Hydrodynamic simulations are performed to study Richtmyer-Meshkov instability (RMI) and material ejection at a metal-vacuum interface using a 2D multi-component elastic-plastic hydrodynamic Eulerian code. Effect of material strength on instability development of roughened surface is analyzed, and relationship between amount of ejected material and saturated bubble amplitude is revealed. Finally, based on RMI theory for elastic-plastic solids, theoretical models to describe critical condition of ejecta formation, total amount and maximum velocity of ejecta from unmelted metals are established.

For flow instabilities in inverted U-tubes steam generator (SG),a dimensionless analysis is made for flow equation.Criteria of flow stabilities (characteristic Reynolds number) are derived according to small perturbation analysis.With calculation for a certain type of SG,effect of inlet fluid temperature and U-tube bend radius on the criteria are studied.It shows that the characteristic Reynolds number increases with the increase of inlet fluid temperature.Relations between U-tube bend radius under different inlet temperatures are complex.It is useful for calculation of flows as well as space distribution of reverse flow in a SG.