Summary Report for Conduct of Kozloduy NPP Stress Tests

“Kozloduy NPP” PLC
SUMMARY REPORT
for Conduct of Kozloduy NPP
Stress Tests
5 km and М=5.0 at 5.0 km distance and 5.0 km depth on the structures and equipment have been
studied separately.
2.3 ASSESSMENT OF CONSISTENCY OF SEISMIC DESIGN BASES REASSESSMENT
OF KOZLODUY NPP SITE
All aspects and stages of the reassessment of the seismic characteristics are discussed during
multiple missions involving IAEA experts and lead specialists in the industry in Bulgaria,
Macedonia and Romania, as well as representatives of NRA and Kozloduy NPP. The assessments
provided in the final reports of the IAEA missions are conducted during the period from 1992 to
2002 can be accepted as sufficient to certify consistency of the seismic design basis. Indirectly, such
seismic input is validated and adopted in the evaluation of follow-up actions with international
participation which were considered and approved by international experts of the missions
organized.
2.3.1 Compliance with applicable documents and standards
The site seismic characteristics reassessment has been performed mainly based on IAEA
Safety Standard [40]. After implementation of the comparative analysis based on the state-of-the-art
standard [42] and the one actual during [40] it has been identified that the seismic characteristics
reassessed in 1992 with additional studies in 1995 meet the requirements of both applicable
document [42] and regulation [43] enforced in 2004 as follows:
· the site shall not be located directly on an capable fault;
· the condition of peak ground acceleration less than 0.4g on the free surface at
earthquake (PGA) with recurrence period of 10000 years shall be met.
2.3.2 Conclusion for consistency of the current design bases
Kozloduy NPP site seismic characteristics reassessed in 1992 with additional studies
performed in 1995 for local earthquakes and probabilistic definition of seismic impact on the entire
seismic PSA [34] meet the requirements of current normative framework. The requirements of [43]
are performed as follows:
· in the study of the area of Kozloduy NPP site there are no major fault structures with
high energy potential (no evidence of capable fault);
· Kozloduy NPP site is defined for a level of PGA with recurrence period of 10000
years and PGA 0.2g.
2.4 PROVISIONS MADE FOR PROTECTION AT RLE OF UNITS 3 AND 4
The analysis performed [44] is based on the documents applicable at the moment. The
review and assessment mainly used SAR ([16] and [17]) and PSA [34] and available technical
reports for analyses and expertises, qualified documents, technical passports of equipment. They
used available lists of equipment required for the unit safe shutdown SSEL (Safe Shutdown
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