IEC 62342:2007

IEC 62342
Edition 1.0 2007-08
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Nuclear power plants – Instrumentation and control systems important to
safety – Management of ageing
Centrales nucléaires de puissance – Systèmes d’instrumentation et de
contrôle-commande importants pour la sûreté – Gestion du vieillissement
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IEC 62342
Edition 1.0 2007-08
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Nuclear power plants – Instrumentation and control systems important to
safety – Management of ageing
Centrales nucléaires de puissance – Systèmes d’instrumentation et de
contrôle-commande importants pour la sûreté – Gestion du vieillissement

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
PRICE CODE
INTERNATIONALE
X
CODE PRIX
ICS 27.120.20 ISBN 2-8318-9260-0

– 2 – 62342 © IEC:2007
CONTENTS
FOREWORD.4
INTRODUCTION.6

1 Scope.8
1.1 Management of physical ageing .8
1.2 Management of technology ageing (obsolescence).8
1.3 Safety goal of this standard.8
2 Normative references .8
3 Terms and definitions .8
4 Background .11
5 Requirements for ageing management .12
5.1 General .12
5.2 Methodology.12
5.3 Process .13
6 Understanding I&C ageing phenomena.17
6.1 General .17
6.2 Stresses causing ageing .17
6.3 Ageing mechanisms and ageing effects.17
7 Requirements to address ageing effects .18
7.1 Ageing effect identification .18
7.2 Selection of I&C components for ageing evaluation .18
7.2.1 General .18
7.2.2 Identification of I&C functions, systems, and equipment .18
7.2.3 Breakdown of I&C equipment and components .18
7.2.4 Failure analysis .19
7.2.5 Susceptibility to ageing.19
7.3 Evaluating ageing degradation of I&C.20
7.4 Ageing stresses.20
7.4.1 General .20
7.4.2 External stresses influencing ageing.21
7.4.3 Internal stresses influencing ageing.21
7.4.4 Stress history and insecure conditions.21
7.5 Intended function versus qualification.22
7.5.1 Equipment specification and qualification .22
7.5.2 Impact on the qualification hypothesis .22
7.5.3 Applicability of ageing models .22
7.6 Surveillance tests and maintenance requirements .22
7.6.1 Maintenance and surveillance test processes .22
7.6.2 Ageing evidence from operating and maintenance research .22
7.6.3 Sample tests .22
7.7 Support resources .22
7.8 Documentation requirements.22
8 Requirements for ageing control.23
8.1 General .23
8.2 Definition of ageing control programs .23
8.3 Means for I&C ageing management.23

62342 © IEC:2007 – 3 –
9 Organization.24
9.1 General .24
9.2 Organization for ageing management .24
9.3 Identifying long-term operating strategies and I&C life cycle.24
9.4 Organization for the long-term maintenance of I&C equipment .25
9.5 Quality assurance .25
9.6 Reporting .25

Annex A (informative) Guidance on characterizing I&C ageing phenomena and
acquiring data for ageing management of I&C components in nuclear power plants .26
Annex B (informative) Examples of ageing management practices for selected I&C
components in nuclear power plants .29
Annex C (informative)  Examples of testing and monitoring techniques for I&C ageing
management.37

Bibliography.42

Figure B.1 – Bathtub curve model for failure rates of electronic components.29

Table 1 – Ageing management process as outlined in various clauses of this standard.13
Table B.1 – Potential effects of ageing on performance of nuclear plant pressure
transmitters.32
Table B.2 – Test methods for verifying the performance and monitoring the ageing of
I&C components .35

