Numerical Validation of AQUA-SF in SNL T3 Sodium Spray Fire Experiment

Abstract

In order to investigate the effect of sodium combustion, Sandia National Laboratories (SNL) and Japan Atomic Energy Agency (JAEA) have exchanged information of sodium combustion modeling and related experimental data in the framework of Civil Nuclear Energy Research and Development Working Group (CNWG). This collaboration includes a benchmark analysis of the SNL Surtsey spray combustion experiment (SNL T3 experiments) using AQUA-SF and SPHINCS in JAEA. In this paper, investigation into multi-dimensional effect and best estimate for T3 experiment with AQUA-SF are conducted as validation and verification of the code. A spray combustion is characterized by formation of sodium droplet cloud due to pressure difference and their spreading with combustion. Therefore, the combustion phenomenon will be much affected by spatial distributions of parameters such as gas temperature, gas velocity and oxygen concentration. As a best estimate analysis, the spray burning duration is adjusted in the computation in order to take into account the temporary suppression of the spray combustion observed in the experiment. Furthermore, droplet size of SPHINCS and AQUA-SF are optimized to represent the T3 experimental results. For the best estimate in AQUA-SF, sodium droplet size needs to be set larger than SPHINCS in order to decrease the surface area and suppress the spray burning rate. These adjustment leads to more precise representation of the measurements in T3 experiment.