DIN 25475-2-2009 Nuclear facilities - Operational monitoring - Part 2 Vibration monitoring for early detection of changes in the vibrational behavior of the primary coolant circuit.pdf

1、May 2009DEUTSCHE NORM Normenausschuss Materialprfung (NMP) im DINDIN-SprachendienstEnglish price group 22No part of this translation may be reproduced without prior permission ofDIN Deutsches Institut fr Normung e. V., Berlin. Beuth Verlag GmbH, 10772 Berlin, Germany,has the exclusive right of sale

2、for German Standards (DIN-Normen).ICS 27.120.20!$a(M“1620542www.din.deDDIN 25475-2Nuclear facilities Operational monitoring Part 2: Vibration monitoring for early detection of changes in thevibrational behavio r of the primary coolant circuit in pressurized water reactorsEnglish translation of DIN 2

3、5475-2:2009-05Kerntechnische Anlagen Betriebsberwachung Teil 2: Schwingungsberwachung zur frhzeitigen Erkennung von nderungen imSchwingungsverhalten des Primrkreises von DruckwasserreaktorenEnglische bersetzung von DIN 25475-2:2009-05Installations nuclaires Surveillance en exploitation Partie 2: Sur

4、veillance des vibrations en vue de la dtection prcoce de modifications ducomportement vibratoire du circuit primaire de racteurs eau sous pressionTraduction anglaise de DIN 25475-2:2009-05SupersedesDIN 25475-2:2001-08www.beuth.deDocument comprises pages5807.10u DIN 25475-2:2009-05 2 A comma is used

5、as the decimal marker. Contents Page Foreword3 1 Scope 3 2 Normative references3 3 Terms and definitions .4 4 Description of the monitoring technology4 5 Requirements of the vibration monitoring system 7 5.1 Basic structure and interpretation criteria7 5.2 Data acquisition .9 5.2.1 General9 5.2.2 Se

6、lecting locations and installing the transducers and cables9 5.2.3 Example of a data acquisition 12 5.3 Signal conditioning .18 5.4 Signal analysis.19 5.5 Signal presentation .19 5.5.1 Display unit 19 5.5.2 Recording .19 5.6 Calibration 19 5.6.1 General19 5.6.2 Calibration unit 20 6 Commissioning20

7、6.1 General20 6.2 System checks.20 6.3 Measurements during commissioning of the reactor20 7 Performance of monitoring 21 7.1 General21 7.2 Prerequisites 21 7.3 Measurements22 7.3.1 General22 7.3.2 Reference measurements.22 7.3.3 Operational measurements 23 7.3.4 Identification 23 7.4 Monitoring 23 7

8、.4.1 Selecting a comparative measurement.23 7.4.2 Determination and evaluation of changes 24 7.5 Test of the monitoring system .28 7.5.1 General28 7.5.2 Test during fuel outage of the plant 29 7.5.3 Test during operation of the reactor29 8 Documentation.29 Annex A (informative) Vibration monitoring,

9、 Example 1.31 A.1 General31 A.2 Monitoring of the components of the primary circuit and reactor pressure vessel internals31 A.3 Frequency-selective monitoring of the shaft vibrations of the main coolant pumps 33 Annex B (informative) Vibration monitoring, Example 2.43 B.1 Monitoring the components o

10、f the primary circuit and reactor pressure vessel internals .43 B.2 Frequency-selective monitoring of shaft vibrations in the main coolant pumps.45 Annex C (informative) Example of signal trends of a fractured shaft .56 Bibliography58 DIN 25475-2:2009-05 3 Foreword This document has been prepared by

11、 NA 062-07-48 AA Betriebsberwachung Kerntechnik. Requirements with regard to the vibration monitoring system, its commissioning, the monitoring process, and documentation are specified in order to detect changes in the vibrational behaviour of the components of the primary circuit, the reactor press

12、ure vessel internals, and the main coolant pump shafts at an early enough stage so that there is sufficient time to analyze the changes in vibration and thus identify any imminent defects or damage and ensure aimed inspections. Based on KTA 3201.4, the standard is titled “Operational monitoring”. DI

13、N 25475 Nuclear facilities Operational monitoring comprises the following: Part 1: Monitoring of structure-borne sound for loose parts detection Part 2: Vibration monitoring for early detection of changes in the vibrational behaviour of the primary coolant circuit in pressurized water reactors Annex

