IEC TR 61244-4:2019

Determination of long-term radiation ageing in polymers - Part 4: Effects of different temperatures and dose rates under radiation conditions

IEC TR 61244-4:2019(E) provides general guidance for the evaluation/verification of electrical insulation materials (EIM) and electrical insulation systems (EIS) intended to be used in types of equipment exposed to ionizing radiation. Beside sensors, actuators/motors as well as plugs and terminals, cables are a well-known typical application of those EIM and EIS. Their type spectrum covers low voltage power cables, control cables and instrumentation cables. Because of their comparable simple design, cables are the ideal type of equipment to study EIM and EIS degradation processes. But the results of these studies can be easily transferred to the enumerated types of equipment.
Nonetheless, this document provides a state-of-the art report on qualification/verification procedures used to simulate simultaneous effects of temperature and radiation at varying intensities rather than give detailed test programmes valid for specific test methods.
NOTE 1 Use of this document with specific products can require specification of additional product related procedures.
NOTE 2 Some of the procedures described in this document are emerging technologies. Therefore, specified prerequisites, former experiences as well as boundary conditions can be additionally taken into account.

General Information

• Status: Published
• Publication Date: 24-Sep-2019
• ICS: 01 - GENERALITIES. TERMINOLOGY. STANDARDIZATION. DOCUMENTATION
• ICS: 17.240 - Radiation measurements
• ICS: 29.035.01 - Insulating materials in general
• Technical Committee: TC 112 - Evaluation and qualification of electrical insulating materials and systems
• Drafting Committee: WG 2 - TC 112/WG 2
• Current Stage: PPUB - Publication issued
• Start Date: 21-Oct-2019
• Completion Date: 25-Sep-2019

Standards Content (Sample)

IEC TR 61244-4 ®
Edition 1.0 2019-09
TECHNICAL
REPORT
Determination of long-term radiation ageing in polymers –
Part 4: Effects of different temperatures and dose rates under radiation
conditions
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form
or by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from
either IEC or IEC's member National Committee in the country of the requester. If you have any questions about IEC
copyright or have an enquiry about obtaining additional rights to this publication, please contact the address below or
your local IEC member National Committee for further information.

IEC Central Office Tel.: [phone]
3, rue de Varembé [e-mail]
CH-1211 Geneva 20 www.iec.ch
Switzerland
About the IEC
The International Electrotechnical Commission (IEC) is the leading global organization that prepares and publishes
International Standards for all electrical, electronic and related technologies.

About IEC publications
The technical content of IEC publications is kept under constant review by the IEC. Please make sure that you have the
latest edition, a corrigendum or an amendment might have been published.

IEC publications search - webstore.iec.ch/advsearchform Electropedia - www.electropedia.org
The advanced search enables to find IEC publications by a The world's leading online dictionary on electrotechnology,
variety of criteria (reference number, text, technical containing more than 22 000 terminological entries in English
committee,…). It also gives information on projects, replaced and French, with equivalent terms in 16 additional languages.
and withdrawn publications. Also known as the International Electrotechnical Vocabulary

(IEV) online.
IEC Just Published - webstore.iec.ch/justpublished
Stay up to date on all new IEC publications. Just Published IEC Glossary - std.iec.ch/glossary
details all new publications released. Available online and 67 000 electrotechnical terminology entries in English and
once a month by email. French extracted from the Terms and Definitions clause of
IEC publications issued since 2002. Some entries have been
IEC Customer Service Centre - webstore.iec.ch/csc collected from earlier publications of IEC TC 37, 77, 86 and
If you wish to give us your feedback on this publication or CISPR.

need further assistance, please contact the Customer Service

Centre: [e-mail].
IEC TR 61244-4 ®
Edition 1.0 2019-09
TECHNICAL
REPORT
Determination of long-term radiation ageing in polymers –

Part 4: Effects of different temperatures and dose rates under radiation

conditions
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 17.240; 29.035.01 ISBN 978-2-8322-7429-3

