1、 g49g50g3g38g50g51g60g44g49g42g3g58g44g55g43g50g56g55g3g37g54g44g3g51g40g53g48g44g54g54g44g50g49g3g40g59g38g40g51g55g3g36g54g3g51g40g53g48g44g55g55g40g39g3g37g60g3g38g50g51g60g53g44g42g43g55g3g47g36g58Radiation detectors Characteristics and test methodsICS 27.120.20Nuclear power plants Instrumentati
2、on important to safety BRITISH STANDARDBS IEC 60515:2007BS IEC 60515:2007This British Standard was published under the authority of the Standards Policy and Strategy Committee on 30 April 2007 BSI 2007ISBN 978 0 580 50497 6Amendments issued since publicationAmd. No. Date Commentscontract. Users are
3、responsible for its correct application.Compliance with a British Standard cannot confer immunity from legal obligations.National forewordThis British Standard was published by BSI. It is the UK implementation of IEC 60515:2007. It supersedes BS 5548:1978 which is withdrawn. The UK participation in
4、its preparation was entrusted to Technical Committee NCE/8, Reactor instrumentation.A list of organizations represented on NCE/8 can be obtained on request to its secretary.This publication does not purport to include all the necessary provisions of a BS EN 60515:2007 IECINTERNATIONAL STANDARD 60515
5、Second edition2007-02Nuclear power plants Instrumentation important to safety Radiation detectors Characteristics and test methods Reference number CEI/IEC 60515:2007 BS EN 60515:2007 2 CONTENTS FOREWORD.4 INTRODUCTION.6 1 Scope 8 2 Normative references .8 3 Terms and definitions .9 4 Abbreviations
6、.12 5 Functions of an ex-core detection system.12 6 Neutron sensitive materials.13 7 Description of different types of detectors .14 7.1 General .14 7.2 Neutron sensitive proportional counters .14 7.3 Ionization chambers.16 8 More detailed factors which influence the use and testing of neutron detec
7、tors 19 8.1 Pulse mode neutron detectors19 8.2 Current mode neutron detectors.21 9 General principles for detector operation.24 9.1 Detection basis conditions .24 9.2 Detector operating conditions.24 9.3 Limits due to the detector 24 9.4 Limits due to the measuring channel 25 9.5 Limits due to surro
8、unding gamma radiation 25 10 Connectors and cables .26 11 Characteristics of detectors including their cables and connectors .26 11.1 General .26 11.2 Detector mechanical data 26 11.3 Detector electrical and nuclear data .27 11.4 Connector mechanical data28 11.5 Connector electrical characteristics2
9、8 11.6 Cable mechanical data 29 11.7 Cable electrical characteristics.29 12 Test methods general 29 13 Factory tests 29 13.1 General .29 13.2 List of typical factory tests .30 13.3 Mechanical tests31 13.4 Specific tests for fission counters (see Figure 4).31 13.5 Specific tests for proportional coun
10、ter tubes.33 13.6 Specific tests for compensated ionization chambers (see Figure 3).34 13.7 Specific tests for uncompensated neutron sensitive d.c. ionization chambers (see Figure 2)37 13.8 Specific tests for d.c. ionization chambers for gamma radiation 39 3 BS EN 60515:2007 13.9 Specific test for c
11、urrent fluctuation (Campbelling) fission chambers 39 14 Qualification tests.40 14.1 Principles 40 14.2 Test sequence on a detector40 14.3 Test for environmental conditions.40 14.4 Seismic tests.40 Bibliography .41 Figure 1 Neutron sensitive proportional counter15 Figure 2 Diagram of an uncompensated
12、 ionization chamber16 Figure 3 Diagram of a compensated ionization chamber .17 Figure 4 Diagram of a fission counter .18 Table 1 Important connector mechanical factors .28 BS EN 60515:2007 4 INTERNATIONAL ELECTROTECHNICAL COMMISSION _ NUCLEAR POWER PLANTS INSTRUMENTATION IMPORTANT TO SAFETY RADIATIO
13、N DETECTORS CHARACTERISTICS AND TEST METHODS 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 al
14、l 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 Publi
15、cation(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. IE
16、C 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 op
17、inion 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
18、 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 transparent
19、ly 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 provides no marking procedure to indicate its approval and cannot be rende
20、red 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 members of it
21、s 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 oth
22、er 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
23、 subject of patent rights. IEC shall not be held responsible for identifying any or all such patent rights. International Standard IEC 60515 has been prepared by subcommittee 45A: Instrumentation and control of nuclear facilities, of IEC technical committee 45: Nuclear instrumentation. This second e
24、dition cancels and replaces the first edition published in 1975. This edition constitutes a technical revision. The revision of the standard is intended to accomplish the following: To clarify the definitions by including the thermal neutron fluence rate and the total neutron fluence rate. To up-dat
25、e the reference to new standards published since the first issue, including IEC 61513 and IEC 61226. To update the units of radiations: nv unit of neutron fluence rate and Gy/h for gamma. 5 BS EN 60515:2007 The text of this standard is based on the following documents: FDIS Report on voting 45A/644/
26、FDIS 45A/647/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. The committee has decided that the contents of this publication wi
27、ll 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. BS EN 60515:2007 6 INTRODUCTION
28、a) Technical background, main issues and organisation of the standard This International Standard addresses the issues specific to neutron detectors used mainly for ex-core instrumentation systems. It describes the principles, the characteristics and the test methods for neutron detectors including:
29、 Proportional Counters, Ionization Chambers (compensated and non compensated) and fission chambers or fission counters. It is organized into clauses giving: the definitions; description of the different types of neutron detectors; analysis of the factors of influence; the operational conditions for
