Steam Generators

I

STEAM generator inspection: A KEY COMPONENT OF VVER NPP SAFETY AND AVAILABILITY 

Intercontrôle, Rungis, France

Technology transfer is and has always been a complex task for both parties in the partnership, especially in the field of nuclear energy.

This paper is intended to illustrate and to summarize the methodology applied, the results obtained and the experience gained by Intercontrôle as a member of a consortium in two projects of technical assistance.

The wide objective of both projects was to train in the methodology, the organization and the execution of NDT activities related to In-Service Inspection - one with Russia, the other with Ukraine. The paper focuses on the specific activities concerning steam generator eddy current inspection (ET) with the emphasis on the work already performed at Rovno NPP in Ukraine.

Since VVER steam generator replacement on regular basis is no longer considered as the best solution of the problems met on this structure, the importance of In-Service Inspection in order to detect, localize and characterize the defects on the tubes and/or in the collector has become extremely important.

The paper shows the different phases of the project from equipment delivery, training of personnel regarding inspection organization and preparation, inspection performance - data acquisition, analysis and management, up to final report issuing and its presentation to the authorities.

Several examples of ET signals obtained on site are given in order to illustrate the techniques applied and the types of defects found on both 440 and 1000 MWe VVER steam generator tubes.

The personnel of the power plants involved in the project in both acquisition and analysis has already reached a good level to continue to perform future work concerning ET inspection of steam generators. Of course, technical assistance - especially for data analysis - is still necessary, the final goal to reach being to make the personnel completely autonomous as regards SG eddy current testing.