Evaluation of flow accelerated corrosion of PWR secondary components by corrosion analysis coupled with flow dynamics analysis

In order to predict and mitigate flow accelerated corrosion (FAC) of carbon steel piping in PWR secondary systems, computer packages for evaluating FAC have been developed by coupling three dimensional (3D) computational flow dynamics (CFD) and corrosion models. (1) Evaluation of FAC occurrence [Computer package (1)]. Mass transfer coefficient at pipe surface is calculated with 3D flow dynamics models, while local oxidant distribution along the flow path is obtained by N2H4-O2 reaction calculation. FAC occurrence can be predicted by combining turbulence effects at the surface with corrosion conditions. (2) Quantitative evaluation of wall thinning [Computer package (2)]. Wall thinning due to FAC can be evaluated with the modified double oxide layer model at the location pointed out by the computer package (1). (3) Evaluation of the effects of countermeasures to mitigate FAC. The effects of candidates for countermeasures on FAC mitigation can be evaluated by applying the computer packages (1) and (2). (author)