Summary Report for Conduct of Kozloduy NPP Stress Tests

“Kozloduy NPP” PLC
SUMMARY REPORT
for Conduct of Kozloduy NPP
Stress Tests
MWL for Kozloduy NPP site is defined at 32,93m at current condition of hydro-technical
structures by Danube River. The scenario involving occurrence of this water level is sudden and
sequential break of water supply systems “Iron gates” 1 and 2 with overlapping of the two waves
and water quantity 10000 m3/s. Additional supplements are taken for local rainfall and waving.
The following analyses of the plant safety are performed for MWL = 32,93m.
The natural water levels in the detailed design of Kozloduy NPP are obtained empirically
with the observation data in their basis have confidence greater than 1%. At the next stage levels
and flows with confidence 0.5%, 0.1% and 0.01% were obtained by extrapolation. The study of the
maximum water levels at these low probabilities is accompanied by overflow of protection dikes.
Overflow of the dikes is likely to start higher along Danube River, in Timok, Vidin, Orsoya and
Tsibar. The same will be with the Romanian dikes, as well as according to the studies from 2010
[106]. Dependencies of water levels in the likelihood, where the level exceeds the elevation of the
dike (32,00 m for Kozloduy NPP) will differ from the water levels with larger probabilities and
lower levels, namely due to overflow of protection dikes which radically alter the area flooded. For
the natural waters in Danube River with probabilities 10-5 to 10-7 water levels anticipated are as
follows:
Potential to reach 10 -5 10 -6 10 -7
Water level 32,40
m
32,60
m
32,70
m
Based on the water levels in natural state of Danube River defined this way the combination
of two events - natural extreme water levels at small probabilities (10-5 to 10-7) and rupture of
water supply system "Iron Gate" 1 and 2 can also be assessed. It should be noted that combining the
two scenarios will lead to an with a very low probability of occurrence. The water levels anticipated
are as follows:
Potential to reach 10 -5 10 -6 10 -7
Water level 32,98
m
33,26
m
33,42
m
These results also confirm the accepted assumption that Kozloduy NPP is "NON
FLOODING".
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