Patent Number: 051749475
Section: description

DETAILED DESCRIPTION OF THE INVENTION In the following description, like reference characters designate like or corresponding parts throughout the several views of the drawings. Also in the following description, it is to be understood that such terms as "forward", "rearward", "left", "right", "upwardly", "downwardly", and the like, are words of convenience and are not to be construed as limiting terms. Referring now to the drawings, and particularly to FIGS. 1 and 2, there is illustrated a nuclear fuel pellet turning apparatus of the present invention, being generally designated 10. The pellet turning apparatus 10 is used by an operator for handling a plurality of nuclear fuel pellets P at a time and facilitating surface inspection of the pellets P (FIGS. 18 and 23). The pellet turning apparatus 10 is disposed upon a work table 12 and under an exhaust hood 14 contained in an enclosed isolation chamber. A pair of spaced upright brackets 16, 18 are mounted on the work table 12 adjacent the pellet turning apparatus 10 for receiving and supporting a pellet supply tray 20 next to the pellet turning apparatus 10. In its basic components, the pellet turning apparatus 10 includes a pellet turner assembly 22 cable of supporting the pellets P and an interface assembly 24 coupled to the pellet turner assembly 22. The pellet turner assembly 22 can be operated to accomplish two functions. First, the pellet turner assembly 22 is operable for producing simultaneous turning of the pellets P in situ (i.e., rolling in place) to permit visual inspection of the entire circumferential surfaces of the pellets. Second, the pellet turner assembly 22 is also operable for producing simultaneous tilting of the pellets P to permit visual inspection of the opposite edges of the pellets. The interface assembly 24 is coupled to a pellet loading end 22A of the pellet turner assembly 22 and is operable for disposing a pellet transfer end 20A of the pellet supply tray 20 at a desired elevation above or below the loading end 22A of the pellet turner assembly 22 to facilitate transfer of uninspected pellets from the pellet supply tray 20 to the pellet turner assembly 22 and of inspected pellets from the pellet turner assembly 22 to the pellet supply tray 20. Referring to FIGS. 3-17, there is illustrated the pellet turner assembly 22 which includes a pellet turner deck 26 and a swivel mechanism 28. The pellet turner deck 26 supports pellets P in side-by-side spaced rows. The swivel mechanism 28 supports the pellet turner deck 26 and, in turn, is operable for swiveling and tilting the pellet turner deck 26 to allow simultaneous tilting of the pellets P and thereby permit an operator to easily visually inspect the opposite edges of the pellets for the presence of cracks and chips. More particularly, referring to FIGS. 3-13, the pellet turner deck 26 includes a base frame 30 mounted on the swivel mechanism 28, a plurality of elongated laterally-spaced rod-like members 32 extending between opposite ends of the base frame 30 and defining channels 34 between the members for receiving and arranging the pellets P in rows. The width of the channels 34 is greater than the diameter of the pellets P, as can be seen in FIG. 18, such that the pellets P are not supported upon the rod-like members 32. Also, means are provided on the base frame 30 for supporting the elongated rod-like members 32 at their opposite ends in spaced relation above the base frame 30. Such means takes the configuration of a support bar 36 attached on the right end and a base bar 38 attached on the left end of a network 40 of interconnecting frame members and a flat plate 42 which also make up the base frame 30. The flat plate 42 rigidly mounts the network 40 and, in turn, is attached on the upper end of the swivel mechanism 28. The swivel mechanism 28 is setup to normally support the deck 26 slightly off horizontal, for example, preferably at a five degrees incline perpendicular to the rod-like members 32. As best seen in FIGS. 8-13, the right ends 32A of the rod-like members 32 are bent ninety degrees and extend within vertical grooves 44 defined in laterally-spaced relation on the exterior of the support bar 36. The left ends 32B of the rod-like members 32 are received through holes 46 in the base bar 38 and biased by fasteners 48 and spring washers 50 to retain the right ends 