Modelling of a CO2-gas jet into liquid-sodium following a heat exchanger leakage scenario in Sodium Fast Reactors

► Underexpanded gas-into-water jets have been investigated in the context of accidental scenario in sodium fast reactors. ► A two-fluid numerical approach with flow regime transition has been developed. ► Pressurized gas has been injected into water and optical probe technique has been employed for axial and radial void fraction measurements inside the jet. ► Numerical results agree with the experimental ones in terms of void fraction profiles.