International Standard Bases and Safety Classification - Nuclear Power Plant Instrumentation and Control Systems for Safety and Security - page 42

IEC 61513 (IEC, 2011,a) uses main principles
of functional safety of basic IEC 61508, applying
I&C (Figure 4). The necessity in IEC 61513 de-
velopment, having a more common standard IEC
61508 for critical systems of various purpose, is
connected with the fact that IEC 61513 a set of
peculiarities of NPP safety assurance is taken into
account, e.g. already available hazard information,
availability of deterministic approach to determine
system importance in terms of safety and others.
It should be noted that in IEC 61508 uses the
term “safety related system.” However, in IEC
61513, devoted to NPP I&C, this term is inter-
preted as “safety important system“ according to
IAEA nomenclature (see, e.g., IAEA, 2000,a and
IAEA, 2012).
Following IEC 61508, functional safety of an
I&C system can be called as a part of “nuclear
and radiation safety of NPP” that refers to I&C
operating in common and NPP technological
equipment and depends on the I&C system cor-
rect functioning.
“Functional safety” term is relatively a new
one. This term conforms to the problem of inter-
connection between the I&C and NPP safety: just

I&C function performance affects NPP safety.
Thus, the expression “I&C functional safety
requirement” is identical to a longer expression
“I&C requirements, affecting NPP nuclear and
radiation safety.”
In Application D of IEC 61513 the interconnec-
tion between IEC 61508 and nuclear application
standards is considered.

IEC Common Technical Standards

In IEC membership there is also a range of techni-
cal committees that developed common technical
standards for different branches of technique, not
only for NPPs. TC 77 “Electromagnetic compat-
ibility” elaborated a set of standards with common
name “Electromagnetic compatibility (EMC)
- Testing and measurement techniques -” 61000-
4- and additional name and number, which takes
into account type of test (e. g. Electromagnetic
compatibility (EMC) - Testing and measurement
techniques - Electrostatic discharge immunity test
IEC 61000-4-2).
The special importance of this group of stan-
dards is explained by the fact that advanced I&C

Figure 4. Relationship between IEC standards related to functional safety in different branches of tech-
nique and related to NPP I&C