Inspection qualification and NDE reliability
C Curtis, A Walker and I Atkinson
Wood Inspection Validation Centre (IVC), Lovell House, Birchwood, Warrington, UK
Email: chris.curtis@woodplc.com / anthony.walker3@woodplc.com / ian.atkinson2@woodplc.com
Inspection qualification is a regulatory requirement within the UK for the NDT of the most safety-significant welds and locations on nuclear power plants. In general, inspection qualification is undertaken in accordance with the ENIQ methodology for the qualification of NDT and similar requirements extend to a number of European, and other, countries.
While an NDT system is qualified in accordance with ENIQ it is often considered to be both highly reliable and highly capable, it is very difficult to be certain what is meant by such terms, their relationship to probability of detection (POD) and how they are verified during inspection qualification. This paper discusses some of the philosophical and practical difficulties in assigning ‘highly reliable and capable’ to a qualified inspection system. In particular, whether such labels imply a single value of reliability and capability (single valued probability of detection) for all qualified NDT systems or not and also whether there can be a practical limit put on qualification effort to achieve a particular level of NDT reliability and capability.
While an NDT system is qualified in accordance with ENIQ it is often considered to be both highly reliable and highly capable, it is very difficult to be certain what is meant by such terms, their relationship to probability of detection (POD) and how they are verified during inspection qualification. This paper discusses some of the philosophical and practical difficulties in assigning ‘highly reliable and capable’ to a qualified inspection system. In particular, whether such labels imply a single value of reliability and capability (single valued probability of detection) for all qualified NDT systems or not and also whether there can be a practical limit put on qualification effort to achieve a particular level of NDT reliability and capability.
