Nuclear power plants - Instrumentation and control important to safety - Classification of instrumentation and control functions

IEC 61226:2009 establishes a method of classification of the information and command functions for nuclear power plants, and the instrumentation and control systems and equipment that provide those functions, into categories that designate the importance to safety of the function. The resulting classification then determines relevant design criteria. Is applicable to all the information and command functions and the instrumentation and control systems and equipment that provide those functions. The main changes with respect to the previous edition are listed below: - to introduce a definition for 'non-hazardous stable state'; - to clarify limits of categories; - to clarify requirements related to equipment used for beyond design events.

Kernkraftwerke - Leittechnische Systeme mit sicherheitstechnischer Bedeutung - Kategorisierung leittechnischer Funktionen

Centrales nucléaires de puissance - Instrumentation et contrôle-commande importants pour la sûreté - Classification des fonctions d'instrumentation et de contrôle-commande

La CEI 61226:2009 établit une méthode de classement des fonctions d'information et de commande des centrales nucléaires de puissance et des systèmes d'instrumentation et de contrôle-commande (I&C) et matériels qui assurent ces fonctions en catégories indiquant l'importance pour la sûreté de la fonction. Le classement qui en résulte permet alors de déterminer les critères de conception appropriés. Est applicable à toutes les fonctions d'information et de commande, à tous les systèmes d'I&C et les matériels supports de ces fonctions. Les modifications techniques majeures par rapport à l'édition précédente sont les suivantes: - introduction d'une définition pour 'état contrôlé'; - clarification des limites des catégories; - clarification des exigences portant sur les matériels utilisés hors dimensionnement.

Jedrske elektrarne - Merilna in nadzorna oprema za zagotavljanje varnosti - Klasifikacija funkcij merilne in nadzorne opreme (IEC 61226:2009)

Ta mednarodni standard vzpostavlja metodo klasifikacije merilnih in nadzornih funkcij za jedrske elektrarne, in merilnih in nadzornih sistemov in opreme za zagotavljanje te funkcije, v kategorije, ki funkciji pripisujejo pomembnost za zagotavljanje varnosti. Posledična klasifikacija nato določa ustrezna merila za načrtovanje. Merila za načrtovanje so ukrepi kakovosti, s katerimi se zagotovi ustreznost vsake funkcije glede na njeno pomembnost za zagotavljanje varnosti elektrarne. V tem standardu so merila funkcionalnosti, zanesljivosti, učinkovitosti, okoljske trajnosti (vključno s potresno) in zagotavljanja kakovosti (QA). Ta standard se uporablja za vse informacijske in nadzorne funkcije ter merilne in nadzorne sisteme in opremo za zagotavljanje te funkcije. Obravnavane funkcije, sistemi in oprema zagotavljajo avtomatsko zaščito, nadzor z zaprto ali odprto zanko ter obveščanje operativnega osebja. Stanje v jedrski elektrarni ohranjajo znotraj varnega operativnega ovoja in zagotavljajo avtomatske ukrepe ali omogočijo ročne ukrepe, ki preprečijo ali ublažijo nesreče ali ki preprečijo ali minimizirajo radioaktivne izpuste na lokaciji ali v širše okolje. Funkcije merilne in nadzorne opreme, ki izpolnjujejo te naloge, varujejo zdravje in varnost operaterjev jedrskih elektrarn in javnosti.

General Information

Status
Published
Publication Date
11-Mar-2010
Drafting Committee
Parallel Committee
Current Stage
6060 - Document made available
Due Date
12-Mar-2010
Completion Date
12-Mar-2010

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SLOVENSKI STANDARD
SIST EN 61226:2010
01-september-2010
Jedrske elektrarne - Merilna in nadzorna oprema za zagotavljanje varnosti -
Klasifikacija funkcij merilne in nadzorne opreme (IEC 61226:2009)

Nuclear power plants - Instrumentation and control important to safety - Classification of

instrumentation and control functions (IEC 61226:2009)
Kernkraftwerke - Leittechnische Systeme mit sicherheitstechnischer Bedeutung -
Kategorisierung leittechnischer Funktionen (IEC 61226:2009)

Centrales nucléaires de puissance - Instrumentation et contrôle-commande importants

pour la sûreté - Classification des fonctions d'instrumentation et de contrôle-commande

