Detection of degradation in new and aging PWR S/G's has progressed from bobbin coil technology in the 1960's to rotating coils and arrays that were developed in the early 1980's. The array probe was surpassed by the rotating coil technology because of the ability to handle and process the data from the rotating coils. A single coil rotated 360 degrees and was axially retracted or pushed at between 0.1 to 0.6 inches per second. The rotating coil technology currently supplements the bobbin coil examinations and provides a characterization of the flaw morphology. As steam generator degradation becomes more prevalent with age the use of techniques that are qualified for the degradation that have or could occur in the future must be addressed. The same holds true for the replacement steam generator inspection requirements. The need for faster inspection techniques capable of examining feet versus inches of tubing at and provide similar detection capabilities as demonstrated with rotating coil technology are a necessity. Faster computers have allowed the electronic rotation of coils without a physical rotating device. This is accomplished by placing the electronics in the head of the probe that allow for multiplexing a series of coils in a specific arrangement. The electronic rotational speed approaches approximately 30, 000 RPM. The processing and alignment of the data are performed by software to allow for a waterfall or color display as well as a lissajous response from the coil of interest.
This paper will describe the qualification work associated with the array probe pulled at 20 inches per second, as well as, examples of rotating coil comparisons to the array probe. Essential variables will be provided, along with the range of flaws used for the qualification.
