EN IEC 62855:2021

Nuclear power plants - Electrical power systems - Electrical power systems analysis

IEC 62855 provides the electrotechnical engineering guidelines for analysis of AC and DC electrical power systems in nuclear power plants (NPPs) in order to demonstrate that the power sources and the distribution systems have the capability for safe operation and shut down of the NPP, bringing it to a controlled state after an anticipated operational occurrence or accident conditions and finally reaching a safe state. The analytical studies discussed in this document provide assurance that the design bases are satisfied to meet their functional requirements under the conditions produced by the applicable design basis events. The studies provide assurance that the electrical power system is capable of supporting safety functions during all required plant conditions. NOTE The safety functions are described in IAEA Specific Safety Requirements SSR-2/1 related to the design of the nuclear power plants.. Analytical studies validate the robustness and adequacy of design margins and demonstrate the capability of electrical power systems to support plant operation for normal, abnormal, degraded and accident conditions. The analyses are used to verify that the electrical power system can withstand minor disturbances and that the consequences of major disturbances or failures do not degrade the capability of the electrical power systems to support safe shutdown of the plant and maintain the plant in shutdown condition. The analyses are performed with one or more of • simulation tools (software and hardware) that have been verified and validated, • hand calculations, and • tests. This document provides guidance on the types of analyses required to demonstrate that the plant's auxiliary power system can perform the required safety functions. This document does not provide specific details on how the analysis should be conducted. This document does not cover digital controllers (such as controllers for rectifiers, inverters, sequencers and electrical protection devices) used in electrical power systems. IEC 61513 gives recommendations that apply to the electronic controls and protective elements of the electrical power systems. This document does not include environmental conditions (i.e. temperature, humidity, etc.) or external events (seismic, flooding, fire, high energy electromagnetic pulse, etc.) that may impact equipment sizing or protection requirements. The external events lightning and geomagnetic storms are included. This document does not cover additional or unique requirements for stand-alone power system, such as power supplies for security measures in NPPs. Pertinent clauses of this document may be used as a guideline for such systems. Redundancy in the power system design can increase the availability of electrical power to critical plant equipment. Performing a probabilistic risk assessment (PRA) is a method of assessing system availability and optimizing design for high reliability. This document does not cover improving the reliability of NPP electrical power systems using statistical or diverse and redundant schemes. Requirements for safeguards of personnel involved with installation, maintenance and operation of electrical systems and general personal safety are outside the scope of this document. General guidance for lightning protection of equipment is provided in relevant clauses of this document. This document is intended to be used: • for verification of the design of new nuclear power plants, • for demonstrating the adequacy and impact of major modifications of electrical power systems in operating nuclear power plants, and • where there is a requirement to assess and establish operating limits and constraints for existing plants. Pertinent parts of this document can be used as guidance for decommissioning stages.

Kernkraftwerke - Elektrische Energieversorgungssysteme - Analyse der elektrischen Energieversorgungssysteme

Centrales nucléaires de puissance – Systèmes d’alimentation électrique – Analyse des systèmes d’alimentation électrique

L'IEC 62855:2016 donne les directives en matière d'ingénierie électrotechnique pour l'analyse des systèmes électriques de puissance en courant alternatif (CA) et en courant continu (CC) des centrales nucléaires (CNPE). Il s'agit de démontrer que les sources de puissance et le système de distribution électrique peuvent garantir le fonctionnement et l'arrêt sûr de la centrale, de manière à atteindre un état contrôlé après un incident de fonctionnement prévu, puis un état sûr. La présente norme a pour objectif d'être utilisée: - pour vérifier la conception des nouvelles centrales nucléaires de puissance; - pour démontrer la pertinence et l'impact de modifications majeures apportées aux systèmes électriques des CNPE en exploitation; - lorsque les centrales existantes font l'objet d'une exigence d'évaluation et d'établissement des limites ainsi que des contraintes de fonctionnement.

