BS IEC 60988-2009 Nuclear power plants - Instrumentation important to safety - Acoustic monitoring systems for detection of loose parts Characteristics design criteria and operatio.pdf

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1、raising standards worldwideNO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAWBSI British StandardsWB9423_BSI_StandardColCov_noK_AW:BSI FRONT COVERS 5/9/08 12:55 Page 1Nuclear power plants Instrumentation important tosafety Acoustic monitoringsystems for detection of looseparts: C

2、haracteristics, designcriteria and operational proceduresBS IEC 60988:2009National forewordThis British Standard is the UK implementation of IEC 60988:2009.The UK participation in its preparation was entrusted to Technical CommitteeNCE/8, Reactor instrumentation.A list of organizations represented o

3、n this committee can be obtained onrequest to its secretary.This publication does not purport to include all the necessary provisions of acontract. Users are responsible for its correct application. BSI 2009ISBN 978 0 580 55527 5ICS 27.120.20Compliance with a British Standard cannot confer immunity

4、fromlegal obligations.This British Standard was published under the authority of the StandardsPolicy and Strategy Committee on 30 September 2009Amendments issued since publicationAmd. No. Date Text affectedBRITISH STANDARDBS IEC 60988:2009IEC 60988Edition 2.0 2009-08INTERNATIONAL STANDARD NORME INTE

5、RNATIONALENuclear power plants Instrumentation important to safety Acoustic monitoring systems for detection of loose parts: characteristics, design criteria and operational procedures Centrales nuclaires de puissance Instrumentation importante pour la sret Systmes de surveillance acoustique pour la

6、 dtection des corps errants: caractristiques, critres de conception et procdures dexploitation INTERNATIONAL ELECTROTECHNICAL COMMISSION COMMISSION ELECTROTECHNIQUE INTERNATIONALE WICS 27.120.20 PRICE CODECODE PRIXISBN 2-8318-1057-4 Registered trademark of the International Electrotechnical Commissi

7、on Marque dpose de la Commission Electrotechnique Internationale BS IEC 60988:2009 2 60988 IEC:2009 CONTENTS INTRODUCTION.6 1 Scope.8 2 Normative references .8 3 Terms and definitions .8 4 Purpose and description of loose parts detection10 4.1 General .10 4.2 System definition.10 4.3 System outline.

8、11 5 System requirements11 5.1 Basic structure and design criteria.11 5.2 Signal acquisition 13 5.2.1 Selection and installation of the sound sensors .13 5.2.2 Preamplifiers .14 5.3 Signal processing14 5.3.1 General .14 5.3.2 Band-pass filters .14 5.3.3 External output signal14 5.3.4 Amplifier14 5.4

9、 Signal storage and signal display 15 5.4.1 Background noise monitoring.15 5.4.2 Digitisation and storage .15 5.4.3 Audio unit 16 5.4.4 Information display 16 5.5 Signal monitoring 17 5.5.1 General .17 5.5.2 Alarm level monitor17 5.5.3 Logic element18 5.6 Calibration.19 5.6.1 General .19 5.6.2 Mecha

10、nical functional test unit.19 5.6.3 Electrical calibration unit .19 6 Initial start-up and operation.20 6.1 System testing before initial start-up of coolant circulating pump.20 6.2 Preliminary surveillance without alarm levels.20 6.3 Adapting the system to the plant requirements 20 7 Surveillance p

11、rogramme.21 7.1 General .21 7.2 Reference recordings 21 7.3 Measurements during operation 22 7.3.1 Preliminary surveillance.22 7.3.2 Surveillance.22 7.4 Actions following an alarm.23 7.5 Periodic testing of the system23 7.5.1 General .23 7.5.2 Functional tests .23 BS IEC 60988:200960988 IEC:2009 3 7

12、.5.3 Electrical system test.24 7.5.4 Test impacts24 8 Documentation .25 Annex A (informative) Description of loose parts detection with typical sound traces .26 Annex B (informative) Description of detailed functions of each block of the functional block diagram .31 Annex C (informative) Examples of

13、 digital loose parts monitoring systems.32 Annex D (informative) Comments on evaluation.34 Bibliography37 Figure 1 Functional block diagram of a loose parts monitoring system .12 Figure A.1a Typical signals of stationary background noise of a PWR27 Figure A.1b Typical signals of stationary backgroun

