ML18082A108

Summary of February 28, 2018, Meeting with Duke Energy Carolinas, LLC to Discuss Proposed LAR Regarding Tornado Mitigation Licensing Basis

ML18082A108
Person / Time
Site:	Oconee
Issue date:	03/29/2018
From:	Audrey Klett Plant Licensing Branch II
To:	Batson S Duke Energy Carolinas
Klett, Audrey
References
EPID L-2018-LRM-0003
Download: ML18082A108 (29)

Text

UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555..0001 March 29, 2018 LICENSEE: Duke Energy Carolinas, LLC FACILITY: Oconee Nuclear Station, Units 1, 2, and 3

SUMMARY

OF FEBRUARY 28, 2018, MEETING WITH DUKE ENERGY CAROLINAS, LLC TO DISCUSS PROPOSED LICENSE AMENDMENT REQUEST FOR OCONEE NUCLEAR STATION, UNITS 1, 2, AND 3 REGARDING TORNADO MITIGATION LICENSING BASIS (EPID L-2018-LRM-0003)

On February 28, 2018, the U.S. Nuclear Regulatory Commission (NRC) staff held a Category 1 public meeting with representatives from Duke Energy Carolinas, LLC (the licensee) at NRC Headquarters, One White Flint North, 11555 Rockville Pike, Rockville, Maryland. The purpose of the meeting was to discuss a proposed license amendment request (LAR) to clarify and change the tornado mitigation licensing basis for the Oconee Nuclear Station, Units 1, 2, and 3 (Oconee). The meeting notice and agenda, dated February 12, 2018, are available in NRC's Agencywide Documents Access and Management System under Accession No. ML18043A574. A list of attendees and the meeting presentation material are enclosed.

The licensee presented background material for its planned LAR to modify the Oconee Updated Final Safety Analysis Report (UFSAR) related to tornado mitigation. Enclosure 2 of this meeting summary contains the presentation slides that the licensee provided to the NRC staff. The licensee intends to have multiple public meetings, as necessary, with the staff before it submits its LAR, which it plans to do in August 2018. The licensee stated that it intends the planned LAR to supersede its previous LAR, for which the NRC suspended its review.

The licensee gave the staff a presentation of the purpose of the planned submittal and described its assumptions used in analyses and the plant's design features for mitigating a tornado. The licensee stated that it completed a comprehensive review of its tornado licensing basis. The licensee plans to credit the standby shutdown facility (SSF) as the deterministically protected path for tornado mitigation within a 72-hour mission time and use TORMIS as an acceptable method for evaluating systems and components necessary for the SSF to fulfill its credited mission that are not physically protected from tornado induced missiles. The licensee plans to eliminate reliance on other redundant and diverse systems that are not fully protected from a tornado; however, these systems would still be used for defense-in-depth. The licensee's analysis assumes that a tornado significantly damages one unit with all units experiencing a loss of all alternating current electrical power. The licensee plans to use a new application of previously-approved thermal hydraulic methodologies for evaluating reactor coolant system conditions after a tornado. The licensee does not plan to install main steam

isolation valves. The licensee plans to credit completed modifications and discussed future modifications for which it is not seeking NRC prior approval.

The NRC staff asked the licensee questions about the assumed tornado paths and operator actions during a tornado. The staff asked if the pressurizer would go water-solid. The licensee responded that the level might go off-scale high but does not go water solid. The Reactor Coolant pressure would remain below the safety limit, and operators would respond to that as though the pressurizer was water-solid. The staff also asked the licensee if the missile list in the UFSAR would be affected and whether there were any overlaps with high energy line break analyses. The staff asked whether there were any cross-ties between the units for tornado mitigation. The licensee responded that cross-ties are not credited in the new strategy but are credited in probabilistic risk analyses. The staff stated that the application should clearly state what is changing in the licensing basis and what has already been approved. The staff asked the licensee whether the application would be dependent or linked to any other applications that the staff is currently reviewing (e.g., LAR 2017-03). The licensee indicated that it would not be linked. The staff asked if structures such as the reactor and auxiliary buildings would be re-evaluated, and the licensee indicated that they would not be re-evaluated. After the meeting, the licensee provided the NRC licensing project manager with a document containing NRC questions and licensee answers. This document is enclosed.