(CEI 61226:2009)
Ta slovenski standard je istoveten z: EN 61226:2010
ICS:
27.120.20 Jedrske elektrarne. Varnost Nuclear power plants. Safety
SIST EN 61226:2010 en

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

---------------------- Page: 1 ----------------------
SIST EN 61226:2010
---------------------- Page: 2 ----------------------
SIST EN 61226:2010
EUROPEAN STANDARD
EN 61226
NORME EUROPÉENNE
March 2010
EUROPÄISCHE NORM
ICS 27.120.20
English version
Nuclear power plants -
Instrumentation and control important to safety -
Classification of instrumentation and control functions
(IEC 61226:2009)
Centrales nucléaires de puissance - Kernkraftwerke -
Instrumentation et contrôle-commande Leittechnische Systeme
importants pour la sûreté - mit sicherheitstechnischer Bedeutung -
Classification des fonctions Kategorisierung leittechnischer
d'instrumentation Funktionen
et de contrôle-commande (IEC 61226:2009)
(CEI 61226:2009)

This European Standard was approved by CENELEC on 2010-03-01. CENELEC members are bound to comply

with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European Standard

the status of a national standard without any alteration.

Up-to-date lists and bibliographical references concerning such national standards may be obtained on

application to the Central Secretariat or to any CENELEC member.

This European Standard exists in three official versions (English, French, German). A version in any other

language made by translation under the responsibility of a CENELEC member into its own language and notified

to the Central Secretariat has the same status as the official versions.

CENELEC members are the national electrotechnical committees of Austria, Belgium, Bulgaria, Croatia, Cyprus,

the Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy,

Latvia, Lithuania, Luxembourg, Malta, the Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia,

Spain, Sweden, Switzerland and the United Kingdom.
CENELEC
European Committee for Electrotechnical Standardization
Comité Européen de Normalisation Electrotechnique
Europäisches Komitee für Elektrotechnische Normung
Central Secretariat: Avenue Marnix 17, B - 1000 Brussels

© 2010 CENELEC - All rights of exploitation in any form and by any means reserved worldwide for CENELEC members.

Ref. No. EN 61226:2010 E
---------------------- Page: 3 ----------------------
SIST EN 61226:2010
EN 61226:2010 – 2 –
Foreword

The text of the International Standard IEC 61226:2009, prepared by SC 45A, Instrumentation and control

of nuclear facilities, of IEC TC 45, Nuclear instrumentation, was submitted to the CENELEC formal vote

for acceptance as a European Standard and was approved by CENELEC as EN 61226 on 2010-03-01.

Attention is drawn to the possibility that some of the elements of this document may be the subject of

patent rights. CEN and CENELEC shall not be held responsible for identifying any or all such patent

rights.
The following dates are proposed:
– latest date by which the EN has to be implemented
at national level by publication of an identical
national standard or by endorsement
(dop) 2011-03-01
– latest date by which the national standards conflicting
with the EN have to be withdrawn
(dow) 2013-03-01
Annex ZA has been added by CENELEC.

As stated in the nuclear safety Directive 2009/71/EURATOM, Chapter 1, Article 2, item 2, Member States

are not prevented from taking more stringent safety measures in the subject-matter covered by the

Directive, in compliance with Community law. In a similar manner, this European Standard does not

prevent Member States from taking more stringent nuclear safety measures in the subject-matter covered

by this European Standard.
__________
---------------------- Page: 4 ----------------------
SIST EN 61226:2010
– 3 – EN 61226:2010
Endorsement notice

The text of the International Standard IEC 61226:2009 was approved by CENELEC as a European

Standard without any modification.

In the official version, for Bibliography, the following notes have to be added for the standards indicated:

IEC 61508-1 NOTE Harmonized as EN 61508-1.
IEC 61508-2 NOTE Harmonized as EN 61508-2.
IEC 61508-3 NOTE Harmonized as EN 61508-3.
IEC 61508-4 NOTE Harmonized as EN 61508-4.
__________
---------------------- Page: 5 ----------------------
SIST EN 61226:2010
EN 61226:2010 – 4 –
Annex ZA
(normative)
Normative references to international publications
with their corresponding European publications

The following referenced documents are indispensable for the application of this document. For dated

references, only the edition cited applies. For undated references, the latest edition of the referenced

document (including any amendments) applies.

