Following Fukushima Daiichi, nuclear safety is paramount in advanced pressurized water reactors. In-Vessel Retention (IVR), notably External Reactor Vessel Cooling (ERVC), offers simplicity and cost-effectiveness. However, uncertainties in the corium thermal load and IVR processes mandate conservative design and safety margins. This study simulates the SAMPO experiment with nitrate salts and thermal oil to investigate the thermal hydraulics of a stratified melt pool. Analysis of power levels, heat transfer coefficients, and radiation heat transfer reveals key insights. Increasing input power raises the temperature and sidewall heat flux in the upper layer, leading to interlayer crust dissolution and enhanced upward heat transfer near the lower layer's melting point. Higher convection coefficients double the heat flux at the metal layer's top while reducing sidewall heat flux. Adjusting radiation emissivity of the front and back plates to 0.7 synchronously decreases heat flux from both the top and curved sidewalls, achieving an effect similar to a 50% power reduction without radiation.