Integrated head package cable carrier for a nuclear power plant

A cabling arrangement is provided for a nuclear reactor located within a containment. Structure inside the containment is characterized by a wall having a near side surrounding the reactor vessel defining a cavity, an operating deck outside the cavity, a sub-space below the deck and on a far side of the wall spaced from the near side, and an operating area above the deck. The arrangement includes a movable frame supporting a plurality of cables extending through the frame, each connectable at a first end to a head package on the reactor vessel and each having a second end located in the sub-space. The frame is movable, with the cables, between a first position during normal operation of the reactor when the cables are connected to the head package, located outside the sub-space proximate the head package, and a second position during refueling when the cables are disconnected from the head package, located in the sub-space. In a preferred embodiment, the frame straddles the top of the wall in a substantially horizontal orientation in the first position, pivots about an end distal from the head package to a substantially vertically oriented intermediate position, and is guided, while remaining about vertically oriented, along a track in the sub-space to the second position.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
This invention relates to cable carriers for cables connecting to an 
integrated head package of a nuclear reactor, and, in particular, to cable 
carriers which permit all of the power and control cables to be removed 
from the integrated head package at one time and that stores them in a 
protected environment leaving an operating floor in the containment 
completely unobstructed for maintenance and refueling operations. 
2. Description of the Prior Art 
Prior to refueling a nuclear powered reactor, it is necessary to remove and 
store the integrated head package (IHP). The IHP consists of a reactor 
vessel head, the control rod drive mechanisms (CRDM's), the control rod 
position indicators (RPI's), the cooling fans and other associated 
hardware. An IHP for a nuclear reactor is described in commonly owned U.S. 
Pat. No. 4,830,814, to Altman, included herein by reference. In 
preparation for removal of the IHP, all of the power and control cables 
that run to the CRDM's or RPI's from control cabinets located in the 
containment building, along with other electrical instrumentation cables 
must be disconnected between connector plates that are mounted on the IHP. 
Once they are disconnected from the IHP, these cables must be safely stored 
during refueling. In present plants, the cables are stored individually in 
various locations or are removed and stored in special articulating cable 
trays. The cable trays and cables take up valuable room on the operating 
deck and are subject to damage from operating personnel during refueling 
operations. 
Therefore, there is a need for a cabling arrangement for nuclear reactors 
wherein the cables can be removed from the operating floor during the 
refueling operation. There is also a need for a cabling arrangement for an 
IHP that protects the cables from accidental damage during normal 
operation of the reactor and during refueling. 
SUMMARY OF THE INVENTION 
These and other needs are met according to the invention in a cabling 
arrangement that includes a frame or cable carrier supporting power and 
instrumentation control cables connected to a head package on a nuclear 
reactor vessel. The frame can be withdrawn from the reactor vessel area to 
a remote area to clear an operating area near the reactor vessel. 
The cable carrier can include a connector plate, through which each of the 
cables pass, located near the head package for keeping the cables spaced 
apart from each other. The cable carrier can also include, for each cable, 
a mechanism for retracting a short length of cable extending beyond the 
connector plate, including the cable connector, towards the connector 
plate. 
It is an object of the invention to provide a cable carrier for a nuclear 
reactor vessel that, after disconnection of the cables from the reactor 
head, can be moved, with the cables, to an area remote from the reactor 
vessel such that an area on an operating deck around the reactor vessel is 
cleared. 
It is another object of the invention to provide a cable carrier for a 
nuclear reactor that affords maximum protection for the cables during 
refueling and maintenance operations. 
It is another object of the invention to provide a cabling arrangement for 
a nuclear reactor wherein the cables can be speedily disconnected and 
reconnected to the IHP. 
These and other objects of the invention will be more fully understood from 
the following description of the invention with reference to the 
accompanying drawings.

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.