IN-SITU OPTICAL PROFILOMETRY OF CANDU FUEL CHANNELS

摘要

Detailed knowledge of flaw geometry is crucial in the stress analysis of flaws found in the thin-walled Zirconium alloy pressure tubes of CANDU reactors. While ultrasonic inspection can provide much of the required data, the measurement of the sharpness, or root-radius, at the bottom of a flaw has not so far been possible in-situ. This paper will describe the application of optical profilometry techniques, to measure directly the depth and root-radius of open inside-surface flaws, within a flooded reactor pressure tube. The tool uses a rad-tolerant television camera, custom optics and light stripe generators to collect digitized image data from three different views of a flaw. Software has been developed to manage the collection of the image data and provide a full range of display and automated analysis options. The tool has recently been used successfully to measure fretting flaws in the 100-250 micron deep range.