The staff did not make any regulatory decisions or commitments at the meeting. No members of the public were in attendance at the meeting nor announced over the telephone.

Any inquiries can be directed to me at 301-415-0489 or via e-mail at Audrey.Klett@nrc.gov.

d--------

Audrey L. Klett, Project Manager Plant Licensing Branch 11-1 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket Nos. 50-269, 50-270, and 50-287

Enclosures:

1. List of Attendees

2. Licensee Documentation of Questions and Answers

3. Meeting Presentation Material Cc: Listserv

Enclosure 1 List of Attendees

LIST OF ATTENDEES FEBRUARY 28, 2018, MEETING WITH DUKE ENERGY CAROLINAS, LLC OCONEE NUCLEAR STATION, UNITS 1. 2, AND 3 PROPOSED LICENSE AMENDMENT REQUEST REGARDING TORNADO MITIGATION LICENSING BASIS U.S. Nuclear Regulatory Commission Michael Markley Robert Beaton Olivier Lareynie Robert Pettis Stewart Bailey Gordon Curran Mike Breach Shavon Morris Robert Dennig Audrey Klett Duke Energy Carolinas, LLC Timothy Brown Chris Wasik Philip North Dave Baxter Jason Patterson Lee Kanipe Reene Gambrell Tracy Saville*

Greg Byers*

Mark Handrick*

Scott Thomas*

Eric Henshaw*

• Participated by phone

Enclosure 2 Licensee Documentation of Questions and Answers

NRC Tornado License Amendment Request (LAR) Meeting 2/28/18 Duke Responses to NRC Questions

1. The NRR Staff asked if we could package the Tornado LAR into separate LARs specifically requesting what we wanted NRC review and approval (e.g. separate LAR addressing TORM IS, another addressing Safety Analysis methodology and acceptance criteria, etc.).

Duke Response: After review, we believe one comprehensive LAR would prove to be the easiest to review and track. The proposed strategy largely depends on NRC review and approval of the TORM IS analysis and the Safety Analysis methodology/acceptance criteria. If these elements were submitted in separate LARs, difficulties could ensue if the review and approval of one of the LARs is ahead of the second LAR, such that overall approval of strategy could become complicated. Duke proposes to subdivide the one comprehensive LAR into attachments, with one attachment addressing TORM IS and another attachment addressing the Safety Analysis methodology/acceptance criteria. This approach could allow the NRR to divide their reviewers amongst those separate attachments.

2. NRR staff member Bob Dennig asked a question on the scope of systems and components included in the TORM IS analysis; - Why not include Emergency Feedwater (EFW) and Protected Service Water (PSW) systems into the model as well as the Standby Shutdown Facility (SSF) related components?

Duke Response: The proposed strategy and supporting analyses assume that the EFW/PSW systems are not available since they are not completely protected from the effects of a tornado. We believe this assumption to be conservative. The intent of the strategy is to demonstrate that the SSF and its pathway to the units would survive the tornado, due to (1) SSF being designed for the effects of tornado, including 360 miles per hour wind, a pressure differential of 3 psi, and substantial array of missiles defined in the Oconee Updated Final Safety Analysis Report (UFSAR) Table 9-17, and (2)

TORM IS analysis showing that missile strikes on the SSF connection(s) in the West Penetration Room (WPR) and Cask Decontamination Tank Room (CDTR) and other supporting equipment are remote and meet the acceptance criteria stipulated in Standard Review Plan (SRP) sections 3.5.1.4 and 3.5.2.

