Development and validation of multi-dimensional sodium combustion analysis code AQUA-SF

In the Liquid metal fast reactor (LMFR) using liquid sodium as a coolant, it is important to evaluate the effect of the sodium combustion on the structure, etc. Most of the previous analytical works are based on a zone model, in which the principal variables are treated as volume-average quantities. Therefore spatial distribution of gas and structure temperatures, chemical species concentration are neglected. Therefore, a multi-dimensional sodium combustion analysis code AQUA-SF (Advanced simulation using Quadratic Upstream differencing Algorithm - Sodium Eire version) has been developed for the purpose of analyzing the sodium combustion phenomenon considering the multidimensional effect. This code is based on a multi-dimensional thermal hydraulics code AQUA that employs SIMPLEST-ANL method. Sodium combustion models are coupled with AQUA; one is a liquid droplet model for spray combustion, and the other is a flame sheet model for pool combustion. A gas radiation model is added for radiation heat transfer. Some other models necessary for the sodium combustion analysis, such as a chemical species transfer, a compressibility, are also added. In AQUA-SF code, bounded QUICK method in space scheme and bounded three-point implicit method in time scheme are implemented. Verification analyses of sodium combustion tests shown in the following have been carried out: pool combustion test (RUN-D1), spray combustion test (RUN-E1), sodium leakage combustion test (Sodium Fire Test - II), small-scale leakage combustion test (RUN-F7-1). In each verification analysis, good agreements are obtained and the validity of AQUA-SF code is confirmed. (author)