ML16035A265
| ML16035A265 | |
| Person / Time | |
|---|---|
| Site: | Oyster Creek |
| Issue date: | 02/09/2016 |
| From: | Tekia Govan Japan Lessons-Learned Division |
| To: | Bryan Hanson Exelon Nuclear |
| Govan, Tekia NRR/JLD 415-6197 | |
| References | |
| CAC MF6111 | |
| Download: ML16035A265 (7) | |
Text
Mr. Bryan C. Hanson President and Chief Nuclear Officer Exelon Nuclear 4300 Winfield Road Warrenville, IL 60555 UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-0001 February 9, 2016
SUBJECT:
OYSTER CREEK NUCLEAR GENERATING STATION-INTERIM STAFF RESPONSE TO REEVALUATED FLOOD HAZARDS SUBMITTED IN RESPONSE TO 10 CFR 50.54(f) INFORMATION REQUEST - FLOOD-CAUSING MECHANISM REEVALUATION (CAC NO. MF6111)
Dear Mr. Hanson:
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 March 12, 2015 (Agencywide Documents Access and Management System (ADAMS)
Accession No. ML15085A046), flood hazard reevaluation report (FHRR) submitted by Exelon Generation Company, LLC (the licensee) for Oyster Creek Nuclear Generating Station (Oyster Creek), 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 reevaluate 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 reevaluated flood hazard mechanisms; however, reevaluated 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 Oyster Creek. 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 January 22, 2016, the NRC staff approved and made publicly available Japan Lessons-Learned Division 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), with publication in the Federal Register to follow. 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 Oyster Creek 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) 415-6197 or e-mail at Tekia.Govan@nrc.gov.
Docket No. 50-219
Enclosure:
Summary of Results of Flooding Hazard Re-Evaluation Report cc w/encl: Distribution via Listserv Sincerely,
~~~
Tekia Govan, Project Manager Hazards Management Branch Japan Lessons-Learned Division Office of Nuclear Reactor Regulation
ENCLOSURE:
SUMMARY
TABLES OF REEVALUATED FLOOD HAZARD LEVELS
Oyster Creek Table 1. Current Design Basis Flood Hazards for Use in the MSA Mechanism Local Intense Precipitation Streams and Rivers Failure of Dams and Onsite Water Control/Storage Structures Storm Surge Storm Surge Seiche Tsunami Ice-Induced Flooding Channel Migrations/Diversions I
I Stillwater Elevation 1
23.5 ft msl 1
I I
I No Impact on the Site Identified No Impact on the Site Identified 22.0 ft msl I
I i
i Waves/
Run up Minimal No Impact on the Site Identified No Impact on the Site Identified 1.0 ft Not included
'* Not included in DB i
in DB I
I
! Not included Not included in DB in DB I
No Impact on the Site Identified Not included in DB No Impact on the Site Identified Not included in DB Design Basis Hazard Elevation i
23.5 ft msl 1
I No Impact on the Site Identified No Impact on the Site Identified 23.0 ft msl Not included in DB Not included in DB I
No Impact on the Site 1
Identified I
Not included 1
in DB 1
I I
Note 1: Reported values are rounded to the nearest one-tenth of a foot.
Reference FHRR Enclosure 2 Section 2.2 FHRR Enclosure 2 Section 2.2 FHRR Enclosure 2 Section 2.2 FHRR Enclosure 2 Section 2.2 FHRR Enclosure 2 Section 2.2 FHRR Enclosure 2 Section 2.2 FHRR Enclosure 2 Section 2.2 FHRR Enclosure 2 Section 2.2
Oyster Creek Table 2. Reevaluated Flood Hazards for Flood-Causing Mechanisms for Use in the MSA Mechanism Local Intense Precipitation Stillwater Elevation I
Waves/
1 Reevaluated Runup i
Hazard Elevation Max Water Surface Elevation at 1
24.4 ft msl 1
Minimal 24.4 ft msl Door#9
--- i---
Storm Surge Site Emergency Building -
Combined Effects Flood Turbine Building - Combined Effects Flood Intake Structure 1
22.9 ft msl 23.2 ft msl 23.2 ft msl I
3.7 ft 26.6 ft msl 1
2.7 ft 25.9 ft msl 1.4 ft 24.6 ft msl Reference Correspondence Dated 1 /14/16 (ML16015A001)
FHRR Enclosure 2 Table 2 FHRR Enclosure 2 Table 2 FHRR Enclosure 2 Table 2 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.
PKG: ML16035A266; LTR: ML16035A265; ENCL: ML16034A132
- via email OFFICE NRR/JLD/JHMB/PM NRR/JLD/LA NRO/DSEA/RHM2/TR*
NRO/DSEA/RHM2/BC*
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