PSAM 16 Conference Paper Overview
Welcome to the PSAM 16 Conference paper and speaker overview page.
Lead Author: Jan Stiller
| Modelling and Quantification of Correlated Failures of Multiple Components due to Asymmetries of the Electrical Power Supply System of Nuclear Power Plants in PSA |
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| Failures of multiple redundant trains of the electrical power supply system of nuclear power plants (NPPs) have recently gained increasing attention by the nuclear community. This was triggered by events at different NPPs where single causes led to such failures. For example, at the Byron NPP (USA), asymmetries in the power supply system arose from a single failure of an insulator in the switchyard of the plant. The asymmetry failed to cause the reactor protection system (RPS) to initiate the isolation of the emergency bus bars and the operation of the emergency diesel generators. At the Forsmark NPP (Sweden), an open phase condition which was not detected by the RPS was caused by the failure of one pole of a breaker. In both events, the electrical consumers remained connected with the fault and were exposed to an asymmetric voltage supply, leading to unavailability and destruction of safety related electrical equipment. Similar events occurred in other plants as well, e.g., at Vandellòs, Unit 2 (Spain) in 2006, at Dungeness, Unit B (United Kingdom) in 2007 and at Bruce, Unit A-1 (Canada) in 2012. To consider such events in PSA, the failures of electrical components due to asymmetries in the electrical power supply system have to be adequately modelled and quantified. A comprehensive analysis of international operating experience regarding asymmetries in the electrical power supply has shown that resulting component failures cannot be modelled as independent events but are significantly correlated. Similar components with comparable loads tend to fail simultaneously. This is very important to safety since redundant components are likely to be affected by such correlated failures. To grasp this effect, different modelling approaches have been considered. Estimation algorithms for the respective model parameters have been developed and applied utilizing the international operating experience. The paper will present the analysis of the operating experience, the modelling approaches and first quantification results. |
Paper SJ53 Preview
Author and Presentation Info
Lead Author Name: Jan Stiller (sjc@grs.de)
Bio: Jan Stiller studied Physics and has a PhD in Theoretical physics. After different postoc positions with a focus an Bayesian statistical methods and machine learning he joined GRS in 2003, where he currently is the chief expert equipment reliability. Main topics of his work are common-cause failure modelling and quantification, quantification of the reliability of software based digital I&C, organizational factors and (safety) management.
Country: Germany
Company: Gesellschaft für Anlagen- und Reaktorsicherheit (GRS) gGmbH
Job Title: Chief expert equipment reliability
Bio: Jan Stiller studied Physics and has a PhD in Theoretical physics. After different postoc positions with a focus an Bayesian statistical methods and machine learning he joined GRS in 2003, where he currently is the chief expert equipment reliability. Main topics of his work are common-cause failure modelling and quantification, quantification of the reliability of software based digital I&C, organizational factors and (safety) management.
Country: Germany
Company: Gesellschaft für Anlagen- und Reaktorsicherheit (GRS) gGmbH
Job Title: Chief expert equipment reliability