ML17072A364
| ML17072A364 | |
| Person / Time | |
|---|---|
| Site: | Brunswick  |
| Issue date: | 03/16/2017 |
| From: | Juan Uribe Japan Lessons-Learned Division |
| To: | William Gideon Progress Energy Carolinas |
| Uribe J, NRR/JLD, 415-3089 | |
| Shared Package | |
| ML17072A350 | List: |
| References | |
| CAC MF6104, CAC MF6105 | |
| Download: ML17072A364 (8) | |
Text
OFFICIAL USE ONLY - SECURITY RELATED INFORMATION UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-0001 Mr. William R. Gideon Site Vice President Brunswick Steam Electric Plant 8470 River Rd. SE (M/C BNP001)
Southport, NC 28461 March 16, 2017
SUBJECT:
BRUNSWICK STEAM ELECTRIC PLANT, 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 (CAC NOS. MF6104 AND MF6105)
Dear Mr. Gideon:
The purpose of this letter is to provide a summary of the U.S. Nuclear Regulatory Commission (NRG) staff's assessment of the reevaluated flood-causing mechanisms described in the March 11, 2015, flood hazard reevaluation report (FHRR) submitted by Duke Energy Progress, LLC (Duke, the licensee) for Brunswick Steam Electric Plant, Units 1 and 2 (Brunswick)
(Agencywide Documents Access and Management System (ADAMS) Accession No. ML15079A385), as well as supplemental information resulting from audits.
By letter dated March 12, 2012, the NRG issued a request for information pursuant to Title 1 O 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 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 NRG 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.
Revision 2 of Nuclear Energy Institute (NEI) guidance document NEI 12-06, dated December 2015, includes a methodology for performing a mitigating strategies assessment (MSA) with respect to the reevaluated flood hazards. 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 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). Based on the guidance provided in Revision 2 of NEI 12-06, any flood event duration parameters and applicable flood associated effects that were not provided in the FHRR should be considered as part of the Brunswick 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.
In addition to the MSA, in order to complete its response to the information requested by to the 50.54(f) letter, the licensee is expected to submit an integrated assessment or a focused evaluation, as appropriate, to address the reevaluated flood hazards that exceed the current design basis, 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).
The NRC staff has reviewed the information submitted by the licensee in its FHRR and the associated regulatory audit (ADAMS Accession No. ML15148A762), 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 performed a confirmatory analysis of the information provided in the FHRR to independently evaluate the sensitivity of the reevaluated hazards to input parameters. The confirmatory analysis indicated that the storm surge flood-causing mechanism is sensitive to the input parameters and methodology used. The sensitivities identified have been discussed with the licensee. As a measure of conservatism, the licensee agreed to provide margin above the FHRR stillwater elevations for storm surge for the subsequent flood evaluations addressing flooding due to storm surge. The water elevations summarized in Table 2 reflect this commitment.
Based on the information provided by the licensee and the staff's confirmatory analysis, the NRC staff has concluded that the reevaluated flood hazard information, as summarized in Table 2 of 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 NEI guidance document NEI 12 06, "Diverse and Flexible Coping Strategies (FLEX)
Implementation Guide") for Brunswick. Further, the NRC staff has concluded that the enclosed reevaluated flood hazard information is suitable input for other flooding assessments associated with the 50.54(f) letter. The NRC staff plans to issue a staff assessment documenting the basis for these conclusions at a later time.
OFFICIAL USE ONLY-SECURITY RELATED INFORMATION
OFFICIAL USE ONLY - SECURITY RELATED INFORMATION If you have any questions, please contact me at (301) 415-3809 or e-mail at Juan.Uribe@nrc.gov.
Docket Nos. 50-325 and 50-324
Enclosures:
- 1. Summary of Results of Flooding Sin
- rely, I
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Jua ribe, Project Manager Hazards Management Branch Japan Lessons-Learned Division Office of Nuclear Reactor Regulation 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
Brunswick Steam Electric Plant, Units 1 & 2 Table 1. Current Design Basis Flood Hazards for Use in the MSA Mechanism I
Stillwater Waves/
Design Basis Reference Elevation Run up Hazard Elevation Local Intense Precipitation Not included Not included Not included FHRR Section 3b.1 and Table 5-1 in DB in DB in DB Streams and Rivers Not included Not included Not included FHRR Section 3b.2 & Table 5-1 in DB in DB in DB Failure of Dams and Onsite I
Water Control/Storage Structures Not included Not included Not included FHRR Section 3b.3 and Table 5-1 in DB in DB in DB Storm Surge At Site Safety Related Buildings 22.0 ft 3.6ft 25.6 ft FHRR Section 3b.4 and Table 5-1 NGVD29 NGVD29 FHRR Section 3b.7 and Table 5-1 At Site Safety Related Buildings Not Not 26.1 ft FHRR Section 3b.7 with Margin Added applicable applicable NGVD29 At Intake Structure 25.3 ft 3.0ft 28.3 ft FHRR Section 3b.7 NGVD29 NGVD29
~
Seiche Not included Not included Not included FHRR Section 3b.4 and Table 5-1 in DB in DB in DB I Tsunami Not included Not included Not included FHRR Section 3b.5 and Table 5-1 in DB in DB in DB I
Brunswick Steam Electric Plant, Units 1 & 2 Table 1. Current Design Basis Flood Hazards for Use in the MSA Mechanism Stillwater Waves/
Design Basis Reference Elevation Run up Hazard Elevation Ice-Induced Flooding Not included Not included Not included FHRR Section 3b.6 and Table 5-1 in DB in DB in DB Channel Migrations/Diversions Not included Not included Not included FHRR Table 5-1 in DB in DB in DB Note 1: Reported values are rounded to the nearest one-tenth of a foot.
