IEC 60772:2018

IEC 60772 ®
Edition 2.0 2018-05
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Nuclear power plants – Instrumentation systems important to safety – Electrical
penetration assemblies in containment structures

Centrales nucléaires de puissance – Systèmes d’instrumentation importants
pour la sûreté – Ensembles de traversée électrique dans les structures de
confinement
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IEC 60772 ®
Edition 2.0 2018-05
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Nuclear power plants – Instrumentation systems important to safety – Electrical

penetration assemblies in containment structures

Centrales nucléaires de puissance – Systèmes d’instrumentation importants

pour la sûreté – Ensembles de traversée électrique dans les structures de

confinement
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 27.120.20 ISBN 978-2-8322-5691-6

– 2 – IEC 60772:2018 © IEC 2018
CONTENTS
FOREWORD . 5
INTRODUCTION . 7
1 Scope . 10
2 Normative references . 11
3 Terms and definitions . 12
4 Abbreviated terms, symbols and acronyms . 16
5 EPA types and ratings . 16
5.1 EPA module type . 16
5.1.1 General . 16
5.1.2 Medium voltage power . 16
5.1.3 Low voltage power . 17
5.1.4 Low voltage control . 17
5.1.5 Instrumentation . 17
5.1.6 Fibre optic . 18
5.2 Ratings . 18
5.2.1 Rated operational voltage . 18
5.2.2 Rated operational current . 18
5.2.3 Rated overload current and durations . 19
5.2.4 Rated conditional short-circuit current . 19
5.2.5 Rated duration of short-circuit . 19
5.2.6 Rated signal transmission characteristics . 19
5.2.7 Rated capabilities during DBE and DEC . 20
6 Design requirements . 20
6.1 General . 20
6.2 Mechanical design requirements . 20
6.2.1 Pressure boundary . 20
6.2.2 Gas leakage . 20
6.2.3 Testing provisions . 21
6.2.4 Integrity and tightness . 21
6.2.5 Handling, transportation and storage . 21
6.2.6 Attachment (installation) . 21
6.2.7 Condensation . 21
6.2.8 Resistance against induced vibrations . 22
6.2.9 Pressure equalization, and protection against water and dust . 22
6.2.10 Decontamination capability . 22
6.2.11 Fire protection . 22
6.2.12 Stress analysis . 22
6.2.13 Accessibility. 22
6.2.14 Shielding against radiation . 22
6.2.15 Requirements for structural materials . 22
6.2.16 Requirements for EPA sealing design (materials and construction) . 23
6.3 Electrical design requirements . 23
6.3.1 Behaviour in the case of fire . 23
6.3.2 Partial discharge . 23
6.3.3 Connection Interfaces . 23
6.3.4 Electrical function . 24

6.3.5 Reassessing qualified life . 24
6.3.6 Electrodynamic stresses . 24
6.3.7 Conductor modules . 24
6.3.8 Instrumentation conductor modules . 24
6.3.9 Fibre optic conductor modules . 25
6.3.10 Electromagnetic interference . 25
6.3.11 Heating and current-carrying capability . 25
6.3.12 Electrical insulation design (materials and construction) . 25
7 Design qualification . 26
7.1 Selection of test specimens . 26
7.2 Qualification margins . 26
7.3 Design tests (materials and construction) . 26
7.3.1 Behaviour in the case of fire . 26
7.3.2 Radiation resistance . 26
7.3.3 Thermal endurance . 27
7.3.4 Ageing and qualified life . 27
7.3.5 Type tests . 27
7.4 Qualified life test . 31
7.4.1 General . 31
7.4.2 Initial tests . 32
7.4.3 Preconditioning . 32
7.4.4 Qualified life type tests . 33
7.5 Accident resistance tests . 33
7.5.1 Accident radiation . 33
7.5.2 Accident simulation test . 33
7.5.3 Acceptance tests . 34
7.6 Confirming the survivability in the case of DEC (e.g. severe accident) . 34
7.7 Reassessing the qualified life . 34
8 Production tests. 35
8.1 General . 35
8.2 Pneumatic pressure test . 35
8.3 Gas leak rate test . 35
8.4 Dielectric strength test . 35
8.4.1 Medium voltage power EPA . 35
8.4.2 Low voltage power EPA . 35
8.5 Insulation resistance test . 36
8.6 Conductor continuity test . 36
8.7 Signal transmission characteristics . 36
8.8 Fibre optic conductor modules . 36
8.9 Conductor identification . 36
9 Installation and field testing . 36
9.1 Installation procedure . 36
9.2 Mechanical installation . 36
9.3 Leak rate test . 37
9.4 Electrical tests . 37
9.5 Fibre optic conductor modules . 37
10 Quality assurance requirements . 37
10.1 Materials, processes and personnel . 37

