Patent Number: 047560673
Section: claims

1. The method of replacing an old split-pin assembly mounted in a guide tube of a nuclear reactor by a new split-pin assembly, said tube having a flange, said old split-pin assembly including an oil split pin having a flange secured to a flange of said guide tube by an old nut with the flange of said old split pin engaging the base of a counterbore in the bottom of said flange of said guide tube and the new split-pin assembly including a new split pin also having a flange to be secured to the flange of said guide tube by a new nut; the said method comprising severing said old split pin in the region below said flange of said old split pin into a first pin fragment which is separated from said flange of said old split pin in said guide tube, and a second fragment including said flage of said old split pin and said old nut, which second fragment remains secured to said guide tube with the region of said second fragment where the first fragment was separated exposed, engaging a drill with said second fragment in said exposed region where said first fragment was severed from said old split-pin fragment, said drill being positioned axially of said second fragment and having a bit having a diameter approximately equal to the diameter of the shank of said old split pin, operating said drill to drill axially along said second fragment to separate said second fragment into a third fragment including said flange of said old split pin and a fourth fragment including the remainder of said old split pin and said old nut, said third fragment being removable from said base of said counterbore in the bottom of said guide tube and said fourth fragment being removable from the upper part of said flange of said guide tube, removing said first pin fragment and said third and fourth fragments from said guide tube, and thereafter securing said new split-pin assembly in said guide tube by said new nut with the flange of said new split pin engaging said base of said counterbore in the bottom of said flange of said guide tube. 2. In the method of replacing an old split-pin assembly of a guide tube of a nuclear reactor by a new split-pin assembly, said guide tube having a flange, said old split-pin assembly including an old split pin having a flange secured to said flange of said guide tube by an old nut with the flange of said old split pin engaging the base of a counterbore in the bottom of said flange of said guide tube, said new split pin also having a flange; the method of removing said old split-pin assembly from said guide tube, the said method comprising severing said old split pin in the region below said flange of said old split pin into an a first pin fragment and a second fragment including the remainder of said old split pin, said flange of said old split pin and said old nut, said second fragment remaining secured in said flange of said guide tube by said old nut and said first fragment being separated from said second fragment exposing the region of said remainder of said old split pin where said first fragment was separated, engaging a drill with said second fragment in said exposed region where said first fragment was separated from the remainder of said old split pin, said drill being positioned axially of said second fragment and having a bit having a diameter approximately equal to the diameter of the shank of said old split pin, operating said drill to drill axially along said second fragment to separate said second fragment into a third fragment including said flange of said old split pin removable from said counterbore in the bottom of said flange of said guide tube and a fourth fragment including the remainder of said old split pin and said old nut, removable from the upper part of the flange of said guide tube, and removing said first pin fragment and said third and fourth fragments from said reactor. 3. The method of claim 1 including installing the new split pin in the space vacated by the old split-pin assembly by positioning the new split pin with the flange of said new split pin adjacent the bottom of the base of the counterbore in the flange of the guide tube, thereafter threading the new nut on said new split pin, torqueing the new nut so that said flange of said new split pin is in pressure-engagement with said bottom of said base of said counterbore, and crimping a cup extending from the top of said new nut to said new split pin. 4. Apparatus for replacing an old split-pin assembly secured to a guide tube of a nuclear reactor by a new split-pin assembly, said guide tube having a flange, said old split-pin assembly having an old split pin having a flange secured by a nut to the base of a counterbore in the bottom of said flange of said guide tube and said new split-pin assembly having a new split pin having a flange to be secured by a nut to said base of said counterbore in the bottom of the flange of said guide tube; the said apparatus including a first stand for mounting a guide tube having an old split-pin assembly mounted thereon, purely mechanical severing means, connected to said first stand and positioned thereon to sever said old split pin below the flange of said pin into a first split-pin fragment and a second fragment including the flange of said old pin and the remainder of said old pin and said old nut threaded on said remainder, said