TITLE:
CFD-Based Optimization of UT Inspection Grid Spacing for Detecting Cavitation Erosion in Piping Components
AUTHORS:
Kyeongmo Hwang, Bongjin Ko, Jonghyeon Kim, Junhyeon Park
KEYWORDS:
Cavitation, UT Inspection, UT Grid Spacing, CFD Analysis, Absolute Pressure, Dynamic Pressure
JOURNAL NAME:
World Journal of Nuclear Science and Technology,
Vol.16 No.4,
October
31,
2026
ABSTRACT: Representative aging mechanisms responsible for erosion in piping systems installed in nuclear power plants include cavitation, flashing, liquid droplet impingement erosion, and solid particle erosion. Unlike general corrosion and flow-accelerated corrosion (FAC), which typically affect relatively large areas, these erosion mechanisms can cause highly localized damage. Because erosion results in localized wall thinning, the ultrasonic testing (UT), which is widely used for pipe wall thickness inspection, may have limitations in accurately identifying localized damage. Accordingly, this study investigated the flow variables associated with erosion-prone regions using computational fluid dynamics (CFD) and determined an appropriate UT inspection grid spacing based on the axial distance over which these variables influence the inner pipe wall. The commercial CFD code ANSYS FLUENT was employed for all simulations. Cavitation analyses were performed for four pipe sizes equipped with an orifice plate by varying the inlet pressure under five or six operating conditions for each pipe size. To determine an appropriate inspection grid spacing for detecting erosion damage, the UT grid spacings specified in EPRI NSAC-202L were used as a reference for comparison.