ML091870501

Proposed License Amendment Request No. 2008-007 to Revise the Current Licensing Basis for High Energy Line Break Events Outside of the Containment Building

ML091870501
Person / Time
Site:	Oconee
Issue date:	06/29/2009
From:	Baxter D Duke Energy Carolinas
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
LAR 08-007
Download: ML091870501 (17)

Text

Duke EneDuke DAVE BAXTER Vice President PakEnergy Oconee Nuclear Station Duke Energy ON01 VP / 7800 Rochester Highway Seneca, SC 29672 864-873-4460 864-873-4208 fax dabaxter@dukeenergy.com June 29, 2009 U. S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, D. C. 20555-0001

Subject:

Duke Energy Carolinas, LLC Oconee Nuclear Station, Unit 3 Renewed Facility Operating License Number DPR-55 Docket Number 50-287 "Proposed License Amendment Request to Revise the Oconee Nuclear Station Current Licensing Basis for High Energy Line Break Events Outside of the Containment Building,"

License Amendment Request No. 2008-007

References:

1. Letter to Mr. James Dyer, Director, Office of Nuclear Reactor Regulation, from Henry B.

Barron, Group Vice President and Chief Nuclear Officer, Nuclear Generation, Duke Energy Corporation, "Tornado/HELB Mitigation Strategies and Regulatory Commitments," dated November 30, 2006.

2. Letter from Leonard N. Olshan, Project Manager, Plant Licensing Branch II-1, Division of Operating Reactor Licensing, Office of Nuclear Reactor Regulation, "Summary of March 5, 2007, Meeting to Discuss the November 30, 2006, Letter Regarding Oconee High-Energy Line Break (HELB) and Tornado Mitigation Strategies," dated March 28, 2007.

3. Letter. from Leonard N. Olshan, Project Manager, Plant Licensing Branch 11-1, Division of Operating Reactor Licensing, Office of Nuclear Reactor Regulation, "Summary of March 20, 2007, Meeting to Discuss Oconee High-Energy Line Break (HELB)

Mitigation Strategy," dated April 3, 2007.

4. Letter from Timothy J. McGinty, Deputy Director, Division of Operating Reactor Licensing, USNRC Office of Nuclear Reactor Regulation, to Bruce H. Hamilton, Oconee Nuclear Station, Units 1, 2, and 3 (Oconee) - Tornado and High-Energy Line Break (HELB) Mitigation Strategies, dated May 15, 2007.

5. Letter to the U. S. Nuclear Regulatory Commission from Henry B. Barron, Group Vice President and Chief Nuclear Officer, Ndclear Generation, Duke Energy Corporation, "Revision to Tornado/HELB Mitigation Strategies and Regulatory Commitments," dated January 25, 2008.

www. duke-energy, com

Nuclear Regulatory Commission License Amendment Request No. 2008-007 June 29, 2009 Page 2

6. Letter to the U. S. Nuclear Regulatory Commission from David Baxter, Vice President, Oconee Nuclear Station, Duke Energy Corporation, "Proposed License Amendment Request to Revise the Oconee Nuclear Station Current Licensing Basis for HELB events outside of the Containment Buildings; License Amendment Request No. 2008-005,"

dated June 26, 2008.

7. Letter to the U. S. Nuclear Regulatory Commission from Dave Baxter, Vice President, Oconee Nuclear Station, Duke Energy Corporation, Revision to Tornado/HELB Strategies and Regulatory Commitments," dated November 18, 2008.

8. Letter to the U. S. Nuclear Regulatory Commission from Dave Baxter, Vice President, Oconee Nuclear Station, Duke Energy Corporation, "Proposed License Amendment Request to Revise the Oconee Nuclear Station Current Licensing Basis for HELB Events outside of the Containment Building - Unit 2; License Amendment Request No: 2008-006," dated December 22, 2008.

