International Standard Bases and Safety Classification - Nuclear Power Plant Instrumentation and Control Systems for Safety and Security - page 52

SHORT REMARKS ON THE
NATIONAL STANDARD BASES

of active ones, periodic redevelopment of IAEA
documents prove these statements.
Two most important directions of work on
standardization applicable to NPP I&C can be
recommended:

Every country, where there are NPP's, has its own
regulatory authority and own standard base related
as to NPP safety as whole, as to NPP I&C systems.
Comparison of different I&C safety classifica-
tions is of interest is shown at Table 3 (the basis of
this table is taken from (IAEA, 2011,b). In recent
years after issuing of IEC 61226 and its following
editions (let us note that besides IEC 61226 no
IEC standards has been issued in a third revision
over the recent 10 years) I&C systems division
into 3 classes, corresponding to division of func-
tions into 3 categories, is more widely applied.
Harmonization with IEC 61226 is performed in
the most part of European countries.
However, in Ukraine up to date safety impor-
tant I&C systems have been divided into two
safety classes (class 2 and 3). I&C systems were
not related to class 1, according to high level
document of regulatory authority of Ukraine,.
Only now new regulations, where I&C systems
are divided into 3 classes (Yastrebenetsky &
Rozen, 2010), have been developed in Ukraine.
Though, it should be noted that the proposed
I&C systems classification is not used, for ex-
ample, in the USA, where only one safety class
- 1E is determined. It includes electrical equip-
ment and systems required for emergency reactor
shutdown, isolation of containment, reactor core
cooling, heat removal from containment and
reactor or other actions important for prevention
of radioactive materials into the environment
(ANSI-IEEE). Other systems and equipment are
not related to IE class.
At present, more attention is given to harmo-
nization of international and national standards.

1. Harmonization of national and international
documents of different countries with inter-
national requirements.
2. Modification of requirements for NPP I&C,
resulting from lessons of the Fukushima-1
accident. This recommendation will be con-
sidered below in Section “Future Research
Directions” more detail.

FUTURE RESEARCH DIRECTIONS

The future research directions were pointed out
in the paper of heads of IEC TC-45 (Cox & Shu-
mov, 2010):

• Hardware, software and Commercial Of
The Shelf (COTS) items are more and
more used in instrumentation and control
systems of nuclear reactors.
• Methods of information exchange (be-
tween instruments and control rooms,
radio-links, exchange formats) are rapidly
developing.
• The Internet impacts all industries and
might need a speciic approach for nuclear
application.
• New types of reactors, such as advanced
gas-cooled reactors, Pebble Bed Modular
Reactors and reactors with higher power
levels, are built in some countries. These
types of reactors will require new types of
instrumentation and control systems.

Solutions and Recommendations

These trends either have already been taken into
account in the project of international standards
or they will be taken into account in the nearest
future project.”

International normative bases of IAEA and IEC are
sufficiently coordinated and continue developing
actively. New IEC standards and regular revisions