1、| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | BRITISH STANDARD BS IEC 61501:1998 ICS 27.
2、120.10 NO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAW Nuclear reactor instrumentation Wide range neutron fluence rate meter Mean square voltage methodThis British Standard, having been prepared under the direction of the Engineering Sector Committee, was published under the a
3、uthority of the Standards Committee and comes into effect on 15 July 2001 BSI 07-2001 ISBN 0 580 35396 6 BS IEC 61501:1998 Amendments issued since publication Amd. No. Date Comments National foreword This British Standard reproduces verbatim IEC 61501:1998 and implements it as the UK national standa
4、rd. The UK participation in its preparation was entrusted to Technical Committee NCE/8, Reactor instrumentation, which has the responsibility to: aid enquirers to understand the text; present to the responsible international/European committee any enquiries on the interpretation, or proposals for ch
5、ange, and keep the UK interests informed; monitor related international and European developments and promulgate them in the UK. A list of organizations represented on this committee can be obtained on request to its secretary. From 1 January 1997, all IEC publications have the number 60000 added to
6、 the old number. For instance, IEC 27-1 has been renumbered as IEC 60027-1. For a period of time during the change over from one numbering system to the other, publications may contain identifiers from both systems. Cross-references The British Standards which implement international or European pub
7、lications referred to in this document may be found in the BSI Standards Catalogue under the section entitled “International Standards Correspondence Index”, or by using the “Find” facility of the BSI Standards Electronic Catalogue. A British Standard does not purport to include all the necessary pr
8、ovisions of a contract. Users of British Standards are responsible for their correct application. Compliance with a British Standard does not of itself confer immunity from legal obligations. Summary of pages This document comprises a front cover, an inside front cover, the IEC title page, pages 2 t
9、o 40, an inside back cover and a back cover. The BSI copyright notice displayed throughout this document indicates when the document was last issued.1egaP BSIEC61501:1998 BSI 07-2001 CONTENTS Page FOREWORD. 3 INTRODUCTION . 4 Clause 1 Scope. 5 2 Normative references 5 3 Definitions. 6 4 Abbreviation
10、s 7 5 Principle of the mean square voltage method 7 6 Implementation of the mean square voltage method 8 6.1 Linear analogue method: quadratic amplifier 8 6.2 Logarithmic analogue method: logarithmic amplifier 9 6.3 Digital method: digital mean square processor . 9 7 Structure of a wide range channe
11、l . 10 7.1 Single-detector WRC. 11 7.2 Double-detector WRC 12 8 Technology of WRC 12 8.1 Analogue wide range channel. 13 8.2 Digital wide range channel . 13 9 Test conditions and test generators. 14 9.1 Environmental test conditions. 14 9.2 Test equipment 14 10 Characteristics and test methods for p
12、reamplifiers. 15 10.1 Characteristics of the preamplifier 15 10.2 Test methods for the preamplifier. 16 11 Characteristics and test methods for quadratic amplifiers 20 11.1 Characteristics of the quadratic amplifier 20 11.2 Test methods for the quadratic amplifier. 20 12 Characteristics and test met
13、hods for logarithmic amplifiers 26 12.1 Characteristics of the logarithmic amplifier . 26 12.2 Test methods for the logarithmic amplifier 26 13 Characteristics and test methods for logarithmic summing amplifiers. 31 13.1 Characteristics of the summing amplifier 31 13.2 Test methods for the summing a
14、mplifier. 33 14 Characteristics and test methods for digital mean square processors (DMSP) . 35 14.1 Characteristics of the digital mean square processor 35 14.2 Test methods for the DMSP . 36 Annex A (informative) Applications of WCRs. 38 Bibliography 4 0 2egaP 8991:10516CEISBPage2 BSIEC61501:1998
15、BSI 07-2001 INTERNATIONAL ELECTROTECHNICAL COMMISSION _ NUCLEAR REACTOR INSTRUMENTATION WIDE RANGE NEUTRON FLUENCE RATE METER MEAN SQUARE VOLTAGE METHOD FOREWORD 1) The IEC (International Electrotechnical Commission) is a worldwide organization for standardization comprising all national electrotech
16、nical committees (IEC National Committees). The object of the 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, the IEC publishes International Standards. Their preparatio
17、n 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. The IEC collaborates closely wi
18、th the International Organization for Standardization (ISO) in accordance with conditions determined by agreement between the two organizations. 2) The formal decisions or agreements of the IEC on technical matters express, as nearly as possible, an international consensus of opinion on the relevant
