ML20133D219
| ML20133D219 | |
| Person / Time | |
|---|---|
| Site: | McGuire, Mcguire  |
| Issue date: | 10/02/1985 |
| From: | Tucker H DUKE POWER CO. |
| To: | Adensam E, Harold Denton Office of Nuclear Reactor Regulation |
| Shared Package | |
| ML20133D223 | List: |
| References | |
| NUDOCS 8510080359 | |
| Download: ML20133D219 (9) | |
Text
e Duxis Powicit Godriwxy I'.O. ISO x 331f10 CII AHLOrTi!, N.C. 2f1242 HAL11.TICHEH TE LE PIIONE (704) ora-4 sat
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October 2, 1985 Mr. Ilarold R. Denton, Director Office of Nuclear Reactor Regulation U. S. Nucicar Regulatory Commission Washington, D. C. 20555 Attention:
Ms. E. G. Adensam, Chief Licensing Branch No. 4
Subject:
McGuire Nucicar Station Docket Nos. 50-369 and 50-370
Dear Mr. Denton:
By letter dated May 9,1985 Duke submitted for NRC review and approval a proposed license amendment and Techncial Specification revision in support of deletion of the Upper llead Injection (Ulli) system at McGuire. That submittal committed to provide the results of confirmatory studies outlined therein.
Accordingly, please find attached a document entitled "McGuire Nucicar Station, Safety Analysis for Ulli Elimination" dated September 1985.
The results of this study demonstrate that existing Technical Specifications not revised per the May 9, 1985 submittal remain conservative for operation without Ulli while all safety and regulatory requirements remain satisfied.
in addition, several input assumptions to the analyses peaking factor (F ECCS accumulator boron concentration, and initini containment ice weight q),were revised. The results demonstrate that not only are the existing values of these items in Techncial Specifications conservative, but also that they may be relaxed.
It is Duke's intention to propose changes to Techncini Specifications by separate licensing actions following NRC approval of deletion of Ulli.
This document supplements the proposed Techncini Specification revisions l
contained in our 1ctter dated May 9, 1985. As such no additional fees are required.
0510000359 051002 i
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Mr. liarold R. Denton, Director October 2, 1985 Page 2 Following preliminary NRC review of this study, Duke requests a meeting during the week of October 14, 1985, with the staff to answer any initial questions regarding the results and to facilitate timely approval.
It is Duke's desire to obtain approval of this amendment at the earliest possible date and no later than February 1, 1986 to allow efficient management of resources planned for the McGuire Unit I refueling outage, currently estimated to start April 1986 (100% capacity f actor).
Very truly yours, l
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llal B. Tucker RI.G/hrp Attachment ec:
Dr. J. Nelson Grace, Regional Administrator U. S. Nuclear Regulatory Commission Reglon 11 101 Marietta Street, NW, Suite 2900 Atlanta, Georgia 30323 Mr. W. T. Orders NRC Resident inspector McGuire Nuclear Station Mr. Dart llood Project Manager Division of I.icensing office of Nuclear Regulatory Commluston Washington, D. C. 20555
I APPENDIX A LARGE & SMALL BREAK LOCA r
i 8992Q 10/082185
1.0 INTRODUCTION
Upper Head Injection (UHI) was installed at McGuire Units 1 and 2 in order to provide enhanced large break LOCA ECCS performance as calculated using 10 CFR 50 Appendix K models and' thereby ease normal plant operating restrictions which resulted from the conservative analytical approach. The development of improved analytical models combined with numerous operational and design problems related to the UHI System led to the investigation of the possible deletion of UHI from McGuire.
A scoping study was performed by Westinghouse to demonstrate that safety and regulatory requirements could continue to be satisfied and that acceptable operating limits could be established in the absence of the UH1 System.
Based upon the preliminary results, the decision was made to proceed with the UHI removal project.
The Technical Specification changes to delete the requirements for UHI were addressed via a two phase process.
The first phase included the scoping study, preliminary discussions with NRC, and the identification and submittal of the Technical Specification revisions associated with the actual hardware changes that will be made once the deletion of the requirement for UHI is approved.
The second phase of the process includes performing confirinatory studies to demonstrate that existing Technical Specifications not revised per the Phase I submittal remain conservative for operation without UHI while all safety and regulatory requirements remain satisfied.
The results of the i
confirmatory analyses are presented in the remainder of this report and associated appendices.
During the performance of these confirmatory analyses, several input parameters not related to the UH1 System were also revised.
Existing Technical Specifications are conservative with respect to these parameters and revision of the limits on core peaking factor (F ), and ECCS g
accumulator and RWST boron concentration will be requested via a separate submittal.
The Phase 11 analyses include licensing basis transient analysis of a spectrum of large and small break loss of coolant accidents (LOCA), the steamline break accident, and containment response to LOCA and steamline break transients.
in order to expedite the review process and allow an casier comparison of existing analyses to the UH1 removal confirmatory analyses, the details of the analytical results are provided in the form of markups of the applicable FSAR section.
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2.0 ECCS ANALYSIS Upper Head Injection (UHI) was installed at McGuire Units 1 and 2 to increase operational flexibility through a higher total core peaking factor.
The pumped safety injection / cold leg accumulator capability of McGuire was not decreased when UHI was added.
Rather, McGuire without UH1 has the same installed ECCS capability as the standard RESAR-35 4-loop Westinghouse plant.
