ULTRASONIC TEST PROCEDURE FOR EVALUATING FUEL CLAD ENDCAP WELD JOINTSOF PHWRS

This paper describes the application of ultrasonic test method and dig ital signal analysis techniques for the detection of fine defects of c ongruent to 10 percent of wall thickness in resistance welded endcap-c lad tube joints of fuel elements used in pressurized heavy water react ors (PHWRs). Standardization of test methodology was carried out using reference defects made on inner and outer surface of the weld region and subsequently, testing was carried out on a number of endcap weld j oints suspected to have natural defects which were rejected in the hel ium leak testing. The results obtained were further validated by destr uctive metallography thereby confirming the sensitivity and reliabilit y of the developed test methodology.