Project Outline

Efficient energy generation is a key component of meeting the low CO₂ emission goals outlined by the government and is reflected in the present technology priority. This project will address specific technological goals defined by the utilities who have numerous dissimilar metal joints in current operation. It also incorporates innovative and novel materials for phased array probe manufacture, quantification of microstructural data and validation of advanced modelling; this addresses the key priority to focus on advancing the technology base of the UK. To increase the efficiency and safety of future nuclear power plants, advanced materials and joining techniques have been proposed; these materials will need to perform in high stress, corrosive and irradiating environments. It is imperative to improve current inspection capabilities. Dissimilar metal joints are used in the primary circuit of nuclear power plants - eg the safe end weld between the ferritic (clad) reactor pressure vessel and the stainless steel cooling pipes. The ability to design the components for a high stress, high temperature environment through Engineering Critical Assessment (ECA) depends directly on the ability of the inspection techniques to detect and accurately size the specified defects. This project will overcome the difficulties of inspecting the inhomogeneous and anisotropic austenitic welds by fully accounting for the propagation of the ultrasound through the weld metal as well as implementing advanced phased array based focusing techniques to improve the signal to noise ratio. The strategies developed in this project, aimed towards the nuclear industry, will also be applicable to the oil and gas industry where the use of dissimilar metal joints is becoming widespread.

The ultimate aim of this project is to allow designers to specify high performance dissimilar metal joints confident in the ability of inspection to accurately detect, position and size the smallest possible crack like flaws. DMJs have a variety of flaws but crack like flaws pose the greatest threat to integrity, with catastrophic consequences due to failure of these joints. The present project primarily targets the safe-end weld configuration of current and future nuclear power plants and the clad pipelines of the oil/gas industry. Hence, given the corrosive, irradiating, high temperature environment within which a DMJ maybe installed in a nuclear utility, the quality of their inspection has a direct bearing upon the safety of personnel as well as the general public at large.