Nuclear Technology / Volume 162 / Number 3 / June 2008 / Pages 308-322
Technical Paper / Thermal Hydraulics
In this paper, possible influences of power uprate on the distribution characteristics of erosion-corrosion (E/C) wear sites were analyzed through proper two-phase models. These models include three-dimensional two-phase computational fluid dynamics (CFD) simulations and appropriate E/C analysis. An analytical approach was applied to boiling water reactors. Based on the simulation results, the present CFD simulations successfully predicted two-phase phenomena that occurred in the piping system including centrifugal effects, gravitational effects, an imbalance of phase and mass separation in a T-junction, etc. When coupled with the calculated two-phase flow structures, the appropriate E/C models can be used to indicate the local distributions of severe E/C wear sites on the wall of the fittings. This shows a reasonable agreement with the plant-measured results. With these models, the impacts of power uprate on the distribution characteristics of E/C wear sites can be investigated. Comparisons between the calculated results for 100, 105, and 110% power levels clearly reveal that the power uprate has an insignificant effect on the distribution characteristics of wear sites for the selected piping system under investigation, especially in the wear ranges.