ML16327A494

Interim Staff Response to Reevaluated Flood Hazards Submitted in Response to 10 CFR 50.54(f) Information Request - Flood-Causing Mechanism Reevaluation (CAC Nos. MF8379 and MF8380)

ML16327A494
Person / Time
Site:	Arkansas Nuclear
Issue date:	12/02/2016
From:	Robert Bernardo Japan Lessons-Learned Division
To:	Entergy Operations
Bernardo P, NRR/JLD, 415-2621
Shared Package
ML16327A482	List: ML16327A494 ML16327A530
References
CAC MF8379, CAC MF8380
Download: ML16327A494 (9)

Text

OFFICIAL USE ONLY-SECURITY RELATED INFORMATION UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-0001 December 2, 2016 Vice President, Operations Arkansas Nuclear One Entergy Operations, Inc.

1448 S.R. 333 Russellville, AR 72802

SUBJECT:

ARKANSAS NUCLEAR ONE, UNITS 1AND2- INTERIM STAFF RESPONSE TO REEVALUATED FLOOD HAZARDS SUBMITTED IN RESPONSE TO 10 CFR 50.54(f) INFORMATION REQUEST - FLOOD-CAUSING MECHANISM REEVALUATION (CAC NOS. MF8379 AND MF8380)

Dear Sir or Madam:

The purpose of this letter is to provide a summary of the U.S. Nuclear Regulatory Commission (NRC) staff's assessment of the reevaluated flood-causing mechanisms described in the September 14, 2016, flood hazard reevaluation report (FHRR) submitted by Entergy Operations, Inc. (Entergy, the licensee) for Arkansas Nuclear One, Units 1 and 2 (ANO)

(Agencywide Documents Access and Management System (ADAMS) Accession No. ML16260A060).

By letter dated March 12, 2012, the NRC issued a request for information pursuant to Title 10 of the Code of Federal Regulations, Section 50.54(f) (hereafter referred to as the 50.54(f) letter)

(ADAMS Accession No. ML12053A340). The request was issued as part of implementing lessons learned from the accident at the Fukushima Dai-ichi nuclear power plant. Enclosure 2 to the 50.54(f) letter requested that licensees reevaluate flood-causing mechanisms using present-day methodologies and guidance. Concurrent with the reevaluation of flooding hazards, licensees were required to develop and implement mitigating strategies in accordance with NRC Order EA-12-049, "Requirements for Mitigation Strategies for Beyond-Design-Basis External Events" (ADAMS Accession No. ML12054A735). On March 30, 2015, the Commission provided staff requirements memorandum (SRM) (ADAMS Accession No. ML15089A236) to COMSECY-14-0037, "Integration of Mitigating Strategies for Beyond-Design-Basis External Events and the Reevaluation of Flooding Hazards," dated November 21 , 2014 (ADAMS Accession No. ML14309A256), affirming that licensees need to address the reevaluated flooding hazards within their mitigating strategies for beyond-design-basis external events.

Enclosure 2 transmitted herewith contains Security-Related Information. When separated from the Enclosure, this document is decontrolled.

OFFICIAL USE ONLY - SECURITY RELATED INFORMATION

OFFICIAL USE ONLY-SECURITY RELATED INFORMATION The NRC staff has reviewed the information submitted by the licensee and has summarized the results of the review in the tables provided as an enclosure to this letter. Table 1 provides the current design-basis flood hazard mechanisms. Table 2 provides the reevaluated flood hazard mechanisms; however, the reevaluated flood hazard mechanisms bounded by the current design-basis (Table \,) are not included. Because Table 1 includes security-related information, contains the redacted version of Table 1. Enclosure 2 is withheld from public disclosure and restores the security-related information to Table 1.

The NRC staff has concluded that the licensee's reevaluated flood hazard information, as summarized in the enclosure, is suitable for the assessment of mitigating strategies developed in response to Order EA-12-049 (i.e., defines the mitigating strategies flood hazard information described in Nuclear Energy Institute (NEI) guidance document NEI 12-06, "Diverse and Flexible Coping Strategies (FLEX) Implementation Guide") for ANO. Further, the NRC staff has concluded that the licensee's reevaluated flood hazard information is a suitable input for other assessments associated with Near-Term Task Force Recommendation 2.1, "Flooding." The NRC staff plans to issue a staff assessment documenting the basis for these conclusions at a later time.