– 4 – IEC 60772:2018 © IEC 2018
10.2 Documentation of design qualification . 37
10.3 Assembly and nameplate . 38
10.4 Data and ratings . 39
Annex A (informative) Conversion of leak rates of miscellaneous test gases . 40
A.1 General . 40
A.2 Conversion formulas . 40
Bibliography . 41

Table 1 – Defined leak rates by configuration . 20

INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
NUCLEAR POWER PLANTS – INSTRUMENTATION
SYSTEMS IMPORTANT TO SAFETY – ELECTRICAL
PENETRATION ASSEMBLIES IN CONTAINMENT STRUCTURES

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
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5) IEC itself does not provide any attestation of conformity. Independent certification bodies provide conformity
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6) All users should ensure that they have the latest edition of this publication.
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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 60772 has been prepared by subcommittee 45A: Instrumentation,
control and electrical power systems of nuclear facilities, of IEC technical committee 45:
Nuclear instrumentation.
This second edition cancels and replaces the first edition published in 1983. This edition
constitutes a technical revision.
This edition includes the following significant technical changes with respect to the previous
edition:
a) Adaptation of terminology and definitions to current available IAEA and IEC glossaries.
b) Inclusion of new requirements with respect to DBEs and DECs.
c) Inclusion of new requirements with respect to design, construction and material used for
electrical penetration assembly.
d) Inclusion of discussion of ageing models to be used for accelerated ageing due to
temperature and radiation.
– 6 – IEC 60772:2018 © IEC 2018
e) Inclusion of requirements in accordance with current standards on switchgears and
cables.
f) Inclusion of definitions of characteristics for instrumentation electrical penetration
assemblies.
g) More demand of electrical measurement during DBE and DEC.
The text of this International Standard is based on the following documents:
FDIS Report on voting
45A/1190/FDIS 45A/1203/RVD
Full information on the voting for the approval of this International Standard can be found in
the report on voting indicated in the above table.
This document has been drafted in accordance with the ISO/IEC Directives, Part 2.
The committee has decided that the contents of this document will remain unchanged until the
stability date indicated on the IEC website under "http://webstore.iec.ch" in the data related to
the specific document. At this date, the document will be
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.
INTRODUCTION
a) Technical background, main issues and organisation of the Standard
This International Standard focuses on electrical penetration assemblies (EPAs) in
containment structures. EPAs used in safety systems in nuclear facilities need to comply with
various Standards in order to meet their safety functional requirements throughout their
qualified life. This goal is accomplished by thorough designing, qualifying, manufacturing,
testing, installation and commissioning.
Therefore, this IEC standard specifically focuses on the above-mentioned aspects. Other
aspects, relating to quality assurance, reliability and selection including validation and
.
verification activities are not part of this standard
This second edition cancels and replaces the first edition published in 1983. The current
version of this standard is intended to accomplish the following:
• Respecting new technologies (e.g. fibre optic application for signal transfer in NPPs).
• Additional potential events/accidents scenarios are to be taken into consideration. For
instance, DEC scenarios are now considered in the design requirements and qualification
of electrical penetration assemblies.
• Adaptation to revised or new second level standards such as IEC 60980 or
IEC/IEEE 60780-323.
• Respecting the utilisation of digital electronic equipment in I&C systems instead of
relay-based devices requires that more detailed consideration shall be given to resistance
against electromagnetic disturbances,
• Inclusion of the comprehensive considerations of design and materials. Herein approaches
as stated in IEC 60216 series and IEC 60544 series are taken into account.
• Methods for the performance of on-going qualification/reassessing the qualified life as
requested in the newest revision of IEC/IEEE 60780-323 are taken into account.
This revision incorporates current practices and lessons learned from the implementation of
previous versions of this standard by the nuclear industry. As part of the pressure boundary of
the containment the electrical penetration assembly is always equipment important to safety,
which has to ensure the containment integrity. Also, the electrical function of the EPA has to
be ensured under DBE and DEC condition when it is part of an actuator or measurement
chain.
This Standard does not address the design, associated calculations and test conditions of the
mechanical aspects of penetration assemblies; these are published in other Standards such
as ASME and European Boiler and Vessel codes. Therefore, this Standard provides
references to other Standards as necessary.
b) Situation of the current Standard in the structure of the IEC SC 45A standard series
IEC 60772 is a third level IEC SC 45A document which addresses the design, qualification,
manufacturing, manufacturing testing, installation and commissioning of electrical penetration
assemblies.
For more details on the structure of the IEC SC 45A standard series, see item d) of this
introduction.
– 8 – IEC 60772:2018 © IEC 2018
c) Recommendations and limitations regarding the application of the Standard
IEC/IEEE 60780-323 and IEC 60980 are second level standards that give guidance for
specific aspects of functional qualification of electrical equipment important to safety; in
particular to environmental and seismic qualification. IEC 60772 is to be read in conjunction
with those two documents.
To ensure that the Standard will continue to be relevant in future years, the emphasis has
been placed on issues of principle, rather than specific technologies. Therefore, it is the task
of the manufacturer, architect engineer or operator to adapt this standard to the respective
needs.
d) Description of the structure of the IEC SC 45A standard series and relationships
with other IEC documents and other bodies documents (IAEA, ISO)
The top-level documents of the IEC SC 45A standard series are IEC 61513 and IEC 63046.
IEC 61513 provides general requirements for I&C systems and equipment that are used to
perform functions important to safety in NPPs. IEC 63046 provides general requirements for
electrical power systems of NPPs; it covers power supply systems including the supply
systems of the I&C systems. IEC 61513 and IEC 63046 are to be considered in conjunction
and at the same level. IEC 61513 and IEC 63046 structure the IEC SC 45A standard series
and shape a complete framework establishing general requirements for instrumentation,
control and electrical systems for nuclear power plants.
IEC 61513 and IEC 63046 refer directly to other IEC SC 45A standards for general topics
related to categorization of functions and classification of systems, qualification, separation,
defence against common cause failure, control room design, electromagnetic compatibility,
cybersecurity, software and hardware aspects for programmable digital systems, coordination
of safety and security requirements and management of ageing. The standards referenced
directly at this second level should be considered together with IEC 61513 and IEC 63046 as
a consistent document set.
At a third level, IEC SC 45A standards not directly referenced by IEC 61513 or by IEC 63046
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.
The IEC SC 45A standards series consistently implements and details the safety and security
principles and basic aspects provided in the relevant IAEA safety standards and in the
relevant documents of the IAEA nuclear security series (NSS). In particular this includes the
IAEA requirements SSR-2/1, establishing safety requirements related to the design of nuclear
power plants (NPPs), the IAEA safety guide SSG-30 dealing with the safety classification of
structures, systems and components in NPPs, the IAEA safety guide SSG-39 dealing with the
design of instrumentation and control systems for NPPs, the IAEA safety guide SSG-34
dealing with the design of electrical power systems for NPPs and the implementing guide
NSS17 for computer security at nuclear facilities. The safety and security terminology and
definitions used by SC 45A standards are consistent with those used by the IAEA.

