PSAM 16 Conference Paper Overview
Welcome to the PSAM 16 Conference paper and speaker overview page.
Lead Author: Richard Rolland Co-author(s): Raymond Schneider
schneire@westinghouse.com
| Lessons Learned in PRA Modeling of Digital Systems |
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| As the existing nuclear plant fleet ages and evolutionary plants are added to the nuclear plant generation capacity, analog safety systems that have been the mainstay of nuclear plant protection systems have started to become obsolete. These obsolescence issues are causing analog systems to be replaced with digital systems. The digital replacements offer several advantages over the analog counterparts including the ability to self-diagnose failures and place systems in safe-stable states. While these features increase the overall reliability of the system and reduce maintenance costs, they increase the complexity of the system. Digital systems still have the possibility of global failures of the digital safety function via common cause failure of software. It is helpful to build a PRA model for the digital system to fully understand the risk impact of the analog to digital transition. The complexity and relationships among the diverse and redundant system components introduces challenges to modeling of these systems. This paper discusses developing a digital I&C PRA model and explores the lessons learned in constructing digital I&C PRA models. Specifically, the paper focuses attention to the role of the failure mode and effects analyses, availability of detailed hardware and software failure data, the interaction of internal system diagnostics and human performance in system unavailability, potential treatment of environmental conditions, and considerations of uncertainty. Of particular importance, the paper discusses the potential treatment options for hardware and software related common cause failure. Based on a higher number of similar components within a digital system, the grouping of components to a single common cause failure scenario has increased compared to analog systems. Methods for appropriate modeling and for addressing challenges to common cause failures will be discussed. |
Paper RO150 Preview
Author and Presentation Info
Lead Author Name: Richard Rolland (ROLLANRW@WESTINGHOUSE.COM)
Bio: Richard Rolland is a Senior Engineer in Risk Analysis at Westinghouse Electric Company. During his time at Westinghouse, Richard has been involved in risk-informed applications, including the OEM lead for the 50.69 categorization core team, the 50.69 core team, and now the future risk-informed applications core team in the PWROG Risk Management Committee. Throughout his time at Westinghouse, Richard has also been involved in modeling of digital instrumentation and control systems (DI&C), including on work of developing lessons learned and best practices through PWROG projects. Richard has a nuclear engineering masters and bachelors degree from University of Wisconsin.
Country: United States of America
Company: Westinghouse Electric Company
Job Title: Senior Engineer
Bio: Richard Rolland is a Senior Engineer in Risk Analysis at Westinghouse Electric Company. During his time at Westinghouse, Richard has been involved in risk-informed applications, including the OEM lead for the 50.69 categorization core team, the 50.69 core team, and now the future risk-informed applications core team in the PWROG Risk Management Committee. Throughout his time at Westinghouse, Richard has also been involved in modeling of digital instrumentation and control systems (DI&C), including on work of developing lessons learned and best practices through PWROG projects. Richard has a nuclear engineering masters and bachelors degree from University of Wisconsin.
Country: United States of America
Company: Westinghouse Electric Company
Job Title: Senior Engineer