Development of regulations on Flow Accelerated Corrosion

Authors : V.I. Baranenko¹, Yu. Yanchenko¹
                 M.O. Ampilogov¹, V.A. Yurmanov²
                       O.M. Gulina³

Company : ¹VNIIAES, Moscow                  
                   ² ENES/NIKIET,Moscow
                   ³ IATE, Obninsk

Country : Russia

Topic :

Wall thinning management
FAC predictions tools

ABSTRACT :

 The list of regulations on flow-accelerated corrosion (FAC) issues developed for Russian NPPs includes software for FAC rate calculation and wall thinning prediction in single-phase and two-phase fluid flows, codes and standards for pipe wall thickness, codes for pipe material chemical composition and a number of other documents.

Russian software tools and regulations are consistent with similar computer codes and codes and standards used in foreign NPPs. The process of FAC regulations introduction at Russian NPPs has been hindered by a number of causes.

         So far, industry-wide regulations for FAC rate calculations and determination of plant piping and component service lives before loss of wall thickness are not available.  Such regulations should be based on the analysis of a huge amount of accumulated inspection data for piping operating in the similar environment. The necessary data for VVER and RBMK plants is currently not sufficient.

         In 2008, regulatory document ЭО 0571-2006 on maximum acceptable pipe wall thickness was removed from the list of the existing plant documentation due to the lack of regulations for FAC prediction, because prognosticated wall thickness at the end of the interval between inspections should to be compared to standards specified in the said regulations.

          The report highlights peculiarities of the existing FAC-related computer codes and regulations and the need for developing unavailable regulatory documentation. The report dwells on the organization of in-service FAC inspection at plants under the conditions when the necessary regulatory documentation is unavailable.