Jedrske elektrarne - Elektroenergetski sistemi - Analiza elektroenergetskih sistemov (IEC 62855:2016)

General Information

• Status: Published
• Publication Date: 15-Jul-2021
• ICS: 27.120.20 - Nuclear power plants. Safety
• Technical Committee: CLC/TC 45AX - Nuclear power plants
• Drafting Committee: CLC/TC 45AX - Nuclear power plants
• Current Stage: 6060 - Document made available - Publishing
• Start Date: 16-Jul-2021
• Completion Date: 16-Jul-2021
• Ref Project: SIST EN IEC 62855:2021 - Nuclear power plants - Electrical power systems - Electrical power systems analysis (IEC 62855:2016)

Standards Content (Sample)

SLOVENSKI STANDARD
01-september-2021
Jedrske elektrarne - Elektroenergetski sistemi - Analiza elektroenergetskih
sistemov (IEC 62855:2016)
Nuclear power plants - Electrical power systems - Electrical power systems analysis (IEC
62855:2016)
Kernkraftwerke - Elektrische Stromversorgung - Analyse der Stromversorgung (IEC
62855:2016)
Centrales nucléaires de puissance - Systèmes d’alimentation électrique - Analyse des
systèmes d’alimentation électrique (IEC 62855:2016)
Ta slovenski standard je istoveten z: EN IEC 62855:2021
ICS:
27.120.20 Jedrske elektrarne. Varnost Nuclear power plants. Safety
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EUROPEAN STANDARD EN IEC 62855

NORME EUROPÉENNE
EUROPÄISCHE NORM
July 2021
ICS 27.120.20
English Version
Nuclear power plants - Electrical power systems - Electrical
power systems analysis
(IEC 62855:2016)
Centrales nucléaires de puissance - Systèmes Kernkraftwerke - Elektrische Stromversorgung - Analyse
d'alimentation électrique - Analyse des systèmes der Stromversorgung
d'alimentation électrique (IEC 62855:2016)
(IEC 62855:2016)
This European Standard was approved by CENELEC on 2021-07-05. 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 CEN-CENELEC
Management Centre 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 CEN-CENELEC Management Centre 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, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland,
Turkey and the United Kingdom.

European Committee for Electrotechnical Standardization
Comité Européen de Normalisation Electrotechnique
Europäisches Komitee für Elektrotechnische Normung
CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2021 CENELEC All rights of exploitation in any form and by any means reserved worldwide for CENELEC Members.
Ref. No. EN IEC 62855:2021 E
European foreword
This document (EN IEC 62855:2021) consists of the text of IEC 62855:2016 prepared by IEC/TC 45
"Nuclear instrumentation".
The following dates are fixed:
• latest date by which the document has to be implemented at national (dop) 2022-07-05
level by publication of an identical national standard or by endorsement
• latest date by which the national standards conflicting with the (dow) 2024-07-05
document have to be withdrawn
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CENELEC shall not be held responsible for identifying any or all such patent rights.
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 and/or security measures in the subject-matter covered by this standard.
Any feedback and questions on this document should be directed to the users’ national standards
body/national committee. A complete listing of these bodies can be found on the CEN and CENELEC
websites.
Endorsement notice
The text of the International Standard IEC 62855:2016 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 60038 NOTE Harmonized as EN 60038
IEC 60364-5-52 NOTE Harmonized as HD 60364-5-52
IEC 60880 NOTE Harmonized as EN 60880
IEC 60964 NOTE Harmonized as EN IEC 60964
IEC 61225 NOTE Harmonized as EN IEC 61225
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
IEC 61513 NOTE Harmonized as EN 61513
IEC 62003 NOTE Harmonized as EN IEC 62003
IEC 62138 NOTE Harmonized as EN IEC 62138
IEC 62271-200 NOTE Harmonized as EN 62271-200
IEC 62305-1 NOTE Harmonized as EN 62305-1
IEC 62305-3 NOTE Harmonized as EN 62305-3
IEC 62305-4 NOTE Harmonized as EN 62305-4
IEC 62340 NOTE Harmonized as EN 62340
IEC 62566 NOTE Harmonized as EN 62566
IEC 62645 NOTE Harmonized as EN IEC 62645
IEC 63046 NOTE Harmonized as EN IEC 63046
ISO/IEC 27001 NOTE Harmonized as EN ISO/IEC 27001
ISO/IEC 27002 NOTE Harmonized as EN ISO/IEC 27002

