IEC 62465:2010
(Main)Nuclear power plants - Instrumentation and control important to safety - Management of ageing of electrical cabling systems
Nuclear power plants - Instrumentation and control important to safety - Management of ageing of electrical cabling systems
IEC 62465:2010 provides strategies, technical requirements, and recommended practices for the management of normal ageing of cabling systems that are important to safety in nuclear power plants. The main requirements are presented in the body of this International Standard followed by a number of informative annexes with examples of cable testing techniques, procedures, and equipment that are available for the nuclear industry to use to ensure that ageing degradation will not impact plant safety.
This publication contains colours which are considered to be useful for the correct understanding of its contents.
Centrales nucléaires de puissance - Instrumentation et contrôle-commande importants pour la sûreté - Gestion du vieillissement des systèmes de câbles électriques
La CEI 62465:2010 fournit des stratégies, des exigences techniques et des pratiques recommandées pour la gestion du vieillissement normal des systèmes de câbles qui sont importants pour la sûreté en centrale nucléaire. Les exigences principales sont présentées dans le corps de la norme qui est suivi d'un certain nombre d'annexes informatives présentant des exemples de techniques, de procédures et de matériels pour l'essai des câbles qui sont disponibles pour garantir à l'industrie nucléaire que les dégradations liées au vieillissement n'impactent pas la sûreté des installations.
Cette publication indique qu'elle contient des couleurs qui sont considérées comme utiles à une bonne compréhension de son contenu.
General Information
Standards Content (Sample)
IEC 62465 ®
Edition 1.0 2010-05
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
Nuclear power plants –
Instrumentation and control important to safety – Management of ageing of
electrical cabling systems
Centrales nucléaires de puissance –
Instrumentation et contrôle-commande importants pour la sûreté – Gestion du
vieillissement des systèmes de câbles électriques
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IEC 62465 ®
Edition 1.0 2010-05
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
Nuclear power plants –
Instrumentation and control important to safety – Management of ageing of
electrical cabling systems
Centrales nucléaires de puissance –
Instrumentation et contrôle-commande importants pour la sûreté – Gestion du
vieillissement des systèmes de câbles électriques
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
PRICE CODE
INTERNATIONALE
V
CODE PRIX
ICS 27.120.20 ISBN 978-2-88910-915-9
– 2 – 62465 © IEC:2010
CONTENTS
FOREWORD.4
INTRODUCTION.6
1 Scope.8
2 Normative references .8
3 Terms and definitions .8
4 Technical background.11
4.1 General .11
4.2 Cable types .11
4.3 Reasons for cable ageing management .12
4.4 Cable stressors .12
4.5 Cable testing techniques .13
5 Cable testing requirements.13
5.1 General .13
5.2 Test methods .14
5.3 Application of cable testing requirements .14
5.4 Test interval .14
5.5 Test location .14
5.6 Calibration of cable testing equipment.14
5.7 Test results .14
5.8 Validation of test methods .14
5.9 Software and test tool validation.15
5.10 Qualification of test personnel .15
6 Acceptable means for cable testing .15
7 Testing of end devices.15
8 Relationship between initial qualification and cable ageing management .16
9 Example of a nuclear power plant practice for cable ageing management.16
10 Cable testing for long-term operation.16
Annex A (informative) Typical components of an electrical cable .17
Annex B (informative) Cable testing techniques .20
Annex C (informative) Description of TDR test .22
Annex D (informative) Electrical measurement of NIS cables and detectors .26
Annex E (informative) Example of a nuclear power plant practice for cable ageing
management.28
Bibliography.31
Figure A.1 – Example of cables covered by this International Standard.18
Figure C.1 – Principle of TDR test of an open cable.22
Figure C.2 – Principle of TDR test of a short cable.23
Figure C.3 – Simplified TDR traces for a cable with a passive load .23
Figure C.4 – TDR test setup .24
Figure C.5 – RTD cabling and corresponding TDR signature .25
Figure D.1 – I-V curve.27
62465 © IEC:2010 – 3 –
Figure E.1 – Photo of baskets in which samples of 1E cables are deposited and placed
in the plant for periodic removal and testing.29
Figure E.2 – Schematic of test interval for mechanical tests.30
Table 1 – Examples of stressors with potential to damage cables .13
– 4 – 62465 © IEC:2010
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
NUCLEAR POWER PLANTS –
INSTRUMENTATION AND CONTROL IMPORTANT TO SAFETY –
MANAGEMENT OF AGEING OF ELECTRICAL CABLING SYSTEMS
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
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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 62465 has been prepared by subcommittee 45A: Instrumentation
and control of nuclear facilities, of IEC technical committee 45: Nuclear instrumentation.
