ML21316A225
| ML21316A225 | |
| Person / Time | |
|---|---|
| Issue date: | 11/23/2021 |
| From: | Siva Lingam, Michael Montecalvo NRC/NRR/DORL/LPL4, NRC/NRR/DRA/APOB |
| To: | Jennifer Whitman NRC/NRR/DRA/APLB |
| Lingam S | |
| References | |
| EPID L-2021-NFO-0007 | |
| Download: ML21316A225 (11) | |
Text
November 23, 2021
MEMORANDUM TO: Jennifer Whitman, Chief PRA Licensing Branch B Division of Risk Assessment Office of Nuclear Reactor Regulation
FROM: Siva P. Lingam, Project Manager /RA/
Plant Licensing Branch IV Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation
Michael Montecalvo, Senior Reactor Analyst /RA/
PRA Oversight Branch Division of Risk Assessment Office of Nuclear Reactor Regulation
SUBJECT:
SUMMARY
OF OCTOBER 20, 2021, PUBLIC WORKSHOP WITH NUCLEAR ENERGY INSTITUTE, INDUSTRY, AND ELECTRIC POWER RESEARCH INSTITUTE TO PROVIDE AN UPDATE ON STAFF AND EPRI ACTIVITIES ASSOCIATED WITH THE HIGH ENERGY ARCING FAULTS INVOLVING ALUMINUM (EPID L-2021-NFO-0007)
On October 20, 2021, the U.S. Nuclear Regulatory Commission (NRC) staff held a Category 3 public meeting with Nuclear Energy Institute (NEI), Industry, and Electric Power Research Institute (EPRI) to provide a status and update on NRC and EPRI activities related to the potential safety-significance of aluminum high energy arcing faults (Al HEAF), and to achieve an understanding of NEI, Industry, and EPRI perspectives related to this topic. Additionally, this meeting was conducted to explain the use of the Office of Nuclear Reactor Regulation (NRR)
Office Instruction LIC-504, Integrated Risk-Informed Decisionmaking Process for Emergent Issues, to apply best available information and NRC risk assessment tools to determine whether any regulatory actions associated with potential safety-significance of Al HEAF should be considered to enhance public safety. The meeting notice and agenda, dated September 28, 2021, are available in the Agencywide Documents Access and Management System (ADAMS) under Accession No. ML21288A082. A list of attendees is provided in.
The slides presented for this public meeting are available in ADAMS under Accession Nos. ML21291A179 and ML21293A007. A list of the panel members representing NRC, EPRI, NEI, Duke-Energy, and Gesellschaft für Anlagen-and Reaktorsicherheit (GRS) mbH of Germany is included in Enclosure 2. A list of presenters is included in Enclosure 3. The meeting included a facilitated discussion between the panel members regarding relevant operating experience events, thus achieving the goal of the panel discussion. These discussions enabled the representatives to understand the varying views among key
J. Whitman
stakeholders on how the presence of Al could in lead to an increase in the risk from a HEAF event. During the meeting, the NRC staff in formed the industry that the LIC-504 analyses use best available information to perform a realistic analysis of risk, and that industrys ability to share information could enhance the staffs ability to generate recommendations that are commensurate with the risk significance. Some members of industry indicated a willingness to provide NRC with current probabilistic risk asse ssment information to support more realistic NRC staff assessments associated with NRR Office Instruction LIC-504. The details of the meeting are discussed in Enclosure 4.
No comments were provided by members of the public. No regulatory decisions or commitments were made at the meeting.
Please direct any inquiries to me at (301) 415-1564 or by e-mail at Siva.Lingam@nrc.gov, or Michael Montecalvo at (301) 415-1678 or by e-mail at Michael.Montecalvo@nrc.gov.