– 4 – 62342 © IEC:2007
INTERNATIONAL ELECTROTECHNICAL COMMISSION
______________
NUCLEAR POWER PLANTS –
INSTRUMENTATION AND CONTROL SYSTEMS
IMPORTANT TO SAFETY –
MANAGEMENT OF AGEING
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
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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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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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between any IEC Publication and the corresponding national or regional publication shall be clearly indicated in
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5) IEC provides no marking procedure to indicate its approval and cannot be rendered responsible for any
equipment declared to be in conformity with an IEC Publication.
6) All users should ensure that they have the latest edition of this publication.
7) No liability shall attach to IEC or its directors, employees, servants or agents including individual experts and
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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 62342 has been prepared by subcommittee 45A: Instrumentation
and control of nuclear facilities, of IEC technical committee 45: Nuclear instrumentation.
IEC 62342 is to be read in conjunction with IEC 62096 which is the appropriate IEC SC 45A
Technical Report which provides guidance on the decision for modernization when
management of ageing techniques is no longer successful.
The text of this standard is based on the following documents:
FDIS Report on voting
45A/660/FDIS 45A/665/RVD
Full information on the voting for the approval of this 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.

62342 © IEC:2007 – 5 –
The committee has decided that the contents of this publication will remain unchanged until
the maintenance result 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.
– 6 – 62342 © IEC:2007
INTRODUCTION
a) Technical background, main issues and organization of the standard
With the majority of NPPs over 20 years old, the management of the ageing of
instrumentation is currently a relevant topic, especially for those plants that have extended
their operating licences or are considering this option. This standard is intended to be used by
operators of NPPs (utilities), systems evaluators, and by licensors.
b) Situation of the current standard in the structure of the IEC SC 45A standard
series
IEC 62342 is the second-level IEC SC 45A document tackling the generic issue of
management of ageing of nuclear instrumentation.
IEC 62342 is the IEC SC 45A chapeau standard covering the domain of the management of
ageing of nuclear instrumentation systems used in NPPs 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 sensors,
transmitters, and cables.
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 the standard
It is important to note that this standard establishes no additional functional requirements for
safety systems. Ageing mechanism has to be prevented and thus detected by performance
measurements. Aspects for which special recommendations have been provided in this
Standard are:
• criteria for evaluation of ageing of I&C equipment in NPPs;
• steps to be followed to establish an ageing management program for NPP I&C equipment;
and
• tracking of performance indices such as response time and calibration stability as the
means to manage the ageing of sensors and transmitters.
It is recognized that testing and monitoring techniques used to evaluate the ageing condition
of NPPs’ I&C systems are continuing to develop at a rapid pace and that it is not possible for
a standard such as this to include references to all modern technologies and techniques.
However, a number of techniques have been mentioned within this standard and are
described in Annexes B and C.
To ensure that this standard will continue to be relevant in future years, the emphasis has
been placed on issues of principle, rather than specific technologies.
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,

62342 © IEC:2007 – 7 –
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 SC45 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 50-C/SG-Q) 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 Requirement 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 NPPs. The terminology and definitions used by
SC 45A standards are consistent with those used by the IAEA.

