Thermal hydraulic simulation of the steam generator under fast transient events

Abstract

A multidomain computational procedure was applied to model the RD-14M steam generator. It was based on the two-fluid Eulerian approach to model the water–steam flow, the blending method for interfacial force terms, the wall heat partition model (RPI) for wall boiling, and the conjugate heat transfer (CHT) method for thermal coupling between the primary and secondary circuits. The computational model of the overall steam generator is achieved by combining full 3D simulation in the riser and 0D modeling with ad hoc Dynamic Boundary Conditions (DBC) in separator/dryer, downcomer, and pre-heater regions. The implementation was carried out in the OpenFOAM(R) environment. Both steady state nominal conditions as well as transient events, such as loss of power supply and reactor shutdown, were studied. The results were compared with previous RELAP5 and full-3D models getting quite good agreement. The information obtained was very useful to understand the overall thermal-hydraulic behavior of steam generators but also local phenomena around the tubes and baffles inside the riser, which are unavailable in system-code models.