Summary Report for Conduct of Kozloduy NPP Stress Tests

“Kozloduy NPP” PLC
SUMMARY REPORT
for Conduct of Kozloduy NPP
Stress Tests
2.1.4 Initial seismic design bases of DSFS
DSFS has been designed and constructed after 1992 and its design incorporated actual
seismic characteristics of the site defined in 1992:
· OBE Seismic Level-1 with peak ground acceleration (PGA) of 0.10 g with
recurrence period of 100 years
· DBE Seismic Level-2 (DBE) with peak ground acceleration (PGA) of 0.20 g with
recurrence period of 10000 years.
2.2 CURRENT SEISMIC DESIGN BASES – RLE OF KOZLODUY NPP
Current seismic characteristics of Kozloduy NPP site were defined during the period from
1990 to 1992 and are valid for all facilities in the site.
2.2.1 Reassessment of seismic design bases
For Kozloduy NPP during the period from 1990 to 1992 under a joint project with the IAEA
- BUL 9/012 “Site and Seismic Safety of Kozloduy and Belene NPPs” new seismic characteristics
of the site were defined and the influences of local earthquakes and other specific parameters were
additionally analyzed. Using probabilistic and deterministic methods the seismic levels have been
defined for the recurrence period respectively 100 and 10000 years based on the tectonic,
geological, geomorphologic, seismic and geophysical data. Thus, the following has been identified
for Kozloduy NPP site:
· For level with recurrence period of 100 years peak ground acceleration (PGA) is
0.10g and
· For level with recurrence period of 10000 years peak ground acceleration (PGA) is
0.20g.
· Design floor response spectra and respective 3D acccelerograms with duration of
61s.
Following the IAEA recommendation additionally impact of a local earthquake has been
studied. Floor response spectra from the local earthquakes and respective 3D accelerograms (with
duration of 20 s) have been defined.
The seismic characteristics – seismic levels, design floor response spectra and respective 3d
accelerograms were reviewed and confirmed by IAEA experts during the period from 1992 to 2008.
Also, the so called review level earthquake (RLE) has been defined. This is the level for
which all 1 st seismic category SSCs are reviewed for the plants already designed (which is the case
of Kozloduy NPP).
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