3. A NRR reviewer asked if we had planned to include in the LAR the rationale for not installing Main Steam Isolation Valves (MSIVs). Another comment suggested that the proposed LAR should not include a roadmap of the changes or a comparison to the 2008 LAR.

Duke Response: The current licensing basis does not include the MSIVs. The proposed tornado mitigation strategy also does not include MSIVs. Although the 2008 Tornado LAR did commit to the installation of MSIVs, the review of which was suspended, the proposed LAR to be submitted later this year will completely supersede the 2008 LAR. In lieu of providing the rationale for not installing MSIV into the proposed LAR (which is the principal difference in the 2008 LAR and the proposed LAR), we propose adding the appropriate documents that provides the rationale into a web based viewing room that the NRR reviewers could access.

Enclosure 3 Meeting Presentation Material

Oconee Nuclear Station Tornado License Amendment Pre-Submittal Meeting One White Flint, Rockville, MD February 28, 2018

Agenda Duke Attendees:

David A. Baxter (Dave), ONS Regulatory Projects Christopher J. Wasik (Chris), ONS Regulatory Affairs Timothy D. Brown (Tim), ONS Regulatory Projects Jason A. Patterson (Jason), ONS Regulatory Projects Philip J. North (Phil), ONS Regulatory Projects C. Reene Gambrell (Reene), ONS Regulatory Projects Lee M. Kanipe, Jr. (Lee), Fleet Probabilistic Risk Analysis Michael E. Henshaw (Eric), Fleet Safety Analysis 2

Agenda Opening Remarks Oconee Tornado Current Licensing Basis (CLB) 2015-06 Regulatory Information Summary (RIS) 2018 Tornado License Amendment Request (LAR)

Closing Remarks 3

Opening Remarks To clarify the Tornado Licensing Basis, ONS intends to submit a License Amendment that will seek NRC review and approval of the following:

Establishment of initial condition of loss of all AC power to all units with significant tornado damage to one unit.

Establishment of Standby Shutdown Facility (SSF) as assured tornado mitigation path.

Elimination of reliance on redundant and diverse system(s) and component(s) that are not fully protected from tornadoes.

New application of previously approved thermal hydraulic methodologies (UFSAR Chapter 6 LOCA modeling) for evaluating conditions in the RCS following the tornado.

Establishes success criteria for RCS conditions following a tornado.

Application of TORMIS to evaluate SSF support systems and components that are not physically protected for tornado missiles.

4

Tornado CLB Tornado is not defined as a design basis event.

In the original licensing of the plant, no event analysis for tornado was completed and no safe shutdown sequences were determined.

Protection from the effects of a tornado is established as a design criterion for select Systems, Structures, and Components (SSCs).

Physical Tornado Protection of Class 1 Structures (e.g. Reactor Building, and portions of the Auxiliary Building) is provided.

Redundancy, Diversity, and Physical Separation credited to assure:

Source of Power and associated pathway to the unit.

Source of Secondary Side Decay Heat Removal and associated pathway to the unit.

Source of Primary Makeup and associated pathway to the unit.

5

Tornado CLB Keowee Hydroelectric KHS Overhead Path Major Site Emergency, SSF, & PSW Station (KHS)

Power Paths 525kV 230kV Switchyard Switchyard Overhead to the Units (typ) KHS Underground Power Path to PSW KHS Underground Units 1 & 2 Unit 3 Blockhouse Power Path to CT-4 Blockhouse Protected PSW Underground/

CT-4 Blockhouse Above Ground Turbine Building Power Path to Unit Specific Components PSW Transformer &

Auxiliary Building Switchgear Building CT-5 Path to U1 RB U2 RB U3 RB Standby Bus of all Tie to Units Grid PSW Underground Power to SSF 100 to N

13.8kV Substation Standby Shutdown Facility SSF Underground Tie to Lee Power Path to Unit CT-5 Combustion Specific (Outside) Turbines Components 6

Tornado CLB Diverse sources of power:

230kV / 525kV switchyard.

