ML11294A341

Oconee Nuclear Station (Ons), Units 1, 2, and 3, Response to Requests for Additional Information Regarding Necessary Modifications to Enhance the Capability of the ONS Site to Withstand the Postulated Failure of the Jocassee Dam

ML11294A341
Person / Time
Site:	Oconee
Issue date:	10/17/2011
From:	Gillespie T P Duke Energy Carolinas
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
TAC ME6133, TAC ME6134, TAC ME6135, FOIA/PA-2012-0128, FOIA/PA-2013-0213
Download: ML11294A341 (17)

Text

This letter contains Security Sensitive Information T. PRESTON GILLESPIE, Jr.Duke Withhold from Public Disclosure under 10 CFR 2.390 Vice Presidentk nergy Oconee Nuclear StationDuke EnergyONOl VP / 7800 Rochester Hwy.Seneca, SC 29672864-873-4478864-873-4208 faxT. Gillespie@duke-energy. comOctober 17, 2011U.S. Nuclear Regulatory CommissionAttn: Document Control DeskWashington, DC 20555-0001

Subject:

Duke Energy Carolinas, LLC (Duke Energy)Oconee Nuclear Station (ONS), Units 1, 2, and 3Renewed Facility Operating License Numbers DPR-38, DPR-47, and DPR-55;Docket Numbers 50-269, 50-270, and 50-287;Response to Requests for Additional Information Regarding NecessaryModifications to Enhance the Capability of the ONS Site to Withstand thePostulated Failure of the Jocassee Dam

References:

1. Duke Energy letter from T. Preston Gillespie to Luis Reyes (Nuclear RegulatoryCommission), Oconee Response to Confirmatory Action Letter (CAL) 2-10-003, datedNovember 29, 20102. Duke Energy letter from T. Preston Gillespie to Victor McCree (Nuclear RegulatoryCommission), Oconee Response to Confirmatory Action Letter (CAL) 2-10-003, datedApril 29, 20113. Nuclear Regulatory Commission (NRC) letter from John Grobe to Preston Gillespie(Duke Energy), Oconee Nuclear Station, Units 1, 2, and 3, Assessment of Duke EnergyCarolinas, LLC's, April 29, 2011, Response to Confirmatory Action Letter RegardingModifications to Address External Flooding Concerns (TAC Nos. ME6133, ME6134, andME6135), dated August 18, 2011By letter dated November 29, 2010 (Reference 1), Duke Energy committed to provide the NRCwith a list of necessary modifications to enhance the capability of-the ONS site to withstand thepostulated failure of the Jocassee Dam. This list of necessary modifications was provided to theNRC in a letter dated April 29, 2011 (Reference 2). Subsequently, the NRC transmitted aRequest for Additional Information (RAI) letter to Duke Energy on August 18, 2011 (Reference3), concerning information provided in the April 29, 2011 letter. The Enclosure to this letterprovides Duke Energy's responses to the NRC RAIs contained in the August 18, 2011 letter(Reference 3).Since this letter and its enclosure contain security sensitive information, Duke Energyhereby requests the NRC to withhold them from public disclosure pursuant to10 CFR 2.390(d)(1), "Public inspections, exemptions, requests for withholding."www. duke-energy corn Security Sensitive Information -Withhold From Public Disclosure Under 10 CFR 2.390U.S. Nuclear Regulatory CommissionOctober 17, 2011Page 2This letter contains no new regulatory commitments. If there are any questions regarding thissubmittal, please contact Kent Alter, the ONS Regulatory Compliance Group Manager, at(864) 873-3255.I declare under penalty of perjury that the foregoing is true and correct. Executed onOctober 17, 2011.Sincerely,17:eLCS,6'arT. reston Gillespie, Jr.Vice PresidentOconee Nuclear Station

Enclosure:

Response to August 18, 2011 Requests for Additional Information Regarding ONSExternal Flooding Security Sensitive Information -Withhold From Public Disclosure Under 10 CFR 2.390U.S. Nuclear Regulatory CommissionOctober 17, 2011Page 3cc w/

Enclosure:

