Modeling and Evaluation of Effective Parameteres of FAC

Topics :

Flow Accelerated Corrosion
Steam-water circuit chemistry

ABSTRACT :

Modeling of hydraulic and water-chemistry parameters affecting on FAC have been conducted in this study. Mass transfer coefficient, as hydraulics, was modeled by introducing "effective friction velocity" which includes the effect of mean and turbulent velocity at near-wall region of eccentric flow. The effective friction velocity replaces the original friction velocity for fully-developed turbulent flow in a straight pipe, to evaluate FAC susceptible area. This mass transfer model was confirmed to show qualitative trend with FAC experimental data obtained in CRIEPI. As for water-chemistry, effects of temperature, pH, dissolved oxygen concentration, and chromium content were modeled in parallel by assuming the existence of saturated layer on oxide surface in constant FAC rate condition. Fluxes of iron, chromium, oxygen and hydrogen through the diffusion layer, which lies between the saturated layer and the bulk water, were modeled by considering their balance of production and consumption. The trends of FAC rate for each parameter were compared with previous studies and good agreements were confirmed, qualitatively.

Speaker Biographical Information

After joining CRIEPI in 1996, engaged on research of thermal-hydraulics related to large-bore two-phase flow and scale adhesion in PWR secondary line. From 2004, started the study of FAC from hydraulic point of view, and conducting experimental and theoretical approach for modeling. Attended FAC 2008 as a speaker.