14、es A, B and C are informative. Amendments This standard differs from DIN 25475-2:2001-08 as follows: a) Monitoring of main coolant pump shafts has been added; b) Modifications have been made as a result of operational experience; c) The definition of terms has been modified; d) Figures have been mod

15、ified; e) Annexes A and B have been modified, Annex C has been added. Previous editions DIN 25475-2: 2001-08 1 Scope This standard applies to procedures for early detection of changes in the vibration of the components of the primary circuit, the reactor pressure vessel internals, and main coolant p

16、ump shafts of pressurized water reactors. The monitoring system used in this respect is an operational facility that does not require a layout in accordance with KTA 3501. This standard shall not be applied to procedures for monitoring maximum shaft deflections of main coolant pumps. For details reg

17、arding maximum shaft deflections see DIN ISO 7919-1 and VDI 2059 Part 5. 2 Normative references The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the reference

18、d document (including any amendments) applies. DIN 25404:1991-01, Nuclear technology Symbols KTA 3204, Reactor pressure vessel internals KTA 3501, Reactor protection systems and monitoring facilities of the safety system DIN 25475-2:2009-05 4 3 Terms and definitions For the purposes of this document

19、, the following terms and definitions apply. 3.1 attention thresholds values that shall be established specifically in respect to the feature to be monitored and, if exceeded, require additional measures 3.2 peak identifiable part of the curve in a characteristic function that is characterized by a

20、local maximum and a definite width 3.3 frequency band frequency range that is defined by an upper and lower frequency 3.4 magnitude value of the auto power density spectrum relating to a frequency 3.5 resonance frequencies natural frequencies of components of the primary circuit modified by damping

21、and coupling 3.6 type of vibration time- and location-based vibration form of a component relating to the respective resonance frequency 4 Description of the monitoring technology The vibration monitoring system is used to detect changes in the vibration of reactor pressure vessel internals, additio

22、nal primary circuit components and main coolant pump shafts at an early stage. The parameters decisive for the vibration are masses, spring constants, dampings, excitation forces, gaps, and stops. The vibration behaviour is primarily recorded by transducers for the measurement of mechanical vibratio

23、n on the outside of the pressure retaining boundary, of the neutron flux noise, of pressure fluctuation, and of main coolant pump shaft vibration. These measurands provide information that are either meaningful by themselves, partly superimpose each other, or complement each other. The basic connect

24、ions of vibration excitation and available measurands as well as any information derived from them are outlined in Figure 1. DIN 25475-2:2009-05 5 Figure 1 Basic vibration-related connections at the primary circuit DIN 25475-2:2009-05 6 Figure 2 Examples of signals in the time domain and correspondi

25、ng auto power density spectra DIN 25475-2:2009-05 7 From a structure dynamics perspective, the components of the primary circuit form a vibratory coupled multiple mass system. In the following text reference is made to monitored components and corresponding peaks for simplification, since basically

26、the whole system is affected via the coupling. Depending on the degree of coupling, changes in the vibration of a component may also affect the vibration of other components (and thus the corresponding peaks). Hence, the signals of the transducers in the vibration monitoring system always comprise i

27、nformation regarding the vibration of several components. The vibration can be defined by way of characteristic functions and parameters. When operated properly, reference measurements are performed aiming at determining reference functions, reference parameters, and their values (reference values)

28、of the signals. These reference measurements are completed for the first time after initial operation of the reactor system (zero reference measurement) and, afterwards, only on certain occasions. During subsequent operation additional measurements (operational measurements) are performed. In order

29、to detect changes in vibration, the characteristic functions and parameters of these operational measurements are, on principle, compared to the applicable reference functions and reference parameters. The parameters are derived from the signals that are presented by means of Fourier transformation

30、within the frequency range. When monitoring the components of the primary circuit and the reactor pressure vessel internals, auto power density spectra are normally used as characteristic functions. Within these ranges, the vibration characteristics of the monitored components are displayed as peaks

31、. Hence, changes in the peaks can be directly attributed to changes in the vibration. Figure 2 shows signal trends and auto power density spectra of the measured system responses outlined in Figure 1, within the frequency range of 0 Hz to 110 Hz. In order to detect fractured shafts, not only the max

32、imum stroke of the pump shaft is determined but also in addition the shaft vibration portions with harmonized rotation frequency. In this selected frequency monitoring process, the magnitudes or effective values of the shaft vibration portions with harmonized rotation frequency are monitored. On the