The text of this International Standard is based on the following documents:
FDIS Report on voting
45A/795/FDIS 45A/803/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 publication has been drafted in accordance with the ISO/IEC Directives, Part 2.
62465 © IEC:2010 – 5 –
The committee has decided that the contents of this publication will remain unchanged until
the stability 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.
IMPORTANT – The 'colour inside' logo on the cover page of this publication indicates
that it contains colours which are considered to be useful for the correct
understanding of its contents. Users should therefore print this document using a
colour printer.
– 6 – 62465 © IEC:2010
INTRODUCTION
a) Technical background, main issues and organisation of the Standard
With the majority of nuclear power plants over 20 years old, the management of ageing of
instrumentation and associated electrical cabling systems is currently a relevant topic,
especially for those plants that have extended their operating licenses or are considering this
option. This International Standard is intended to be used by operators of nuclear power
plants (utilities), systems evaluators, and by licensors.
b) Situation of the current Standard in the structure of the IEC SC 45A standard series
IEC 62465 is the third level IEC SC 45A document tackling the specific issue of management
of ageing of electrical cabling systems in nuclear power plants for Instrumentation and Control
(I&C) systems important to safety.
IEC 62342 is the second level chapeau standard of SC 45A covering the domain of the
management of ageing of nuclear instrumentation systems used in nuclear power plants to
perform functions important to safety. IEC 62342 is the introduction to a series of standards to
be developed by IEC SC 45A covering the management of ageing of specific I&C systems or
components such as electrical cabling systems (IEC 62465), sensors, and transmitters.
IEC 62465 is to be read in association with IEC 62342 and IEC 62096, which is the
appropriate IEC SC 45A Technical Report that provides guidance on the decision for
modernization when management of ageing techniques are no longer successful.
For more details on the structure of the IEC SC 45A standard series, see item d) of this
introduction.
c) Recommendations and limitations regarding the application of this Standard
It is important to note that this International Standard establishes no additional functional
requirements for safety systems. Ageing mechanisms have to be prevented and thus detected
by performance measurements. Aspects for which special recommendations have been
provided in this International Standard are:
• criteria for evaluation of ageing of electrical cabling systems in nuclear power plants;
• steps to be followed to establish cable testing requirements for an ageing management
program for nuclear power plant electrical cabling systems; and
• relationship between on-going qualification analysis and ageing management programs
with regards to electrical cabling systems.
It is recognized that testing and monitoring techniques used to evaluate the ageing condition
of nuclear power plants’ electrical cabling systems are continuing to develop at a rapid pace
and that it is not possible for a standard such as IEC 62465 to include references to all
modern technologies and techniques. However, a number of techniques have been mentioned
within this International Standard and are described in Annexes B, C and D.
To ensure that this International Standard will continue to be relevant in future years, the
emphasis has been placed on issues of principle, rather than specific technologies.
62465 © IEC:2010 – 7 –
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 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.
IEC 61513 has adopted a presentation format similar to the basic safety publication
IEC 61508 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 terminology and
definitions used by SC 45A standards are consistent with those used by the IAEA.
– 8 – 62465 © IEC:2010
NUCLEAR POWER PLANTS –
INSTRUMENTATION AND CONTROL IMPORTANT TO SAFETY –
MANAGEMENT OF AGEING OF ELECTRICAL CABLING SYSTEMS
1 Scope
This International Standard provides strategies, technical requirements, and recommended
practices for the management of normal ageing of cabling systems that are important to
safety in nuclear power plants. The main requirements are presented in the body of this
International Standard followed by a number of informative annexes with examples of cable
testing techniques, procedures, and equipment that are available for the nuclear industry to
use to ensure that ageing degradation will not impact plant safety.
