ML14041A336

South Texas Project, Units 1 & 2, Partial Response to Request for Additional Information Associated with Near-Term Task Force Recommendation 2.1, Flood Hazard Reevaluation (TAC Nos. MF1110 and MF1111)

ML14041A336
Person / Time
Site:	South Texas
Issue date:	01/22/2014
From:	Powell G T South Texas
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
NOC-AE-14003074, STI: 33810702, TAC MF1110, TAC MF1111
Download: ML14041A336 (6)

Text

Nuclear Operating Company South Tevas Prolect Electric Generating Station PO. Boa 28,9 Wadsworth, Temas 77483 January 22, 2014 NOC-AE-1 4003074 10 CFR 50.54(f)U.S. Nuclear Regulatory Commission Attention:

Document Control Desk Washington, DC 20555-0001 South Texas Project Units 1 & 2 Docket Nos. STN 50-498, STN 50-499 STPNOC Partial Response to Request for Additional Information Associated With Near-Term Task Force Recommendation 2.1, Flood Hazard Reevaluation (TAC Nos. MF1110 and MF1111)

References:

1. Letter from NRC to All Power Reactor Licensees, "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 the Insights from the Fukushima Dai-ichi Accident" March 12, 2012 (ML12056A046).

2. Letter from G.T. Powell, STPNOC, to NRC Document Control Desk,"Response to NRC Request for Information Pursuant to 10 CFR 50.54(f)Regarding Recommendation 2.1 Flooding of the Near-Term Task Force Review of Insights from the Fukushima Dai-ichi Accident, Enclosure 2, Required Response 2, Flood Hazard Reevaluation Report", March 11, 2013 (ML13079A806)

3. Letter from B. K. Singal, NRC, to D.L. Koehl, STPNOC, "South Texas Project, Units 1 and 2 -Request for Additional Information Regarding Fukushima Lessons Learned -Flooding Hazard Reanalysis Report ", January 14, 2014 (ML13358A065)

On March 12, 2012 (Reference 1), the U.S. Nuclear Regulatory Commission (NRC) staff issued a letter requesting additional information per Title 10 of the Code of Federal Regulations, Section 50.54(f) (hereafter called the 50.54(f) letter). The 50.54(f) letter requested that licensees reevaluate the flooding hazards at their sites against present-day regulatory guidance and methodologies.

STPNOC submitted the requested Flood Hazard Reevaluation Report to the NRC on March 11, 2013 (Reference 2)STI: 33810702 NOC-AE-14003074 Page 2 of 3 By letter dated January 14, 2014 (Reference 3), the NRC requested additional information (RAI)related to the flooding reevaluations.

Per an agreement with the NRC, STPNOC will be responding to the RAls in two parts. The first part of the STPNOC response addresses RAls 1, 2, 7, 8 and 9. The second part of the STPNOC response will address RAls 3, 4, 5 and 6 and will be submitted by February 13, 2014.The requested information for RAls 1, 2, 7, 8 and 9 is included in the attachment and enclosures submitted along with this letter There are no commitments in this letter.If there are any questions regarding.this letter, please contact Ken Taplett at (361) 972-8416 or me at (361) 972-7566.I declare under penalty of perjury that the foregoing is true and correct.Executed on .J, 2-. zd'/V G.T. Powell Site Vice President web

Attachment:

1. STPNOC Partial Response to Request for Additional Information Related to Fukushima Lessons Learned Flooding Hazard Reevaluation Report 1. Input files for RAls 1, 2, 7, 8 and 9 (DVD labeled NOC-AE-14003074 Disc 1)

Enclosures:

NOC-AE-14003074 Page 3 of 3 cc: (papercopy)(electronic copy)Regional Administrator, Region IV U. S. Nuclear Regulatory Commission 1600 East Lamar Boulevard Arlington, TX 76011-4511 Balwant K. Singal *Senior Project Manager U.S. Nuclear Regulatory Commission One White Flint North (MS 8 Bi)11555 Rockville Pike Rockville, MD 20852 NRC Resident Inspector U. S. Nuclear Regulatory Commission