Mr. Victor McCree, Regional AdministratorU. S. Nuclear Regulatory Commission -Region IIMarquis One Tower245 Peachtree Center Ave., NE, Suite 1200Atlanta, Georgia 30303-1257Mr. John Stang, Project ManagerOffice of Nuclear Reactor RegulationU. S. Nuclear Regulatory CommissionMail Stop 0-8 G9AWashington, DC 20555Mr. Andy SabischSenior Resident InspectorOconee Nuclear SiteMs. Susan E. Jenkins, ManagerRadioactive & Infectious Waste ManagementDivision of Waste ManagementSouth Carolina Department of Health and Environmental Control2600 Bull St.Columbia, SC 29201 Security Sensitive Information -Withhold From Public Disclosure Under 10 CFR 2.390U.S. Nuclear Regulatory CommissionOctober 17, 2011Page 4bcc w/

Enclosure:

L. S. NicholsJ. E. BurchfieldJ. A. KammerR. J. FreudenbergerT. L. PattersonK. R. AlterR. H. GuyC. J. Thomas -GOR. D. Hart -CNSK. L. Ashe -MNSNSRB, ECOSNELL, EC050ONS Document Management Security Sensitive Information -Withhold From Public Disclosure Under 10 CFR 2.390ENCLOSUREResponse toAugust 18, 2011 Requests for Additional InformationRegarding ONS External Flooding Security Sensitive Information -Withhold From Public Disclosure Under 10 CFR 2.390Enclosure -Response to RAIs Regarding External FloodingOctober 17, 2011Page 2 of 13Response to August 18, 2011 Requests for Additional InformationRegarding ONS External FloodingDuke Energy's responses to NRC RAls documented in the August 18, 2011 letter regardingONS external flooding are provided in this enclosure. Please note that the 'number' assigned toeach RAI corresponds to the sequence of the 'bulleted' items from the NRC August 18, 2011letter.NRC RAI 1:Provide justification for the statement in your April 29, 2011, letter that the postulated failure ofthe Jocassee Dam is considered a beyond design basis event.Response:Within the April 29, 2011 letter (Response Reference 1), the statement related to the postulatedfailure of the Jocassee Dam being beyond design basis was a historical discussion relative tothe Updated Final Safety Analysis Report (UFSAR) Criterion 2. From a historic perspective, thefailure of the Jocassee Dam was not postulated within the Oconee licensing or design basis andtherefore, would have been a beyond design basis event. As discussed in previouscorrespondence and below, Duke Energy plans to incorporate external flooding resulting from apostulated Jocassee Dam failure into the Oconee licensing basis.With regard to the Jocassee Dam, Oconee Nuclear Station (ONS) remains in full compliancewith its original design and licensing basis. There are two potential failures considered for theJocassee Dam in the original licensing basis for ONS. These separate failures are associatedwith overtopping of the dam due to Probable Maximum Precipitation (PMP) and application ofseismic loads to the Jocassee Dam. The PMP induced external flooding analysis shows thatthe Jocassee project is designed with adequate margin to contain and control floodwaterswithout resulting in a failure of the Jocassee Dam (Reference UFSAR Section 2.4.2). Inaddition, Jocassee Dam is designed to ensure an adequate factor of safety under postulatedseismic design criteria. As such, no failures of the Jocassee Dam are assumed under seismicconditions (Reference UFSAR Section 2.4.4). Consequently, the postulated failure of theJocassee Dam for purposes of the licensing basis revision does not have an initiating event(Response Reference 6).Duke Energy submitted a supplemental response to Generic Letter No. 83-28 on April 12, 1995(Response Reference 3) which described the ONS licensing basis and general criteria forclassifying QA-1 systems, structures, and components (SSCs). The QA-1 designation definedin the Duke Energy Quality Assurance Program Topical Report (Response Reference 