In accordance with 10 CFR 50.90, Duke Energy Carolinas, LLC, (Duke) proposes to amend Renewed Facility Operating License No. DPR-55. This License Amendment Request (LAR) is a continuation of the information sent in the June 26, 2008, LAR 2008-005 (Reference 6) and in the December 22, 2008, LAR 2008-006 (Reference 8). This LAR applies to Unit 3 of the Oconee Nuclear Station (ONS). All non-unit specific information, all generic commitments, and proposed generic modifications submitted in LARs 2008-005 and 2008-006, also apply to this LAR. This LAR will result in a complete revision of the ONS Current Licensing Basis (CLB) in regard to mitigating High Energy Line Break (HELB) events occurring outside of containment for Unit 3.

The proposed changes are the result of an extensive and comprehensive HELB analysis and include several plant modifications necessary to support the revised HELB Licensing Basis (LB).

Included in the proposed changes are the Unit 3 sections of the ONS HELB Report, ONDS-351, Revision 2, and "Analysis of Postulated High Energy Line Breaks (HELBs) Outside of Containment." For this LAR, the ONS Unit 3 portion of the existing HELB Report, MDS Report No. OS-73.2, dated April 25, 1973, and its supplements dated June 22, 1973, and March 12, 1974, respectively, are superseded by Oconee Report ONDS-351, Revision 2. However, the existing HELB report will remain credited until the ONDS-351 Revision 2 report, has been fully implemented, including the incorporation of the proposed modifications.

The enclosed Revision 2 to ONDS-351 includes the Safe Shutdown Analyses for HELBs postulated on the Unit 3 High Energy Piping lines and the Unit 3 specific information for other sections of the HELB report. Those analyses in this revision of ONDS-351 credit normal plant equipment, the Standby Shutdown Facility (SSF), and the new Protected Service Water (PSW) system to achieve safe shutdown. The report also credits the proposed use of the Main Steam Isolation Valves (MSIV), whenever a postulated break is determined to affect the Main Steam pressure boundary and the safe shutdown strategy relies on the SSF. The scenarios using the

Nuclear Regulatory Commission License Amendment Request No. 2008-007 June 29, 2009 Page 3 SSF/MSIVs for Main Steam Line breaks are described in Section 7.0 and the MSIVs are described in Section 3.0 of ONDS-351.

This LAR includes a supplementary list of regulatory commitments in Attachment 1 made as a result of the analyses of the Unit 3 postulated HELBs. This supplementary list is in addition to those commitments made in References 5, 6, and 8, and partially revised in Reference 7. contains the list of the sections of ONDS-351 to be added or replaced. An identification of the reason for each change is also provided in this attachment. Attachments 3 and 4 contain the changes to the UFSAR pages and the Technical Specification (TS) pages. These changes are necessary to include the applicability of Unit 3.

A technical evaluation of the proposed changes is contained in Enclosure 1. Enclosure 2 contains Revision 2 of ONDS-35 1. This revision of the report incorporates the HELB interactions resulting from postulated breaks on Unit 3 high energy piping, adds the MSIV description, and includes the use of the SSF/MSIV for postulated Main Steam Line HELBs. Revision 2 of ONDS-351 also updates all other text sections of the report to remove any inconsistencies amongst the unit evaluations and correct any identified minor errors, typos, and omissions. The only portions of the HELB Report that are not being reissued are those portions of the Units 1 and 2 tables and figures referenced in sections 4.1, 4.2, 5.1, and 5.2, which do not require revision, and hence are identical to their transmittal in the. previous LAR submittals (References 6 and 8).

As described herein, the revised ONS HELB LB is based on the plant configuration that will exist after implementation of modifications to the site as described in various correspondence with the Staff and in this LAR (Ref.: 1, 2, 3, 4, 5, 6, 7, and 8). Accordingly, implementation of the revised HELB LB will be integrated with the completion of those associated plant modifications. As part of modification implementation, certain emergency procedures, pertaining to HELB mitigation and plant safe shutdown, will be revised to include the use of the new systems and methodology.

As noted in the commitment table, the completion for some of the proposed HELB modifications will be contingent upon the staff s approval of the revised HELB methodology. Duke requests approval of this amendment by July 2010, with an extended implementation period in accordance with the listing of commitments given in Attachment 1, References 5, 6, and 8.

