CNS-17-029, Flood Hazard Mitigating Strategies Assessment Report Submittal

Flood Hazard Mitigating Strategies Assessment Report Submittal

ML17177A099
Person / Time
Site:	Catawba
Issue date:	06/20/2017
From:	Simril T Duke Energy Carolinas
To:	Document Control Desk, Office of Nuclear Reactor Regulation
Shared Package
ML17177A098	List: CNS-17-029, Flood Hazard Mitigating Strategies Assessment Report Submittal
References
CNS-17-029
Download: ML17177A099 (5)

Text

ENERGY CNS-17-029 June 20, 2017 Attention:

Document Control Desk U.S. Nuclear Regulatory Commission Washington, D.C. 20555 Duke Energy Carolinas, LLC Catawba Nuclear Station, Units 1 and 2 Docket Nos. 50-413 and 50-414 Renewed License Nos. NPF-35 and NPF-52 Tom Simril Vice President Catawba Nuclear Station

• Duke Energy CN01VP 14800 Concord Road York, SC 29745 o: 803. 701.3340 f: 803.701.3221 tom.simril@duke-energy.com 10 CFR 50.4 10 CFR 50.54(f)

Subject:

Catawba Nuclear Station Flood Hazard Mitigating Strategies Assessment (MSA) Report Submittal

References:

1. NRC Letter, Request for Information Pursuant to Title 10 of the Code of Federal Regulations 50.54(f) Regarding Recommendations 2.1, 2.3, and 9.3, of the Near-Term Task Force Review of Insights from the Fukushima Dai-ichi Accident, dated March 12, 2012 (ADAMS Accession Number ML 12053A340).

2. Duke Energy Letter, Flood Hazard Reevaluation Report, Response to NRC 10 CFR 50.54(f) Request for Additional Information Pursuant to Title 10 of the Code of Federal Regulations 50.54(f) regarding Recommendations 2.1, 2.3 and 9.3 of the Near-Term Task Force Review of Insights from the Fukushima Dai-ichi Accident, dated March 12, 2014 (ADAMS Accession Number ML 14077A054).

3. NRC Letter, Catawba Nuclear Station, Units 1 and 2 -Interim Staff Response to Reevaluated Flood Hazards Submitted in Response to the 10 CFR 50.54(f) Information Request -Flood-Causing Mechanism Reevaluation, dated October 5, 2015 (ADAMS Accession Number ML 15278A028).

4. NRC Letter, Catawba Nuclear Station, Units 1 and 2, -Revised Interim Staff Response to Reevaluated Flood Hazards Submitted in Response to the 10 CFR 50.54(f) Information Request -Flood-Causing Mechanism Reevaluation, dated December 21, 2015 (ADAMS Accession Number ML 15352A 192). Enclosures 1 and 2 contain Security Sensitive Information; Withhold from public per 10 CFR 2.390 Upon removal of Enclosures 1 and 2, this letter is uncontrolled.

United States Nuclear Regulatory Commission Page 2 June 20, 2017 5. Duke Energy Letter, Final Notification of full Compliance with Order EA-12-049, "Order Modifying Licenses with Regard to Requirements for Mitigation Strategies for Beyond Design Basis External Events" and with Order EA-12-051, "Order to Modify Licenses with Regard to Reliable Spent Fuel Pool Instrumentation" for Catawba Nuclear Station, dated February 15, 2016 (ADAMS Accession Number ML 16049A041

). 6. Duke Energy Letter, Additional Information Regarding Flood Hazard Reevaluation Report, Response to Request for Information Pursuant to Title 10 of the Code of the Federal Regulations 50.54(f) regarding Recommendations 2.1, 2.3, and 9.3 of the Near-Term Task Force Review of Insights from the Fukushima Dai-ichi Accident, dated June 23, 2016 (ADAMS Accession Number ML 16179A196).

7. NRC Letter, Catawba Nuclear Station, Units 1 and 2 -Staff Assessment of Response to 10 CFR 50.54(f) Information Request -Flood-Causing Mechanism Reevaluation, dated September 30, 2016 (ADAMS Accession Number ML 16251A281).

