IEC 62138:2018

Nuclear power plants - Instrumentation and control systems important to safety - Software aspects for computer-based systems performing category B or C functions

IEC 62138:2018 is also available as IEC 62138:2018 RLV which contains the International Standard and its Redline version, showing all changes of the technical content compared to the previous edition.
IEC 62138:2018 specifies requirements for the software of computer-based instrumentation and control (I&C) systems performing functions of safety category B or C as defined by IEC 61226. It complements IEC 60880 which provides requirements for the software of computer-based I&C systems performing functions of safety category A. It is consistent with, and complementary to, IEC 61513. Requirements that are not specific to software are deferred to IEC 61513. This new edition includes the following significant technical changes with respect to the previous edition:
- align the standard with standards published or revised since the first edition, in particular IEC 61513, IEC 60880, IEC 62645 and IEC 62671;
- merge two clauses in order to avoid repetitions of text;
- introduce requirements on traceability in consistency with IEC 61513;
- introduce new annexes.

Centrales nucléaires de puissance - Systèmes d'instrumentation et de contrôle-commande importants pour la sûreté - Aspects logiciels des systèmes informatisés réalisant des fonctions de catégorie B ou C

IEC 62138:2018 est disponible sous forme de IEC 62138:2018 RLV qui contient la Norme internationale et sa version Redline, illustrant les modifications du contenu technique depuis l'édition précédente.
L'IEC 62138:2018 spécifie des exigences sur les logiciels des systèmes d’instrumentation et de contrôle-commande (I&C) informatisés réalisant des fonctions de sûreté de catégorie B ou C, selon la définition donnée par l’IEC 61226. Il est complémentaire à l’IEC 60880 qui énonce des exigences sur le logiciel des systèmes d’I&C informatisés réalisant des fonctions de sûreté de catégorie A. Il est également cohérent et complémentaire à l’IEC 61513. Les exigences qui ne sont pas spécifiques au logiciel sont reportées dans l’IEC 61513. Cette nouvelle édition inclut les modifications techniques majeures suivantes par rapport à l'édition précédente:
- aligner la présente norme sur les normes publiées ou révisées depuis sa première édition, en particulier l'IEC 61513, l'IEC 60880, l'IEC 62645, l'IEC 62671;
- fusionner deux articles pour éviter des répétitions de texte;
- introduire des exigences portant sur la traçabilité en cohérence avec l’IEC 61513;
- introduire de nouvelles annexes.

General Information

• Status: Published
• Publication Date: 30-Jul-2018
• ICS: 01 - GENERALITIES. TERMINOLOGY. STANDARDIZATION. DOCUMENTATION
• ICS: 27.120.20 - Nuclear power plants. Safety
• Technical Committee: SC 45A - Instrumentation, control and electrical power systems of nuclear facilities
• Drafting Committee: WG 3 - TC 45/SC 45A/WG 3
• Current Stage: PPUB - Publication issued
• Start Date: 13-Jul-2018
• Completion Date: 31-Jul-2018

Relations

• Revises: IEC 62138:2004 - Nuclear power plants - Instrumentation and control important for safety - Software aspects for computer-based systems performing category B or C functions
• Effective Date: 05-Sep-2023

Standards Content (Sample)

IEC 62138 ®
Edition 2.0 2018-07
REDLINE VERSION
INTERNATIONAL
STANDARD
colour
inside
Nuclear power plants – Instrumentation and control systems important for to
safety – Software aspects for computer-based systems performing category
B or C functions
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form
or by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from
either IEC or IEC's member National Committee in the country of the requester. If you have any questions about IEC
copyright or have an enquiry about obtaining additional rights to this publication, please contact the address below or
your local IEC member National Committee for further information.

IEC Central Office Tel.: [phone]
3, rue de Varembé [e-mail]
CH-1211 Geneva 20 www.iec.ch
Switzerland
About the IEC
The International Electrotechnical Commission (IEC) is the leading global organization that prepares and publishes
International Standards for all electrical, electronic and related technologies.

About IEC publications
The technical content of IEC publications is kept under constant review by the IEC. Please make sure that you have the
latest edition, a corrigenda or an amendment might have been published.

