NPP: Power Grid Mutual Safety Assessment - Nuclear Power Plant Instrumentation and Control Systems for Safety and Security - page 404

to subsequent ef fec t on anot her
components;
6. Societal influence I

tween standby system and the system it is
supporting;
• Cyber inluences via control systems;
• Spatial Inluences: Refers to equipment
within small distance to each other;
• Human Inluences: Refers to all activities
with human participation.

NPP ( ) that PG compo-
nents may have on societal factors as public
opinion, fear and confidence.

t

soc

Mutual PG-NPP safety influence is shown
on Figure 1. It is worth to note that influence
exists on all grid levels and has to be taken into
consideration when providing grid systems safety.
There are some influence types on lower lev-
els of NPP-PG's hierarchy.
All influences of subsystem's level might be
divided in following categories:

Influences Formalization

As we see, there are a lot of different types of
influences, which exist on all NPP-PG hierarchy's
levels. Though these influences create opportuni-
ties, they also create new vulnerabilities. These
vulnerabilities may produce adverse impacts that
are becoming more widespread and more frequent.
In order to provide stable and safe operation
of NPPs, a systematic way of formalization and
evaluating these influences are needed.
The influences between different systems of
PG could be described (or formalized) by means of
the Influence vector (Brezhnev et al., 2011). The
Influence vector is characterized by the value and
direction. The direction points the initial source

• Functional Inluence: Connected equip-

ment encompasses NPP and other PG's el-
ements design involving shred equipment,
common input, loop dependencies plus sit-
uations, in which the same equipment pro-
vides multiple functions. Nonconnected
equipment encompasses interrelated suc-
cess criteria such as the relationships be-

Figure 1. Mutual PG-NPP safety influence