PSAM 16 - Paper Overview

PSAM 16 Conference Paper Overview

Welcome to the PSAM 16 Conference paper and speaker overview page.

Lead Author: Fernando Ferrante Co-author(s): Karl Fleming, karlfleming@comcast.net Ed Parsley, eparsley@jensenhughes.com Charlie Young, cyoung@jensenhughes.com Leo Shanley, lshanley@jensenhughes.com

Enhancement of the Use of Defense-in-Depth and Safety Margin for Decision-Making Purposes
Both Defense-In-Depth (DID) and Safety Margin (SM) have been longstanding key concepts in nuclear applications, well before Probabilistic Risk Assessment (PRA) became a staple of risk applications in this field. A detailed review of key references on the subject of DID/SM in RIDM indicates that these topics are overdue for a more efficient, integrated approach, as RIDM applications continue to gain acceptance and implementation experience worldwide. As the use of PRA and RIDM continues to expand, different perspectives on DID/SM can challenge the incorporation of additional risk modeling and wider, more comprehensive application of PRA in nuclear power plants (NPPs). In particular, challenges from a deterministic-oriented perspective against more risk-informed applications, as well as their expansion in areas where PRA is not used as heavily, can lead to misperceptions that DID/SM principles are not aligned with respect to risk insights obtained via risk assessment inputs. A careful investigation and discussion of DID/SM as overarching principles of nuclear safety was performed to highlight that they are not intended to be substituted by PRA methods, tools, and results. Rather, the approach is to derive key elements of DID (i.e., design, programmatic, and scenario-based) that also accounted for SM inputs in a more logical, structured manner. A number of key conclusions were derived from this investigation, including the need for an enhanced, more efficient approach. Using key characteristics on how to treat DID/SM in RIDM, a recommended framework for an improvement implementation of DID/SM in RIDM is proposed, recognizing that DID/SM aspects are essential nuclear safety principles. As a different perspective than typically applied in current RIDM guidance, SM is identified as a fundamental input into the DID principle that can be better contextualized in RIDM as a supporting element (rather than a distinct and completely separate element). A significant discussion of how design, programmatic, and scenario-based DID aspects can be used in areas where PRA insights are already heavily used as well as in other areas not traditionally reliant on such inputs is discussed (including qualitative as well as quantitative risk inputs). A modern PRA model from an existing NPP site is used to showcase how risk insights on the achievement and preservation of DID/SM apply in the context of RIDM. The overall approach was based on leveraging existing guidance worldwide, considering approaches that appropriately bring the information together in a practical manner, as well as an investigation with actual implementable examples.

Enhancement of the Use of Defense-in-Depth and Safety Margin for Decision-Making Purposes

Both Defense-In-Depth (DID) and Safety Margin (SM) have been longstanding key concepts in nuclear applications, well before Probabilistic Risk Assessment (PRA) became a staple of risk applications in this field. A detailed review of key references on the subject of DID/SM in RIDM indicates that these topics are overdue for a more efficient, integrated approach, as RIDM applications continue to gain acceptance and implementation experience worldwide. As the use of PRA and RIDM continues to expand, different perspectives on DID/SM can challenge the incorporation of additional risk modeling and wider, more comprehensive application of PRA in nuclear power plants (NPPs). In particular, challenges from a deterministic-oriented perspective against more risk-informed applications, as well as their expansion in areas where PRA is not used as heavily, can lead to misperceptions that DID/SM principles are not aligned with respect to risk insights obtained via risk assessment inputs. A careful investigation and discussion of DID/SM as overarching principles of nuclear safety was performed to highlight that they are not intended to be substituted by PRA methods, tools, and results. Rather, the approach is to derive key elements of DID (i.e., design, programmatic, and scenario-based) that also accounted for SM inputs in a more logical, structured manner. A number of key conclusions were derived from this investigation, including the need for an enhanced, more efficient approach. Using key characteristics on how to treat DID/SM in RIDM, a recommended framework for an improvement implementation of DID/SM in RIDM is proposed, recognizing that DID/SM aspects are essential nuclear safety principles. As a different perspective than typically applied in current RIDM guidance, SM is identified as a fundamental input into the DID principle that can be better contextualized in RIDM as a supporting element (rather than a distinct and completely separate element). A significant discussion of how design, programmatic, and scenario-based DID aspects can be used in areas where PRA insights are already heavily used as well as in other areas not traditionally reliant on such inputs is discussed (including qualitative as well as quantitative risk inputs). A modern PRA model from an existing NPP site is used to showcase how risk insights on the achievement and preservation of DID/SM apply in the context of RIDM. The overall approach was based on leveraging existing guidance worldwide, considering approaches that appropriately bring the information together in a practical manner, as well as an investigation with actual implementable examples.

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Author and Presentation Info

Lead Author Name: Fernando Ferrante (fferrante@epri.com)

Bio: Fernando Ferrante is a Principal Project Manager at the Electric Power Research Institute (EPRI) in the Risk and Safety Management group (RSM). Ferrante joined EPRI in 2017 as a Principal Technical Leader in RSM. He was promoted to Principal Project Manager within RSM in March 2021, gaining responsibility for direct oversight of RSM staff involved in human reliability, fire risk assessment, external flooding PRA, along with RIDM framework activities. Dr. Ferrante held positions as a risk analyst at the U.S. Nuclear Regulatory Commission and senior engineer at the Defense Nuclear Facilities Safety Board. Dr. Ferrante holds a Bachelor of Science degree in Mechanical Engineering from University College London, in the United Kingdom, and a Doctor of Philosophy degree in Civil Engineering from Johns Hopkins University.

Country: ---
Company: Electric Power Research Institute
Job Title: Program Manager

PSAM 16 Conference Paper Overview

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