Properties of Safety Important I&C Systems and their Components - Nuclear Power Plant Instrumentation and Control Systems for Safety and Security - page 115

IEEE Std 323 (2003). Qualifying Class 1E Equip-
ment for Nuclear Power Generating Stations.

Diversity: A property related to a group of two
or more I&C systems and SHC, which simultane-
ously and independently from each other perform
functions identical for achieved safety purposes,
and differ from each other by the operating prin-
ciple, structure, applied component parts, software
and / or other attributes or achieve the target goal
in different ways.
External Influencing Factors (EIF): Factors,
which can occur in places of hardware r location
and include: EIF environment (temperature, hu-
midity, barometric pressure, ionizing radiation,
corrosive agents, dust), mechanical EIF (vibra-
tions, strokes, seismic effects), EIF power supply,
EIF spe cific environments (water and solutions,
which can affect devices in accidents and to
decontamination fluids), . electromagnetic EIF.
Redundancy: Application of additional
means and / or possibilities, redundant in regard
to those, that are minimally required for function
performance.
Single Failure Criterion of I&C Systems
and SHC: Criterion which requires performing
all specified functions in any postulated initiating
event (PIE), with combination of failure of one
(any) element independent of this PIE.

IEEE Std 344 (2004). Recommended Practice for
Seismic Qualification of Class 1E Equipment for
Nuclear Power Generating Stations.

IEEE Std 344 (2004). Recommended Practice for
Seismic Qualification of Class 1E Equipment for
Nuclear Power Generating Stations.

IEEE Std 384 (2008). Standard Criteria for Inde-
pendence of Class 1E Equipment and Circuits.

IEEE Std 627 (2010). IEEE Standard for Quali-
fication of Equipment Used in Nuclear Facilities.

Yastrebenetsky, M., Rozen, Y., Klevtsov, A., et
al. (2012) Fukushima accident lessons for I&C
systems (Ukrainian experience, first steps). 8 th
International Topical Meeting on Nuclear Plant
Instrumentation, Control, and Human Machine
Interface Technologies (NPIC & HMIT), San
Diego, USA.

KEY TERMS AND DEFINITIONS

Common Cause Failures: A simultaneous
failure of two or more elements in different re-
dundant parts due to the same cause, which can
result in a failure of I&C function.