ML15352A192
| ML15352A192 | |
| Person / Time | |
|---|---|
| Site: | Catawba  |
| Issue date: | 12/21/2015 |
| From: | Juan Uribe Japan Lessons-Learned Division |
| To: | Henderson K Duke Energy Carolinas |
| Uribe, Juan NRR/JLD 415-3809 | |
| References | |
| TAC MF3625, TAC MF3626 | |
| Download: ML15352A192 (8) | |
Text
UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-0001 Mr. Kelvin Henderson Site Vice President Duke Energy Carolinas, LLC Catawba Nuclear Station 4800 Concord Road York, SC 297 45 December 21, 2015
SUBJECT:
CATAWBA NUCLEAR STATION, UNITS 1AND2-REVISED INTERIM STAFF RESPONSE TO REEVALUATED FLOOD HAZARDS SUBMITTED IN RESPONSE TO 10 CFR 50.54(f) INFORMATION REQUEST-FLOOD-CAUSING MECHANISM REEVALUATION (TAC NOS. MF3625 AND MF3626)
Dear Mr. Henderson:
By letter dated October 5, 2015 (Agencywide Documents Access and Management System (ADAMS) Accession No.ML15278A017) the U.S. Nuclear Regulatory Commission (NRC) transmitted to you the Interim Staff Response to the reevaluated flood hazards for Catawba Nuclear Station, Units 1 and 2 (Catawba). In that letter, Table 1 contained the current design-basis (COB) values against which the reevaluated flooding hazard mechanisms were compared in order to determine whether or not the reevaluated values were bounded. Upon further review, the NRC staff identified an error in Table 1 in the form of incorrect COB values for local intense precipitation (LIP) for both Unit 1 and Unit 2, which consequently impacted the reevaluated flood hazard results documented in Table 2. This letter updates the COB LIP values in Table 1 and the flood hazard mechanisms in Table 2 that should be considered in the mitigating strategies assessment (MSA) and subsequent Near-Term Task Force (NTTF)
Recommendation 2.1: Flooding activities, as described below. This letter supersedes the October 5, 2015, letter.
This letter provides a summary of the NRC staff's assessment of the re-evaluated flood-causing mechanisms described in the March 12, 2014 (ADAMS Accession No. ML14077A054), flood hazard reevaluation report submitted by Duke Energy Carolinas, LLC (Duke Energy, the licensee) for Catawba, as well as supplemental information resulting from requests for additional information {RAI) 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. 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 COB flood hazard mechanisms. Table 2 provides the reevaluated flood hazard mechanisms; however, the reevaluated flood hazard mechanisms bounded by the COB (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 Catawba. Further, the NRC staff has concluded that the licensee's reevaluated flood hazard information is a suitable input for other assessments associated with NTTF 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, the Nuclear Energy Institute (NEI) guidance document NEI 12-06 "Diverse and Flexible Coping Strategies (FLEX) Implementation Guide" is currently being revised. This revision will include a methodology to perform a 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 Catawba 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 COB. 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 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) 415-3809 or e-mail at ju an. uribe@nrc.gov.
Docket Nos. 50-413 and 50-414
Enclosure:
Summary of Results of Flooding Hazard Re-Evaluation Report cc w/encl: Distribution via Listserv Jua ribe, Pro ct Manager Hazards Management Branch Japan Lessons-Learned Division Office of Nuclear Reactor Regulation
ENCLOSURE:
SUMMARY
TABLES OF REEVALUATED FLOOD HAZARD LEVELS
Catawba, Units 1 & 2 Table 1. Current Design Basis Flood Hazards for Use in the MSA Mechanism Local Intense Precipitation Unit 1 Side of the Yard Unit 2 Side of the Yard Streams and Rivers Lake Wylie CNS Intake Standby Nuclear Service Water Pond Dam Failure of Dams and Onsite Water Control/Storage Structures Lake Wylie CNS Intake (Combined Effects)
Standby Nuclear Service Water Pond (Combined Effects)
Allison Creek CNS Discharge (Combined Effects)
Storm Surge Lake Wylie Storm Surge and Seiche i
stmwaier -
- waves/--*--o-esign sasis -
- -Rete-.:e-nce-
- - * * * *1 Elevation Run up Hazard 594.9 ft msl 595.9 ft msl 581.1ftmsl 583.5 ft msl 592.4 ft msl 592.4 ft msl 592.4 ft msl 569.4 ft msl Minimal Minimal Not applicable 1.0 ft 1.5 ft 2.2 ft 1.2 ft 8.4 ft Elevation 594.9 ft msl Response to NRC Request for Additional Information Regarding the FHRR, dated July 28, 2015 (ADAMS Accession No. ML15222A535) 595.9 ft msl Response to NRG Request for 581.1 ft msl 584.5 ft msl 593.9 ft msl 594.6 ft msl 593.6 ft msl 577.8 ft msl Additional Information Regarding the FHRR, dated July 28, 2015 (ADAMS Accession No. ML15222A535)
FHRR Section 1.2.2 and Table 3-1 FHRR Section 1.2.2 FHRR Table 1.2.8-1 FHRR Table 1.2.8-1 FHRR Table 1.2.8-1 FHRR Section 1.2.4
Catawba, 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 i
Elevation Seiche No Impact No Impact No Impact FHRR Section 1.2 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 Ice-Induced Flooding No Impact No Impact No Impact FHRR Section 1.2 on the Site on the Site on the Site Identified Identified Identified i
Channel Migrations/Diversions i No Impact No Impact No Impact FHRR Section 1.2 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.
Catawba, Units 1 & 2 Table 2. Reevaluated Flood Hazards for Flood-Causing Mechanisms for Use in the MSA Mechanism I
Stillwater Waves/
! Reevaluated Reference Elevation Run up Hazard Elevation Local Intense Precipitation Unit 1 Side of the Yard 595.5 ft rnsl Minimal 595.5 ft rnsl FHRR Section 2.1 and Table 3-1 Streams and Rivers i
Lake Wylie CNS Intake 590.7 ft rnsl Not 590.7 ft rnsl FHRR Section 2.2.2 applicable Standby Nuclear Service Water 583.0 ft rnsl 0.8 ft 583.8 ft msl FHRR Section 2.4.1 and Table 2.4.3-Pond Dam (LIP) 1 Failure of Dams and Onsite i
Water Control/Storage Structures Lake Wylie CNS Intake 602.2 ft msl 1.0 ft 603.2 ft msl FHRR Section 2.8.1, Table 3-1, and (Combined Effects)
Table 2.8.1-1 Standby Nuclear Service Water 602.2 ft msl 1.0 ft 603.2 ft msl FHRR Table 2.4.2-1 and Table 3-1 Pond (Combined Effects)
FHRR Table 2.8.1-1 Allison Creek CNS Discharge 599.8 ft msl Not 599.8 ft msl FHRR Table 2.3.2-4 and Table 3-1 (Combined Effects) applicable 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.
If you have any questions, please contact me at (301) 415-3809 or e-mail at juan.uribe@nrc.gov.
Sincerely, IRA!
Juan Uribe, Project Manager Hazards Management Branch Japan Lessons-Learned Division Office of Nuclear Reactor Regulation Docket Nos. 50-413 and 50-414
Enclosure:
Summary of Results of Flooding Hazard Re-Evaluation Report cc w/encl: Distribution via Listserv DISTRIBUTION:
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