Summary Report for Conduct of Kozloduy NPP Stress Tests

“Kozloduy NPP” PLC
SUMMARY REPORT
for Conduct of Kozloduy NPP
Stress Tests
Additional system for steam generator emergency makeup (ASSGEM-3) of unit 3 and
ASSGEM-4 of unit 4, and Fire Pump Station 2 were designed and put into service before 1997 as a
system of seismic category I and are designed for seismic effects of DBE level.
The wind load calculated in the design basis (1.40 kN/m2) of the three buildings is greater
than the extreme value (1.24 kN/m2) of these standards. The available margin is within 2.6%,
taking into account the significance factor according to the current standards and elastic work of the
structures.
4.3.1.1.3 Reinforced concrete ventilation pipes 1 and 2
In 1999 a constructive investigation of "Energoproekt" LLC of the three reinforced concrete
pipes at the site was performed identifying that the facilities are designed for the effects of wind
with calculated load from 1,26 kN/m2 exceeding the extreme values of 1.24 kN/m2 of these norms.
The facilities have the required carrying capacity to bear the normative and extreme wind
load as the design value of the wind is 88% higher as compared against the normative value and
1.6% against the extreme value the wind.
4.3.1.1.4 Spray pools 3,4 unit
Design basis of the three spray pools comply with their first class in seismic resistance and
the calculated maximum wind speed of 45 m/s (load - 1.24 kN/m2) at probability P = 0.01% (once
per 10 000 years), which meets the requirements of the regulations and specified extreme wind
speeds.
Losses of water treatment during extreme winds do not affect the performance of the system
safety function (ultimate heat sink) as the system is open and has a continuous makeup from the
advance chamber before CPS-2.
4.3.1.2 Snowfalls
4.3.1.2.1 Units 3 and 4 – Reactor compartment
The design basis for the calculated extreme snow loads (2.52 kN/m2) exceed the standard
calculated value of these standards (1.68 kN/m2).
Facilities have the necessary carrying capacity to withstand standard and extreme snow
loads as the design calculated value of snow load is higher than 50% as compared against the
normative value and 57% as compared against the extreme values of snow load.
4.3.1.2.2 ASSGEM 3 and 4, FPS 2, CPS 2 AND DGS 2
The design snow load in the design basis (1.40 kN/m2) is less than the defined extreme (1.6
kN/m2) and standard (1.68 kN/m2) value. In relatively heavy structures such as reinforced concrete,
with a high ratio of permanent loads to the snow loads, the impact of the increase of snow is
minimal. The physical condition of structural elements and the influence of a constant load is rather
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