A five-year research project started in FY2005 to develop a code based on the Moving Particle Semi-implicit (MPS) method for detailed analysis of core disruptive accidents (CDAs) in sodium-cooled fast reactors (SFRs). The code is named COMPASS (Computer Code with Moving Particle Semi-implicit for Reactor Safety Analysis). Separated phenomena in CDAs are focused on. Both mixed-oxide (MOX) and metal fuels are considered. Eutectic reactions between the metal fuel and the cladding material are investigated by phase diagram calculation, classical and first-principles molecular dynamics. Basic studies concerning the numerical methods are performed to support the code development of COMPASS. In the validation process of COMPASS, calculations using SIMMER-III are carried out to give boundary conditions and to provide reference results. In this paper, the overall status of the project in FY2007 is provided. Two basic studies for the particle method are also described. One is the development of a unified algorithm for compressible and incompressible flow. The developed algorithm is tested by a benchmark problem of a shock tube. The result agrees well with the analytical solution. The other is the development of a turbulence model for the particle method. Large Eddy Simulation (LES) is selected. We developed a wall boundary condition to reproduce the log law near the wall with a coarse spatial resolution. Flow over a backward facing step is calculated by the present model. The result agrees with an experimental data.

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