An improved system for cleaning the upper bundle region of pressurized water reactor steam generators is now available. This system employs high pressure water jets to remove sludge and scale from tube and support plate surfaces and from the broach holes throughout the upper bundle region of steam generators. Benefits of sludge removal can include mitigation of the corrosion process, improvement of plant performance and increased operational stability. The cleaning equipment is installed through existing handholes in the tubesheet region and accesses the upper bundle through flow slots in the tube support plates. The system includes a Bulk Cleaning Head which directs high pressure water jets into the tube bundle, a Vertical Deployment System which delivers and positions the head at the desired locations in the upper bundle region, and a high pressure water pumping and sludge processing system. This paper describes the system, several key
components, overall system operation, safety issues, and field use chronology. Specific performance issues that are discussed include the cleaning coverage achieved, the time required to clean a steam
generator, and cleaning effectiveness. The Upper Bundle Hydraulic Cleaning System described in this paper is available for use in several types of steam generators. Keywords: steam generator, sludge lancing, high pressure water jetting, fouling, UBHC, stress corrosion cracking