Marked point process framework for living probabilistic safety assessment and risk follow-up

Arjas, Elja; Holmberg, Jan-Erik

doi:10.1016/0951-8320(95)00030-6

Cited by 14 publications

(7 citation statements)

References 7 publications

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“…PRA models use a static estimate for event probability and POF, typically based on historical observations and engineering judgment. More recently, time-based POF values derived from operating experience and traditional reliability analysis have been used (Vesely and Wolford 1988;Arjas and Holmberg 1995); however, these are usually not specific to the component. Ramuhalli et al (2013b) discuss the potential for integrating predicted POF values from PHM systems with risk monitors to obtain a realistic assessment of dynamic risk that is unit-specific and accounts for the operational history of the component.…”

Section: Phm Risk Monitors and Plant Control Technologiesmentioning

confidence: 99%

Local-Level Prognostics Health Management Systems Framework for Passive AdvSMR Components. Interim Report

Ramuhalli

Roy

Hirt

et al. 2014

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Section: Phm Risk Monitors and Plant Control Technologiesmentioning

confidence: 99%

Local-Level Prognostics Health Management Systems Framework for Passive AdvSMR Components. Interim Report

Ramuhalli

Roy

Hirt

et al. 2014

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“…In general, PRA models use a static estimate for event probability and POF, typically based on historic observations and engineering judgment. More recently, time-based POF values have been used (Vesely and Wolford 1988;Arjas and Holmberg 1995); however, these are derived from operating experience and traditional reliability analysis and are usually not specific to the operating component.…”

Section: Pra Models and Techniquesmentioning

confidence: 99%

Technical Report on Preliminary Methodology for Enhancing Risk Monitors with Integrated Equipment Condition Assessment

Ramuhalli¹,

Coles²,

Coble³

et al. 2013

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Executive SummaryAdvanced small modular reactors (AdvSMRs) may provide a longer-term alternative to traditional light-water reactors and SMRs based on integral pressurized water reactor concepts currently being considered. AdvSMRs are designed to incorporate multiple modules (which may or may not have shared components and structures) at a single location, comprising a full "plant." AdvSMR operation differs fundamentally from full-size plants because the smaller plants may be used for load-following or peakdemand power generation, instead of baseload generation. AdvSMRs are also being considered for dualuse, where process heat would be used for both electricity generation and another purpose such as hydrogen production or water desalination, shown in Figure Enhancing affordability of AdvSMRs will be critical to ensuring wider deployment. Although some of the loss of economies of scale inherent to AdvSMRs can be recovered, controllable day-to-day costs of AdvSMRs will be dominated by operation and maintenance (O&M) costs.Technologies that help characterize real-time risk are important to controlling O&M costs and improving affordability of AdvSMRs. Given the possibility of frequently changing plant configurations in AdvSMRs, advanced plant configuration information, equipment condition information, and risk monitors are needed to support real-time decisions on O&M. For this purpose, approaches are needed to integrate these three elements in a manner that provides a measure of risk that is customized for each AdvSMR unit, and accounts for the specific operational history of the unit. By integrating technologies for condition assessment with risk monitors, asset optimization and improved economics of AdvSMRs may be enabled by:• Maximizing generation by assessing the potential impact of taking key components offline for testing or maintenance, iv• Supporting reduced O&M staff by aiding in optimization of O&M planning (specifically by assessing the contribution of individual components to changes in risk and using this information for scheduling maintenance activities),• Enabling real-time decisions on stress-relief for risk-significant equipment susceptible to degradation and damage, and• Supporting potential remote siting by providing early warning of potential increases in plant risk.This report describes research results from an initial methodology for such enhanced risk monitors (ERMs) that integrate real-time information about equipment condition and probability of failure (POF) into risk monitors to provide an assessment of dynamic risk as plant equipment ages. This integration occurs at the level of the POF within risk monitors.Risk monitors extend probabilistic risk assessment (PRA) frameworks by incorporating the actual and dynamic plant configuration (e.g., equipment availability, operating regimes, and environmental conditions) into the risk assessment. PRA is itself a systematic safety analysis methodology that follows four steps: identify undesirable consequences (e.g., reactor unavailability, core da...