IEC 61513 and IEC 63046 have adopted a presentation format similar to the basic safety
publication IEC 61508 with an overall life-cycle framework and a system life-cycle framework.
Regarding nuclear safety, IEC 61513 and IEC 63046 provide the interpretation of the general
requirements of IEC 61508-1, IEC 61508-2 and IEC 61508-4, for the nuclear application
sector. In this framework IEC 60880, IEC 62138 and IEC 62566 correspond to IEC 61508-3
for the nuclear application sector. IEC 61513 and IEC 63046 refer to ISO as well as to IAEA
GS-R-3 and IAEA GS-G-3.1 and IAEA GS-G-3.5 for topics related to quality assurance (QA).
At level 2, regarding nuclear security, IEC 62645 is the entry document for the IEC SC 45A
security standards. It builds upon the valid high level principles and main concepts of the
generic security standards, in particular ISO/IEC 27001 and ISO/IEC 27002; it adapts them
and completes them to fit the nuclear context and coordinates with the IEC 62443 series. At
level 2, IEC 60964 is the entry document for the IEC SC 45A control room standards and
IEC 62342 is the entry document for the IEC SC 45A ageing management standards.
NOTE 1 It is assumed that for the design of I&C systems in NPPs that implement conventional safety functions
(e.g. to address worker safety, asset protection, chemical hazards, process energy hazards) international or
national standards would be applied.
NOTE 2 IEC SC 45A domain was extended in 2013 to cover electrical systems. In 2014 and 2015 discussions
were held in IEC SC 45A to decide how and where general requirements for the design of electrical systems were
to be considered. IEC SC 45A experts recommended that an independent standard be developed at the same level
as IEC 61513 to establish general requirements for electrical systems. Project IEC 63046 is now launched to cover
this objective. When IEC 63046 is published, this NOTE 2 of the introduction of IEC SC 45A standards will be
suppressed.
– 10 – IEC 60772:2018 © IEC 2018
NUCLEAR POWER PLANTS – INSTRUMENTATION
SYSTEMS IMPORTANT TO SAFETY – ELECTRICAL
PENETRATION ASSEMBLIES IN CONTAINMENT STRUCTURES

