Patent Number: 052805085
Section: description

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to FIG. 1, a fuel bundle B is shown, removed from a reactor. The fuel bundle has been placed in a holding pool 12, and had its lifting handle, channel and upper tie plate removed. As these items are conventional, they are not shown herein. Typically, the bundle is held vertically upright in a fuel handling machine (also conventional and not shown). For the convenience of the reader, the machine is likewise omitted, and the bundle is shown in the upright position. The worker manipulates handles H. Handles H effect the latching and unlatching of grasping mechanism G. Grasping mechanism G attached to the part length rod A. This grasping of the part length rod A must be made in a matrix of upstanding full length rods F. Referring to FIGS. 2 and 3, the dimensions of this problem can be understood. Specifically, full length rods F and an interior water rod W are of the order of 160" in length. The part length rod A is approximately 100" in length. Viewing the schematic of FIG. 2, it can be seen that spacer S1 and spacer S2 overlie the top of part length rod A. Part length rod A is at spacer S3, finally braced in the full upright position. It becomes apparent that access to a tip T at the end of part length rod A must occur through the cell matrix of spacers S1 and S2, overlying tip T. Referring to FIG. 3, an enlarged perspective of the upstanding fuel bundle is illustrated. A pole P with a grasping tool G at the bottom portion thereof is shown penetrating the matrix of the upstanding fuel bundle, including the lower tie plate L, the full length fuel rods F, a water rod W, to the top of the part length rods A. Part length rods A at spacer S3 as can be seen in order for pole P and grasping tool G to reach tip T of the part length rod A, passage through the cell matrix of spacers S1 and S2 has to occur. Referring to FIG. 4A, a part length rod A is shown. The part length rod includes a threaded lower tip 20, and attached sealed tube 22, an end tip T. Threaded tip 20 seals tube 22 at one end. Tip T seals the tube at the opposite end. A group of fuel pellets 30 compressed by spring 32 complete the construction of the part length fuel rod. Viewing the rod A as set forth in FIG. 4A, two important things are worthy of note: First, in the preferred embodiment of this invention, part length rod A is typically threadedly attached to lower tie plate L. Typically, lower tie plate L defines female threads. The lower threaded tip 20 defines corresponding male threads. To absolutely assure against vertical motion of the part length rod A, the rod is rotated with threaded engagement to lower tie plate L (see FIG. 3). Secondly, the part length rod includes a tip T. It is this tip T illustrated in more detail in FIG. 4B which constitutes the invention hereof. Referring to tip T, this tip includes a conventional sealing portion 40, the function of which is known in the prior art and here will be briefly described. Typically, portion 40 seals the end of the tube 22. It has an aperture 42 through which the fuel may be pressurized by gases chosen to suppress fusion gas production during the reactive lifetime of the fuel rod. As this is well known in the prior art, it will not be further discussed herein. Portion 44 of the tip T constitutes the novel portion of the tip. Consequently, it will now be described in more detail. First, tip T includes a cylindrical mass 46. This cylindrical mass has three distinctive features. First, it is provided at the upper end with a rounded gathering surface 47. As will hereinafter be more fully understood, gathering surface 47 enables a tool in a substantially blind condition to be gathered to the tip T for the removal and replacement of the rod. Secondly, the tip includes a longitudinal keyway 50. Keyway 50 is displaced from the longitudinal axis 49 of the cylindrical mass 46. It functions to provide a surface on tip T through which substantial torque can be applied. Thus, by manipulating the tip T at keyway 50, threads 20 (see FIG. 4A) can be screwed and unscrewed for insertion and removal of the part length rod A. Finally, a female cylindrical segment 54 has been removed from the cylindrical mass 46. Preferably, this removed section 54 is at the bottom end of keyway 50, at some distance removed from rounded tip 47. As will hereinafter made more apparent, female cylindrical segment 54 enables the tip T to be positively grasped to enable lifting parallel to axis 49 of the entire part length rod A. Having set forth the construction of the tip, three discrete tools will now be described: First, and with reference to FIGS. 6, 7A and 7B, a tool including a spring key and male cylindrical segment will be discussed. Thereafter, and with reference to FIGS. 8, 9A and 9B, a tool which grasps only the periphery of the tip T for both lifting and rotation will be set forth. The reader will understand that this tool will not be utilized where either large lifting forces or large turning or torque forces are required on the partial length rod A. Finally, and with respect to FIGS. 10A and 10B, a socket for applying a large turning force on the part length rod A will be set forth. Referring to FIG. 6, the pole P utilized with this invention is set forth. Pole P includes an upper cable attachment clevis 60, having a crossbore 62. This clevis 60 at crossbore 62 is conventionally attached to an overhead cable mechanism 14. Utilizing the pendulous weight of pole P and grasping tool G, verticality of the entire pole P arrangement is assured. It is necessary that pole P have relatively moving parts. These relatively moving parts are utilized for latching and unlatching of the grasping mechanism G. This being the case, and at the top of