ML080390239

From kanterella
Jump to navigation Jump to search
Revision to Tornado/Helb Mitigation Strategies and Regulatory Commitments
ML080390239
Person / Time
Site: Oconee  Duke Energy icon.png
Issue date: 01/25/2008
From: Barron H
Duke Energy Carolinas, Duke Power Co
To:
Document Control Desk, Office of Nuclear Reactor Regulation
References
Download: ML080390239 (18)
v • d • e


Text

Duke Group HENRY Executive B. BARRONand Energy Chief Nuclear Officer Duke Energy Corporation 526 South Church St.

Charlotte, NC 28202 Mailing Address:

EC-O3XM / PO Box 1006 Charlotte, NC 28201-1006 704 382 2200 January 25, 2008 704 382 6056 fax hbarron@duke-energy.corn Document Control Desk U.S.- Nuclear Regulatory Commission Washington, DC 20555-0001

Subject:

Duke Power Company LLC d/b/a Duke Energy Carolinas, LLC (Duke)

Oconee Nuclear Station, Units 1, 2, and. 3-.

Docket Numbers 50-269, 50-270, and 50-287, Renewed Operating Licenses DPR-38, DPR-47, and DPR-55 Revision to Tornado/HELB Mitigation Strategies and Regulatory Commitments

References:

1. Letter to the Nuclear Regulatory Commission from Henry B.

Barron (Duke) dated November 30, 2006, "Tornado/HELB Mitigation Strategies and Regulatory Commitments"

2. Letter to the Nuclear Regulatory Commission from Bruce H. Hamilton (Duke) dated June 28, 2007, "Revision to Tornado/HELB Mitigation Strategies and. Regulatory Commitments" The purpose of this letter is to notify the Nuclear Regulatory Commission (NRC) of revisions to the commitments provided in Reference 1 in accordance with the provisions of Commitments 1OT and 25H. Adjustments to two of the commitments in Reference 1 were previously provided to the NRC in Reference
2. The list of commitments in Reference 1, including the revisions discussed herein, is provided in Attachments 1 and 2.

The revised commitments and the reasons for the revisions are provided below.

1) Commitments 5T, 14T and 4T The due date for Commitment 5T has been revised to reflect the impact of the delay in approval of the LAR submitted in Commitment 6T and the reduction in scope of the application of Fiber Reinforced Polymer (FRP) approved by that LAR (Cask Decontamination Tank Room only). A new Commitment 14T has been added involving the submittal of an additional License Amendment Request (LAR) for application of FRP in strengthening the West Penetration Room (WPR) brick walls against the effects of tornado differential pressure.

The suitability and design of FRP to strengthen brick walls like those of the WPR for tornado differential pressure loading will be based upon testing.

www. duke-energy. corn

Nuclear Regulatory Commission Revisions to Tornado/HELB Mitigation Strategies and Regulatory Commitments January 25, 2008 Page 2 Duke is providing the above information as committed to in Reference 2.

Commitment 5T has also been revised to reflect the use of Regulatory Guide 1.76, Rev. 1.

The due date for Commitment 4T was revised to reflect the impact of the delay in approval of the LAR submitted in Commitment 6T. Improving the protection of the Borated Water Storage Tank and associated piping and the WPR and CDTR walls are interrelated activities that must be properly sequenced in design and construction. Delays in completing the TORMIS analysis, as discussed relative to Commitment 7T, have also impacted the ability to meet the commitment completion dates for Commitment 4T and 3T.

In summary, delay in approval of the FRP LAR and the necessity of conducting additional FRP testing on brick walls for further application of the technology have resulted in a revision to these commitment completion dates.

The design and implementation schedule remains challenging.

2) Commitment 7T The due date for Commitment 7T has been revised due to delays in completing the TORMIS analysis. Duke will not be able to meet the Standard Review Plan TORMIS acceptance criteria for the Oconee Nuclear Station without providing additional modifications beyond those already proposed to the NRC. Analysis to evaluate the feasibility and scoping of those modifications and the impact on TORMIS results has resulted in the date for the LAR submittal being revised. Additional modifications resulting from the TORMIS analysis have impacted Commitment 4T, as discussed previously.

