Abstract: A means of offsetting semi-circular tube support plates typically present in heat exchangers with cross flow baffles, such as axial flow economizers, utilizing the motive force of steam generator pressurization. The offset slightly flexes the tubes, thereby providing a preload which minimizes the potential for tube vibration and wear.

Abstract: A tube and shell steam generator having an anti-clogging heat exchange tube bundle wherein the tube support plates within the tube bundle are designed with varying degrees of porosity thereby regulating local secondary side fluid conditions (velocity, quality, superheat, void fraction, etc.) in a manner to reduce the potential for clogging of the tube support plate lobes that are more prone to clogging.

Abstract: A tube and shell steam generator in which a series of rods having a diameter substantially equal to that of the heat exchange tubing in the tube bundle are placed on either side of the tube lane to buffer the flow in the tube lane from the heat exchange tubes to attenuate turbulent forces on the first several rows of heat exchange tubes adjacent to the tube lane.

Abstract: A feedring for use with an axial flow preheat steam generator which utilizes a double wrapper to direct feedwater flow to the cold leg tube bundle region. The feedring is positioned directly over the double wrapper and includes a plurality of standpipes spaced circumferentially along the feedring. The standpipes respectively extend vertically from a lower portion of an interior of the feedring upward through the interior of the feedring. The standpipes have a feedwater intake in the upper portion of the feedring to minimize the potential for vapor formation and bubble collapse water hammer. The components of the standpipe are arranged to minimize the transmission of entrained loose parts from traveling with the feedwater to the tube bundle. A feedwater discharge is provided at the exit of the standpipe at or below the bottom of the feedring, for evenly distributing the feedwater into the double wrapper downcomer.

Abstract: A steam nozzle flow restrictor for a steam generator that restricts steam exit flow during a steam line break, but has a low pressure drop during normal operation. The flow restrictor has a support web suspended from the steam outlet nozzle with the web having a central opening concentric with the central axis of the nozzle. A shaft is slidably supported within the central opening of the web and has an orifice plate that is suspended within the steam generator at one end of the shaft, spaced from the steam nozzle. The orifice plate closes against the underside of the nozzle upon encountering increased steam exit flow as a result of a steam line break.

Abstract: A steam generator includes a tube bundle having a plurality of tubes, arranged in rows and columns. The first column of tubes includes a first tube having a curved center line disposed in a first plane. The second column of tubes includes a second tube having a curved center line disposed in a second plane, the second plane being parallel to and spaced a distance from the first plane. The steam generator further includes a first number of solid anti-vibration bars disposed between the first column of tubes and the second column of tubes; wherein each of the tubes has a tube outer diameter; and wherein each of the first number of anti-vibration bars has a thickness generally transverse to the first and second planes, the thickness being greater than the distance between the first and second planes minus the tube outer diameter.

Abstract: A thermal sleeve is mechanically attached to the bore of a surge nozzle of a pressurizer for the primary circuit of a pressurized water reactor steam generating system. The thermal sleeve is attached with a series of keys and slots which maintain the thermal sleeve centered in the nozzle while permitting thermal growth and restricting flow between the sleeve and the interior wall of the nozzle.

Abstract: A locking mechanism for securing hatches internal to a steam generator that is made up of only mechanical locking elements with fully captured moving parts. The mechanism employs a locking pin with redundant mechanisms to secure the pin in the closed position. The moving parts of the device can be attached directly to a removable hatch so that installation and repairs that may be required can be performed outside of the pressure vessel of the steam generator.

Abstract: A feedring for use with an axial flow preheat steam generator which utilizes a double wrapper to direct feedwater flow to the cold leg tube bundle region. The feedring is positioned directly over the double wrapper and includes a plurality of standpipes spaced circumferentially along the feedring. The standpipes respectively extend vertically from a lower portion of an interior of the feedring upward through the interior of the feedring. The standpipes have a feedwater intake in the upper portion of the feedring to minimize the potential for vapor formation and bubble collapse water hammer. The components of the standpipe are arranged to minimize the transmission of entrained loose parts from traveling with the feedwater to the tube bundle. A feedwater discharge is provided at the exit of the standpipe at or below the bottom of the feedring, for evenly distributing the feedwater into the double wrapper downcomer.

Abstract: An automated tool and method for spacing a gap between the anti-vibration bars and the flow tubing in the bend region of a tube bundle of a U-tube steam generator, prior to welding, during manufacture. The tool comprises two toggle clamp elements attached to a scissors assembly, which are actuated by a linear drive motor in line with a force gauge, and coupled to a distance measuring device. The tool is operated by first attaching the toggle clamps respectively to two adjacent anti-vibration bars. A linear drive motor on the tool is then cycled and readouts of force and distance are plotted on a curve to determine the point of contact between the anti-vibration bar and the tube. The computer then automatically cycles the drive motor to adjust the gap to a desired range of position coordinates adjacent the point at which the curve markedly changes slope.

