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1、BRITISH STANDARD BS IEC 62342:2007 Nuclear power plants Instrumentation and control systems important to safety Management of ageing ICS 27.120.20 ? BS IEC 62342:2007 This British Standard was published under the authority of the Standards Policy and Strategy Committee on 28 September 2007 BSI 2007
2、ISBN 978 0 580 56066 8 National foreword This British Standard is the UK implementation of IEC 62342:2007. The UK participation in its preparation was entrusted to Technical Committee NCE/8, Reactor instrumentation. A list of organizations represented on this committee can be obtained on request to
3、its secretary. This publication does not purport to include all the necessary provisions of a contract. Users are responsible for its correct application. Compliance with a British Standard cannot confer immunity from legal obligations. Amendments issued since publication Amd. No. DateComments IEC 6
4、2342 Edition 1.0 2007-08 INTERNATIONAL STANDARD Nuclear power plants Instrumentation and control systems important to safety Management of ageing BS IEC 62342:2007 CONTENTS INTRODUCTION.4 1 Scope.6 1.1 Management of physical ageing 6 1.2 Management of technology ageing (obsolescence)6 1.3 Safety goa
5、l of this standard.6 2 Normative references .6 3 Terms and definitions .6 4 Background 9 5 Requirements for ageing management .10 5.1 General.10 5.2 Methodology10 5.3 Process.11 6 Understanding I steps to be followed to establish an ageing management program for NPP I and tracking of performance ind
6、ices such as response time and calibration stability as the means to manage the ageing of sensors and transmitters. It is recognized that testing and monitoring techniques used to evaluate the ageing condition of NPPs I thus the installed life of the component would be less than 40 years. IEC 60780,
7、 3.10 3.10 modernization replacement or upgrading with newer systems and components. Replacement is the term to be used when there is no change in requirements; upgrading is the terms to be used when the level of requirements increases NOTE 1 Backfit, refit, retrofit, refurbish and upgrade are simil
8、ar terms which are often used interchangeably. They only differ in shades of meaning (IAEA-TECDOC-1066). Upgrading is the term to be used when there is an increase in requirements. Upgrading also includes the implementation of new functionality. NOTE 2 Replace and renew are similar and often interch
9、angeable. The terms are used from a single component up to the complete I 9 BS IEC 62342:2007 b) obsolescence of equipment (systems and components) in terms of both replacement parts and suppliers support. NPP I and b) those which could lead to failure during accidental conditions (including seismic
10、 and design basis accident conditions). The parameters relevant to I however, ageing degradation due to a combination of more than one stress may exceed the sum of the individual effects. 6.3 Ageing mechanisms and ageing effects The susceptibility of equipment to ageing mechanisms and consequent age
11、ing effects should be determined through an analysis of the behaviour of the individual materials and components that make up the I evaluating ageing degradation for I ageing stresses; intended function versus qualification; surveillance tests and maintenance requirements; support resources; and doc
12、umentation requirements. The requirements relative to these steps are described in the following subclauses. 7.2 Selection of I and within this list of safety-related components, identifying those which may be susceptible to ageing mechanisms (see Clause 6). Examples of I cables and connectors; neut
13、ron flux detectors; electronic cards; and pressure sensing lines (impulse lines). 7.2.2 Identification of I type (model, manufacturer, etc.); 16 BS IEC 62342:2007 degree of environmental protection; operating and environmental conditions and locations; age and required operating life; qualification
14、requirements; and history of failure. 7.2.4 Failure analysis Equipment or component parts shall be analysed with respect to the impact of their failure on the safety function in the set of operating conditions. Faults and failure modes due to ageing mechanisms shall be considered. Originally, all co
15、mponents should be considered as sensitive for ageing until the opposite has been shown. It should be noted that ageing can be included by synergy effects. The following factors should be considered in the failure analysis. Particular ageing degradation of certain components may lead to non-safe or
16、un-detected modes of failure. Ageing degradation can induce non-compliance to specification for normal operation or accident condition qualification. The effects of ageing on construction materials that are not normally regarded as I see Clause 6. Annex A gives guidance for characterizing I equipmen