second fragment remaining secured to said flange of said guide tube by said old nut and said first fragment being separated from the remainder of said old split pin exposing the region of said remainder of said old split pin when said first fragment is severed, a drill mounted on said first stand in a position such that on rotation of said guide tube through a predetermined angle from the position where said first fragment was severed said drill is positioned generally coaxially with said second fragment, said drill having a bit having a diameter approximately equal to the diameter of the shank of said old split pin, said drill being oriented so that said bit is engageable with said exposed region, and means, connected to said drill, for driving said bit into said exposed region in drilling engagement generally coaxially with said second fragment to sever said second fragment into a third fragment including said flange of said old split pin removable from said counterbore in the bottom of said flange of said guide tube and a fourth fragment including said old nut and the remainder of said old split pin threaded to said old nut, said fourth fragment being removable from the upper part of the flange of said guide tube, and said apparatus also including a second stand spaced from said first stand, and means, on said second stand, for positioning a new split pin and a guide tube in cooperative relationship to be processed for securing the flange at said new split pin by a new nut into engagement with said base of said counterbore in the bottom of said flange of said guide tube. 5. The method of claim 1 wherein the replacing the old split-pin assembly by a new split-pin assembly is practiced with apparatus including a stand on which the guide tube is disposed for the processing for the old split-pin assembly, and the old split-pin assembly is severed into the old split-pin fragment and a second fragment in a first position of said stand and the second fragment drilled in a second position of said stand spaced circumferentially by a predetermined angle from the first position and the method includes the step of rotating the guide tube, after the severing of said old split pin into an old pin fragment and a second fragment, from said first position to said second position, and drilling the second fragment in said second position. 6. The method of claim 5 for replacing the old split-pin assemblies by new split-pin assemblies of a guide tube which includes a pair of split-pin assemblies spaced circumferentially by 180.degree. and the first position of the stand and the second position of the stand are spaced circumferentially by about 180.degree., and the said method includes the steps of severing one old split pin of one old split-pin assembly in said first position into a split-pin fragment and a second fragment, rotating said guide tube through 180.degree. from said first position to said second position, drilling said second fragment of said one old split-pin assembly in said second position, without rotating said guide tube, severing the other old split-pin assembly into a split-pin fragment and a second fragment in said first position of said stand, rotating said guide tube through about 180.degree., and drilling said second fragment of said other split-pin assembly in said second position of said stand. 7. The method of claim 2 wherein the method of removing the old split-pin assembly from the guide tube is practiced with apparatus including a stand on which the guide tube is disposed for the removing of the old split-pin assembly and the old split-pin assembly is severed into the split-pin fragment and the second fragment in a first position of said stand and the second fragment is drilled in a second position of said stand spaced circumferentially by a predetermined angle from said first position and the said method includes the step of rotating the guide tube after the severing of said old split-pin assembly into a split-pin fragment and a second fragment from said first position to said second position, and drilling the second fragment in said second position. 8. The method of claim 7 practiced to remove the old split-pin assemblies of a guide tube which includes a pair of split-pin assemblies spaced circumferentially by 180.degree. and the first position and second position are spaced circumferentially by about 180.degree., and the said method includes the steps of severing one split-pin assembly in said first position into a split-pin fragment and a second fragment, rotating said guide tube through about 180.degree. from said first position to said second position of said stand, drilling said second fragment of said one old split-pin assembly in said second position of said stand, without rotating said guide tube, severing the other old split-pin assembly into a split-pin fragment and a second fragment, then rotating said guide tube through 180.degree., drilling said second fragment of said other split-pin assembly in said second position of said stand and removing said split-pin fragments and said second fragments from the reactor. 