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1、BRITISH STANDARD BS IEC 61505:1998 Nuclear reactor instrumentation Boiling water reactors (BWR) Stability monitoring ICS 27.120.10 Licensed Copy: sheffieldun sheffieldun, na, Sun Nov 26 11:42:18 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS IEC 61505:1998 This British Standard, having been prepared
2、under the direction of the Engineering Sector Committee, was published under the authority of the Standards Committee and comes into effect on 15 March 1999 BSI 05-1999 ISBN 0 580 32089 8 National foreword This British Standard reproduces verbatim IEC 61505:1998 and implements it as the UK national
3、standard. 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
4、for change, 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 ad
5、ded to 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 Europe
6、an publications 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 necess
7、ary provisions 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, pages i and ii, the CEI
8、 IEC title page, pages ii to iv, pages 1 to 27 and a back cover. This standard has been updated (see copyright date) and may have had amendments incorporated. This will be indicated in the amendment table on the inside front cover. Amendments issued since publication Amd. No.DateComments Licensed Co
9、py: sheffieldun sheffieldun, na, Sun Nov 26 11:42:18 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS IEC 61505:1998 BSI 05-1999i Contents Page National forewordInside front cover Text of CEI IEC 615051 Licensed Copy: sheffieldun sheffieldun, na, Sun Nov 26 11:42:18 GMT+00:00 2006, Uncontrolled Copy, (
10、c) BSI ii blank Licensed Copy: sheffieldun sheffieldun, na, Sun Nov 26 11:42:18 GMT+00:00 2006, Uncontrolled Copy, (c) BSI Licensed Copy: sheffieldun sheffieldun, na, Sun Nov 26 11:42:18 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS IEC 61505:1998 ii BSI 05-1999 Contents Page Introduction1 1Scope an
11、d object1 2Normative references2 3Terms and definitions2 4Abbreviations3 5Physics, measurement and analyses of instabilities4 5.1Physics of BWR core instabilities4 5.2Possible consequences of core instabilities5 5.3Measuring principles5 5.4Analysis methods6 6Functional requirements7 6.1On-line monit
12、oring8 6.2Off-line monitoring8 6.3Man-machine interface8 6.4Response time8 6.5Accuracy8 6.6Robustness8 7Safety classification8 8Technical requirements8 8.1Data acquisition system9 8.2Data processing and operator interface system9 8.3Hardware (HW)9 8.4Software (SW)9 9Verification and validation9 10Te
13、sting and maintenance9 11Qualification and documentation9 Annex A (informative) Automatic detection and suppression14 Annex B (informative) Examples of BWR power oscillation occurrences14 Annex C (informative) Examples of instability tests15 Annex D (informative) Instability prevention concept20 Ann
14、ex E (informative) Operating experience with stability monitoring23 Annex F (informative) Estimation of neutron noise characteristic function25 Annex G (informative) Estimation of phase difference26 Annex H (informative) Bibliography26 Figure 1 The four methods of coolant recirculation through the c
15、ore of a BWR10 Figure 2 Neutronic and thermal-hydraulic feedback mechanisms11 Figure 3 Feedback mechanisms for coupled neutronic-thermalhydraulic reactivity instability12 Figure 4 Example of BWR stability monitor13 Figure C.1 Vector plot showing LPRM signal variation in KRB-B16 Figure C.2 Vector plo
16、t showing LPRM signal variation in KRB-C17 Figure C.3 Vector plot (refer to instant A in Figure C.5)18 Figure C.4 Vector plot (refer to instant B in Figure C.5)19 Figure C.5 Advent of instability in a KWU-PL72 BWR20 Figure D.1 General form of the power-flow diagram21 Figure D.2 Power-flow diagram af
17、ter modification of setpoints22 Licensed Copy: sheffieldun sheffieldun, na, Sun Nov 26 11:42:18 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS IEC 61505:1998 BSI 05-1999iii Page Figure E.1 APRM signal in Forsmark 1 (1987), during operation with poor stability. The amplitude is 16 % peak-to-peak and t
18、he oscillation frequency is 0,5 Hz (figure from 13 of Annex H)24 Figure E.2 Auto power spectrum for APRM in Forsmark 1 (1987), under the high amplitude oscillations. The extra peak at 1 Hz is typical for the limit cycle operation (figure from 13 of Annex H)24 Figure E.3 Recursive calculation of DR a
19、s a function of time Data from Forsmark 1 (1987) (figure from 13 of Annex H)25 Table C.1 Summary of stability tests performed by KWU in its plants16 Licensed Copy: sheffieldun sheffieldun, na, Sun Nov 26 11:42:18 GMT+00:00 2006, Uncontrolled Copy, (c) BSI iv blank Licensed Copy: sheffieldun sheffiel