8. NRC Staff Requirements Memoranda to COMSECY-14-0037, "Integration of Mitigating Strategies for Beyond-Design-Basis External Events and the Reevaluation of Flooding Hazards", dated March 30, 2015 (ADAMS Accession Number ML 15089A236).

9. Nuclear Energy Institute (NEI), Report NEI 12-06 [Rev 2], Diverse and Flexible Coping Strategies (FLEX) Implementation Guide, dated December 2015 (ADAMS Accession Number ML 16005A625).

10. U.S. Nuclear Regulatory Commission, JLD-ISG-2012-01, Revision 1, Compliance with Order EA-12-049, Order Modifying Licenses with Regard to Requirements for Mitigating Strategies for Beyond-Design-Basis External Events, dated January 22, 2016 (ADAMS Accession Number ML 15357A163).

11. United States Nuclear Regulatory Commission, NUREG/CR-7046, Design-Basis Flood Estimation for Site Characterization at Nuclear Power Plants in the United States of America, date published November 2011 (ADAMS Accession Number ML 11321A195).

On March 12, 2012, the NRC issued Reference 1 to request for information associated with Near-Term Task Force (NTTF} Recommendation 2.1 for Flooding.

Enclosure 2 to the 50.54(f) letter requested that licensees reevaluate flood hazards for their respective sites using day methods and regulatory guidance used by the NRC staff when reviewing applications for early site permits (ESPs) and combined licenses (COLs). By letter dated March 12, 2014 (Reference 2), Duke Energy provided its Flooding Hazard Reevaluation Report (FHRR) for Catawba Nuclear Station, Units 1 and 2 (CNS). Concurrent to the flood hazard reevaluation, CNS developed and implemented mitigating strategies in accordance with NRC Order EA-12-049, "Issuance of Order to Modify Licenses with Regard to Requirements for Mitigation Strategies for Beyond-Design-Basis External Events." The Final Integrated Plan provides a summary of the Mitigation Strategies (Reference 5). In Reference 8, the Commission affirmed that licensees need to address the reevaluated flooding hazards within their mitigating strategies for Beyond Design Basis external events. Guidance for performing mitigating strategies assessments (MSAs) is contained in Appendix G of Reference 9, endorsed by the NRC (with conditions) in Reference

10. Enclosures 1 and 2 contain Security Sensitive Information; Withhold from public per 10 CFR 2.390 Upon removal of Enclosures 1 and 2, this letter is uncontrolled.

United States Nuclear Regulatory Commission Page 3 June 20, 2017 On October 5, 2015 (Reference 3), the NRC issued an Interim Staff Response (ISR) letter for CNS. A revised ISR letter for CNS was issued on December 21, 2015 (Reference 4). The December 21, 2015, letter supersedes the October 5, 2015, letter. The purpose of the ISR letter was to inform CNS that the flood hazard information provided was suitable for the assessment of the mitigating strategies developed in response to Order EA-12-049, "Issuance of Order to Modify Licenses with Regard to Requirements for Mitigation Strategies for Design-Basis External Events." The reevaluated flood hazard results for Local Intense Precipitation

{LIP); streams and rivers (referred to as "Flooding in Reservoirs" in the CNS FHRR); Probable Maximum Flood (PMF); and dam failures and Combined Effects (CE) were not bounded by the current design basis flood hazard. In response to the unbounded causing mechanism, Duke Energy has completed an assessment of the mitigation strategies developed in response to Order EA-12-049 (Enclosure 1 ).

• By letter dated June 23, 2016 (Reference 6), Duke Energy advised the NRC that a refinement to the Combined Effects (CE) PMF flooding mechanism in the original CNS FHRR was in process utilizing the Hierarchal Hazard Assessment (HHA) as described in NUREG/CR-7046 (Reference 11 ). The purpose of this refined analysis was to more accurately characterize the Probable Maximum Precipitation (PMP) for the Catawba-Wateree river basin. In addition, a more appropriate method to model precipitation losses to compute runoff in conjunction with the evaluation of Combined Effects, Appendix H, of NUREG/CR-7046 (Reference

11) was performed.

