2017 | AFC ACCOMPLISHMENTS 116 Figure 1. Still-frame progression from high-speed video of high energy RIA experiments performed in TREAT in the mid-1960s (https://youtu.be/h0o4P_F4s9s). Fuel-coolant interaction (FCI) has long been a subject of interest in severe-accident reactor safety applications. Early transient testing in Idaho focused heavily on providing insight to the phenomenological behavior and consequences of such events. Since then, several out-of-pile experiments have studied these interactions, though effective analytical treat- ment has never been accomplished thus requiring significant margins from the thresholds of such events. In high energy events in water, significant cladding-coolant chemical interaction and resulting thermal energy may play a role in further propagation of the energetic event. High energy FCI events (molten In-Pile Fuel-Coolant Interaction (FCI) Studies Supporting Transient Testing Experiments Principal Investigators: Colby Jensen Collaborators: Nicolas Woolstenhulme (INL), Daniel Wachs (INL), Michael Corradini (UW-Madison)