32A in the grooves 44. As shown more specifically in FIGS. 3, 4 and 13-15, the pellet turner deck 26 also includes a pellet rolling plate 52 and an actuating mechanism 54 coupled to the plate 52. The pellet rolling plate 52 has a flat configuration and is movably supported on opposite ledges 56, 58 defined on the interior sides of the support and base bars 36, 38 of the base frame 30 below the pellet channel-defining rod-like members 32. In such position underlying the rod-like members 32, the rolling plate 52 supports the pellets P (FIG. 18) between the pellet channel-defining members 32. The slightly inclined mounting of the deck 26 ensures that all the pellets P are disposed against the rod-like members 32 on the same side of the channels 34. Such relationship enhances the visual inspection carried out by the operator. The actuating mechanism 54 is mounted on the base frame 30 and coupled to the pellet rolling plate 52 The actuating mechanism 54 is operable to produce oscillatory movement of the plate 52 in a direction generally perpendicular to the channel-defining members 32 for producing rolling or turning of the pellets P in situ on the plate and the channel-defining rod-like members 32. More, particularly, as best seen in FIGS. 16 and 17. The actuating mechanism 54 includes a handle 60 attached on a circular disc 62 rotatably mounted in an opening 64A of a bracket plate 64 which is fixed on and extends outwardly from the base frame 30. The actuating mechanism 54 also includes a cam element 66 secured in the circular disc 62 and extending upwardly through a slot 68 formed in a tab 70 which is fixed on and extends outwardly from the pellet rolling plate 52 above the bracket plate 64. As seen in FIG. 16, when the handle 60 is rotated clockwise from its solid line position to dashed line position, the pellet rolling plate 52 is moved linearly from the inwardly-displaced solid line position to outwardly-displaced dashed line position. Rotation of the handle 60 counterclockwise produced movement of the plate 52 in the opposite direction. The total movement of the pellets P is preferably at least approximately on full revolution of the pellet circumference. Referring to FIGS. 1 and 18, there is illustrated the swivel mechanism 28 having a universal ball joint 72 and a handle 74 movable between locking and unlocking positions. As mentioned above, the swivel mechanism 28 supports the pellet turner deck 26 and, in turn, once the handle 74 has been moved to the unlocking position of FIG. 18 is operable for swiveling and tilting the pellet turner deck 26 to simultaneously place the pellets in a tilted or inclined position. When the deck 26 and pellets P have been placed in the desired tilted position, the handle 74 is moved back to the locked position shown in FIG. 1. The above-described actuating mechanism 54 can be operated to oscillate the plate 52 to cause rolling or turning of the tilted pellets in situ. This permits an operator to easily visually inspect the entire perimeters of the end edges of the pellets for the presence of cracks and chips. After one end of the pellets are inspected, the swivel mechanism 28 is operated to rotate the pellet turner deck 26 through 180.degree. and reverse the tilting of the deck 26 to inspect the opposite end edges of the pellets. Referring now to FIGS. 19-25, there is illustrated the interface assembly 24 mounted on the right loading end 22A of the pellet turner deck 26 of the pellet turner assembly 22. The interface assembly 24 basically includes a tray elevating mechanism 76 and an actuating cam mechanism 78 operable to cause raising and lowering of the elevating mechanism 76. The tray elevating mechanism includes a plurality of engaging elements 80 mounted for reciprocal vertical movement on the exterior side of the support bar 36. Each engaging element 80 includes a plate 82 having a pair of vertical slots 84 which receive studs 86 extending from the support bar 36 to mount the plate 82 for vertical reciprocal movement. Each engaging element 80 further has an upstanding pin 88 insertable into a hole 90 (FIGS. 2 and 23) in the transfer end 20A of the pellet supply tray 20. The actuating cam mechanism 78 includes a handle 92 and a plurality of links 94 extending from the handle 92 and between and coupled with the engaging elements 80 of the tray elevating mechanism 76 via cam pins 96 on the links 94 extending through