NOTE Where an International Publication has been modified by common modifications, indicated by (mod), the relevant EN/HD

applies.
Publication Year Title EN/HD Year
IEC 60671 2007 Nuclear power plants - Instrumentation and -
control systems important to safety - Surveillance
testing
IEC 60709 - Nuclear power plants - Instrumentation and -
control systems important to safety - Separation
IEC 60780 - Nuclear power plants - Electrical equipment of the -
safety system - Qualification
IEC 60812 - Analysis techniques for system reliability - EN 60812 -
Procedure for failure mode and effects analysis
(FMEA)
IEC 60880 2006 Nuclear power plants - Instrumentation and EN 60880 2009
control systems important to safety - Software
aspects for computer-based systems performing
category A functions
IEC 60964 - Nuclear power plants - Control rooms - Design EN 60964 -
IEC 60965 - Nuclear power plants - Control rooms - -
Supplementary control points for reactor shutdown
without access to the main control room
IEC 60980 - Recommended practices for seismic qualification - -
of electrical equipment of the safety system for
nuclear generating stations
IEC 60987 - Nuclear power plants - Instrumentation and EN 60987 -
control important to safety - Hardware design
requirements for computer-based systems
IEC 61000-4 Series Electromagnetic compatibility (EMC) - EN 61000-4 Series
Part 4: Testing and measurement techniques
IEC 61000-6-2 - Electromagnetic compatibility (EMC) - EN 61000-6-2 -
Part 6-2: Generic standards - Immunity for
industrial environments
IEC 61513 2001 Nuclear power plants - Instrumentation and - -
control for systems important to safety -
General requirements for systems
---------------------- Page: 6 ----------------------
SIST EN 61226:2010
– 5 – EN 61226:2010
Publication Year Title EN/HD Year
IEC 61771 - Nuclear power plants - Main control-room - - -
Verification and validation of design
IEC 61772 - Nuclear power plants - Control rooms - Application - -
of visual display units (VDUs)
IEC 61839 - Nuclear power plants - Design of control rooms - - -
Functional analysis and assignment
IEC 62138 - Nuclear power plants - Instrumentation and EN 62138 -
control important for safety - Software aspects for
computer-based systems performing category B
or C functions
IAEA NS-R-1 2000 Safety of nuclear power plants: Design - -
IAEA GS-R-3 2006 The management system for facilities and - -
activities : safety requirements
IAEA NS-G-1.3 2002 Instrumentation and control systems important to - -
safety in nuclear power plants
---------------------- Page: 7 ----------------------
SIST EN 61226:2010
---------------------- Page: 8 ----------------------
SIST EN 61226:2010
IEC 61226
Edition 3.0 2009-07
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Nuclear power plants – Instrumentation and control important to safety –
Classification of instrumentation and control functions
Centrales nucléaires de puissance – Instrumentation et contrôle-commande
importants pour la sûreté – Classement des fonctions d’instrumentation et de
contrôle-commande
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
PRICE CODE
INTERNATIONALE
CODE PRIX
ICS 27.120.20 ISBN 2-8318-1052-1
® Registered trademark of the International Electrotechnical Commission
Marque déposée de la Commission Electrotechnique Internationale
---------------------- Page: 9 ----------------------
SIST EN 61226:2010
– 2 – 61226 © IEC:2009
CONTENTS

FOREWORD...........................................................................................................................3

INTRODUCTION.....................................................................................................................5

1 Scope...............................................................................................................................8

2 Normative references .......................................................................................................8

3 Terms and definitions .......................................................................................................9

4 Abbreviations .................................................................................................................13

5 Classification scheme.....................................................................................................13

5.1 General .................................................................................................................13

5.2 Background ...........................................................................................................14

5.3 Description of categories.......................................................................................14

5.3.1 General .....................................................................................................14

5.3.2 Category A ................................................................................................15

5.3.3 Category B ................................................................................................15

5.3.4 Category C ................................................................................................15

5.4 Assignment criteria................................................................................................16

5.4.1 General .....................................................................................................16

5.4.2 Category A ................................................................................................16

5.4.3 Category B ................................................................................................16

5.4.4 Category C ................................................................................................17

6 Classification procedure .................................................................................................17

6.1 General .................................................................................................................17