• P. 0. Box 289, Mail Code: MN1 16 Wadsworth, TX 77483 Jim Collins City of Austin Electric Utility Department 721 Barton Springs Road Austin, TX 78704 A. H. Gutterman, Esquire Morgan, Lewis & Bockius LLP Balwant K. Singal U. S. Nuclear Regulatory Commission John Ragan Chris O'Hara Jim von Suskil NRG South Texas LP Kevin Polio Richard Pela L.D. Blaylock City Public Service Peter Nemeth Crain Caton & James, P.C.C. Mele City of Austin Richard A. Ratliff Robert Free Texas Department of State Health Services* Digital media enclosure is only being transmitted to the NRC Document Control Desk and to STPNOC's NRC Project Manager, Balwant K. Singal, for distribution to the NRC staff reviewers Attachment 1 NOC-AE-14003074 Page 1 of 3 STPNOC Partial Response to Request for Additional Information Related to Fukushima Lessons Learned Flooding Hazard Reevaluation Report RAI 1: Local Intense Precipitation and Associated Site Drainage Please provide electronic versions of the input files used for HEC-HMS analysis in the flood hazard reevaluation report (FHRR) related to the local intense precipitation analyses.STPNOC Response: The requested information is provided in the enclosed digital media (Disc 1).RAI 2: Local Intense Precipitation and Associated Site Drainage Please provide electronic versions of the input files used for HEC-RAS analysis in the FHRR related to local intense precipitation analyses.STPNOC Response: The requested information is provided in the enclosed digital media (Disc 1).RAI 3: Local Intense Precipitation and Associated Site Drainage Please provide descriptions of the sources of elevation data, the methods used to incorporate elevation measurements into local intense precipitation flood analysis, and the likely magnitude of the errors associated with these elevations.

STPNOC Response: The requested information will be provided by February 13, 2014 as part of the second partial RAI response.RAI 4: Local Intense Precipitation and Associated Site Drainage Please provide a description of the basis used to classify Probable Maximum Flood (PMF) flow as shallow concentrated flow used in the Natural Resources Conservation Service (NRCS) TR-55 methodology.

STPNOC Response: The requested information will be provided by February 13, 2014 as part of the second partial RAI response.

Attachment 1 NOC-AE-14003074 Page 2 of 3 RAI 5: Failure of Dams and Onsite Water Control/Storage Structures Please provide details of the ineffective flow areas and levees that were removed from the Halff Associates, Inc. HEC-RAS model while developing the HEC-RAS model used to reevaluate the flood hazard from upstream dam failures at the South Texas Project (STP), Units 1 and 2 site. Also, please provide a justification for removal of these features.STPNOC Response: The requested information will be provided by February 13, 2014 as part of the second partial RAI response.RAI 6: Failure of Dams and Onsite Water Control/Storage Structures Please provide details of the intra-basin flows that were allowed to occur in the HEC-RAS model.Also, because allowing intra-basin flows would reduce the discharge at STP, Units 1 and 2 site, the licensee is requested to provide a justification how the flood hazard from upstream dam failures would still be conservative.

STPNOC Response: The requested information will be provided by February 13, 2014 as part of the second partial RAI response.RAI 7: Failure of Dams and Onsite Water Control/Storage Structures Please provide electronic versions of the input files used for HEC-RAS analysis in the FHRR related to upstream dam failures.STPNOC Response: The requested information is provided in the enclosed digital media (Disc 1)RAI 8: Failure of Dams and Onsite Water Control/Storage Structures Please provide the electronic version of National Weather Service (NWS) BREACH model input files used in the recent Main Cooling Reservoir (MCR) breach analyses of the three postulated breach locations described in FHRR Section 2.3.STPNOC Response: The requested information is provided in the enclosed digital media (Disc 1).Note: As described in the FHRR (Reference

2) there were no BREACH model simulations performed for the Unit I and 2 flood analysis.

Rather, the output hydrograph of the BREACH model that had been developed for the Units 3 and 4 analyses was used. Also note that the same hydrograph was used for all three breach locations.

Attachment 1 NOC-AE-1 4003074 Page 3 of 3 RAI 9: Failure of Dams and Onsite Water Control/Storage Structures Please provide a description of model configuration, boundary conditions, and model parameters for the three RMA2 simulations.

Also, Please provide the RMA2 input files, including the computational grids, used for the three simulations.

STPNOC Response: The requested information is provided in the enclosed digital media (Disc 1).Note: A separate input and grid file is provided for the Unit I BREACH model, the Unit 2 BREACH model, and the Office BREACH model.