14、d noise of a BWR27 Figure A.1 Typical signals27 Figure A.2 Signals with bursts caused by an operation-related single sound event (control rod drive) .28 Figure A.3 Signals with bursts caused by an impact of a loose part (pin of upper core support plate) .28 Figure A.4a Signals with bursts, caused by

15、 a test impact at a BWR .29 Figure A.4b Localisation at a BWR.29 Figure A.4 BWR.29 Figure A.5a Signals with burst, caused by a test impact at a PWR .30 Figure A.5b Localisation at a PWR.30 Figure A.5 PWR.30 Figure C.1 Block schematic diagram of a digital loose parts monitoring system32 Figure C.2 Bl

16、ock schematic diagram of a digital loose parts monitoring system.33 Figure D.1 Auto power spectral density and amplitude distribution of a measurement signal with electrical interference 35 Figure D.2 Burst with corresponding frequency spectrum.35 Figure D.3 Trend and distribution of channel-selecti

17、ve burst-amplitudes 36 Figure D.4 Burst signals with determination of delay differences36 BS IEC 60988:2009 6 60988 IEC:2009 INTRODUCTION a) Technical background, main issues and organisation of this Standard This International Standard addresses the issues specific to acoustic monitoring systems fo

18、r loose parts detection. It describes the principles, the characteristics and the test methods for those systems. It is intended that this Standard 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 s

19、tandard series IEC 60988 is the third level SC 45A document related to acoustic monitoring systems for loose parts detection used in power 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

20、 application of this Standard It is important to note that this Standard establishes no additional functional requirements for safety systems. 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-l

21、evel document of the IEC SC 45A standard series is IEC 61513. It provides general requirements for I or on a remote site at a national level. This implies that the transfer of all of the necessary data to the experts is always fully efficient. BS IEC 60988:200960988 IEC:2009 11 The triggering of an

22、alarm sent to the control room may be based on signals exceeding a threshold by either: the burst amplitude of a single sound event. This makes it possible to record and analyse the signals event by event, or the rate at which transients are detected. This implies continuously recording the signals.

23、 The diagnosis is then made from an analysis including many single sound events. The monitoring of the state of the sensors may be done by a calibration test equipment for the measurement lines with impact hammer units on the primary circuit, or by in-depth monitoring and signal processing of the ba

24、ckground noise. When designing a new system a choice from the above-mentioned items should be made as a first step. According to the national regulation the system definition needs to be specified. 4.3 System outline Loose parts detection systems typically consist of a set of accelerometers mounted

25、on the reactor vessel, steam generators and coolant pump casings, with processing electronics to filter the sound signals from the sensors and monitor them for alarms. Recording facilities are provided, and operators generally listen to the sensor noise at regular intervals, and specifically after r

26、efuelling, due to the sensitivity and processing power of the human ear. A fuller description with typical sound traces is provided in Annex A. 5 System requirements 5.1 Basic structure and design criteria Generally the system has the following basic functions (see Figure 1). signal acquisition, sig

27、nal processing, signal storage and signal display, signal monitoring, calibration. Requirements for each basic function are described in the following subclauses. BS IEC 60988:2009 12 60988 IEC:2009 impactsCalibration Signal processing Structure Test impacts External signalprocessing Signal acquisit

28、ion Alarm level Operational information Signal storage and signal display Signal monitoring IEC 1511/09 Key 1 Sound sensor 8 Audio unit 2 Preamplifier 9 Alarm level monitor 3 Band-pass filter 10 Logic element 4 Decoupled signal outputs 11 Internal alarm unit 5 Amplifier 12 Interface to external alar

29、m unit 6 Indicator (display) 13 Calibration unit 7 Recording or storage NOTE 1 Control signals are not shown. NOTE 2 On-line calibration equipment and test impact units need not be permanently installed. NOTE 3 The monitoring system is an operational system whose function is not classified at a high

30、 category according to IEC 61513 and IEC 61226. Figure 1 Functional block diagram of a loose parts monitoring system The detailed functions of each block are described in informative Annex B and specific requirements are given in the following subclauses. The design and installation of the system (i

31、ncluding its detection sensitivity) shall be in accordance with national regulations relating to system instrumentation and control for the particular reactor plant. The system shall be designed using a frequency range consistent with detection algorithms that will ensure sufficient sensitivity of t

