Evaluation of the Flow Accelerated Corrosion downstream of an orifice (Measurement of Corrosion Rate)

Authors : Yukinori Nagaya¹, Akira Nakamura²,
                 Michio Murase¹, Yoichi Utanohara²

Company : ¹Institute of Nuclear Safety System, Inc.

                    Department of Nuclear Power and Energy
                    Safety Engineering, University of Fukui
                   ² Institute of Nuclear Safety System, Inc.

Country : Japan

Topic :

Flow Accelerated Corrosion

ABSTRACT :

Flow accelerated corrosion (FAC) is one of important issues for aging of power plants. In order to evaluate the effects of flow field on corrosion rate due to FAC, we were conducted numerical analyses of flow field and measurements of flow field and corrosion rate. In this report, we described the results of corrosion rate measurements in the downstream from an orifice by electric resistance method(ERM). In the measurements, we used high-temperature water loop with the inner diameter L of 50mm, then the measurement conditions were set at the water temperature of 423 K and the average velocity of 5.0m/s. The corrosion sensor elements were plates made of carbon steel, and they were exposed to the inner surface of pipe. By measuring its electric resistance, the corrosion rate was calculated. These sensors were mounted at 1L,2L,3L,4L,5L downstream and 3L upstream of an orifice. The maximum corrosion rate was observed from 1L to 2L after an orifice. This location agreed with the location of the maximum wall shear stress calculated by standard k-e models.