the pole, there is a knurled knob 64 and a threaded inner rod 66. Knurled knob 64 bears against a knurled handle 68. Handle 68 connects to an outer portion of the pole P. Looking at the end of the pole adjacent grasping mechanism G, it can be seen that there is required an outer portion of the pole 70, and an inner portion of the pole 72. Further, it will be understood that to operate the grasping mechanism G, relative reciprocation of the members 70, 72 must occur. Accordingly, knurled handle 68 is attached to outer portion 70. Threaded shaft 66 is attached to inner portion 62. By manipulation of handle 68, relative to shaft 66, corresponding movement of outer portion 70 relative to inner portion 72 occurs along the full length of the pole. Accordingly, the grasping mechanism G may be manipulated. Thirdly, and finally, the reader must realize that the pole P is of considerable length. Not only must the pole penetrate 60" into the radioactive environment of the upwardly exposed fuel bundle, but the pole must pass through a sufficient amount of water so that the maintenance personnel M manipulating the pole P are shielded from the ambient radiation. It thus will be understood that the sheer removal of the maintenance personnel M from the point of manipulation of the part length rod A constitutes one of the difficulties encountered in this invention. Because of this overall length, it is required to provide for breaking the pole P into two discrete sections. Accordingly, opposed flanges 80 on outer section 70 and a corresponding joining device on inner pole section 72 (not shown) are utilized so that pole P can be shipped in two separate and discrete sections. Having set forth the operation of the pole and emphasizing that the outer section 70 reciprocates with respect to the inner section 72, attention may now be devoted to a first embodiment of the grasping tool shown in FIGS. 7A and 7B. Affixed to shaft 72 there is included a cylinder 90. Cylinder 90 defines a concentric bore 92. Bore 92 is exposed outwardly to and towards tip T, and receives tip T concentrically thereof. Cylinder 92 is provided with an end which mates with taper 47 at the end of tip T. Cylinder 90 is slotted with a longitudinal keyway 94. It is the function of keyway 94 to receive a spring loaded tang 96. Spring loaded tang 96 and its attachments can be simply summarized. Tang 96 includes a second thickened end 97 which end 97 forms the weld point to cylinder 90. Tang 96 extends from weld point 97 to a key 98. It is the function of the key 98 to fit into keyway 50. As will hereinafter be described, registry of key 98 to keyway 50 provides a tactile signal to maintenance personnel M manipulating pole P so that rotational registration of gripping mechanism G can be determined at a distance of more than 20011 under conditions where observation of the engagement of the gripping mechanism G to the tip T simply cannot effected. Finally, and here shown at the distal end of tang 96, there is provided a male cylindrical segment 99. Male cylindrical segment 99 is complementary to female cylindrical segment 54. That is to say, once key 98 registers to keyway 50, and cylinder 90 at bore 92 is fully advanced onto tip T, male cylindrical segment 99 fits into female cylindrical segment 54, to completely fill in the cylindrical profile of the tip T. It can be seen with respect to FIG. 7A that such engagement is about to occur. By referring to FIG. 7B, locking of the grasping mechanism G can now be set forth. Referring to grasping mechanism G, it can be seen that outer pole segment 70 is connected to a sleeve section 102. Sleeve section 102 is open, so as to fit over tip T, when tip T has male cylindrical segment 99 occupying female cylindrical segment 54, key 98 occupying keyway 50, and tang 96 fully received within its slot 94. Having disclosed these constructions, the operation of sleeve 102 to lock to tip T of part length rod A can now be easily understood. With simultaneous reference to FIG. 1A, pole P is manipulated with respect to bundle B at a position overlying the part length rod P. Since the pole P and the grasping mechanism G do not have a dimension exceeding that dimension of an individual cell within spacers S1, S2, lowering of the grasping mechanism G at the end of pole P through spacers S1, S2 at the corresponding cell position easily occurs. When contact is made with tip T, pole P is rotated. At the same time, key 98 is deflected upwardly by gathering surface 47 on tip T. Rotation of pole P will occur until key 98 registers to keyway 50. At this point, the keyway 50 and key 98 will cause the relative rotation of pole P with respect to part length rod A to suddenly cease. This cessation of rotation will be felt by the maintenance worker M, some distance from fuel bundle B as he stands on catwalk 16. Once this rotational registration has occurred, grasping mechanism G will be advanced onto tip T. Such advancing will occur until a full position of penetration is reached. At this juncture, female segment 54 on tip T will be occupied by male segment 99. This will be accompanied by an additional tactile indication, which will include the end of the limit of travel of pole P and the grasping mechanism G down onto the top of part length rod A at tip T. Thereafter, sleeve 102 will be advanced. It will advance to a position overlying tang 96 at key 98 and male cylindrical segment 99. Firm locking of the grasping mechanism G and pole P to the part length rod A will occur. Typically, the grasping mechanism G will be maintained firmly fixed at tip T during its inspection. Such inspection can include the conventional removal of flocculants and other debris from the exterior of the part length rod A, with visual photographic and other non-destructive examinations