20、dun, na, Sun Nov 26 11:42:18 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS IEC 61505:1998 BSI 05-19991 Introduction Thermal hydraulic instability is a known phenomenon in conventional steam generators. Two phase flow oscillations in steam generators can result in local channel overheating. This phen
21、omenon and its impact on the design of steam generators is well documented. Under certain conditions boiling water reactors are also susceptible to such thermal hydraulic instabilities. The design of the reactor recirculation system has a large impact on the stability of the reactor system. Four dif
22、ferent BWR recirculation systems are used in modern BWRs: a) Internal pumps (Figure 1a) b) Jet pumps (Figure 1b) c) External pumps (Figure 1c) d) Natural recirculation (Figure 1d) Another critical factor in BWR stability is the neutronic feedback to the local fuel channel thermal-hydraulic perturbat
23、ion. The two feedback mechanisms, thermal-hydraulic and neutronic, are coupled in a BWR core and can, under certain conditions, generate oscillations in both core flow and thermal power. In addition, reactor instabilities can occur even when neither feedback mechanism alone is sufficient to generate
24、 instability. The physics of such BWR-instabilities are explained with some detail in clause 5. In order to identify flux oscillations characteristic of a thermal-hydraulic instability, a system that monitors neutron flux (APRM and LPRM signals) can be used. This system generates an output signal wh
25、ich can be used for automatic suppression functions. A short description of automatic detection and suppression is included in Annex A. A short account of examples of BWR instability incidents which have occurred during the last several years is given in Annex B. These events illustrate the importan
26、ce and the need for a standard on stability monitoring of BWR. A significant amount of information is now available relative to BWR stability from experience at operating BWRs. Special tests have been performed at numerous plants under controlled conditions to provide information on individual plant
27、 response during an instability and the portion of the operating domain most susceptible to oscillations for the operating conditions present at the time of the test. Examples of such special tests are given in Annex C. An instability prevention concept is described by the power flow diagram given i
28、n Annex D, which is used in Japan and Germany. In Annex E an account of operating experience with stability monitoring in different countries is given. Annex F gives an estimation of neutron noise characteristic functions, while the estimation of phase difference is described in Annex G. Annex H is
29、a bibliography. 1 Scope and object This International Standard applies to boiling water reactors (BWR) designed to ensure that thermal-hydraulic oscillations are either not possible, or can be reliably and readily detected and suppressed. Compliance with the criteria can be demonstrated by: a) preve
30、nting power oscillations; b) detecting and automatically suppressing power oscillations. Monitoring of the reactor stability state, which is the object of this standard, can support a) and b) by providing information on plant stability characteristics. Monitoring will detect the approach to, and occ
31、urrence of, oscillations. The purpose of this standard is to describe appropriate plant parameters for use in stability monitoring; define analysis methods for relating time-varying plant information to reactor stability figures of merit, such as the decay ratio; provide technical guidelines regardi
32、ng stability monitoring functional and performance requirements. The following items are not covered by this standard: a) control system instability; b) recommendations for implementing a particular solution or a combination of solutions; c) requirements for analytical methods associated with each m
33、ethod; d) requirements for manual operator and automatic actions necessary to suppress power oscillations or reduce decay ratios; e) general safety significance of reactor instability. This standard also does not cover predictor type stability monitors (e.g. frequency domain models which may be used
34、 on line to calculate decay ratio for current reactor conditions). Licensed Copy: sheffieldun sheffieldun, na, Sun Nov 26 11:42:18 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS IEC 61505:1998 2 BSI 05-1999 2 Normative references The following normative documents contain provisions which, through ref