Keowee Hydro Station (KHS) underground path to CT-4.

KHS overhead path through the Startup Transformers.

KHS Station underground path to Protected Service Water (PSW) Switchgear Building.

Commercial path to PSW Switchgear Building.

Commercial path from Lee Combustion Turbines (LCT) to CT-5.

Standby Shutdown Facility (SSF) Diesel Generator (DG) pathway via underground trenches to the respective units.

PSW power alignment to the SSF (defense in depth).

7

Tornado CLB Diverse supply of secondary side cooling water via:

Main Feedwater/Condensate from Main Condenser.

Emergency Feedwater (EFW) from Condensate Upper Surge Tank and Main Condenser Hotwell.

EFW from other unit(s) through cross-connects.

PSW (formerly the Station Auxiliary Service Water System) from the buried Condenser Circulating Water (CCW) piping.

SSF Auxiliary Service Water (ASW) from the buried CCW piping.

Note: HPI forced cooling can be used as a substitute for secondary side decay heat removal.

8

Tornado CLB Primary Makeup:

High Pressure Injection (HPI) Pumps from the Borated Water Storage Tank(s)

(BWST) or Spent Fuel Pool(s).

SSF Reactor Coolant Makeup (RCMU) from the Spent Fuel Pool(s).

9

2015-06 RIS Activities Completed comprehensive review of Tornado CLB.

Completed survey of station structures, systems, and components (SSC) that could be used to mitigate a tornado.

Two non-conformances with the tornado design criterion were discovered that have been corrected.

Enforcement discretion was not submitted.

10

Proposed 2018 Tornado LAR Proposed LAR supersedes LAR submitted in 2008.

Credits the SSF as the one deterministically protected path for tornado mitigation within its 72 hour8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> mission time:

Source of emergency power from the SSF Diesel Generator.

Source of secondary side makeup to the steam generators from the SSF ASW System.

Source of primary makeup to the reactor coolant system from the SSF RCMU System.

11

Proposed 2018 Tornado LAR Tornado significantly damages one unit, with the other units experiencing a loss of all AC power.

Eliminates reliance on other redundant and diverse system(s) that are not fully protected from tornado.

New application of previously approved thermal hydraulic methodologies (UFSAR Chapter 6 LOCA modeling) for evaluating conditions in the RCS following the tornado.

12

Proposed 2018 Tornado LAR Thermal hydraulic success criterion for the RCS following a tornado:

Main Feedwater Line Breaks (overheating events): RCS pressure < 2750 psig, allowance for water solid operations without water relief through the Pressurizer code safety valves.

Main Steam Line Breaks (overcooling events): Core remains covered and in a cool-able geometry, departure from nucleate boiling ratio remains within limits.

Eliminates the need to install Main Steam Isolation Valves (MSIVs).

Implementation of TORMIS as an acceptable method for evaluating systems and components necessary for the SSF to fulfill its credited mission that are not physically protected from tornado induced missiles.

13

Proposed 2018 Tornado LAR 14

Proposed 2018 Tornado LAR 15

Proposed 2018 Tornado LAR 16

Proposed 2018 Tornado LAR Credits completed modifications:

Protection of BWST for tornado wind and missiles.

Protection against wind loads and P using Fiber Reinforced Polymer (FRP) on the West Penetration Rooms (WPRs) and Cask Decontamination Tank Rooms (CDTRs).

Protection of SSF south side double doors for tornado missiles.

Protection from tornado missile impacts through the SSF south side personnel access stairwell on the SSF ASW lines.

Protection from tornado missiles through miscellaneous SSF exterior penetrations.

Protection of SSF north end cable trench cover and SSF trench crossover of CT-5 trench for tornado missiles .

Protection of SSF Diesel Service Water discharge piping for tornado missiles.