– 2 – IEC TR 61244-4:2019 © IEC 2019
CONTENTS
FOREWORD . 3
INTRODUCTION . 5
1 Scope . 6
2 Normative references . 6
3 Terms, definitions and abbreviated terms . 6
3.1 Terms and definitions . 6
3.2 Abbreviated terms . 7
4 Radiation induced degradation mechanisms at standard ambient conditions . 8
4.1 General conventions . 8
4.2 Effect of presence of oxygen . 9
4.3 Effect of dose-rate effect-1: Physical aspects . 9
4.4 Effect of dose-rate-2: Chemical aspects . 10
4.5 Research on degradation mechanism . 10
4.6 Experiences and acceleration factors . 11
4.7 Low dose-rate tests and LOCA survivability . 11
4.8 Effect of LOCA test environment . 11
4.9 Order effects, synergistic effects, and antagonistic effects . 12
4.10 Sequential test conditions equivalent to simultaneous methods. 12
4.11 Studies after TMI and later . 13
4.12 Arrhenius law and limitations . 13
4.13 Slow degradation behaviour observed in service-aged cables . 16
4.14 Inverse temperature effects . 17
4.15 Role of antioxidants . 17
4.16 Other thermal and radiation environment degradation characteristics . 18
5 Accelerated ageing test methods . 18
5.1 Sequential ageing test . 18
5.1.1 General . 18
5.1.2 Sequence of testing and synergistic effects . 19
5.1.3 Guidance on test sequences . 20
5.1.4 Assessment of accelerated ageing. 20
5.2 Simultaneous ageing test . 21
6 Conclusion . 22
Bibliography . 23

Table 1 – Dose rate conditions which do not cause inhomogeneous degradation . 10
Table 2 – E value according to materials, manufacturers, and grades . 14
a
Table 3 – Changes in various properties due to inverse temperature and annealing
recovery effects, investigated by several instrumental analyses [111]. . 17
Table 4 – Typical standard acceleration ageing sequence for qualification . 19
Table 5 – More recent standard acceleration ageing sequence for qualification . 19

INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
DETERMINATION OF LONG-TERM RADIATION AGEING IN POLYMERS –

Part 4: Effects of different temperatures
and dose rates under radiation conditions

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
Committees in that sense. While all reasonable efforts are made to ensure that the technical content of IEC
Publications is accurate, IEC cannot be held responsible for the way in which they are used or for any
misinterpretation by any end user.
4) In order to promote international uniformity, IEC National Committees undertake to apply IEC Publications
transparently to the maximum extent possible in their national and regional publications. Any divergence
between any IEC Publication and the corresponding national or regional publication shall be clearly indicated in
the latter.
5) IEC itself does not provide any attestation of conformity. Independent certification bodies provide conformity
assessment services and, in some areas, access to IEC marks of conformity. IEC is not responsible for any
services carried out by independent certification bodies.
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
members of its technical committees and IEC National Committees for any personal injury, property damage or
other damage of any nature whatsoever, whether direct or indirect, or for costs (including legal fees) and
expenses arising out of the publication, use of, or reliance upon, this IEC Publication or any other IEC
Publications.
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.
The main task of IEC technical committees is to prepare International Standards. However, a
technical committee may propose the publication of a Technical Report when it has collected
data of a different kind from that which is normally published as an International Standard, for
example "state of the art".
IEC TR 61244-4, which is a Technical Report, has been prepared by IEC technical committee
112: Evaluation and qualification of electrical insulating materials and systems.
The text of this Technical Report is based on the following documents:
Draft TR Report on voting
112/442/DTR 112/446/RVDTR
Full information on the voting for the approval of this Technical Report can be found in the
report on voting indicated in the above table.

– 4 – IEC TR 61244-4:2019 © IEC 2019
This document has been drafted in accordance with the ISO/IEC Directives, Part 2.
A list of all parts in the IEC 61244 series, published under the general title Determination of
long-term radiation ageing in polymers, can be found on the IEC website.
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.
A bilingual version of this publication may be issued at a later date.

INTRODUCTION
IEC 60216 (all parts) and IEC 60544 (all parts) give reference and guidance for managing
accelerated thermal and radiological ageing steps for type testing procedures applicable to
electrical insulating materials. The actual application of electrical equipment usually requires
the consideration of effects which are a consequence of simultaneous occurrence of
temperature and radiation at varying intensities.
The CIGRE WG D1.42 study presents degradation data in particular with respect to cable and
wire insulation materials gathered from tests where thermal and radiation loads were applied
simultaneously. Even if there is a broad range of materials available from the industry, only
insulation materials commonly used were selected for this study. These materials are
crosslinked polyethylene (XLPE), ethylene-propylene-rubber (EPR), silicon-rubber (SIR) and
polyvinylchloride (PVC). Using these test data, power plant operators were in the position to
meet requirements defined by regulatory bodies in the frame of ‘long term operation
application’, showing that most insulation materials which have been in operation for 30 to 40
years were in good condition. Furthermore, material samples were collected from real
positions and test results were compared with reference samples, unaged as well as
artificially aged.
The main objective of the industry is to yield reliable values of the residual lifetime of the
insulation materials and linked pieces of equipment made up of these materials. However
more research is necessary as the in-service degradation of insulating materials appears to
be deviating from estimation based on accelerated ageing tests. For a better determination of
the degradation processes of insulation materials it is important to gain a wider knowledge on
material degradation and linked synergistic e
...