inclined slots 98 in the plates 82. The handle 92 is attached to a plate 100 which, in turn, is pivotally mounted to the base frame 30 by a stud 102. The pivotal movement of the plate 100 produced by pivotal movement of the handle 92 is transmitted and converted to linear movement of the interconnected links 94 via a cam pin 104 which is attached to the leftmost one of the links 94 and extends through an arcuate slot 106 formed through the plate 100. The offset of the radius of the arcuate slot 106 from the pivot point of the plate 100 produces linear movement of the links 94 upon rotation of the plate 100 and handle 92. In such manner, the actuating cam mechanism 78 is coupled to the tray elevating mechanism 76 and operable for moving the elevating mechanism to position the pellet transfer end of the supply tray either above or below the loading end 22A of the pellet turner assembly 22 depending upon the direction of rotation of the handle 92. Positioning of the pellet transfer end 20 A of the pellet supply tray 20 above or below the loading end 22A of the pellet turner assembly 22 correspondingly facilitates transferring of pellets to or from the pellet turner assembly 22. Referring to FIGS. 26-28, there is illustrated a pellet rake 108 which can be employed by an operator with the pellet turning apparatus 10 to slidably move pellets onto and from the deck 26. The rack 108 has a handle 110 at one end, a row of teeth 112 spaced apart by a distance adapting them to fit within the channels 34 of the deck 26, and interconnected by a flat connecting portion 114. The teeth 112 extend at a right angle to the flat portion 114. Referring to FIGS. 29 to 34, there are diagrammatic views of the operations involved in using the pellet turning apparatus 10 of the present invention for inspecting the entire cylindrical surfaces of the pellets (P) for dimensional quality, longitudinal cracks and chipped edges. FIG. 29 shows a pellet supply tray 20 disposed adjacent the pellet turner deck 26 of the turner assembly 22. The deck 26 is locked in stationary position and the transfer end 20A of the tray 20 is coupled to the interface assembly 24 (FIG. 19). The interface assembly 24 is operated to elevate the transfer end 20A of the tray 20 slightly above the loading end 22A of the deck 26. The two rectangles with diagonal lines represent multiple adjacent rows of pellets supported on the supply tray 20. Using the rake 108 (FIG. 26), an operator sweeps a first group of pellets from the supply tray onto the deck 26 to the position shown in FIG. 30 and then sweeps a second group of pellets onto the deck 26 to the position shown in FIG. 31. In order to provide clearance for swiveling and tilting the deck 26, as seen in FIG. 32 the emptied tray 20 is shifted to a position away from the deck 26. Next, as represented by FIG. 33, visual inspection commences with the operator moving the plate 52 (FIG. 15) to turn the pellets a full revolution for cylindrical surface inspection. The turning is accomplished by the operator manually swinging the handle 60 of the actuating mechanism 54 (FIG. 16) coupled to the plate 52 through 180.degree.. Then, edge chip visual is performed by the operator utilizing the swivel mechanism 28 to tilt the deck 26 and by again manually swinging the handle 60 to oscillate the plate 52 and turn the pellets. Makeup pellets are inserted by the operator to replace rejected pellets removed by the operator. Finally, the deck 26 is repositioned to its original orientation and the supply tray 20 is returned to the interfaced relationship with the deck as shown in FIG. 34. However, this time the interface assembly 24 is operated to lower the transfer end 20A of the supply tray 20 slightly below the load end 22A of the deck to facilitate transfer of the inspected pellets from the deck 26 to the supply tray 20. The rake 108 is again used by the operator to sweep the groups of inspected pellets from the deck 26 back onto the supply tray 20. It is thought that the present invention and many of its attendant advantages will be understood from the foregoing description and it will be apparent that various changes may be made in the form, construction and arrangement thereof without departing from the spirit and scope of the invention or sacrificing all of its material advantages, the form hereinbefore described being merely a preferred or exemplary embodiment thereof.