9. Apparatus according to claim 4 for replacing a pair of old split-pin assemblies of a guide tube by new split-pin assemblies, said old split-pin assemblies being spaced circumferentially by 180.degree. about said guide tube, the said apparatus being characterized by that the drill is circumferentially spaced from the mechanical severing means by an angle such that when the guide tube is rotated through about 180.degree. after the severing of one of said old split-pin assemblies into a split-pin fragment and a second fragment by the severing means, the second fragment of said one old split-pin assembly is positioned coaxially with the drill and the other old split-pin assembly is positioned to be severed by said severing means. 10. For use in the replacement of an old split-pin assembly secured to a guide tube of a nuclear reactor with a new split-pin assembly, said guide tube having a flange, said old split-pin assembly including an old split-pin having a flange secured to a flange of said guide tube by an old nut with the flange of said old split pin engaging the base of a counterbore in the bottom of the flange of said guide tube; apparatus including a stand for removing said old split-pin assembly, the said stand including purely mechanical severing means mounted on said stand, means for positioning a guide tube, having an old split-pin assembly secured thereto, on said stand with said severing means in position to sever said old split-pin assembly into a split-pin fragment and a second fragment, said second fragment including said flange of said old split pin joined to the remainder of said old split-pin assembly and said old nut, the severing of said old split-pin assembly exposing the region of said old split pin from which said split-pin fragment was severed, and a drill mounted on said stand spaced circumferentially by a predetermined angle so that when said guide tube is rotated through said angle said drill is positioned to engage said exposed region and to sever said second fragment into a third fragment including said flange and a fourth fragment including said nut joined to the remainder of said split pin. 11. Apparatus for replacing an old split-pin assembly secured to a guide tube of a nuclear reactor by a new split-pin assembly, said guide tube having a flange, said old split-pin assembly having an old split pin also having a flange secured by a nut to the base of a counterbore in the bottom of a flange of said guide tube and said new split-pin assembly having a new split pin having a flange to be secured by a nut to said base of said counterbore in the bottom of the flange of said guide tube; the said apparatus including a first stand for mounting a guide tube having an old split-pin assembly mounted thereon, purely mechanical severing means, connected to said first stand and positioned thereon to sever said old split pin below the flange of said pin into a split-pin fragment and a second fragment including the flange of said old split pin and the remainder of said old split pin and said old nut, the severing of said split-pin assembly exposing the region of said old split pin from which said split-pin fragment is severed, a drill mounted on said first stand in a position such that on rotation of said guide tube through a predetermined angle from said mechanical severing means, said drill is positioned to engage said exposed region and drill said second fragment, and means, connected to said drill, for driving said drill to sever said second fragment into a third fragment including said flange of said old split pin and a fourth fragment including said old nut and the remainder of said old split pin; and said apparatus also including a second stand spaced from said first stand, and means, on said second stand, for positioning a new split pin and said guide tube from which said old split-pin assembly has been removed in cooperative relationship to be processed for securing the flange of said new split pin by a new nut into engagement with the base of the lower counterbore of said flange of said guide tube. 12. The stand of claim 11 wherein said drill has a bit having a diameter approximately equal to the diameter of the shank of the split pin and is mounted on the stand so as to be positioned coaxially with said shank of said second fragment on the rotating of the guide tube from the mechanically severing means by the predetermined angle. 13. The method of claim 1 wherein the old split pin of the old split-pin assembly extends below the undersurface of the flange of the guide tube and the old split pin is severed in the region below said undersurface of said flange of said guide tube without damage to said guide tube. 14. The method of claim 2 wherein the old split pin of the old split-pin assembly extends below the undersurface of the flange of the guide tube and the old split pin is severed in the region below said undersurface of said flange of said guide tube without damage to said guide tube. 15. The method of claim 1 wherein the old split pin of the old split-pin assembly is severed into a split pin fragment and a second fragment in the region between the crotch of the tines of the bifurcated end and the flange. 