Implementation of advanced ultrasonic techniques for the characterization and the measurement of wall thickness losses for the penstock diagnoses at EDF

Authors : Jérôme Delemontez
                

Company : EDF /DTG      
Country : France

Topic :

Non-Destructive Examination methods

ABSTRACT :

EDF operates approximately 600 penstocks (total length ~ 300 km). The mean operating age of these penstocks is 60 years. Therefore, in order to improve the safety level of EDF penstocks, a large diagnoses programme (SuPerHydro) has been launched. For this purpose, EDF/DTG strongly invested in new advanced ultrasonic techniques during last years in order to improve the quality and the reliability of penstock diagnoses. In this presentation, we describe the implementation of TOFD and Phased-array techniques during the in-service inspection regarding the completeness and the accuracy of measurements in comparison with standard ultrasonic technique. Some examples of the identification of metallurgical inclusions such as lamination in old steels - which generate "false calls" with standard ultrasonic techniques - are well presented. B and C-scan representation of corrosion profiles are produced and corrosion defects are easily identified and characterised.