Development of In-service Inspection techniques for nuclear power plants in India

Abstract

Nondestructive Evaluation (NDE) plays a major role in ensuring the safe and reliable operation of Pressurised Heavy Water Reactors (PHWRs) which are the mainstays of the nuclear power programme in India. This paper discusses the significant developments made over the last two decades which have contributed towards establishing novel methodologies and techniques for In-service Inspection (ISI). The techniques covered are broadly divided into two classes viz. (a) magnetic and electromagnetic, (b) acoustic techniques. Techniques discussed under the first category include eddy current testing (along with the various developments linked with it such as the remote field eddy current testing, eddy current imaging and the phased array eddy current testing), Magnetic Barkhausen Noise and Infrared Imaging. Under the second category, the emphasis is on ultrasonics (for defect detection with high sensitivity and for characterisation of microstructures) and acoustic emission techniques. Developments on the software front, including the application of concepts of Artificial Intelligence and knowledge-based systems in the form of validated expert systems for ultrasonic testing and radiography are described. The expert systems would improve interpretations to a large extent leading to reliable inspections.