A scoping study of debris bed formation in the DEFOR test facility

Motivated to understand the processes which govern the formation and characteristics of a debris bed and hence its coolability during a postulated severe accident of a light water reactor, a new research program called DEFOR (DEbris FORmation) was initiated at the Royal Institute of Technology (KTH). This paper presents results obtained in scoping experiments conducted during an initial phase of the DEFOR program. The DEFOR-E test campaign is concerned with the DEFOR test facility commissioning and exploratory study of phenomena occurred during a debris bed formation. Binary oxide mixtures at different superheat temperatures were used as the corium melt simulants. The scoping experiments revealed the effect of water pool depth and subcooling, melt mass and material properties on the debris bed characteristics. Insights gained from the DEFOR-E test campaign help guide the scaling, design and operation of the subsequent experiments in the DEFOR program.