occurring to the part length fuel rod A. Presuming that either the part length fuel rod A will be returned to the bundle B or alternately be replaced in bundle B, releasing of the part length rod A must be understood. It can be seen that male cylindrical segment 99 is provided with a complementary climbing surface 122. Presuming that sleeve 102 is withdrawn by corresponding withdrawal of outer section 70 of pole P, upward vertical movement of pole P will no longer result in lifting of partial length fuel rod A. Instead, male cylindrical segment 99 will climb free of female cylindrical segment 94, through the coaction of the climbing surface 122 with the edge of the female cylindrical segment. This will cause corresponding lifting of tang 96, enabling complete withdrawal of the grasping mechanism G. With respect to the apparatus set forth in FIGS. 6, 7A and 7B, the reader will understand that a universal type tool has been disclosed. The disclosed tool provides positive locks to tip T at the end of partial length rod A. These positive locks include both vertical lifting and application of torque to tip T. Referring to FIGS. 8, 9A and 9B, a second type of pole P, here denominated P', and gripping mechanism G, here denominated G', is set forth. Referring to FIG. 8, pole P includes clevis 62 overlying two counter-rotating handles 60, 162. Handle 162 is held stationary. Handle 60 is rotated. Upon such rotation, outer member 70 moves longitudinally of pole P with respect to inner member 72. As will hereinafter be explained with more detail, it effects engagement and disengagement of grasping mechanism G'. As before, an opposed flange 80 on outer section 70 and a mechanism (not shown) on inner mechanism 72 enables breaking of the pole P for convenient shipping and/or storage. Construction of the particular gripping mechanism G' is easy to understand. Inner member 72 has fastened thereto a cylinder 190. Cylinder 190 defines a female bore 192, for receiving the cylindrical portion 46 of tip T at the end of part length rod A. Typically, cylinder 190 is slit. It is slit at three respective cylinder slits 194, at approximate 120.degree. intervals, about an axis 196 of the cylinder. Additionally, the cylinder side wall is tapered. It tapers from a narrow dimension at the upper end 198 of the cylinder to a thickened dimension 199, at the lower end of the cylinder. Stopping here and ignoring all other constructions, the insertion and removal of cylinder 190 over tip T can be understood. As gripping tool G' comes down onto and over tip T, the respective segments of cylinder 190 will move away from cylinder 46. When it moves away from cylinder 46, capture of the tip T will occur. The reader can further see that the taper having a thin portion 198 at the upper end of bore 192 and a thickened portion at the lower end 199 of bore 192, will have an advantage in gripping the cylindrical side walls 46 of tip T. Specifically, the cylinder from top to bottom will fit flush with respect to the top to bottom cylindrical side walls of cylinder 46 of tip T. There remains to be understood how cylinder 190 may be firmly locked to the exterior of tip T. A second and reciprocating tip 202 is provided. Tip 202 has a thick portion 204 at the upper end, and a thinned portion 206 at the lower end. Sleeve 202, unlike cylinder 190, does not have slits. Accordingly, and once it is advanced over cylinder 190, firm capture of cylinder 190 will occur. Assuming that cylinder 190 is over the cylindrical portion 196 of tip T, and sleeve 202 is advanced over cylinder 190, firm engagement of the exterior of tip T will occur. At this point, the reader can note two differences from the mechanism set forth in FIGS. 9A and 9B, with respect to the mechanisms of FIGS. 7A and 7B. First, and presuming that pole P is utilized to apply torqued partial length rod A at tip T, no positive lock with respect to any keyway will occur. Accordingly, at higher degrees of torque, slippage may be expected. In the ordinary case, and presuming that threads 20 of partial length rod A are not stuck with respect to the lower tie plate, removal of the partial length rod A may occur. However, if sticking occurs, use of another tool may well be desired. Secondly, no locking of the grip mechanism G' occurs with respect to the female cylindrical cavity 54. Accordingly, if large lifting forces are required, again tool substitution may be utilized. It will be appreciated that the engagement of the tool mechanism G' shown on FIGS. 9A and 9B is relatively easy. This being the case, and assuming normal attachment of part length rod A in a fuel bundle B, use of this tool will be preferred. It may be desired to apply just torque to tip T. This being the case, the tool of FIGS. 10A and 10B may well be utilized. Referring to FIGS. 10A and 10B, a solid tool sleeve 300 is illustrated. Tool sleeve 300 has been slotted at a weld preparation area 302 for the receipt of a key 304. Key 304 is affixed as by welding to slot 302. Sleeve 300 is conventionally attached to a pole P; relatively reciprocating parts are not required. In operation, sleeve 300 fits over and receives tip T. Key 304 is registered to keyway 50 in tip T. Rotation under high torque of tip T and attached part length rod A can occur. Such a tool can be used as desired for partial length rod removal. It is to be noted that the grasping tool arrangements here shown are capable of being conveniently manipulated with respect to the end of a partial length rod A. It will further be understood that absolute verticality of the tip T of the end of the partial length rod A is never required. The respective gathering surfaces and conformance of the various grasping mechanisms G and G' enable the practical operating parameters of a reactor to be accommodated.