4) isanalogous to the term safety related. The Duke Energy Topical Report describes how 10 CFR50, Appendix B is implemented at Oconee. Attachment 4, "Oconee Licensing Position on NonQA-1 SSCs Which are Used to Mitigate Accidents," is included in the April 12, 1995 letter. Highwind, external flooding, and seismic events are included in Attachment 4a which describesevents which are treated as design criteria to provide a high level of confidence that theequipment needed to safely shut down the plant will remain functional. The conclusion that Security Sensitive Information -Withhold From Public Disclosure Under 10 CFR 2.390Enclosure -Response to RAIs Regarding External FloodingOctober 17, 2011Page 3 of 13these events are considered design criteria rather than design basis events is included in theNRC Safety Evaluation dated August 3, 1995, (Response Reference 5) issued in response toDuke Energy's April 12, 1995 response (Response Reference 3).Duke Energy letter dated April 12, 1995 (Response Reference 3) described the events treatedas QA-1 and Non QA-1. Attachment 4a of this letter defined external flooding as design criteriathat was not included in the QA or augmented QA program. This position is consistent with theNRC review documented in the associated NRC Safety Evaluation dated August 3, 1995(Response Reference 5).Duke Energy has decided to enhance the overall safety performance of ONS through theimplementation of modifications to address external plant flooding conditions. Thesemodifications, considered safety enhancements, would be designed to withstand the effects of apostulated failure of the Jocassee Dam to provide reasonable assurance that:" The three Oconee units can be safely shut down and maintained in a safe shutdowncondition, and* The two spent fuel pools can be maintained in a safe condition.Similar to the site PMP, external flooding as a result of a postulated Jocassee Dam failure is tobe treated as a design criterion, not a design basis event. External flooding is not included as adesign basis event within the existing Oconee licensing basis. The distinction between thetreatment of external flooding at ONS as a design criterion rather than a design basis event isinherent in documentation within ONS UFSAR Chapter 15 (accident analysis chapter). ThisUFSAR chapter states, "This section details the expected response of the plant to the spectrumof transients and accidents which constitute the design basis events." High wind, externalflooding, and seismic events are not included in UFSAR Chapter 15, and therefore, are treatedas design criteria.As with the implementation and licensing of other safety enhancements at ONS (i.e., StationBlackout, Anticipated Transient without Scram), it is consistent to classify these enhancementsas beyond design basis events.Duke Energy plans to incorporate these modifications into the licensing basis through an updateof the UFSAR in accordance with the requirements of 10 CFR 50.71, "Maintenance of records,making or reports," and 10 CFR 50.59, "Changes, tests, or experiments," or 10 CFR 50.90,"Application for amendment of license, construction permit, or early site permit," as appropriate.10 CFR 50.71(e) requires that the description of new analysis of issues affecting safety beincluded in the UFSAR. As such, Duke Energy plans to include a description of the analysis inUFSAR Chapter 2.4, "Hydrologic Engineering" as well as conforming changes to other sectionsof the UFSAR, as appropriate. This is consistent with our previous correspondence in the letterdated July 9, 2009 (Response Reference 2). Upon completion of the UFSAR update, externalflooding associated with the postulated Jocassee Dam failure will be included in the licensingbasis as a design criterion.