The specific actions that Duke will be implementing have been selected and prioritized based upon a thorough assessment of operational risk and safety benefits as well as regulatory considerations and resource requirements. These actions will require a significant investment of resources by Duke and are intended to resolve outstanding HELB LB issues. Duke believes these actions collectively represent the most appropriate use of resources to enhance safety and resolve regulatory issues. Implementation of the revised HELB LB and the related commitments will revise the HELB CLB to address issues raised by the NRC and to collectively enhance the.

station's overall design, safety and risk margin.

In accordance with Duke administrative procedures that implement the Quality Assurance Program Topical Report, these proposed changes have been reviewed and approved by the Plant Operations Review Committee and Nuclear Safety Review Board. A copy of this LAR is being

Nuclear Regulatory Commission License Amendment Request No. 2008-007 June 29, 2009 Page 4 sent to the State of South Carolina in accordance with 10 CFR 50.91 requirements.

Inquiries on this proposed amendment request should be directed to Stephen C. Newman of the Oconee Regulatory Compliance Group at (864) 873-4388.

I declare under penalty of perjury that the foregoing is true and correct. Executed on June 29, 2009.

Sincerely, Day Baxter, Vice President, Oconee Nuclear Station

Enclosures:

1. Evaluation of Proposed Changes

2. ONDS-351, "Analysis of Postulated High Energy Line Breaks (HELBs) Outside of Containment," Rev. 2 Attachments:

1. List of Regulatory Commitments

2. List of sections added or revised in ONDS-351, Rev. 2, and the reason for the change(s).

3. Marked-up pages: UFSAR and Technical Specification Bases

4. Reprinted pages: UFSAR and Technical Specification Bases.

Nuclear Regulatory Commission License Amendment Request No. 2008-007 June 29, 2009 Page 5 bc w/enclosures and attachments:

Mr. Eric Leeds, Director Nuclear Reactor Regulation U.S. Nuclear Regulatory Commission Mail Stop 7 H4 Washington, D. C., 20555-0001 Mr. Luis Reyes, Regional Administrator U.S. Nuclear Regulatory Commission - Region II Sam Nunn Atlanta Federal Center, 23 T85 61 Forsyth St., SW Atlanta, GA 30303-8931 Mr. John Stang, Project Manager Office of Nuclear Reactor Regulation Mail Stop 0-14 H25 U.S. Nuclear Regulatory Commission Washington, D. C., 20555-0001 Mr. Leonard Wert, Director, DRP U.S. Nuclear Regulatory Commission - Region II Sam Nunn Atlanta Federal Center, 23 T85 61 Forsyth St., SW Atlanta, GA 30303-8931 Mr. Kris Kennedy, Director, DRS U.S. Nuclear Regulatory Commission - Region II Sam Nunn Atlanta Federal Center, 23 T85 61 Forsyth St., SW Atlanta, GA 30303-8931

Nuclear Regulatory Commission License Amendment Request No. 2008-007 June 29, 2009 Page 6 bc w/enclosures and attachments (continued):

Mr. Joseph Giitter, Director Division of Operator Reactor Licensing Office of Nuclear Reactor Regulation U.S. Nuclear Regulatory Commission Mail Stop 8 ElA Washington, D. C., 20555-0001 Mr. Jonathan H. Bartley Chief, Branch 1, DRP U.S. Nuclear Regulatory Commission - Region II Sam Nunn Atlanta Federal Center, 23 T85 61 Forsyth St., SW Atlanta, GA 30303-8931 Mr. Curtis W. Rapp Sr. Project Engineer, Branch 1, DRP U.S. Nuclear Regulatory Commission - Region II Sam Nunn Atlanta Federal Center, 23 T85 61 Forsyth St., SW Atlanta, GA 30303-8931 Mr. Eric Riggs NRC Senior Resident Inspector (Acting)

Oconee Nuclear Station Susan E. Jenkins, Manager Infectious and Radioactive Waste Management, Bureau of Land and Waste Management Department of Health & Environmental Control 2600 Bull Street, Columbia, SC 29201

