ML16090A327

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Interim Staff Response to Reevaluated Flood Hazards Submitted in Response to 10 CFR 50.54(f) Information Request - Flood-Causing Mechanism Reevaluation
ML16090A327
Person / Time
Site: Waterford 
Issue date: 04/12/2016
From: Victor Hall
Japan Lessons-Learned Division
To:
Entergy Operations
HALL V, NRR/JLD, 415-2915
Shared Package
ML16090A313 List:
References
CAC MF7125
Download: ML16090A327 (5)
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Text

Site Vice President UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-0001 April 12, 2016 Entergy Operations, Inc.

Waterford Steam Electric Station, Unit 3 17265 River Road Killona, LA 70057-3093

SUBJECT:

WATERFORD STEAM ELECTRIC STATION, UNIT 3 - INTERIM STAFF RESPONSE TO REEVALUATED FLOOD HAZARDS SUBMITTED IN RESPONSE TO 10 CFR 50.54(f) INFORMATION REQUEST-FLOOD-CAUSING MECHANISM REEVALUATION (CAC NO. MF7125)

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 July 21, 2015 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML15204A321 ), flood hazard reevaluation report (FHRR) submitted by Entergy Operations, Inc. (Entergy, the licensee) for Waterford Steam Electric Station, Unit 3 (Waterford), as well as supplemental information resulting from requests for additional information and audits.

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 licensees to re-evaluate flood-causing mechanisms using present-day methodologies and guidance. Concurrently 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 Memoranda (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.

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 1) are not included.

The NRC staff has concluded that the licensee's reevaluated flood hazards 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 Waterford, Unit 3. 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 the NEI 12-06 guidance document, flood event duration parameters and applicable flood associated effects should be considered as part of the Waterford, Unit 3 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).

If you have any questions, please contact me at (301) 415-2915 or e-mail at Victor.Hall@mc.gov.

Docket No. 50-382

Enclosure:

Summary of Results of Flooding Hazard Re-Evaluation Report cc w/encl: Distribution via Listserv Sincerely,

{;,{'- [ liJ Victor Hall, Senior Project Manager Hazards Management Branch Japan Lessons-Learned Division Office of Nuclear Reactor Regulation

ENCLOSURE:

SUMMARY

TABLES OF REEVALUATED FLOOD HAZARD LEVELS

Waterford Steam Electric Station, Unit 3 Table 1. Current Design Basis Flood Hazards for Use in the MSA Mechanism Stillwater Waves/

Design Basis Reference Elevation Run up Hazard Elevation Local Intense Precipitation Nuclear Plant Island Structure 1.6 ft Depth Minimal 1.6 ft Depth FHRR Sections 2.2, 2.3.1, & Table 4-1 Internal Ponding Depth at Dry Cooling Tower Streams and Rivers Probable Maximum Flood on 27.0 ft MSL Not 27.0 ft MSL FHRR Section 2.3.1 & Table 4-1 Mississippi River applicable Combined Event: Probable 27.6 ft MSL Not 27.6 ft MSL FHRR Sections 2.2, 2.3.1 & Table 4-1 Maximum Flood and Probable applicable Maximum Hurricane coincident with a levee failure at the Mississippi River Failure of Dams and Onsite Water Control/Storage Structures Probable Upstream Dam No Impact No Impact No Impact FHRR Section 2.3.1 & Table 4-1 Failures - Seismically Induced on the Site on the Site on the Site Identified Identified Identified Storm Surge Probable Maximum Storm Surge 18.1 ft MSL 5.6 ft 23.7 ft MSL FHRR Section 2.3.1 & Table 4-1 from Gulf of Mexico FSAR (Rev. 13) Section 2.4 Seiche No Impact No Impact No Impact FHRR Section 2.3.1 & Table 4-1 on the Site on the Site on the Site Identified Identified Identified Tsunami No Impact No Impact No Impact FHRR Section 2.3.1 & Table 4-1 on the Site on the Site on the Site Identified Identified Identified Ice-Induced Flooding No Impact No Impact No Impact FHRR Section 2.3.1 & Table 4-1 on the Site on the Site on the Site Identified Identified Identified 1

Waterford Steam Electric Station, Unit 3 Table 1. Current Design Basis Flood Hazards for Use in the MSA

~-

--~-

Mechanism Stillwater Waves/

Design Basis Reference Elevation Run up Hazard Elevation Channel Migrations/Diversions Cooling Water Canals No Impact No Impact No Impact FHRR Section 2.3.1 & Table 4-1 on the Site on the Site on the Site Identified Identified Identified Note 1: Reported values are rounded to the nearest one-tenth of a foot.