Abstract: A tube and shell steam generator having an anti-clogging heat exchange tube bundle wherein the tube support plates within the tube bundle are designed with varying degrees of porosity thereby regulating local secondary side fluid conditions (velocity, quality, superheat, void fraction, etc.) in a manner to reduce the potential for clogging of the tube support plate lobes that are more prone to clogging.

Abstract: A steam nozzle flow restrictor for a steam generator that restricts steam exit flow during a steam line break, but has a low pressure drop during normal operation. The flow restrictor has a support web suspended from the steam outlet nozzle with the web having a central opening concentric with the central axis of the nozzle. A shaft is slidably supported within the central opening of the web and has an orifice plate that is suspended within the steam generator at one end of the shaft, spaced from the steam nozzle. The orifice plate closes against the underside of the nozzle upon encountering increased steam exit flow as a result of a steam line break.

Abstract: An automated tool and method for spacing a gap between the anti-vibration bars and the flow tubing in the bend region of a tube bundle of a U-tube steam generator, prior to welding, during manufacture. The tool comprises two toggle clamp elements attached to a scissors assembly, which are actuated by a linear drive motor in line with a force gauge, and coupled to a distance measuring device. The tool is operated by first attaching the toggle clamps respectively to two adjacent anti-vibration bars. A linear drive motor on the tool is then cycled and readouts of force and distance are plotted on a curve to determine the point of contact between the anti-vibration bar and the tube. The computer then automatically cycles the drive motor to adjust the gap to a desired range of position coordinates adjacent the point at which the curve markedly changes slope.

Abstract: A tube and shell steam generator in which a series of rods having a diameter substantially equal to that of the heat exchange tubing in the tube bundle are placed on either side of the tube lane to buffer the flow in the tube lane from the heat exchange tubes to attenuate turbulent forces on the first several rows of heat exchange tubes adjacent to the tube lane.

Abstract: A means of offsetting semi-circular tube support plates typically present in heat exchangers with cross flow baffles, such as axial flow economizers, utilizing the motive force of steam generator pressurization. The offset slightly flexes the tubes, thereby providing a preload which minimizes the potential for tube vibration and wear.

Abstract: A thermal sleeve is mechanically attached to the bore of a surge nozzle of a pressurizer for the primary circuit of a pressurized water reactor steam generating system. The thermal sleeve is attached with a series of keys and slots which maintain the thermal sleeve centered in the nozzle while permitting thermal growth and restricting flow between the sleeve and the interior wall of the nozzle.

Abstract: A locking mechanism for securing hatches internal to a steam generator that is made up of only mechanical locking elements with fully captured moving parts. The mechanism employs a locking pin with redundant mechanisms to secure the pin in the closed position. The moving parts of the device can be attached directly to a removable hatch so that installation and repairs that may be required can be performed outside of the pressure vessel of the steam generator.

Abstract: A loose parts collection weir that is a nearly cylindrical structure that is integrally attached to the lower deck plate or sludge collector top plate of a steam generator to retain loose parts along the feedwater and recirculation water transit path to the tube bundle. The weir is a near vertical structure built into the upper drum of the steam generator, near the periphery of the lower deck plate or sludge collector top plate in the vicinity of the downcomer annulus. The weir may contain a radially inwardly projecting lip which forms a pocket for loose parts to collect. As the feedwater flows toward the downcomer annulus, loose parts will tend to deposit onto the lower deck plate aided by gravity and be trapped by the loose parts collection weir.

Abstract: A loose parts collection weir that is a nearly cylindrical structure that is integrally attached to the lower deck plate or sludge collector top plate of a steam generator to retain loose parts along the feedwater and recirculation water transit path to the tube bundle. The weir is a near vertical structure built into the upper drum of the steam generator, near the periphery of the lower deck plate or sludge collector top plate in the vicinity of the downcomer annulus. The weir may contain a radially inwardly projecting lip which forms a pocket for loose parts to collect. As the feedwater flows toward the downcomer annulus, loose parts will tend to deposit onto the lower deck plate aided by gravity and be trapped by the loose parts collection weir.

Abstract: Apparatus for attenuating vibration of a tube includes a cable disposed in the tube and spaced-apart attenuating assemblies mounted on the cable for frictionally engaging the wall of the tube in order to damp vibration of the tube. The assemblies also add rigidity to the tube in order to stabilize the tube against vibration. Each attenuating assembly comprises two spaced-apart end fittings mounted on the cable. A heat vaporizable insert is interposed between the end fittings for maintaining the end fittings in their spaced-apart relationship until the insert vaporizes. A preloaded coiled spring, which interconnects the end fittings and surrounds the insert, biases the end fittings towards each other after the insert vaporizes. A tubular, flexible and braided sheath, which is interposed between the end fittings, surrounds the spring and has respective ends thereof attached to the end fittings. When the insert vaporizes, the spring biases the end fittings closer together, thereby axially shortening the sheath.