Summary Report for Conduct of Kozloduy NPP Stress Tests

“Kozloduy NPP” PLC
SUMMARY REPORT
for Conduct of Kozloduy NPP
Stress Tests
In case of loss of off-site power supply safety-related consumers are powered from independent
emergency power supply sources located at area of units 5 and 6.
· Emergency DGs
Each of the units 5 and 6 has three automated diesel-generators, per one for each of the
safety system trains. According to section 3 and section 8 of [7] and [8], the diesel generators are
class 3 by OPB-88/97 and IAEA definition for safety functions, respectively, class Е1 by IEEE, and
comply with respective seismic category 1. They are located at the site level. Consumers which are
supplied from emergency DGs are safety systems, SFP cooling pumps and fire-protection pumps.
· Accumulator batteries
Power to the first category consumers during all operational modes, including complete loss
of power supply mode, is provided from the accumulator batteries. Accumulator batteries energize
the I&C in the reactor compartment, primary steam-gas mixture emergency removal system, BRU-
A and emergency lighting.
Reliable power supply system for the bank pumping station is intended to supply power to
consumers related nuclear and fire safety (emergency service water pumps, shaft pumping stations,
fire-annunciation installation and fire extinguishing in BPS and their supporting systems). Dieselgenerator
station in the BPS is equipped with two diesel-generator sets.
There are two accumulator batteries installed in the BPS which serve to guarantee
uninterrupted power supply to the most important consumers ensuring accident-free operation of
facilities in the BPS shop.
5.1.1.1.2 Independency of emergency power supply and measures to prolong operational time
period
· Emergency DGs – At operation of two emergency DGs (one per the unit) total capacity of
fuel and oil of the emergency DGs is sufficient for more than 38 days.
· Accumulator battery – No need to undertake measures to prolong operational time period of
the accumulator batteries. See description in par. 1.3.2.6.1. „Accumulator batteries“.
· DG of the BPS – Total reserve of fuel and oil at the BPS site ensure uninterrupted operation
of both DGs during 56 hours and 45 minutes.
5.1.1.2 Loss of off-site power supply and loss of emergency diesel-generators
5.1.1.2.1 Design schemes of permanently installed sources of additional emergency power
supply to the site, capacity and availability for putting into operation
Each of the two units has one additional independent diesel-generator with nominal power
of 5.2 MW. According to the design these DGs are intended to ensure voltage to normal power
supply busbars, through which – in case of loss of secondary circuit normal make-up – heated water
is supplied to the SG from the deaerators, instead of cool water from the reservoirs of the secondary
circuit emergency make-up system. In the same way thermal stresses in the SG tubing are
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