This International Standard covers cables and their accessories (e.g., connectors) installed in
nuclear power plants (inside and outside the containment). It provides requirements to
perform cable testing for the purposes of predictive maintenance, troubleshooting, ageing
management, and assurance of plant safety. It is concerned with Instrumentation and Control
(I&C) cables, signal cables, and power cables of voltages less than 1 kV. More specifically,
this International Standard focuses on in-situ testing techniques that have been established
for determining problems in cable conductors (i.e., copper wire) and, to a lesser extent, on
insulation material (i.e., polymer). It follows the IEC 62342 standard on “Management of
Ageing” that was prepared to provide general guidelines for management of ageing of I&C
components in nuclear power plants, including cables. It should be pointed out that cable
testing technologies are evolving and new methods are becoming available that are not
covered in this International Standard. More specifically, this International Standard covers
typical cable testing methods that have been in use in the nuclear power industry over the last
decade. It should also be pointed out that a single cable testing technique is unlikely to
provide conclusive results, and a reliable diagnosis normally requires a combination of
techniques.
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 60780, Nuclear power plants – Electrical equipment of the safety system – Qualification
IEC/TR 62096, Nuclear power plants – Instrumentation and control important to safety –
Guidance for the decision on modernization
IEC 62342, Nuclear power plants – Instrumentation and control systems important to safety –
Management of ageing
IEC 62385, Nuclear power plants – Instrumentation and control important to safety – Methods
for assessing the performance of safety system instrument channels
IEC/TR 62392, Suitability of typical electrical insulating material (EIM) for polymer recycling
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
62465 © IEC:2010 – 9 –
3.1
accelerated ageing
accelerated process designed to simulate an advanced life condition in a short period of time.
It is the process of subjecting an equipment or a component to stress conditions in
accordance with known measurable physical or chemical laws of degradation in order to
render its physical and electrical properties similar to those it would have at an advanced age
operating under expected operational conditions.
[IEC 60780]
3.2
ageing assessment
evaluation of appropriate information for determining the effects of ageing on the current and
future ability of systems, structures, and components to function within acceptance criteria in
all operating conditions (e.g., in normal conditions and after design basis events)
3.3
ageing management
engineering, operations, and maintenance actions to control within acceptable limits ageing
degradation of structures, systems, or components
[IAEA Safety Glossary, 2007 edition]
3.4
cable deposit (cable depot)
selection of cable samples placed inside a nuclear power plant for condition monitoring or
removal for testing
3.5
cable indenter
means for testing the indenter modulus of a cable’s insulation or jacket material
3.6
cabling system
system of cables, including the conductor, shielding, splices, insulation material, and the
cable accessories (e.g., connectors)
3.7
Design Basis Accident
DBA
accident conditions against which a facility is designed according to established design
criteria, and for which the damage to the fuel and the release of radioactive material are kept
within authorized limits
[IAEA Safety Glossary, 2007 edition]
3.8
environmental monitoring
monitoring of severities of ambient environmental parameters (e.g., temperature and radiation
dose)
3.9
environmental stress
factor influencing at least one ageing mechanism of the cabling system which is not caused
by the change of its physical state
– 10 – 62465 © IEC:2010
3.10
equipment qualification
generation and maintenance of evidence to ensure that equipment will operate on demand,
under specified service conditions, to meet system performance requirements
[IAEA Safety Glossary, 2007 edition]
3.11
high-stress area (hot spot)
limited part of cable subject to more severe environmental stress (irradiation, temperature,
mechanical constraints). Areas often localized within a nuclear power plant where
temperatures and/or radiation dose rates are higher than expected.
3.12
in-situ cable test
testing that is performed without removing the cabling system from its normal installed
position in the plant
3.13
Insulation Resistance (IR) measurement
measurement of resistance between a conductor and ground or between any two electrical
conductors
3.14
I-V curve
plot of the relationship between Current (I) and Voltage (V) for a neutron detector
3.15
LCR measurement
measurement of Inductance (L), Capacitance (C), and Resistance (R) of a cabling system
3.16
Loop Current Step Response (LCSR) test
method for measurement of response time of temperature sensors and for separating sensor
problems from cable problems
3.17
noise analysis technique
method for in-situ response time testing of sensors, detectors, and transmitters and for on-line
detection of blockages, voids, and leaks in pressure sensing lines
[IEC 62385]
NOTE This method is also used to identify ageing degradation in sensors such as neutron detectors and can help
separate sensor problems from cable problems.