The commitment requirement to include changes to the Selected Licensee Requirements (SLCs) as part of the LAR was removed since this action will be addressed in a subsequent High Energy Line Break LAR submittal.

3) Commitments 11T, 12T and 13T These are additional commitments to reflect the decision by Duke to provide Main Steam Isolation Valves (MSIV) in the Main Steam header just outside of the Turbine Building. These valves will provide a stable platform for operation of the Standby Shutdown Facility and planned Protected Service Water (PSW) system; obviate the need to use equipment in the Turbine Building to achieve safe shutdown; provide an assured means of Main Steam pressure boundary control following damage in the Turbine Building; and facilitate repair of plant equipment following damage in the Turbine Building. These modifications will require a LAR whose submittal date has not been determined. Duke is continuing to proceed, consistent with its corporate governance requirements, to obtain necessary internal approvals to fund the implementation of these commitments.
4) Commitments 2H, 4H, 6H, 8H These commitments have been revised to delete certain inspections that are no longer appropriate in lieu of the planned installation of MSIVs. In addition,

Nuclear Regulatory Commission Revisions to Tornado/HELB Mitigation Strategies and Regulatory Commitments January 25, 2008 Page 3 the completion dates have been changed to align with the revised completion dates for commitments 22H, 23H, and 24H.

5) Commitments 22H, 23H, 24H The due dates for these commitments have been extended 3-months. The required analyses have taken longer to complete than scheduled because additional analyses were required to support the feasibility and impact of the planned installation of the MSIVs. In addition, based on the recently-completed internal review of the tornado LAR and the occurrence of a spring 2008 outage, an increased review time is expected for the HELB LAR.

Commitments also have been revised to delete certain inspections that are no longer appropriate in lieu of the planned installation of MSIVs and to provide additional clarification.

6) Commitments 25H and 1OT The dates for these commitments were extended based on the addition of the MSIV modification commitments.

Other than the revisions to the Commitments in Reference 1 discussed in this letter, the remaining commitments are being completed on schedule and progress is such that future commitment completion dates, such as for installation of PSW, remain as scheduled. Duke believes that revisions to the LAR submittal dates discussed in this letter should not impact the overall resolution schedule for these issues.

Inquiries concerning this matter should be directed to Mr. Richard Freudenberger, Manager, Oconee Safety Assurance, at (864) 885-3163.

Very sincerely yours, Henry B. Barron Group Vice President and Chief Nuclear Officer Nuclear Generation Attachments

Nuclear Regulatory Commission Revisions to Tornado/HELB Mitigation Strategies and Regulatory Commitments January 25, 2008 Page 4 cc:

Mr. James Dyer Director, Nuclear Reactor Regulation U.S. Nuclear Regulatory Commission 11555 Rockville Pike Rockville, Maryland 20852-2738 Mr. Victor M. McCree Acting 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. Leonard N. Olshan Senior Project Manager Office of Nuclear Reactor Regulation U.S. Nuclear Regulatory Commission Mail Stop 0-8 G9A 11555 Rockville Pike Rockville, Maryland 20852-2738 Mr. Timothy McGinty Deputy Director Division of Operator Reactor Licensing Office of Nuclear Reactor Regulation U.S. Nuclear Regulatory Commission 11555 Rockville Pike Rockville, Maryland 20852-2738 Mr. Charles Casto 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. Joseph W. Shea 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 Revisions to Tornado/HELB Mitigation Strategies and Regulatory Commitments January 25, 2008 Page 5 Mr. James Moorman 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. Robert E. Carroll U.S. Nuclear Regulatory Commission - Region II Sam Nunn Atlanta Federal Center, 23 T85 61 Forsyth St., SW Atlanta, GA 30303-8931 Mr. Dan Rich NRC Senior Resident Inspector 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 Revisions to Tornado/HELB Mitigation Strategies and Regulatory Commitments January 25, 2008 / Page 6 bcc:

D. A. Baxter R. A. Jones R. Mike Glover B. G. Davenport J. R. Sumpter T. D. Brown L. M. Kanipe S. L. Nader L. F. Vaughn S. L. Batson J. E. Burchfield R. J. Freudenberger G. K. Mc Aninch J. E. Smith (NRC Commitment Coordinator)

S. C. Newman J. N. Robertson R. E. Hall T. D. Mills R. L. Gill - NRI&IA R. D. Hart - CNS K. L. Ashe - MNS D. Repka NSRB, EC05N ELL, ECO50 File - T.S. Working ONS Document Management

Attachment 1 Tornado Commitments No. Commitment Completion Date 1T Physically protect the Unit 3 Control Room north wall from 12-2008 the effects of a tornado per associated UFSAR Class 1 structure tornado wind, differential pressure, and missile criteria.

2T Physically protect the Standby Shutdown Facility (SSF) Complete diesel fuel vents from the effects of a tornado per associated UFSAR SSF tornado wind, differential pressure and missile criteria.

3T Analyze and/or protect as required, the elevated/exposed 12-2007 portions (at the north end of the Standby Shutdown Facility 6-2008 (SSF) and where the SSF and CT-5 trenches intersect) of the SSF cable/pipe trench from the effects of a tornado per (The trench associated UFSAR SSF tornado wind, differential pressure intersection and missile criteria, modification was completed on the original 12-2007 schedule.

The north end of the SSF will be addressed by TORMIS per the above revised date.)

4T Analyze and protect as required, each unit's Borated 1-2-2009 Water Storage Tank and associated piping per the UFSAR 12-2010 Class 1 structure tornado wind, differential pressure, and missile criteria.

5T Improve the protection of tornado mitigation equipment 112-2009 located within the West Penetration Room (WPR) and 12-2010 Cask Decontamination Tank Room (CDTR) from the effects of a tornado. The CDTR block walls will be upgraded to UFSAR Class 1 structuro Regulatory Guide 1.76, Rev. 1 tornado differential pressure criteria using Fiber Reinforced Polymer. (Loads generated by the design tornado wind will be resisted by external siding and transferred directly into the reinforced concrete ,frame of

Page 2 No. Commitment Completion Date the Auxiliary Building via structural steel members.) Duke will evaluate the need for additional missile protection of the CDTR/WPR walls using TORMIS.

6T Submit a License Amendment Request (LAR) to use Fiber Complete Reinforced Polymer (FRP) technology for application in Submitted strengthening selected masonry walls against the effects 6/1/2006 of tornado wind and differential pressure. The LAR will commit to utilizing technical procedures to control testing of concrete substrate and installation and inspection of the FRP systems and in-service inspection of the FRP system once installed.

7T Submit a License Amendment Request (LAR) establishing  !-2008 a new tornado licensing basis (LB) and mitigation strategy. 6-2008 The LAR will address the two redundant mitigation systems, Standby Shutdown Facility (SSF) and Protected Service Water/High Pressure Injection (PSW/HPI) used in the tornado mitigation strategy.

The LAR will commit to the following and include information concerning:

0 Basic elements of the Selecte-d Lic-MSensee Comm~itmnents changes to ensure licensing basis, clarity and systemns structures and comnponent (SSC) operabilfity such that tornadeo mitigatiGn* apabilty is

Seal Injection or Reactor Coolant System (RCS) pressure boundary functions in the first 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> after the event that are not currently protected in accordance with UFSAR tornado missile criteria.

The elimination of credit for the Spent Fuel Pool to High Pressure Injection (HPI) pump flow path.

In accordance with the CLB, single active failures will

Page 3 No. Commitment Completion Date not be assumed in the updated tornado mitigation strategy.

