Liquid Droplet Impingement Erosion Research Articles

0601 液滴衝撃エロージョン予測のための蒸気実験による液滴径計測(S45-1 原子炉システムおよびその要素技術(1),S45 原子炉システムおよびその要素技術)

Liquid droplet impingement erosion (LDI) is defined as an erosion phenomenon caused by high-speed droplet attack in a steam flow. In a power plant, pipe wall thinning by LDI is observed steam piping system. Because LDI usually occur very locally and is difficult to detect, a prediction of LDI location is required for the safety of the plant system. Because LDI is almost dominated by fluid factor like droplet velocity and diameter, there is a possibility to predict the location of wall thinning by LDI if local flow condition is clarified. Though the local flow condition can be obtained by calculation, droplet diameter is difficult to calculate So, in this study, we conducted steam experiment to measure the droplet diameter by PDPA, and tried to clarify the characteristics of the droplet and the correlation between droplet diameter and state quantities of the flow. We found that a distribution of the droplet diameter could be approximated by gamma distribution that is a general form of an exponential distribution. For the correlation between the diameter and the state quantities, we considered the change of the heat energy in addition to a surface tention and a shear force, and checked the correlation between the quantity and droplet diameter. As a result, we observed good correlation between them and suggested approximate equation.

ICONE15-10722 JSME Activities to Establish a Standard for Pipe Wall Thinning Management of Power Plants in Japan

The Japan Society of Mechanical Engineers (JSME) organized a special task group for dealing with pipe wall thinning issues under the Main Committee on Power Generation Facility Codes (MC-PGFC) to prevent pipe rupture due to pipe wall thinning, which was requested by the industry as well as the regulatory side. First, JSME established a performance-based rule entitled "Code for Power Generation Facilities -Rule on Pipe Wall Thinning Management- JSME-S CA1 2005," in which the basic requirement for managing pipe wall thinning is described. In this rule, technical knowledge regarding pipe wall thinning phenomena including flow accelerated corrosion (FAC), liquid droplet impingement erosion, and cavitation erosion was also described as an attachment. Second, JSME established technical rules for thermal power plants, PWRs, and BWRs, respectively, which fully complied with the performance-based rule. In this report, the background on the establishment of pipe wall thinning rules, the organization of the code committee, the content of the rules, and the technical knowledge that specialists among JSME members investigated are outlined.