Revision 2 of NEI 12-06 includes a methodology to perform a mitigating strategies assessment (MSA) with respect to the reevaluated flood hazards. On February 29, 2016, the NRC staff published Japan Lessons-Learned Division (JLD) Interim Staff Guidance (ISG)

JLD-ISG-2012-01 , Revision 1, "Compliance with Order EA-12-049, Order Modifying Licenses with Regard to Requirements for Mitigation Strategies for Beyond-Design-Basis External Events" (ADAMS Accession No. ML15357A142) in the Federal Register (81 FR 10283). This ISG endorses Revision 2 of NEI 12-06 (ADAMS Accession No. ML16005A625), dated December 2015. Based on the guidance provided in Revision 2 of NEI 12-06, flood event duration parameters and applicable flood associated effects should be considered as part of the ANO MSA. The NRC staff will evaluate the flood event duration parameters (including warning time and period of inundation) and flood-related associated effects developed by the licensee during the NRC staff's review of the MSA.

As stated above, Table 2 of the enclosure to this letter describes the reevaluated flood hazards that exceed the current design basis. In order to complete its response to the information requested by Enclosure 2 to the 50.54(f) letter, the licensee is expected to submit an integrated assessment or a focused evaluation, as appropriate, to address these reevaluated flood hazards, as described in the NRC letter, "Coordination of Request for Information Regarding Flooding Hazard Reevaluation and Mitigating Strategies for Beyond-Design-Basis External Events" (ADAMS Accession No. ML15174A257). This letter describes the changes in the NRC's approach to the flood hazard reevaluations that were approved by the Commission in its SRM to COMSECY-15-0019, "Closure Plan for the Reevaluation of Flooding Hazards for Operating Nuclear Power Plants" (ADAMS Accession No. ML15209A682).

OFFICIAL USE ONLY-SECURITY RELATED INFORMATION

OFFICIAL USE ONLY - SECURITY RELATED INFORMATION If you have any questions, please contact me at (301) 415-22621 or e-mail at Robert.Bernardo@nrc.gov.

Sincerely, a~~t Manager Hazards Management Branch Japan Lessons-Learned Division Office of Nuclear Reactor Regulation Docket Nos. 50-313 and 50-368

Enclosures:

1) Summary of Results of Flooding Hazard Re-Evaluation Report (Redacted Version)

2) Summary of Results of Flooding Hazard Re-Evaluation Report (Non-Public Version) cc w/encl: Distribution via Listserv OFFICIAL USE ONLY - SECURITY RELATED INFORMATION

ENCLOSURE 1:

SUMMARY

TABLES OF REEVALUATED FLOOD HAZARD LEVELS-REDACTED VERSION

Arkansas Nuclear One, Units 1 & 2 Table 1. Current Design Basis Flood Hazards for Use in the MSA Mechanism I Stillwater Waves/ Design Basis I Reference I I Elevation Runup Hazard I Elevation Local Intense Precipitation I

Not included Not included Not included FHRR Table 4-1 in DB in DB in DB Streams and Rivers PMF on Arkansas River 358.0 ft, I 10.0 ft 368.0 ft, FHRR Table 4-1 NGVD29 NGVD29

[REDACTED] [REDACTED] [REDACTED] [REDACTED] [REDACTED]

I Failure of Dams and Onsite Water Control/Storage Structures I Not included Not included Not included FHRR Table 4-1 in DB in DB in DB Storm Surge Not included Not included Not included FHRR Table 4-1 in DB in DB in DB Seiche Not included Not included Not included FHRR Table 4-1 in DB in DB in DB I

Tsunami Not included Not included Not included FHRR Table 4-1 in DB in DB in DB I

I Ice-Induced Flooding Not included I Not included Not included FHRR Table 4-1 in DB in DB in DB I I

Arkansas Nuclear One, Units 1 & 2 Table 1. Current Design Basis Flood Hazards for Use in the MSA Mechanism Stillwater Waves/ Design Basis Reference I Elevation Runup Hazard Elevation I Channel Migrations/Diversions I Not included Not included Not included FHRR Table 4-1 in DB in DB in DB I

Note 1: Reported values are rounded to the nearest one-tenth of a foot.

Arkansas Nuclear One, Units 1 & 2 Table 2. Reevaluated Flood Hazards for Flood-Causing Mechanisms for Use in the MSA Mechanism Stillwater Waves/ Reevaluated Reference Elevation Run up Hazard I Elevation Local Intense Precipitation North Train Bay Door 354.4 ft, Minimal 354.4 ft, FHRR Table 4-2 NGVD29 NGVD29 South Train Bay Door 354.4 ft, Minimal 354.4 ft, FHRR Table 4-2 NGVD29 NGVD29 Between Warehouse and 355.0 ft, Minimal 355.0 ft, FHRR Table 4-2 Reactor Building Unit 2 NGVD29 NGVD29 West of Maintenance Building 353.7 ft, Minimal 353.7 ft, FHRR Table 4-2 NGVD29 NGVD29 North of Turbine Building Unit 2 353.7 ft, Minimal 353.7 ft, FHRR Table 4-2 NGVD29 NGVD29 South of Turbine Building Unit 2 355.1 ft, Minimal 355.1 ft, FHRR Table 4-2 NGVD29 NGVD29 South of Central Support Building 354.0 ft, Minimal 354.0 ft, FHRR Table 4-2 NGVD29 NGVD29 North of Central Support Building 357.7 ft, Minimal 357.7 ft, FHRR Table 4-2 NGVD29 NGVD29 Northeast of Turbine Building 354.4 ft, Minimal 354.4 ft, FHRR Table 4-2 Unit2 NGVD29 NGVD29 Transformer Yard 354.4 ft, Minimal 354.4 ft, FHRR Table 4-2 NGVD29 NGVD29 East of Turbine Building Unit 1 354.3 ft, Minimal 354.3 ft, FHRR Table 4-2 NGVD29 NGVD29

