Westinghouse Electric Corporation

Westinghouse Electric Company LLC

John C Lichauer

Hassan J Ahmed

Qui V Le

Thomas W Nenno

Nicola G Arlia

Lawrence J Zana

John M Beatty

Kyle M Flanigan

Daniel C Wood

A method of employing an eddy current sensor to perform an inspection of a tube of a steam generator involves accelerating and decelerating the eddy current sensor in a predetermined fashion that substantially reduces the likelihood of damage to the eddy current sensor. The reduction of probe stresses reduces radiological waste and reduces radiation exposure to workers involved in changing damaged probes The recording of an eddy current signal at each of a plurality of equally spaced apart locations along the tube permits the velocity of the eddy current sensor to be varied without compromising the validity of the data that has been recorded. The inspection system employs an encoder that outputs a series of signals as the probe is advanced incremental distances within the tube of the steam generator, and eddy current sensor signals are recorded responsive to at least some of the signals from the encoder.

Position-based sampling for eddy current inspection of steam generator tubes

A non-contact surface flaw detection system for workpieces such as nuclear fuel pellets transports the pellets continuously along an illuminated path while rotating them. A line scan camera records a series of line scans for the pellets and the resulting values of pellet reflectivity are digitized. Pixel values are compared to thresholds defined adaptively by averaging and/or using a video finite impulse response filter, to generate a binary map of 'good' and 'bad' pixels, that also defines the edges of the pellet in the map. A processor counts and associates bad pixels to logically define and assess blobs of bad pixels. The processor checks for coincidence of the edge pixels with a nominal edge line that best fits the edge, for finding edge flaws. The pellets assessed in this manner are selected or rejected. Camera sensor elements are normalized for gain and offset. Shifting of the pixel data cancels skew produced in scanning moving pellets. Convolution filters cancel isolated bad pixels and enhance contrast at the edge. For processing adjacent areas, the pixel image of the pellets can be tiled, flaws bridging the tile boundaries being assessed as a single blob. The apparatus is preferably arranged for parallel pipeline processing for sidewall and edge defects and can be embodied in a series of modular VME boards.

Non-contact flaw detection for cylindrical nuclear fuel pellets

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Irwin, PA, United States of America

John C Lichauer