Protection of SSF Diesel Fuel Oil Tank Vent for tornado missiles.

17

Proposed 2018 Tornado LAR Future SSF enhancements:

Enhanced SSF system instrumentation, including:

Individual Steam Generator Pressure.

Core Exit Thermocouples.

Wide Range Neutron Flux.

Pressurizer Temperature.

SSF ASW system fine feed control to each units steam generator.

Does not seek NRC review and approval of these modifications (they will be evaluated via 50.59).

18

Proposed 2018 Tornado LAR Licensing Document Changes Significant rewrite of UFSAR description of tornado mitigation:

Establishment of initial condition of loss of all AC power to all units with significant tornado damage to one unit.

Establishment of Standby Shutdown Facility (SSF) as assured tornado mitigation path.

Elimination of reliance on redundant and diverse system(s) and component(s) that are not fully protected from tornadoes.

New application of previously approved thermal hydraulic methodologies (UFSAR Chapter 6 LOCA modeling) for evaluating conditions in the RCS following the tornado.

Establishes success criteria for RCS conditions following a tornado.

Application of TORMIS to evaluate SSF support systems and components that are not physically protected for tornado missiles.

No anticipated changes to Technical Specifications.

19

Closing Remarks ONS intends to submit a License Amendment that will significantly change the stations tornado licensing basis.

The LAR will seek NRC review and approval of the following:

Establishment of initial condition of loss of all AC power to all units with significant tornado damage to one unit.

Establishment of Standby Shutdown Facility (SSF) as assured tornado mitigation path.

Elimination of reliance on redundant and diverse system(s) and component(s) that are not fully protected from tornadoes.

New application of previously approved thermal hydraulic methodologies (UFSAR Chapter 6 LOCA modeling) for evaluating conditions in the RCS following the tornado.

Establishes success criteria for RCS conditions following a tornado.

Application of TORMIS to evaluate SSF support systems and components that are not physically protected for tornado missiles.

20

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SUMMARY

OF FEBRUARY 28, 2018, MEETING WITH DUKE ENERGY CAROLINAS, LLC TO DISCUSS PROPOSED LICENSE AMENDMENT REQUEST FOR OCONEE NUCLEAR STATION, UNITS 1, 2, AND 3 REGARDING TORNADO MITIGATION LICENSING BASIS (EPID L-2018-LRM-0003) DATED MARCH 29, 2018 DISTRIBUTION:

PUBLIC LPL2-1 R/F RidsACRS_MailCTR Resource RidsNrrDorllpl2-1 Resource RidsNrrDorlDpr Resource RidsRgn2MailCenter Resource RidsNrrPMOconee Resource RidsNrrLAKGoldstein Resource RidsNrrDeEseb Resource RidsNrrDeEmib Resource RidsNrrDeEeob Resource RidsNrrDssSrxb Resource RidsNrrDssSbpb Resource R. Beaton, NRR/DSS R. Pettis, NRR/DE G. Curran, NRR/DSS M. Breach, NRR/DE S. Morris, NRR/DE P. Sahay, NRR/DE ADAMS Access1on No.: ML18082A108 *b1yema1*1 OFFICE NRR/DORL/LPL2-1 /PM NRR/DORL/LPL2-1 /LA NRR/DSS/SBPB/BC*

NAME AKlett KGoldstein RDennig DATE 03/23/18 03/23/18 03/28/18 OFFICE NRR/DSS/SRXB/BC (A)* NRR/DE/ESEB/BC* NRR/DE/EEOB/BC*

NAME JWhitman BWittick (RPettis for) JQuichocho DATE 03/29/18 03/23/18 03/28/18 OFFICE NRR/DE/EMIB/BC* NRR/DORL/LPL2-1 /BC NRR/DORL/LPL2-1 /PM NAME SBailey MMarkley (MMahoney for) AKlett DATE 03/29/18 03/29/18 03/29/18 OFFICIAL RECORD COPY