A Study on Wall Thinning Causes Identified through Experiment, Numerical Analysis and Ultrasonic Test of Main Feedwater Isolation Valve

To review the relations between flow behavior and wall thinning caused by flow-accelerated corrosion, an experiment, a numerical analysis and ultrasonic tests for the lower body of the main feedwater isolation valve were performed. The experimental results in terms of static pressure obtained for the downscaled facility were compared with those of three-dimensional (3D) numerical analysis using the FLUENT code. Based on the 3D analytical results that agreed well with the experimental results, the numerical analysis after magnifying the experimental verification model with the actual size was reperformed, and the turbulence parameters were compared with the measured wall thickness. The vertical flow in the direction of the wall was analogous to the wall-thinning configuration, and the turbulence intensity of the limited surface of the lower wall had an effect on wall thinning. These results well match those of the previous studies, where locations colliding vertically against components undergo severe wall thinning.