ML17017A318

Flood Hazard Mitigation Strategies Assessment

ML17017A318
Person / Time
Site:	Susquehanna
Issue date:	01/19/2017
From:	Tekia Govan Japan Lessons-Learned Division
To:	Franssen R Susquehanna
Govan T, NRR/JLD 415-6197
References
CAC MF6037, CAC MF6038
Download: ML17017A318 (4)

Text

UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-0001 January 19, 2017 Mr. Robert J. Franssen (Acting)

Site Vice President Susquehanna Nuclear, LLC 769 Salem Boulevard NUCSB3 Berwick, PA 18603-0467

SUBJECT:

SUSQUEHANNA STEAM ELECTRIC STATION , UNITS 1 AND 2 - FLOOD HAZARD MITIGATION STRATEGIES ASSESSMENT (CAC NOS. MF6037 AND MF6038)

Dear Mr. Franssen :

The purpose of this letter is to provide the U.S. Nuclear Regulatory Commission's (NRC's) assessment of the flood hazard mitigation strategies assessment (MSA), as described in the September 30, 2016, letter (Agencywide Documents Access and Management System (ADAMS) Accession No. ML16355A339), submitted by Susquehanna Nuclear, LLC (the licensee) for Susquehanna Steam Electric Station, Units 1 and 2 (Susquehanna). The MSA confirms that the licensee has adequately addressed the reevaluated flooding hazards within its mitigating strategies for beyond-design-basis external events.

BACKGROUND By letter dated March 12, 2012 (ADAMS Accession No. ML12053A340), the NRC issued a request for information pursuant to Title 1O of the Code of Federal Regulations (10 CFR),

Section 50.54(f) (hereafter referred to as the 50.54(f) letter) . The 50.54(f) letter 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 that licensees reevaluate flood-causing mechanisms using present-day methodologies and guidance. Concurrent with the reevaluation of flood hazards, licensees were required to develop and implement mitigating strategies using the most recent external hazard information in accordance with NRC Order EA-12-049, "Order Modifying Licenses with Regard to Requirements for Mitigation Strategies for Beyond-Design-Basis External Events" (ADAMS Accession No. ML12054A735). That order requires holders of operating reactor licenses and construction permits issued under 10 CFR Part 50 to modify the plants to provide additional capabilities and defense-in-depth for responding to beyond-design-basis external events, and to submit to the NRC for review a final integrated plan that describes how compliance with the requirements of Attachment 2 of the order was achieved. In order to proceed with implementation of Order EA-12-049, licensees used the current licensing basis flood hazard or the most recent flood hazard information, which may not be based on present-day methodologies and guidance, in the development of their mitigating strategies.

R. Franssen The NRC staff and industry recognized the difficulty in developing and implementing mitigating strategies before completing the reevaluation of flood hazards. The NRC staff described this issue and provided recommendations to the Commission on integrating these related activities in COMSECY-14-0037 , "Integration of Mitigating Strategies for Beyond-Design-Basis External Events and the Reevaluation of Flood Hazards," dated November 21 , 2014 (ADAMS Accession No. ML14309A256). The Commission issued a staff requirements memorandum on March 30, 2015 (ADAMS Accession No. ML15089A236}, affirming that the Commission expects licensees for operating nuclear power plants to address the reevaluated flood hazards, which are considered beyond-design-basis external events, within their mitigating strategies.

Nuclear Energy Institute (NEI) 12-06, Revision 2, "Diverse and Flexible Coping Strategies (FLEX) Implementation Guide" (ADAMS Accession No. ML16005A625), has been endorsed by the NRC as an appropriate methodology for licensees to perform assessments of the mitigating strategies against the reevaluated flood hazards developed in response to the March 12, 2012, 50.54(f) letter. The guidance in NEI 12-06, Revision 2, and Appendix G in particular, supports the proposed Mitigation of Beyond-Design-Basis Events rulemaking . The endorsement, including exceptions, clarifications , and additions, is described in NRC 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. ML15357A163).

Therefore , Appendix G of NEI 12-06, Revision 2, describes acceptable methods for demonstrating that the reevaluated flooding hazard is addressed within the Susquehanna mitigating strategies for beyond-design-basis external events.

MITIGATION STRATEGIES ASSESSMENT By letter dated March 5, 2015 (ADAMS Accession No. ML15063A319}, the licensee submitted its flood hazard reevaluation report for Susquehanna , as requested by Enclosure 2 of the 50.54(f) letter. By letter dated November 12, 2015 (ADAMS Accession No. ML15314A747), the NRC staff concluded , among other things , that:

1. All the reevaluated flood hazard mechanisms for Susquehanna were bounded by the current design basis of the site, and

2. It was appropriate to evaluate the mitigating strategies against the current design-basis flood hazard mechanisms.

By letter dated December 19, 2016, the licensee submitted its MSA and stated that the evaluation was performed consistent with the guidance provided in NEI 12-06, Revision 2, and that the mitigating strategies design-basis flood bounds the reevaluated flood (i. e., mitigating strategies flood hazard information) for all applicable flood-causing mechanisms, including associated effects and flood event duration parameters. Furthermore, the licensee stated that the current design basis flood protection measures implemented at the site will provide adequate protection against the reevaluated flood hazards.

The NRC staff has reviewed the flood hazard MSA for Susquehanna. The NRC staff confirmed that the licensee's flood hazard MSA was performed consistent with the guidance in Appendix G of NEI 12-06, Revision 2, as endorsed , by JLD-ISG-2012-01 , Revision 1. Based on the licensee 's inclusion of an appropriate set of equipment and its use of an appropriate hazard and

R. Franssen methodology in its MSA, the NRC staff concludes that the licensee has demonstrated that the mitigation strategies are reasonably protected from reevaluated flood hazards conditions.

If you have any questions, please contact me at (301) 415-6197 or e-mail at Tekia.Govan@nrc.gov.

Sincerely,

~0a~~

Tekia Govan, Project Manager Hazards Management Branch Japan Lessons-Learned Division Office of Nuclear Reactor Regulation Docket Nos.: 50-387 and 50-388 cc: Distribution via Listserv

ML17017A318 OFFICE NRR/JLD/JHMB/PM NRR/JLD/LA NRR/JLD/JHMB/BC NRR/JLD/JHMB/PM NAME TGovan Slent GBowrnan TGovan DATE 1/19/17 1/18/17 1/19/17 1/19/17