35、erence in this text, constitute provisions of this International Standard. At the time of publication, the editions indicated 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 a
36、pplying the most recent editions of the normative documents indicated below. Members of IEC and ISO maintain registers of currently valid International Standards. IEC 60050(393):1996, International Electrotechnical Vocabulary (IEV) Chapter 393: Nuclear instrumentation: Physical phenomena and basic c
37、oncepts. IEC 60557:1982, IEC terminology in the nuclear reactor field. IEC 60780:1998, Nuclear power plants Electrical equipment of the safety system Qualification. IEC 60880:1986, Software for computers in the safety systems of nuclear power stations. IEC 60964:1989, Design for control rooms of nuc
38、lear power plants. IEC 60980:1989, Recommended practices for seismic qualification of electrical equipment of the safety system for nuclear generating stations. IEC 60987:1989, Programmed digital computers important to safety for nuclear power stations. IEC 61000-4, Electromagnetic compatibility (EM
39、C) Part 4: Testing and measurement techniques. IEC 61226:1993, Nuclear power plants Instrumentation and control systems important for safety Classification. IEC 61343:1996, Nuclear reactor instrumentation Boiling light water reactors (BWR) Measurements in the reactor vessel for monitoring adequate c
40、ooling within the core. IAEA Safety Guide 50-SG-D8:1984, Safety-related instrumentation and control systems for nuclear power plants. 3 Terms and definitions For the purposes of this International Standard, the following definitions are applicable. For terms defined elsewhere, the source is given in
41、 parentheses. 3.1 alarms signals given by annunciators or other display systems to alert the operator to plant and equipment faults and out-of tolerance changes in plant conditions requiring action by the operator IEC 60964 3.2 boiling water reactor (BWR) a nuclear steam supply system in which proce
42、ss steam is generated in the reactor vessel IEC 61343 3.3 coolant water and/or steam for heat removal from the core IEC 61343 3.4 decay ratio decay ratio (DR) of an oscillating system is defined as the ratio between two consecutive maximal of the system impulse response and gives information about t
43、he system stability. An oscillation which decreases in size has a DR 1,0. Decay ratios greater than 1,0 are often referred to as growth rates 3.5 man/machine interface interface between operating staff and I the amount of change in a reactor parameter (core power, core flow rate or core inlet subcoo
44、ling) necessary to reach instability if all other boundary conditions are held constant. 3.15 stable limit cycles a stable limit cycle is an oscillation of the system with a constant frequency and a constant amplitude, such that the oscillation is time invariant 3.16 sub-cooled water water at a temp
45、erature lower than the saturation temperature corresponding to the existing pressure IEC 61343 3.17 superheated steam steam at a temperature higher than the saturation temperature corresponding to the existing pressure IEC 61343 4 Abbreviations APSDAuto Power Spectral Density APRMAverage Power Range
46、 Monitor ARAutoregression ASFAutomatic Safety Function ATWSAnticipated Transient Without Scram CPRCritical Power Ratio DRDecay Ratio DROLDecay Ratio Operating Limit EMIElectromagnetic Interference FFTFast Fourier Transform HWHardware LPRMLocal Power Range Monitor MCPRMinimum Critical Power Ratio M/M
47、Man-Machine PCPersonal Computer PDPhase Difference RFIRadio Frequency Interference RTReal Time STPMSimulated Thermal Power Monitor SLMCPRSafety Limit Minimum Critical Power Ratio SWSoftware WSWork Station VDUVisual Display Unit Licensed Copy: sheffieldun sheffieldun, na, Sun Nov 26 11:42:18 GMT+00:0
48、0 2006, Uncontrolled Copy, (c) BSI BS IEC 61505:1998 4 BSI 05-1999 5 Physics, measurement and analyses of instabilities 5.1 Physics of BWR core instabilities In BWR cores, periodic oscillations in neutron flux, core flow, and core pressure drop can be superimposed on steady-state conditions. Under n
49、ormal operation conditions these oscillations rapidly decay. When the core condition is unstable these oscillatory conditions either diverge or do not decay. Power oscillations may be caused by the reactor control system (e.g. the control loops for reactor pressure, reactor power and feedwater flow), or dynamic interactions between the thermal-hydraulic and neutronic core conditions. 5.1.1 Thermal-hydraulic instability The BWR core consists of a large number of fuel assemblies, exhibiting radially