Geoscience Reference
In-Depth Information
water level in the lake is indispensable in order to increase lake water volume
because of the increased evaporation from heated water discharge. It was deter-
mined that the maximum water level in the lake will be 2.70 m asl and cannot be
exceeded. Minimum water level in the lake was assumed at 0.70 m asl, which was
imposed by the operation of turbines of the pumped-storage power plant. These
changes required installation of a control weir at the outflow from the lake and
additional dykes along the northern shore of the lake. Lake water volume and
surface area were estimated within levels 0.70 and 2.70 m asl.
7 Upper Reservoir
The upper reservoir of the pumped-storage power plant was constructed on the
nearby moraine hill and has the area of about 1 km
2
. Operational variation of water
levels in the reservoir is about 16 m, from 110 to 126 m asl. This gives water
volume of 13.6 hm
3
. The maximum water volume in the upper reservoir is 16 hm
3
,
and it is necessary to foresee such volume in the lake in case of emergency
emptying of the upper reservoir. The upper reservoir is water tight due to a special
asphalt lining.
8 Operation of Nuclear and Pumped-Storage Power Plants
Pumped-storage power plant operates on a weekly cycle, and there are differences
between consecutive days of the week. Maximum discharges in turbine cycle reach
about 400 m
3
/s, while in pump cycle maximum discharges reach up to 500 m
3
/s.
This results in the daily water level variation in the lake of about 1.0 m and currents
near the outlet channel reaching up to 1.0 m/s, which results in considerable mixing
in lake volume. In this situation, it is difficult to expect thermal stratification along
lake depth or important temperature variation over the lake surface.
Nuclear power plant with four units will have a maximum installed capacity of
1760MWe. With general efficiency of the nuclear power plant of 34%, the waste heat
discharged to the lake amounts to 3420MWt. This situation will result in discharge of
cooling water of about 90 m
3
/s with temperature rise in the condensers of
D
t
9.2
C.
ΒΌ
9 Water Balance of the Lake Under the Influence
of Both Power Plants
One of the main problems of the future operation of both power plants was the
water balance of the lake taking into account small inflow to the lake and additional
evaporation from lake surface due to heated water discharge. Simulation of this