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IEC 62138 ®
Edition 2.0 2018-07
REDLINE VERSION
INTERNATIONAL
STANDARD
colour
inside
Nuclear power plants – Instrumentation and control systems important for to

safety – Software aspects for computer-based systems performing category

B or C functions
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 27.120.20 ISBN 978-2-8322-5927-6

– 2 – IEC 62138:2018 RLV © IEC 2018
CONTENTS
FOREWORD . 4
INTRODUCTION . 6
1 Scope . 9
2 Normative references. 10
3 Terms and definitions and abbreviations . 10
4 Symbols and abbreviated terms . 19
5 Key concepts and assumptions . 19
5.1 General . 19
5.2 Types of software . 19
5.3 Types of configuration data . 21
5.4 Software and system safety lifecycles . 21
5.5 Gradation principles . 24
Requirements for the software of I&C systems performing category C functions .
General requirements .
Selection of pre-developed software .
Software requirements specification .
Software design .
Implementation of new software .
Software aspects of system integration .
Software aspects of system validation .
Installation of software on site .
Anomaly reports .
Software modification .
6 Requirements for the software of class 2 and class 3 I&C systems performing
category B functions . 37
6.1 Applicability of the requirements . 37
6.2 General requirements . 37
6.2.1 Software safety lifecycle – Software quality assurance . 37
6.2.2 Verification . 38
6.2.3 Configuration management . 39
6.2.4 Selection and use of software tools . 40
6.2.5 Selection of languages . 41
Security .
6.3 Selection of pre-developed software . 43
6.3.1 General . 43
6.3.2 Documentation for safety. 43
6.3.3 Evidence of correctness . 44
6.3.4 Functional suitability . 51
Selection and use of dedicated devices with embedded software .
6.3.5 Selection and use of digital devices of limited functionality . 52
6.4 Software requirements specification . 52
6.4.1 General . 52
6.4.2 Objectives . 52
6.4.3 Inputs . 52
6.4.4 Contents . 53
6.4.5 Properties . 54

6.5 Software design . 54
6.5.1 Objectives . 54
6.5.2 Inputs . 55
6.5.3 Contents . 55
6.5.4 Properties . 56
6.6 Implementation of software . 57
6.6.1 General requirements . 57
6.6.2 Configuration of software and of devices containing software . 57
6.6.3 Implementation with application-oriented languages . 57
6.6.4 Implementation with general-purpose languages . 58
6.7 Software aspects of system integration . 60
6.7.1 General . 60
6.8 Software aspects of system validation . 60
6.8.1 General . 60
6.9 Installation of software on site . 62
6.9.1 General . 62
6.10 Anomaly reports . 62
6.11 Software modification . 63
6.11.1 General . 63
6.12 Defences against common cause failure due to software . 64
Annex A (informative) Typical list of software documentation . 66
Annex B (informative) Correspondence between IEC 61513:2011 and this document . 67
Annex C (informative) Relations of this document with IEC 61508 . 68
C.1 General . 68
C.2 Comparison of scope and concepts . 68
C.3 Correspondence between this document and IEC 61508-3:2010 . 69
Bibliography . 70

Figure – Process for providing evidence of correctness for pre-developed software of
an I&C system of safety class 2. .
Figure 1 – Typical software parts in a computer-based I&C system . 20
Figure 2 – Activities of the system safety lifecycle (as defined by IEC 61513:2011) . 21
Figure 3 – Software related activities in the system safety lifecycle . 22
Figure 4 – Development activities of the IEC 62138 software safety lifecycle . 23
Figure 5 – Overview of the typical qualification process for pre-developed complete
operational system software . 46
Figure 6 – Overview of the typical qualification process for pre-developed software

components . 47

Table A.1 – Typical list of software documentation . 66
Table B.1 – Correspondence between IEC 61513:2011 and this document . 67
Table C.1 – Correspondence between this document and IEC 61508-3:2010 . 69

– 4 – IEC 62138:2018 RLV © IEC 2018
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
NUCLEAR POWER PLANTS – INSTRUMENTATION
AND CONTROL SYSTEMS IMPORTANT FOR TO SAFETY –
SOFTWARE ASPECTS FOR COMPUTER-BASED SYSTEMS
PERFORMING CATEGORY B OR C 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
...

IEC 62138 ®
Edition 2.0 2018-07
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Nuclear power plants – Instrumentation and control systems important to
safety – Software aspects for computer-based systems performing category
B or C functions
Centrales nucléaires de puissance – Systèmes d’instrumentation et de contrôle-
commande importants pour la sûreté – Aspects logiciels des systèmes
informatisés réalisant des fonctions de catégorie B ou C

All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form
or by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from
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CH-1211 Geneva 20 www.iec.ch
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About the IEC
The International Electrotechnical Commission (IEC) is the leading global organization that prepares and publishes
International Standards for all electrical, electronic and related technologies.