16. The method of replacing an old split-pin assembly mounted in a guide tube of a nuclear reactor by a new split-pin assembly, said guide tube having a flange, said old split-pin assembly including an old split pin having a flange secured to the flange of said guide tube by an old nut with the flange of said old split pin engaging the base of a counterbore in the bottom of said flange of said guide tube and the new split-pin assembly including a new split pin also having a flange to be secured to the flange of said guide tube by a new nut, with the flange of said new split pin engaging the base of a counterbore in the bottom of said flange of said guide tube; the said method comprising severing said old split pin of said old split-pin assembly in the region below said flange of said old split pin into an old split-pin fragment and a second fragment including the remainder of said old split pin and said flange of said old split pin and said old nut, said old split-pin fragment being separated from said flange of said guide tube and said second fragment remaining connected to said flange of said guide tube with the region of the remainder of said old split pin where the old split-pin fragment was severed exposed, by engagement with said exposed region, severing said second fragment into a third fragment including said flange of said old split pin and a fourth fragment including the remainder of said old split pin and said old nut, removing said split-pin fragment and said third and fourth fragments from said reactor, said third fragment being removed through the counterbore in the bottom of said flange of said guide tube and said fourth fragment being removed from the top of said guide tube, and thereafter securing said new split-pin assembly in said guide tube by said new nut with the flange of said new split pin engaging the base of the counterbore in the bottom of said guide tube. 17. In the method of replacing an old split-pin assembly of a guide tube of a nuclear reactor by a new split-pin assembly, said guide tube having a flange, said old split-pin assembly including an old split pin having a flange secured to said flange of said guide tube by an old nut with the flange of said old split pin engaging the base of a counterbore in the bottom of said nut; the method of removing said old split-pin assembly from said flange; said method comprising severing said old split pin in the region below said flange of said old split pin into an old split-pin fragment and a second fragment including the remainder of said old split pin and said flange of said old split pin and said old nut, said old split-pin fragment being separated from said flange of said guide tube and said second fragment remaining connected to said flange of said guide tube; with the region of the remainder of said old split-pin where the old split-pin fragment was severed exposed, by engagement with said exposed region, severing said second fragment into a third fragment including said flange of said old split pin and a fourth fragment including the remainder of said old split pin and said old nut, removing said split-pin fragment and said third and fourth fragments from said reactor, said third fragment being removed through said counterbore in the bottom of said guide tube. 18. The method of claim 16 wherein the replacement of the old split-pin assembly by a new split-pin assembly is carried out with apparatus including a stand on which the guide tube is disposed for the processing of the old split-pin assembly and the old split pin is severed in a first position of said stand and the second fragment is separated into third and fourth fragments in a second position of said stand spaced circumferentially by a predetermined angle from said first position and the said method includes the step of rotating the guide tube, after the severing of said old split pin into an old split-pin fragment and a second fragment, from said first position to said second position and separating said second fragment into third and fourth fragments with the second fragment in said second position by drilling of said second fragment in said second position. 19. The method according to claim 18 of replacing both split-pin assemblies of a guide tube wherein the guide tube includes a pair of split pins spaced circumferentially by 180.degree. and the first position and second position of said stand are spaced circumferentially 180.degree., and the said method includes the steps of severing one old split-pin assembly in said first position of said stand into a split-pin fragment and a second fragment, then rotating said guide tube through 180.degree. from said first position to said second position of said stand, severing said second fragment of said one old split-pin assembly into the third and fourth fragments in said second position of said stand, severing the other old split-pin assembly into a split-pin fragment and a second fragment in said first position of said stand, then rotating said guide tube through 180.degree. so that the split-pin fragment of said other split-pin assembly is in said second position of said stand, and severing said second fragment of said other old split-pin assembly into third and fourth fragments in said second position of said stand. 20. The method of claim 1 wherein the old split pin of the old split-pin assembly is severed above the region where the tines of said old split-pin are separated. 21. The method of claim 2 wherein the old split pin of the old split-pin assembly is severed above the region where the tines of said old split-pin are separated. 22. The stand of claim 11 wherein the drill has a bit having a diameter slightly greater than the diameter of the shank of the split pin and is mounted on the stand so as to be positioned coaxially with the second fragment on the rotation of the guide tube from the mechanically severing means by a predetermined angle. 