– 8 – 62342 © IEC:2007
NUCLEAR POWER PLANTS –
INSTRUMENTATION AND CONTROL SYSTEMS
IMPORTANT TO SAFETY –
MANAGEMENT OF AGEING
1 Scope
1.1 Management of physical ageing
This International Standard provides strategies, technical requirements, and
recommendations for the management of ageing of nuclear power plant (NPP)
instrumentation and control (I&C) systems and associated equipment. The standard also
includes informative annexes on test methods, procedures, and technologies that may be
used to verify proper operation of I&C equipment and aim to prevent ageing degradation from
having any adverse impact on the plant safety, efficiency, or reliability. The standard applies
to all types of NPPs and relates primarily to safety.
1.2 Management of technology ageing (obsolescence)
The scope of this standard has been intentionally focused on the management of physical
ageing of I&C systems where this may be considered as having a direct consequence on the
safety of the NPP. It does not cover technology ageing aspects (i.e., obsolescence) in any
detail.
It should be noted, however, that, in practice, the overall scheme for the management of
ageing will have to cover obsolescence. Indeed, obsolescence has been recognized as the
dominant issue in the life cycle of many I&C technologies (from design through to operational
maintenance, replacement, and updating).
1.3 Safety goal of this standard
This standard identifies minimum requirements aimed at ensuring that any potential impacts
on NPP safety due to I&C ageing can be identified and that suitable actions are undertaken to
demonstrate that the safety of the plant will not be impaired.
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 61513:2001, Nuclear power plants – Instrumentation and control for systems important to
safety – General requirements for systems
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1
accuracy of measurement
closeness of the agreement between the result of a measurement and the conventionally true
value of the measurand
62342 © IEC:2007 – 9 –
NOTE 1 “Accuracy” is a qualitative concept.
NOTE 2 The term “precision” should not be used for “accuracy”.
[IEV 394-40-35]
3.2
ageing
general process in which characteristics of a structure, system or component gradually
change with time or use
NOTE This degradation is due to physical mechanisms inherent in component materials and linked to the I&C
equipment design, assembly, and functional characteristics. It is influenced by the stresses from the equipment
environment and from the equipment operation.
[IAEA Safety Glossary, 2006]
3.3
calibration
set of operations that establish, under specified conditions, the relationship between values of
quantities indicated by a measuring instrument or a measuring system, or values represented
by a material measure or a reference material, and the corresponding values realized by
standards
NOTE For more details, see [IVM 6.11].
[IEV 394-40-43]
3.4
channel
arrangement of interconnected components within a system that initiates a single output. A
channel loses its identity where the single-output signals are combined with signals from an-
other channel (for example, from a monitoring channel or a safety actuation channel)
[IAEA Safety Glossary, 2006]
3.5
cross-calibration
procedure of intercomparing the indications of redundant instruments (for example,
temperature sensors) to identify outlier sensors as a means of verifying calibration or
identifying calibration changes. A more appropriate term for this definition is "cross-
validation," but, cross calibration is more commonly used
[IEC 62385, 3.6]
3.6
design life
period of time during which a facility or component is expected to perform according to the
technical specifications to which it was produced
[IAEA Safety Glossary, 2006]
3.7
I&C life cycle
set of necessary activities involved in the implementation and operation of an I&C system
occurring during a period of time that starts at a concept phase with the system requirements
specification and finishes when the I&C system is no longer available for use
3.8
in situ test
test of a sensor or a transmitter that is performed without removing the sensor or transmitter
from its normal installed position in the system

– 10 – 62342 © IEC:2007
[IEC 62385, 3.9]
3.9
installed life
time interval from installation to removal, during which the equipment or components thereof
may be subjected to design operational conditions
NOTE Equipment may have an installed life of 40 years with certain components changed periodically; thus the
installed life of the component would be less than 40 years.