3.18
Nuclear Instrumentation System
NIS
instrument chain used to measure neutron flux
3.19
qualified life
period for which a structure, system or component has been demonstrated, through testing,
analysis or experience, to be capable of functioning within acceptance criteria during specific
operating conditions while retaining the ability to perform its safety functions in a design basis
accident or earthquake
[IAEA Safety Glossary, 2007 edition]
62465 © IEC:2010 – 11 –
3.20
Resistance Temperature Detector
RTD
temperature sensor containing a sensing element made of platinum or other metals whose
resistance changes with temperature
3.21
test interval
elapsed time between the initiation of identical tests on the same sensor and signal
processing device, logic assembly or final actuation device
[IEC 60671]
3.22
Time Domain Reflectometry (TDR) test
method for locating faults along a cable, in the connector, and/or at the end device
4 Technical background
4.1 General
Cabling systems in nuclear power plants can suffer degradation due to ageing and shall
require testing to ensure proper plant operation and safety. For example, cables can become
dry and embrittled due to ageing and malfunction during plant operation or in accident and
post-accident conditions. In a Loss-of-Coolant Accident (LOCA), cables are subjected to hot
steam under high pressure and can malfunction if there is any insulation ageing, cracks, or
other damage that can allow moisture to enter the cable. The combination of hot steam and
high pressure is the dominating reason for possible cable malfunction in a LOCA especially
because steam penetrates smaller cracks more easily than water. Ageing of cable insulation
materials is covered in IEC 62392.
In addition to problems that can arise from cable insulation damage, there are problems due
to cable conductors, connectors, or accessories. These problems can cause measurement
errors, erratic signals, spikes, noise, and other anomalies that interfere not only with efficient
operation and control of the plant but also with plant safety. This International Standard
provides requirements and guidelines to identify these problems.
4.2 Cable types
Cables in nuclear power plants can typically be grouped into the following functional types:
a) instrumentation and control cables (coaxial, triaxial, twisted pair, shielded),
b) low voltage power cables (less than 1 kV),
c) medium voltage power cables (e.g., less than 30 kV),
d) general services cables (ground cables, communication cables, etc.).
The main focus of this International Standard is on I&C cables although many of the aspects
considered here are also applicable to low voltage power cables, as they use similar materials
and experience similar degradation mechanisms. For example, the methods described here
are used for testing the control rod drive mechanism (CRDM) cables and other similar cables
in nuclear power plants.
Instrumentation cables (including thermocouple extension wires) are normally low voltage
(typically <1 kV). Typically, they are used for digital or analog transmission of sensor or
instrument signals. Resistance temperature detectors, pressure transducers, and some
thermocouple extension leads usually are of a shielded and twisted pair configuration (most
thermocouple extension wires are made of mineral insulated cables). Radiation detection and
neutron monitoring circuits often use coaxial or triaxial shielded configurations. Control cables
– 12 – 62465 © IEC:2010
for auxiliary components such as control switches, valve operators, relays, and contactors are
usually of a low voltage, low current type. They are often made of multi-conductor cables, with
shielding for application near high voltage systems. Low voltage power cables (<1 kV) are
used to supply power to low voltage auxiliary devices such as motors, motor control centres,
heaters, and small transformers. These cables may be single conductor or multi-conductor
and are usually unshielded.
Typically, a cable consists of four to eight components. For example, the main components
for an I&C or a low voltage power cable are:
• conductor(s),
• electrical insulation or dielectric,
• shielding,
• outer jacket.
In some cables, particularly control and low voltage power cables, there may be a jacketing
layer over the insulation on the individual conductors, providing fire retardance. This is usually
referred to as a conductor jacket or inner jacket if it is present. In general, the term jacket
would normally refer to the outer layer of the cable construction. Other components which
may be present in a cable include:
• filler or bedding materials, which occupy the gaps between insulated conductors in multi-
conductor (also known as multi-core) cables, to improve mechanical stability of the cable;
• tape wraps, which may provide additional electrical, mechanical or fire protection, or
identify conductor groupings;
• armouring layers, which are sometimes used for mechanical protection under the outer
jacket layer.
Annex A provides a description of a typical cable and the components that are normally
involved in the testing activity covered in this International Standard.
