PhD student, 2016/17 intake

University: University of Bristol

Industrial Partner: Fraser Nash Consultancy

Background:  Undergraduate Master’s in Physics, University of Bath (2016)

2D Phased Arrays for Improved Defect Detection and Characterisation in 3D Geometries in Nuclear Components

This PhD project focuses on the use of 2D phased arrays to improve NDT inspections of complex 3D geometries in nuclear components. Traditionally, volumetric inspections using a 1D array involve placing the array at multiple locations and stitching the resulting images together, or by generating multi-view images. This makes for a challenging and time-consuming process. A proposed solution is to use 2D arrays to not only reduce inspection times but also to improve defect image resolution by exploiting their ability to focus through surfaces that are curved in multiple directions.

This technique utilises the data acquisition method full matrix capture (FMC), followed by the total focusing method (TFM) imaging algorithm. The benefits of using ultrasonic arrays in FMC mode is well-established in several industrial sectors, where a number of FMC-based inspections using 1D arrays have been qualified. It has been demonstrated that 2D arrays could be employed to improve defect characterisation, including many defect types relevant for nuclear applications. Additionally, when 2D arrays are used in immersion they have the unique ability to image through non-planar surfaces, such as those found in pipework nozzles and other critical components. In these cases, the surface needs to be extracted and compensated for in order to image the interior of the component. The research will include modelling to conduct multi-parameter and defect sensitivity studies.

The extension of FMC and TFM to 2D arrays in this project will enable the inspection of components with more complex geometries.

3D TFM images of 3 bottom-drilled holes imaged in immersion through a planar surface