[IEC 60780, 3.10]
3.10
modernization
replacement or upgrading with newer systems and components. Replacement is the term to
be used when there is no change in requirements; upgrading is the terms to be used when the
level of requirements increases
NOTE 1 Backfit, refit, retrofit, refurbish and upgrade are similar terms which are often used interchangeably. They
only differ in shades of meaning (IAEA-TECDOC-1066). Upgrading is the term to be used when there is an
increase in requirements. Upgrading also includes the implementation of new functionality.
NOTE 2 Replace and renew are similar and often interchangeable. The terms are used from a single component
up to the complete I&C.
3.11
monitoring
continuous or periodic measurement of radiation or other parameters for determination of the
status of a system
[IEV 393-18-40]
3.12
operating conditions
environmental, power, and signal conditions expected as a result of normal operation and
postulated initiating event conditions
3.13
performance limits
limits defining the quantitative static and dynamic characteristics of the input and output
subsystems measured during the operation/surveillance of the instrument channel for a given
environmental condition (for example, radiation, humidity, temperature, electromagnetic field,
etc.)
NOTE Instrument channel accuracy, response time, and stability are some of the attributes of performance limits.
3.14
predictive maintenance
form of preventive maintenance performed continuously or at intervals governed by observed
conditions to monitor, diagnose or trend a structure, system or component’s condition
indicators. Results indicate present and future functional ability or the nature of, and schedule
for, planned maintenance
NOTE It is also termed condition-based maintenance.
[IAEA Safety Glossary, 2006]
62342 © IEC:2007 – 11 –
3.15
preventive maintenance
actions that detect, preclude or mitigate degradation of a functional structure, system or
component to sustain or extend its useful life by controlling degradation and failures to an
acceptable level
NOTE 1 Preventive maintenance may be periodic maintenance, planned maintenance or predictive maintenance.
NOTE 2 Contrasted with corrective maintenance.
[IAEA Safety Glossary, 2006]
3.16
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, 2006]
3.17
response time
period of time necessary for a component to achieve a specified ouput state from the time that
it receives a signal requiring it to assume that output state
[IAEA Safety Glossary, 2006]
3.18
time constant
in the case of a first-order system, time required for the output signal of a system to reach
63,2 % of its final variation after a step change of its input signal.
If the system is not first-order system, the term “time constant” is not appropriate. For a
system of a higher order, the term “response time” should be used
[IEC 62397, 3.9]
3.19
trending analysis
process of obtaining instrument data over time to form a history of the instrument channel or
its components (for example, calibration) or compared to redundant instruments (for example,
cross-calibration/comparison) to determine if the performance has been affected
3.20
upgrading
refurbishment of equipment with design or functional enhancements based on operating
experience and new technology/materials availability. These include changing to materials
more resistant to ageing stressors, reconfiguring for improved reliability, even relocating
equipment and implementation of new functionality
4 Background
Experience throughout the utility and process industries has shown that the increasing age of
I&C systems in older plants could lead to deterioration of operability and maintainability. The
problem is also shared by NPPs. Maintaining adequate performance and dependability of I&C
is governed by two main issues:
a) physical ageing of the I&C equipment leading to defects;

