A multi-scale analysis of the transient behavior of an advanced safety injection tank

A prototype full-scale facility for the advanced safety injection tank (SIT) of APR 1400, VAPER, has been simulated using the component analysis code, CUPID, and the system analysis code, MARS. In the CUPID simulations, CFD-scale calculations to simulate the local pressure drop at the control and supply nozzles of the advanced SIT are performed first. The results are used to develop flow resistance models, which are implemented into a component-scale coarse grid for the advanced SIT. Thereafter, using the component-scale coarse grid, two transient discharge experiments on the VAPER facility are simulated. Two MARS simulations are also carried out in a system scale. Using three different length-scale (CFD, component, and system scales) analyses, the transient behaviors of an advanced SIT have been successfully simulated. The results of the fine scale analysis were fed into the coarse scale analysis, leading to accurate results with less computational cost.