ML15230A070

Interim Staff Response to Reevaluated Flood Hazards Submitted in Response to 10CFR50.54 Information Request - Flood Causing Mechanism Reevaluation

ML15230A070
Person / Time
Site:	Mcguire, McGuire
Issue date:	09/03/2015
From:	Juan Uribe Japan Lessons-Learned Division
To:	Capps S Duke Energy Carolinas
Uribe, Juan NRR/JLD 415-3809
Shared Package
ML15230A161	List: ML15226A525 ML15230A070
References
TAC MF3623, TAC MF3624
Download: ML15230A070 (8)

Text

UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-0001 September 3, 2015 Mr. Steven D. Capps Vice President - McGuire Site Duke Energy Carolinas, LLC McGuire Nuclear Station 12700 Hagers Ferry Road Huntersville, NC 28078-8985

SUBJECT:

MCGUIRE NUCLEAR STATION, UNITS 1 AND 2 - INTERIM STAFF RESPONSE TO REEVALUATED FLOOD HAZARDS SUBMITTED IN RESPONSE TO 10 CFR 50.54(f) INFORMATION REQUEST- FLOOD-CAUSING MECHANISM REEVALUATION (TAC NOS. MF3623 AND MF3624)

Dear Mr. Capps:

The purpose of this letter is to provide a summary of the U.S. Nuclear Regulatory Commission (NRC) staff's assessment of the re-evaluated flood-causing mechanisms described in the March 12, 2014 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML14083A415), flood hazard reevaluation report (FHRR) submitted by Duke Energy Carolinas, LLC (Duke, the licensee) for the McGuire Nuclear Station, Units 1 and 2 (McGuire), 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 this information 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;

S. Capps 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 guidance documents currently being finalized by the industry and NRC staff), for McGuire. 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.

In addition, NEI 12-06 "Diverse and Flexible Coping Strategies (FLEX) Implementation Guide" is currently being revised. This revision will include a methodology to perform a Mitigating Strategies Assessment (MSA) with respect to the reevaluated flood hazards. Once this methodology is endorsed by the NRC, flood event duration parameters and applicable flood associated effects should be considered as part of the McGuire 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).

S. Capps If you have any questions, please contact me at (301) 415-3809 or e-mail at Juan.Uribe@nrc.gov.

Sincerely, 1 J:1 Uribe, Project Manager ._

Hazards Management Branch Japan Lessons-Learned Division Office of Nuclear Reactor Regulation Docket Nos. 50-369 and 50-370

Enclosure:

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

ENCLOSURE:

SUMMARY

TABLES OF REEVALUATED FLOOD HAZARD LEVELS

McGuire, Units 1 & 2 Table 1. Current Design Basis Flood Hazards for Use in the MSA Mechanism Stillwater Waves/ Design Basis Reference I Elevation Run up Hazard I

- --- - - - -- ~ ----

Elevation Local Intense Precipitation 760.4 ft msl 0.0 ft 760.4 ft msl FHRR Section 1.2.1 Streams and Rivers Reservoir Level at Cowans 767.9 ft msl 5.1 ft 773.0 ft msl FHRR Section 1.2.2 I

Ford Dam FHRR Section 1.2.8 (Table 1.2.8-1)

Failure of Dams and Onsite Water Control/Storage Structures Upstream Dam Failures 762.6 ft msl 5.1 ft I 767.7 ft msl FHRR Section 1.2.3 (combined event) FHRR Section 1.2.3 (Table 1.2.8-1)

I i

Standby Nuclear Service Water 746.9 ft msl 1.5 ft 748.4 ft msl FHRR Table 3-1 Pond (combined event)

Standby Nuclear Service Water 727.8 ft msl Not 727.8 ft msl FHRR Table 3-1 Pond Dam Downstream applicable (combined event)

Storm Surge Surge in Lake Norman 760.0 ft msl 14.8 ft 774.8 ft msl FHRR Section 1.2.4 Seiche No Impact No Impact No Impact FHRR Section 1.2.4 on the Site on the Site on the Site Identified Identified Identified Tsunami Not included Not included Not included FHRR Section 1.2 in DB in DB in DB I

-- - - - - -- ____j_ ----------- ---- _____L

McGuire, Units 1 & 2 Table 1. Current Design Basis Flood Hazards for Use in the MSA I Mechanism Stillwater Waves/ Design Basis Reference I

I Elevation Run up Hazard I i Elevation I Ice-Induced Flooding i

I Not included Not included Not included FHRR Section 1.2 in DB in DB in DB I I I I Channel Migrations/Diversions Not included Not included Not included FHRR Section 1.2 in DB in DB in DB Note 1: Reported values are rounded to the nearest one-tenth of a foot.

Note 2: The wave hieght value of 5.1 ft for the Streams and Rivers, and Upstream Dam Failures (combined event) is wave setup plus runup.

McGuire, Units 1 & 2 Table 2. Reevaluated Flood Hazards for Flood-Causing Mechanisms for Use in the MSA 1- - --

Mechanism Stillwater Waves/ Reevaluated Reference Elevation Run up Hazard Elevation Local Intense Precipitation 761.1ftmsl Minimal 761.1ftmsl FHRR Section 2.1 I

I Strea~s and Rivers ___ --+---- . , ,.

I River PMF in Lake Norman 777.9 ft msl Not 777.9 ft msl FHRR Section 2.2 and 2.8 applicable I

Failure of Dams and Onsite Water Control/Storage Structures Upstream Dam Failures 778.5 ft msl Not 778.5 ft msl FHRR Section 2.3 and 2.8 (combined event) applicable Standby Nuclear Service Water 735.9 ft msl 0.9 ft 736.8 ft msl FHRR Tables 2.4.2-1 and 2.4.2-2 Pond Dam Downstream (combined event)

Storm Surge 778.5 ft msl 0.0 ft 778.5 ft msl FHRR Table 3-1 FHRR Section 2.4.1(Table2.4.1-1)

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 6f a foot.

PKG ML15230A161, LTR: ML15230A070, ENCL: ML15226A525 *via email OFFICE NRR/JLD/JHMB/PM NRR/JLD/LA NRO/DSEA/RHM2ffR*

NAME JUribe Slent HAhn DATE 8/18/2015 8/18/2015 8 / 17 /15 OFFICE NRR/JLD/JHMB/BC NRO/DSEA/RHM2/BC* NRR/JLD/JHMB/PM NAME MShams ARivera-Varona JUribe DATE 8 / 28 /15 8 / 17 /15 9 / 3 /15