Differences in indications of different artificially produced flaws in non-destructive examination

Qualification of non-destructive examination procedures for in-service inspections of nuclear power plant components is performed using different types of artificial flaws. The assessment of the reliability of a procedure requires sufficiently representative flaws compared to the real service-induced flaws. Fatigue cracks can nowadays be produced artificially as thermal fatigue or mechanical fatigue cracks. Thermal fatigue crack production is very well controlled in matter of size and opening. That kind of cracks are very realistic option compared to the real service-induced cracks. Mechanical fatigue crack production is well known and widely used method and can produce very realistic cracks as well. Ultrasonic indications are highly dependent on defect characteristics like roughness, crack opening, tilt and branching. This work studies the influence of different reflector properties on flaw indications. Two kinds of artificial cracks from different manufactures and one EDM reference notch were made in austenitic stainless steel test blocks. Flaws were examined using phased array ultrasonic testing (PAUT), scanning acoustic microscope (SAM) and time-of- flight diffraction (TOFD) techniques. Flaw images produced by two digital radiography techniques are used as reference. The aim of the study is to get a wider perspective to the differences in similar type of flaws from different manufacturers