NDTnet 1998 Aug, Vol.3 No.8

Abstract

Over the last few years, reheat cracking has been found in a number of austenitic welds in Nuclear Electric Advanced Gas Cooled Reactor (AGR) plant. NDT has played a significant role in supporting the structural integrity arguments for continued operation of this plant. Whilst manual ultrasonic inspection has been used for the initial defect detection stage on many components, automated ultrasonic inspection has also been used both where manual access is not possible and where there is a requirement to perform monitoring of defects initially detected by manual inspection. In several cases there has been a need to respond rapidly to new automated inspection demands. One example is the development and qualification of a fully automated remote inspection of a 300mm diameter pipe weld, 7 metres from the nearest access point, in less than 2 months.

Demonstration of the capability of inspections has been an important input into the safety cases. We have achieved this through on-going generic NDT development work to underwrite the specific ultrasonic techniques being deployed coupled with inspection-specific Qualifications involving a combination of Technical Justifications and test block trials.

A key to the successful implementation of these automated inspections has been a consistent approach to equipment, procedures and personnel. This not only reduced the lead time required for new inspection applications but also enabled Technical Justifications to build on work carried out for previous applications thus reducing the time and cost associated with Inspection Qualification.

The inspection systems used for these applications are all based on the proven MIPS/GUIDE software developed by Nuclear Electric used in conjunction with a Rolls-Royce & Associates Micropulse Flaw detector. This combination has already been subject to independent validation including blind test block trials prior to use for Sizewell B PWR pre- and inservice inspections. Operators of the MIPS/GUIDE software are subject to a standard formal training and certification process which has resulted in over 100 trained operators from a complement of 9 different companies. This pool of trained resource has enabled us to respond flexibly to site demands with over 30 people being deployed during one period.

This paper gives an overview of the inspection work carried out to date using specific inspection applications to illustrate the key features of the inspection strategy which has been deployed.

Abstract Source:
Book of Abstracts, 7th European Conference on Non-Destructive Testing, 26-29 May 1998, ISBN: 87-986898-0-00

Full-Text Source:
Proceedings of the 7th European Conference on Non-Destructive Testing, 26-29 May 1998, ISBN:

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