Security Sensitive Information -Withhold From Public Disclosure Under 10 CFR 2.390Enclosure -Response to RAIs Regarding External FloodingOctober 17, 2011Page 4 of 13NRC RAI 2:Provide clarification that natural phenomena are not design basis events at ONS (i.e., highwinds, external flooding, and seismic events).Response:Oconee Nuclear Station (ONS) was designed, constructed, and licensed to design criteria thatare described in the ONS UFSAR and predate 10 CFR 50, Appendix A, "General DesignCriteria for Nuclear Power Plants," and the use of the term design basis event. Based onregulations that were in place during original ONS licensing, Oconee's license relies on featuresthat are safe and effective, were approved by the NRC, but that are not always consistent withthe NRC Standard Review Plan.There are two potential failures considered for the Jocassee Dam in the original licensing basisfor ONS. These separate failures are associated with overtopping of the dam due to ProbableMaximum Precipitation (PMP) and application of seismic loads to the Jocassee Dam. The PMPinduced external flooding analysis shows that the Jocassee project is designed with adequatemargin to contain and control floodwaters without resulting in a failure of the Jocassee Dam(Reference UFSAR Section 2.4.2). In addition, Jocassee Dam is designed to ensure anadequate factor of safety under postulated seismic design criteria. As such, no failures of theJocassee Dam are assumed under seismic conditions (Reference UFSAR Section 2.4.4).Consequently, the postulated failure of the Jocassee Dam for purposes of the licensing basisrevision does not have an initiating event (Response Reference 6).The postulated failure of the Jocassee Dam has no initiating event and would result in externalflooding at ONS. External flooding is addressed within the licensing basis for Oconee. Forexample, external flooding as a result of PMP is classified as design criteria within the Oconeelicensing basis. As such, Duke Energy proposes treatment of these mitigating features in amanner consistent with the Oconee licensing basis.Generic Letter No. 83-28, "Required Actions Based on Generic Implications of Salem ATWSEvents," addressed four specific areas including the programs for ensuring that all componentsnecessary for accomplishing required safety-related functions are properly identified indocuments, procedures, and information handling systems that are used to control safetyrelated plant activities. Duke Energy submitted a supplemental response to Generic LetterNo. 83-28 on April 12, 1995 (Response Reference 3) which described the ONS licensing basisand general criteria for classifying QA-1 systems, structures, and components (SSCs). TheQA-1 designation defined in the Duke Energy Quality Assurance Program Topical Report(Response Reference 4) is analogous to the term safety related. The Duke Energy TopicalReport describes how 10 CFR 50, Appendix B is implemented at Oconee.Attachment 4, "Oconee Licensing Position on Non QA-1 SSCs Which are Used to MitigateAccidents," is included in the April 12, 1995 letter. High wind, external flooding, and seismicevents are included in Attachment 4a which describes events which are treated as designcriteria to provide a high level of confidence that the equipment needed to safely shut down theplant will remain functional. The conclusion that these events are considered design criteria Security Sensitive Information -Withhold From Public Disclosure Under 10 CFR 2.390Enclosure -Response to RAls Regarding External FloodingOctober 17, 2011Page 5 of 13rather than design basis events is included in the NRC Safety Evaluation dated August 3, 1995(Response Reference 5), issued in response to Duke Energy's April 12, 1995 response(Response Reference 3).The distinction between the treatment of natural phenomena at ONS as design criteria ratherthan design basis events is also inherent in documentation within ONS UFSAR Chapter 15(accident analysis chapter). This UFSAR chapter states, "This section details the expectedresponse of the plant to the spectrum of transients and accidents which constitute the designbasis events." High wind, external flooding, and seismic events are not included in UFSARChapter 15, and therefore, are treated as design criteria.NRC RAI 3:Provide justification for the assumptions used in the development of the mitigating strategiesand the entry conditions associated with each phase of the mitigation strategies.Response:The following licensing and design basis inputs and assumptions have been defined for thepostulated failure of the Jocassee Dam:Design and Licensing Basis Inputs and Assumptions:1. No initiating event is assumed for the postulated failure of the Jocassee Dam.2. No single active or passive failure is assumed in addition to the postulated failure of theJocassee Dam. The failure of a control rod to fully insert is not assumed.3. The postulated failure is not combined with any other design criteria, design basis event,operational occurrence, transient, or design basis accident.4. The external flood mitigating features will not be seismically designed.5. This postulated failure of the Jocassee Dam is not treated as a design basis event. (Seeresponse to RAI 1 for justification).6. Inputs and assumptions associated with inundation analyses are in accordance with thebase case (Case 2) as reviewed by the NRC in the Safety Evaluation dated January 28,2011 (Response Reference 6).It should be noted that in executing the detailed design of the passive mitigating features for apostulated failure of the Jocassee Dam a number of calculations and analyses will have to beperformed. These calculations