  • A description of the upgrade of the current low pressure Auxiliary Service Water (ASW) system to a high head PSW system that can be actuated, aligned, and controlled from the main Control Rooms (CR) for SSDHR. This system will be credited for both tornado and HELB events.

" The ASW upgrade also includes the installation of new PSW switchgear with alternate power provided from the KHUs via a tornado protected, underground feeder path. The PSW switchgear and supporting equipment will be located in a new tornado protected building. Power will also be provided from the Central/Lee 100kV transmission line through a new transformer that will be located to further minimize concurrent damage of the station switchyard, KHU and the new transformer.

Specifically, the modification will provide alternate power for:

1. The PSW/HPI system itself,
2. An HPI pump for RCP seal injection that can be promptly aligned from the main CRs,
3. A sufficient number of pressurizer (PZR).heaters (also operated from the main CRs) to maintain a steam bubble in the PZR for RCS pressure control,
4. The existing vital instrumentation and control battery chargers,
5. The SSF SSCs in case the SSF diesel generator is unavailable,
6. RCS High Point Vent and Reactor Vessel Head Vent valves for boration and RCS inventory control. At least one high point vent is required to control RCS inventory at Safe Shutdown conditions.

8T Installation of the PSW/HPI modifications. 12-2010

Page 4 No. Commitment Completion Date 9T A program will be developed to monitor site missile Complete inventories.

1OT Verbally notify in advance the Deputy Director, Division of As necessary, Reactor Licensing of the NRC, followed by a written until 12-2012 communication, of significant changes in the scope and/or 12-2014 completion dates of the commitments in Attachment 1 of this submittal. The notification will include the reason for the changes and the modified commitments and/or schedule.

11T Installation of Main Steam Isolation Valve modifications. Unit 1 2012 12T Unit 2 2014 13T Unit 3 2013 14T Submit a License Amendment Request (LAR) to use Fiber 12-2008 Reinforced Polymer (FRP) technology for application in strengthening the West Penetration Room (WPR) brick walls against the effects of tornado differential pressure using Regulatory Guide 1.76, Rev. 1 criteria. (Loads generated by the design tornado wind will be resisted by external siding and transferred directly into the reinforced concrete frame of the Auxiliary Building via structural steel members.) The LAR will commit to utilizing technical procedures to control testing of concrete substrate and installation and inspection of the FRP systems and in-service inspection of the FRP system once installed. The suitability and design of FRP to strengthen brick walls like those of the WPR for tornado differential pressure loading will be based upon testing.

Attachment 2 High Energy Line Break Commitments No. Commitment Completion Date HELB Piping Inspection Program 1H Implement an inspection program that ensures the Complete Auxiliary Building Main Steam and Main Feedwater girth and accessible attachment welds are re-inspected at least once during each subsequent 10 year ASME Section XI In-service Inspection interval for weld flaws and thickness.

2H Implement an inspection program that ensures the Unit 1,03 2008 following welds are re-inspected at least once during each 06-2008 subsequent 10 year ASME Section XI In-service Unit 2, 09-2008 Inspection interval for weld flaws and thickness: 12-2008

a. Other Auxiliary Building high energy piping critical Unit 3, 03-2009 crack locations at welds. 06-2009
b. S..oct.d Tubino Bu.ilding high energy piping gi01h (Changes wneeded to align G. Seo!ct-d Turbino Building high ,nor piping with 22H, 23H, critical crack Ilocatios at welds. and 24H) 3H Complete initial ASME Section XI In-service Inspection 07-2008 interval ultrasonic testing of the Auxiliary Building Main Steam and Main Feedwater girth welds and accessible attachment welds for weld flaws and thickness.

Accessible attachment welds are to undergo visual examination for general weld quality as well as surface examination using either a magnetic particle or a liquid penetrant test.