Note 2: Storm Surge Flood-Causing Mechanism includes a combined analysis of both surge and seiche.
Brunswick Steam Electric Plant, 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 Elevation Local Intense Precipitation Reactor Building (Door D-3) 21.1 ft Minimal 21.1 ft FHRR Section 4a and Tables 4-2 & 5-NGVD29 NGVD29 1
Turbine Building (Door D-24) 21.7 ft Minimal 21.7ft FHRR Tables 4-3 & 5-1 NGVD29 NGVD29 Reactor Building (Door D-2) 20.8 ft Minimal 20.8 ft FHRR Section 4a and Tables 4-2 & 5-NGVD29 NGVD29 1
c-Streams and Rivers Cape Fear River 11.9 ft 4.4 ft 16.3 ft FHRR Section 4b & Table 5-1 NGVD29 NGVD29 FHRR Section 4b, Table 4-18, &
Table 5-1 Nancy's Creek I
15.5 ft Minimal 15.5 ft FHRR Section 4b & Table 5-1 NGVD29 NGVD29 Failure of Dams and Onsite Water Control/Storage Structures REDACTED REDACTED REDACTED REDACTED REDACTED REDACTED REDACTED REDACTED REDACTED REDACTED Storm Surge Reactor Building 26.5 ft 7.0 ft 33.5 ft See Note 5 NGVD29 NGVD29 Diesel Generator Building 26.5 ft 7.1 ft 33.6 ft See Note 5 NGVD29 NGVD29
Brunswick Steam Electric Plant, Units i &.2 Table 2. Reevaluated Flood Hazards for Flood-Causing Mechanisms for Use in the MSA Mechanism Stillwater Waves/
Reevaluated Reference Elevation Run up Hazard Elevation
~
Service Water Building/Intake 26.4 ft 7.1 ft 33.5 ft See Note 5 Structure NGVD29 NGVD29 AOG Building 26.4 ft 7.2 ft 33.6 ft See Note 5 NGVD29 NGVD29 Radwaste Building 26.5 ft 7.2 ft 33.7 ft See Note 5 NGVD29 NGVD29 Turbine Building 26.7 ft 7.1 ft 33.8 ft See Note 5 NGVD29 NGVD29 Tsunami At the Intake Canal 10.2 ft Not 10.2 ft FHRR Section 4E & Table 5-1 NGVD29 applicable NGVD29 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: Wind/Wave effects for streams and rivers flood-causing mechanism were determined using combined effects PMH based wind/wave effects noted in Rev. 0 of the FHRR.
Note 5: For the storm surge hazard, the elevations presented in this table include adjustments (relative to results presented in the FHRR) to account for (1) sensitivity and uncertainty associated with the wind drag functions used in numerical storm surge models and (2) the calculation of the tidal component of the antecedent water level.
Note 6: Storm Surge Flood-Causing Mechanism includes a combined analysis of both surge and seiche.
I
OFFICIAL USE ONLY-SECURITY RELATED INFORMATION BRUNSWICK STEAM ELECTRIC PLANT, UNITS 1AND2-INTERIM STAFF RESPONSE TO REEVALUATED FLOOD HAZARDS SUBMITTED IN RESPONSE TO 10 CFR 50.54(f)
INFORMATION REQUEST-FLOOD-CAUSING MECHANISM REEVALUATION DATED MARCH 16, 2017 DISTRIBUTION:
PUBLIC JUribe, NRR RidsNrrDorllpl2 Resource RidsRgn2MailCenter Resource RidsOpaMail Resource ACampbell, NRO MWillingham, NRO MShams, NRR JLD R/F LQuinn-Willingham, NRO RidsNrrDorl Resource RidsNrrLASLent RidsAcrsAcnw_MailCtr Resource RRivera-Lugo, NRO KSee, NRO RidsNRRJLD Resource RidsNroDsea Resource RidsNrrPMBrunswick Resource RidsOgcMailCenter Resource CCook, NRO LGibson, NRR BHarvey, NRO ADAMS Accession Nos.: Pkg; ML17072A350; Non-Public Letter: ML17072A355; Public Letter: ML17072A364; Enclosure 1: ML17072A420; Enclosure 2: ML17072A452
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