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“…These methods do not take into account the current condition of the components, and are susceptible to error in probabilistic estimates. More recently, time-based POF values have been used (Vesely and Wolford 1988;Arjas and Holmberg 1995); however, these are derived from operating experience and traditional reliability analysis and are usually not specific to the operating component.…”

Section: Probabilistic Risk Assessment (Pra)mentioning

confidence: 99%

“…In their use of real-time component condition, ERM technologies differ from conventional risk monitors (Wu and Apostolakis 1992;Kafka 2008) that use a static estimate for event probability and POF, typically based on historical observations and engineering judgment. More recently, time-based POF values derived from operating experience and traditional reliability analysis have been used (Vesely and Wolford 1988;Arjas and Holmberg 1995); however, these are usually not specific to the component. Critical to the ERMs is a predictive estimate of POF of the component, which is precisely what PHM provides (Coble et al 2012).…”

Section: Benefits Of Prototypic Enhanced Risk Monitoring Technologiesmentioning

confidence: 99%

Prototypic Enhanced Risk Monitor Framework and Evaluation - Advanced Reactor Technology Milestone: M3AT-15PN2301054

Ramuhalli¹,

Hirt²,

Veeramany³

et al. 2015

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Enabling real-time decisions on stress-relief for risk-significant equipment susceptible to degradation and damage, thereby supporting optimized lifetime management. As described in previous reports in this series, probabilistic risk assessment (PRA) provides a static representation of risk associated with operation and maintenance (O&M) of nuclear power plants. Technologies for characterizing real-time risk (so called Enhanced Risk Monitors or ERMs) take into account plant-specific normal, abnormal, and deteriorating states of systems, structures, and components (SSCs) in the estimation of current and future risk to safe and economic operation. Additionally, technologies for characterizing real-time risk provide a mechanism for compensating for the relatively small amount of long-term reliability data from AR systems, structures, and components. The ability to monitor performance and characterize changes in operational risk in real-time can reduce the level of dependence on such performance data. Proactively establishing a viable ERM methodology before AR component design specifications are established also supports: (i) building in opportunities for automated monitoring (on-line and off-line) of those components for optimizing performance with respect to anticipated demands on these reactors; and (ii) improving the maintainability of components from the perspective of time-to-repair and component cost. This research report summaries the development and evaluation of a prototypic ERM methodology (framework) that includes alternative risk metrics and uncertainty analysis. This updated ERM methodology accounts for uncertainty in the equipment condition assessment (ECA), the prognostic result, and the PRA model. It is anticipated that the ability to characterize uncertainty in the estimated risk and update the risk estimates in real-time based on ECA will provide a mechanism for optimizing plant performance while staying within specified safety margins. The report provides an overview of the methodology for integrating time-dependent failure probabilities into risk monitors. This prototypic ERM methodology was evaluated using a hypothetical PRA model, generated using a simplified design of a liquid-metal-cooled AR. Component failure data from industry compilation of failures of components similar to those in the simplified AR model were used to initialize the PRA model. By using time-dependent probability of failure (POF) that grows from the initial probability when equipment is in like-new condition to a maximum POF, which occurs before a scheduled maintenance action that restores or repairs the component to "as-new" condition, the changes in core damage frequency (CDF) over time were computed and analyzed. vii Acronyms and Abbreviations AC alternating current AdvSMR advanced small modular reactor AFI aging fractional increase AST aging start time CAFTA Computer Aided Fault Tree Analysis (system) CCF common cause failure CDF core damage frequency CREDO Centralized Reliability Data Organization (component reliabili...

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Marked point process framework for living probabilistic safety assessment and risk follow-up

Cited by 14 publications

References 7 publications

Local-Level Prognostics Health Management Systems Framework for Passive AdvSMR Components. Interim Report

Local-Level Prognostics Health Management Systems Framework for Passive AdvSMR Components. Interim Report

Technical Report on Preliminary Methodology for Enhancing Risk Monitors with Integrated Equipment Condition Assessment

Prototypic Enhanced Risk Monitor Framework and Evaluation - Advanced Reactor Technology Milestone: M3AT-15PN2301054

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