Abstract: A probabilistic method for optimizing the inspection of a heat exchanger that determines the maximum number of degraded tubes that can be permitted to remain in service for a contemplated interval of time without exceeding an allowable probability of a tube burst, based upon Extreme Value Probability Distribution theory. The method also determines the minimum number of tubes that need to be inspected to establish that no more than the determined maximum number of degraded tubes will be permitted to remain in service for the contemplated interval of time based upon Bayesian Acceptance Sampling Theory.

Abstract: A probabilistic method for optimizing the inspection of a heat exchanger that determines the maximum number of degraded tubes that can be permitted to remain in service for a contemplated interval of time without exceeding an allowable probability of a tube burst, based upon Extreme Value Probability Distribution theory. The method also determines the minimum number of tubes that need to be inspected to establish that no more than the determined maximum number of degraded tubes will be permitted to remain in service for the contemplated interval of time based upon Bayesian Acceptance Sampling Theory.

Abstract: Method of restricting transverse displacement of a nuclear heat exchanger tube support plate during a transient event, the support plate having a plurality of holes therethrough for passage of respective ones of a plurality of heat transfer tubes. The method includes radially expanding the tube adjacent the first side of the support plate to define a first expanded region thereat, the tube being expanded to a diameter greater than the diameter of the hole formed through the support plate. The method further includes radially expanding the tube adjacent the second side of the support plate to define a second expanded region thereat, the tube being expanded to a diameter greater than the diameter of the hole formed through the support plate. The first expanded region and the second expanded region coact to restrict transverse displacement of the support plate because the support plate is firmly captured between the first expanded region and the second expanded region.

Abstract: Tube plug and method for plugging a heat exchanger tube having an inner wall, which tube plug has a reduced susceptibility to stress corrosion cracking. The tube plug includes a shell having a closed end, an open end and an outer wall, the shell defining a chamber therein in communication with the open end of the shell. Disposed in the chamber is an expander member for expanding the outer wall of the shell into sealing engagement with the inner wall of the tube. A sealing member engages the expander member and is disposed across the open end of the shell for sealing the chamber defined by the shell so that fluid can not enter the chamber to corrosively attack the shell.

Abstract: System and method for in situ testing of the leak-tightness of a tubular member, which tubular member may be a nuclear steam generator heat transfer tube. The system includes a mandrel insertable into the tube, the mandrel having a pair of spaced-apart expandable bladders surrounding the mandrel. A first channel extends through the mandrel and is in communication with the bladders. A fluid supply circuit is in fluid communication with the first channel for supplying pressurized liquid to the bladders so that the bladders radially expand into sealing engagement with the inner diameter of the tube. As the bladders expand into sealing engagement with the tube, a sealed annular chamber is defined therebetween bounded by the bladders and the inner diameter of the tube.

Abstract: A fastener for fastening together a plurality of members, such as the plurality of members comprising a tube plug, and a method for plugging an opening in a solid member, which may be a tube, for preventing the flow of fluid through the opening in a solid member or through the tube, such as a nuclear steam generator tube, comprises a first member, such as a shell, a second member, such as a bolt, and locking structure. A deformable tab portion of the locking structure may have an undercut positioned so that when the second member is installed within the first member, a first surface of the undercut is bent toward a second surface of the undercut thereby plastically deforming the tab portion into a recess in at least one of the first and the second members for automatically securing together the plurality of members.

Abstract: An improved, easily removable plug for plugging the open end of a heat exchanger tube in a nuclear steam generator is disclosed herein. The plug generally comprises a cylindrical shell of Inconel.RTM. having tapered side walls, a closed end, an open end, a cork-shaped expander element disposed within the shell that radially expands the tapered side walls of the shell into sealing engagement with the inner walls of a tube when axially drawn from the closed to the open end of the shell, and a wall section in the interior of the shell between the closed end and the tapered side walls for receiving the expander element when this element is pushed back from the open end of the shell back against the closed end thereof, thereby affording clear mechanical access to the interior of the tapered side walls of the shell.

