Innovative Ultrasonic Testing (UT) of Nuclear Components by Sampling Phased Array with 3D Visualization of Inspection Results

摘要

Unlike other industrial branches, nuclear industry - when performing UT – is not only asking for a reliable detection, but also for an exact sizing of material defects. Under these objectives ultrasonic imaging plays an important role in practical testing of nuclear components in the data evaluation process as well as for documentation of the inspection results. 2D and 3D sound-field steering by means of phased array technology offers great opportunities for spatially correct visualization of ultrasonic indications. Thus, by the use of modern phased array inspection systems, UT of objects with complex geometries can be performed more effectively and flexibly. Tomographic reconstruction methods, e.g. Synthetic Aperture Focusing Technique, can significantly improve the spatial resolution of UT indications and allow as best possible prediction of the quantitative evaluation of the defect size. However, this reconstruction technique has not been wide use in practice in the past due to its effort in numerical computing and processing time especially when 3D-reconstruction is asked for. The Fraunhofer Institute for Non-Destructive Testing - IZFP has recently developed the Sampling Phased Array technology (SPA), which combines both Phased Array and SAFT techniques. One of the advantages of the SPA-approach is that the real-time three-dimensional visualization of the inspection volume with on-line quantitative evaluation of the inspection findings. The current report demonstrates and discusses the potential of spatial imaging for accurate defect sizing, especially when welds in thick walled nuclear components are inspected. The present work was aided by Federal Ministry of Economics and Technology based on resolution of German Bundestag in scope of the project No. 1501344 of GRS (Gesellschaft fur Reaktorsicherheit) "Improving the Inspectability and Analysis of Indications by Ultrasonic Testing of Nuclear Components".