30、detectors; the factory tests; the qualification tests. b) Situation of the current standard in the structure of the IEC SC 45A standard series IEC 60515 is the third level IEC SC 45A document tackling the specific issue of characteristics and test methods related to radiation detectors used in power
31、 reactors. 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 There are no special recommendations or limitations regarding the application of this standard. d) Descriptio
32、n 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 Q2 is the mean square charge per event (neutron or gamm
33、a); N is the mean event rate (for neutrons, proportional to reactor power); K is a coefficient depending on the electronic system. From this, it can be seen that gamma rejection depends on the second order ratio of charge per event so that Campbelling mode chambers provide extremely good gamma rejec
34、tion. They reject leakage current in the same way and Campbelling can therefore be applied directly to the simple structure of the pulse fission chamber. Some systems use the same chamber, (operated in pulse mode at low power and in Campbell mode at medium and high powers) to cover the complete work
35、ing range of the reactor. Problems arise from the small amplitude of the signals and their subsequent vulnerability to EM interference. This mode is described more fully in IEC 61501. 8 More detailed factors which influence the use and testing of neutron detectors 8.1 Pulse mode neutron detectors 8.
36、1.1 General Pulse mode neutron detectors include the fission pulse ionization chamber, the BF3counter, the boron-lined counter and the helium-3 proportional counter. 8.1.2 Sensitivity in the linear range The sensitivity of a pulse mode neutron detector is usually measured in a neutron box (neutron i
37、rradiator) which produces a well thermalized and well defined neutron fluence rate. The sensitivity is determined by dividing the mean counting rate, excluding background, by the thermal neutron fluence rate (flux) at the detector. It is specified in units of counts per second per unit neutron fluen
38、ce rate (flux) (cps/nv). This sensitivity shall be measured with defined electrical characteristics in the detector and the measuring channel, and it shall be stated whether the neutron fluence rate is perturbed or unperturbed. BS EN 60515:2007 20 8.1.3 Range of measurement The theoretical range of
39、measurement of a pulse neutron detector is determined by its lower and upper limits. The theoretical lower limit for any counter is set by the required statistical accuracy from the determination of a low counting rate within pre-determined time constraints. Other limits on the pulse fission chamber
40、 arise from “alpha pile-up”, and, less often, from background due to spontaneous fissions. The true limit is usually deterioration of the counting characteristic caused either by amplifier noise (which becomes more dominant as the counting rate falls) or by the pile up of gamma events. The upper lim
41、it usually depends on the resolving time of the measuring channel, which is a function of the charge collection time and the electrical characteristics chosen. Other limits, usually important in proportional counters, are desaturation of the polarizing field and foreseeable detector life problems. 8
42、.1.4 Effect of gamma radiation The presence of significant gamma radiation is indicated by the degradation of the pulse spectrum, the bias plateau length and, in certain cases, by the reduction of the multiplication factor of proportional counters. 8.1.5 Operating temperature The structural material
43、s and the technology of manufacture determine the range of operating temperatures. At high temperature, the principal problems are to maintain satisfactory insulator performance and gas purity. 8.1.6 Burn-up and useful life The burn-up life depends on the consumption of the sensitive material. It is
44、 measured by the number of counted events or by the value of the neutron fluence corresponding to a specified quantity of sensitive material consumed. The typical burn-up life corresponds to 10 % depletion of the sensitive material. The useful life depends on the ambient conditions and influence qua
45、ntities, such as purity of gas and insulation characteristics. If storage conditions can affect the useful life of the detector, the requirements for storage shall be clearly defined. 8.1.7 Polarization voltage plateau curve The polarization voltage is defined by its polarity and magnitude. For puls
46、e counters, the polarization voltage is commonly a positive voltage applied to the collecting electrode. The negative side is applied to the case. For proportional counters, the multiplication factor depends on the value of the polarization voltage. The curve characterizing the relationship between
47、counting rate and polarization voltage is called the plateau curve. It is characterized by U1,1 and U0,9, the voltages at which the counting rate is 10 % above and 10 % below its value at the point of least slope. These parameters depend strongly on the discriminator level in a proportional counter
48、and may do so in a fission counter. 21 BS EN 60515:2007 Curves measured under agreed conditions shall be given by the manufacturer. 8.1.8 Discrimination threshold and discrimination curve The discrimination threshold is defined by the voltage amplitude of pulses after amplification. The curves chara
49、cterizing the relationship between counting rate and discrimination voltage is called the discrimination curve. This curve is limited at the low discriminator end by amplifier noise, alpha or gamma pile up and at the high end by the distribution of pulse height. It is characterized by V1,1 and V0,9, (or by A1,1 and A0,9, if the amplifier gain is varied instead of the discriminator voltage), the levels at which the counting rate is 10 % above and 10 % belo
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