ML14029A533

South Texas Project Units 1 and 2 - Response to Request for Additional Information Re Use of RELAP5 in Analyses for Risk-Informed GSI-191 Licensing Application

ML14029A533
Person / Time
Site:	South Texas
Issue date:	01/09/2014
From:	Powell G T South Texas
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
NOC-AE-13003057, TAC MF2400, TAC MF2401, TAC MF2402, TAC MF2403, TAC MF2404, TAC MF2405, TAC MF2406, TAC MF2407, TAC MF2408, TAC MF2409
Download: ML14029A533 (10)

Text

Contents of enclosed digital media should be withheld from public disclosurein accordance withl0CFR2.390Nuclear Operating CompanySouth Texas Project Electric Generating Station PO. Say 289 Wadsworth. Tetas 77483 /January 9, 2014NOC-AE-13003057D43.0210 CFR 2.390Attention: Document Control DeskU. S. Nuclear Regulatory CommissionWashington, DC 20555-0001South Texas ProjectUnits 1 and 2Docket Nos. STN 50-498 and 50-499Response to Request for Additional Information re Use of RELAP5 inAnalyses for Risk-Informed GSI-191 Licensing Application(TAC NOS. MF2400, MF2401, MF2402, MF2403,MF2404, MF2405, MF2406, MF2407, MF2408, AND MF2409)Reference: E-mail, Balwant Singal, NRC, to Albon Harrison, STP, "Request forAdditional Information -TACs MF2400 through and MF2409",January 9, 2014 (ML14009A307)By the reference above, the NRC requested the RELAP5 code and modeling used for thethermal-hydraulic analyses in the STP Nuclear Operating Company (STPNOC) licensingapplication for a risk-informed approach to the resolution of Generic Safety Issue (GSI)-191. The requested RELAP5 information is provided in the enclosed digital media.The information and analyses embodied in the code are considered to be proprietary andare accompanied by a formal request to withhold the documents from public disclosure inaccordance with IOCFR2.390 (Attachment 1). The content of the enclosed digital mediais considered to be proprietary in its entirety, so no redacted non-proprietary version isprovided.There are no regulatory commitments in this submittal.STI: 33793079 NOC-AE-13003057Page 2 of 3If there are any questions regarding this request, 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: 9 _ oG. T. PowellSite Vice PresidentawhAttachments:Enclosure:1. Affidavit and Application for Withholding Proprietary Informationfrom Public Disclosure2. Response to NRC Request for Additional InformationRELAP5 digital media(Ten (10) DVDs labeled NOC-AE-13003057 Disc 1 -10)

NOC-AE-13003057Page 3 of 3cc:(paper copy)(electronic copy)Regional Administrator, Region IVU. S. Nuclear Regulatory Commission1600 East Lamar BoulevardArlington, TX 76011-4511Balwant K. SingalSenior Project ManagerU.S. Nuclear Regulatory CommissionOne White Flint North (MS 8 B 1)11555 Rockville PikeRockville, MD 20852NRC Resident InspectorU. S. Nuclear Regulatory CommissionP. 0. Box 289, Mail Code: MN1 16Wadsworth, TX 77483Jim CollinsCity of AustinElectric Utility Department721 Barton Springs RoadAustin, TX 78704A. H. Guttennan, EsquireMorgan, Lewis & Bockius LLPBalwant K. SingalMichael MarkleyJohn StangU. S. Nuclear Regulatory CommissionJohn RaganChris O'HaraJim von SuskilNRG South Texas LPKevin PolloRichard PenaL.D. BlaylockCity Public ServicePeter NemethCrain Caton & James, P.C.C. MeleCity of AustinRichard A. RatliffTexas Department of State Health ServicesRobert FreeTexas Department of State Health Services

