1、 g49g50g3g38g50g51g60g44g49g42g3g58g44g55g43g50g56g55g3g37g54g44g3g51g40g53g48g44g54g54g44g50g49g3g40g59g38g40g51g55g3g36g54g3g51g40g53g48g44g55g55g40g39g3g37g60g3g38g50g51g60g53g44g42g43g55g3g47g36g58important to safety Management of ageing ICS 27.120.20Nuclear power plants Instrumentation and cont
2、rol systems BRITISH STANDARDBS IEC 62342:2007BS IEC 62342:2007This British Standard was published under the authority of the Standards Policy and Strategy Committee on 28 September 2007 BSI 2007ISBN 978 0 580 56066 8Amendments issued since publicationAmd. No. Date CommentsCompliance with a British S
3、tandard cannot confer immunity from legal obligations.National forewordThis 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 ca
4、n be obtained on request to its secretary.This publication does not purport to include all the necessary provisions of a contract. Users are responsible for its correct application.IEC 62342Edition 1.0 2007-08INTERNATIONAL STANDARD Nuclear power plants Instrumentation and control systems important t
5、o safety Management of ageing BS IEC 62342:2007CONTENTS INTRODUCTION.4 1 Scope.6 1.1 Management of physical ageing 6 1.2 Management of technology ageing (obsolescence)6 1.3 Safety goal of this standard.6 2 Normative references .6 3 Terms and definitions .6 4 Background 95 Requirements for ageing man
6、agement .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 indices such as response time and calibration stability as the means to manage the ageing of sensors and transmitters. I
7、t 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, 3.10 3.10 modernization replacement or upgrading with newer systems and components. Replacement is the term to be us
8、ed 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 similar terms which are often used interchangeably. They only differ in shades of meaning (IAEA-TECDOC-1066). Upgrading is
9、 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 interchangeable. The terms are used from a single component up to the complete I 9 BS IEC 62342:2007b) obsolescence of equip
10、ment (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 and design basis accident conditions). The parameters relevant to I however, ageing degradation due to a combination
11、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 ageing effects should be determined through an analysis of the behaviour of the individual materials and components that
12、make up the I evaluating ageing degradation for I ageing stresses; intended function versus qualification; surveillance tests and maintenance requirements; support resources; and documentation requirements. The requirements relative to these steps are described in the following subclauses. 7.2 Selec
13、tion 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; neutron flux detectors; electronic cards; and pressure sensing lines (impulse lines). 7.2.2 Identification of I type (mode
14、l, manufacturer, etc.); 16 BS IEC 62342:2007 degree of environmental protection; operating and environmental conditions and locations; age and required operating life; qualification requirements; and history of failure. 7.2.4 Failure analysis Equipment or component parts shall be analysed with respe
15、ct 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 components should be considered as sensitive for ageing until the opposite has been shown. It should be noted that agein
16、g 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 un-detected modes of failure. Ageing degradation can induce non-compliance to specification for normal operation or ac
17、cident 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 equipment functioning conditions that are likely to cause stress and induce ageing mechanisms (7.4.3); equipment design, failu
18、re 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 of the ageing mechanism (Clause 8) or identify its consequences; equipment containing components with predetermined li
19、fetimes (as indicated by design specifications or qualification requirements); and support resources likely to be affected by ageing (7.7). 17 BS IEC 62342:20077.3 Evaluating ageing degradation of I to define suitable counter-measures if necessary; to demonstrate that the risks associated with agein
20、g 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 approaches for the method of evaluation are possible depending on the equipment design and qualification principles. a) An ana
21、lytical (involving mathematical analysis) approach may be applied where the equipment qualification explicitly requires component lifetimes to be specified and if the equipment design allows this. This may be a regulatory requirement. The analytical approach should be based on calculations of expect
22、ed lifetimes for components taking into account quantitatively the equipment stress history and mathematical models for ageing mechanisms. End-of-lifetime dates for replacing equipment and components can be defined. For example, methods exist to establish the expected life of some equipment using ca
23、lculations based on the Arrhenius model. This approach mainly concerns equipment inside the containment which is used in post accident conditions. Initial qualification (by pre-ageing) data are used and the equipment lifetime is recalculated with an Arrhenius model in order to prove a new qualified
24、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 representative for all types of components or for long qualified life. b) A pragmatic approach based on a combination of equip
25、ment testing, visual inspection, operating experience, and engineering judgment should be used when equipment lifetimes are not specified or cannot be modelled mathematically with any degree of confidence. The approach could also be applicable for equipment outside the containment having specified c
26、omponent 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 regardless of the design requirements necessary for ensuring safety; and define suitable responses to the onset of ageing degrad
27、ation, 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 actual performance and not on theoretical lifetime. A practical application may combine both the analytical and the pragmati
28、c 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 operational and maintenance requirements (proximity to heat sources, radiation sources, frequent dismantling or disconnection/r
29、econnection 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 (for example, number of mechanical contact operations, heating effect when powered-up, etc.); and an examination of th
30、e 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 resources; testing and calibration tools; trending information (for example, IR results, response time, information, etc.); and
31、 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 degradation and, where necessary to take corrective measures, so as to assure the required level of safety. The ageing control
32、 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 monitoring; collection and analysis of data; and initiating new R exceptional maintenance planning and anticipation of major
33、 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-year period); plant life duration programme coordinating strategies for the future, research, and development, etc.; an
34、d 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 maintenance teams; number of plants equipped with the same range of equipment; role of the plant operators in the technic
35、al maintenance tasks; and level of externalization of maintenance works. The long-term monitoring policy should include contractual provisions with system builders and original equipment manufacturers; monitoring manufacturers ability to continue to supply; monitoring of obsolescence of components (
36、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 assumes that a quality assurance program consistent with the requirements of IAEA 50-C/SG-Q exists as an integral part
37、 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 all related activities to achieve and verify the required quality for the ageing management process. 9.6 Reporting The
38、 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, summarizes the historical test data, reports of the analysis, and makes clear recommendations for action to be taken to mi
39、tigate consequences of the ageing processes. Documentary evidence corresponding to all safety related requirements of this standard shall be provided. Demonstration of ageing management of I anticipated equipment performance or reliability problems; and historical problems of a “one-off” nature whic
40、h 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 that such interviews should not be restricted to maintenance staff; operations and engineering staff will also possess
41、valuable opinions and information. 25 BS IEC 62342:2007A.2.5 Other data sources The ageing evaluation should not be restricted to local data. Information from other sources should be sought including reports from other plants, other utilities, and industry-wide research programmes. A.3 Testing and m
42、onitoring 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 response (LCSR) method; on-line measurement of response time of pressure transmitters using the noise analysis technique; i
43、n 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 gauges to solid materials. Annex B provides more information. A.3.2 Condition monitoring Condition monitoring has gained
44、 interest in many industries including the nuclear power industry. Recent preventive maintenance technologies have provided cost-effective tools such as PC-based data acquisition and analysis systems to help monitor the performance of equipment on a periodic or continuous basis while the plant is op
45、erating. 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 threshold. An example of a successful application of condition monitoring is on-line drift monitoring of pressure, level, and
46、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 not drift are not calibrated or calibrated less frequently. This helps optimize the frequency of calibration of pressur
47、e 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 monitoring Monitoring the temperature, radiation, humidity, and other conditions to which an I normal use; and end of life (
48、“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-out) Normal life low “constant“ failure rate IEC 1378/07 27 BS IEC 62342:2007The initial phase is often used by manufactur
49、ers during work testing, to ensure delivery of reliable components. Otherwise, these failures are revealed during initial commissioning or early operation. The latter two phases of 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
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