Summary Report for Conduct of Kozloduy NPP Stress Tests

“Kozloduy NPP” PLC
SUMMARY REPORT
for Conduct of Kozloduy NPP
Stress Tests
1.3.2.3.3 Availability of heat removal logics and measures to extend the systems operability
The pumps, heat exchangers and the equipment of each channel of the SFP cooling system
are located in a separate room, which provides physical separation and impossibility of simultaneous
common cause failure of two or more channels. Each system is able to perform its functions with
account of single failure.
1.3.2.3.4 Heat removal systems AC and DC power supply
Electric power supply to the active components for each train of the safety systems for SFP
cooling is ensured for uninterruptible power supply І and ІІ category is from respective train of the
system for І and ІІ categories uninterruptible power supply.
1.3.2.3.5 Alternative logics and equipment cooling
In emergency modes with containment isolation removal of the residual heat from the fuel
stored can be provided in two ways: by pool water evaporation and by supply of water to the spray
system pool.
In emergency modes with containment isolation isolating valves of the head and suction
pipelines of SFP cooling system close and the system does not operate. The head pipelines of the
system are connected with the spray system head pipelines, while the valves located on these lines
are always closed. At containment pressure increase (when the isolation valves are closed) locking
of opening of these valves is automatically removed and cooling of the SFP is provided through
water supply the spray pumps head and the water overflow to the EMT. This can be achieved before
the pool water evaporation. In this case, to prevent from unacceptable reduction of fuel compartment
level and uncovering of the fuel, emergency makeup from spray system is also used.
1.3.2.4 Heat removal from containment area to the ultimate heat sink
1.3.2.4.1 Heat removal logics from the containment area to the main ultimate heat sink
In normal operation mode heat removal from containment system is performed through
ventilation systems for containment system cooling, whose air-coolers are cooled from essential
components service water supply system.
At accidents associated with containment system pressure increase heat is removed by spray
system and then to the channels of essential components service water supply system.
1.3.2.4.2 Heat removal systems
Spray System.
The system is designed to localize accidents through condensation of the evaporated part of
the coolant released from the containment.
The system also performs the following functions:
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