– 12 – 62342 © IEC:2007
b) obsolescence of equipment (systems and components) in terms of both replacement parts
and suppliers’ support.
NPP I&C applications raise special lifetime dependability problems due to the relatively long-
life expectancy of the plant compared to that of the I&C, exposure to ionizing radiation, and
the demanding qualification requirements for safety systems.
As well as being necessary to ensure industrial asset management and economical plant
operation, the control or management of ageing of I&C in NPPs may be a formal obligation to
be demonstrated to the nuclear safety authority. One solution is to systematically renew I&C
at or before the onset of any ageing problems. However, many plant I&C installations have
not been designed with this option in mind and are not amenable to quick and simple
replacement with equivalent systems. The use of nuclear specific I&C, installation in restricted
(radioactive) working environments, safety licensing authority approval, and cost of long plant
outages are only a few examples of why upgrading the I&C can be a long, complex, and
expensive activity. Another approach is to prolong the use of the existing I&C by taking
appropriate measures to maintain the equipment. The annexes to this document provide
examples of measures that are implemented in NPPs to cope with the ageing of nuclear plant
I&C equipment.
5 Requirements for ageing management
5.1 General
This clause provides requirements and recommendations to establish the methodological
approaches and the practical processes necessary for I&C ageing management.
5.2 Methodology
A suitable methodology for the management of ageing of I&C which allows all relevant and
interacting issues of long-term plant operating strategies to be evaluated with respect to
safety shall be established.
Potential impacts on NPP safety due to I&C ageing shall be identified and suitable actions
shall be undertaken to demonstrate that the safety of the plant will not be impaired.
Furthermore, the qualification of the I&C shall be maintained. In addition, during the
estimation of the effects of ageing mechanism on an equipment or component, it is necessary
to consider both
a) those which could lead to failure during normal conditions; and
b) those which could lead to failure during accidental conditions (including seismic and
design basis accident conditions).
The parameters relevant to I&C ageing affecting safety (for example, calibration drift,
response time degradation) shall be identified and the means and methods used to acquire
data for verification of performance of I&C equipment shall be established. The I&C
performance data should be obtained periodically, analysed, and compared with acceptance
criteria. Since it is difficult to identify ageing mechanisms completely, it is important to
establish an efficient information feedback system taking advantage of experience from NPPs
and other industries. Of course, the quality of information sources should be controlled by
audits. The methodology used should take into consideration the foreseeable evolution of
functional needs, material performances, component supply, and human resources that are
needed to maintain the required targets for plant availability and preserve the plant safety.
The basic methodology of ageing management should involve the following three conceptual
steps in an iterative way.
62342 © IEC:2007 – 13 –
a) Understanding the ageing phenomenon and identifying the (potential) effects on I&C. This
understanding may be gained from research, operating experience, and other resources
(see Clause 6).
b) Evaluating the specific impact of these effects on the plant taking into account operational
profiles and analysing the risks, selecting I&C equipment and component items, analysing
the NPP operating conditions, and evaluating ageing degradation (see Clause 7).
c) Carrying out necessary mitigating actions to counteract the effects of ageing, defining
specific means for I&C ageing management such as improved testing and maintenance,
establishing “ageing control” programs, and developing modification and replacement
strategies (see Clause 8 and annexes).
Due to the importance of I&C to plant safety, ageing management in practice shall be
prioritized. This may be achieved by selecting I&C equipment and components according to
susceptibility to ageing, operating conditions, and impact of failure on the safety of the system
to which they belong.
Condition monitoring of the plant and of the I&C equipment is necessary either as part of the
preliminary (“one-off”) evaluation to identify ageing equipment and/or as a continued long-
term action before replacing the equipment.
The means for I&C ageing management will include existing arrangements, provisions by
design, maintenance, surveillance testing, etc., the adequacy of which must be verified. It
may be necessary to define additional means for I&C ageing management such as improved
maintenance, specific “ageing control” programs, modification and replacement strategies.
5.3 Process
The methodology considerations given in 5.2 shall be implemented in an ageing management
process. The process for management of physical ageing of I&C shall comprise actions to
identify the parts of the equipment having characteristics changing with time and follow these
up with necessary testing and surveillance as well as corrective or mitigating measures to
ensure dependability, performance and, where applicable, qualified life. This may be
organized as a programme of specific actions to address ageing, as a verification of existing
(short- and long-term) maintenance activities, or a combination of both. Table 1 shows how
the ageing management process is presented by the different clauses of this document. The
requirements and recommendations concerning actual practical steps made in the ageing
management process are detailed in the clauses which follow. The steps in an I&C ageing
management process are illustrated in the flowchart of Figure 1.
Table 1 – Ageing management process as outlined
in various clauses of this standard
Introduction
P
Clause 1. Scope
R
Describes the scope of the standard with respect to the management of physical ageing of NPP I&C,
E
technology ageing, and impact on nuclear safety.
L
I
Clause 2. Normative references
M
IEC standards that relate to this standard are listed in this clause.
I
N
Clause 3. Terms and definitions
A
The terms used in this standard are all defined in this clause.
R
Clause 4. Background Y
This clause contains a general background on why I&C ageing management is important.

– 14 – 62342 © IEC:2007
Clause 5. Requirements for ageing management

This clause describes the methodological approach and the practical processes necessary for ageing

management.
R
5.1 General 5.2 Methodology 5.3 Process
E
C
Clause 6. Understanding I&C ageing phenomena
O
Characterizing the ageing phenomena and identifying the (potential) effects on I&C from knowledge gained
M
from research, operating experience, and other resources.
M
E
6.1 General 6.2 Stresses causing ageing 6.3 Ageing mechanisms and ageing
N
effects
D
Clause 7. Requirements to address ageing effects
A
Evaluating the specific impact of ageing effects on the plant taking into account operational profiles and
T
analysing the risks.
I
O
7.1 7.2 7.3 7.4 7.5
7.6 7.7 7.8
N
Ageing Selection of Evaluating Ageing Intended Surveillance Support Docu-
S
effect I&C ageing stresses function tests and resources mentation