4H Complete initial ASME Section XI In-service Inspection 03-2012 interval ultrasonic testing of the following welds for weld flaws and thickness. Accessible attachment welds are to undergo visual examination for general weld quality as well as surface examination using either a magnetic particle or a liquid penetrant test:

a. Other Auxiliary Building high energy piping critical crack locations at welds.
b. S9loctodturbiwne bu ildinghighonorgypipnngogirth4 ___-_

Page 2 No. Commitment Completion Date welde7 G. Selectod Turbino Building high enorgy piping critia crack locati**r, at wolds 5H Implement an inspection program that ensures that Complete accessible piping base metal downstream of Main Feedwater isolation valves located in the East Penetration Room and not enclosed by the guard pipe receive an ASME Section XI In-service Inspection interval ultrasonic testing inspection at least once every 10 years.

6H Implement an inspection program that ensures the Unit 1,03 -2008 following piping base metal receive an ASME Section XI 06-2008 In-service Inspection interval ultrasonic testing inspection Unit 2, 09 -2008 at least once every 10 years. 12-2008

a. Other Auxiliary Building high energy piping critical Unit 3, 03-2009 crack locations not at welds. 06-2009
b. S...oc.t.d Tu.bino Building high nerg pipin (Changes critical crack locGation not at weld!, needed to align with 22H, 23H, and 24H) 7H Complete the initial ASME Section XI In-service Inspection Complete interval ultrasonic testing inspection of piping base metal downstream of Main Feedwater isolation valves located in the East Penetration Room and not enclosed by the guard pipe.

8H Complete initial ASME Section XI In-service Inspection 03-2012 interval ultrasonic testing inspection of the following piping base metal:

a. Other Auxiliary Building high energy piping critical crack locations not at welds.
b. Solorct*d Turbino Building high onorgy piping critiGal crGck locations not at welds.

9H Implement an inspection program that requires external Complete visual inspection of accessible attachment welds at the terminal ends inside the main feedwater guard pipe at least once every 10 years.

Page 3 No. Commitment Completion Date 10H Complete initial visual inspections of accessible Complete attachment welds at the terminal ends inside the main feedwater guard pipes.

Repair of Electrical Penetration Enclosures Located in the EPR to the Correct Configuration 11 H Inspect and repair the Unit 2 East Penetration Room Complete electrical penetration termination enclosures to their correct configuration. Missing and/or damaged covers, gaskets, and fasteners will be repaired or replaced.

12H Inspect and repair the Unit 1 East Penetration Room Complete electrical penetration termination enclosures to their correct configuration. Missing and/or damaged covers, gaskets, and fasteners will be repaired or replaced.

13H Inspect and repair the Unit 3 East Penetration Room Complete electrical penetration termination enclosures to their correct configuration. Missing and/or damaged covers, gaskets, and fasteners will be repaired or replaced.

14H Create an inspection plan to select a portion of Units 1, 2 Complete and 3 enclosures to open and inspect for signs of internal debris and corrosion.

15H Revise station procedures and processes as needed to Complete ensure penetration termination enclosures are maintained in their correct configurations.

EPR Flood Prevention Modifications 16H Complete the design and installation of flood outlet Complete devices for the Unit 1 East Penetration Room.

17H Complete the design and installation of flood outlet Complete devices for the Unit 2 East Penetration Room.

18H Complete the design and installation of flood outlet Complete devices for the Unit 3 East Penetration Room.

19H Complete the design and installation of flood Complete impoundment and exterior door flood improvement features for the Unit 1 East Penetration Room

Page 4 No. Commitment Completion Date 20H Complete the design and installation of flood Complete impoundment and exterior door flood improvement features for the Unit 2 East Penetration Room.

21 H Complete the design and installation of flood Complete impoundment and exterior door flood improvement features for the Unit 3 East Penetration Room.

HELB Design and Licensing Basis Reconstitution 22H Submit License Amendment Requests (LARs) to Unit 1, 03-2008 23H establish an updated HELB Licensing Basis and HELB 06-2008 mitigation strategy for Oconee Nuclear Station (ONS).