19、 subjects since each technical committee has representation from all interested National Committees. 3) The documents produced have the form of recommendations for international use and are published in the form of standards, technical reports or guides and they are accepted by the National Committe
20、es in that sense. 4) In order to promote international unification, IEC National Committees undertake to apply IEC International Standards transparently to the maximum extent possible in their national and regional standards. Any divergence between the IEC Standard and the corresponding national or
21、regional standard shall be clearly indicated in the latter. 5) The IEC provides no marking procedure to indicate its approval and cannot be rendered responsible for any equipment declared to be in conformity with one of its standards. 6) Attention is drawn to the possibility that some of the element
22、s of this International Standard may be the subject of patent rights. The IEC shall not be held responsible for identifying any or all such patent rights. This International Standard IEC 61501 has been prepared by subcommittee 45A: Reactor instrumentation, of IEC technical committee 45: Nuclear inst
23、rumentation. The text of this standard is based on the following documents: FDIS Report on voting 45A/338/FDIS 45A/346/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. Annex A is for information only. 3egaP 8991:1
24、0516CEISBPage3 BSIEC61501:1998 BSI 07-2001 INTRODUCTION The response of a fission chamber to a neutron is to produce a pulse of electrical charge and by counting these pulses it is possible to measure the neutron fluence rate. At higher levels the rate of pulse generation increases to the point wher
25、e pulses merge (a phenomenon known as “pulse pile-up“) and the process of electronically counting the pulses becomes impracticable. An alternative approach to processing is to consider the piled-up pulses as a fluctuating d.c. signal. Using Campbells theory it can be shown that the mean square of th
26、e signal amplitude, measured over a fixed bandwidth, is proportional to the initial pulse rate. At low fluence rate levels the use of this approach is limited to 10 3to 10 4fissions per second by background noise in the electronics and in the fission chamber. The limit at high fluence rate levels is
27、 in the range 10 10to 10 11fissions per second because of non linearity caused by space charge effects. This is the most common application of the MSV method. The use of the mean square voltage (MSV) measurement technique in combination with pulse counting permits the design of a system capable of m
28、easuring a neutron fluence rate over a range of more than 11 decades using a single fission chamber with appropriate corrections. It is also possible to use two different detectors. 4egaP 8991:10516CEISBPage4 BSIEC61501:1998 BSI 07-2001 NUCLEAR REACTOR INSTRUMENTATION WIDE RANGE NEUTRON FLUENCE RATE
29、 METER MEAN SQUARE VOLTAGE METHOD 1 Scope This International Standard applies to instrument and measurement channels which generate a calculation of the mean square voltage (MSV) of a signal arising from a neutron detector, in order to extract from it information relating to the neutron fluence rate
30、 of a nuclear reactor. After calibration, this information can be used to derive the relative power and the time constant, for example expressed in terms of period, doubling time, decades per minute or percent per second. The method used to calculate the mean square voltage of the signal is also kno
31、wn as “fluctuation treatment“ or “the Campbell method“. Associated with other techniques of measurement, such as pulse rate counting or current measurement, the calculation of the mean square voltage allows the assembly of a series of wide range neutron fluence rate measurements for the simplificati
32、on of nuclear instrumentation systems in the control of nuclear reactors. This standard describes the principles, the terminology, the characteristics, the requirements and the testing methods related to instrumentation and measurement of the neutron fluence rate using MSV techniques for nuclear rea
33、ctor control. Typical examples of the application of the MSV techniques are given. 2 Normative references The following normative documents contain provisions which, through reference in this text, constitute provisions of this International Standard. At the time of publication, the editions indicat
34、ed were valid. All normative documents are subject to revision, and parties to agreements based on this International Standard are encouraged to investigate the possibility of applying the most recent editions of the normative documents indicated below. Members of IEC and ISO maintain registers of c
