Westinghouse Electric Corporation

Electric Power Research Institute Incorporated

William C Ritz

Robert D Burack

Paolo R Zafred

David A Snyder

John B Gunter

John E Sharbaugh

Joseph M Kazan

Charles E Lutz

A nozzle dam assembly for closing off a nozzle of a steam generator and a process for remotely positioning such nozzle dam are disclosed. The nozzle dam includes a mounting ring mounted on an inner surface of the steam generator about a periphery of an inner opening of the nozzle, at least one substantially planar central section and two substantially planar side sections together forming a substantially planar surface, the surface being of a greater diameter than the inner opening of the nozzle. Securing devices are also provided for securing each of the sections to the mounting ring after all the sections are positioned over the inner opening of the nozzle. Also provided is a sealing gasket which is secured to the central section with the sealing gasket having a diameter substantially equal to a diameter of the substantially planar surface formed by the sections for forming a fluid tight seal between a periphery of the substantially planar surface and the inner surface of the steam generator about the periphery of the inner opening of the nozzle. Each of the sections are initially passed through the manway of the steam generator. Once inside the channel head of the nuclear steam generator, the central section of the nozzle dam is retrieved by a robotic arm and positioned over a central portion of the nozzle opening. The robotic arm then positions the remaining side sections over the opening. Once each of the sections are aligned and positioned on the mounting ring, a bolt torque mechanism is then attached to the robotic arm and integral hold down bolts of the sections are sequentially tightened.

Steam generator nozzle dam

Disclosed is a system for driving inspection probes through steam generator tubes of a nuclear power plant, particularly eddy current probes. The system utilizes a single conduit that is connectable to the tube sheet of a steam generator and comprises a multiple-unit probe pusher having a housing containing a plurality of independently actuable drive paths, a multiple-unit probe storage device including a plurality of independently movable take-up reels, and a guide or deflector device for directing any one probe that is driven from any one of the drive paths of the probe pusher to the single conduit. Preferably, the entire system is also remotely controllable. The system enables one probe to be in use for tube inspection while providing readily available spare probes to replace a defective probe with a minimum of downtime and worker radiation exposure.

Multiple-unit probe pusher and system for driving eddy current

An apparatus and process for positioning and for simultaneously oscillating a plurality of heater probes within a plurality of heat exchanger tubes mounted in a tubesheet of a nuclear steam generator is disclosed herein. The apparatus generally comprises a frame, a plurality of probe drivers mounted onto the frame, wherein each driver includes a pneumatically operated, bladder-type gripper for selectively gripping and ungripping the push-cable of one of the heater probes, as well as an oscillating mechanism powered by a variable voltage d.c. motor. A controller connected between the d.c. motor and a power source separately controls the frequency and the amplitude of the cycle that the oscillating mechanism moves the gripper in, and further controls the alignment between the midpoint of the oscillatory cycle and a selected point along the longitudinal axis of the tube. The apparatus is movable to a selected position on the tubesheet by means of a robotic arm, and includes a coupling for remotely attaching and detaching the arm from the frame of the apparatus. The frame of the apparatus includes a pair of opposing cam-locks for detachably securing the apparatus at a selected position on the tubesheet, thereby advantageously freeing the robotic arm that delivered the apparatus. Finally, the frame is contoured to the shape of the inner walls of the steam generator so that the apparatus can service heat exchanger tubes located on the periphery of the tubesheet.

Apparatus and process for simultaneously positioning and oscillating a

Both a system and method for simultaneously heat treating a plurality of heat exchanger tubes in the tubesheet of a steam generator are disclosed herein. The system generally comprises a plurality of heater probes receivable within the open ends of the tubes, each of which has a bladder means for detachably securing the probe within the tube, a plurality of hose-like probe guide assemblies positionable over the open ends of the tubes for guiding the heater probes into the tubes, and an end effector having a cup-shaped coupler connected to a robotic arm for delivering the probe guide assemblies over the open ends of different tubes. The ability of each of the heater probes to detachably mount itself into proper position within its respective heat exchanger tubes advantageously frees up the robotic arm so that it can quickly and sequentially install a number of probe guide assemblies and heater probes in different locations within the tubesheet. Because the probe guide assembly installation time is a relatively small part of the entire heat-treating operation of a single tube, the system and method of the invention allows a plurality of non-adjacent tubes to be substantially simultaneously heat treated, thereby advantageously shortening the total amount of time necessary to perform the heat-treatment maintenance operation.

System and method for stress-relief of welds in heat exchanger tubes

A nuclear reactor refueling system for a liquid metal-cooled fast breeder reactor includes a large rotatable plug (18) eccentrically mounted relative to the reactor core (12), and a small rotatable plug (24) mounted within the large plug (18). A fuel handling machine (28) is rotatably mounted upon the small plug (24), and the eccentric mounting of the large plug (18) permits the fuel handling machine (28) to access all areas of the reactor core (12) as well as a fuel transfer station or port (34) located externally of the reactor core barrel (16) yet internally of the reactor pressure vessel. A unique six-fingered star-shaped upper internals structure (36) is eccentrically mounted upon the large plug (18) so as to be concentrically disposed relative to the core (12) when the reactor is in operation yet permitting access to the central-most fuel assemblies (14) of the core (12) as the large rotatable plug (18) is rotated during refueling operations. The uniquely configured upper internals structure (36 ), as well as the eccentric mounting of the large plug (18) relative to the core barrel (16) and the provision of the small plug (24) eccentrically mounted upon the large plug (18) permits the diametrical extent of the large plug (18) to be precisely the same as that of the core barrel (16).

Refueling system with small diameter rotatable plugs

A combination seal and bearing arrangement for use in a nuclear reactor including a vessel and vessel cover is disclosed herein. The vessel cover itself includes at least one rotatable plug which serves to perform certain position related functions within the reactor vessel and the combination seal and bearing arrangement is provided for sealing the annular opening around the rotation plug while, at the same time, providing a bearing support for the latter.

Growing community of inventors

Greensburg, PA, United States of America

William C Ritz