1、raising standards worldwideNO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAWBSI Standards PublicationNuclear power plants Instrumentation important to safety Thermocouples: characteristics and test methodsBS IEC 62651:2013National forewordThis British Standard is the UK implemen
2、tation of IEC 62651:2013.The UK participation in its preparation was entrusted to Technical CommitteeNCE/8, Reactor instrumentation.A list of organizations represented on this committee can be obtained onrequest to its secretary.This publication does not purport to include all the necessary provisio
3、ns of acontract. Users are responsible for its correct application. The British Standards Institution 2013Published by BSI Standards Limited 2013ISBN 978 0 580 75512 5ICS 27.120.20Compliance with a British Standard cannot confer immunity fromlegal obligations.This British Standard was published unde
4、r the authority of the StandardsPolicy and Strategy Committee on 31 May 2013.Amendments issued since publicationAmd. No. Date Text affectedBRITISH STANDARDBS IEC 62651:2013IEC 62651 Edition 1.0 2013-04 INTERNATIONAL STANDARD NORME INTERNATIONALE Nuclear power plants Instrumentation important to safe
5、ty Thermocouples: characteristics and test methods Centrales nuclaires de puissance Instrumentation importante pour la sret Thermocouples: caractristiques et mthodes dessai INTERNATIONAL ELECTROTECHNICAL COMMISSION COMMISSION ELECTROTECHNIQUE INTERNATIONALE V ICS 27.120.20 PRICE CODE CODE PRIX ISBN
6、978-2-83220-754-3 Registered trademark of the International Electrotechnical Commission Marque dpose de la Commission Electrotechnique Internationale Warning! Make sure that you obtained this publication from an authorized distributor. Attention! Veuillez vous assurer que vous avez obtenu cette publ
7、ication via un distributeur agr. BS IEC 62651:2013 2 62651 IEC:2013 CONTENTS FOREWORD . 4 INTRODUCTION . 6 1 Scope . 8 2 Normative references . 8 3 Terms and definitions . 8 4 List of abbreviations . 11 5 Principle of a thermocouple 11 5.1 General . 11 5.2 Types of thermocouples for nuclear applicat
8、ions . 13 5.2.1 General . 13 5.2.2 Type K . 13 5.2.3 Type T . 13 5.2.4 Type J . 13 5.2.5 Type N 13 5.2.6 Type E . 13 5.2.7 Type C 13 5.2.8 Noble metal thermocouples (Type S,R,B) 14 6 Technology of thermocouple assemblies 14 6.1 Thermocouple assembly 14 6.1.1 General . 14 6.1.2 Direct contact 15 6.1.
9、3 Direct immersion . 15 6.1.4 Thermowell mounted . 15 6.2 Performance 15 6.2.1 Accuracy . 15 6.2.2 Range of measurement . 15 6.2.3 Response time. 15 6.2.4 Reliability 15 6.3 Design and construction requirements . 16 6.3.1 General . 16 6.3.2 Reference junctions . 16 6.3.3 Construction principles 16 6
10、.3.4 Materials . 17 6.3.5 Insulation resistance (ungrounded thermocouple) 18 6.3.6 Interchangeability Replacement 18 6.4 Installation of thermocouple assembly . 18 6.4.1 Installation requirements . 18 6.4.2 Installation in a thermowell 19 6.4.3 Connections 19 6.5 Operational features of thermocouple
11、s 20 6.5.1 General considerations on the use of thermocouples . 20 6.5.2 Ambient conditions (normal and accident operations) 21 6.5.3 Metallurgical inhomogeneities 21 6.5.4 Corrosion. 21 6.5.5 Thermocouple stability . 21 6.5.6 Cold working phenomena 22 BS IEC 62651:201362651 IEC:2013 3 7 Tests 22 7.
