Patent Number: 046438670
Section: description

DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS Referring now to the drawings, and more particularly to FIG. 1 thereof, there is shown a first embodiment of the new and improved nuclear reactor refueling machine of the present invention as generally indicated by the reference character 10. The refueling machine 10 is seen to include, in part, a vertically disposed outer stationary mast 12 upon the lower end of which there is mounted a support sleeve 14. The sleeve 14 is annularly disposed about the mast 12 so as to completely encircle the same, and flanged edge portions 16 of the sleeve 14 are secured together in a butt-contact mode by means of suitable bolt fasteners 18. The stationary mast 12 has conventionally mounted thereon three roller bracket assemblies 20 which are equiangularly disposed about mast 12 in a circumferential array, although only two of the roller bracket assemblies 20 are shown in this figure. The roller bracket assemblies 20 project radially outwardly of mast 12, and also extend radially inwardly of mast 12 so as to mount thereon suitable roller mechanisms, not shown, internally of the stationary mast 12 for operatively engaging the refueling machine inner mast or gripper tube, also not shown, for facilitating the telescopic movement of the inner mast or gripper tube relative to the outer stationary mast during performance of refueling operations. Sleeve 14 is therefore provided with suitable apertures or windows 22 so as to accommodate the locations of the roller bracket assemblies 20 when the sleeve 14 is mounted upon the stationary mast 12. In accordance with the particularly unique features of the fuel assembly scanning system and/or fuel assembly-reactor core alignment system of the present invention, sleeve 14 has four, upwardly extending finger portions 23 upon which are respectively mounted four television cameras 24 by means of suitable brackets 26, although only three camera mounting systems are disclosed in this figure. The cameras 24 are oriented vertically with their axes disposed parallel to the axis of the stationary mast 12 and with the camera lenses oriented vertically downwardly. The cameras 24 are also disposed in a circumferential array about the stationary mast 12, and are substantially equiangularly spaced, although the accommodation of the existing roller bracket assemblies 20 of the otherwise conventional refueling machine may dictate a slight modification of the precise angular spacing or separation between adjacent television camera systems. Each camera 24 has operatively associated therewith a respective light source 28, and consequently, the scanning system of the present invention will include four light sources 28 substantially equiangularly disposed in a circumferential array about the longitudinal axis of stationary mast 12, although only one light source 28 is shown in FIG. 1. Each light source 28 is secured to the lower end of support sleeve 14 by means of suitable brackets 30 and serves to project its light beam in a substantially horizontal direction transverse or perpendicular to the longitudinal axis of stationary mast 12 in order to illuminate a sector portion of a reactor core fuel assembly 32 of at least 90.degree.. The fuel assembly 32 and its grid strap 34 are illustrated as being retracted into the stationary mast 12 by means of the inner mast or gripper tube, not shown, as would be the case during a refueling operation. In addition to the cameras 24 and the light assemblies 28, the scanning system of the present invention is completed by the further provision of four mirror assemblies 36 secured to the lower end of support sleeve 14 by suitable bracket assemblies 38. The mirror assemblies 36 are disposed about the axis of stationary mast 12 in a substantially equiangularly array, however, for clarity purposes, only one mirror assembly is illustrated in FIG. 1. Each of the mirror assemblies 36 is disposed directly beneath its respective television camera 24, and is inclined with respect to a horizontal plane at an angle of 45.degree.. In this manner, the sector portion of the reactor core fuel assembly 32 illuminated by means of the corresponding light source 28 is able to be visually scanned by means of the particular mirror assembly 36 and the scanned image transmitted to the respective television camera 24. Each camera assembly 24 is of course provided with suitable power and signal cable means 40 whereby the images seen by the camera assemblies 24 as transmitted by the mirror assemblies 36 can be further transmitted to television monitors, not shown in FIG. 1, which may be located at a remote location for viewing by the refueling machine operator or personnel, such as, for example, upon the refueling machine trolley, also not shown. It is to be appreciated that while the mirror assembly 36 shown in FIG. 1 is in fact the particular mirror assembly operatively associated with the particular camera assembly 24 shown in the extreme right portion of FIG. 1, the light source assembly 28 shown in FIG. 1 is not the corresponding light source assembly for the illustrated mirror assembly 36 and the right-most camera assembly 24, but is operatively associated with the camera assembly 24 which is illustrated in the extreme left portion of FIG. 1, its corresponding mirror assembly having been omitted for clarity purposes. Similarly, the light source assembly operatively associated with the illustrated mirror assembly 36 and the right-most camera assembly 24 has also been omitted from FIG. 1 for clarity purposes. It is lastly to be appreciated that while the camera and mirror assemblies 24 and 36, respectively, are co-axially aligned, each respective light source assembly 28 is angularly offset in the circumferential direction so as to properly illuminate the particularly desired sector of the reactor core fuel assembly 32 for scanning by the respective mirror assembly 36. In operation, it will be readily understood that during the performance of a refueling operation, the refueling machine will serve to remove a fuel assembly 32 from the reactor core, and it is desired to scan the entire external surface area of the fuel assembly 32 in order to detect or determine the existence of any damage or defects upon the fuel assembly 32 or its associated grid strap 34. The particular fuel assembly 32 may in fact be one which is to be entirely removed from the reactor core for refueling with fresh or new fuel, or simply one which is being transferred from one section of the reactor core to another section thereof. In either instance, the fuel assembly 32 will have been grasped by means of the refueling machine inner mast or gripper tube, not shown, and its associated gripper mechanisms, also not shown, and hoisted vertically out from the reactor core so as to be retracted within