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1 NOC-AE-13003057Page 1 of 3UNITED STATES OF AMERICANUCLEAR REGULATORY COMMISSIONIn the Matter of ))STP Nuclear Operating Company ) Docket Nos. 50-498)50-499South Texas Project )Units I and2 )AFFIRMATIONI, G. T. Powell, being duly sworn, hereby depose and state that I am Site Vice President of STPNuclear Operating Company (STPNOC); that I am duly authorized to sign and file with theNuclear Regulatory Commission the attached application for withholding proprietaryinformation from public disclosure, that I am familiar with the content thereof; and that thematters set forth therein are true and correct to the best of my knowledge and belief.G. T. PowellSite Vice PresidentSTPNOCSTATE OF TEXAS ))COUNTY OF MATAGORDA )Subscribed and sworn to before me, a Notary Public in and for the State of Texas,this day of 2013.AR.E.'% otary Puic in and for the/State of Texas

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I NOC-AE-13003057Page 2 of 3In accordance with 10 CFR 2.390(b)(ii):(A) The specific information for which withholding from public disclosure is sought isthe RELAP5 model of the STP Units 1 and 2 Nuclear Steam Supply System (NSSS)and input data that describes how the NSSS model will be specifically applied to theanalyses used in the STPNOC risk-informed GSI-191 pilot project.(B) The official position of the person making this affidavit is the Site Vice President ofSTPNOC, who has been specifically delegated the function of reviewing the informationsought to be withheld and authorized to apply for its withholding on behalf of STPNOC.(C) The basis for proposing the information be withheld is that the information constitutestrade secrets and commercial or financial information obtained from a person andprivileged or confidential [1OCFR2.390(a)(4)].(D) The harm that would result if the information sought to be withheld is disclosed to thepublic is described below.(E) The entire code and associated input specified in part (A) are considered to beproprietary. Therefore, there are no individual locations in the information marked"proprietary."In accordance with 10 CFR 2.390(b)(iii), the following is a full statement of the reason forclaiming the information should be withheld from public disclosure.This model and associated data are a first-of-a-kind activity, which would havecommercial benefit for other contractors/vendors if it were disclosed to thepublic. The input data also contains information that is proprietary toWestinghouse that is not contained in publicly available Westinghouse literature.Finally, the model and data draw application conclusions that are unique to theSouth Texas Project, which could be potentially misused by others if thedocument were disclosed to the public.Further, STPNOC affirms that:(i) The information has been held in confidence by STPNOC.(ii) The information is of a type customarily held in confidence by STPNOC and there is arational basis for doing so.(iii) The information has been transmitted to the NRC in confidence.(iv) The information is not available in public sources.

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1 NOC-AE- 13003057Page 3 of 3(v) Public disclosure of the information sought to be withheld is likely to causesubstantial harm to the competitive position of STPNOC, taking into account: thevalue of the information to STPNOC; the amount of money and effort expended bySTPNOC in developing the information; and the ease or difficulty with which theinformation could be properly acquired or duplicated by others.

Attaclunent 2NOC-AE- 13003057Response to NRC Request for Additional InformationREQUEST FOR ADDITIONAL INFORMATIONLICENSE AMENDMENT REQUESTRISK-INFORMED APPROACH TO RESOLVING GSI- 191SOUTH TEXAS PROJECT, UNITS 1 AND 2DOCKET NOS. 50-498, 50-499By letter dated June 19, 2013 (Agencywide Documents Access and Management System(ADAMS) Accession Number ML131750250), STP Nuclear Operating Company (STPNOC, thelicensee) for South Texas Project (STP), Units 1 and 2, submitted a request for exemptions andlicense amendment request (LAR) for a risk-informed approach to resolving generic safety issue(GSI)-191.Title 10 of the Code qf Federal Regulations (CFR) Section 50.46(a)(1)(i) states, in part:ECCS [Emergency Core Cooling System] cooling performance must be calculated inaccordance with an acceptable evaluation model and must be calculated for a number ofpostulated loss-of-coolant accidents of different sizes, locations, and other propertiessufficient to provide assurance that the most severe postulated loss-of-coolant accidentsare calculated. Except as provided in paragraph (a)(1)(ii) of this section, the evaluationmodel must include sufficient supporting justification to show that the analyticaltechnique realistically describes the behavior of the reactor system during a loss-of-coolant accident.The ECCS evaluation model must also meet the specific requirements of 10 CFR 50.46(b)(1)and (50.46(b)(5), the ability of peak cladding temperature to remain below 2200 degreesFahrenheit and sufficient long-term cooling of the reactor core, respectively.In the LAR, STP uses the RELAP-3D code to perform thermal-hydraulic analyses and evaluateLoss-of-Coolant Accidents (LOCAs).The NRC staff requests the licensee to provide the following:1. RELAP-3D input decks for these cases with a 3-D vessel and 1-D core:a. Steady state case in Cold Legb. Medium Break LOCA (6") in Cold Legc. Double-Ended Guillotine (DEG) Break in Cold Legd. Core blockage input file2. RELAP-3D input decks for these cases with a 3-D vessel and 3-D core:a. Steady state case in Cold Legb. Medium Break LOCA (6") in Cold Legc. DEG Break in Cold Leg