4.3 Reasons for cable ageing management
Cable testing is performed in nuclear power plants for a number of reasons such as
troubleshooting, to identify problems such as signal anomalies, to establish baseline
measurements as a reference for predictive maintenance, and to evaluate cable ageing.
In recent years, cable ageing management has become more important for two main reasons.
Firstly, some plants have obtained licence renewal to operate cables for an extended qualified
life. Secondly, the nuclear power industry has recognized that there are limitations in cable
qualification testing in the areas of pre-ageing and the use of models such as the Arrhenius
law for assessing qualified life.
A challenge in management of ageing of cables and determination of problems is in detection
of hot spots along a cable and how to locate the hot spot. Hot spots can occur due to
radiation effects, electrical heating effects, ambient heat, and mechanical stress and there is
no reliable in-situ technique to locate hot spots along a cable. In particular, cables are often in
conduits and means such as visual inspections do not provide effective diagnostics of cable
conditions.
4.4 Cable stressors
Ageing and degradation of cables results from long-term exposure to radiation, heat, humidity,
vibration, and other environmental stressors that exist in nuclear power plants. These also
include lubricants, chemicals, or contaminants that a cable may come into contact with in a
plant. Also, there are internal stressors such as ohmic heating from the passage of electric
currents in the cable. Both the cable insulation material and the conductor are affected by
ageing. Table 1 shows examples of ageing stressors with potential to damage cables.
Furthermore, mechanical stressors such as bending, squeezing, vibration, or a combination of
62465 © IEC:2010 – 13 –
these effects with other environmental stressors (synergism), can alter the ageing
characteristics of cables.
4.5 Cable testing techniques
To guard against the adverse consequences of cable ageing and degradation, periodic testing
and condition monitoring of cables should be performed in nuclear power plants especially for
those cables that are important to safety. For this purpose, numerous techniques have been
developed to measure ageing effects in cables and to identify effective cable maintenance
techniques. In Annexes B, C, and D of this International Standard, examples of basic testing
techniques for cables are described. These and other techniques which can meet the
requirements of this International Standard may be used to ensure reliable cable service and
protect the safety of nuclear plants against consequences of cable degradation and ageing.
NOTE This International Standard provides methods for assessing cable systems, including connectors and end
devices. Methods for assessing ageing degradation of cable insulation are covered in IEC 62392.
Table 1 – Examples of stressors with potential to damage cables
Ageing stressor Affected component Consequence
Corrosion/oxidation Conductor Increased resistance and self-
heating
Connector Increased resistance and self-
heating
Vibration Conductor Increased resistance, reduced
strength
Connector Reduced strength, reduced
connection quality
Insulation Formation of cracks, reduced
insulation resistance (IR) when
subjected to humidity, loss of
material
Heat and ionising radiation Insulation Changes in mechanical properties,
changes in flammability
characteristics, loss of additives
(plasticisers, anti-oxidants, etc.)
Moisture/water Insulation and conductor Acceleration of the effects of
radiation and thermal ageing,
deterioration of cable material,
shorting and shunting effects if
moisture enters the cable, reduction
of IR, swelling
Lubricants, contaminants Insulation material and connector Deterioration of insulation material
5 Cable testing requirements
5.1 General
The control and safety systems of nuclear power plants depend on reliability of cables in
operational conditions. Therefore, the performance of cables especially those having safety
relevance, shall be verified periodically during the plant life time. This is of particular concern
for cables supporting safety functions and cables whose failure could impact qualified
equipment and have consequences on plant safety.
This clause gives requirements for in-situ testing to verify that electrical cabling systems
provide reliable service and to ensure safety.
– 14 – 62465 © IEC:2010
5.2 Test methods
Test methods such as those described in the annexes of this International Standard have
been developed and used in nuclear power plants. These methods include in-situ test
methods which can be used while the plant is operating as well as methods for testing cable
samples. Any method for testing of safety-related cables shall be validated according to 5.8 of
this International Standard.
5.3 Application of cable testing requirements
This International Standard is applicable to instrumentation cable systems supplying
temperature, pressure (including level and flow), and neutron flux data. It is also useful for
cable systems supplying power to Control Rod Drive Mechanisms (CRDMs), rod position
indicators, motors, heater coils, Solenoid Operated Valves (SOVs), Motor Operated Valves
(MOVs), and similar components. Cables used with test sensors such as accelerometers,
humidity sensors, and the like may also be tested using the techniques described here.
