Izvestiya vuzov. Yadernaya Energetika

The peer-reviewed scientific and technology journal. ISSN: 0204-3327

Substantiation of fac rate and service life estimation under operation control data

3/28/2016 2016 - #02 Modelling processes at nuclear facilities

Baranenko V.I. Gulina O.M. Salnikov N.L. Murzina O.E.

DOI: https://doi.org/10.26583/npe.2016.2.06

UDC: 621.311.25:621.039.620.193.1

The paper deals with development of procedure of FAC rate estimation. Flow accelerated corrosion – complex mechanism of NPP equipment elements damage. Its rate depends on such factors as metal corrosion, stream hydrodynamic, equipment elements geometry (straight parts of piping, welding area, bending and etc.), operating conditions, operation time, metal composition, thickness of corrosion product deposits and others. Decrease of element wall thickness is due to metal corrosion, increase ofelement wall thickness is due to corrosion product deposits. Arising of accuracy of service life prediction it is necessary to reduce uncertainties connected with control means and data quality. At present trust in procedure of FAC rate estimation is absent. Estimation of residual service life for NPP equipment elements also needs in above-mentioned procedure.

Development of FAC rate estimation procedure is based on analysis of control data. There are calculating main indexes of FAC such as numbers of both increasing wall thickness and decreasing one, rate of wall thickness decreasing and rate of corrosion product deposing.

Wall thickness decreasing due to FAC is accompanied by corrosion product deposing on the inner surface of piping. Due to this process the calculated residual service life formally is increasing. However, real wall thickness under corrosion product deposit is unknown as well as initial wall thickness.

To correspond to the facts, the new procedure of FAC rate estimation must be well-grounded. Research performed leads to original procedure taking into account tolerance of manufacturing on piping wall thickness and corrosion product deposit influence on both initial and minimal measured wall thickness (in all, three coefficients). To estimate the residual service life new index – safe coefficient - is using. This coefficient is recommended by international practice of NPP operation. Additional coefficients allow increasing of FAC rate calculation conservatism about 2,5 times in comparison with FAC rate calculation based on nominal wall thickness.


  1. RD EO «Normy dopuskaemyh tolschin stenok elementov truboprovodov iz uglerodistyh stalej pri erozionno-korrosionnom iznose» [Norms of admissible wall thickness for carbon steel piping under flow accelerated corrosion]. Мoscow. VNIIAES Publ. 2012, 104 p. (in Russian).
  2. Sweden country presentation IAEA FAC RCM 2. On the risk of using grid measurements when close to allowable minimum wall thickness. Erlangen, 2014.06.05.
  3. Ruszhak M., Shplichal K., Kaplan J. The complex approach to the flow accelerated corrosion in Czech nuclear power plants. Proceed. of specialists meeting organized by the Inter. Atomic Energy Agency. 19-22 Sept, 1994, IAEA Vienna held in Kiev, Ukraina. 1994, pp. 215-228.
  4. Ruszhаk M., Kaplan J., Kadechka P. Complex Approach to the Lifetime Evaluation of WWER secondary Piping due to Erosion-Corrosion. Proceed. of the IAEA Specialists Meeting on Erosion/Corrosion of Nuclear Power Plant Components. – Russian Federation, Vladimir. Sept. 13-16 1996, pp. 24-30.
  5. Ruszhak M. Reshenie problematiki erozionnoy korrozii truboprovodov vtorogo kontura atomnyh elektrostanciy [Piping Erosion-Corrosion at the second outline of NPP] Institut yadernyh issledovanij. Cheshskaya respublika, Rzshezh. 1995, 16 p.
  6. Recommendation for an Effective Flow-Accelerated Corrosion Program (NSAC-202L-R1). 1301-01. Nov. 1996. 59 p.
  7. Recommendations for an Effective Flow-Accelerated Corrosion Program, EPRI, Palo Alto, CA: 1999. NSAC-202L-R2.
  8. Recommendation for an Effective Flow-Accelerated Corrosion Program (NSAC-202L-R3). 1011838. May 2006. 92 p.
  9. Recommendation for an Effective Flow-Accelerated Corrosion Program (NSAC-202L-R4) / 3002000563. Technical Report, Nov. 2013. 94 p.
  10. Case of ASME. Boiler and Pressure Vessel Code. CASE N-480. May 10, 1990, pp. 787-795.
  11. Case of ASME. Requirments for Analiyical Evaluation of Pipe Wall Thinning. Section XI, Devision 1. CASEN-597-2. November 10, 2003. 13 p.

flow-accelerated corrosion corrosion products deposit wall thickness control data procedure of flow-accelerated corrosion rate estimation residual service life minimal admissible wall thickness