Patent Number: 040509877
Section: description

DESCRIPTION OF THE PREFERRED EMBODIMENT Throughout the description which follows, like reference characters indicate like elements of various figures of the drawings. FIG. 1 of the drawing illustrates a typical nuclear reactor system which can employ the principles of this invention. An elongated nuclear reactor pressure vessel 10 contains a quantity of reactor coolant such as liquid sodium graphically illustrated and designated as the Numeral 12. The top of the pressure vessel 10 is sealed by a nuclear reactor pressure vessel closure head 14. In the space formed by the pressure vessel 10 and the closure head 14 and above the level of liquid coolant 12 is installed an inert gas known generally as cover gas 16. The head 14 has a stationary outer ring 18 which is bolted to a flange 20 of the pressure vessel 10. The head 14 has a plurality of generally planar, cylindrical rotating members such as plugs 22, 24 and 26. The plug 22, of the largest diameter, is coaxial with the vessel 10. The stationary member, ring 18, has an opening 19 in which the large plug 22 is positioned. The large plug 22 has an opening 23, excentric to the large plug axis 37 in which the intermediate plug 24 is positioned. The intermediate plug 24 has an opening 25, excentric to the intermediate plug axis 39 in which the small plug 26 is positioned. These rotating plugs 22, 24, 26 position the fuel and control handling equipment over all desired vessel locations. The plug 26 supports an in-vessel transfer machine plug 28 excentrically. The plug 22 supports the ex-vessel transfer machine plug 30 excentrically. The plug 24 supports columns 32 which support the upper internals (not shown), the control rod assembly mechanisms 34, and one or more sealed surveillance ports 36. By rotating the plugs 22, 24, 26, the in-vessel transfer machine plug 28 can be positioned over the various components in the vessel, and over the ex-vessel transfer machine plug 30. The small plug 26 is connected to and supported by plug 24 through the load structure 42. The intermediate plug 24 is connected to and supported by plug 22 through the load structure 40. The large plug 22 is connected to and supported by the stationary outer ring 18 through the load structure 38. FIG. 2, a top view of the closure head 14, illustrates the rotation of these plugs 22, 24 and 26. The smallest diameter plug 26 can rotate about its axis 41. The intermediate plug 24 can rotate around its axis 39 and the small plug 26 remains in its position on plug 24. The large plug 22 can rotate around its axis 37 while both plugs 24 and 26 remain in their position on plug 22. In this manner, the small plug 26 and its in-vessel transfer machine plug 28 can be positioned over any desired vessel locations. Reference is now made to FIG. 3, which shows a detailed view of the load structure 38 between the stationary outer ring 18 and the largest diameter plug 22. This load structure 38 is illustrated for descriptive purposes, and it would be obvious to one skilled in the art that a similar structure may be employed as load structures 40 and 42. Likewise, the asimilar structure may be used in conjunction with any rotating member which penetrates the closure head 14. The stationary ring 18 has an annular supporting structure 44 rising vertically above the top edge 46 of the stationary ring 18. The supporting structure 44 is connected to the inner race 48 of the bearing 50. The inner race 48 and its associated bearing 50 are secured to the supporting structure 44 by means of a ring 52. The inner side 54 of the annular supporting structure 44, contains cavities 56 into which maintenance seals (not shown) can be inserted during maintenance operations. The large plug 22 has an annular support riser 58 rising vertically above the top edge 60 of the large ring 22. The support riser 58 has an extension 59 comprised of an upper flange 62 which fits over the top side 64 of the supporting member 44 of the stationary ring 18, and an annular sealing structure 66 which is hermetically secured to the flange 62 of the support riser 58 and extends vertically downward from the upper flange 62 adjacent to the outer side 68 of the supporting structure 44. The support riser 58 and the extension 59 form a generally U-shaped first annular space 63 in which the support structure 44 is positioned. The outer side 68 of the supporting structure 44 and the edge 70 of the sealing structure 66 (part of the extension 59) form a second annular space 84. Three elements, the support riser 58, the upper flange 62, and the sealing structure 66 form the support structure 61 of the large plug 22. While support structure 61 can be manufactured as one piece, for ease of installation and maintenance the preferred method is to use the three separate elements 58, 62, and 66. Throughout the following description, it will be assumed that the support structure 61 is comprised of the three elements 58, 62 and 66, although the invention is equally applicable to a one-piece structure. The edge 70 of the sealing structure 66 has cavities 72 above the elevation of the bearing 50 into which sealing means such as inflatable annular seals 74 are placed. Lubricating means 76 are connected on one side to the inflatable seals 74, and are accessible to the exterior 78 of the sealing structure 66. The sealing structure 66 is secured to, and supported by, the outer race 80 of the bearing 50. A lubricant collector 82 is located beneath the bearing 50, the inner race 48 and the outer race 80. This lubricant collector 82 is shown in the drawing as being connected to outer race 80, although alternate locations would have it connected to the inner race 48 or the support structure 44. During rotation of the plug 22, the support structure 61, shown as support riser 58 flange 62, and sealing structure 66, the outer race 80, the seals 74 and the lubricant collector 82, if so connected, rotate around the large plug axis 37. The stationary ring 18 with its supporting structure 44, the inner race 48, and the ring 52 remain stationary. The plug 22 is supported above the reactor vessel 10 during this rotation by the stationary ring 18 through the bearing 50. During lubrication, lubricant is inserted through the lubricating means 76 to the seals 74. The lubricant then flows down the annulur space 84 between the external edge 68 of the supporting structure 44 and the edge 70 of the sealing structure 66 to the bearing 50. Any excess lubrication is then caught in the lubricant collector 82. If the lubricant collector 82 becomes full, the lubricant could be removed by means of a drain hole (not shown). Although not shown on the drawing, if means for lubricating the bearing 50 directly are desired, such means can be inserted through the outer race 80. Any excess lubricant from this lubrication would also be caught in the lubricant collector 82. During maintenance operations, maintenance seals (not shown) are inserted into the cavities 56 provided for them in the supporting structure 44 of the stationary ring 18. These seals prevent the escape of any gases from the reactor cavity 16. Then the sealing structure 66 and the bearing 50 are removed from their positions. The seals 74 and the bearing 50 can then be replaced. Thus, it can be seen that this invention teaches a system by which seals and bearings for rotating members above the reactor vessel of nuclear reactors can be lubricated without risk of having lubricant drain into the reactor vessel.