32、he system to detect a metallic loose part with a minimum of false alarms. Depending upon the particular detection algorithm the frequency range is typically between fa= 0,5 Hz to 1 kHz and fb= 10 kHz to 20 kHz, where faand fbrefer to the lower and upper 3 dB frequencies of the bandwidth of the pass

33、band. NOTE Processing up to fb= 20 kHz is very suitable. BS IEC 60988:200960988 IEC:2009 13 The differences in the transfer functions of one measuring chain from any other measuring chain, excluding the sound sensors, should not be greater than 1 dB when selecting identical cut-off frequencies of th

34、e band-pass filters. 5.2 Signal acquisition 5.2.1 Selection and installation of the sound sensors The recommended sound sensors are piezoelectric transducers. Sound sensors shall be selected to be able to withstand the ambient conditions (e.g. simultaneous exposure to high temperature and radiation

35、levels, splash water) prevailing at their point of installation. The sound sensors shall be mounted on the outer surface of the pressure-retaining boundary. All methods of attachment (e.g. screw, magnetic, clamping connections) which meet the requirements described in this standard may be used. All

36、sound sensors should have uniform response characteristics. The mounting locations shall be selected on the basis of the following: the sound sensors shall be positioned in the areas to be monitored. Monitoring areas are, e.g., the reactor pressure vessel bottom head and steam generator inlet water

37、box, the sound sensors should be mounted in accessible areas where conditions for sound transmission between the internal structures and the pressure-retaining boundary are particularly favourable (e.g. in the nozzle area of the pressurised water reactor, in the area of the core supports and in the

38、area of the dryer support ring in boiling water reactors), the sound sensors should be replaceable, the arrangement of the sound sensors shall not restrict accessibility for non-destructive examinations, and the sensor location should be selected so as to minimise dose rates to the equipment and per

39、sonnel conducting maintenance on the equipment. The number of sound sensors for each monitoring area is directly related to the function. If detection is required of a detached or loosened part only, then a single sound sensor is sufficient. To distinguish between detached and loosened parts, two so

40、und sensors may be adequate in many cases. When it is necessary to locate detached and loosened parts two dimensionally, at least three sound sensors are required (e.g. reactor pressure vessel surveillance). In case of defective and inaccessible sound sensors, new sound sensors may be installed in a

41、ccessible areas as a replacement, taking account of the information content of the signals in comparison to the dose exposure of the personnel conducting maintenance. NOTE It may be preferable to place at least two sensors in each monitoring area which avoids information loss in case of a defective

42、sensor. Further sound sensors may be necessary for the diagnosis of single sound events. The associated signals may be monitored separately. For installing the sound sensors, the mounting locations shall be prepared in accordance with the nature of the intended connection. The mounting surface for t

43、he sound sensors should be matched to the intended type of mounting. In addition, screw and clamping connections shall be protected against loosening, and magnets against slipping. Provision shall be made for the strain relief of the sensor cables. The installation sites for sensors should be agreed

44、 with the design and site installation engineers concerned with the vessels that are monitored and those concerned with their thermal insulation. Removable sections of insulation should be used to allow access to the sensors. BS IEC 60988:2009 14 60988 IEC:2009 5.2.2 Preamplifiers The signals receiv

45、ed from the sound sensors should be converted in preamplifiers (or impedance converters) in such a way that the transmission to the signal processing unit is as free from interference as possible. The design of the preamplifiers should take into account the ambient conditions which prevail at the po

46、int of installation. Electrical interference shall be minimized by suitable choice of cable type, routing and length, due consideration being given to installation and maintenance. These cables shall be designed to withstand the ambient conditions. The gain of the preamplifiers shall be adjusted to

47、the sensitivity of each sound sensor in such a way that all channels have nominally identical sensitivities within a tolerance of 10 %. NOTE Identical sensitivities of the channels within a tolerance of 10 % may also be achieved by adjustment of the gain of the processing unit. The upper cut-off fre

48、quency shall be selected in such a way that the adaptive resonant frequency is transmitted. 5.3 Signal processing 5.3.1 General The functions of the signal processing unit should be: to improve the ratio of signal strength to stationary background noise by means of band-pass filtering, to provide un

49、filtered signals for external processing, to process the signals so that they are suitable for signal storage, signal display and signal monitoring. These requirements may be fulfilled in various ways, provided that the design criteria of 5.1 are fulfilled. The signal processing unit normally consists of the modules included below. 5.3.2 Band-pass filters The band-pass filters shall have minimum characteristics of: filter steepness: 24 dB/oc