ANPP Piping Wall Thickness Measurement by Ultrasonic Method

Author : Gurgen Mailyan

Company : Armenian NPP
    
Country : Armenia

Topic :

Flow Accelerated Corrosion

Non-Destructive Examination methods

Wall thinning management

Operation feedback

ABSTRACT :

It is well known, that in the secondary circuit piping of  NPP (e.g. VVER type) made of  carbon steels at their operation, events with breaks and leaks from some components caused by their corrosion (erosion) were observed. Under this sense in the Metal laboratory of ANPP during in service inspections the investigations of piping metal condition were carried out by nondestructive methods, and particularly, UT  thickness measurements on the potentially dangerous components.

During 2004 - 2009years Thickness measurements of some components (elbows, reducers, tees) of ANPP secondary piping selected lines were performed by Czech and Armenian experts conjointly, within the framework of IAEA ARM/9/016 project  (FAC assessment of secondary circuit of ANPP Medzamor). The results have been analyzed and systematized in NRI (Rež, Czech Rep.) reports.

After publication the Russian document РД ЭО 0571-2006  -"The allowed thickness norms of the NPP carbon steel piping components ", since 2007  the thickness measurements and analysis  results were curried out by using of this document's principles. Upon completion of the Project Program, since 2009, the works are carried out by ANPP  in the Metal laboratory on its own (independently). During inspections the components strongly thinned sites typical for FAC were detected. Such components have been replaced or repaired. In this report an example of such a detection is demonstrated.