Components reliability

Nuclear Plant Reliability Data System Annual Reports of Cumulative System and Component Reliability for Period from July 1, 1974, through December 31, 1982, NPRD A02/A03 (INPO 83-034), Institute of Nuclear Power Operations, Atlanta, GA, October 1983. 

Component reliability will vary as a function of the power of a dimensional variable in a stress function. Powers of dimensional variables greater than unity magnify the effect. For example, the equation for the polar moment of area for a circular shaft varies as the fourth power of the diameter. Other similar cases liable to dimensional variation effects include the radius of gyration, cross-sectional area and moment of inertia properties. Such variations affect stability, deflection, strains and angular twists as well as stresses levels (Haugen, 1980). It can be seen that variations in tolerance may be of importance for critical components which need to be designed to a high reliability (Bury, 1974). 

Having previously introduced the key methods to determine the important variables with respect to stress and strength distributions, the most acceptable way to predict mechanical component reliability is by applying SSI theory (Dhillon, 1980). SSI analysis is one of the oldest methods to assess structural reliability, and is the most commonly used method because of its simplicity, ease and economy (Murty and Naikan, 1997 Sundararajan and Witt, 1995). It is a practical engineering tool used for quantitatively predicting the reliability of mechanical components subjected to mechanical loading (Sadlon, 1993) and has been described as a simulative model of failure (Dasgupta and Pecht, 1991). 

Figure 4.37 Component reliability as a function of overall system reliability and number of components in series (adapted from Michaels and Woods, 1989)...

Figure 4.38 Overall system reliability as a function of the mean component reliability, R, for various loading roughnesses (adapted from Carter, 1986)...

This PSA construction process provides results but tends to obscure the interpretation of what led to these results. Sensitivity analyses are basically studies of the effect on risk due to small or large changes in system/component reliability or operability (see Section 2.8). 

Plant Availability. A detailed PSA (2) may be used to analyze the effects of test and maintenance on plant jperability through improved scheduling, component reliability improvement, and improved procedures Hie eost-beiiefit of stocking vs warehousing of feed materials and spare parts may be done to find an optimum ... 

IAEA, 1988, Component Reliability Data for Use in Probabilistic Safety Assessment, lecDoc-478, Vienna. 

EuReDatA Project Report No. 1, Reference Classification Concerning Components Reliability. T. Luisi, Commission of the European Communities, Joint Research Centre, Ispra Establishment, S.A./1.05.01.83.02. 

The main objective of the In-Plant Reliability Data System (IPRDS) was to develop a comprehensive and component-specific data base for PRA and other component reliability-related statistical analysis. Data base personnel visited selected plants and copied all the plant maintenance wor)c requests. They also gathered plant equipment lists and plant drawings and in some cases interviewed plant personnel for Information on component populations and duty cycles. Subsequently, the maintenance records were screened to separate out the cases of corrective maintenance applying to particular components these were reviewed to determine such things as failure modes, severity, and, if possible, failure cause. The data from these reports were encoded into a computerized data base. 

Reliability Analysis Center Handbooks Government and Military Data summaries of hundreds of records by component and environment Electronic component reliability data. i.e. microelectronic devices. high technology components 110. 

DATA BOUNDARY Electronic component reliability data, tronic devices, high technology components... 

The Reliability Analysis Center (RAC) at Rome Air Development Center, Griffiss Air Force Base, maintains a comprehensive accumulation of electronic component reliability data and information representing the combined experiences of hundreds and government, industrial, and independent organizations. 

U.S. Commercial Nuclear Power Plants (Various Components). Reliability of Emergency Diesel Generators at 4.7-14... 

In both cases, the validation process could be divided into two components reliability and relevance. Reliability (precision) is the ability of the method to obtain reproducible results between laboratories while relevance (accuracy) is defined by the comparison of the output from the applied method with the ones obtained using a gold standard test which works as a reference at international levels. 

Developing and publishing a comprehensive database on safety, including component reliability, sensors, and hydrogen releases. 

Component reliability in SOFC Systems for Commercial Operation (CORE-SOFC) (Forschungszentrum Jijlich (D), Riso National Laboratory (DK), Energieonderzoek Centrum Nederland (NL), HaldorTopsoe (DK), Rolls-Royce (UK)). 

The developments of the design and production processes of commercial DLC are driven by the optimization of the materials and production costs, by the processes and component reliability and by the required technology performances [1],... 

Furthermore, the stress and local preferred direction may vary from point to point in the continuum. Thus Eqn. (7) implies that the stress field and unit vector field, i.e. (Ti, xk) and d xk), must be specified to define . Current state of the art in designing structural components uses finite element methods to characterize the stress field. The reader will see shortly that this is conveniently utilized in analyzing component reliability. 

Overall, the component reliability is a challenge to fnel cell mannfactnrers as well as their component snppliers. The stack is only one of several snbsystems in a PEM fuel cell system with hundreds of parts and components. Component compatibility, which includes both chemical and mechanical properties, plays an important role in system reliability and overall performance. To select the best materials/design for a system component, one mnst first stndy its properties (physical, chemical, mechanical, and electrochanical) nnder relevant conditions snch as temperature, pressure, and composition. Eor example, the reactant side of a PEM fuel cell bipolar plate (all sealing materials and plate components) mnst be able to tolerate high humidity, temperature... 

Test many subsystems and components to failure where use conditions are recreated in the test environment This allows one to develop empirically the component reliability functions and then to derive analytically the system reliability function. 

Predict component reliability from the data bank of the failure rates. 

Compute system reliability from component reliability. 

Assumption 1 Safety is increased by increasing system or component reliability. If components or systems do not fail, then accidents will not occur. 

Solution Equation 5-1 shows that system reliability equals the product of component reliabilities. The problem provides availabilities, not reliabilities, but the same equation applies as the RBD method is a probability combination method. Therefore, the system availability equals... 

Solution Equation 5-3 shows that system reliability equals the union of component reliabilities. Therefore, the system reliability equals... 

ECSS-Q-HB-30-08A, January 2011. Space Product Assurance. Components Reliability Data Sources and Their Use. European Cooperations for Space Standardization (ECSS), ECSS Secretariat, ES A-ESTEC Requirements Standards Division, Noordwijk, The Netherlands. 

Munoz, A., Martorell, S. Senadeil, V. 1997. Genetic algorithms in optimizing surveillance and maintenance of components. Reliability Engineering and System Safety 1997 57 107-20. 

Finn, J. 1998. Electronic component reliability, Chichester [UK] John Wiley Sons Ltd. 

This proposedreliability-oriented topology approach introduces to the optimization of components reliability-based properties as well as of the system topology variation/optimization, which may lead to better system reliability. Parallel, costs of the system can be integrated into the overall optimization process and rmused signal flows, redundancies can be detected. 

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