Abstract: A fastener structure for fastening together a plurality of members, such as the plurality of members comprising a tube plug, and a method for plugging an opening in a solid member, which may be a tube, for preventing the flow of fluid through the opening in a solid member or through the tube, such as a nuclear steam generator tube, comprises a first member, such as a shell, a second member, such as bolt structure, and locking structure. A deformable tab portion of the locking structure may have an undercut positioned so that when the second member is installed within the first member, a first surface of the undercut is bent toward a second surface of the undercut thereby plastically deforming the tab portion into a recess in at least one of the first and the second members for automatically securing together the plurality of members.

Abstract: A method of controlling leakage through degraded heat exchanger tubes in the tubesheet region of a nuclear steam generator is disclosed herein. The method comprises radially expanding a section of the heat exchanger tube disposed within the bore of the tubesheet into leak resistant engagement so that the resultant leakage flow is equal to or less than an acceptable leakage flow rate. The expanded, leak resistant section is located above the degraded section of the heat exchanger tube and below the upper side of the tubesheet. The length L of the leak resistant section and the pressure P necessary to create it are determined by ascertaining a plurality of combinations of length Lx and pressure Px that would result in a sufficiently tight engagement between the heat exchanger tube and the tubesheet bore to achieve the desired leakage flow rate, and by choosing a combination of Lx, Px that results in the smallest length L without exceeding a pressure of 50 ksi (344.7 MPa).

Abstract: An improved system for removing a plug from the open end of a heat exchanger tube in a nuclear steam generator is disclosed herein. It is particularly adapted for removing a plug formed from an elongated, cylindrical shell of Inconel.RTM. having a closed end, an open ends, and an expander element that radially expands the shell when axially drawn from the clossed to the open end of the shell. The system comprises an expander remover for axially pushing the expander element from the open end completely through the closed end of the plug shell, and a TIG torch for creating beads along the longitudinal axis of the plug shell which relax the engagement between the plug shell and the tube after the weld beams harden. Finally, the system includes a plug puller for pulling the loosened plug from the tube.

Abstract: The multi-seal tube plug comprises a substantially cylindrical sheath closed at one end and having a central cavity. An expander is received within the central cavity of the sheath and acts to expand the sheath into contact with the tube. The expander comprises a plurality of radially expandable disks having a central aperture and an expander member adapted to be received within the aperture and to expand the disks. The expanded disks expand a portion of the sheath into contact with the tube to sealingly engage the tube. The expander member is preferably conical and interacts with the conical inner surfaces of the disks. An alternate embodiment of the multi-seal tube plug uses conical washers rather than radially expandable flat disks. All embodiments of the multi-seal tube plug are easily removable and do not damage the tube.

Abstract: The multi-seal tube plug comprises a substantially cylindrical sheath closed at one end and having a central cavity. An expander is received within the central cavity of the sheath and acts to expand the sheath into contact with the tube. The expander comprises a plurality of radially expandable disks having a central aperture and an expander member adapted to be received within the aperture and to expand the disks. The expanded disks expand a portion of the sheath into contact with the tube to sealingly engage the tube. The expander member is preferably conical and interacts with the conical inner surfaces of the disks. An alternate embodiment of the multi-seal tube plug uses conical washers rather than radially expandable flat disks. All embodiments of the multi-seal tube plug are easily removable and do not damage the tube.

Abstract: The tube plug comprises a substantially cylindrical sheath closed at one end and having a relatively smooth outer surface and a central cavity. An expandable shell is received within the central cavity of the sheath. An expander member is adapted to expand the shell from within by being axially translated within the shell, the expander member also being adapted to grip the inner surface of the shell to retain the expander member in the expanded position. The outside surface of the shell is preferably provided with a plurality of lands. A second embodiment of the tube plug comprises a sleeve, a closed shell member adapted to be inserted within the sleeve, and an expander member contained within the shell. Upon axial translation of the expander member within the shell, the shell is expanded into contact with the sleeve and the sleeve is expanded into contact with the tube, thereby sealing the tube.