Summary Report for Conduct of Kozloduy NPP Stress Tests

“Kozloduy NPP” PLC
SUMMARY REPORT
for Conduct of Kozloduy NPP
Stress Tests
Each spray pool is designed to remove entire heat released from the unit during emergency
mode, and to maintain inlet service water temperature for safety system consumers cooling within
the range of +4 o C to +33 о С.
5.1.3.2.2 Time limitations for use of alternative heat sink and capabilities to increase the time
available
At initial water level in the given spray pool, correspondent to maximum, and at wind speed
less than 2 m/s, the pool can operate without filling during 30 hours. At this water level in it reduces
on 1.5 m. Loss due to steaming and water entrainment is 170÷175 m 3 /h.
In order to fill one spray pool to minimum permissible level 2526 m 3 of water is required,
and to maximum level – 7650 m 3 water.
Water supply to the spray pools may be provided from:
· Motor-driven pumps of service water system for cooling of normal operation system
consumers, 2 per unit, each with flowrate of 1440m 3 /h. The pumps can operate at level of
the cold channel above elevation 28 m.
· Diesel-pumps of service water system for cooling of normal operation system
consumers, 2 per unit, each with flowrate of 290 ÷ 500 m3/h. The pumps pump out virtually
from the bottom of the cold channel and may use entire emergency reserve – 52264 m 3 in
the intake chamber of CPS-3 and 21762 m 3 in the intake chamber of CPS-4.
· The pumps in shaft pumping stations, each with flowrate of 180 m3/h. The pumps
conditions:
are of two groups with diverse power supply. One pump of each group may operate in each
shaft pump station. Total flowrate to the spray pools is 1080 m 3 /h. in case of overflow of
breaking of the state dike the shaft pump stations will be flooded and their use for water
supply to the spray ponds will not be possible.
Evaluation of time to exhaust of emergency volume is done considering the following
· One channel of service water system for cooling of nuclear-service consumers is
sufficient to remove decay heat from the reactor and SFP;
· One pair of spray pools ensures cooling of per one safety system train of two units 5
and 6.
Assuming that at the start of water supply to the ponds, they are empty (water was drained
completely) in order to fill the pair of the ponds to minimum level at which they are operable,
2х2526 = 5052 m 3 of water is required. Time required for that is:
· 53 min with motor-driven pumps of service water system;
· 2 h 35 min with diesel pumps of service water system.
To replenish for loss due to steaming and water entrainment in one pair of spray pools (340
– 350 m3/h), operation of one of the motor-driven pumps or one of the diesel pumps is sufficient.
149/202