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US 4,406,856 AGranted
Removal of portions of tubes from steam generator of nuclear reactor
AssigneeWestinghouse Electric Corp.
InventorsRobert L. Wilkins, Charles F. Williams
Life of this patent
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AssigneeWestinghouse Electric Corp.
InventorsRobert L. Wilkins, Charles F. Williams
Estimating the term…
After the tube portion to be removed is severed from the remainder of the U-tube and its weld to the header is machined off, the internal surface of the portion is engaged internally by an ID gripper and pulled out of the header. Then the external surface is engaged by an OD gripper and pulled further out of the header. The first tube length is pulled out as far as the space under the header permits and is then cut off. Successive lengths are likewise pulled out and cut off. The apparatus for accomplishing this object includes a base secured to the header by expanded mandrel mechanisms. A carriage is suspended from the base on screws which are driven by a motor to move the carriage away from and towards the base. An OD gripper assembly is suspended from the carriage and is movable by fluoroactuated piston rods away from and towards the carriage. An ID gripper assembly extends through the OD gripper assembly. The gripper of the ID assembly is actuable to engage the internal surface of the tube portion. With its gripper so engaged the ID assembly is engaged by the gripper of the OD assembly and the engaged tube portion is pulled out of the header by the OD assembly. The ID gripper is then disengaged and the OD gripper is engaged with the tube portion in the same way that it engages the ID assembly and the tube portion is pulled out further. The apparatus also includes a tube cutter having an abrasive wheel. The wheel cuts the lengths of the tube portion at an angle so that for examination and testing the tube lengths can be matched and the orientation of any defect with respect to the plate in the steam generator which separates the inlet and outlet ends of the tubes and the U-tube supports can be identified.
Apparatus for removing portions of tubes from a steam generator of a nuclear reactor, said steam generator including a header having openings into which said tubes extend from within said generator, the said apparatus including a base plate, means securing said base plate to the face of said header opposite to the face from which said tubes extend, the said base plate being secured at a location of said header where a portion of a tube to be removed is readily accessible, a carriage suspended from said base plate movable towards and away from said base plate, means connected to said carriage, for moving said carriage away from and towards said base plate, gripper means for gripping the external surface of the portion of the tube to be removed suspended from said carriage, movable away from and towards said carriage, said gripper means including a gripper and mechanism for actuating said gripper to engage and be disengaged from the outside surface of said portion to be removed, and means connected to said external-surface gripper means for moving said external-surface gripper means away from and towards said carriage.
Apparatus for removing portions of tubes from a steam generator of a nuclear reactor, said steam generator including a header having openings into which said tubes extend from within said generator, the said apparatus including gripper means for gripping the internal surface of the portion of a tube to be removed, the said internal-surface gripper means including a first gripper, means, connected to said first gripper for actuating said first gripper to engage the internal surface of said portion of a tube to be removed from said generator, gripper means for gripping the external surface of the portion of a tube to be removed, the said external-surface gripper means including a second gripper, means connected to said second gripper, for actuating said second gripper to engage the external surface of said portion to be removed, and means, connected to said internal-surface gripper means and to said external-surface gripper means for actuating said internal-surface gripper means to pull said portion to be removed out of said header while said first gripper is engaged with the internal surface of said portion and for actuating said external-surface gripper means to pull said portion to be removed a predetermined distance out of said header while said second gripper is engaged with the external surface of said portion.
Apparatus for removing portions of tubes from a steam generator of a nuclear reactor, said steam generator including a header into which said tubes extends means suspended from said header for pulling a portion of a tube to be removed from said header, and means, also suspended from said header, for severing said portion from the remainder of said tube, the said severing means including a cutting wheel disposed so as to cut said portion from said tube at an angle whereby when a plurality of portions of a tube are pulled out and severed, the formation of the length of the tube by the joining of said tube portions in their original succession is facilitated.
The method of processing the tubes of a steam generator of a nuclear reactor, said tubes extending into and being welded to a header and being supported by tube-support plates along their length, the said method comprising inserting an eddy-current probe into a plurality of selected of said tubes, to detect a defective tube, severing that portion of a tube, detected to be defective, at a position along said tube that is a predetermined distance below that tube support plate which is above the detected defective region of the tube and a predetermined distance above the said defective region, severing the weld to said header of said portion, removing the said portion by engaging first the internal surface of said portion and pulling the said portion out of the header a predetermined distance and then engaging the external surface of said portion and pulling the portion out of a further predetermined distance, and examining the portion.
The method of removing a portion of a U-tube, whose outer ends extend into a header, from the steam generator of a nuclear reactor, with apparatus including a gripper assembly for gripping the internal surface of said portion of said tube and a gripper assembly for gripping the external surface of said portion, the said method comprising operating said internal-surface gripper assembly manually at the start only of a tube-portion removal operation to actuate the internal-surface gripper to engage the internal surface near the outer end of the tube portion and to pull said end from said header, and thereafter operating said external-surface gripper assembly only by remote control to remove the tube portion completely from said steam generator.
Dependencies are inferred from the claim text.