Enclosures:
- 1. List of Attendees
- 2. List of Panel Members
- 3. List of Presenters
- 4. Meeting Details
LIST OF ATTENDEES
OCTOBER 20, 2021, PUBLIC MEETING WITH
NUCLEAR ENERGY INSTITUTE, INDUSTRY, AND
ELECTRIC POWER RESEARCH INSTITUTE
TO PROVIDE AN UPDATE ON STAFF AND EPRI ACTIVITIES ASSOCIATED WITH
HIGH ENERGY ARCING FAULTS INVOLVING ALUMINUM
Christian Araguas U.S. Nuclear Regulatory Commission (NRC)
Scott Burnell NRC Stephanie Coffin NRC Glenn Dentel NRC Mike Franovich NRC Stanley Gardocki NRC Kenneth Hamburger NRC John Hughey NRC Matthew Humberstone NRC J.S. Hyslop NRC Meena Khanna NRC Andrea Kock NRC Robert Krsek NRC Siva Lingam NRC Sarah Lopas NRC David Loveless NRC Michael Mahoney NRC Nick Melly NRC Michael Montecalvo NRC Angel Moreno NRC Charles Moulton NRC Tony Nakanishi NRC Ching Ng NRC Lundy Pressley NRC Reinaldo Rodriguez NRC Andy Rosebrook NRC MarkHenry Salley NRC Neil Sheehan NRC Muzzamil Siddiqui NRC David Stroup NRC Mark Thaggard NRC Edgardo Torres NRC Shilp Vasavada NRC Sunil Weerakkody NRC Jennifer Whitman NRC Antonios Zoulis NRC
Enclosure 1
Dr. Marina Rwekamp Gesellschaft für Anlagen-and Reaktorsicherheit (GRS) gGmbH, Germany Ashley Lindman Electric Power Research Institute (EPRI)
Ferrante Fernando EPRI Marko Randjelovic EPRI Thomas Short EPRI Tina Taylor EPRI Kelli Voelsing EPRI Mark Woodby EPRI Victoria Anderson Nuclear Energy Institute (NEI)
Andrew Mauer NEI Brett Titus NEI Jennifer Uhle NEI Jeffrey Ertman Duke-Energy Jack Lemmer Duke-Energy Robert Rishel Duke-Energy Greg Norris Entergy Jeffrey Stone Exelon Anthony Putorti National Institute of Standards and Technology Wayne Harper Energy Northwest Trevor McLaen Energy Northwest Chris LaFleur Sandia National Laboratories Austin Michael Glover Sandia National Laboratories Young Jo Southern Nuclear Company Brian Krystek Engineering Planning and Management, Inc. (EPM)
Travis Weber EPM Matti Lehto STUK International, Finland Rodney Pletz Unknown Jason Floyd Jensen Hughes Victor Ontiveros Jensen Hughes Chico Pellizari EPM Robert Rhodes Unknown Steve Turner Consultant Andy Zach U.S. Senate Environment and Public Works Committee
Note: Several personnel from the Industry also attended (not able to capture the names by phone numbers in the Microsoft Teams).
LIST OF PANEL MEMBERS
OCTOBER 20, 2021, PUBLIC MEETING WITH
NUCLEAR ENERGY INSTITUTE, INDUSTRY, AND
ELECTRIC POWER RESEARCH INSTITUTE
TO PROVIDE AN UPDATE ON STAFF AND EPRI ACTIVITIES ASSOCIATED WITH
HIGH ENERGY ARCING FAULTS INVOLVING ALUMINUM
Victoria Anderson Nuclear Energy Institute Mike Franovich U.S. Nuclear Regulatory Commission (NRC)
Nick Melly NRC Robert Rishel Duke Energy Dr. Marina Rwekamp Gesellschaft für Anlagen-and Reaktorsicherheit (GRS) gGmbH, Germany Kelli Voelsing Electric Power Research Institute
Enclosure 2 LIST OF PRESENTERS
OCTOBER 20, 2021, PUBLIC MEETING WITH
NUCLEAR ENERGY INSTITUTE, INDUSTRY, AND
ELECTRIC POWER RESEARCH INSTITUTE
TO PROVIDE AN UPDATE ON STAFF AND EPRI ACTIVITIES ASSOCIATED WITH
HIGH ENERGY ARCING FAULTS INVOLVING ALUMINUM
Victoria Anderson Nuclear Energy Institute Kenneth Hamburger U.S. Nuclear Regulatory Commission (NRC)
Nick Melly NRC Michael Montecalvo NRC Robert Rishel Duke Energy Dr. Marina Rwekamp Gesellschaft für Anlagen-and Reaktorsicherheit (GRS) gGmbH, Germany Kelli Voelsing Electric Power Research Institute Sunil Weerakkody NRC
Enclosure 3 MEETING DETAILS
OCTOBER 20, 2021, PUBLIC MEETING WITH
NUCLEAR ENERGY INSTITUTE, INDUSTRY, AND
ELECTRIC POWER RESEARCH INSTITUTE
TO PROVIDE AN UPDATE ON STAFF AND EPRI ACTIVITIES ASSOCIATED WITH
HIGH ENERGY ARCING FAULTS INVOLVING ALUMINUM
Purpose
The purpose of this public workshop between the U.S. Nuclear Regulatory Commission (NRC) staff, the Nuclear Energy Institute (NEI), Industry, and the Electric Power Research Institute (EPRI) was to provide a status and update on NRC and EPRI activities related to the potential safety-significance of aluminum high energy arcing faults (Al HEAF), and to achieve an understanding of NEI, Industry, and EPRI perspectives related to this topic. Additionally, this meeting was conducted to explain the use of th e Office of Nuclear Reactor Regulation (NRR)
Office Instruction LIC-504, Integrated Risk-Informed Decisionmaking Process for Emergent Issues (Agencywide Documents Access and Management System (ADAMS) Accession No. ML19253D401), to apply best available information and NRC risk assessment tools to determine whether any regulatory actions should be considered regarding the potential safety-significance of Al HEAF to enhance public safety.