24H Unit 2, 09-2008 The LARs will address deviations from and 12-2008 clarifications of selected portions of References 6 (the Giambusso letter) and 7 (the Schwencer letter) and the Unit 3, 08-20.,

criteria that will be substituted or clarified. Each unit 06-2009 LAR will include licensing basis changes based on design basis documents replacing OS 73.2.

The first LAR will commit to the following and will also provide the analysis results for Unit 1.

  • The LAR will outline the basic elements of Selected Licensee Commitment changes to ensure licensing basis clarity and component operability such that HELB mitigation capability is maintained.
  • The LAR will identify any Turbine Building (TB) high energy piping girth welds and critical crack locations at welds whose failure would result in adverse interactions impacting the ability to achieve safe shutdown (SSD) or cold shutdown (CSD), as appropriate, following a HELB event. These-,A'el aro roferorncd in G*mFmitmront #'s 22HII and 4H as IC ^11[r('^uriruI ozI%]I t"!iri ' ^r' VI

.. ..+ ... OLrh

........ ... ~ ...... ~ ,-

..... . .. ... . .... d ..... -* ---

  • L VI IIIV*I VI *Vi1 IVV*LIVI IV welds", rospoctively.

The LAR will identify any TB high energy critical crack locations not at welds whose failure would result in adverse interactions impacting the ability to achieve SSD or CSD, as appropriate, following a HELB event. Thoes welds aro rofoencod inR F

I_____men fAIIIILIUI sT efl and 819 as seUIUUWU +n [I~

tigt _______

Page 5 No. Commitment Completion Date onregy critical crack locations not At Wois".

" The LAR will identify any crack locations in high energy piping other than Main Steam and Main Feedwater in the Auxiliary Building (AB) per the criteria in Commitments 22H-24H. These locations are referenced in Commitment #Ws2H, 4H, 6H and 8H as "other AB high energy piping critical crack locations".

" High energy systems will be defined as those systems with operating temperatures greater than or equal to 200 F or pressures greater than eo equal-te 275 psig. For those systems that operate at high energy conditions less than 1% of the total plant operating time or at high energy conditions less than 2% of the total system operating time, no breaks or cracks will be postulated.

  • For piping that is seismically analyzed, i.e. stress analysis information is available and the analysis includes seismic loading, intermediate breaks will be postulated in equivalent Class 2 or 3 piping at axial locations where the calculated stress for the applicable load cases exceed 0. 8 (SA + Sh).

Applicable load cases include internal pressure, dead weight (gravity), thermal, and seismic (defined as operational basis earthquake, OBE).

Intermediate breaks will not be postulated at locations where the expansion stress exceeds

0. 8 SA. Thermal stress is a secondary stress, and taken in absence of other stresses, does not cause ruptures in pipe. This approach is permitted by GL 87-11 as a deviation from Reference 6.

" For piping that is not rigorously analyzed or does not include seismic loadings, intermediate breaks will be postulated at locations as provided in BTP MEB 3-1 (Section B.1.c(2)(b)(i)). This MEB 3-1 section provides more detail than the associated requirements in Reference 6, as amended by Reference 7, so that the most adverse locations can be identified as required in these references.

  • Terminal ends are vessel/pump nozzles, building penetrations, in-line anchors, and branch to run

Page 6 No. Commitment Completion Date connections that act as essentially rigid constraints to piping thermal expansion. A branch appropriately modeled in a rigorous stress analysis with the run flexibility and applied branch line movements included and where the branch connection stress is accurately known will use the stress criteria noted above for postulating break locations as noted above in the 6 th bullet. For, unanalyzed branch connections or where the stress at the branch connection is not accurately known, break locations will be postulated as noted in the 7 th bullet above.