A rkansas Nuclear One, Units 1 & 2 Table 2. Reevaluated Flood Hazards for Flood-Causing Mechanisms for Use in the MSA I

Mechanism Stillwater Waves/ Reevaluated Reference Elevation Runup Hazard Elevation Northwest of Intake Structure 354.1 ft, Minimal 354.1 ft, FHRR Table 4-2 NGVD29 NGVD29 North of Intake Structure 354.2 ft, Minimal 354.2 ft, FHRR Table 4-2 I NGVD29 NGVD29 North of ISFSI 356.3 ft, Minimal 356.3 ft, FHRR Table 4-2 NGVD29 NGVD29 South of ISFSI 355.6 ft, Minimal 355.6 ft, FHRR Table 4-2 NGVD29 NGVD29 East of Cooling Tower 351.4 ft, Minimal 351 .4 ft, FHRR Table 4-2 NGVD29 NGVD29 West of Warehouse 351.2 ft, Minimal 351 .2 ft, FHRR Table 4-2 NGVD29 NGVD29 South of Warehouse 351.4ft, Minimal 351.4 ft, FHRR Table 4-2 NGVD29 NGVD29 I West of Diesel Oil Storage Tank 354.5 ft, Minimal 354.5 ft, FHRR Table 4-2 NGVD29 NGVD29 I West of Engineering/Modification 352.2 ft, Minimal 352.2 ft, FHRR Table 4-2 Building NGVD29 NGVD29 Between 352.7 ft, Minimal 352.7 ft, FHRR Table 4-2 Engineering/Modification Building NGVD29 NGVD29 and Reactor Building 1 East of Diesel Fuel Storage Vault 353.7 ft, Minimal 353.7 ft, FHRR Table 4-2 NGVD29 NGVD29 Note 1: Reevaluated hazard mechanisms bounded by the current design basis (see Table 1) are not included in this table Note 2: Reported values are rounded to the nearest one-tenth of a foot.

OFFICIAL USE ONLY - SECURITY RELATED INFORMATION If you have any questions, please contact me at (301) 415-22621 or e-mail at Robert.Bernardo@nrc.gov.

Sincerely, IRA/

Robert Bernardo, Project Manager Hazards Management Branch Japan Lessons-Learned Division Office of Nuclear Reactor Regulation Docket Nos. 50-313 and 50-368

Enclosures:

1) Summary of Results of Flooding Hazard Re-Evaluation Report (Redacted Version)

2) Summary of Results of Flooding Hazard Re-Evaluation Report (Non-Public Version) cc w/encl : Distribution via Listserv DISTRIBUTION:

PUBLIC JLD R/F RidsNRRJLD Resource RBernardo, NRA LQuinn-Willingham, NAO RidsNroDsea Resource RidsNrrDorllpl4-2 Resource RidsNrrDorl Resource RidsNrrPMANO Resou rce RidsRgn4MailCenter Resource RidsNrrLASLent RidsOgcMailCenter Resource RidsOpaMail Resource RidsAcrsAcnw_MailCtr Resource CCook, NAO MBensi, NAO KErwin , NAO ACampbell, NAO MWillingham, NAO KSee , NAO BHarvey, NAO MShams, NRA GBowman, NR ADAMS Accession Nos.: PKG ML16327A482 LTR: ML16327A494 ENCL 1: ML16327A530 (PUBLIC)

ENCL 2ML16327A503 (NON-PUBLIC)

• via email OFFICE NRR/JLD/JHMB/PM NRR/JLD/LA NRO/DSEA/RHM1 /TR*

NAME A Bernardo Slent KSee*

DATE 11 /22/201 6 11 /28/2016 11 /15/201 6 OFFICE NRO/DSEA/RHM1 /BC* NRR/JLD/JHMB/BC NRR/JLD/JHMB/PM NAME CCook GBowman A Bernardo DATE 11 / 15/2016 11 /29/2016 12/2/2016 OFFICIAL AGENCY RECORD OFFICIAL USE ONLY-SECURITY RELATED INFORMATION