5.4 Test interval
Test intervals shall be established to detect unacceptable performance. The following factors
should be considered in determining the test interval:
• cable age,
• cable type,
• cable material,
• manufacturer’s recommendation and other industry standards,
• margin between measured performance characteristics and desired performance,
• rate-of-change of performance characteristics with time,
• cable failure rates and target reliability.
5.5 Test location
Testing should be performed in-situ to the extent possible. Cable removal for testing is not
acceptable except for representative cables from cable deposits.
5.6 Calibration of cable testing equipment
Cable testing equipment shall have valid calibration traceable to national standards. Written
procedures shall be used to perform the calibration, and the results of the calibration shall be
documented.
5.7 Test results
Cable testing results shall be compared to the allowable performance limits if available. If the
results are found to exceed the limit, or the rate of change in the performance characteristics
is such that the allowable performance limits may be exceeded prior to the next test, action
shall be taken to address the problem.
5.8 Validation of test methods
Cable testing methods shall be validated to ensure that cable testing results correlate well to
the conditions of the cable. Validation of test methods using laboratory tests require several
preliminary phases to ensure that they are representative and reproducible measures of the
laboratory tests. This validation shall be documented and should address the following
considerations:
a) Test set-up definition:
62465 © IEC:2010 – 15 –
• definition of a set of test cases (cable types, defect types, various lengths, junctions,
etc.),
• identification of defects to be diagnosed (a complete list should be written),
• laboratory characterization of the various cables and other devices (junctions,
connectors, loads) with and without defects,
• characterization of environmental ageing (e.g., radiation and temperature) and its
consequences on the test methods.
b) Comparison of test method with suitable laboratory tests, in-situ tests, or both types of
tests to establish the validity of the method.
c) Theoretical justification for the test method.
d) The assumptions made and conditions used to ensure that the validity of the test method
has been established.
5.9 Software and test tool validation
Any software used for data acquisition, data qualification, or data analysis for cable testing
shall be designed and developed using a systematic approach according to accepted industry
standards for software development for nuclear power plants. All software packages shall go
through comprehensive Verification and Validation (V&V) testing. The basis for the V&V tests
and the results of the V&V work shall be documented. Also, any tools that are used for the
tests described here shall be qualified by a systematic Quality Assurance (QA) program to
ensure that they perform their function properly.
5.10 Qualification of test personnel
Testing to verify the performance of nuclear power plant cables shall be performed by
personnel who have been properly trained in cable testing. The training of the test personnel
shall be documented and updated periodically. Examples of training topics to qualify the test
personnel are:
• principles of cable testing,
• equipment for cable testing,
• training on data acquisition and data analysis software,
• interpretation and documentation of cable testing results.
6 Acceptable means for cable testing
Annexes B and C provide examples of methods that can be used for cable testing in nuclear
power plants. These and other methods can be used for cable testing in nuclear power plants
provided that they meet the requirements of this International Standard and are validated
according to the validation criterion identified in this International Standard for the methods,
software, and equipment that are used to conduct the tests.
7 Testing of end devices
I&C cables often end with sensors such as a Resistance Temperature Detector (RTD),
pressure transmitter, or neutron detector. Therefore, means shall be established to distinguish
problems in cable systems from problems in end devices. For example, the Loop Current Step
Response (LCSR) technique which is normally used for in-situ response time testing of RTDs,
has also proven useful in separating cable problems from RTD problems. For other sensors
such as neutron detectors and pressure transmitters, the noise analysis technique is used to
identify sensor anomalies. For a description of the noise analysis technique or the LCSR
method, refer to IEC 62385. The LCSR and noise analysis are examples of techniques that
can be used to distinguish between sensor problems and cable problems. There are other
methods that have been used or are under development.
– 16 – 62465 © IEC:2010
Annex D provides a summary of a particular set of cable testing techniques that can be used
together with the noise analysis technique to establish the ageing condition of Nuclear
Instrumentation Systems (NIS) in nuclear power plants. This procedure is used in nuclear
power plants to avoid premature replacement of neutron detectors or other NIS com
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