Note 2: For flooding hazards within the Nuclear Plant Island Structure (NPIS), the licensee reported some flooding hazard levels in terms of ponding depth rather than water surface elevation. The NRC staff accepted the licensee's convention and present this information in terms of ponding depth, where applicable.

2

Waterford Steam Electric Station, Unit 3 Table 2. Reevaluated Flood Hazards for Flood-Causing Mechanisms for Use in the MSA Mechanism Stillwater Waves/

Reevaluated Reference I

I Elevation Run up Hazard I

Elevation Local Intense Precipitation Waterford Steam Electric Station 20.5 ft MSL Minimal 20.5 ft MSL FHRR 3.1.1.2.4 & Table 4-1 Yard (Outside of Nuclear Plant Island Structure)

Local Intense Precipitation in Dry 1.6 ft Depth Minimal 1.6 ft Depth FHRR Section 3.1.3 & Table 4-1 Cooling Tower Basins (Ponding)

Streams and Rivers Probable Maximum Flood on 29.9 ft MSL Not 29.9 ft MSL FHRR Section 3.2.3 & Table 4-1 Mississippi River applicable Failure of Dams and Onsite Water Control/Storage Structures Probable Maximum Flood +

29.9 ft MSL Not 29.9 ft MSL FHRR Section 3.3.2 & Table 4-1 Hypothetical Dam Break within applicable the Mississippi River Probable Maximum Flood +

20.6 ft MSL Not 20.6 ft MSL FHRR Section 3.3.2 & Table 4-1 Hypothetical Dam Break at applicable WSES Site Probable Maximum Flood +

22.8 ft MSL 4.9 ft 27.7 ft MSL FHRR Section 3.9.3.1 & Tables 3-30 Hypothetical Dam Break within

& 3-31 the Mississippi River and Levee Failure (Scenario H.1 at East NPIS)

Probable Maximum Flood + SSE 20.8 ft MSL Not 20.8 ft MSL FHRR Section 3.9.3.2 & Table 3-31 Seismic Dam Failure, Levee applicable Failure, and Induced Wind Waves (Scenario H.2 for Northwest NPIS)

Probable Maximum Flood + SSE 18.9 ft MSL 1.9 ft 20.8 ft MSL FHRR Section 3.9.3.2 & Table 3-31 Seismic Dam Failure, Levee Failure, and Induced Wind Waves (Scenario H.2 for East NPIS) 1

Waterford Steam Electric Station, Unit 3 Table 2. Reevaluated Flood Hazards for Flood-Causing Mechanisms for Use in the MSA Mechanism Stillwater Waves/

Reevaluated Reference Elevation Run up Hazard Elevation Storm Surge Probable Maximum Storm Surge 21.6 ft MSL Not 21.6 ft MSL FHRR Section 3.4.5 & Table 4-1 from Gulf of Mexico at WSES applicable Combined Event H.3 (Alternative 26.0 ft MSL 5.8 ft 31.8 ft MSL FHRR Sections 3.9.3.3 & 3.9.4 &

3): 25-Year Flood in the Table 4-1 Mississippi River, Probable Maximum Storm Surge Including Antecedent Water Level, Levee Failure, and Coincident Wind-Generated Waves at Site Note 1: The licensee is expected to develop flood event duration parameters and applicable flood associated effects to conduct the MSA. The staff will evaluate the flood event duration parameters (including warning time and period of inundation) and flood associated effects during its review of the MSA.

Note 2: Reevaluated hazard mechanisms bounded by the current design basis (see Table 1) are not included in this table Note 3: Reported values are rounded to the nearest one-tenth of a foot.

Note 4: For flooding hazards within the Nuclear Plant Island Structure (NPIS), the licensee reported some flooding hazard levels in terms of ponding depth rather than water surface elevation. The NRC staff accepted the licensee's convention and present this information in terms of ponding depth, where applicable.

2

NRO/DSEA/RHM1/BC*

NAME VHall SLent LHibler CCook DATE 03/31/2016 03/31/2016 03/31/2016 03/31/2016 OFFICE NRR/JLD/JHMB/BC NRR/JLD/JHMB/PM NAME MShams VHall DATE 03/31/2016 04/12/2016

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