IEC 62855 ®
Edition 1.0 2016-08
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
Nuclear power plants – Electrical power systems – Electrical power systems

analysis
Centrales nucléaires de puissance – Systèmes d’alimentation électrique –

Analyse des systèmes d’alimentation électrique

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 27.120.20 ISBN 978-2-8322-3589-8

– 2 – IEC 62855:2016  IEC 2016
CONTENTS
FOREWORD . 5
INTRODUCTION . 7
1 Scope . 10
2 Normative references. 11
3 Terms and definitions . 11
4 Symbols and abbreviations . 12
5 Electrical power system analyses . 13
5.1 Overview of typical studies . 13
5.1.1 Transient stability analyses . 13
5.1.2 Load flow studies . 13
5.1.3 Transient and dynamic studies . 13
5.1.4 Short circuit studies . 14
5.1.5 Electrical protection coordination and selectivity . 14
5.1.6 Lightning protection studies . 14
5.2 Applicability of analyses to different plant states . 14
5.2.1 General . 14
5.2.2 Recommendations . 14
5.3 Selection, verification and validation of analytical tools . 15
5.3.1 General . 15
5.3.2 Recommendations . 16
5.4 Electrical power system model . 17
5.5 Grid and NPP connection . 17
5.6 Updating of system analyses . 17
5.7 Prerequisites for the performance of electrical studies . 17
5.8 Acceptance requirements . 18
6 Off-site power transient stability analyses . 18
6.1 General . 18
6.2 Recommendation . 18
6.3 Acceptance requirements . 18
7 AC on-site power system analyses . 18
7.1 General . 18
7.2 Load flow studies . 19
7.2.1 General . 19
7.2.2 Recommendations . 19
7.2.3 Acceptance requirements . 19
7.3 Transient studies . 19
7.3.1 General . 19
7.3.2 Faulted conditions . 19
7.3.3 Bus transfer studies . 20
7.3.4 Motor starting and reacceleration studies . 21
7.3.5 House load operation . 22
7.3.6 Voltage disturbances . 22
7.3.7 Voltage surge caused by switching and malfunctions . 23
7.3.8 Load sequencer studies . 23
7.3.9 Frequency studies . 24
7.4 Fault studies . 24

IEC 62855:2016  IEC 2016 – 3 –
7.4.1 Short-circuit studies . 24
7.4.2 Earth fault (degraded insulation) studies . 25
7.5 Electrical protection coordination studies . 25
7.5.1 Recommendations . 25
7.5.2 Acceptance requirements . 26
8 DC system and uninterruptible AC system analyses . 26
8.1 Load flow studies . 26
8.1.1 General . 26
8.1.2 Recommendations . 26
8.1.3 Acceptance requirements . 27
8.2 Transient studies . 27
8.2.1 Rectifier . 27
8.2.2 Inverter/UPS and bypass switch . 27
8.3 Fault studies . 28
8.3.1 Short circuit studies . 28
8.3.2 Earth fault (degraded insulation) studies . 28
8.4 Electrical protection coordination studies . 28
8.4.1 Recommendations . 28
8.4.2 Acceptance requirements . 29
9 Miscellaneous analyses . 29
9.1 Lightning protection studies . 29
9.1.1 General . 29
9.1.2 Recommendation . 29
9.1.3 Acceptance requirements .
...