Nuclear Regulatory Commission License Amendment Request No. 2008-007 June 29, 2009 Page 7 bcc w/enclosures and attachments:

D. M. Jamil R. A. Jones R. C. Meixell T.P. Gillespie, Jr.

J. R. Sumpter L. M. Kanipe S. L. Nader L. F. Vaughn R. M. Glover S. L. Batson J. E. Burchfield R..J. Freudenberger G. K. Mc Aninch A. D. Park T. D. Brown P. M. Donnelly J. E. Smith (NRC Commitment Coordinator)

S. C. Newman W. L. Patton R. E. Hall T. D. Mills R. L. Gill - NRI&IA R. D. Hart - CNS K. L. Ashe - MNS D. Repka NSRB, EC05N ELL, EC050 File - T.S. Working ONS Document Management

ENCLOSURE 1 EVALUATION OF PROPOSED CHANGES

Evaluation of Proposed Changes License Amendment Request No. 2008-007 June 29, 2009 Page 1

Subject:

Proposed License Amendment Request to Revise the Oconee Nuclear Station Current Licensing Basis for High Energy Line Break Events Outside of the Containment Building - Unit 3.

1.

SUMMARY

DESCRIPTION

2. BACKGROUND/CIRCUMSTANCES

3. DETAILED DESCRIPTION OF PROPOSED CHANGES

4. TECHNICAL EVALUATION

5. REGULATORY EVALUATION

6. ENVIRONMENTAL CONSIDERATION

Evaluation of Proposed Changes License Amendment Request No. 2008-007 June 29, 2009 Page 2 1

SUMMARY

DESCRIPTION In accordance with 10CFR 50.90, Duke Energy Carolinas, LLC (Duke) proposes to amend Renewed Facility Operating License Number DPR-55. This License Amendment Request (LAR) will result in a complete revision of the Oconee Nuclear Site (ONS) Current Licensing Basis (CLB) with regard to High Energy Line Breaks (HELBs) events outside of the containment for Unit 3.

The LAR also includes several plant modifications and revisions to the Updated Final Safety Analysis Report (UFSAR) necessary to support the revised HELB Licensing Basis (LB) for Unit 3.

The Unit 3 changes proposed in this LAR include changes to the current HELB methodology and mitigation strategy as documented in ONDS-351, Rev. 2. This includes the results of the completed analysis for Unit 3 HELBs including the descriptions of the station modifications that have been or will be made as a result of this reanalysis. ONDS-351, Rev. 2 has been written with the HELB interaction analysis and pathway to a safe shutdown condition based upon the station configuration following the completion of these modifications.

ONDS-351, Revision 2 provides a complete re-evaluation of postulated HELBs and describes the 'as modified' station configuration for the newly identified HELBs on Unit 3.

This document, once fully implemented, will supersede in its entirety, the current HELB analysis provided in the original MDS OS-73.2 Report dated April 25, 1973, and its supplements dated June 22, 1973, and March 12, 1974, respectively, and establish a new licensing basis for future HELB considerations. Section 9 of Enclosure 2 identifies and describes the proposed modifications that have been or will be made in order to provide a pathway to a Safe Shutdown condition for postulated HELBs. Additional specific HELB mitigation strategies, regulatory commitments, and responses have been previously provided to the Staff in Duke's November 30, 2006, letter' (last revised on November 18, 20082), the Unit 1 HELB LAR submitted on June 26, 2008', and the Unit 2 HELB LAR submitted on December 22, 20084.

The analysis of effects resulting from postulated piping breaks outside of containment was Letter to Mr. James Dyer, Director, Office of Nuclear Reactor Regulation, from Henry B. Barron, Group Vice President and Chief Nuclear Officer, Nuclear Generation, Duke Energy Corporation, "Tornado/HELB Mitigation Strategies and Regulatory Commitments," dated November 30, 2006.

2 Letter to the U. S. Nuclear Regulatory Commission from Dave Baxter, Site Vice President, Oconee Nuclear Station, "Revision to Tomado/HELB Mitigation Strategies and Regulatory Commitments," dated November 18, 2008.