Advances in ECCS technology and experimental information gathered over the past decade permit more accurate but still conservative Appendix K ECCS computations to be performed. Use of this advanced technology demonstrates that McGuire, being equipped with the standard Westinghouse ECCS, complies with the requirements of 10CFR50.46. Thus, peaking factors can be obtained with UHI removed that allow full operational flexibility. The burden of maintaining this complex equipment should be lifted to allow Duke Power to concentrate efforts on items that will improve plant safety.
Implementation of UHI removal requires new FSAR large and small break ECCS performance analyses. The completed LOCA reanalysis effort includes large break cases which utilize the BASH evaluation models and small break cases which utilize the NOIRUMP evaluation model. While BASH has not been approved at this time by the NRC, approval is anticipated by September 30, 1985.
2.1 LARGE DREAK LOCA A large break LOCA spectrum consisting of three double-ended cold-leg guillotine breaks with different discharge coefficients is presented in Appendix A, utilizing the BASH evaluation model.
In this model, the NRC-approved 1901 Evaluation Model versions of SATAN-V1, LOTIC, WREFLOOD and LOCTA-IV are employed.
The NRC-approved DART code, which models the reflood core heat transfer, has been combined with improved reflood thermal-hydraulic models to create BASH.
Doth minimum and maximum safeguards cases have been analyzed for the limiting discharge coefficient identified.
Appropriate cold leg accumulator parameters with UH1 removed input to the analyses refIcct the installation of new accumulator check valves.
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i 2.1 LARGE BREAK LOCA (Continuedl I
As shown by the analytical results detailed in Appendix A, the large break f
LOCA analysis performed demonstrates that McGuire will satisfy all Appendix K
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requirements af ter the removal of the UHI System and minor modifications to
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the Cold Leg Accumulators. The results justify an allowable core peaking j
factor limit, FQ, of 2.32 which is greater than the existing Technical Specification limit of 2.26.
All other input to the LOCA analysis described I
in Appendix A also remain conservative with respect to existing Technical Specification requirements, f
l 2.2 SMAt.L BREAK LOCA i
A spectrum of three small breaks performed with NOTRUMP is presented in Appendix A.
The NOTRUMP computer code has been approved following extensive l
NRC staff review. The results are well within all acceptance criteria limits I
of 10 CFR, 50.46.
t 3.0 NON-LOCA TRANSIENT t
The only FSAR non-LOCA transients for which the Reactor Coolant System is 1
predicted to depressurize to the UH1 system actuation range (1200-1300 psia)
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are the steamline break events.
Therefore, the analysis of all other i
accidents are unaffected by the proposed UH1 system elimination.
The Inadvertent Opening of a Steam Generator Relief or Safety Valve (FSAR Section 15.1.4) and Steam System Piping Failure (FSAR Section 15.1.5) analyses assume actuation of the UH1 system. These accidents have been reanalyzed without UHI system actuation. The results are presented in the FSAR page markups included in Appendix B.
The DN8 analysis has concluded that the ON8 design basis is met in all cases.
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t 4.0 CONTAINMENT RESPONSE ANALYSIS
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The containment response has been evaluated for comparison to peak temperature (steamline break transient) and peak pressure (LOCA) criteria.
I 4.1 STEAMl!NE BREAK - CONTAINMENT ANALYSIS The steamline break inside containment analysis for temperature and pressure response is presented in Section 6.2 of the McGuire FSAR. However, this analysis did not account for heat transfer to steam from the uncovered portion i
of the steam generator tube bundle in the calculation of mass / energy releases. The effect of this additional heat transfer is to cause i
superheating of the steam, resulting in an increase in the calculated containment temperature for ice condenser type containments. To support the NRC Containment Systems Branch review of this issue Westinghouse submitted l
Topical Report WCAP-8822-P-51, " Mass and Energy Releases Following a Steam Line Rupture." This report summarizes the results of the limiting cases from i
sensitivity studies which were performed to determine the mass / energy blowdowns to be used in the analysis for ice condenser containments.
A review of the sensitivity studies performed in support of the WCAP has determined that the RCS is predicted to depressurize to the VH1 system actuation range only for cases at l'ow power levels (and therefore low decay f
heat levels).
The peak steam enthalpies of these low power cases is well below that of the limiting cases presented in the WCAP.
Therefore, elimination of the UHI system for McGuire will have no impact on the
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conclusions of the containment response steamline break analysis since UH1 j
does not affect the calculated limiting mass / energy releases.
4.2 1.0CA-CONTAINMENT ANALYSIS I
1he removal of UH1 does not impact the existing analysis since the mass / energy release model employed has conservatively neglected the UH1 contribution.
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8995Q: 10/091985 4
5.0 SUMARY The detailed analyses performed to support the removal of the UHI system and provided via this report have demonstrated the validity of existing Technical Specifications and/or the proposed Technical Specification revisions previously submitted. The analysis results show adequate and acceptable performance of the ECCS and that McGuire continues to satisfy all applicable safety and regulatory requirements with UH1 removed.
89950:10/091985 5
TABLE OF CONTENTS i
)
SECTION PAGE i
1.0 Introduction 1
i 2.0
- ECCS Analysis 2
2.1 Largo Break LOCA 2
2.2 Small Break LOCA 3
4 i
i 3.0 Non-LOCA Translents 3
4.0 Containment Responso Analysis 4
4.1 Stcomlina Break - Containment Analysis 4
l 4.2 LOCA - Containment Analysis 4
i I
50 summary 5
i 1
3 4
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