Westinghouse Electric Corporation

Richard D Franklin

David E Murray

Gregg D Auld

Dennis J Cadwell

Albert R Vaia

Thomas E Dunn

John J Lescisin

An apparatus for loosening and removing sludge and other impurities from the interior of a heat exchanger vessel which may be the secondary side of a nuclear steam generator is disclosed herein. The apparatus generally comprises a nozzle having a first end that is detachably mountable into an access opening such as a sludge lance port in the secondary side of the generator, and a second end that extends into the interior of the secondary side at a 30 degree downward angle relative to the tubesheet in the vessel for minimizing the stresses applied to the heat exchanger tubes, and for uniformly reflecting the pulse back up toward the upper portions of the secondary side. A pulse generator is operably connected to the nozzle which has a controller for controlling the power level of the pulses generated. To further minimize such peak tube stresses, the pulse generator includes a pulse flattener, and the second end of the nozzle is aligned down the main tube lane.

Pressure pulse cleaning apparatus

Method is disclosed herein for removing debris from nuclear fuel assemblies which have been in service in a nuclear reactor. The method generally comprising immersing the fuel assembly in a pool of water which may be the cask loading pit of a nuclear facility, securing the fuel assembly in a spent fuel rack, enveloping the spent fuel rack in a rectangular sleeve in order to isolate the water surrounding the fuel assembly from the balance of the water in the cask loading pit, and discharging a series of pressure pulses into the isolated water from a pressure pulse source to create shock waves that exert momentary forces on the fuel rods sufficient to dislodge debris therefrom but insufficient to create a liftoff between the fuel rods and the spring fingers of the grids which retain them within the fuel assembly.

Pressure pulse method for removing debris from nuclear fuel assemblies

Both a system and a method for removing sludge and debris from the interior of the secondary side of a nuclear steam generator is disclosed. The method comprises the steps of introducing a sufficient amount of water in the secondary side to submerge at least the tubesheet, generating a succession of shock waves in the water by means of pulses of pressurized gas to create shock waves that loosen the sludge and debris, and vertically flushing the interior of the secondary side by suctioning water off from the bottom portion of the steam generator while simultaneously forcefully spraying water from the top portion of the generator over the bundle of heat exchanger tubes in order to remove the sludge and debris loosened by the shock waves. To conserve the water used in the flushing operation, the water that is suctioned off from the bottom portion of the steam generator is filtered and de-ionized and re-introduced through hoses at the top portion of the generator which forcefully directs water downwardly through the bundle of heat exchanger tubes and against the tubesheet. The invention greatly enhances the effectiveness of pressure pulse, water slap and water cannon cleaning methods in the secondary sides of nuclear steam generators.

System and method for vertically flushing a steam generator during a

A method for loosening and removing sludge and debris from the vessel of a heat exchanger, such as the secondary side of a nuclear steam generator, is disclosed herein. The method generally comprises the steps of providing a sufficient volume of a liquid, such as water, into the steam generator so that the lower portion which includes the tubesheet is submerged, and then generating a succession of pressure pulses within the water from one or more pressure pulse generators wherein each pressure pulse creates shock waves that exert momentary forces throughout the submerged portion of the generator of a magnitude sufficient to loosen the sludge and debris, but safely below the yield and fatigue limits of the heat exchanger tubes and other components within the generator. The pressure pulses commence as soon as a sufficient amount of water is introduced into the steam generator to submerge the tubesheet, and continue all the way through the draining of the steam generator.

Pressure pulse cleaning method

Both a method and system are disclosed herein for removing debris from nuclear fuel assemblies which have been in service in a nuclear reactor. The method generally comprising immersing the fuel assembly in a pool of water which may be the cask loading pit of a nuclear facility, securing the fuel assembly in a spent fuel rack, enveloping the spent fuel rack in a rectangular sleeve in order to isolate the water surrounding the fuel assembly from the balance of the water in the cask loading pit, and discharging a series of pressure pulses into the isolated water from a pressure pulse source to create shock waves that exert momentary forces on the fuel rods sufficient to dislodge debris therefrom but insufficient to create a liftoff between the fuel rods and the spring fingers of the grids which retain them within the fuel assembly.

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Jeannette, PA, United States of America

Richard D Franklin