3 Letter to the U. S, Nuclear Regulatory Commission from Dave Baxter, Vice President, Oconee Nuclear Station, Duke Energy Corporation, "Proposed Licensing amendment Request to Revise the Oconee Nuclear Station current Licensing Basis for HELB Events outside of the Containment Buildings; Licensing amendment Request No. 2008-005," dated June 26, 2008.

4 Letter to the U. S, Nuclear Regulatory Commission from Dave Baxter, Vice President, Oconee Nuclear Station, Duke Energy Corporation, "Proposed Licensing amendment Request to Revise the Oconee Nuclear Station current Licensing Basis for HELB Events outside of the Containment Building - Unit 2; Licensing Amendment Request No. 2008-006," dated December 26, 2008.

Evaluation of Proposed Changes License Amendment Request No. 2008-007 June 29, 2009 Page 3 5

originally documented in Duke Power MDS Report No. OS-73.2 (including Supplements 16 and 27). Revision 2 of ONDS-351, "Analysis of Postulated High Energy Line Breaks (HELBs) Outside of Containment" contains the updated methodology and proposed strategies. As a result, the original HELB Report remains credited until the ONDS-351 report is fully completed includingthe incorporation of proposed modifications.

The enclosed HELB Report revision includes Safe Shutdown Analyses for HELBs postulated on the Unit 3 High Energy Lines. Those analyses credit normal plant equipment, the Standby Shutdown Facility (SSF), and the new Protected Service Water (PSW) System to achieve safe shutdown. The report also credits the use of the Main Steam Isolation Valves (MSIV), whenever a postulated HELB is determined to affect the Main Steam pressure boundary and the Safe Shutdown strategy relies on the SSF. The safety analysis, which describes the use of the MSIV/SSF for achieving and maintaining a Safe Shutdown condition and the description of the MSIVs is provided in Sections 7.0 and 3.0 of ONDS-351, Rev. 2, respectively.

2 BACKGROUND/CIRCUMSTANCES As ONS construction was nearing completion, the Atomic Energy Commission (AEC) issued a letter from A. Giambusso (AEC), Deputy Director for Reactor Projects Directorate of Licensinf, to Duke Power Company (now Duke Energy Carolinas, LLC), dated December 15, 1972 . The "Giambusso Letter" required licensees to address the consequences of pipe ruptures outside containment and submit their analyses to the AEC for review. Due to the specific guidance in the letter, the applicable events were identified as "High Energy Line Break" (HELB) events. The "Giambusso Letter" was amended by an errata sheet provided in a letter from A. Schwencer (AEC), Chief Pressurized Water Reactors Branch No. 4 Directorate of Licensing, to Duke Power Company, dated January 17, 19739 (the "Schwencer letter").

Duke's evaluations of postulated pipe ruptures outside containment were documented in MDS Report No. OS-73.2 dated April 25, 1973, with Supplement 1 to the report dated June 22, 1973 and Supplement 2 to the report dated March 12, 1974. The final report is referred to herein as "current HELB report," "MDS Report" and/or "OS-73.2."

The MDS report was incorporated into the ONS license application by reference. It was subsequently approved and accepted by the AEC. "Safety Evaluation prepared by the Directorate of Licensing related to the Oconee Nuclear Station, Units 2 and 3," (referred to 5 MDS Report No. OS-73.2, Analysis of Effects Resulting from Postulated Piping Breaks Outside Containment for Oconee Nuclear Station, Units 1, 2, & 3, prepared by Duke Power company, dated April 25, 1973.

6 MDS Report No. OS-73.2, Supplement 1, Analysis of Effects Resulting from Postulated Piping Breaks Outside Containment for Oconee Nuclear Station, Units 1, 2, & 3, prepared by Duke Power company, dated June 22, 1973.

7 MDS Report No. OS-73.2, Supplement 2, Analysis of Effects Resulting from Postulated Piping Breaks Outside Containment for Oconee Nuclear Station, Units 1, 2, & 3, prepared by Duke Power company, dated March 12, 1974.