23. The method of replacing an old split-pin assembly mounted in a guide tube of a nuclear reactor by a new split-pin assembly, said guide tube having a flange, said old split-pin assembly including an old split pin having a shank terminating in tines at the lower end and having a flange between said tines and the upper end of said old split-pin, said old split-pin assembly being mounted in said guide tube secured to the flange of said guide tube by an old nut with the flange of said old split pin engaging the base of a counterbore in the bottom of said flange of said guide tube and the new split-pin assembly including a new split pin also having a flange to be secured to the flange of said guide tube by a new nut with the flange of said new split pin engaging the base of the counterbore in the bottom of said flange of said guide tube; the said method comprising severing said old split pin of said old split-pin assembly in the region between the crotch of said tines and said flange of said old split pin into a first pin fragment and a second fragment including the remainder of said old split pin, and said flange of said old split pin and said old nut, said first fragment being separated from said flange of said guide tube and said second fragment remaining connected to said flange of said guide tube with the region of the remainder of said old split pin where the old split-pin fragment was severed exposed, by engagement with said exposed region, severing said second fragment into a third fragment including said flange of said old split pin and a fourth fragment including the remainder of said old split pin and said old nut, removing said first pin fragment and said third and fourth fragments from said reactor and thereafter securing said new split-pin assembly in said guide tube by said new nut with the flange of said new split pin engaging the base of the counterbore in the bottom of said guide tube. 24. In the method of replacing an old split-pin assembly of a guide tube of a nuclear reactor by a new split-pin assembly, said guide tube having a flange, said old split-pin assembly including an old split pin having a shank terminating in tines and having a flange between said tines and the upper end of said old split pin, said old split-pin assembly being mounted in said guide tube secured to said flange of said guide tube by an old nut with the flange of said old split pin engaging the base of a counterbore in the bottom of the flange of said guide tube; the method of removing said old split-pin assembly from said flange; the said method comprising severing said old split pin in the region between the crotch of said tines and said flange of said old split pin into an old split-pin fragment and a second fragment including the remainder of said old split pin and said flange of said old split pin and said old nut, said old split-pin fragment being separated from said flange of said guide tube and said second fragment remaining connected to said flange of said guide tube with the region of the remainder of said old split pin where the old split-pin fragment was severed exposed, by engagement with said exposed region, severing said second fragment into a third fragment including said flange of said old split pin and a fourth fragment including the remainder of said old split pin and said old nut, removing said split-pin fragment and said third and fourth fragments from said reactor, said third fragment being removed through said counterbore in the bottom of said flange of said guide tube. 25. In the method of replacing an old split-pin assembly of a guide tube of a nuclear reactor by a new split-pin assembly, said old split-pin assembly having an old split pin and an old nut, said old split pin having a flange intermediate its ends, said guide tube having a flange having an upper counterbore and a lower counterbore coaxial with said upper counterbore and in communication therewith through a coaxial hole through the bases of said counterbores, said old split-pin assembly being mounted in said counterbores with said old split pin extending coaxially through said counterbores and being secured in said counterbores by said old nut with said nut engaging the base of said upper counterbore and the flange of said old split pin engaging the base of said lower counterbore, whereby removal of said old split-pin assembly by exertion of an axial upward force on said old split pin is prevented by the engagement of said flange of said old split pin with the base of said lower counterbore; the method of removing said old split-pin assembly from said guide tube which comprises first removing a portion of the shank of said old split pin between said flange and that end of said old split pin on the side of said lower counterbore thus exposing the cross section of the remainder of said shank, then by engagement with said exposed cross section, separating said flange of said old split pin from the shank of said old split pin, removing said flange of said old split pin through said lower counterbore by exerting a downward force on said flange of said old split pin, and removing the remainder of said old split-pin assembly including said old nut and the remainder of said old split pin from the upper counterbore.