6.2 Identification of design basis .................................................................................18

6.3 Identification and classification of functions...........................................................18

7 Assignment of technical requirements to categories .......................................................21

7.1 General requirements............................................................................................21

7.2 Requirements related to functions .........................................................................21

7.2.1 Basic requirements....................................................................................21

7.2.2 Specific requirements ................................................................................22

7.3 Requirements related to I&C systems....................................................................22

7.3.1 Basic requirements....................................................................................22

7.3.2 Specific requirements ................................................................................23

7.4 Requirements related to equipment .......................................................................25

7.4.1 Basic requirements....................................................................................25

7.4.2 Specific requirements ................................................................................25

7.5 Requirements related to quality aspects ................................................................26

7.5.1 Basic requirements....................................................................................26

7.5.2 Specific requirements ................................................................................26

Annex A (informative) Examples of categories .....................................................................30

Bibliography..........................................................................................................................32

Figure 1 – Method of classification........................................................................................20

Table 1 – Tabular correlation between categories and other IEC standards ..........................29

---------------------- Page: 10 ----------------------
SIST EN 61226:2010
61226 © IEC:2009 – 3 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
NUCLEAR POWER PLANTS –
INSTRUMENTATION AND CONTROL IMPORTANT TO SAFETY –
CLASSIFICATION OF INSTRUMENTATION AND CONTROL FUNCTIONS
FOREWORD

1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising

all national electrotechnical committees (IEC National Committees). The object of IEC is to promote

international co-operation on all questions concerning standardization in the electrical and electronic fields. To

this end and in addition to other activities, IEC publishes International Standards, Technical Specifications,

Technical Reports, Publicly Available Specifications (PAS) and Guides (hereafter referred to as “IEC

Publication(s)”). Their preparation is entrusted to technical committees; any IEC National Committee interested

in the subject dealt with may participate in this preparatory work. International, governmental and non-

governmental organizations liaising with the IEC also participate in this preparation. IEC collaborates closely

with the International Organization for Standardization (ISO) in accordance with conditions determined by

agreement between the two organizations.

2) The formal decisions or agreements of IEC on technical matters express, as nearly as possible, an international

consensus of opinion on the relevant subjects since each technical committee has representation from all

interested IEC National Committees.

3) IEC Publications have the form of recommendations for international use and are accepted by IEC National

Committees in that sense. While all reasonable efforts are made to ensure that the technical content of IEC

Publications is accurate, IEC cannot be held responsible for the way in which they are used or for any

misinterpretation by any end user.

4) In order to promote international uniformity, IEC National Committees undertake to apply IEC Publications

transparently to the maximum extent possible in their national and regional publications. Any divergence

between any IEC Publication and the corresponding national or regional publication shall be clearly indicated in

the latter.

5) IEC provides no marking procedure to indicate its approval and cannot be rendered responsible for any

equipment declared to be in conformity with an IEC Publication.

6) All users should ensure that they have the latest edition of this publication.

7) No liability shall attach to IEC or its directors, employees, servants or agents including individual experts and

members of its technical committees and IEC National Committees for any personal injury, property damage or

other damage of any nature whatsoever, whether direct or indirect, or for costs (including legal fees) and

expenses arising out of the publication, use of, or reliance upon, this IEC Publication or any other IEC

Publications.

8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is

indispensable for the correct application of this publication.

9) Attention is drawn to the possibility that some of the elements of this IEC Publication may be the subject of

patent rights. IEC shall not be held responsible for identifying any or all such patent rights.

International Standard IEC 61226 has been prepared by subcommittee 45A: Instrumentation

and control of nuclear facilities, of IEC technical committee 45: Nuclear instrumentation.

This third edition cancels and replaces the second edition published in 2005 and constitutes a

technical revision. The main changes with respect to the previous edition are listed below:

• to introduce a definition for “non-hazardous stable state”;
• to clarify limits of categories;
• to clarify requirements related to equipment used for beyond design events.
---------------------- Page: 11 ----------------------
SIST EN 61226:2010
– 4 – 61226 © IEC:2009
The text of this standard is based on the following documents:
FDIS Report on voting
45A/745/FDIS 45A/767/RVD

Full information on the voting for the approval of this standard can be found in the report on

voting indicated in the above table.

This publication has been drafted in accordance with the ISO/IEC Directives, Part 2.