8 Letter dated 15 December 1972 from A. Giambusso (AEC) to A. C. Thies (DPC) transmitting the "General Information Required for Consideration of the Effects of a Piping system Break Outside Containment."

9 Clarification Letter (related to the 15 December 1972 letter), dated 17 January 1973, from A. Schwencer (AEC) to A. C. Thies (DPC)

Evaluation of Proposed Changes License Amendment Request No. 2008-007 June 29, 2009 Page 4 herein as "the SER") dated July 6, 197310, was issued as part of the initial licensing of Units 2 and 3. SER Section 7.1.11 "High-energy Line Rupture External to the Reactor Building" addressed the MDS report, and Attachment E of the SER repeated the NRC HELB criteria, as amended by the Schwencer letter. The following is extracted from Section 7.1.11:

"The basic criteriarequire that:

(1) Protection be providedfor equipment necessary to shut down the reactor and maintain it in a safe shutdown condition, assuming a concurrentand unrelatedsingle active failure ofprotected equipment,from all effects resultingfrom ruptures in pipes carryinghigh-energyfluid, up to and including a double-ended rupture of such pipes, where the temperature andpressure conditions of the fluid exceed 200 'F and275 psig. Breaks should be assumed to occur in those locations specified in the '"pipe whip criteria." The rupture effects on equipment to be consideredinclude pipe whip, structural(includingthe effects ofjet impingement) and environmental.

(2) Protectionbe providedfor equipment necessary to shut down the reactorand maintain it in a safe shutdown condition, assuming a concurrentand unrelatedsingle activefailure ofprotected equipment,from the environmental and structuraleffects (including the effects ofjet impingement) resultingfrom a single open crack at the most adverse location in pipes carryinghigh-energyfluid routed in the vicinity of this equipment, where the temperature andpressure conditions of the fluid exceed 200 °F and 275 psig. The size of the cracks should be assumed to be 1/2 the pipe diameter in length and 1/2 the wall thickness in width....

Staff Evaluationand Conclusion The staff has evaluated the assessment performed by the applicantand has concluded that the applicanthas analyzed the facilities in a manner consistent with the intent of the criteriaand guidelinesprovided by the staff The staff agrees with the applicant's selection ofpipe failure locations and concludes that all requiredaccident situations have been addressedappropriatelyby the applicant.

Furthermorethe staff has evaluated the analyticalmethods and assumptions used in the applicant'sanalyses andfind them acceptable and concurs with the proposed plant modifications and the criteriato be used in their designs. "

Several years after approval of the MDS report and initial licensing of ONS, the SSF was built. The SSF provides additional defense-in-depth protection to achieve and maintain Mode 3 with an average Reactor Coolant System temperature > 525 'F following postulated fire, sabotage, or flooding events.

The SSF Reactor Coolant Make-up (RCMU) system is the SSF sub-system designed and credited to supply RC pump seal injection flow in the event that the High Pressure Injection (HPI), the normal make up system, becomes inoperable when a Unit's RCS temperature is >

10Safety Evaluation Report (From AEC) for Oconee Units 2 & 3, July 6, 1973.

Evaluation of Proposed Changes License Amendment Request No. 2008-007 June 29, 2009 Page 5 250 'F. It can recover RCS volume shrinkage caused by cooling the RCS to Mode 3 with an average Reactor Coolant temperature >_525 'F. However, the SSF Reactor Coolant Make-up System is not credited for events, such as LOCA, which result in significant loss of RCS inventory. The SSF Auxiliary Service Water System (ASW) is the SSF sub-system credited as the backup to the Feedwater (FDW) and Emergency Feedwater (EFW) systems.

A 1998 Duke HELB self-assessment revealed issues with the original OS-73.2 report, and as a result, Duke decided to fully revalidate and revise the HELB CLB. In late 1999, Duke initiated a project to determine scope of these CLB revision efforts1 1. This HELB CLB revision effort is being completed on a unit by unit basis with ONS Unit 1 (ONS-1) completed first and the remaining units thereafter.

