Predicting

article info
Article history: Received 10 March 2010 Received in revised form 2 July 2010 Accepted 14 July 2010
abstract
Erosion–corrosion (EC) is a serious degradation mechanism of piping, especially for nuclear power plants since it may result in the piping damage, plant shutdown, or personnel injury. The majority of this paper investigates the dependence of wall thinning on the hydrodynamic characteristics using the computational fluid dynamics (CFD) methodology. Four piping systems in a pressurized water reactor (PWR) power plant are selected in this investigation. Based on the plots showing the measured wall thinning with the calculated hydrodynamic parameters, the relationship between them is clearly revealed. Utilizing the characteristics of near-wall turbulence kinetic energy, an envelopment model is proposed herein to conservatively predict the amount of wall thinning distributed on the pipe wall. This estimation model can simply predict the possible distributions of severe EC wear sites and subsequently assist the plant staff to schedule the pipe wall monitoring program in the measured range of pipe wall for the fittings.
∗ Corresponding author. E-mail address: ymferng@.tw (Y.M. Ferng).
0029-5493/$ – see front matter © 2010 Elsevier B.V. All rights reserved. doi:10.1016/j.nucengdes.2010.07.031
The EC phenomenon had been investigated by previous simulation works or models which include CHEC code (Chexal et al., 1989), MIT model (Wu, 1989), CEACE code (FPI, 1991), EdF model (Remy and Bouchacourt, 1992), one-dimensional (1-D) flow models (Postlethwaite et al., 1986; Postlethwaite and Lotz, 1988; Blatt et al., 1989; Zeisel and Durst, 1990; Neisc and Postlethwaite, 1991a,b), and three-dimensional (3-D) two-phase computational fluid dynamics (CFD) model coupled with appropriate EC indica-
Nuclear Engineering and Design 240 (2010) 2836–2841
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Nuclear Engineering and Design
journal homepage: /locate/nucengdes
Predicting the wall thinning engendered by erosion–corrosion using CFD methodology
Yuh Ming Ferng ∗, Bin Hong Lin
Department of Engineering and System Science, Institute of Nuclear Engineering and Science, National Tsing Hua University, 101, Sec. 2. Kuang-Fu Rd., Hsingchu 30013, 325 Taiwan, ROC
C∞
concentration away from the wall surface (mol/mol)
hm
mass transfer coefficient (1/s)

k
turbulence kinetic energy (m2/s2)
p
pressure (N/m2)
R
total metal loss rate (1/s)
tors (Ferng et al., 1999a,b, 2000, 2008; Ferng, 2008), etc. Recently, a sophisticated model (Naitoh et al., 2009; Uehara et al., 2009; Uchida et al., 2009) was proposed to predict the EC occurrence and wall thinning rate, which combines a 1-D system code, a 3-D CFD code, a static electrochemical analysis and a dynamic double oxide layer analysis.
The majority of this paper is to investigate the relationship of wall thinning with the calculated hydrodynamic parameters for the piping in the NPP using the CFD methodology, which is an extended study of previous works (Ferng et al., 1999a,b, 2000). Four kinds of piping are selected in the present study and are belong to the feedwater piping system (AE-019), the main turbine piping system (AC-069) and two piping systems connecting the feedwater reheater to the reheater drain tank (AF-166 and 167), the MSR drain tank to the feedwater drain tank (AF-168 and 169), respectively. These four piping systems are located in the balance of plant (BOP) of a pressurized water reactor (PWR) that is at the southern tip of Taiwan. The local measured wall thinning on the wall surface of fittings in these piping systems are plotted versus the hydrodynamic parameters calculated by the CFD model in order to find their dependent trends. In addition, based on the curve describing these relationships, an envelopment model can be also derived to conservatively predict the amount of local wall thinning using the calculated hydrodynamic characteristics. This quick estimation model is useful to assist the plant staff in scheduling the pipe wall monitoring program.
Y.M. Ferng, B.H. Lin / Nuclear Engineering and Design 240 (2010) 2836–2841
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Nomenclature
C
concentration on the wall surface (mol/mol)
Ceq
equilibrium concentration (mol/mol)
© 2010 Elsevier B.V. All rights reserved.