Summary Report for Conduct of Kozloduy NPP Stress Tests

“Kozloduy NPP” PLC
SUMMARY REPORT
for Conduct of Kozloduy NPP
Stress Tests
Table 1.7-1: Level 1 PSA results.
Internal IEs Internal fires Internal
floodings
Seismic
impact
Total
Core damage frequency
with unit power
operation, /year.
Core damage frequency at
low power operation,
/year
SFP fuel damage
frequency/year
Total, events/ reactor
years.
9,32E-06 3,11E-06 1,98E-07 3,34E-06 1,6E-05
5,22E-06 1,98E-07 2,94E-08 3,66E-09 5,45E-06
1,50E-06 1,21E-07 1,67E-09 1,66E-08 1,64E-06
1,60E-05 3,43E-06 2,29E-07 3,36E-06 2,30E-05
External initiating events other than seismic effects are not accounted for in the PSA. In
Chapter 2.2, "Human induced conditions for the deployment of NPP" [7],[8], are considered
potential sources of hazard to the site of human induced character in the area within a radius of 30
km from the NPP site - possible sources of accidents in industry and transport, in special facilities,
hydraulic structures, quarries and landslides, gas stations, environmental parameters.
Probabilistic Safety Assessment Level 2 is being updated and available results are not
updated. Scope of the analysis is the same as in level 1 PSA. Model of PSA level-2 for units 5 and 6
of Kozloduy NPP reflects the actual status of the units by 2001, i.e. there are no reported measures
for the modernization program. Within modernization additional facilities are built that will have a
huge impact as to prevent containment failure and on the disposal of radioactive fission products
into the environment. The results for 5 and 6 units of Kozloduy NPP received in 2001 and updated
by the time indicate frequency value of large early releases (LERF) of 5. 37Е-06 1/year.
On the basis of PSA Risk Monitor was developed, which is used in everyday operation of
Kozloduy NPP. Furthermore, other PSA applications are also developed or are under development -
risk-informed testing, risk-informed maintenance, risk-informed Technical Specifications [36].
1.7.3 Scope and main results of SFS PSA
Full scope probabilistic safety assessment for SFS has not been completed. There is safety
analyses for a whole range of potential initiating events performed using potential hazard and
operability analysis method (HAZOP) [37].
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