PSAM 16 - Session M05 Overview

PSAM 16 Conference Session M05 Overview

Session Chair: James Lin (jlin@absconsulting.com)

Paper 1 SU155

Lead Author: Sue Sallade Co-author(s): N. Reed LaBarge (labargnr@westinghouse.com) Alvin Robertson (robertac@westinghouse.com) Joe W. Loesch (joseph.w.loesch@xcelenergy.com) Jim M. Lynde (James.Lynde@exeloncorp.com) Kyle S. Shearer (sheareks@westinghouse.com) Laura L. Genutis (genutill@westinghouse.com)

Operational Guidance to Improve Industry Benefit of Alternate Equipment and Strategies
The PWROG has recently championed several efforts to increase collaboration between Probabilistic Risk Assessment (PRA) experts and nuclear power plant operators and procedure writers. The result of these efforts has allowed for nuclear power plants to risk inform plant procedures to reduce risk and promote the health and safety of the public. A key insight from this collaboration was the need for, and development of, an industry framework for generating written guidance to increase the benefit of alternate strategies. As the industry expands the use of alternate equipment (installed or portable), standardization of terminology, application, and PRA modeling of flexible equipment operation is desired. To that end, a new category of industry Guidelines has been defined: “Flex Support Guidelines Additional Defense in Depth” (FSG+DD). The new Guideline categorization maximizes the use of defense in depth and minimizes the need for flexible equipment to fall into regulatory required maintenance (Maintenance Rule Scope). FSG+DD strategies may be utilized to supplement current guidance used to maintain or restore a function when the plant is outside a Design Basis credited mitigating strategy. Additionally, these strategies may be utilized within a plant’s Design Basis to compensate for equipment that is inoperable and unavailable, or to maintain a function. This paper will discuss the Risk Informed Procedure Writers Guide developed by the PWROG to form the framework for the industry’s expanded use of flexible equipment.

Operational Guidance to Improve Industry Benefit of Alternate Equipment and Strategies

The PWROG has recently championed several efforts to increase collaboration between Probabilistic Risk Assessment (PRA) experts and nuclear power plant operators and procedure writers. The result of these efforts has allowed for nuclear power plants to risk inform plant procedures to reduce risk and promote the health and safety of the public. A key insight from this collaboration was the need for, and development of, an industry framework for generating written guidance to increase the benefit of alternate strategies. As the industry expands the use of alternate equipment (installed or portable), standardization of terminology, application, and PRA modeling of flexible equipment operation is desired. To that end, a new category of industry Guidelines has been defined: “Flex Support Guidelines Additional Defense in Depth” (FSG+DD). The new Guideline categorization maximizes the use of defense in depth and minimizes the need for flexible equipment to fall into regulatory required maintenance (Maintenance Rule Scope). FSG+DD strategies may be utilized to supplement current guidance used to maintain or restore a function when the plant is outside a Design Basis credited mitigating strategy. Additionally, these strategies may be utilized within a plant’s Design Basis to compensate for equipment that is inoperable and unavailable, or to maintain a function. This paper will discuss the Risk Informed Procedure Writers Guide developed by the PWROG to form the framework for the industry’s expanded use of flexible equipment.

Paper SU155 | Download the paper file. | Download the presentation PowerPoint file.

Name: Sue Sallade (sue.sallade@framatome.com)

Bio: 37 Years’ Experience in Nuclear Power Plant Operations and Training. Industry Expert in FLEX, PWR Emergency Procedures, Severe Accident Management, and Human Reliability Analysis Operational Assessments. As the Chairman of the PWROG Procedures Committee she participated in the development of the Generic Flex Support Guidelines and training for PWRs. As her sites Emergency Operating Procedures Owner she supervised the development of site specific FLEX response and training. She has been solicited as a FLEX Operational expert by the Nuclear Regulatory Commission, the Nuclear Energy Institute, Electric Power Research Institute, the American Nuclear Society, and the International Atomic Energy Association.

Country: USA
Company: Framatome
Job Title: Advisory Engineer

A PSAM Profile is not yet available for the presenter.

Paper 2 RO150

Lead Author: Richard Rolland Co-author(s): Raymond Schneider schneire@westinghouse.com

Lessons Learned in PRA Modeling of Digital Systems
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.

Lessons Learned in PRA Modeling of Digital Systems

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 | Download the paper file. | Download the presentation pdf file.

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: USA
Company: Westinghouse Electric Company
Job Title: Senior Engineer

Paper 3 LA154

Lead Author: N. Reed LaBarge Co-author(s): Jayne E. Ritter (jayne.e.ritter@xcelenergy.com) Roy Linthicum (roy.linthicum@exeloncorp.com) Kyle S. Shearer (sheareks@westinghouse.com) Damian Mirizio (mirizids@westinghouse.com)

Benefits and Lessons Learned from PRA / Operations Interface at Nuclear Power Plants
The PWROG has recently championed several efforts to increase collaboration between Probabilistic Risk Assessment (PRA) experts and nuclear power plant operators and procedure writers. The result of these efforts has been successful in promoting realism in the probabilistic representation of the role of human interface with nuclear power plants (i.e., Human Reliability Analysis (HRA)). Specifically a number of meetings and workshops have been held with PRA analysts, HRA experts and representatives from plant operations, procedure writing, and training to review current state-of-practice HRA methods and assumptions and identify areas that may be overly conservative. Guidance and recommendations have been developed and in some cases challenge state-of-practice HRA assumptions and methodologies. In these cases, specific methods or assumptions have been identified that could be revised to better reflect modern plant operational practices. Other areas of HRA have also be identified as opportunities for future research in order to ensure realistic treatment of the role of human operators on accident response. This paper intends to discuss several insights, best practices, operational improvements, and future research areas that have been recommended as a result these PWROG efforts.