1 Scope
This document applies to electrical penetration assemblies (EPAs) in containment structures
of nuclear power plants. It covers the engineering safety requirements to be met in the
design, calculation, qualification, fabrication, assembly, testing, and installation of EPAs.
EPAs provide gas-tight and pressure-resistant penetrations through the containment for one
or more electrical circuits. EPA requirements are divided into mechanical (e.g. containment
integrity), and electrical or optical aspects regarding safety. The mechanical requirements are
valid for all EPAs. The electrical or optical requirements are derived from the functional
requirements of the connected systems, applied for monitoring and mitigating postulated
events such as design basis events (DBE; e.g. loss of coolant accidents) and/or design
extension conditions (DEC; e.g. severe accidents).
EPAs are distinguished by the type of electrical or optical circuit in which they are used. The
derived types of EPAs are identified as follows:
• medium voltage power,
• low voltage power,
• control,
• instrumentation, and
• fibre optic.
For the purpose of this document, EPAs include:
• electrical conductors up to the connection interface inside and outside the containment
(penetration conductors);
• the electrical insulation systems of penetration conductors including the electrical
insulation of the connection interface;
• components for the resistance to environmental conditions, such as pressure resistance,
gas tightness, temperature resistance, radiations resistance, seismic resistance enclosure
of this EPA, and for connection with the containment wall;
• if required, permanently connected equipment for leak tightness monitoring;
• standard electrical connection interfaces such as cable lugs, terminals, and connectors;
• terminals and/or junction boxes (if necessary).
The components, which are not part of an EPA, include:
• components of the containment wall for the attachment of the EPA, such as sealing
surfaces for bolting, or pipe connections, or nozzles requiring welding;
• cables and wires connected to the EPA conductors or connectors;
• terminal elements such as cable lugs, terminals, connectors or soldering sleeves attached
to the cables and lines connected;
• leak test or evacuation devices connected temporarily to penetrations;
• the requirements for external circuits, connected to the EPA or the containment structure.
This document does not cover requirements for EPAs regarding operation and maintenance.

2 Normative references
The following documents are referred to in the text in such a way that some or all of their
content constitutes requirements 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 60038:2009, IEC standard voltages
IEC 60059:1999, IEC standard current ratings
IEC 60068-2-1, Environmental testing – Part 2-1: Tests – Test A: Cold
IEC 60068-2-2, Environmental testing – Part 2-2: Tests – Test B: Dry heat
IEC 60068-3-3, Environmental testing – Part 3-3: Guidance – Seismic test methods for
equipments
IEC 60137:2017, Insulated bushings for alternating voltages above 1 000 V
IEC 60216 (all parts), Electrical insulating materials – Thermal endurance properties
IEC 60332 (all parts), Tests on electric and optical fibre cables under fire conditions
IEC 60529:1989, Degrees of protection provided by enclosures (IP Code)
IEC 60544 (all parts), Electrical insulating materials – Determination of the effects of ionizing
radiation
IEC 60664-1:2007, Insulation coordination for equipment within low-voltage systems – Part 1:
principles, requirements and tests
IEC 60754-2:2011, Test on gases evolved during combustion of materials from cables –
Part 2: determination of acidity (by pH measurement) and conductivity
IEC/IEEE 60780-323:2016, Nuclear facilities – Electrical equipment important to safety –
Qualification
IEC 60947-1:2007, Low-voltage switchgear and controlgear – Part 1: General rules
IEC 60980, Recommended practices for seismic qualification of electrical equipment of the
safety system for nuclear power generating stations.
IEC 61034-2:2005, Measurement of smoke density of cables burning under defined conditions
– Part 2: test procedure and requirements
IEC 61156-1, Multicore and symmetrical pair/quad cables for digital communications – Part 1:
General specification
IEC 61196-1-113:2009, Coaxial communication cables – Part 1-113: Electrical test methods –
Test for attenuation constant
IEC 62271-1:2017, High-voltage switchgear and controlgear – Part 1: Common specifications
for alternating current switchgear and controlgear