=
Background===
Insights from review of U.S operating experience (NRC Information Notice 2017-04, High Energy Arcing Faults in Electrical Equipment Containing Aluminum Components, dated August 21, 2017 (ADAMS Accession No. ML17058A343) and an international collaborative research program identified that Al HEAFs may release more energy than expected and assumed in the current fire probabilistic risk assessment (PRA) methodology. Subsequent NRC testing provided additional information and insigh ts to characterize the hazard. The NRC used a modified Institute of Electrical and Electronic Engineers 1584 methodology to develop a preliminary revised zone of influence (ZOI) for the Al HEAF hazard, which indicated that the revised ZOI may be larger than the ZOI in the current fire PRA methodology in some fire scenarios. The risk impact from the fire scenarios with increased ZOIs will be configuration based and plant specific.
As described in its August 21, 2021, memo (ADAMS Accession No. ML21237A360), the NRC has exited the Generic Issues Program for Al HEAFs and entered into a regulatory process consistent with NRR Office Instruction LIC-504. The revised approach supports a more efficient resolution of the issue using a risk-informed process and aligns with the Be RiskSMART framework. As stated above, the LIC-504 evaluation will use the best available HEAF technical information, along with available plant information.
The NRC staff has reviewed additional informati on from the ongoing RES testing, operating experience, and collaborative research with EPRI. After considering this additional information, the staff continues to believe that the increased ZOI of the AL HEAF hazard, in some scenarios,
Enclosure 4
does not constitute an immediate safety conc ern that warrants prompt regulatory action (ADAMS Accession No. ML21272A262).
The NRC staff will continue to work with EPRI under the memorandum of understanding on Fire Research to advance the state of knowledge for evaluating A HEAFs in PRAs.
The NRC staff will assess if any longer-term regu latory actions are justified based on the detailed LIC-504 evaluation.
NRC Observations of the Workshop
The agenda included a facilitated panel that included the NRC, an international expert, NEI, EPRI, and a member of industry speaking on operating experience related to HEAF as well as an update from the NRC staff on the risk-informed process we are using to evaluate the issue.
The workshop had a large number of participants, including numerous members of industry and several public stakeholders. There were no comments or questions from members of the public at the end of the meeting.
The intended purposes of the workshop, which were to facilitate a better understanding of the perspectives and interpretation of the operating experience and to convey the status of our efforts, were achieved.
The NRC staff emphasized that the agency has not taken positions on how plant operating experience may affect previous estimates of ZOIs as a result of Al HEAF. The staff has not made any conclusions at this time, and have reaffirmed that there is no need for any prompt regulatory actions.
Based on the EPRI Industry survey and analysis of U.S. plants, there appears to be a small subset of plants that Al-HEAF may pose a risk concern. The staff does not know the identities of these plants (https://www.epri.com/research/programs/061177/results/3002020692).
It is not possible or appropriate to draw definitive conclusions from single specific events (increased risk or not) based on limited information and different plant configurations.
The NRC staff clarified that we are not using specific events alone or information in isolation to conclude the need for any regulatory action. Rather, the staff is using insights from operating experience and testing to refine the approaches and considerations taken, thus far, as part of its evaluation.
