Evaluating the use of ultrasonic testing in lieu of radiography for inspecting welds in nuclear power plants

The nuclear power industry has recently proposed using ultrasonic testing (UT) in lieu of radiographic testing (RT) on new construction welds and on the repairs of operating reactor component welds. Advantages of UT include a reduction in inspection time, costs, and plant personnel exposure to radiation fields. The replacement of one nondestructive testing method with another, however, requires a detailed analysis of the capabilities of the replacement method as compared to the existing method. Capabilities of interest in this context include detection reliability, false call rates, flaw characterization and sizing accuracy, human factors, data recording capabilities, and cost. The interchangeability of UT and RT has been studied by several institutions, but the evidence found to date in a literature search is not conclusive and therefore requires further investigation to assess the ability of UT to meet nuclear power industry fabrication and pre-service inspection standards. This paper reviews relevant literature on the interchangeability of UT and RT, and identifies potential gaps that may need to be addressed in this area.