Maintenance Management Support Systems for Component Aging Estimation at Nuclear Power Plants

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<ul><li><p>This article was downloaded by: [University of Illinois Chicago]On: 27 October 2014, At: 20:57Publisher: Taylor &amp; FrancisInforma Ltd Registered in England and Wales Registered Number: 1072954 Registeredoffice: Mortimer House, 37-41 Mortimer Street, London W1T 3JH, UK</p><p>Journal of Nuclear Science andTechnologyPublication details, including instructions for authors andsubscription information:</p><p>Maintenance Management SupportSystems for Component Aging Estimationat Nuclear Power PlantsShunichi SHIMIZU a , Yasumasa ANDO b , Toshihiko MORIOKA b &amp;Naoaki OKUZUMI ba Nuclear Engineering Laboratory , Toshiba Corp. , Ukishima-cho,Kawasaki-ku, Kawasaki , 210b Isogo Nuclear Engineering Center , Toshiba Corp. , Shinsugita-cho,Isogo-ku, Yokohama , 235Published online: 15 Mar 2012.</p><p>To cite this article: Shunichi SHIMIZU , Yasumasa ANDO , Toshihiko MORIOKA &amp; Naoaki OKUZUMI (1991)Maintenance Management Support Systems for Component Aging Estimation at Nuclear Power Plants,Journal of Nuclear Science and Technology, 28:11, 1041-1057, DOI: 10.1080/18811248.1991.9731467</p><p>To link to this article:</p><p>PLEASE SCROLL DOWN FOR ARTICLE</p><p>Taylor &amp; Francis makes every effort to ensure the accuracy of all the information (theContent) contained in the publications on our platform. However, Taylor &amp; Francis, ouragents, and our licensors make no representations or warranties whatsoever as to theaccuracy, completeness, or suitability for any purpose of the Content. Any opinions andviews expressed in this publication are the opinions and views of the authors, and arenot the views of or endorsed by Taylor &amp; Francis. The accuracy of the Content should notbe relied upon and should be independently verified with primary sources of information.Taylor and Francis shall not be liable for any losses, actions, claims, proceedings, demands,costs, expenses, damages, and other liabilities whatsoever or howsoever caused arisingdirectly or indirectly in connection with, in relation to or arising out of the use of theContent.</p><p>This article may be used for research, teaching, and private study purposes. Anysubstantial or systematic reproduction, redistribution, reselling, loan, sub-licensing,systematic supply, or distribution in any form to anyone is expressly forbidden. Terms &amp;Conditions of access and use can be found at</p><p></p></li><li><p>Journal of NUCLEAR SCIENCE and TECHi':OLOGY, 28[11], pp. 1041-1057 (November 1991). </p><p>TECHNICAL REPORT </p><p>Maintenance Management Support Systems for Component Aging Estimation </p><p>at Nuclear Power Plants </p><p>Shunichi SHIMIZU, </p><p>Nuclear Engineering Laboratory, Toshiba Corp.* </p><p>Yasumasa ANDO, Toshihiko MORIOKA and Naoaki OKUZUMI </p><p>!sago Nuclear Engineering Center, Toshiba Corp.** </p><p>Received October 8, 1990 </p><p>1041 </p><p>Maintenance Management Support Systems (MMSSs) for nuclear power plants have been developed using component aging estimation methods and decision tree analysis for maintenance planning. The former evaluates actual component reliability through statistical analysis on field maintenance data. The latter provides preventive maintenance (PM) planning guidance using heuristic expert knowledge and estimated reliability parameters. </p><p>The following aspects have been investigated: (1) A systematic and effective method of managing components/parts design information and </p><p>field maintenance data (2) A method for estimating component aging based on a statistical analysis of field main-</p><p>tenance data (3) A method for providing PM planning guidance using estimated component reliability I </p><p>performance parameters and decision tree analysis. Based on these investigations, two MMSSs were developed. One deals with "general </p><p>maintenance data", which are common to all component types and are amenable to common data handling. The other system deals with "specific maintenance data", which are specific to an individual component type. Both systems provide PM planning guidance for PM cycles propriety and the PM work priority. The function of these systems were verified using simu-lated maintenance data. </p><p>KEYWORDS: nuclear power plants, reactor maintenance, maintenance management system, reactor components, aging estimation, reliability, performance, decision tree analysis, maintenance data, data processing, expert systems, statifltical analysis </p><p>I. INTRODUCTION Preventive Maintenance (PM) planning in </p><p>nuclear power plants has recently become very important due to the increasing number of power stations and their longer periods of operation. Preventive maintenance planning must include measures against component de-</p><p>gradation, while maintaining maximum com-ponent reliability and plant availability at minimum cost. This is a very complex task for plant personnel, since it requires making decisions based on a significant amount of field maintenance data and on a broad know-* Ukishima.cho, Kawasaki-ku, Kawasaki 210. ** Shinsugita.cho, Isogo.ku, Yokohama 235. </p><p>-69-</p><p>Dow</p><p>nloa</p><p>ded </p><p>by [</p><p>Uni</p><p>vers</p><p>ity o</p><p>f Il</p><p>linoi</p><p>s C</p><p>hica</p><p>go] </p><p>at 2</p><p>0:57</p><p> 27 </p><p>Oct</p><p>ober</p><p> 201</p><p>4 </p></li><li><p>1042 TECHNICAL REPORT (S. Shimizu et al.) ]. Nucl. Sci. Techno!., </p><p>ledge regarding design conditions, operating conditions, and maintainability of various com-ponents. Since component reliability decreases with degradation and increases with appro-priate countermeasures, such as PM work or design modifications, it is necessary to take timely and effective measures based on the evaluation of actual component reliability. </p><p>To deal with this complex situation, several studies on component aging estimation tech-niques and Maintenance Management Support Systems (MMSSs) have been carried out for specific component types and plant systems </p></li><li><p>Vol. 28, No. 11 (Nov. 1991) TECHNICAL REPORT (S. Shimizu et al.) 1043 </p><p>component aging estimation techniques is given, followed by an explanation of the two MMSSs. </p><p>1. Component Aging Estimation In order to consider methods for estimating </p><p>component aging, a component aging model should be studied first. </p><p>Figure 1 shows a conceptual outline of the component aging model. First, component aging is induced by many "aging factors", such as time, temperature, and stress applied on each part. Second, a part's reliability decreases due to "aging mechanisms" which are determined by complex physical/chemi-</p><p>cal/electrical aging effects. For example, Arrhenius's equation, which expresses an elec-trical capacitor's "aging mechanism", is deter-mined by the relationship between capacity loss and ambient temperature. Third, each part has an "inherent reliability", which is mainly determined by the original design and manufacture processes. Finally, a part's "time-dependent aging pattern", or its performance deterioration, is represented by a combination of "aging factors", "aging mechanisms" and "inherent reliability". A part's "performance deterioration" pattern is accordingly modified by the imposed "aging factors". </p><p>-----[Component]--------------------------------------------------~ </p><p>~~~~~~~-n] rerform~tnce </p><p>[Parts-2]---------...., ~ deterior11t ion ...._'":11-.r-------...., </p><p>(Parts level) ~ Complex -'' aging </p><p>[ Parts-1]-------------., </p><p>''''"::.::. ~ ,,,,,,, Aging Aging factors mechanisms </p><p>- Complex aging effects </p><p>1 ~ deterioration </p><p>(Parts level) </p><p>lnher~nt Tim~-dependent Performance ~deterioration </p><p>(Parts level) </p><p>Time-dependent aging pattern </p><p>reliability ~ aging (Parts Level) pattern </p><p>End of Tolerance Component's E-- perfnrm~ncP. </p><p>deterior~tion </p><p>nseful I if~ !----(Life sp~nl threshold </p><p>Fig. 1 Conceptual outline for component aging model </p><p>A component's "performance deterioration" is represented by both parts' "performance deterioration" and parts' "inherent reliability" as determined by the original design. A component subsequently ends its useful life when its reliability goes below the tolerance threshold. </p><p>In order to estimate component aging based on this model, four different methods can be considered, as follows : </p><p>(1) Aging Mechanism Estimation The purpose of this method is to estimate </p><p>a component aging mechanisms using numer-ical equations to describe the component's physical/chemical/electrical behavior. These mechanisms must be verified by making vari-ous aging acceleration tests and by compiling and interpreting component performance data. </p><p>(2) Aging Factor Management The purpose of this method is, first, to </p><p>discern the dominant aging factors for a </p><p>-71-</p><p>Dow</p><p>nloa</p><p>ded </p><p>by [</p><p>Uni</p><p>vers</p><p>ity o</p><p>f Il</p><p>linoi</p><p>s C</p><p>hica</p><p>go] </p><p>at 2</p><p>0:57</p><p> 27 </p><p>Oct</p><p>ober</p><p> 201</p><p>4 </p></li><li><p>1044 TECHNICAL REPORT (S. Shimizu et a/.) ]. Nucl. Sci. Techno! .. </p><p>component/part, such as ambient temperature, humidity, or stress, and, second, to manage their history and component's operating re-cords. </p><p>(3) Performance Parameters Monitoring The purpose of this method is, first, to </p><p>determine the component performance param-eters which well represent its deterioration, and, second, to monitor their deterioration patterns with respect to time. </p><p>(4) Reliability Parameters Evaluation The purpose of this method is to evaluate </p><p>the component reliability parameters based on statistical analysis of field maintenance data, including normal/unscheduled parts replace-ment/overhaul data, the time between replace-ments/overhauls, deterioration modes, and deterioration seriousness. </p><p>In the above four methods, (1) and (2) demand relatively high development costs to manage the aging factors and to verify the </p><p>developed aging models. Hence, these methods are applicable only for a few very important components at the current technological level. On the other hand, methods (3) and (4) can be applied to the estimation of component aging in relatively simple and practical ways. Therefore, in the present paper, methods (3) and (4) are examined. </p><p>2. Aging Data Management Table 1 shows two ways in which com-</p><p>ponent