Improvement of the MSG code for the MONJU Evaporators; Additional function of reverse flow calculation on water/steam model and animation for post processing

Toda, Shinichi; Yoshikawa, Shinji ; Watanabe, Osamu*; Kishida, Masako*; Oketani, Kazuhiro*

The improved version of the MSG code(Multi-dimensional Thermal-hydroulic Analysis Code for Steam Generators) has been released. It has been carried out to improve based on the original version in order to calculate reverse flow on water/steam side, and to animate the post-processing data. To calculate reverse flow locally, modification to set pressure at each divided node point of water/steam region in the helical-coil heat tansfer tubes has been carried out. And the matrix solver has been also improved to treat a problem within practical calculation time against increasing the pressure points. In this case pressure and enthalpy have to be calculated simultaneously, however, it was found out that using the bloci-Jacobean method make a diagonal-dominant matrix, and solve the matriz efficiently with a relaxation method. As the result of calculations of a steady-state condition and a transient of SG blow down with manual tip operation, the improvement on calculation function of the MSG code was confirmed. And an animation function of temperature contour in the sodium shell side as a post procssing has been added. Since the animation is very effective to understand themal-hydraulic behavior on the sodium shell side of the SG, especially in case of transient condition, the analysis and evalution of the calculation results will be enabled to be more quickly and effectively.