17、t functioning conditions that are likely to cause stress and induce ageing mechanisms (7.4.3); equipment design, failure analysis (7.2.4), and degree of environmental protection; testing or maintenance actions (preventive or corrective) normally carried out on the equipment to alleviate the effects
18、of the ageing mechanism (Clause 8) or identify its consequences; equipment containing components with predetermined lifetimes (as indicated by design specifications or qualification requirements); and support resources likely to be affected by ageing (7.7). 17 BS IEC 62342:2007 7.3 Evaluating ageing
19、 degradation of I to define suitable counter-measures if necessary; to demonstrate that the risks associated with ageing degradation can be adequately controlled using results of failures trend analysis; and to demonstrate that the required level of plant safety can be assured with time. Two approac
20、hes for the method of evaluation are possible depending on the equipment design and qualification principles. a) An analytical (involving mathematical analysis) approach may be applied where the equipment qualification explicitly requires component lifetimes to be specified and if the equipment desi
21、gn allows this. This may be a regulatory requirement. The analytical approach should be based on calculations of expected lifetimes for components taking into account quantitatively the equipment stress history and mathematical models for ageing mechanisms. End-of-lifetime dates for replacing equipm
22、ent and components can be defined. For example, methods exist to establish the expected life of some equipment using calculations based on the Arrhenius model. This approach mainly concerns equipment inside the containment which is used in post accident conditions. Initial qualification (by pre-agei
23、ng) data are used and the equipment lifetime is recalculated with an Arrhenius model in order to prove a new qualified lifetime. It shall be noted that the justification for using such models as Arrhenius and their level of confidence has to be proven in use and cannot be claimed a priori as represe
24、ntative for all types of components or for long qualified life. b) A pragmatic approach based on a combination of equipment testing, visual inspection, operating experience, and engineering judgment should be used when equipment lifetimes are not specified or cannot be modelled mathematically with a
25、ny degree of confidence. The approach could also be applicable for equipment outside the containment having specified component lifetimes. In this approach, qualitative judgments may be made in order to anticipate or detect early enough in a components life, signs that it could be degraded regardles
26、s of the design requirements necessary for ensuring safety; and define suitable responses to the onset of ageing degradation, and if necessary, take corrective measures (including repair or replacement) to assure the required level of safety. In this approach, end of equipment life is based on actua
27、l performance and not on theoretical lifetime. A practical application may combine both the analytical and the pragmatic approaches mentioned above. 7.4 Ageing stresses 7.4.1 General The ageing stresses that are relevant to selected I stresses which are specific to the installed location or operatio
28、nal and maintenance requirements (proximity to heat sources, radiation sources, frequent dismantling or disconnection/reconnection for access or test); and the electrical supply quality for each I the frequency of operation; where possible internal stresses arising from equipment or system operation
29、 (for example, number of mechanical contact operations, heating effect when powered-up, etc.); and an examination of the I an estimation of the number of operations during each period of service; and specified life before replacement. Any changes in operating conditions affecting I document resource
30、s; testing and calibration tools; trending information (for example, IR results, response time, information, etc.); and experience from other plants. 7.8 Documentation requirements A compilation of the results of all analyses identifying I and define suitable responses to the onset of ageing degrada
31、tion and, where necessary to take corrective measures, so as to assure the required level of safety. The ageing control programs may be a part of existing (preventive or predictive) maintenance programs. The maintenance of I development of methods for repair or replacement; plant and equipment monit
32、oring; collection and analysis of data; and initiating new R exceptional maintenance planning and anticipation of major repairs or replacements; major outages/periodic safety review bringing the formal evidence that adequate management of ageing is achieved over a specified period (for example, ten-
33、year period); plant life duration programme coordinating strategies for the future, research, and development, etc.; and managing human resources needs to foresee sufficient levels of adequately trained staff for the future. 9.3 Identifying long-term operating strategies and I organization of the ma
