2016 Volume 2 Pages 16-00056
The liquefaction and relocation of control rods at temperatures over 1200 °C due to the eutectic reaction between boron carbide and stainless steel are important phenomena for the clarification of the Fukushima Daiichi Nuclear Power Plant accident. However, the mechanism and behavior of these phenomena have not yet been understood completely. The time-resolved visualization of the dynamic and unsteady characteristics of the eutectic reaction might provide important insights into the various phenomena occurring in a time sequence. Therefore, this study employed a time-resolved visualization technique under high-temperature conditions to analyze the eutectic reaction between boron carbide and stainless steel. Among the many heating methods available, radiative heating was chosen because it facilitates clear visualization. The main problems that made this visualization difficult were the large thermal expansion, reflected light from heaters, and change in the specimen geometry due to the reaction. These problems were solved by employing novel and simple techniques. In this study, experiments were performed at different temperatures using different specimens to confirm the effectiveness of the developed technique. The maximum temperature used in the experiments was 1250 °C. Clear images were recorded. It was observed that the change in the specimen geometry affected the melt behavior. The developed technique was effective in acquiring geometrical information on dynamic phenomena at high temperatures. The technique may provide a potential data set for the validation of numerical simulations.