33、 one hand, this analysis of the shaft vibration portions with harmonized rotation frequency is to ensure early detection of fractured shafts and, on the other hand, to obtain diagnosis information relating to the changes in the maximum stroke. Significant changes might either be attributed to known

34、long-term activities (e.g. in respect to the growth of fuel elements) or might indicate that there is an imminent defect or damage (e.g. deterioration of springs, loose connections, fractured shafts). In the informative Annexes A and B, two sample systems are described that use this IT-based monitor

35、ing technology. 5 Requirements for the vibration monitoring system 5.1 Basic structure and interpretation criteria The following functions shall be realized for the measurands used in the system: data acquisition; signal conditioning; signal analysis; DIN 25475-2:2009-05 8 signal presentation; calib

36、ration. Not all of these function requirements need to be met within the vibration monitoring system in respect to measurands from operational instrumentation (e.g. neutron flux measuring system, shaft vibration), if they have already been met elsewhere. The basic structure of the vibration monitori

37、ng system is shown in Figure 3. Key 1 Transducer 5 Analysis unit 2 Impedance converter 6 Displaying, registration and storing unit 3 Amplifier, filter 7 Calibration device 4 Non-reactive decoupling (e.g. isolating buffer) Figure 3 Block diagram of a vibration monitoring system Special transducers ca

38、n be used for data acquisition (1) (transducers, relative transducers, dynamic pressure sensors). Depending on the transducer, different sets of components (2) and (3) are used for conditioning of the signals (e.g. charge amplifier, carrier frequency amplifier). DIN 25475-2:2009-05 9 The signals of

39、the operational instrumentation (e.g. neutron flux measuring system, shaft vibration) shall be decoupled for the vibration monitoring system in a wideband and non-reactive manner (e.g. via an isolating amplifier (4). An analysis unit is required to further process the signals (5). In addition to ana

40、lyzing the signals in the time domain (maximum amplitudes), this unit shall analyze the signals in the frequency domain. It shall have at least two channels in order to be able to perform correlation analyses. In order to be able to externally process the signals, they shall be provided in a wideban

41、d manner via non-reactive decouplings (4). NOTE If the operation of the signal processing depends on the operation of the analysis unit, it is useful if the signals transmitted for external processes can also be provided in the event the analysis unit fails. The signals and characteristic functions

42、provided by the analysis unit shall be recordable for documentation (6). It shall be ensured that the measuring chains can be checked and reviewed. For this purpose, a calibration unit (7) is required. The system shall be designed in accordance with the general and plant-related requirements for ope

43、rational process control techniques that are applicable to the respective plant. To the extent that this is technically feasible and reasonable, the components of the vibration monitoring system shall be arranged in accessible rooms. The system shall be designed so that at least a frequency range of

44、 0,1 Hz to 200 Hz can be analyzed, the amplitude responses of measuring chains of the same type that can be calibrated together with the transducer do not deviate by more than 1,5 dB, the amplitude responses of measuring chains of the same type that cannot be calibrated together with the transducer

45、do not deviate by more than 1,0 dB. 5.2 Data acquisition 5.2.1 General Both special transducers and transducers of the operational instrumentation can be used for data acquisition. They shall be suitable in respect to type, sensitivity within the respective frequency range and location to provide me

46、asuring information that is sufficient for the monitoring process. Both direct and indirect measuring processes can be used to obtain the respective measuring information. In indirect measuring processes, the relation to the monitored measurands shall be known. Transducers and cables shall be select

47、ed so that they are suitable for the respective location at which they are used, i.e. they shall be heat- and radiation-resistant. In addition, they shall be installed in a splash-proof manner. 5.2.2 Selecting measuring locations and installing the transducers and cables The measuring locations and

48、number of transducers shall be selected so that meaningful information can be obtained to meet the objectives of the monitoring process. The state of knowledge required for this purpose is based on analytical and experimental experience or experience with similar plants. When selecting the locations

49、, one shall take into account that DIN 25475-2:2009-05 10 the transducers are arranged in such a way that access for the purpose of recurrent checks of the primary circuit is ensured, the local dose rate is as low as possible, the transducers can be installed and uninstalled quickly in order to minimize radiation exposure of staff (e.g. during repair work), the safety requirements of the pressurized boundary are met. The locations shall be prepared for the respective type of mounting of the vibration sensors. Due to