About IEC publications
The technical content of IEC publications is kept under constant review by the IEC. Please make sure that you have the
latest edition, a corrigenda or an amendment might have been published.

IEC Catalogue - webstore.iec.ch/catalogue Electropedia - www.electropedia.org
The stand-alone application for consulting the entire The world's leading online dictionary of electronic and
bibliographical information on IEC International Standards, electrical terms containing 21 000 terms and definitions in
Technical Specifications, Technical Reports and other English and French, with equivalent terms in 16 additional
documents. Available for PC, Mac OS, Android Tablets and languages. Also known as the International Electrotechnical
iPad. Vocabulary (IEV) online.

IEC publications search - webstore.iec.ch/advsearchform IEC Glossary - std.iec.ch/glossary
The advanced search enables to find IEC publications by a 67 000 electrotechnical terminology entries in English and
variety of criteria (reference number, text, technical French extracted from the Terms and Definitions clause of
committee,…). It also gives information on projects, replaced IEC publications issued since 2002. Some entries have been
and withdrawn publications. collected from earlier publications of IEC TC 37, 77, 86 and

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IEC 62138 ®
Edition 2.0 2018-07
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Nuclear power plants – Instrumentation and control systems important to

safety – Software aspects for computer-based systems performing category

B or C functions
Centrales nucléaires de puissance – Systèmes d’instrumentation et de contrôle-

commande importants pour la sûreté – Aspects logiciels des systèmes

informatisés réalisant des fonctions de catégorie B ou C

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 27.120.20 ISBN 978-2-8322-5830-9

– 2 – IEC 62138:2018 © IEC 2018
CONTENTS
FOREWORD . 4
INTRODUCTION . 6
1 Scope . 8
2 Normative references. 8
3 Terms and definitions . 9
4 Symbols and abbreviated terms . 17
5 Key concepts and assumptions . 17
5.1 General . 17
5.2 Types of software . 17
5.3 Types of configuration data . 18
5.4 Software and system safety lifecycles . 19
5.5 Gradation principles . 21
6 Requirements for the software of class 2 and class 3 I&C systems . 22
6.1 Applicability of the requirements . 22
6.2 General requirements . 22
6.2.1 Software safety lifecycle – Software quality assurance . 22
6.2.2 Verification . 23
6.2.3 Configuration management . 24
6.2.4 Selection and use of software tools . 25
6.2.5 Selection of languages . 26
6.3 Selection of pre-developed software . 27
6.3.1 General . 27
6.3.2 Documentation for safety. 27
6.3.3 Evidence of correctness . 28
6.3.4 Functional suitability . 35
6.3.5 Selection and use of digital devices of limited functionality . 35
6.4 Software requirements specification . 35
6.4.1 General . 35
6.4.2 Objectives . 35
6.4.3 Inputs . 36
6.4.4 Contents . 36
6.4.5 Properties . 37
6.5 Software design . 38
6.5.1 Objectives . 38
6.5.2 Inputs . 38
6.5.3 Contents . 39
6.5.4 Properties . 40
6.6 Implementation of software . 40
6.6.1 General requirements . 40
6.6.2 Configuration of software and of devices containing software . 40
6.6.3 Implementation with application-oriented languages . 41
6.6.4 Implementation with general-purpose languages . 41
6.7 Software aspects of system integration . 43
6.7.1 General . 43
6.8 Software aspects of system validation . 43
6.8.1 General . 43

6.9 Installation of software on site . 45
6.9.1 General . 45
6.10 Anomaly reports . 45
6.11 Software modification . 46
6.11.1 General . 46
6.12 Defences against common cause failure due to software . 47
Annex A (informative) Typical list of software documentation . 48
Annex B (informative) Correspondence between IEC 61513:2011 and this document . 49
Annex C (informative) Relations of this document with IEC 61508 . 50
C.1 General . 50
C.2 Comparison of scope and concepts . 50
C.3 Correspondence between this document and IEC 61508-3:2010 . 51
Bibliography . 52

Figure 1 – Typical software parts in a computer-based I&C system . 18
Figure 2 – Activities of the system safety lifecycle (as defined by IEC 61513:2011) . 19
Figure 3 – Software related activities in the system safety lifecycle . 20
Figure 4 – Development activities of the IEC 62138 software safety lifecycle . 21
Figure 5 – Overview of the typical qualification process for pre-developed complete
operational system software . 30
Figure 6 – Overview of the typical qualification process for pre-developed software

components .
...