12、1 General . 22 7.2 Performance tests and pre-production testing 22 7.2.1 General . 22 7.2.2 Calibration . 23 7.2.3 Response time. 23 7.2.4 Electrical insulation resistance tests 23 7.3 Qualification tests (type tests) . 23 7.3.1 General . 23 7.3.2 Repeatability (thermal shock) 24 7.3.3 Vibration 25
13、7.3.4 Steam test or high pressure hydraulic test . 25 7.3.5 Thermal cycling . 26 7.3.6 Harsh environmental conditions qualification . 26 7.4 Production tests 26 7.4.1 Manufacturing factors 26 7.4.2 Examination. 27 7.4.3 Identification 28 8 Technical information required 28 Bibliography 30 Figure 1 S
14、chematic diagram of a thermocouple 11 Figure 2 Electrical structures of a thermocouple . 14 Figure 3 Installation of a thermocouple in a thermowell 19 Table 1 List of thermocouples and their use in an NPP 12 Table 2 Example of vibration test requirements 25 BS IEC 62651:2013 4 62651 IEC:2013 INTERNA
15、TIONAL ELECTROTECHNICAL COMMISSION _ NUCLEAR POWER PLANTS INSTRUMENTATION IMPORTANT TO SAFETY THERMOCOUPLES: CHARACTERISTICS AND TEST METHODS FOREWORD 1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising all national electrotechnical commi
16、ttees (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
17、 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
18、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 agreem
19、ents 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 an
20、d 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
21、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
22、 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
23、 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
24、 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 publicati
25、on. 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 p
26、atent rights. International Standard IEC 62651 has been prepared by subcommittee 45A: Instrumentation and control of nuclear facilities, of IEC technical committee 45: Nuclear instrumentation. The text of this standard is based on the following documents: FDIS Report on voting 45A/904/FDIS 45A/920/R
27、VD 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. BS IEC 62651:201362651 IEC:2013 5 The committee has decided that the contents of
28、 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. BS IEC 62651:2013 6 6
29、2651 IEC:2013 INTRODUCTION a) Technical background, main issues and organisation of the Standard This IEC standard specifically focuses on thermocouple characteristics and test methods.It is intended that the Standard be used by operators of NPPs (utilities), systems evaluators, designers and by lic
30、ensors. b) Situation of the current Standard in the structure of the IEC SC 45A standard series IEC 62651 is the third level SC 45A document tackling the generic issue of design and qualification of thermocouples. It provides the technical background to the nature and use of thermocouples. It provid
31、es information on the choice of thermocouple type in relation to the nuclear power applications of concern. It describes the method of use of thermocouples in nuclear reactors. It gives detailed type test and manufacturing test requirements. IEC 62651 is to be read in association with IEC 60737 whic
32、h is the appropriate IEC SC 45A document which provides guidance on temperature sensors for reactor applications in general, and with IEC 60780 for equipment qualification. Other IEC standards of general application to thermocouples are given in the normative references of clause 2, and IAEA documen
33、ts and background information are referenced in the bibliography. 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
34、 no additional functional requirements for safety systems. Aspects for which special recommendations have been provided in this Standard are: the types of thermocouple suitable for nuclear reactor applications; the normal mounting arrangements; the use of hot or cold reference junctions and of compe
35、nsating cable; the mechanical and metallurgical aspects to be considered; the use and types of cold-end seals; installation; testing. 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. d) D
36、escription 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 BS IEC 62651:201362651 IEC:2013 15 direct imme
37、rsion; protected in a metallic support (thermowell) . 6.1.2 Direct contact The end of the thermocouple is welded or fixed on the metallic surface of the component. This is for example the typical arrangement for the incore thermocouple for the measurement of in-core temperature on the surface of the
38、 fuel element. 6.1.3 Direct immersion The thermocouple is in direct contact with the fluid of which the temperature is measured. 6.1.4 Thermowell mounted In the case of the measurement of the temperature of a fluid in a circuit, the thermocouple is generally inserted in a protective support called t
39、he thermowell. The use of a thermowell makes any replacement of the thermocouple easier. The mechanical contact of the end of the thermocouple with the envelope of the thermowell is important regarding the accuracy and the response time. 6.2 Performance 6.2.1 Accuracy The accuracy of a thermocouple
40、depends on the characteristics of the materials themselves and the accuracy of the cold junction temperature measurement. IEC 60584-2 specifies the amount by which the measurements may deviate from ideal behaviour for each type of thermocouple. Three classes of tolerance are defined in Table 1 of IE
41、C 60584-2:1982. The class of tolerance of a thermocouple depends on the manufacturing process. 6.2.2 Range of measurement The range of measurement is given by the type of the thermocouple as indicated above. The range differs according to the class of tolerance as indicated in IEC 60584-2. 6.2.3 Res
42、ponse time The response time of a thermocouple assembly depends on its structure including the thermowell. The response time of a thermocouple depends on the diameter of the wires, the mass of materials around the junction and its efficiency in transferring heat from its outer surfaces to the wire s
43、ensing element. A thermocouple can be shaped in order to reduce the thermal inertia and to shorten the response time. For NPP applications, the response time requirement shall be specified according to the functions to be performed. 6.2.4 Reliability The reliability requirement of thermocouples used
44、 for safety functions are defined from reliability requirements of the safety system. Experience of carefully manufactured thermocouples provided with high Quality Assurance and Quality Control requirements for NPP applications is that their reliability is high. Thermocouples operated in safety syst
45、ems should have their design lives defined. For thermocouples whose design life is less than the BS IEC 62651:2013 16 62651 IEC:2013 design life of the NPP or the safety system, then arrangement shall be made for these thermocouples to be replaced or re-assessed before their design life is reached.
46、6.3 Design and construction requirements 6.3.1 General The thermocouple and its associated devices shall meet the requirements described in this standard and in IEC 60737. Safety or other requirements for the application shall be determined according to national and international requirements and pr
47、actice, including IEC 61513. 6.3.2 Reference junctions A thermocouple is a differential device giving an electric signal related to the difference of temperature between the hot junction (to be measured) and the cold junction (reference). The cold junction is typically not kept at a known temperatur
48、e but rather the temperature is measured at the cold junction and this measurement is used to perform the cold junction temperature compensation to obtain the actual process temperature at the measurement junction. 6.3.3 Construction principles Thermocouples can be supplied in different internal con
49、structions, which depend on the manufacture, qualification requirements, and applications. For thermocouples being used in an NPP, the design and structure of the thermocouple should consider the environmental conditions in which the sensor is being used under normal operating and under design basis accident conditions, as well as the qualification tests specified by the user. The use of a flexible mineral-insulated cable between the thermocouple and the conn
