Mitigation measures against severe accidents (SAs) are important from the viewpoint of safety of nuclear reactors. In some scenarios of the SAs, the core materials melt and fall into a water pool in the lower plenum as a jet. The molten material jet is broken up, and heat transfer between molten material and coolant is occurred. This process is called a fuel-coolant interaction (FCI).
The aim of the present study is to clarify the liquid jet behavior falling into a shallow pool. Our focus is on the atomization conditions of a liquid jet injected into the pool with insufficient depth.
In order to understand the jet behavior in a shallow pool, we performed observation of visualization with several methods and mapped observed flow regimes of jet against dimensionless numbers. As a results of observation, we succeeded visualization of internal flow.