General Electric Company

Sierra Matrix, Inc.

Peter M Patterson

Jack P Clark

David L Richardson

Richard W Perry

Balasubramanian S Kowdley

Thurman D Smith

Marvin F Fleming

Scott R Stanton

An acoustic inspection device having a transducer housing opening to a face of the device to be disposed opposite a workpiece to be inspected. That face of the device having selectively located multi-piece flexible material of a selected length extending outward therefrom disposed to interface with the surface of the workpiece. A first portion of the flexible material is supplied to create, and surround, a region close to the opening of the transducer housing with a plurality of couplant supply ports around the transducer opening to form a chamber into which couplant is continuously supplied to couple the transducer to the surface of the workpiece. A second portion of the flexible material being spaced outward from, and surrounding, the first of the flexible material to create another chamber having vacuum ports in the face of the device opening into that chamber to recover couplant that leaks through the first portion of the flexible material from the couplant chamber. The flexible material is also provided to automatically locally adjust to the uneven surface of the workpiece while maintaining contact to that surface. To permit the use of the device in any orientation from horizontal, through various angles, to fully inverted, the couplant is provided independent of gravity feed with the vacuum being sufficient to recover the leaked couplant in any orientation of the device.

Apparatus for acoustic inspection of a workpiece in arbitrary scanning orientations

An apparatus and process for the remote inspection for stress corrosion cracking of welded shut boiling water reactor shroud access cover plates is disclosed. The apparatus consists of a streamline housing having a top side with lugs for the attachment of lowering lines on either end of the housing. Medially of the streamline housing and projecting downwardly from the bottom of the streamline housing, there is provided a central rotating pedestal with a rubber base. The rotating pedestal and rubber base enable the entire housing to rest on and rotate relative to the pedestal and rubber base. A first motor interior of the housing rotates the housing at a bevel gear rigidly mounted to the central pedestal. A second motor rotates a threaded shaft driving a ball screw with an attached mount for an ultrasound transducer. The mount and transducer responsive to rotation of the ball screw traverse along the elongate dimension of the housing over an opening through the bottom of the housing. A focused ultrasound transducer passes above the metal to be inspected. This ultrasound transducer focuses the sound through the water at an oblique angle to and from the metal of the hatch cover plate for an ultrasonic examination for stress corrosion cracking.

Apparatus for ultrasonic examination of BWR shroud access cover plate

In operation, the device is lowered with paired lines attached to both housing lugs but suspended under tension only from one line to one lug so that the streamline housing is vertically disposed. With the housing vertically disposed during lowering, obstacles can be avoided such as the guide rod for the steam separator and dryer as well as the feedwater and core spray spargers. When lowered to the vicinity of the ledge and cover plate to be inspected, the slack line is fished around any obstacle and thereafter placed under tension. The streamline housing is then lowered using both lines in a horizontal position so as to expose downwardly the pedestal and rubber foot. Lowering is completed with remote camera assistance. Sample sweeps with the ultrasound transducer of spaced apart sections of the cover plate weld are used for precise centering of the pedestal and rubber base with respect to the center of the cover plate. Repeatedly logging a longitudinal excursion of the ultrasound detector with indexed rotation of the housing permits scanning entirely around the weld of the cover plate. This enables remote ultrasound survey of the weld of the cover plate for stress corrosion cracking.

Ultrasonic examination of BWR shroud access cover plate retaining welds

In a boiling water reactor, an apparatus and process for ultrasound inspection of the top guide is disclosed. The top guide constitutes a lattice of stainless steel bars overlying the core plate and being assembled at confronting grooves with the lattice mounted at the side edges to the reactor pressure vessel. This lattice braces the upper ends of the vertically supported fuel assemblies in their requisite orientation and spaced apart relation to enable among other things the required spatial interval to be maintained for control rod moderation of the reaction. Because of the proximity of the top guide to the fuel assemblies, the individual bars making up the lattice need to be checked for cracking, especially that cracking produced by irradiation assisted stress crack corrosion. With a defined cell in the lattice emptied of its contained and adjoining fuel assemblies, there is disclosed an ultrasound test for cracking. A sound transducer on a first special frame sweeps horizontally across the top of a bar interrogating the bar with vertical ultrasound waves for detecting horizontal cracks. Similarly, a sound transducer on a second special frame sweeps vertically across the side of a bar interrogating the bar with angularly incident horizontal ultrasound waves for detecting vertical cracks. Nondestructive testing of the lattice assembly occurs without required disassembly.

Ultrasonic examination of reactor pressure vessel top guide

Apparatus for remotely controlled examination of the control rod drive penetration stub tubes in the wall of a nuclear reactor pressure vessel including a rotatable carriage on which is mounted a reciprocable shaft to which is attached an inspection instrument for scanning the stub tubes.

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Livermore, CA, United States of America

Peter M Patterson