plug members only in the plane in which said duct is inclined, said means comprising a plurality of end plates interconnecting axles of adjacent cylinders;  means connecting said cap means to the uppermost plug of said array and;  hoist means located directly over the open upper end of said duct for moving said closure between an upper position at which said lowermost plug of said array is above the open upper end of said duct and a lower position at which said cap means is in engagement with the open upper end of said duct.  cap means for sealing engagement with said open upper end of said duct;  an array of vertically aligned plug members each having a substantially rectangular cross-sectional area conforming to the cross-sectional area of the passageway, at least adjacent an upper end thereof and being freely movable therein, each of said plug members comprising a cylinder, each cylinder having a longitudinally extending axle at each end;  means interconnecting each of said vertically aligned plug members, said means providing for free movement of said plug members only in the plane in which said duct is inclined, said means comprising a plurality of end plates interconnecting axles of adjacent cylinders;  means connecting said cap means to the uppermost plug of said array;  hoist means located directly over the upper end of said duct for moving said closure between an upper position at which said lowermost plug of said array is above the open upper end of said duct, and a lower position at which said cap means is in engagement with the open upper end of said duct; and  means associated with said cap means for guiding at least a lower portion of said array of said vertically aligned plug members into the open upper end of said duct. 2. The closure of claim 1 further including latch means associated with said cap means for securing said cap means to the open upper end of said duct. 3. The closure of claim 2 wherein said latch means is attached to said cap means and connected to said hoist means for engaging said latch means when said cap means engages the open end of said duct and for releasing said latch means when said hoist means moves in an upward direction. 4. The closure of claim 1 further including means for guiding at least a lower portion of said array of vertically aligned plug members into the open upper end of said duct. 5. The closure of claim 4 wherein said guide means comprises a vertical member in fixed relation to said duct means and said cap means includes an alignment member in vertically slideable engagement with said vertical member. 6. The closure of claim 5 wherein said vertical member has a lower terminal end located above the open end of said duct. 7. The closure of claim 1 wherein said plug members adjacent a lower portion of said array comprise thermal insulators. 8. The closure of claim 1 wherein said duct is a fuel transfer duct in a nuclear reactor. 9. In a liquid metal cooled fast breeder reactor, a closure for an inclined fuel transfer duct, said duct having an open upper end and defining a downwardly extending substantially rectangular passageway comprising: 10. The closure of claim 9 further including latch means associated with said cap means for securing said cap means to the open end of said duct. 11. The closure of claim 10 wherein said guide means comprises a vertical member in fixed relation to said duct means and said cap means includes an alignment member in vertically slideable engagement with said vertical member. 12. The closure of claim 11 wherein said vertical member has a lower terminal end located at a higher elevation than the open end of said duct. 13. The closure of claim 12 wherein said latch means is attached to to said cap means and connected to said hoist means for engaging said latch means when said cap means engages the open end of said duct, and for releasing said latch means when said hoist means moves in an upward direction.