identifi- components degradation versus maintenance require-
cation for ageing of I&C qualification requirements &
ments
evaluation
R
Clause 8. Requirements for ageing control
E
Carrying out necessary mitigating actions to counteract the effects of ageing by defining specific means for Q
I&C ageing management such as improved testing and maintenance or “ageing control” programmes.
U
I
8.1 General 8.2 Definition of ageing control programs 8.3 Means for I&C ageing management
R
E
M
Clause 9. Organization
E
Organising the ageing management process including the definition of long-term strategies, I&C life cycle,
quality control, and reporting. N
T
9.1 General 9.2 Organization 9.3 Identifying long- 9.4 Organization for 9.5 Quality 9.6 Reporting S
for ageing term operating the long-term assurance
management strategies and I&C maintenance of I&C
life cycle equipment
Annex A
Guidance on characterizing I&C ageing phenomena and acquiring data for ageing management of I&C
components in nuclear power plants

A.1 Examples of stress factors, A.2 Data for ageing management A.3 Testing and monitoring

ageing mechanisms, and
ageing effects on different I&C
components
Annex B
Examples of ageing management practices for selected I&C components in nuclear power plants

62342 © IEC:2007 – 15 –
B.1 Management of ageing of B.2 B.3 Management of B.4 Ageing B.5 Application I
electronics and electrical Management ageing of neutron flux management for normal
N
components of ageing of detectors for cables and operation and
F
temperature connectors post-accident
O
and pressure conditions
sensors R
M
Annex C
A
Examples of testing and monitoring techniques for I&C ageing management
T
I
C.1 On-line calibration C.2 On-line C.3 In situ response C.4 On-line detection of clogging
V
verification detection of time testing of in impulse lines
E
venturi fouling pressure transmitters

C.5 RTD and thermocouple C.6 Response C.7 Testing of cables C.8 Assurance of I&C reliability
cross calibration time testing of and connectors in accident conditions
RTDs and
thermocouples
Bibliography
IAEA documents IEC documents Other documents

– 16 – 62342 © IEC:2007
Establish/define/agree upon
the scope of ageing management process

(Reference: Clauses 1 to 4)
Define ageing management
requirements, methodology, and process

(Reference: Clauses 5 and 6)
Select I&C components for
ageing evaluation and identify ageing stresses

(Reference: Clauses 6 and 7)
Identify testing and surveillance
means and maintenance requirements
to mitigate the consequences of ageing

(References Clauses 7 and 8
and Annexes A, B, and C)
Document the ageing management process
including the organizational aspect of the
ageing management, quality assurance
considerations, plant’s long-term strategy, and
how testing and surveillance data and results
should be reported and maintained

(Reference: Clause 9)
IEC  1377/07
Figure 1 – Flowchart of ageing management process for I&C equipment and systems

62342 © IEC:2007 – 17 –
6 Understanding I&C ageing phenomena
6.1 General
Possible ageing phenomena should be characterized to identify and associate ageing
mechanisms, causes, and potential or authenticated effects on I&C components, equipment,
and systems. The list of ageing phenomena shall be updated periodically as experience is
accumulated from plant operation and from external sources of information (for example,
R&D, experience).
Toward the end of an I&C component’s lifetime, the failure rate of the component and hence
the I&C equipment or system becomes greater (wear-out failure period of the “bathtub”
reliability curve – see Annex B). At this point, the failure rate is no longer statistically
predictable and hence the equipment becomes unreliable. The influence of stresses can
effectively cause premature ageing. As such, testing and surveillance should be increased as
I&C ageing progresses.
6.2 Stresses causing ageing
Stresses originate from manufacture, storage, and pre-service or in-service operating
conditions. They produce failures due to wear and may induce ageing mechanisms and
produce ageing effects. They can be considered as two types.
a) External stresses exist in the environment surrounding the equipment, whether it is
operating or shutdown. Typical examples include temperature, humidity, radiation,
electrical, and vibration. These stresses may vary in intensity depending on external
events (climatic changes, plant events, hazards, electrical discharge, electromagnetic
field, etc.) and location.
b) Internal stresses arise from equipment or system operation. Examples are internal heating
from electrical or mechanical loading, physical stresses from mechanical or electrical
surges, vibration, and electrical or mechanical wearing of parts from equipment operation
(for e
...