Summary Report for Conduct of Kozloduy NPP Stress Tests

“Kozloduy NPP” PLC
SUMMARY REPORT
for Conduct of Kozloduy NPP
Stress Tests
occur in their structures at extreme wind. In this case, if the spray pool makeup pumps are damaged,
it is running emergency makeup of the pools of 6. ShPS in the valley of Danube River, i.e. the
safety functions are not violated.
Given that the structure of the buildings DGS is reinforced concrete ("heavy"), it can be
assumed that at calculation and sizing of the combinations for seismic impact.. Therefore, the
structure can accommodate the calculated effort under extreme wind pressure, which are close and
lower than those at a seismic impact.
4.3.2.1.5 Spray pools Units 5, 6
The design basis of spray pools are consistent with their 1 category seismic resistance and
the estimated maximum wind speed at probability p = 0.01% (once per 10,000 years) of 45 m/s.),
which meets the requirements set for normative and extreme wind speeds.
Supplementary water for spray pools, which comes from pumps CPS-3 and CPS-4 and as a
reserve - diesel pumps and ShPS, compensates for losses from spraying at weak and moderate
winds. There is a process option at extremely strong winds to eliminate losses from blowing, the
water supplied for cooling is released directly to the bottom of the spray pools without spraying in
nozzles, as its cooling is by convection.
4.3.2.2 Snowfalls
4.3.2.2.1 Main building – Reactor compartment Units 5 and 6
The calculated value of snow load (2,52 kN /m2 ) is 50% higher than the applicable
standards (1,68 kN/m2) and 57% higher that the extreme value of snow load (1.6 kN/m2). The
structure has reliable stiffness and can withstand extreme snowfall.
4.3.2.2.2 Reinforced concrete ventilation pipe
loads.
Due to the structure of the ventilation pipes they are not threatened by damage from snow
4.3.2.2.3 CPS 3 AND CPS 4, DGS-1,2 and 3 cells
The calculated value of snow load in the design basis of the buildings (0,98 кN/м2) is lower
than the current standards (1,68 КN/м2) and extreme value (1.6 kN/м2). At relatively heavy
structures, such as reinforced concrete, with high ratio of permanent loads to the snow loads the
impact of the snow load increase is minimal. The physical condition of structural elements and the
influence of a constant load is rather leading to determining the bearing capacity of the elements
and determination of sections, in which boundary deformation and loss of bearing capacity occurs.
The roofs of DGS-1,2 and 3 cells have sufficient bearing capacity to accommodate the load
of snow according to the new standards.
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