– 12 – IEC 60772:2018 © IEC 2018
IEC 62271-200:2011, High-voltage switchgear and controlgear – Part 200: AC metal-enclosed
switchgear and controlgear for rated voltages above 1 kV and up to and including 52 kV
IEC 62855, Nuclear power plants – Electrical power systems – Electrical power systems
analysis
ISO/IEC 17025, General requirements for the competence of testing and calibration
laboratories
ISO 9712:2012, Non-destructive testing – Qualification and certification of NDT personnel
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminological databases for use in standardization at the following
addresses:
• IEC Electropedia: available at http://www.electropedia.org/
• ISO Online browsing platform: available at http://www.iso.org/obp
3.1
acceptance criteria
specified bounds on the value of a functional indicator or condition indicator used to assess
the ability of a structure, system or component to perform its design function
[SOURCE: IAEA Safety Glossary 2016 edition]
3.2
accident conditions
deviations from normal operation that are less frequent and more severe than anticipated
operational occurrences
EXAMPLE Examples of such deviations include a major fuel failure or a loss of coolant accident.
Note 1 to entry: Accident conditions comprise design basis accidents and design extension conditions.
[SOURCE: IAEA Safety Glossary 2016 edition]
3.3
ageing
general process in which characteristics of a structure, system or component gradually
change with time or use
[SOURCE: IAEA Safety Glossary edition 2016]
3.4
analysis
process and result of a study aimed at understanding the subject of the analysis, while
assessment may also include determinations or judgements of acceptability
Note 1 to entry: The term "analysis" is often used interchangeably with assessment. The term "assessment" may
also include determinations or judgements of acceptability. Analysis is also often associated with the use of a
specific technique. Hence, one or more forms of analysis may be used in assessment.
[SOURCE: IAEA Safety Glossary edition 2016]

3.5
anticipated operational occurrence
deviation of an operational process from normal operation that is expected to occur at least
once during the operating lifetime of a facility but which, in view of appropriate design
provisions, does not cause any significant damage to items important to safety or lead to
accident conditions
EXAMPLES Examples of anticipated operational occurrences are loss of normal electrical power and faults such
as a turbine trip, malfunction of individual items of a normally running plant, failure to function of individual items of
control equipment, and loss of power to the main coolant pump.
Note 1 to entry: Some States and organisations use the term abnormal operation (for contrast with normal
operation) for this concept.
[SOURCE: IAEA Safety Glossary edition 2016]
3.6
assessment
process and result, of analysing systematically and evaluating the hazards associated with
facilities and activities, and associated protection and safety measures
Note 1 to entry: Assessment is often aimed at quantifying performance measures for comparison with criteria.
Note 2 to entry: Assessment should be distinguished from analysis. Assessment is aimed at providing information
that forms the basis of a decision on whether or not something is satisfactory. Various kinds of analysis may be
used as tools in doing this. Hence an assessment may include a number of analyses.
[SOURCE: IAEA Safety Glossary edition 2016]
3.7
conductor module
assembly of electrical conductors and/or optical fibres and sealing material in one module
3.8
containment
methods or physical structures designed to prevent or control the release and the dispersion
of radioactive substances
[SOURCE: IAEA Safety Glossary edition 2016]
3.9
design basis
range of conditions and events taken explicitly into account in the design of structures,
systems and components and equipment of a facility, according to established criteria, such
that the facility can withstand them without exceeding authorized limits
Note 1 to entry: Used as a noun, with the definition above. Also often used as an adjective, applied to specific
categories of conditions or events to mean ‘included in the design basis’; as, for example, in design basis accident,
design basis external events and design basis earthquake.
[SOURCE: IAEA Safety Glossary 2016 edition]
3.10
design basis accident
postulated accident leading to accident conditions for which a facility is designed in
accordance with established design criteria and conservative methodology, and for which
releases of radioactive material are kept within acceptable limits
[SOURCE: IAEA Safety Glossary 2016]

– 14 – IEC 60772:2018 © IEC 2018
3.11
design basis events
DBE
group of design basis accidents and anticipated operational occurrences
[SOURCE: IEC 61226:2009, 3.4]
3.12
design extension condition
DEC
postulated accident conditions that are not considered for design basis accidents, but that are
considered in the design process of the facility in accordance with best estimate methodology,
and for which releases of radioactive material are kept within acceptable limits. Design
extension conditions include conditions in events without significant fuel degradation and
conditions with core melting
[SOURCE: IAEA Safety Glossary edition 2016]
3.13
electric penetration assembly
EPA
assembly of insulated electric conductors, conductor seals, and opening seals that provides
the passage for the electric conductors through a single opening in the nuclear containment
structure, while providing one or more physical barriers between the inside and the outside of
the containment structure
3.14
environmental conditions
physical conditions external to the EPA including, but not limited to, ambient temperature,
pressure, radiation, humidity, chemical spray, etc., expected as a result of normal operating
requirements and postulated initiating events
3.15
EPA/containment interface
is dependent on the EPA type as well as the options for installation (bolted / welded). F
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