Sodium-cooled fast reactors (SCFRs) are envisioned to be the future of nuclear power generation owing to their superior response to core disruptive accidents, i.e., non-energetically and passively shutting the reactor down. Even with SCFRs, a substantial amount of fuel may melt in the core region during a disruptive accident and enter the coolant liquid pool as melt-jets. Although there have been many studies investigating the jet-coolant interaction, most were focused on the final jet fragmentation structures, quenching characteristics of the melt, or fluid dynamics of a melt-jet in a coolant pool for very low density ratios (≤ 2). However, in real-world scenarios, this density ratio of the core melt and the coolant can be much higher (≥ 10). Thus, the present study focuses on addressing this gap in the literature by performing 2D isothermal computational fluid dynamics simulations for a higher density ratio case (≈ 10) to unravel the jet break-up behavior as they present in a real-world scenario. A primary jet diameter of 7mm and a secondary jet diameter of 14mm together with a range of velocities (0.014−0.12 m/s) are pursued to establish the effect of relevant non-dimensional numbers on jet break-up characteristics and fluid dynamics of the high-density jet within the coolant in laminar regime. Two new sub-regimes, that have not been reported in the literature thus far, are observed and the flow physics behind the observed droplet dynamics is explained by carefully analyzing the corresponding vorticity contours.