Investigation on droplet impingement erosion during steam generator tube failure accident

Droplet impingement erosion is one of the reasons causing the secondary heat transfer tube damage in case of the heat transfer tube failure in the steam generator of sodium-cooled fast reactor. This paper has been dedicated to investigate the impingement phenomena, pressure load and the damage rate by impingement. Single droplet impingement on the rigid wall was first simulated with MPS-AS (moving particle semi-implicit method for all speeds) method for water and sodium. The shockwave propagation during the impingement has been well captured. The pressure load by water impingement can be characterized with Heymann's correlation (1968). A correlation for pressure load by sodium impingement is proposed based on the water hammer theory. The new correlation shows to be consistent with the simulation result. For prediction of erosion rate by sodium droplet impingement, Heymann's empirical correlations (1979) were extended by including the effects of liquid properties, i.e. density, sound speed and viscosity. The extended correlations show similar prediction accuracy to the original ones.

► Sodium droplet impingement is regarded as one of the mechanisms causing secondary tube failure in case of steam generator tube rupture accident.
► The moving particle semi-implicit (MPS) method is applied to simulate the sodium droplet impingement.
► The erosion rate correlation for water impingement is extended for application in the sodium impingement.