3 DETAILED DESCRIPTION OF PROPOSED CHANGES Specifically, NRC approval is requested for: (1) the revised HELB LB and Revision 2 of ONDS-351 that provides the Unit 3 High Energy Line Interaction Analysis, (2) the associated Unit 3 station modifications to certain structures, systems, and components (SSCs) to better withstand the effects of postulated HELBs, and (3) the UFSAR revisions associated with including Unit 3 into the applicability of the revised HELB LB. The proposed Unit 3 modifications are described in section 9.0 of ONDS-351, Rev. 2.

4 TECHNICAL EVALUATION The information necessary for the technical evaluation is discussed in Revision 2 of ONDS-351. The following sections of ONDS-351 are submitted to address the Unit 3 postulated HELBs:

• Section 1.3.3 - Identification of Unit 3 specific calculations

• Section 2.0 - Identification of criteria for determining the high energy lines, break locations and types, and the evaluation criteria for shutdown sequences and interactions

• Section 3.3 - Description of MSIVs

• Section 6.1 - Identification of the high energy lines, high energy line boundaries, break locations, and break types for Unit 3

• Section 6.2 - Analysis of Unit 3 HELBs with Unit 3 SSCs

• Section 6.3 - Analysis of Unit 3 HELBs with Units 1 and 2 SSCs

• Section 7.0 - Analysis of Main Steam Line, Main Feedwater Line, and Letdown Line Breaks; inclusion of SSF/MSIV in Safe Shutdown scenarios

• Section 8.0 - Applicable regulatory criteria specific to Unit 3 Letter from W. R. McCollum, Jr., Vice President, Oconee Nuclear Station, to the Nuclear Regulatory Commission, "High-Energy Line Break outside Reactor Building Methodology," dated July 3, 2002.

Evaluation of Proposed Changes License Amendment Request No. 2008-007 June 29, 2009 Page 6 0 Section 9.0 - Identification of modifications to SSCs resulting from Unit 3 HELBs With the implementation of the methodology and associated modifications described in ONDS-35 1, Rev. 2, a pathway to achieving and maintaining a safe shutdown condition will exist for postulated Unit 3 HELBs. In addition, attainment of a cold shutdown condition will be possible for postulated Unit 3 HELBs although repairs may be necessary for some equipment.

5 TECHNICAL EVALUATION 5.1 SIGNIFICANT HAZARDS CONSIDERATION Duke has evaluated whether or not a significant hazards consideration is involved with the proposed amendment by focusing on the three standards set forth in 10 CFR 50.92, "Issuance of amendment," as discussed below:

1) Does the proposed amendment involve a significant increase in the probability or consequences of an accident previously evaluated?

Response: No.

Justification: The Unit 3 changes proposed in this LAR include revisions to the current HELB methodology and mitigation strategy as documented in a new HELB report. This report provides the completed analysis for ONS HELBs including the descriptions of the station modifications that have been or will be made as a result of this comprehensive HELB reanalysis.

The modifications associated with the revised HELB LB will be designed and installed in accordance with applicable quality standards such that the likelihood of failure of new or modified SSCs will not initiate failures, malfunctions, or inadvertent operations of existing accident mitigating SSCs, such as the KHUs, SSF, HPI, or the Central Tie Switchyard 100 kV alternate power systems. For Turbine Building HELBs that could adversely affect equipment needed to stabilize and cooldown the units, the addition of the PSW System provides added assurances that safe shutdown can be readily established and maintained beyond the 72-hour SSF mission time.

In conclusion, the changes will collectively enhance the station's overall design, safety, and risk margin; therefore, the proposed change does not involve a significant increase in the probability or consequence of an accident previously evaluated.

2) Does the proposed amendment create the possibility of a new or different kind of accident from any accident previously evaluated?

Response: No.

Justification: The proposed modifications address potential adverse consequences from a HELB outside of containment. These modifications will be designed and

Evaluation of Proposed Changes License Amendment Request No. 2008-007 June 29, 2009 Page 7 installed in compliance with applicable quality standards such that there are reasonable assurances that they will neither introduce nor cause new failure mechanisms, malfunctions or accident initiators not already considered in the current HELB design and licensing basis.

