Calculate of an additional resistance with reverse flow in steam generator under steady-state conditions

Abstract

Under a natural circulation condition, reverse flow can occur in some U-tubes of steam generator (SG), which would have a significant effect on the thermal–hydraulic characteristics of SG. A single pipe model is generally used to analyze the thermal–hydraulic characteristics of SG. However, this model will overpredict the primary circuit mass flow rates with reverse flow in U-tubes. To eliminate the limitation of this single pipe model, the new single pipe model is established by introducing an additional resistance. This paper focuses on the calculation of the additional resistance to provide some help for the simulation of SG with reverse flow in U-tubes. A mathematical model is established to calculate the additional resistance under steady-state conditions. To verify the developed models, a steady-state simulation is carried out using the RELAP code for a test facility and the calculation results are compared with the experimental data. The calculation results show an agreement with the experimental data.