General Electric Company

David C Berg

Jack P Clark

Balasubramanian S Kowdley

James C Tung

David L Richardson

Jack Toshio Matsumoto

Thurman D Smith

A method and an apparatus for in situ ultrasonic inspection of the core spray T-box to thermal sleeve attachment weld and the core spray T-box to cover plate attachment weld in BWRs. The apparatus incorporates a stationary clamping mechanism and sliding and rotational mechanisms which are operated remotely to scan the transducer over the T-box welds and heat-affected zones thereof. The T-box weld inspection tool comprises the following assemblies: clamping jaws for clamping the tool onto the T-box arms in response to activation of a pair of pneumatic cylinders; a side slide stage having a transducer carriage which is slidable in parallel with the centerline axis of the thermal sleeve in response to activation of a first drive motor; a radial face stage having a transducer carriage which is slidable in a direction perpendicular to the centerline axis of the thermal sleeve in response to activation of a second drive motor; and a rotation stage which rotatably supports both the side slide stage and the radial face stage for rotation about the centerline axis of the thermal sleeve in response to activation of third and fourth drive motors, respectively. The transducers carried on the radial face stage are used to interrogate the T-box to cover plate attachment weld; the transducers carried on the side slide stage are used to interrogate both the T-box to cover plate and the T-box to thermal sleeve attachment welds.

Method and apparatus for remote ultrasonic inspection of core spray

An improved method for repair of incore-instrumentation-housing and related defects in a nuclear reactor system involves three stages, each with ultrasonically assisted inspections. In the first stage, a defective incore housing is removed and the exposed area and aperture at the former location of the incore housing is ultrasonically inspected using an ultrasonic probe with a tiltable disk-shaped head that self-conforms to the local contour of the reactor vessel bottom. In the second stage, a weld buildup is formed. The reactor is then sealed and the weld buildup is machined to define an aperture therethrough. The weld buildup is then ultrasonically inspected with a second probe with a centering member that is stationary as the probe body is moved vertically relative to it. In the third stage, a J-prep is formed. A new incore housing is inserted through the weld buildup aperture. The new incore housing is welded at the J-prep. The J-weld is ultrasonically inspected using a third ultrasonic probe. The new incore housing is then connected to the incore guide tube with shrink couplings, and reactor activity can be restored.

Ultrasonic probes for inspection of reactor pressure vessel bottom head

Repair of incore housings using ultrasonic examinations

An automated system for examining incore housing welds in a nuclear reactor from above is disclosed. The probe uses both ultrasonic and eddy current non-destructive inspection coils to examine the weld for indications, or flaws. It is inserted into the incore housing tube from above because of the high radiation exposure workers experienced using the prior method of inserting a probe into the incore housing from below. This is conveniently done when the incore flux monitors are removed during standard maintenance, and is performed from the refueling bridge.

Incore housing examination system

Growing community of inventors

San Jose, CA, United States of America

David C Berg