Patent Number: 050283790
Section: description

DETAILED DESCRIPTION OF THE INVENTION Referring to the drawing, FIG. 1 in particular, a typical power generating, water cooled and moderated nuclear reactor plant 10, comprises a reactor vessel 12, having a removable top (not shown) which closes and seals the pressure vessel during operating of the reactor. The removable top of the pressure vessel is disconnected and deposited elsewhere during shutdowns for refueling and/or maintenance service. Reactor vessel 12 is substantially filled with water 14 for moderating the fission produced neutrons, cooling the heat produced by the fissions reaction of the fuel and transferring the generated heat energy in the form of steam or pressurized hot water to means for conversion into mechanical work, such as a turbine. A fuel core 16 is located within the reactor vessel 12 submerged within the coolant/moderator water 14. The fuel core 16 is composed of a multiplicity of fuel bundles 18, each comprising a group of spaced apart sealed tube containers enclosing fissionable fuel and assembled and secured together in a composite unit. The upper end of the fuel bundle is provided with an end piece having a bail-like handle 20 for grasping by mechanical means to enable secure handling and transporting of the fuel bundles 18 when needed for refueling or rearranging partially spent fuel of the fuel core 16. To facilitate handling and transferring of fuel bundles 18 for refueling and/or fuel rearrangement of the core 16, reactor plants 10 commonly employ a fuel bundle handling platform 22. The fuel handling platform 22 usually comprises a platform which bridges across the top of the reactor vessel cavity and the reactor vessel 12 and is movable back and forth over the top of the reactor vessel cavity and the reactor vessel 12 on suitable means such as wheels and track. The movable platform 22 enables operating personnel working thereon to be positioned at any location above any fuel bundle 18 within the fuel core 16 for servicing. A fuel bundle handling mast 24 is supported on the fuel bundle handling platform 22 and is extendable downward therefrom into the reactor vessel 12 and the water 14 contained therein to just above the fuel core 16. The mast 24 can be arranged with the full length thereof sliding up and down to reach the core and retract therefrom, or telescoping in structure whereby it expands downward to reach the core and contracts upward therefrom. A grapple head 26 is mounted fixed on the lower end of the fuel handling mast 24 for reaching down into the reactor vessel 12 and its water 14 contents for grasping the fuel bundle handles 20 to lift and transport the fuel bundles 18. The grapple head 26 comprises a housing 28 including hooks 30 for attaching to handles 20 and securely grasping the fuel bundles 18 for transfer. Both the mast 24 and grapple hooks 30 of head 26 are operated remotely by personnel located above the reactor vessel 12, such as on the fuel bundle handling platform 22. In accordance with this invention, a television camera 32 is enclosed within the housing 28 of the grapple head 26. Camera 32 is provided with a transmitting and control cable 34 extending from the camera up the mast 24 to the movable platform 22 for personnel performing on the platform to observe underwater through the camera 32 and operate the camera and underwater lighting to enhance the view. The camera cable 34 is connected to a television monitor, such as monitor 36, for viewing by operating personnel, and/or a small screen viewing monitor can be affixed to the upper end of the handling mast 24 for the convenience of the personnel operating the grapple 26 through the mast. The camera 32 is preferable located within the upper portion of the grapple head housing above the grapple hooks 30 whereby it does not interfere with the mechanism of operation of the grapple hooks, which can be of conventional design. Camera 32 is preferably provided with a prismatic viewing head, and is horizontally rotatable within the grapple head housing 28 by the remote operator. The camera 32 is protected from radiation by a surrounding transparent quartz shield 38, such as an enclosing quartz cylinder, or other transparent material, and sealed therein by means of suitable seals such as o-rings to insure long term protection from radiation and water. The grapple head housing 28 is provided with several windows 40 for the camera 32 to view through in different directions and transmit views from all relevant points within the reactor vessel 12 and about the fuel core 16. Preferable at least three windows openings 40, 40' and 40" are provided in different sides or locations of the grapple head housing 28 to permit the camera 32 to view in several different directions whereby all relevant aspects within the pressure vessel about the fuel core can be observed. For instance, window opening 40 looks out horizontally from one side of the grapple head housing 28, a second window opening 40'looks out from a second side of the housing 28, and a third window opening 40" cooperates with window 40' in guiding a view in a different direction. Additional window openings in the housing 28 can of course be provided for the camera 32. Window openings 40 in the housing are in apt alignment with the prismatic viewing head of the camera 32. One window opening in the grapple head housing 28, such as window 40' in the second side, is arranged to view vertically downward from the central axis of the grapple head housing 28. One measure providing for achieving this vertically downward view for the camera 32, as shown in FIGS. 2, 3, and 4, comprises providing a cooperating window opening 40" below and aligned with window 40'in grapple head housing 28. Upper and lower, aligned window openings 40' and 40" are each provided with cooperating view reflecting angled surfaces 42 and 42', of approximately 45 degrees whereby the line of view of outward from the camera 32 within the grapple head housing 38 is turned about 90 degrees downward from horizontal to vertical, then turned again about 90 degrees laterally from vertical to horizontal back into the housing 38. Positioned generally centrally within the lower portion of the grapple head housing 28 is another view reflecting angled surface 42" of about 45 degrees which one more turns the view from surfaces 42 and 42' about 90 degrees downward from horizontal as received from surface 42' to vertical out through the open bottom of grapple head housing 28 and down between grapple hooks 30. With such an arrangement of window openings 40 in the grapple head housing 28 aligned with the prismatic viewing head of the camera 32, by rotating the camera 32 enclosed within the housing 28, the camera can record and transmit to a monitor 36 a vertical view downward on to the fuel core 16 to guide and manipulate the grapple hooks 30 for attaching to the handles 20 of submerged fuel bundles 18 for transfer within and about the reactor vessel 12 and for viewing and recording fuel assembly identifications. Additionally by remote rotation of the camera 32 and aligning the prismatic viewing head of the camera with other window openings 40 in the grapple head housing 28, the camera can record and transmit to a monitor 32 horizontal views within the reactor vessel 12 and about the fuel core 16 to inspect and determine if any submerged fuel bundles 18 are not properly positioned or seated within the fuel core 16. This arrangement provides protection for the transmitting camera 32 against physical damage while operating within the reactor vessel 12 under water, such as by collision with reactor components or fuel bundles 18. The versatile viewing capabilities of the camera 32 enclosed within the grapple head housing 28 also enable vertical viewing for examining the fuel core and verifying the core pattern and fuel bundle positioning therein.