Quasi-Eulerian method for analyzing slug impact and coolant spillage in a fast-reactor accident

This report describes a quasi-Eulerian method which has been incorporated into the ICECO code to study slug impact and coolant spillage problems in a fast-reactor accident. The quasi-Eulerian cells used in this method are located on the tops of the regular cells. The axial size of the quasi-Eulerian cells varies according to the gap generated at the reactor head-wall junction. Penetration holes on the cover head are modeled on the top center of the quasi-Eulerian cells. Fluid variables in these quasi-Eulerian cells also satisfy all the conservation equations. Since the boundary pressures above the quasi-Eulerian cells are determined by the movement of the moving grid, the velocity of the cover head is also included in the pressure iteration. Several examples are given to compare the results obtained by this quasi-Eulerian method with the existing experimental excursion data, as well as with the analytical and the other code solutions