The committee has decided that the contents of this publication will remain unchanged until

the maintenance result date indicated on the IEC web site under "http://webstore.iec.ch" in

the data related to the specific publication. At this date, the publication will be

• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.
---------------------- Page: 12 ----------------------
SIST EN 61226:2010
61226 © IEC:2009 – 5 –
INTRODUCTION
a) Technical background, main issues and organisation of the standard

This International Standard responds to an International Atomic Energy Agency (IAEA)

requirement to classify nuclear power plants instrumentation and control systems according

to their importance to safety. With distributed computer based I&C systems now being used

for NPP instrumentation and control systems, the functions important to safety are distributed

over several systems or subsystems. Therefore, it is the intent of this standard to

– classify the I&C functions important to safety into categories, depending on their

contribution to the prevention and mitigation of postulated initiating events (PIE), and to

develop requirements that are consistent with the importance to safety of each of the

categories;

– assign specification and design requirements to I&C systems and equipment concerned

which perform the classified functions.

According to IAEA recommendation, the methods of classification are primarily based on the

deterministic safety analysis, and should be complemented where appropriate by probabilistic

methods. Several possible approaches for use of probabilistic safety assessment (PSA) for

classification are described in IEC/TR 61838, “Nuclear power plants – Instrumentation and

control important to safety – Use of probabilistic safety assessment for the classification of

functions”.

This revision of the standard enables quantitative assessment to be partly taken into account.

b) Situation of the current standard in the structure of the SC 45A standard series

IEC 61226 is directly referenced by IEC 61513 and is the second level SC 45A document

tackling the issue of categorization of functions and classification of systems.

For more details on the structure of the SC 45A standard series see item d) of this

introduction.
c) Recommendation and limitation regarding the application of this standard

Correct classification of functions directs the appropriate degree of attention by the plant's

designers, operators and regulatory authorities to the specification, design, qualification,

quality assurance (QA), manufacturing, installation, maintenance, and testing of the systems

that ensure the safety functions.
—————————
IAEA NS-R-1 requirement 5.1.

The NS-R-1, section 5.2 requires that the method for classifying the safety significance of a structure, system

or component shall be primarily based on deterministic methods complemented where appropriate by

probabilistic methods and sound engineering judgment taking into account factors such as

a) the safety function(s) to be performed;
b) the consequences of failure to perform the function;

c) the probability that it (the I&C system) will be required to perform a safety function;

d) the time following a PIE at which, or the period throughout which it (the I&C system) will be called upon to

operate.
---------------------- Page: 13 ----------------------
SIST EN 61226:2010
– 6 – 61226 © IEC:2009

This standard establishes the criteria and methods to be used to assign the I&C functions of a

NPP to three categories A, B and C, which depend on the importance of the function for

safety, and an unclassified category for functions with no direct safety role. It outlines generic

requirements for each category, and specifies basic technical requirements for matters such

as QA, reliability, testing and maintenance.

The category to which a function is assigned determines generic and specific technical

requirements. Generic requirements for each function are based on providing the appropriate

level of assurance that it will be executed on demand with the required performance and

reliability level. This applies to the aspects of functionality, reliability, performance,

environmental durability and QA. The level of assurance to be shown for each of these

aspects must be consistent with the importance of the function to safety.

i) Assurance of functionality is established by the creation of a complete and comprehensive

requirements specification, and the application of appropriate standards and codes.

ii) Assurance of reliability is provided by the selection of appropriate components, structures

and levels of redundancy and diversity in association with physical separation and/or

barriers, electrical isolation and periodic testing during service.

iii) Assurance of performance is gained by the creation of specifications of the required

performance, the application of QA procedures, verification and validation processes

during design and manufacture, pre-service testing of the individual and integrated

systems and equipment, and testing during service.

iv) Assurance of environmental durability is established by equipment qualification

programmes to ensure that ageing effects and environmental conditions that exist when

the equipment is required to operate do not degrade its performance below that required.

v) Assurance that the aspects of functionality, performance, environmental durability and

reliability have been properly considered at each stage from conception, through design,

manufacture, test, installation, commissioning and entry into service is provided by

carrying out each stage of the work under the control of an appropriate QA program.

