Modelling the 3D flow in the Sava river at the entrance to the inflow channel of nuclear power plant Krško and comparison with measurements

Abstract

A hydro-electric power plant (HEPP) Brežice will be built 7 km downstream of the Nuclear power plant\ud Krško (NPPK). This will cause a 3 m rise of the water level, which will change the hydraulic and thermal\ud conditions at the entrance of the cooling water to the inflow channel. The project task was to simulate the\ud velocity field and sediment transport in the future conditions at his location, and to simulate thermal\ud conditions in the entire Brežice reservoir. As the vertical velocity components in the vicinity of the inflow\ud are of the same order of magnitude as the horizontal components, the velocity field is “fully 3D”. As the\ud applied model PCFLOW3D is in the “quasi 3D” form, we performed measurements of the velocities in the\ud Sava River near the inflow to the channel. During the verification of the model we found that the model gives good results for the flow upstream of the inflow section, while near the inflow the results are less\ud reliable. We are currently preparing a “fully 3D” version of the model. The present model showed that in the\ud future conditions the sediment inflow into the inflow channel will not change significantly. Verification of\ud the thermal module had already been carried out in 1995 and 1998 on the reservoir Vrhovo in both summer\ud and in winter conditions. It was shown that the model can well simulate the thermal conditions