NPP: Power Grid Mutual Safety Assessment - Nuclear Power Plant Instrumentation and Control Systems for Safety and Security - page 421

Table 7. Fragment of Siberian power systems criticality tuple (before accident)

Type of influence

Power Grid system Physical Informational Geographic Organizational

Criticalities caused by the given type of influence

Total criticality

Sayano-Shushenskaya HPP M L L L H

Mayansk HPP L L L L L

Bratskaya HPP M M L M M

Bratsk TPP L H L L M

Table 8. Fragment of Siberian power systems criticality tuple (nearly to accident)

Type of influence

Power Grid system Physical Informational Geographic Organizational

Criticalities caused by the given type of influence

Total criticality

Sayano-Shushenskaya HPP H M L H H

Mayansk HPP H M L M M

Bratskaya HPP L M L M M

Bratsk TPP L H L L M

APPROACH TO NPP SAFETY
ASSESSEMENT COMBINING FUZZY
MODELS AND BAYESIAN BELIEF
NETWORKS UNDER UNCERTANTIES

uncertainty and mutual influence of systems. BBN
is used to predict the particular criticality of the
PG system conditioned by the given type of influ-
ence. CWW is suggested to determine the total
PG system criticality. The proposed technique
may be applied to the power grid safety analysis
considering the different types of influences be-
tween NPP and other power grid systems. Results
of the analysis may be used to determine effective
safety management strategies.
Consideration of the difference types of influ-
ence allows improving the accuracy of PG safety
value.
Next step of the technique enhancement will be
related to consideration of Ukrainian NPP safety
analysis taking into consideration the types of
influences of the power grid and development of
the decision making tool-based system.

The problem of NPP and its systems (as an ex-
ample, NPP I&C systems) safety assessment is
topical due to importance of current tasks. Thus,
for example, NPP safe operation is critical for the
strategy of country industrial development and
the growth of welfare of its citizens. Fukushima-1
NPP accident showed that the CI reliability and
safety level contributes to the public confidence
in them, which in turn has a direct impact on the
length of their life cycle, their modernization and
reconstruction projects financing level. The set
of input data used in the analysis of NPP safety
includes:

• Deterministic Data (D d ): An information
set giving a credible description of NPP
(speciications, operating parameters and