will adopt the design and licensing basis inputs and assumptionslisted above, as appropriate. In addition, a number of other inputs and assumptions will bemade in completing this analytical work. These inputs and assumptions will be reasonable andappropriate for their use and will be justified and documented in calculations and analyses thatwill be available for NRC inspection.The PMP induced flood studies showed that both Lake Jocassee and Lake Keowee weredesigned with adequate margin to contain and control flood waters (Reference UFSAR section2.4.2). In addition, the Keowee Dam, Little River Dam, Jocassee Dam, and the Intake CanalDike have been designed to have an adequate factor of safety under the same conditions ofseismic loading used in the design of Oconee (Reference UFSAR section 2.4.4). As a result, a Security Sensitive Information -Withhold From Public Disclosure Under 10 CFR 2.390Enclosure -Response to RAIs Regarding External FloodingOctober 17, 2011Page 6 of 13postulated failure of the Jocassee Dam with no accident initiator is being added to the Oconeelicensing basis as a design criterion (Response Reference 6).The design basis events for Oconee are addressed in Chapter 15 of the UFSAR. Each event isconsidered individually without the concurrence of other events. The Loss of Off-site Power(LOOP) is not listed as a design basis event. However, a LOOP was a consideration for certaindesign basis events. The design basis events that consider a concurrent LOOP are the loss ofcoolant accident and the main steam line break.As such, it is consistent with the ONS licensing basis to treat this postulated failure individuallywithout combination with other design criteria or design basis events such as LOOP or seismicactivity.The external flooding from a postulated Jocassee Dam failure will not be combined with anyother single active or passive failure. This conclusion is consistent with the ONS licensingbasis.The entry conditions associated with each phase are described in the response to the RAI 4.NRC RAI 4:Provide a summary of the sequence of actions for achieving each phase of the mitigatingstrategies. Identify when each operator action has to be completed. In addition, demonstratethat the sequence of events would not result in unacceptable radiological consequences.Identify and justify the selected acceptance criteria, and provide a detailed description of theanalyses performed to support the conclusion.Response:The following response is based on the committed modifications being implemented. Thesequence of actions is also based on preliminary analyses. Procedures have not yet beenwritten to address the required operator actions. The following discussion of operator actions isintended to provide an overview of the strategy that may be employed post dam failure.The mitigation of a postulated failure of the Jocassee Dam has been divided into three distinctphases based on the potential consequences. The first phase was established as thepostulated failure of the Jocassee Dam itself. Monitoring activities performed by Duke Energypersonnel at the Jocassee Hydroelectric Station result in notification to ONS regarding potentialdegradation and/or failure of the dam using the Jocassee Hydroelectric Station emergencyaction plans. Once notifications have been received at ONS actions are taken to provide aprotected offsite AC power source to ONS. In addition, actions are taken to protect the yard(elevation 796'), the turbine building, and the auxiliary building from potential flooding that mayresult if the Keowee Dam and the Intake Canal dike are overtopped following the Jocassee Damfailure. Additional actions are to be taken to protect and conserve the water in the condensercirculating (CCW) water system to conserve the stored inventory should the Keowee Dam andthe Intake Canal dike fail after overtopping occurs. Finally, the operators would take actions toplace all three ONS units in hot standby with reactor coolant system (RCS) temperature at Security Sensitive Information -Withhold From Public Disclosure Under 10 CFR 2.390Enclosure -Response to RAIs Regarding External FloodingOctober 17, 2011Page 7 of 13approximately 555°F and RCS pressure at approximately 2155 psig. Normal plant systemsremain available during this phase to maintain these conditions. Calculations indicate that two(2) hours would be available to complete these actions prior to overtopping of the Keowee Dam.Operators may initiate boration of the RCS from either the concentrated boric acid storage tank(CBAST) or from the borated water storage tank (BWST) while normal systems remainavailable.When overtopping of the Keowee Dam and the Intake Canal dike occurs, the integrity of thedam and dike can no longer be assured. The failure of the Keowee Dam was assumed to resultin the loss of both Keowee Hydroelectric Units and all of the unprotected offsite power sources(including the 230kV Switchyard). This results in a momentary loss of power until power isautomatically restored from the protected offsite power source established in the first phase.Main feedwater (MFW) pumps and the reactor coolant pumps would be lost as a consequence.In addition, cooling for the spent fuel pools (SFP) would be lost. This marks the transition to thesecond phase of the scenario.Operators would initiate the Loss of Power Abnormal Procedure to verify proper electrical loadtransfers and to reestablish power to needed equipment that experienced a load shed. Theemergency feedwater (EFW) pumps would have automatically started due to the loss of themain feedwater pumps. Steam generator (SG) levels would be automatically controlled at thenatural