Summary Report for Conduct of Kozloduy NPP Stress Tests

“Kozloduy NPP” PLC
SUMMARY REPORT
for Conduct of Kozloduy NPP
Stress Tests
1.6.1.3 Reliability of off-site power supply
In the electric energy system “Plan for EES recovery following a severe accident” is in
force. According to this plan at collapse of the EES, voltage is to be supplied to Kozloduy NPP by 4
possible corridors. The corridors are powered from sources with possible zero start – HPP and
neighbouring EES. In Kozloduy NPP procedures for personnel actions are approved for starting the
option under the plan for distribution of the resulting voltage and power supply to units and BPS
auxiliaries.
1.6.2 Bank pump stations (BPS) and channels
For the needs of Kozloduy NPP in august 1974 bank pump station - 1, cold and hot water
channels and circulation pump station 1 were commissioned, together with plant service water
systems. Later bank pump stations -2 and 3 with general supply channel and circulation pump
stations - 2, 3 and 4 with the required pipelines, closed low pressure channels, spray ponds and
other facilities were constructed. The structures in BPS-2 and BPS-3 are the modified variant of the
structures in BPS-1, with the motors of the pump sets set at a higher elevation for failure free
operation at potential construction of water power system Nikopol – Turno Magurele.
1.6.2.1 The site location and specific features
The bank pump stations (BPS) 1, 2 and 3 are located on flat terrain (at km 687 of Danube
River), at a lower terrace, to the site of Kozloduy NPP and circulation pump stations (CPS) are
constructed in the area of Kozloduy NPP. The site has been selected so that to avoid to the
maximum extent possible sediment deposition and river level fluctuation.
1.6.2.2 Main data of BPS and channels
The water of Danube River falls into the supply channel that takes it to the specially formed
chambers (advance chambers) located before BPS 1,2 and 3. The advance chambers ensure smooth
transition to the suction holes of thirty seven water bank pumps. The number of water pumps in
operation depends on the moment of the plant power and Danube River level.
Pumped water from the pump units, within the cast facilities, which are in the outlet
chambers of pressure pipelines. Each chamber has a metal enclosure – structures used for drying of
certain sections. By means of this structure it is possible to supply water from the hot channel to the
advance chambers to avoid freezing of water in them in winter.
In the pressure pipelines water is supplied to the so called cold channel, by which it
gravitationally reaches circulation pump stations ensuring service water supply to the nuclear
facilities. The cold channel has length of 7023 m and depth of 5. 60 m, with trapezoidal cross
section of bottom width 20 m. The last section of the cold channel with length of 950 m is located
on Kozloduy NPP site and and is entirely built in a trench and separated by seismically qualified
overflow barrier intended to prevent from lowering of the level in this area.
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