Throughout this standard, the auxiliary "shall" indicates requirements that are mandatory for

compliance with the standard, the auxiliary "should" indicates requirements that are not

mandatory for compliance with the standard but are strongly recommended and the auxiliary

"may" indicates requirements that are optional.

d) Description of the structure of the SC 45A standard series and relationships with

other IEC documents and other bodies documents (IAEA, ISO)

The top-level document of the IEC SC 45A standard series is IEC 61513. It provides general

requirements for I&C systems and equipment that are used to perform functions important to

safety in NPPs. IEC 61513 structures the IEC SC 45A standard series.

IEC 61513 refers directly to other IEC SC 45A standards for general topics related to

categorization of functions and classification of systems, qualification, separation of systems,

defence against common cause failure, software aspects of computer-based systems,

hardware aspects of computer-based systems, and control room design. The standards

referenced directly at this second level should be considered together with IEC 61513 as a

consistent document set.

At a third level, IEC SC 45A standards not directly referenced by IEC 61513 are standards

related to specific equipment, technical methods, or specific activities. Usually these

documents, which make reference to second-level documents for general topics, can be used

on their own.

A fourth level extending the IEC SC 45A standard series, corresponds to the technical reports

which are not normative.
---------------------- Page: 14 ----------------------
SIST EN 61226:2010
61226 © IEC:2009 – 7 –

IEC 61513 has adopted a presentation format similar to the basic safety publications of

IEC 61508 series with an overall safety life-cycle framework and a system life-cycle

framework and provides an interpretation of the general requirements of IEC 61508-1,

IEC 61508-2 and IEC 61508-4, for the nuclear application sector. Compliance with IEC 61513

will facilitate consistency with the requirements of IEC 61508 as they have been interpreted

for the nuclear industry. In this framework, IEC 60880 and IEC 62138 correspond to

IEC 61508-3 for the nuclear application sector.

IEC 61513 refers to ISO, as well as to IAEA 50-C-QA (now replaced by IAEA GS-R-3) for

topics related to quality assurance (QA).

The IEC SC 45A standards series consistently implements and details the principles and

basic safety aspects provided in the IAEA code on the safety of NPPs and in the IAEA safety

series, in particular the requirements NS-R-1, establishing safety requirements related to the

design of nuclear power plants, and the safety guide NS-G-1.3 dealing with instrumentation

and control systems important to safety in nuclear power plants. The terms and definitions

used by SC 45A standards are consistent with those used by the IAEA.
---------------------- Page: 15 ----------------------
SIST EN 61226:2010
– 8 – 61226 © IEC:2009
NUCLEAR POWER PLANTS –
INSTRUMENTATION AND CONTROL IMPORTANT TO SAFETY –
CLASSIFICATION OF INSTRUMENTATION AND CONTROL FUNCTIONS
1 Scope

This International Standard establishes a method of classification of the information and

command functions for nuclear power plants, and the I&C systems and equipment that

provide those functions, into categories that designate the importance to safety of the

function. The resulting classification then determines relevant design criteria.

The design criteria are the measures of quality by which the adequacy of each function in

relation to its importance to plant safety is ensured. In this standard, the criteria are those of

functionality, reliability, performance, environmental durability (including seismic) and quality

assurance (QA).

This standard is applicable to all the information and command functions and the instrument-

ation and control (I&C) systems and equipment that provide those functions. The functions,

systems and equipment under consideration provide automated protection, closed or open

loop control and information to the operating staff. They keep the NPP conditions inside the

safe operating envelope and provide automatic actions, or enable manual actions, that

prevent or mitigate accidents, or that prevent or minimize radioactive releases to the site or

wider environment. The I&C functions that fulfil these roles safeguard the health and safety of

the NPP operators and the public.

This standard follows the general principles given in IAEA safety code NS-R-1 and safety

guide NS-G-1.3, and it defines a structured method of applying the guidance contained in

those codes and standards to the I&C systems that perform functions important to safety in a

NPP. This standard should be read in association with the IAEA guides and IEC 61513 in

implementing the requirements of IEC 61508 series.
2 Normative references

The following referenced documents are indispensable for the application of this document.

For dated references, only the edition cited applies. For undated references, the latest edition

of the referenced document (including any amendments) applies.

IEC 60671:2007, Nuclear power plants – Instrumentation and control systems important to

safety – Surveillance testing

IEC 60709, Nuclear power plants – Instrumentation and control systems important to safety –

Separation

IEC 60780, Nuclear power plants – Electrical equipment of the safety system – Qualification

IEC 60812, Analysis techniques for system reliability – Procedure for failure mode and effects

analysi
...

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