circulation setpoint. Operator action would be taken to control the makeup flow to theRCS using the high pressure injection (HPI) system. Natural circulation conditions would beverified. Actions would also be initiated to stop the low pressure service water (LPSW) pumps.This action would also require the motor-driven EFW pumps to be stopped. The EFW functionwould be maintained by the turbine-driven EFW pump. The elevated water storage tank(EWST) would provide cooling for the turbine-driven EFW pump and the HPI pump motorcoolers. The high pressure service water (HPSW) jockey pump would be operated asnecessary to maintain water level in the EWST. Actions would be taken to monitor the SFP fortemperature and level.At this point it would be clear that reactor coolant pumps could not be restored. Consequently,a natural circulation cooldown would be initiated. Operators would be required to borate theRCS by aligning HPI pump suction to the BWST and by opening the reactor vessel (RV) headvents. If no boration occurred during the first phase, boration using the RV head vents couldrequire approximately 1.5 to 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> to complete sufficient boration of the RCS to initiate a plantcooldown. Operators would be dispatched to operate the atmospheric dump valves to initiateRCS cooldown. The RV head vents are required to remain open while performing a naturalcirculation cooldown at the maximum allowable cooldown rate to preclude void formation in theRV head. The HPI pumps would be operated to provide makeup to the RCS to compensate fordensity changes in the RCS as well as for inventory losses through the RV head vents. Suctionfor the HPI pumps would be provided by the BWST. The BWST will provide sufficient borationof the RCS to maintain adequate shutdown margin for the RCS cooldown. The pressurizerheaters would be de-energized and the power-operated relief valve (PORV) would be cycled, asnecessary, to reduce RCS pressure during the natural circulation cooldown. When the mainsteam (MS) pressure is reduced to approximately 250 psig, the standby shutdown facility (SSF)auxiliary service water (ASW) system would be placed into service to feed the SGs to continue Security Sensitive Information -Withhold From Public Disclosure Under 10 CFR 2.390Enclosure -Response to RAIs Regarding External FloodingOctober 17, 2011Page 8 of 13the natural circulation cooldown. RCS cooldown and depressurization continues until RCStemperature is approximately 250°F and RCS pressure is approximately 300 psig.The transition to the third phase is marked by the RCS having been cooled to approximately2500F. At this point, the RV head vents are closed and the HPI pumps are stopped. RCSboron concentration would be sufficient to maintain adequate shutdown margin for an RCStemperature of 2000F. RCS pressure would be maintained such that adequate subcoolingmargin is maintained in the reactor core and the high points of the RCS loops. The SSF ASWsystem remains in operation to control SG water levels at the natural circulation setpoint toremove core decay heat. Water level in the SFP would continue to be monitored with makeupestablished and controlled. SFP makeup would be required within 36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br /> following the loss ofspent fuel cooling. Proper control of water level in the pool will provide sufficient radiationshielding from the spent fuel as well as maintain adequate heat removal from the spent fuel.In each of the phases, the mitigation strategy maintains the integrity of the reactor coolantpressure boundary as well as protecting the reactor core against fuel failures. In the first phase,the reactor and turbine would be shutdown as a precautionary measure. Should a turbine tripoccur, the minimum departure from nucleate boiling ratio (DNBR) remains above the designlimit and RCS pressure does not exceed 110% of design pressure. In the second phase, a lossof reactor coolant pumps and main feedwater pumps would be expected; however, unlike thefirst phase, the reactor has already been shut down. The loss of reactor coolant pumps andmain feedwater pumps has been previously analyzed assuming the reactor was operating at fullpower. The results of that analysis showed that the minimum DNBR remained above thedesign limit and RCS pressure did not exceed 110% of design pressure. The results with thereactor operating at full power would bound the results with the reactor already shutdown.Adequate core cooling will be maintained during natural circulation. Since the RCS pressureboundary and the nuclear fuel are protected against failure, no unacceptable radiologicalconsequences would occur.NRC RAI 5:Provide justification for not installing the modifications, to enhance the capability of the ONS siteto mitigate the postulated failure of the Jocassee Dam, in accordance with the Title 10 of theCode of Federal Regulations, Appendix B, quality assurance criteria.Response:The Duke Energy Quality Assurance Program Topical Report (Response Reference 4)describes how 10 CFR 50, Appendix B is implemented for the Duke Energy Fleet. The TopicalReport is NRC approved and describes a graded quality assurance (QA) program in which theQA-1 designation is considered analogous to safety related.Duke Energy letter dated April 12, 1995 (Response Reference 3) described the events treatedas QA-1 and Non QA-1. Attachment 4a of this letter defined external flooding as design criteriathat was not included in the QA or augmented QA program. This position is consistent with theNRC review documented in the associated NRC Safety Evaluation dated August 3, 1995.(Response Reference 5).

