Patent Number: 053848128
Section: description

DETAILED DESCRIPTION OF THE INVENTION Referring now to the figures, wherein similar structures common to each figure will be referenced by the same reference numbers throughout this specification for simplicity of exposition, a cabling arrangement of the present invention for a nuclear reactor vessel is illustrated in three different positions in FIGS. 1-3. Nuclear reactor vessel 1 is located within a containment (not shown). A structural wall 5 within the containment spaced from reactor vessel 1 and extending to about the elevation of an IHP 7 sealed to the top of reactor vessel 1 at flange 8 defines a cavity 9 that is filled with water during refueling of the reactor. IHP 7 consists of a reactor vessel head 11, control rod drive mechanisms (CRDM's) (not shown), control rod position indicators (RPI's) (not shown), cooling fans 13 and other associated hardware. An operating deck 15, typically supported by wall 5 and located outside cavity 9 distal from reactor vessel 1, separates a sub--space 17 below deck 15 on a far side 19 of wall 5 from an operating area 21 above deck 15. Power, control and other electrical cables 23 to the CRDM's or RPI's are run from connector plates 25, 27 mounted on IHP 7 where cables 23 are connected at their first ends 29, through an opening 31 in deck 15, and then to control panels 33 located in sub-space 17 where cables 23 are connected at their second ends 35 (FIG. 1). Cavity 9 is typically filled with water during refueling of reactor vessel 1 when reactor vessel head 11 is removed. Prior to refueling, first ends 29 of all cables 23 must be disconnected from IHP 7 and removed from the area around cavity 9, and preferably removed into sub-space 17 (FIG. 3). A movable frame 41 is provided to facilitate removal of cables 23 from an area around reactor vessel 1 and from operating area 21 before refueling, and also to facilitate reconnection of cables 23 to IHP 7 after refueling and before start-up of the reactor. Frame 41 supports a length of each cable extending through frame 41, and is movable, with cables 23, between a first position 43 outside sub-space 17 proximate head package 7 (FIG. 1) and a second position 45 in sub-space 17 (FIG. 3). Frame 41 in first position 43 is oriented generally horizontally and straddles a top 47 of wall 5. In second position 45, frame 41 is oriented about vertically proximate far side 19 of wall 5. A pivot arrangement 49 near a first end 51 of frame 41 distal from reactor vessel 1 and overhanging sub-space 17 permits frame 41 to pivot between first position 43 and a substantially vertically oriented intermediate position 53 (FIG. 2). Frame 41 can be moved between first position 43 and intermediate position 53 by any of a variety of mechanisms known in the mechanical arts. For example, frame 41 can be hoisted and lowered with removable cables 54 attached to an electrically powered overhead winch (not shown). Frame 41, while vertically oriented, is guided through opening 31 along a predetermined path between intermediate position 53 and second position 45 by a guide mechanism 55. Guide mechanism 55 can include, preferably, a track 57 fixed in an about vertical orientation proximate distal side 19 of wall 5 and means 58 located near first end 51 of frame 41 engaging track 57 such that movement of frame 41 is restricted to the predetermined path parallel to track 57 between the intermediate position 53 and second position 45. Frame 41 can be raised and lowered into sub-space 17 by the same mechanism that moves frame 41 between first position 43 and second position 45, or guide mechanism 55 can further include a separate motive system 59 operably connected to the frame for providing a motive force for lifting, or lifting and lowering, the frame between second position 45 and intermediate position 53. The motive system can be powered by any number of standard modes of powering lift systems, such as, for example, electric motors, hydraulics, and pneumatics, that are found in the elevator and fork-lift arts. Referring now also to FIGS. 4-6, frame 41 preferably includes a connector plate 61 at a second end 63 opposite first end 51 and proximate head package 7 when frame 41 is in first position 43, and through which each of cables 23 pass in spaced relation. The frame can also advantageously include a retraction system for retracting the ends of the cables toward the connector plate after they are disconnected from the IHP. The retraction system can, for example, spring bias the cables or use counterweights to retract the cables. FIG. 6 illustrates a plurality of elongated tension springs 65, each having a first end 67 proximate connector plate 61 connected to a different one of the plurality of cables 23, and each having a second end 68 distal from connector plate 61 connected to a fixed member 69 within frame 41. The springs 65 bias each of cables 23 such that a connector 71 at first end 29 of each of cables 23 is retracted towards connector plate 61 when each of cables 23 is disconnected from head package 7. Horizontal cross bars 73 extending between opposite sides 75 and 77 of frame 41, as illustrated in FIG. 5, provide support to at least some of the plurality of cables 23 between first end 51 of frame 41 and second end 63 of frame. Vertically arranged spacers 79 prevent crossing of at least some of cables 23 between first end 51 of frame 41 and second end 63 of frame 41. First end 51 of frame 41 is preferably open such that cables 23 freely hang down out of frame 41 in all frame positions and extend in catenaries to control panels 33 at their second ends 35 (FIGS. 1-3). Removable cover plates (not shown) can be used, if desired, to cover opening 31 and provide more usable deck space when frame 41 is in second position 45 in sub-space 17. A temporary platform 81 provides operator access to first ends 29 of cables 23 for connecting them to IHP 7 when frame 41 is in first position 43. A seismic hold-down 83 of a type known in the art, such as a clevis arrangement, at top 47 of wall 5 latches to frame 41 and provides stability in the event of a strong vibration. Whereas particular embodiments of the present invention have been described above for purposes of illustration, it will be appreciated by those skilled in the art that numerous variations of the details may be made without departing from the invention as described in the appended claims.