Patent Number: 051046121
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 pressure 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 pressure 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 by and movable about 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 complementary 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 or the like remote viewing means 32 is enclosed within the housing 28 of the grapple head 26. Camera or other viewing means 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 or viewing means 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 or viewing mean 32 is located within the upper portion of the grapple head housing above the grapple hooks 30 whereby it does not interfere with the mechanism or operation of the grapple hooks, which can be of conventional design. Referring to FIGS. 2, 3 and 4 of the drawings, a generally horizontal support shaft 38, comprising a hollow cylinder is secured within the grapple housing 28 for supporting the hook 30 mechanism. Hollow cylindrical sleeves 40 are rotatably mounted on and around support shaft 38, with a sleeve attached to one of at least two complementary hooks 30. Rotatably mounted sleeves 40 are fixed in longitudinal axial positions on the support shaft 38, preferably each hook carrying sleeve being located adjacent to an end of the support shaft, and spaced a distance apart. A spacing sleeve 42 ca be positioned between sleeves 40 on shaft 38 to provide for apt spacing of the sleeve units. Thus arranged, with the rotation of sleeves 40 mounted on shaft 38 over a short arc, the pair of grapple hooks 30 pivot inward toward each other for the purpose of securely grasping a bail handle 20 of a fuel bundle and safely transporting same, then pivot backward away from each other to release a bail handle 20 of a fuel bundle to deposit the bundle at a suitable location. One version of this invention comprises a centrally positioned sleeve 40 with an integrated hook 30 directed in one direction and a pair of end positioned sleeves 40, one on each side of the central sleeve, with each of said end sleeve having a hook 30 directed in the opposite direction of the center hook 30. Thus the outer pair of hooks 30 face the center hook 30 which faces the pair of hooks whereby they complement each other to securely close upon each other and grasp a bail handle. Further in accordance with this invention, the hollow cylindrical support shaft 38 is provided with a pair of complementary orifices 44, positioned generally in a central area in the support shaft 38 between the sleeves 40, one orifice being located in the upper portion of the cylindrical shaft 38 and the other orifice opposite thereto in the lower portion of the cylindrical shaft. The paired upper and lower orifices 44 are vertically aligned one over the other to provide a direct in-line optical viewing path or line of sight downward through the center of generally horizontal support shaft 38 from above. Thus, a remote operator positioned above the grapple means can observe from overhead the area immediately below the grapple hooks 30 by a variety of means including a television camera 32 located above the grapple hooks 30. When a spacing sleeve 42 is employed mounted on the support shaft 38 between the sleeves 40, a pair of orifices 46 are provided in spacing sleeve 42 which aligned with and are generally conterminous to the perimeters of orifices 44 on the upper and lower opposite sides of the support shaft 38. Thus the two pairs of orifices 44 and 46 are each in-line vertically providing a direct optical viewing path or line of sight from above the grapple means to the area immediate below. To illuminate the area immediately beneath the grapple means for facilitating its operation under water by an overhead remote operation above the water's surface, lighting means are preferably associated with the fuel handling system or mechanism. In accordance with invention at least one light source is located within the generally horizontal support shaft 38 contained within grapple housing 28. A light source 48 is positioned inside either or both end areas of support shaft 38 which are surrounded by rotatably mounted sleeves 40 carrying grapple hooks 30. To enable the light source 48 to illuminate the area beneath the grapple hooks 30 for effective viewing by an overhead operator, orifices 50 and 54 are respectively provided in the lower portion of the support shaft 38 and also in a lower portion of the immediate surrounding sleeve 40 rotatably mounted on the shaft and carrying a grapple hook 30. The orifices 50 and 54 respectively in the lower portion of the shaft 38 and sleeve 40 are in alignment and generally conterminous in perimeters when sleeves 40 are rotated in a limited arc with the grapple hooks 30 pivoted back away from each other in a retracted position for release of an object form the grasp of the hooks. When the sleeve 40 is so positioned, light from the source 48 beams downward illuminating the area below the grapple head 26. One or more partitions 54 is provided within support shaft 38 between the light source 48 and the central portion of the shaft 38 containing the viewing orifices 44, and 46. This arrangement blocks light from the light source 48 from entering into the line of vision passing between the orifices 44 and 46 and thereby obscuring the field of view beneath the grapple head 26 and hooks 30 while fully illuminating the area beneath the grapple head 26 and 30 for enhanced operator vision. The measures of this invention provide for direct viewing and/or illuminating of an underwater object such as a fuel bundle through the grapple head and hooks depending therefrom without any need for fiber optics, light pipes or mirrors, and the like.