Security Sensitive Information -Withhold From Public Disclosure Under 10 CFR 2.390Enclosure -Response to RAIs Regarding External FloodingOctober 17, 2011Page 9 of 13The SSCs designed, procured, constructed, and operated to mitigate external flooding due to apostulated failure to the Jocassee Dam are not required to be classified as safety related. Aswith any modifications, design control processes applied will evaluate impacts, such asinteractions with existing SSCs, and apply appropriate quality standards.Although the Jocassee Dam failure mitigative features are not required to be nuclear safetyrelated, assurance of the mitigative features' capability is provided in design, construction, andmaintenance by Duke Energy and regulatory processes.The means by which the mitigative features' capability is assured by Duke Energy processesare described as follows:" With respect to design and construction, the new SSCs are to be designed utilizingapplicable industry and regulatory design criteria, as appropriate. The documentation ofthe design capabilities of the Jocassee Dam failure mitigative features are to becaptured within Duke Energy analyses. Industry accepted codes and standards used inestablishing the design and operation of the external flood mitigation features will also bedocumented within Duke Energy analyses. The internal standards associated withanalyses are prescribed by corporate directive EDM-1 01, "EngineeringCalculations/Analyses." EDM-101 provides assurance that analyses are auditable,retrievable, and technically correct. The records associated with this activity will beavailable for NRC inspection.* The critical aspects of generally accepted design criteria are captured within DukeEnergy Design Specifications associated with procurement and construction. Thecritical aspects are defined from an inspectability and testability perspective as criticalcharacteristics. During material procurement and construction, the critical characteristicsfrom the Duke Energy Design Specifications are captured as acceptance criteria withinreceipt inspection and construction procedures to ensure the quality of the final designmatches the critical aspects of the associated SSC design criteria.0 The modifications will be installed in accordance with procedures by individuals who arequalified to perform their tasks. The design of the Jocassee Dam failure mitigativefeatures will be conducted under the same procedures that are used to conduct safetyrelated analysis. The records associated with this activity will be available for NRCinspection.* Update of the licensing and design basis will capture the criteria and analyses justifyingthe capabilities described for the Jocassee Dam failure mitigative features. The additionof the mitigative features to the design basis provides assurance that the criticalassumptions, initial conditions, and equipment capabilities are tested and maintainedthrough station preventive maintenance and testing programs.* The design and licensing basis addition provides assurance that details of the JocasseeDam failure mitigative features are properly captured and utilized within stationprocedures. The internal standards associated with procedures are prescribed by Security Sensitive Information -Withhold From Public Disclosure Under 10 CFR 2.390Enclosure -Response to RAIs Regarding External FloodingOctober 17, 2011Page 10 of 13corporate directive NSD-703, "Administrative Instructions for Technical Procedures".NSD-703 provides assurance that the procedures are safe and effective.In addition, the mitigative features' capability is assured by existing regulatory processes.Examples are as follows:" From a site risk perspective, tracking and trending of maintenance and unavailability ofmitigating equipment are performed in accordance with 10 CFR 50.65. This programensures that the effectiveness of maintenance is evaluated to provide reasonableassurance that structures, systems, and components are capable of fulfilling theirintended functions regardless of quality assurance classification. Furthermore, the10 CFR 50.65 program requires risk management with appropriate contingencies in theevent that SSCs become unavailable due to either planned or corrective maintenance." The addition of the Jocassee Dam failure mitigative features to the ONS licensing basisprovides assurance of their long term maintenance. As stated in this letter, theJocassee Dam failure mitigative features are to be added to the UFSAR therebyincorporating it within the licensing basis subject to considerations of regulatory relatedprocesses such as 10 CFR 50.59 and functionality (NRC Inspection Manual Part 9900).These processes provide assurance that features are evaluated, restored, andmaintained as appropriate.NRC RAI 6:Provide a description of the standards used in the development of the calculations and the newprocedures to support your mitigating strategies.Response:The Jocassee Dam failure mitigative features that Duke Energy plans to implement at ONS willbe designed, procured, constructed, and operated in accordance with the applicable regulatoryand industry standards, as appropriate. The records associated with this activity will beavailable for NRC inspection.These standards will be identified during the design, procurement, work planning, andprocedural development phases of this project. The Duke Energy response to NRC RAI 7provides a schedule defining future activities. The detailed design phase is initiated at T1 andspans through T12. Procurement, work planning, and procedural development activities willspan through the Regulatory Review Period and into the construction phase.These standards will be documented in design, procurement, and construction records(calculations, drawings, specifications, modifications packages, and work orders). Standardrequirements that impact operations will be contained in the