Fuel Coolant Interaction of Liquid Tin.

In the case of a severe accident in a nuclear power plant the reactormay heat up, melt and mix with fuel material to form a substance calledcorium. In today's nuclear power plants the primary strategy to cool thecorium in the event of a severe accident is to flood the ex-vessel cavitywith water. The reactions which occur when the liquid metal comes incontact with the water, known as fuel coolant interaction (FCI), can beviolent and in the worst case scenario lead to containment failure. Inthe MISTEE laboratory at KTH, small scale FCI experiments are conducted.This thesis explores how dierent temperatures of liquid tin andwater aects the presence of steam explosion. Higher melt superheat andlower water temperature was found to increase the likelihood of steamexplosions. Furthermore, a phenomenon was observed, hereby referredto as immediate steam explosion, where the melt exploded immediatelyupon contact with water. All previous research found states that steamexplosion only occurs in the later stages of FCI, thus the results are contradictory.The thesis also includes research on jet breakup in the initial phaseof FCI and how it is affected by melt velocity, diameter and temperatureas well aswater temperature. The experiments performed did not yielddata which could be analyzed so no conclusions could be drawn.