34、intenance teams; number of plants equipped with the same range of equipment; role of the plant operators in the technical maintenance tasks; and level of externalization of maintenance works. The long-term monitoring policy should include contractual provisions with system builders and original equi
35、pment manufacturers; monitoring manufacturers ability to continue to supply; monitoring of obsolescence of components (software and hardware); requirements for spare parts stocks; and economical analysis (cost of obsolescence/cost of induced plant unavailability). 9.5 Quality assurance This standard
36、 assumes that a quality assurance program consistent with the requirements of IAEA 50-C/SG-Q exists as an integral part of the NPP project and that it provides control of the constituent activities. Requirements from IEC 61513 should be applied for the establishment of quality assurance programs and
37、 all related activities to achieve and verify the required quality for the ageing management process. 9.6 Reporting The ageing management process should be fully documented in a report which describes the organization, method, and results of the various stages of the ageing management programme, sum
38、marizes the historical test data, reports of the analysis, and makes clear recommendations for action to be taken to mitigate consequences of the ageing processes. Documentary evidence corresponding to all safety related requirements of this standard shall be provided. Demonstration of ageing manage
39、ment of I anticipated equipment performance or reliability problems; and historical problems of a “one-off” nature which were costly to rectify. Methodologies have been developed to extract such information. These typically define a structured series of questions for plant staff. It is worth noting
40、that such interviews should not be restricted to maintenance staff; operations and engineering staff will also possess valuable opinions and information. 25 BS IEC 62342:2007 A.2.5 Other data sources The ageing evaluation should not be restricted to local data. Information from other sources should
41、be sought including reports from other plants, other utilities, and industry-wide research programmes. A.3 Testing and monitoring The following provides examples of I the in situ response time testing of resistance temperature detectors (RTDs) and thermocouples (T/Cs) using the loop current step res
42、ponse (LCSR) method; on-line measurement of response time of pressure transmitters using the noise analysis technique; in situ testing of cables and connectors; on-line detection of blockages and voids in pressure sensing lines; and remote testing of the attachment of temperature sensors and strain
43、gauges to solid materials. Annex B provides more information. A.3.2 Condition monitoring Condition monitoring has gained interest in many industries including the nuclear power industry. Recent preventive maintenance technologies have provided cost-effective tools such as PC-based data acquisition a
44、nd analysis systems to help monitor the performance of equipment on a periodic or continuous basis while the plant is operating. This can help justify running the equipment without periodic hands-on verification tests until a malfunction is detected or the equipment degradation has exceeded a thresh
45、old. An example of a successful application of condition monitoring is on-line drift monitoring of pressure, level, and flow transmitters. Through on-line monitoring, pressure transmitters that drift beyond an acceptable limit are identified. These transmitters are then calibrated and those which do
46、 not drift are not calibrated or calibrated less frequently. This helps optimize the frequency of calibration of pressure transmitters and can be extended to other process instruments. It can cover not only sensors and transmitters but also the rest of an instrument channel. A.3.3 Environmental moni
47、toring Monitoring the temperature, radiation, humidity, and other conditions to which an I normal use; and end of life (“wear-out”). Figure B.1 Bathtub curve model for failure rates of electronic components Hypothetical failure rate versus time Time Failure rate Infant mortality End of life (wear-ou
48、t) Normal life low “constant“ failure rate IEC 1378/07 27 BS IEC 62342:2007 The initial phase is often used by manufacturers during work testing, to ensure delivery of reliable components. Otherwise, these failures are revealed during initial commissioning or early operation. The latter two phases o
49、f operation are of direct concern to ageing. There are accepted models and parameters for electronic component reliability during normal operation. However, there are no comparable accepted models for the end-of-life phase. Indeed, as lifetimes are known to vary dramatically between identical components in similar applications, such a model is likely