Reliability data update method for emergency diesel generator of Daya Bay Nuclear Power Plant (original) (raw)
Related papers
Diesel generators testing interval optimization and reliability data uncertainty minimization
The object of the considered work was to investigate the possibility to change and optimize the testing intervals in such way, that the safety level of Ignalina NPP would not be decreased. The investigation of Emergency Diesel Generators System (EDGS) at Ignalina Nuclear Power Plant is performed applying the reliability related measures. In order to estimate and minimize the reliability data uncertainty the Bayesian updating approach is also investigated. As the considered measure and failure data are mainly related to unavailability of EDGS, the unavailability model is considered and used for the testing interval optimization.
Diesel generator system reliability control and testing interval optimization
Energetika
The aim of the current work was to investigate the possibility to change and optimize the testing intervals of the Emergency Diesel Generators System (EDGS) at the Ignalina Nuclear Power Plant (NPP) in such a way that the safety level of the Ignalina NPP would not be decreased. The investigation of EDGS was performed applying the conservative measures related to system reliability. In order to estimate and minimize the reliability data uncertainty, the Bayesian updating approach was also investigated. As these measures and failure data are mainly related to EDGS unavailability, the system unavailability model has been developed and used for testing interval optimization.
International Journal of Mathematical, Engineering and Management Sciences
Nuclear power plants (NPPs) are subjected to events such as equipment failures, human errors and common-cause failures, in an environment of complex maintenance, inspection and testing managements. These events will affect the reliability of safety-related systems, as well as the risk level of the plant. Reliability block diagram (RBD) is often used to analyze the effect of item failures on system availability, taking into account their physical arrangement in the system. Fault tree (FT) is a commonly used technique for analyzing risk and reliability in nuclear, aeronautical and chemical industries. It represents graphically the basic events that will cause an undesired top event. Loss of electrical power is one of the main events that influences safe operation of NPPs, as well as accident prevention and mitigation. In case of unavailability of offsite power, emergency diesel generators (EDGs) supply onsite electrical power. This paper carries out reliability analyses of EDGs of NPP...
A fast and robust Bayesian update of components failure rates in a nuclear power plant
2020
This paper presents the algorithm and the results of a novel, robust, fast and accurate Bayesian update methodology that is developed at Leibstadt Nuclear Power Plant for components failure rate calculation as required in the Probabilistic Safety Assessment (PSA). In PSA, component failure rates are modelled using probability density functions representing the uncertainty range of the failure rates. International generic failure rates (prior information) need to be coupled with plant-specific failure statistics (evidence) through a Bayesian update process to obtain a best estimate of plant-specific reliability parameters (posterior information). It was noticed, that commonly used numerical integration functions (e.g. MATLAB built-in integral function) often result in numerical instabilities when applied to the required integral in Bayesian updates. A more robust algorithm was developed to resolve these instabilities. This algorithm covers all probability density functions (pdfs) of interest in the nuclear industry. It uses an optimal discretization scheme to carry out the numerical integration taking into account some useful characteristics of the still unknown posterior distribution. In some cases, the Bayesian update is performed analytically either by algebraic derivations or using the property of conjugation. The novel method is validated on practical industrial examples and benchmarked against Mathematica to prove its accuracy .
Bayesian approach in the power electric systems study of reliability
Synthese, 2017
This work aims to highlight prerogatives and advantages of the Bayesian approach in the reliability studies of the modern power electrical systems. The new organization of the electric energy sector and the consistent degree of technological innovation make the data more uncertain related to the operation of the electric systems components, with the consequent lack of information for an efficient estimation of the reliability according to the classical approach. Sometimes, this uncertainty concerns the same reliability models, missing adequately the validation of the model adaptations. In this paper, referring to the uncertainty of data, we define a general probabilistic model, for reliability studies. Subsequently, Bayesian methodologies are framed in an ampler problem list, based on the definition of an opportune "vector of state" and of a vector describing the system performances, aiming to the definition and the calculation or the estimation of system reliability. The ...
2009
This paper presents a model that can be implemented in a personal computer, which allows for the reliability analysis of safety systems of nuclear power plants, starting from a state transition diagram, typically employed in Markovian reliability analyses. Due to the need of considering the equipment qualified life extension, an issue of utmost importance in nuclear power plants nowadays, the classical Markovian model will not apply for at least one of the transition rates in the state transition diagram is generally time-dependent, due to equipment aging. To overcome this difficulty, the model is recast into a Markovian model by means of supplementary variables. As nuclear power plants are subject also to the so called maintenance rule, a requirement set up by the nuclear regulatory body, the utility needs to develop and present a maintenance program which is termed the Maintenance Effectiveness Monitoring Program in Brazil. The key feature here is the definition of maintenance pro...
IJRASET, 2021
Generating more Power are complex at cheaper cost, also continuous energy supplied are important Hydro power generation is one of the most successful renewable energy resources for the production electrical energy without any environmental hazard and presently it providing more than 86% of all electricity generated by renewable sources worldwide and accounts for about 20% of world electricity. To increase the percentage of green energy in account of world electricity generation the analysis must be performed to get the information about the working conditions of each component in plants so that the required maintenance action should be taken. Maintenance and operation of a hydro power plant is very complicated and the process to calculate and analyzing its compatibility and reliability is very important. In this work introducing a Markov model to evaluate the reliability parameter of THPS-I Sirmour, Rewa. For this work the operational data regarding failure and maintenance time taken to repaired and analysis of all parts of generating unit of the power plant for period of 2010-2015 is considered. The availability and reliability of individual unit of power plant is evaluated by taking into account different reliability Parameters, namely failure rate (λ), repair rate (µ), MTTR, MTTF, MTBF through the collected data and tabulating the required information for the analysis. By this analysis work we can improve reliability of all the components of each unit of power plant. The sub-unit that is commonly failed during operation is like-penstock, butter fly valve, spiral case, turbine, generator, excitation system, speed governor etc. Reliability plays a key role in the cost-effectiveness of systems