Summary Report for Conduct of Kozloduy NPP Stress Tests

“Kozloduy NPP” PLC
SUMMARY REPORT
for Conduct of Kozloduy NPP
Stress Tests
Batteries of the safety systems of the two units, with the exception of the second system of
unit 5, are assembled with type 106 cells, sequentially connected. The capacity of one battery is
1133A/h for 10-hour value. The service life is 240 months 196.
The battery of the second system of Unit 5 is equipped with 106 battery elements, type Vb-
2412, sequentially connected and mounted on seismic metal racks. Battery capacity is 1200/h at 10
hour discharge to 1,8V of element at 20°C. The service life is 240 months [23].
All safety system batteries of both units are mounted on seismically qualified metal racks.
When performing real tests on the battery of the second train of the safety system for unit 5
all possible loads are actuated in station blackout mode, the battery supplies power to these loads for
10 hours and 18 minutes, until voltage reaches 191V. The battery should automatically trip at 180 V
and at continuous extrapolation it is estimated that the battery can last up to 11 hours and 32
minutes.
The actual system load is approximately 250 A with which the battery can be discharged.
For power supply of the equipment required for startup of emergency diesel generators
nickel-cadmium rechargeable batteries with a nominal capacity of 270A\h in 10-hour discharge are
used.
1.3.2.6.2 Loads supplied from the batteries
There are two types of loads – loads powered with DC power and those powered with AC
power. In normal operation the batteries are in recharging mode and the battery itself and the loads
are powered from 2 nd or 3 rd category in rectifier.
The loads DC power supply is through direct current board. From the buses of the safety
systems direct current board respective devices for relay protections, control and signalling, devices
for safety systems automation, automation and signalling for fire alarm and fire fighting, emergency
lighting, etc. are powered [24]. From direct current board of the respective diesel generator startup
systems, DG control and auxiliary equipment, emergency lighting and fire alarm are powered.
The loads AC power supply is through inventers. The loads powered this way include I&C,
safety related valves, etc.
1.3.2.6.3 Location and distribution of the batteries. Protection against external and internal
impacts
The batteries of the safety systems are located at the elevation of 13,20 in the reactor
building, in the rooms of respective system. Geographically they are separated from each other.
one another.
The batteries to the respective DG are located in the respective diesel cell, independently on
These batteries meet all requirements of I category equipment, i.e. physical separation,
independence, lack of connection between different trains, seismic reinforcement, limited access,
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