Application of Three-Dimensional Thermal-Hydraulic Code BAGIRA for Modeling Complex Two-Phase Flows in Primary and Secondary Circuits of NPP's with VVER-1000

摘要

the main features of the three-dimensional thermal-hydraulic BAGIRA code physical models are presented along with some applications to modeling two-phase flows in NPP circuits. In particular, a simulator model for primary and secondary circuits of an NPP with VVER-1000 is considered, using three- and two-dimensional nodalizations for the vessels of reactor and steam generator (SG), respectively. Then, a fully three-dimensional research model of the VVER-1000 horizontal SG is exposed, which incorporates all important SG elements. The essentially non-uniform heat release profile both along and across the SG vessel, together with specific SG design features, stipulate for a complex and non-trivial flow pattern. Some thermal-hydraulic flow parameters for stationary conditions - volumetric mixture velocities and void fractions - are calculated and compared with the experimental data.