BS EN IEC 62855:2021

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Nuclear power plants. Electrical power systems. Electrical power systems analysis

Published By	Publication Date	Number of Pages
BSI	2021	62

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Categories: 27.120.20 - Nuclear power plants. Safety, BSI

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Description

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.

PDF Catalog

PDF Pages	PDF Title
2	undefined
5	English CONTENTS
8	FOREWORD
10	INTRODUCTION
13	1 Scope
14	2 Normative references 3 Terms and definitions
15	4 Symbols and abbreviations
16	5 Electrical power system analyses 5.1 Overview of typical studies 5.1.1 Transient stability analyses 5.1.2 Load flow studies 5.1.3 Transient and dynamic studies
17	5.1.4 Short circuit studies 5.1.5 Electrical protection coordination and selectivity 5.1.6 Lightning protection studies 5.2 Applicability of analyses to different plant states 5.2.1 General 5.2.2 Recommendations
18	5.3 Selection, verification and validation of analytical tools 5.3.1 General
19	5.3.2 Recommendations
20	5.4 Electrical power system model 5.5 Grid and NPP connection 5.6 Updating of system analyses 5.7 Prerequisites for the performance of electrical studies
21	5.8 Acceptance requirements 6 Off-site power transient stability analyses 6.1 General 6.2 Recommendation 6.3 Acceptance requirements 7 AC on-site power system analyses 7.1 General
22	7.2 Load flow studies 7.2.1 General 7.2.2 Recommendations 7.2.3 Acceptance requirements 7.3 Transient studies 7.3.1 General 7.3.2 Faulted conditions
23	7.3.3 Bus transfer studies
24	7.3.4 Motor starting and reacceleration studies
25	7.3.5 House load operation 7.3.6 Voltage disturbances
26	7.3.7 Voltage surge caused by switching and malfunctions 7.3.8 Load sequencer studies
27	7.3.9 Frequency studies 7.4 Fault studies 7.4.1 Short-circuit studies
28	7.4.2 Earth fault (degraded insulation) studies 7.5 Electrical protection coordination studies 7.5.1 Recommendations
29	7.5.2 Acceptance requirements 8 DC system and uninterruptible AC system analyses 8.1 Load flow studies 8.1.1 General 8.1.2 Recommendations
30	8.1.3 Acceptance requirements 8.2 Transient studies 8.2.1 Rectifier 8.2.2 Inverter/UPS and bypass switch
31	8.3 Fault studies 8.3.1 Short circuit studies 8.3.2 Earth fault (degraded insulation) studies 8.4 Electrical protection coordination studies 8.4.1 Recommendations
32	8.4.2 Acceptance requirements 9 Miscellaneous analyses 9.1 Lightning protection studies 9.1.1 General 9.1.2 Recommendation
33	9.1.3 Acceptance requirements 9.2 Electromagnetic compatibility 9.2.1 General 9.2.2 Recommendation 9.3 Harmonic studies 9.3.1 General 9.3.2 Recommendation 9.4 Geomagnetic induced current (GIC) 9.5 Ferroresonance studies
34	Annex A (informative)Establishment of design bases for nuclear power plant electrical power systems A.1 Overview
35	Figures Figure A.1 – Input and process to determine the specific electrical design bases for a nuclear power plant and verification analyses
36	Figure A.2 – Relationship of the plant electrical power system, the off-site electrical power system and the on-site electrical power system for a nuclear power plant
37	A.2 Site electrical characteristics A.2.1 General Figure A.3 – Relationship of power supplies important to safety, safety power supplies, and the preferred power supply for a nuclear power plant
38	A.2.2 Grid disturbances A.2.3 Short circuit power
39	A.2.4 Lightning protection and insulation coordination A.2.5 Earthing characteristics
40	A.3 Plant electrical characteristics A.3.1 General A.3.2 Main generator characteristics A.3.3 Standby AC power sources and alternate AC source
42	A.3.4 DC power sources A.4 Conceptual electrical design criteria A.4.1 General A.4.2 Capacity of power sources A.4.3 Protection coordination
43	A.4.4 Voltage transients and interruptions A.4.5 Capability for bus transfer A.4.6 Capability for motor start and reacceleration A.4.7 System earthing
44	A.4.8 Capability of electrical equipment A.4.9 Electromagnetic interference A.4.10 Geomagnetic induced currents A.4.11 Ferroresonance
45	A.5 Conceptual nuclear design criteria A.5.1 General A.5.2 Reliability and availability, single failure criterion
46	A.5.3 Common cause failures (CCF) and common mode failures (CMF) A.6 Design bases analysis A.6.1 General
47	A.6.2 Voltage Figure A.4 – Typical voltage design bases
48	A.6.3 Sizing of safety standby AC power sources
49	A.6.4 Frequency A.6.5 Electrical consumers’ databases and power balances
51	Annex B (informative)Guidelines for analytical studies B.1 Analytical studies methodology B.1.1 General B.1.2 Process Figure B.1 – Overview of analytical studies
52	Figure B.2 – Phenomena
53	B.2 Example of detailed level B.2.1 Purpose B.2.2 Analysis and basics
54	B.2.3 Minimum required data B.2.4 Contribution of the study
55	Annex C (informative)Verification of design bases and equipment specification Tables Table C.1 – AC on-site power system analyses
56	Table C.2 – DC system and uninterruptible AC system analyses
58	Annex D (informative)Example of plant specific acceptance criteria
59	Bibliography

Additional information

Status	Definitive
Pages	62
Publication Date	2021-08-03
ISBN	978 0 539 17355 0
Standard Number	BS EN IEC 62855:2021
Title	Nuclear power plants. Electrical power systems. Electrical power systems analysis
Identical National Standard Of	EN IEC 62855:2021, IEC 62855:2016
Corrects	BS IEC 62855:2016
Descriptors	Nuclear-electric power stations, Nuclear fuels, Nuclear technology, Nuclear power, Nuclear physics, Energy sources
Publisher	BSI
Committee	NCE/8
ICS Codes	27.120.20 - Nuclear power plants. Safety

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