Ryo Yokoyama (D1), Department of Nuclear Engineering and Management , won “The Frontier Spirit Award (Best Presentation Award)” at NDEC-6



〈Name of award and short explanation about the award〉
”The Frontier Spirit Award (Best Presentation Award)”
It was given for the best presentation at 6th Conference for R&D Initiative on Nuclear Decommissioning Technology by the Next Generation : NDEC( NDEC-6).

About awarded research〉
Title:Investigation of the outflow and the solidification behavior of stratified molten metal

During the Fukushima Daiichi Nuclear Power Plants accident, it is likely that the molten corium stratified between the fuel and the structural components in the RPV due to the difference of their density and their melting points. Eventually, it spread on the PCV bottom. In that case, there is a possibility that the entire fuel debris is divided into 2 regions where the fuel is rich and the structure is rich. This outcome should be taken into consideration when the retrieval of the fuel debris begins. The authors investigated the outflow behavior of the stratified molten metal and the subsequent material distribution in the solidified metal using both the experiment and the numerical simulation. The results indicated that the material distribution in the solidified material was largely affected by the outlet diameters. The authors revealed that understating the RPV degradation condition is an important issue to predict the fuel debris distribution in the Fukushima Daiichi Nuclear Power Plants.

〈Your impression & future plan〉
I am honored to receive a prestigious award at this time. I would like to appreciate my supervisors Prof. Shunichi Suzuki, Prof. Koji Okamoto, and my cooperative researchers. I am going to be focusing on the research to contribute to decommissioning of the Fukushima Daiichi NPPs.