Abstract
This paper presents the work carried out in Experimental and design organization OKB “GIDROPRESS” to justify the separation characteristics of VVER-TOI steam generator (SG) using the STAR-CCM+ CFD-code. In the VVER-TOI project, new layout solutions were applied in the reactor plant as part of which the steam removal system from the SG was changed. Namely, in contrast to the VVER-1000 and VVER-1200 where the steam removal was organized through ten nozzles combined into a steam collector, in the VVER-TOI SG the steam removal was arranged through one nozzle located on the cold collector side. This change leads to the formation of a nonuniform velocity field in the separation volume, between the evaporation surface and the distribution perforated plate (DPP), and can lead to the excessive increase of steam humidity. To ensure the steam separation characteristics of a horizontal SG with one steam nozzle, it was proposed to create a nonuniform resistance on the way of steam motion from the evaporation surface into steam nozzle applying a nonuniform degree of the DPP perforation. Two computer models of the SG steam volume with different steam removal schemes (through one and ten nozzles) were developed, a set of studies on verification and validation was carried out and a set of calculations were performed. According to the results of the calculations, the necessity of introducing a nonuniform degree of the DPP perforation was justified. Further, to determine the nonuniform degree of DPP perforation, a set of optimization calculations of the SG steam volume with one steam removal nozzle was performed. The nonuniform degree of DPP perforation of the VVER-TOI SG was selected, which provide steam velocity distribution as close as possible to the SG with ten steam nozzles. To justify the chosen design, sensitivity analysis was also carried out according to the hole diameters tolerance and steam load profile.
