Environmental Engineering Reference
In-Depth Information
Chapter 2
International Standard Bases
and Safety Classiication
Michael Yastrebenetsky
State Scientiic and Technical Centre for Nuclear and Radiation Safety, Ukraine
Grygoriy Gromov
State Scientiic and Technical Centre for Nuclear and Radiation Safety, Ukraine
ABSTRACT
The main standard bases for NPP I&C systems are documents of the International Atomic Energy Agency
(IAEA) and International Electrotechnical Commission (IEC). Standards are interconnected through the
following: IAEA develops general safety principles for NPP I&C systems, and IEC develops technical
requirements that use and specify safety principles. Structures of the bases are considered. Classiications
of I&C systems and their components are given on the basis of their safety impact. According to the IAEA
classiication, all systems are divided into safety important and non-safety important. According to IEC,
functions to be performed by I&C systems shall be assigned to categories according to their importance
to safety. The importance to safety of a function shall be identiied by means of the consequences in the
event of its failure, when it is required to be performed, and by the consequences in the event of a spuri-
ous actuation. All functions are divided into categories A, B, C.
INTRODUCTION
forbidden that are not allowed. In many other
branches of industry there is a reverse statement:
those actions are allowed that are not forbidden.
Allowed actions are described in standards as NPP
safety in general, and NPP I&C that provides the
safety, in particular.
Secondly, in consideration with a global scale
of accident international cooperation is used exten-
sively in nuclear power engineering. It applies to
development and use of NPP I&C safety standards.
Standard bases of the International Atomic Energy
Agency (IAEA) and International Electrotechni-
cal Commission (IEC) are the most widespread
There is an expression that safety regulations are
written with blood. It applies foremost to standards
in nuclear power engineering, where accidents
have a large-scale effect.
Standardization in nuclear power engineer-
ing, including NPP I&C systems, has specific
peculiarities in comparison with other branches
of industry.
Firstly, in nuclear power engineering there
is a strict prohibition on any actions that are not
specified by the regulations: those actions are
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