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2 NOC-AE- 13003057Page 2 of 3d. DEG Break in Cold Leg with maximum borone. Core blockage input file3. Conversion tables between RETRAN and RELAP-3D ("South Texas Project Power PlantRETRAN-RELAP-3D Conversion Tables")4. Documentation describing model verification ("South Texas Project Power PlantRELAP-3D Steady-state model verification")STPNOC Response:The requested information is provided in the enclosed proprietary digital media. The enclosureincludes 10 DVDs. Disc 1 contains the RELAP5-3D input files and describes the contents of theenclosed mediaThe contents of the media should be withheld from public disclosure. In accordance with1 OCFR2.390, Attachment 1 to the cover letter describes the basis for withholding the proprietaryinformation. As stated in the cover letter and Attachment 1, the information is consideredproprietary in its entirety.As discussed in a teleconference with the NRC staff on January 6, 2014, additional scenarios areincluded to supplement the cases requested in the draft RAI for RELAP5 inputs (referenced inthe cover letter). The following additional files and clarifying information are attached:1. 3-D Vessel and 1-D Core* Small Break LOCA (2") in Cold Leg" Small Break LOCA (2") in Hot Leg" Medium Break (6") in Hot Leg* Double-Ended Guillotine (DEG) Break in Hot Leg2. 3-D Vessel and 3-D Core* Full Core Blockage and Free Core Bypass input file* Full Core Bypass Blockage and Core Blockage except 1 FA at the center inputfile* Full Core and Core Bypass Blockage input file3. Documentation* Input transmittal memo with specific instructions on how to use the input files toexecute core blockage simulations.As discussed in the call, the additional cases form the basis for not only PRA acceptance criteria,but in addition, they demonstrate the safety margin and defense in depth described in thesubmittal (ML13323A183) Enclosure 4-1, Section 2.1 "Defense-In-Depth and Safety Margin".The PRA acceptance criteria for in-vessel effects are partially established by highly conservativesensitivity studies of small, medium, and large breaks in the cold leg and hot leg using theRELAP5 3D vessel, ID core model following recirculation initiation. These cases assumed thatnot only is the core completely blocked but also, the bypass is completely blocked even thoughthere are no major blockage opportunities in the core bypass region. Even when medium and

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2 NOC-AE- 13003057Page 3 of 3large cold leg break scenarios are investigated with open bypass (conservatively ignoring theSTP LOCA holes in the baffle walls), such cases go to success.In Enclosure 4-1, Section 2.1.2 "Safety Margin", more realistic scenarios that used the 3D vessel,3D core model are described where just the flow area of one fuel assemblymaintains corecooling below the failure peak clad temperature (PCT) (800'F). This small flow area would bemuch less than the flow area of the core baffle bypass flow area and the cases demonstrate thatthe PCT is insensitive to the open location.

NOC-AE- 13003057EnclosureRELAP5 digital mediaTen (10) DVDs labeled NOC-AE-13003057 Disc 1 -10