aging data management, for data ob-tained by the four above classified methods, can be practically used in a nuclear facility's computer database system. The first approach is specific component aging data management for an individual component category. The above mentioned (1), (2) and (3) methods are classified into this approach. Second is general component aging data management for all component categories. Method (4) is segre-gated into this category. </p><p>Table 1 Component aging data management method classifications </p><p>f- Specific Ll</p></li><li><p>Vol. 28, No. 11 (Nov. 1991) TECHNICAL REPURT (S. Shimizu et a!.) 1045 </p><p>method must be developed for each individual component category. This leads to high de-velopment costs. </p><p>The objective of the second approach is to manage a component's "general maintenance data", such as normal/unscheduled replace-ment data, overhaul/inspection data, and de-terioration modes. This approach is based on a statistical analysis on field maintenance data, and provides component reliability parameters, such as failure rates, mean time between failures (MTBF), and failure distributions. This approach, therefore, has high flexibility, and also has the advantage of lower development costs. </p><p>the two component aging data management approaches mentioned above, two MMSSs, namely the EMICS and the CRD-PMPSS, will be explained in Chaps. III and IV. </p><p>ill. GENERAL MAINTENANCE MANAGEMENT SUPPORT </p><p>SYSTEM </p><p>This chapter describes an outline of EMICS -an example of general maintenance data management. </p><p>1. EMICS System Outline </p><p>In order to validate the effectiveness of </p><p>Figure 2 shows the EMICS conceptual de-sign. It consists of the following subsystems: (1) Data management subsystem, (2) Database subsystem and (3) Data evaluation subsystem. </p><p>r1 Input data sheet} rlEquipment maintenance information control system~ * Component data I I * Parts data 1Data Management Subsystem I ,c::; * General mainte-</p><p>nance data l) Component data management function * Expert kn01~ledge 2) Parts data management function </p><p>d11ta 3) ~lainten11nce rl11ta management function 4) Expert know)Pcige data m111111gemPnt </p><p>function D 5) Naster code data management function </p><p>r-{ User l- a ~ I Evaluation Subsystem ~ </p><p>t * Plant designer , 1oata * PM planner/ </p><p>~ a </p><p>technician 1) Statistical maintenance data analysis * etc function </p><p>t 2) PM planning guidance function b r4 Main Outpu~ </p><p>(Using decision tree analysis) a </p><p>s * Component reli-</p><p>rispecific Information Retrieval Subsystem ~ ability parameters~ e * P~l planning guid- ~ * Component/part PN schedule diagram </p><p>ance * Component/part PM history list * Similar previous failures 1 i st. etc .............. </p><p>* etc </p><p>Fig. 2 EMICS conceptual design </p><p>The EM!CS was developed on an Engi-neering Work Station (EWS; TOSHIBA AS-3000 series). Plant designers, maintenance planners/ technicians, and operational personnel can exchange information on this system using </p><p>input/output terminals, such as keyboards, color graphics monitors, printers and icons. </p><p>( 1) Data Management Subsystem This subsystem manages four kinds of data </p><p>sheet: "component data sheet", "component </p><p>-73-</p><p>Dow</p><p>nloa</p><p>ded </p><p>by [</p><p>Uni</p><p>vers</p><p>ity o</p><p>f Il</p><p>linoi</p><p>s C</p><p>hica</p><p>go] </p><p>at 2</p><p>0:57</p><p> 27 </p><p>Oct</p><p>ober</p><p> 201</p><p>4 </p></li><li><p>1046 TECHNICAL REPORT (S. Shimizu et a[.) j. Nucl. Sci. Techno!., </p><p>parts data sheet", "general maintenance data sheet" and "expert knowledge data sheet". The last sheet is an extension of the Failure Mode, Effects and Criticality Analysis (FME/ CA) sheet. It not only manages failures and their consequences, but also contains broad PM planning information, such as failure detectability and the maintenability for each failure mode. </p><p>In addition to these four data sheets, the subsystem has a function which allows it to manage master codes. These master codes are abbreviations which represent routine in-put data, such as plant name, component/part name, failure mode, etc. These master codes contribute to the standardization of input in-formation, increasing data retrieval speed, and minimizing user's interaction time, all of which are very important factors. By using these master codes, users can easily update, retrieve, and delete data in the database. </p><p>As shown in Fig. 3, maintenance data (see </p><p>the shaded portion) are compressed into stand-ardized coded data sequences, such as "2-o", "1-,:,-crack-(S)-VT" and "1-x-corrosion-(S)-VT". The "2-o" indicates that two "0-rings" were replaced at the scheduled maintenance time and were found in a satisfactory condition. The "1-,:,-crack-(S)-VT" indicates that one "0-ring" was replaced at the scheduled maintenance time, but was found to be in an unsatisfactory condition (a small "crack" dis-covered by visual testing). The "1- x -corrosion-(S)-VT" indicates that one "0-ring" was replaced before the scheduled time, since it had a small amount of "corrosion" discovered dur-ing visual testing. Thi...</p></li></ul>


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