Spent fuel pool boil-off experiments with high power and high time resolution

• Experiments conducted for high rod power boil-off conditions. • Correlation between collapsed and mixture level position deduced from experiments. • Radial and axial temperature profiles in rod bundle during boil-off investigated. • Water eruption sources and effects analyzed. • Peak temperature of 800 °C reached in ultimate boil-off scenarios. The occurrence of spent fuel pool (SFP) accidents, in which the water level decreases below the top of the fuel assemblies (FA), may arise due to the loss of active pool cooling or pool leakage. In such scenarios, the ALADIN test facility of the TUD Dresden University of Technology is utilized to simulate a comprehensive boiling water reactor (BWR) FA in a 1:1 scale. This report supplements the existing data base with rod powers between 100 W and 350 W. Boil-off experiments will be analyzed in detail in relation to axial and radial temperature profiles as a function of time and heater power up to a maximum temperature of approximately 800 °C. Additionally, temperature excursion mitigating measures such as spray-cooling and flooding will be discussed.