  • Reference 6, as amended by Reference 7, provided criteria to determine pipe break orientation at break locations and specifies that longitudinal breaks in piping runs and branch runs be postulated for nominal pipe sizes greater than or equal to four inches. Circumferential breaks are to be postulated at the terminal ends. The design of existing and potentially new rupture restraints may be used to mitigate the results from such breaks, including prevention of pipe whip and alteration of the break flow. For ONS, longitudinal breaks will not be postulated at terminal ends.
  • For piping that is seismically analyzed (i.e. stress analysis information is available and the analysis includes seismic loading), critical cracks will be postulated in equivalent Class 2 or 3 piping at axial locations where the calculated stress for the applicable load cases exceed O.4 (SA + Sh).

Applicable load cases will include internal pressure, dead weight (gravity), thermal and seismic (defined as operational basis earthquake, OBE). This approach is in accordance with BTP MEB 3-1 (Section B.1 .e(2)) which is deviation from the requirements of Reference 7.

  • For piping that is not rigorously analyzed or does-not include seismic loadings, critical cracks will not be postulated since the effects of postulated circumferential and longitudinal breaks at these locations will bound the effects from critical cracks (See the 7 th bullet above).

Page 7 No. Commitment Completion Date

" Actual stresses used for comparison to the break and crack thresholds noted above will be calculated in accordance with the ONS piping code of record, USAS B31.1.0. (1967 Edition) Allowable stress values SA and Sh will be determined in accordance with the USAS B31.1.0 or the USAS B31.7 (February 1968 draft edition with errata) code as appropriate.

  • Moderate energy line breaks will not be postulated.

Moderate energy rules were not in place when ONS was licensed and built and the effect of moderate energy cracks have not been evaluated.

" Systems and components not required to reach SSD, but necessary to reach CSD, will not be protected from HELBs. Station repair guidelines will be employed to effect repairs as required to those systems and components necessary to reach CSD. The affected unit will remain at SSD conditions while those necessary repairs are completed. Current damage repair guidelines and procedures will be enhanced, as necessary, to extend SSD capability beyond the 72-hour Current Licensing Basis (CLB) and to establish CSD. The enhanced capability will not be part of the CLB or related to operability of the Standby Shutdown Facility (SSF).

" A single active failure will be postulated in the Protected Service Water/High Pressure Injection (PSW/HPI) or SSF systems for the initial event mitigation as well as achieving and maintaining SSD. Single active failures will not be postulated during plant cooldown to CSD. The LAR will include a provision to continue reliance on the CLB regarding application of the single failure criteria to the letdown piping.

  • Onsite emergency power distribution systems located in the TB will not be credited for mitigation of HELBs that could occur in the TB. New switchgear, to be installed as part of the PSW system, along with the SSF will be utilized for mitigation of HELBs that could occur in the TB.

______ 4 J

Page 8 No. Commitment Completion Date

" The new PSW and the East Penetration Room flood prevention modifications will be designed and constructed to the quality standards applicable to a safety-related system.

  • A new time critical action will be created for the operators to place the PSW system into operation within 15 minutes following a complete loss of main and emergency feedwater with a complete loss of 4160 VAC power. A single HPI pump can be aligned to the Borated Water Storage Tank and started to reestablish seal cooling for the reactor coolant pumps. A new time critical action will be created for the operators to place HPI into operation (from PSW power) within 20 minutes following a complete loss of 4160 VAC power. The new time critical actions will be time validated in accordance with the current ONS standards for emergency procedures. The operator would then maintain SSD conditions and energize pressurizer heaters as necessary to maintain reactor coolant pressure within limits.
  • An analysis that shows that SSD can be maintained with a failed open MSIV.

25H Verbally notify in advance the Deputy Director, Division of As necessary, Reactor Licensing of the NRC, followed by a written until 03-2012 communication, of significant changes in the scope and/or 03-2014 completion dates of the commitments in Attachment 3 to this submittal. The notification will include the reason for the changes and the modified commitments and/or schedule.

Retrieved from "https://kanterella.com/w/index.php?title=ML080390239&oldid=2571801"