the outer stationary mast 12 of the refueling machine. As the fuel assembly 32 is moved vertically upwardly as denoted by arrow A, successive axial portions of the fuel assembly 32 will be continuously scanned by means of the light-mirror-camera system of the present invention whereby any defects or damage existing upon the external surface of the fuel assembly 32 or grid strap 34 will be able to be viewed by means of the refueling machine operator or personnel upon their television monitors. In view of the fact that the scanning system of the present invention includes four substantially equiangularly spaced, circumferentially arranged scanner assemblies, each capable of viewing a circumferential sector of the fuel assembly 32 of at least 90.degree., the entire circumferential surface area of the fuel assembly is able to be scanned. In lieu of utilizing the camera system of the present invention for its scanning operation, or in addition to the use of such apparatus in such an operational mode, the camera system of the present invention may also be utilized to facilitate the insertion of either a new or transferred fuel assembly 32 into an awaiting spacial location within the reactor core. In accordance with such an operational mode, the mirror assemblies 36 are simply removed and the light assemblies 28 directionally re-oriented so as to project their light beams downwardly for illumination of the reactor core. In this manner, the television cameras 24 can view the illuminated core, and in particular a core space into which the fuel assembly 32 may be inserted when moved in the vertically downward direction as denoted by the arrow B. Referring now to FIGS. 2-4, a second embodiment of the present invention is disclosed, and it is noted that corresponding parts of the system of FIGS. 2-4, relative to those of the system of FIG. 1, are denoted by the same reference characters except that all of the reference characters are in the 100 series. The refueling machine is generally designated by the reference character 100 and is seen to include the outer stationary mast 112 which is suspendingly supported from the refueling machine trolley 150 by means of a support mast 152. The trolley 150 is schematically illustrated as being movable along a suitable track system 154, and atop support mast 152 there is disposed the hoist drive system 156 for the inner mast or gripper tube, not shown, of the refueling machine. In lieu of the camera, light, and mirror assemblies 124, 128, and 136, respectively, being secured to or mounted upon a support sleeve as in the first embodiment of FIG. 1, the various assemblies are mounted upon a support module or framework which is suspendingly supported upon the lower end of the refueling machine outer mast 112 by means of two stainless steel support cables 158, only one of which is shown in FIG. 2. The cables 158 are routed vertically upwardly upon opposite sides of the outer mast 112 so as to pass over a first set of sheaves 160 mounted upon the upper end of mast 112 by suitable support bands 162, and a second set of sheaves 164 mounted upon one end of the bottom deck of trolley 150. The cables 158 then continue upwardly so as to be secured to two hand-operated winches 166 which are mounted atop trolley 150. The power and signal cables 140 for the television cameras 124 are similarly routed upwardly along mast 112 by being intertwined with the support cables 158, and ultimately, cables 140 are operatively connected to the television monitors and video tape recorder apparatus disclosed at 168 upon the refueling machine trolley 150. The basket-type support module or framework upon which the camera, light, and mirror assemblies 124, 128, and 136, respectively, are mounted is seen to include an upper annular ring member 170 circumferentially surrounding the outer mast 112, and a lower annular ring member 172 similarly circumferentially surrounding the outer mast 112, the ring members 170 and 172 being fixedly secured together by means of five substantially vertical, circumferentially spaced struts or columns 174. As best seen in FIG. 3, four of the five struts 174 serve to mount the television cameras 124 thereon by means of suitable brackets 126. It is to be readily appreciated that by means of the relatively easy movement of the basket-type framework along mast 112 as dictated by control of the winches 166 and the support cables 158, the positioning of the framework upon the lower end of mast 112 may be efficiently controlled from the remote location of the operator or personnel trolley 150. Still further, should maintenance, repair, or replacement of any one of the camera, light, or mirror assemblies 124, 128, or 136, respectively, prove to be necessary, the entire framework may be simply removed from the lower end of mast 112 and hoisted vertically upwardly out of the reactor core cavity water without the necessity of dewatering the cavity or lowering the water level thereof. In order to accomplish such an operation in a remote controlled manner, an aligning fixture or workholder 176 is disposed at a position laterally off to one side of the reactor core and at a sufficient depth below the lower end of stationary mast 112 so as to permit the basket-type framework 178 to be lowered relative to mast 112 until the same is freed therefrom. In particular, the trolley 150 would be initially moved along its track 154 until the mast 112 was co-axially aligned with fixture or workholder 176. The winch drives 166 would then be operated so as to lower the framework 178 onto the fixture or workholder 176. The support cables 158 would then be disengaged from the sheaves 160 disposed upon mast 112, and subsequently, the trolley 150 would then be moved back toward the right, as viewed in FIG. 2, toward its initial illustrated position. The winch drives 166 may then be operated so as to vertically lift the basket framework 178 out from the reactor core cavity water in order that the necessary repair, maintenance, or replacement work can be performed. Re-mounting of the framework 178 upon the mast 112 is of course to be performed in a similar but reverse operational mode. As was the case with the first embodiment of the present invention, the mirror assemblies 136 of the second embodiment may also be removed from the framework 178 and the light assemblies 128 directionally re-oriented so as to project their light beams vertically downwardly for illumination of the reactor core in order to facilitate the insertion of a fuel assembly within an awaiting spacial location within the reactor core. Obviously, many modifications and variations of the present invention are possible in light of the above teachings. It is therefore to be understood that within the scope of the appended claims, the present invention may be practiced otherwise than as specifically described herein.