Abstract
Information concerning the spatial distribution of debri in the containment vessels is of considerable importance in the decommission process of Fukushima Dai-ichi nuclear power plants. Since the cross-sectional area of the debri jet discharged from a reactor vessel may have great impact on the spatial distribution of debri, experiments of liquid jet were carried out in the present work Particular attention was paid to the effects of the nozzle shape and the back pressure In addition, spreading characteristics of debri on the pedestal floor was investigated through numerical simulation using the SAMPSON code.