35、urrently valid International Standards. IEC 60050(101):1998, International Electrotechnical Vocabulary (IEV) Part 101: Mathematics IEC 60050(393):1996, International Electrotechnical Vocabulary (IEV) Chapter 393: Nuclear instrumentation: Physical phenomena and basic concepts IEC 60050(394):1995, Int
36、ernational Electrotechnical Vocabulary (IEV) Chapter 394: Nuclear instrumentation: Instruments IEC 60359:1987, Expression of the performance of electrical and electronic measuring equipment IEC 60527:1975, Direct current amplifiers; characteristics and test methods IEC 60650:1979, Analogue counting
37、ratemeters Characteristics and test methods IEC 60880:1986, Software for computers in the safety systems of nuclear power stations 5egaP 8991:10516CEISBPage5 BSIEC61501:1998 BSI 07-2001 3 Definitions For the purpose of this International Standard, the definitions given in IEC 60050(101), IEC 60050(3
38、93) and 60050(394), as well as the following apply. NOTE The principle of the method is based on the variations analysis of the output of a detector and amplifier channel. These variations have many origins: the pulses induced by the reactions of detection and the perturbations internal or external
39、to the channel. To ensure clarity in the document, the terms which characterize the origin of the signal are defined. Generally the term “noise“ refers to the signal variations linked to the perturbations. 3.1 fluctuations random variations of a physical quantity around its mean value NOTE In this s
40、tandard, “fluctuations” means the variations of the measured signal induced by ionizing phenomena inside the detector. These variations are produced by the gamma radiation, by the alpha emission of the sensitive coating or by the neutron reactions induced in the coating. For the considered applicati
41、ons only, the fluctuations from neutron reactions are useful. 3.2 electronic noise variation of a signal produced by the thermal agitation of the components of the electronic circuits. It is an internal perturbation of the measuring channel. 3.3 system noise all variations of the signal with an orig
42、in external to the measuring channel 3.4 white noise random process whereby the power density spectrum is constant and independent of the frequency 3.5 Poisson process process defined according to the three following hypotheses: the number of events noted in a time interval T is independent of time
43、and independent of any events which have already occurred; the probability of having one event, and one only, in a time interval T is proportional to T when T 0; the probability of having more than one event in a time interval T tends towards 0 faster than T when T 0. The law of probability P is: P(
44、,) () ! e KT aT K K aT where K is the number of considered events; T is the time interval considered; a is the mean number of events. It occurs in all nuclear fission reactions. 6egaP 8991:10516CEISBPage6 BSIEC61501:1998 BSI 07-2001 3.6 pseudo-random signal periodic deterministic signal with spectra
45、l properties similar to those of Poisson processes. The pseudo-random signal provides a constant amplitude envelope at discrete frequencies within a certain frequency band. (The Poisson random signal tends to give a continuous spectrum.) 3.7 counting rate method signal processing method which applie
46、s to a signal having the form of separate pulses. The useful information representative of the neutron fluence rate is contained in the number of pulses per each unit of time (counting rate). 3.8 mean square voltage method signal processing method which applies to a random signal. The information re
47、presentative of the neutron fluence rate is contained in the mean square value of the a.c. part of the detector signal. NOTE This method and its application for neutron fluence rate measurement are presented in this standard. 3.9 wide range channel detection assembly using at the same time several m
48、easurement techniques such as counting rate, d.c. measurement, mean square voltage method 4 Abbreviations cps counts per second DMSP digital mean square processor DPM decades per minute EMC electromagnetic compatibility FP full power PPS percent per second LOCA loss of coolant accident MSV mean squa
49、re voltage nv neutron fluence rate unit. Notation for neutron cm 2 s 1 OPM octaves per minute r.m.s. root mean square S/I source/intermediate WRC wide range channel 5 Principle of the mean square voltage method The principle of the mean square voltage method is to process the signal coming from a neutron detector to estimate the mean voltage induced by the fluctuation. This voltage is proportional to the square root of the neutron fluence rate. For this type of measurement, a neutron detector,