Benefits and Lessons Learned from PRA / Operations Interface at Nuclear Power Plants

The PWROG has recently championed several efforts to increase collaboration between Probabilistic Risk Assessment (PRA) experts and nuclear power plant operators and procedure writers. The result of these efforts has been successful in promoting realism in the probabilistic representation of the role of human interface with nuclear power plants (i.e., Human Reliability Analysis (HRA)). Specifically a number of meetings and workshops have been held with PRA analysts, HRA experts and representatives from plant operations, procedure writing, and training to review current state-of-practice HRA methods and assumptions and identify areas that may be overly conservative. Guidance and recommendations have been developed and in some cases challenge state-of-practice HRA assumptions and methodologies. In these cases, specific methods or assumptions have been identified that could be revised to better reflect modern plant operational practices. Other areas of HRA have also be identified as opportunities for future research in order to ensure realistic treatment of the role of human operators on accident response. This paper intends to discuss several insights, best practices, operational improvements, and future research areas that have been recommended as a result these PWROG efforts.

Paper LA154 | Download the paper file. | Download the presentation PowerPoint file.

Name: N. Reed LaBarge (labargnr@westinghouse.com)

Bio: Fellow Engineer at Westinghouse Electric Company in the area of Probabilistic Risk Assessment, Level 2 PRA and Severe Accident Management Guidelines.

Country: USA
Company: Westinghouse Electric Company
Job Title: Fellow Engineer

Paper 4 RO194

Lead Author: Roy Linthicum Co-author(s): Mike Powell Michael.Powell@aps.com

Presenter of this paper: Michael Powell (michael.powell@aps.com)

Flex Equipment Reliability Data
Post Fukushima, Utilities have invested significant resources in procuring Flex Equipment and developing guidance for using the equipment for beyond design basis external hazards. NEI 16-08 “Guidance for Optimizing the Use of Portable Equipment” urges utilities to leverage this investment by using Flex or other portable equipment to provide additional safety benefits. These safety benefits can be quantified by including Flex equipment in the site-specific PRA models. This can provide additional margin for various risk informed applications, such as TSTF-505 “Provide Risk-Informed Extended Completion Times - RITSTF Initiative 4b”, Significance Determination Process evaluations and the Mitigating Systems Performance Index. Modeling Flex equipment in utility PRA models requires the development of reliability data, which is currently unavailable. The PWROG, with support form the BWROG, is currently developing failure data for the most commonly credited Flex equipment. This paper provides the final results of this evaluation including the approach used in developing the data, component boundaries, failure definitions and key sources of uncertainty, as well as the failure rates.

Flex Equipment Reliability Data

Post Fukushima, Utilities have invested significant resources in procuring Flex Equipment and developing guidance for using the equipment for beyond design basis external hazards. NEI 16-08 “Guidance for Optimizing the Use of Portable Equipment” urges utilities to leverage this investment by using Flex or other portable equipment to provide additional safety benefits. These safety benefits can be quantified by including Flex equipment in the site-specific PRA models. This can provide additional margin for various risk informed applications, such as TSTF-505 “Provide Risk-Informed Extended Completion Times - RITSTF Initiative 4b”, Significance Determination Process evaluations and the Mitigating Systems Performance Index. Modeling Flex equipment in utility PRA models requires the development of reliability data, which is currently unavailable. The PWROG, with support form the BWROG, is currently developing failure data for the most commonly credited Flex equipment. This paper provides the final results of this evaluation including the approach used in developing the data, component boundaries, failure definitions and key sources of uncertainty, as well as the failure rates.

Paper RO194 | Download the paper file. | Download the presentation PowerPoint file.

A PSAM Profile is not yet available for this author.
Presenter Name: Michael Powell (michael.powell@aps.com)

Bio: Michael (Mike) E. Powell is Director of Strategic Initiatives Palo Verde Generatino Station (Palo Verde) for Arizona Public Service Companv (APS), Powell ioined APS/Palo Verde in 1990. Powell has provided leadership to the US nuclear industry, He is currently the Chairman & Chief Operating Officer or the PWROG In roughly 32years at the site, Powell has held positions of increasing responsibility in various departments,including leadership roles in nuclear licensing, tire protection, nuclear projects, design engineering, maintenance engineering and nuclear fuel management. Powell has been a membership of Senior Leadership at the station since 2005. Powell has served as a Technical Consultant to the IAEA and is contributing author for several IAEA Technical Documents. Powell holds a bachelor's degree in electrical engineering from the State University of New York at Stony Brook and a master's degree in nuclear engineering from the Georgia Institute of Technology.

Country: United States of America
Company: Arizona Public Service Company (APS)/PWROG
Job Title: APS Director, Strategic Projects/ PWROG Chairman & Chief Operating Officer