The overall effect of the changes to the HELB LB is considered an enhancement to the station's ability to achieve safe and cold shut down following a damaging HELB; therefore, the proposed change does not create the possibility of a new or different kind of accident from any accident previously evaluated.

3) Does the proposed amendment involve a significant reduction in a margin of safety?

Response: No.

Justification: The revised HELB LB will collectively enhance the station's overall design, safety, risk margin, and the station's ability to mitigate a HELB event; therefore, the proposed change does not involve a significant reduction in a margin of safety.

Based on the above, Duke concludes that the proposed amendment does not involve a significant hazards consideration under the standards set forth in 10 CFR 50.92(c),

and, accordingly, a finding of "no significance hazards consideration" is justified.

5.2 APPLICABLE REGULATORY REQUIREMENTS/CRITERIA 5.2.1 UFSAR 10.4.7.3.2 (EFW Response Following a HELB) describes the mitigation strategies for HELBs resulting in a loss of TC, TD, and TE switchgear, Feedwater/Main Steam line breaks causing loss of SG pressure boundary, and other Condensate/Feedwater line breaks that result in a loss of condenser hotwell inventory.

5.2.2 UFSAR 3.6.1 (Postulated Piping Failures in Fluid Systems Inside and Outside Containment), denotes that the analysis of effects resulting from postulated piping breaks outside containment is contained in Duke Power MDS Report No.

OS-73.2, dated April 25, 1973, including revision through Supplement 2.

Additionally stated is that an evaluation of potential non-safety grade control system interactions during design basis high energy line break accidents is contained in the Duke Power/Babcock and Wilcox Report dated October 5, 1979.

5.3 PRECEDENT HELB methodology-related license amendment requests have been previously submitted and approved by the Staff for the D. C. Cook, Clinton, Crystal River-3, Comanche Peak, South Texas Project, and Oconee Nuclear Stations.

Evaluation of Proposed Changes License Amendment Request No. 2008-007 June 29, 2009 Page 8

5.4 CONCLUSION

In conclusion, based on the considerations discussed above, (1) there is reasonable assurance that the health and safety of the public will not be endangered by operation in the proposed manner, (2) such activities will be conducted in compliance with the Commission's regulations, and (3) the issuance of the amendment will not be inimical to the common defense and security or to the health and safety of the public.

6 ENVIRONMENTAL CONSIDERATION Duke has evaluated this license amendment request against the criteria for identification of licensing and regulatory actions requiring environmental assessment in accordance with 10CFR 51.21. Duke has determined that this license amendment request meets the criteria for a categorical exclusion as set forth in 10CFR 51.22(c) (9). This determination is based on the fact that this change is being proposed as an amendment to a license issued pursuant to 10CFR 50 that changes a requirement with respect to installation or use of a facility component located within the restricted area, as defined in 10CFR 20, or that changes an inspection or a surveillance requirement, and the amendment meets the following specific criteria:

(i) The amendment involves no significant hazards consideration.

As demonstrated in Section 5.1, this proposed amendment does not involve a significant hazards consideration.

(ii) There is no significant change in the types or significant increase in the amounts of any effluent that may be released offsite.

The ONS design requirement is that systems, structures, or components (SSCs) required for shutting down and maintaining the units in a shutdown condition will not fail as a result of damage caused by a HELB outside of containment. The change proposed in this amendment request will enhance and clarify the overall HELB LB to better ensure that this design requirement is maintained. Since the principal barriers to the release of radioactive materials are not modified or affected by this change, no significant increases in the amounts of any effluent that could be released offsite will occur as a result of this proposed change.

(iii) There is no significant increase in individual or cumulative occupational radiation exposure.

Because the principal barriers to the release of radioactive materials are not modified or affected by this change, there will be no significant increase in individual or cumulative occupational radiation exposure resulting from this change.

ENCLOSURE 2 ONDS-351, "ANALYSIS OF POSTULATED HIGH ENERGY LINE BREAKS (HELBS)

OUTSIDE OF CONTAINMENT" (REVISION 2)

I /