While there was a diversity of views regarding the potential increased risk associated with Al HEAF, participants came away with a better understanding of these perspectives and the reasons behind them.
The NRC staff provided an overview of the LIC-504 process and how it will allow NRC to move forward in an expeditious and risk-informed manner.
Meeting Details
The panel members provided the following presentations:
Kelli Voelsing of EPRI concluded her presentation with the following highlights:
Aluminum exists in all U.S. plants and in many components.
Detailed survey results on the location and types of structures, systems, and components (SSCs) containing Al provide valuable information for the purpose of informing NRC RES proposed testing on HEAFs.
The presence of Al is not directly related to increased risk.
Actual changes in plant risk from Al involved in HEAFs cannot be determined until realistic ZOIs are determined and applied with the newly developed fire PRA modeling guidance for HEAFs.
The EPRI bounding assessment using the current fire PRA data and draft methodology provide high confidence that for a large portion of the U.S. plants, the presence of Al would likely have limited impact.
Dr. Marina Rowekamp of Gesellschaft für Anlagen-and Reaktorsicherheit (GRS) gGmbH, Germany, and Senior member of the Organization for Economic Co-operation and Development/Nuclear Energy Agency Fire Incidents Records Exchange (OECD/NEA FIRE) database and HEAF projects, addressed HEAF events that occurred in the early 2000s at Maanshan (Taiwan) and in 2011 at Onagawa (Japan). She also provided international insights from HEAF operating experience with the following highlights:
The OECD/NEA FIRE database is a collection of fire events in nuclear power plants of 14 countries from Asia, Europe, and North America.
Operating experience indicates significance of HEAF as an important phenomenon for causing ensuing fires at the component where the HEAF occurred, but also as an event combination with other events.
HEAF needs to be considered in design and operation of nuclear installations.
Victoria Anderson of NEI provided NEIs perspectives on HEAF stating that Al HEAF is not a safety concern based on robust cables, 100,000s of component operating years with aluminum widespread, and no increased ZOI noted with operating experience.
Robert Rishel of Duke Energy presented Shearon Harris and Robinson operating experience expressing that ZOI damage was less than predicted by current guidance, damage to SSCs was limited to the associated cabinet/enclosure, and a nearby cable tray was degraded but remained functional.
Nick Melly of NRC/RES shared the operating expe rience describing the events at Fort Calhoun, Unit 1; Columbia; Diablo Canyon, Unit 1; Kewaunee, Unit 1; and Shearon Harris, Unit 1. Panel members and others discussed these events and provided their views.
After panel members presentations, Kenneth Hamburger of NRC/RES updated the NRC/EPRI Working Group (WG) activities as noted below:
Characterize the primary factors that influence the occurrence and severity of arcing fault events (arc flash, arc blast, or HEAF)
Develop tools and methods to assess the risk posed by arcing fault events based on experimental data, operating experience, and engineering judgment
Mr. Hamburger also summarized the WG deliverables and schedule to be completed by summer 2022.
Sunil Weerakkody and Michael Montecalvo of NRC/NRR explained the NRR LIC-504 process and the state of progress of its assessment, citing examples of recommendations from recent LIC-504 assessments.
Stephanie Coffin, Deputy Director for RES and Andrea Kock Deputy Director for NRR provided opening and closing remarks respectively, emphasizing that this public workshop was held to hear the opinions from various related organizations and present the NRC perspectives on the ongoing risk evaluation of Al HEAF and reiterated a few of the key messages conveyed in the NRC Observations, above.
Packages: ML21291A179 and ML21293A007 Meeting Notice: ML21039A199 Meeting Slides: ML21291A180, ML21291A181, ML21291A182, ML21291A183 ML21291A184 (non-public), ML21291A185, ML21293A009, and ML21293A008 Meeting Summary: ML21316A225 *by e-mail OFFICE NRR/DORL/LPL4/PM* NRR/DRA/APOB/RA* NRR/DORL/LPL4/LA*
NAME SLingam MMontecalvo PBlechman
DATE 10/25/21 10/28/21 11/16/21
OFFICE RES/DRA/FXHAB/BC* NRR/DRA/APLB/BC NRR/DORL/LPL4/PM*
NAME MSalley JWhitman SLingam DATE 11/18/21 11/23/21 11/23/21