A summary of this refined analysis is provided in Enclosure

2. Based on the refined analysis from the HHA process, the only flooding mechanisms that are not bounded by the Current Design Basis for CNS are the following:

1. LIP -not refined from the original FHRR, i.e. results are the same as the original FHRR 2. Dam Failures -results provided in Table 2 of Enclosure 2 from refinement through HHA process 3. Combined Effects at Lake Wylie CNS Intake -Table 2 of Enclosure 2 from refinement through HHA process In accordance with Enclosure 2 results, the Streams and Rivers (also referred to as Flooding in Reservoirs) event is now bounded by the Current Design Basis. The flooding mechanisms for Dam Failures and Combined Effects (Items 2 and 3 above) do not impact the CNS site due to the topography between the plant yard and Lake Wylie. The reevaluated LIP flood hazard results indicate that the yard inundation would impact the Auxiliary Building.

Water intrusion through Auxiliary Building doors could affect plant equipment relied upon for the FLEX strategy.

CNS will implement modifications to the FLEX strategies, so that the FLEX strategies can be* performed during the LIP event. Enclosure 1 to this letter provides the Mitigating Strategies Assessment for the CNS Flooding Report. The overall FLEX planned response to an Extended Loss of All AC Power (ELAP) and Loss of Ultimate Heat Sink (LUHS) will be initiated through normal plant command and control procedures and practices.

Site Emergency Operating Procedures (EOPs) or Abnormal Operating Procedures (AOPs) govern the operational response.

The FLEX Support Guidelines (FSGs) will provide direction for using FLEX equipment in maintaining or restoring key safety functions.

Therefore, the FLEX strategies can be deployed and implemented as modified for all applicable flood-causing mechanisms.

The FHRR. submittal (Reference

2) also provided a list of interim actions taken along with the dates these actions were implemented as regulatory commitments to address plant-specific Enclosures 1 and 2 contain Security Sensitive Information; Withhold from public per 10 CFR 2.390 Upon removal of Enclosures 1 and 2, this letter. is uncontrolled.

United States Nuclear Regulatory Commission Page4 June 20, 2017 vulnerabilities.

The intent of these actions was to enhance the current capability to maintain the plant in a safe condition during the beyond-design-basis external flooding events that exceed the current design basis flood levels while completing additional assessments and evaluations.

Duke Energy also committed not to modify any of these interim actions or completion dates without notifying the NRC in advance. By copy of this letter, Duke Energy is providing advance notification that interim actions as discussed in the FHRR Submittal will be terminated on July 20, 2017. There are no new regulatory commitments associated with this letter. Please address any comments or questions regarding this matter to Cecil A. Fletcher II, Nuclear Regulatory Affairs Manager, at (803) 701-3622.

I declare under penalty of perjury that the foregoing is true and correct. Executed on June 20, 2017. Sincerely, Tom Simril Vice President, Catawba Nuclear Station

Enclosures:

1. Mitigating Strategies Assessment for Flooding 2. Refinement to CNS FHRR Flooding in Reservoirs, Dam Failures & Combined Effects Pursuant to 10 CFR 50.54(f) Regarding the Fukushima Near-Term Task Force Recommendation 2.1 Enclosures 1 and 2 contain Security Sensitive Information; Withhold from public per 10 CFR 2.390 Upon removal of Enclosures 1 and 2, this letter is uncontrolled.

United States Nuclear Regulatory Commission Page 5 June 20, 2017 xc (with enclosures):

Catherine Haney Regional Administrator U.S. Nuclear Regulatory Commission

-Region II Marquis One Tower 245 Peachtree Center Ave., NE Suite 1200 Atlanta, GA 30303-1257 Juan F. Uribe U.S. Nuclear Regulatory Commission One White Flint North, Mailstop 0-13F10 11555 Rockville Pike Rockville, MD 20852-2738 Michael Mahoney NRC Project Manager (CNS) U.S. Nuclear Regulatory Commission One White Flint North, Mail Stop 0-8H4A 11555 Rockville Pike Rockville, MD 20852-2738 Joseph D. Austin NRC Senior Resident Inspector Catawba Nuclear Station xc (without enclosures):

Justin Folkwein American Nuclear Insurers 95 Glastonbury Blvd., Suite 300 Glastonbury, CT 06033-4453 Enclosures 1 and 2 contain Security Sensitive Information; Withhold from public per 10 CFR 2.390 Upon removal of Enclosures 1 and 2, this letter is uncontrolled.