procedures used to operate thefacility.These activities will be executed in accordance with procedures by trained individuals who arequalified to perform their tasks. The design of the Jocassee Dam failure mitigative features will Security Sensitive Information -Withhold From Public Disclosure Under 10 CFR 2.390Enclosure -Response to RAIs Regarding External FloodingOctober 17, 2011Page 11 of 13be conducted under the same procedures that are used to conduct safety related analysis. Therecords associated with this activity will be available for NRC inspection.Design requirements will identify critical characteristics that are translated into specifications forthe procurement of materials, the inspection and testing of materials, and the inspection andtesting of construction activities. These requirements will be documented in records that areavailable for NRC inspection.NSD-703, "Administrative Instructions for Technical Procedures," guides the development ofprocedures and will provide assurance that the critical design and licensing requirements aretranslated into procedural guidance.NRC RAI 7:Provide a schedule for the modifications with identification of key elements. Include justificationfor time required to implement the modifications.Response:The following milestone schedule identifies key elements of the design, procurement, andconstruction processes required to execute the major construction of the project and bound theoverall project timeline of modifications. Details of the content of each activity are provided todefine the specific activities contained in each milestone. (Notes associated with the milestoneschedule follow the schedule.)TO Resolution of all requests for additional information (RAIs) on Duke EnergyConfirmatory Action Letter (CAL) 2-10-003 dated April 29, 2011 (ResponseReference 1)T1 Initiation of detailed engineering based on finalized design scope. Detailedengineering will consist of the development, review and approval of calculations,design drawings, 10 CFR 50.59s and other associated supporting documentationT12 Submittal of Detailed Design including calculations and detailed drawings toFederal Regulatory Energy Commission (FERC) for reviewT15 Submittal of License Amendment Request (LAR) to NRC based on the designattributes not covered by the 10 CFR 50.59 review process. The LAR submittalwill address impacts to the internal flooding analysisRRP Regulatory Review Period (RRP)T15 + RRP Begin Construction Activities; construction is expected to require 15 months ofeffortT30 + RRPCompletion of Construction Activities Security Sensitive Information -Withhold From Public Disclosure Under 10 CFR 2.390Enclosure -Response -to RAIs Regarding External FloodingOctober 17, 2011Page 12 of 13Notes:1) All milestones are preliminary and are subject to change as the engineering design packageand the field implementation plans are developed and executed.2) All durations are expressed in months, i.e., T12 = twelve (12) months after resolution of allrequested additional information.3) Design and Construction durations are based on the design inputs and assumptionsdescribed in this response. Changes to design inputs and assumptions may result in animpact to the schedule and to the approach for addressing this postulated failure ofJocassee Dam.4) The T30 schedule assumes that the key assumptions made by Duke Energy, as defined inthe April 29, 2011 (Response Reference 1) CAL responses, do not change as part of theregulatory review process.5) It is assumed that at the end of the Regulatory Review Period that Duke Energy has all ofthe necessary NRC and FERC approvals to proceed with the construction activity.The schedule durations are required due to:* Extensive geotechnical exploration and lab analysis for design inputs* Origination, checking and approval of detailed design calculations and designdrawings* Development of regulatory approval submittals (internal flooding analysis, securityplan, etc.)* Requisition of long lead time materials / equipment* Resolution of interactions with security related equipment and plant structures,systems and components* Identification and remediation of existing underground commodities interferences* Development of modification work packages* Planning and scheduling of modification work packages* Recruitment, training, and qualification of a large technical and implementationworkforce* The scope of the construction activity* Managing the Security / Safety interface with construction activities* Resolution of unanticipated interferences / interaction / conflicts Security Sensitive Information -Withhold From Public Disclosure Under 10 CFR 2.390Enclosure -Response to RAIs Regarding External FloodingOctober 17, 2011Page 13 of 13Response References1. Duke Energy letter from T. Preston Gillespie to Victor McCree (Nuclear RegulatoryCommission), Oconee Response to Confirmatory Action Letter (CAL) 2-10-003, datedApril 29, 20112. Duke Energy letter from Dave Baxter to NRC Document Control Desk, Oconee Final60-Day Response to NRC Letter from Joseph G. Giitter to Dave Baxter, datedJuly 9, 20093. Duke Energy letter from J.W. Hampton to NRC Document Control Desk, Oconee QA-1Licensing Basis and Generic Letter 83-28, Section-2.2. 1, Subpart 1 SupplementalResponse, dated April 12, 19954. Duke Energy Carolinas Topical Report Quality Assurance Program, September 30, 20115. Safety Evaluation by the Office of Nuclear Reactor Regulation Supplemental Responseto Subpart 1 of Section 2.2.1 of Generic Letter 83-28 General Criteria for ClassifyingQA-1 for Structures, Systems, and Components, dated August 3, 19956. Safety Evaluation by the Office of Nuclear Reactor Regulation related to Duke EnergyCarolinas, LLC, Confirmatory Action Letter -Commitments to Address External FloodingConcerns, Closure of Inundation Site Results, Oconee Nuclear Station Units 1, 2, and 3(ONS), dated January 28, 2011