Ongoing Validation of Sodium Fire Analysis Code System for SFR Safety Evaluation

摘要

Evaluation of thermal consequence in a plant building is one of the important issues in the safety evaluation of sodium-cooled fast reactor (SFR) plant when we take into account the accidental situation of liquid sodium leak and fire. Therefore our institute Japan Atomic Energy Agency has developed a sodium fire analysis code system which can predict the important accident consequences of gas pressure increase and structure temperature increase during sodium fire. The system has various computational programs including the ASSCOPS code for sodium spray and pool fire analysis in two-cell geometry, the SPHINCS code for simultaneous spray and pool fire analysis in multi-cell geometry, the AQUA-SF code for three-dimensional analysis of an atmospheric gas region, and the other computational modules for individual phenomenon such as equilibrium chemical reaction, sodium aerosols behavior, etc. This paper describes outline of the sodium fire code system and current status of ongoing activity on verification and validation of the system for demonstrating reliability and accuracy of the codes. As a practical example, the present paper includes the explanation of spray fire model validation with single sodium droplet combustion tests. Furthermore, it is demonstrated from a numerical experiment that the three-dimensional gas thermal-hydraulic analysis would predict local effect in a spray fire region leading to more realistic and precise estimation of accident consequence.