ML073330483

Technical Specifications (TS) Changes TS-431 and TS-418 - Extended Power Uprate (EPU) - Response to Preliminary Findings on Steam Dryer Stress Analysis

ML073330483
Person / Time
Site:	Browns Ferry
Issue date:	11/21/2007
From:	Wetzel B Tennessee Valley Authority
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
TVA-BFN-TS-418, TVA-BFN-TS-431
Download: ML073330483 (19)

Text

This Document Contains Proprietary Information - Withhold Enclosure 1 from Public Disclosure Under 2.390(a) (4)

Tennessee Valley Authority, 1101 Market Street, Chattanooga, Tennessee 37402-2801 November 21, 2007 TVA-BFN-TS-431 TVA-BFN-TS-418 10 CFR 50.90 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Mail Stop OWFN, P1-35 Washington, D. C. 2055.5-0001 Gentlemen:

In the Matter of ) Docket Nos. 50--259 Tennessee Valley Authority ) 50-260 50-296 BROWNS FERRY NUCLEAR PLANT (BFN) - UNITS 1, 2, AND 3 -

TECHNICAL SPECIFICATIONS (TS) CHANGES TS-431 AND TS-418 -

EXTENDED POWER UPRATE (EPU) - RESPONSE TO PRELIMINARY FINDINGS ON STEAM DRYER STRESS ANALYSIS By letters dated June 28, 2004 and June 25, 2004 (ADAMS Accession Nos. ML041840109 and ML041840301, respectively),

TVA submitted license amendment applications to the NRC for the EPU of BFN Unit 1 and BFN Units 2 and 3, respectively. The proposed amendments would change the operating licenses to increase the maximum authorized core thermal power level of each reactor to 3952 megawatts. By letter dated July 27, 2007 (ML072130371), TVA submitted the completed BFN steam dryer stress analyses for Units 1, 2 and 3. On October 23, 2007, the NRC staff issued preliminary findings on the review of the steam dryer analyses which included six requests for additional information (RAI) . The enclosure to this letter provides TVA's responses to the six RAIs.

Printed on recycled paper

U.S. Nuclear Regulatory Commission Page 2 November 21, 2007 Please note that the information provided in Enclosure 1 contains information that Continuum Dynamics, Inc. (CDI) considers to be proprietary in nature and subsequently, pursuant to 10 CFR 2.390(a) (4), requests that such information be withheld from public disclosure. contains the redacted version of the response with the CDI proprietary material removed which is suitable for public disclosure. Enclosure 3 is an affidavit from CDI supporting this request.

TVA has determined that the additional information provided by this letter does not affect the no significant hazards considerations associated with the proposed TS changes. The proposed TS changes still qualify for a categorical exclusion from environmental review pursuant to the provisions of 10 CFR 51.22(c) (9).

No new regulatory commitments have been made in this submittal. If you have any questions regarding this letter, please contact James Emens at (256)729-7658.

I declare under penalty of perjury that the foregoing is true and correct. Executed on this 2 1 't day of November 2007.

Sincerely, Beth A. Wetzel t(

Manager, Corporate Nuclear Licensing and Industry Affairs

Enclosures:

1. Response to Preliminary Findings on Steam Dryer Stress Analysis (proprietary version)

2. Response to Preliminary Findings on Steam Dryer Stress Analysis (non-proprietary version)

3. CDI Affidavit

U.S. Nuclear Regulatory Commission Page 3 November 21, 2007 cc (Enclosure):

State Health Officer Alabama State Department of Public Health RSA Tower - Administration Suite 1552 P.O. Box 303017 Montgomery, Alabama 36130-3017 NRC Senior Resident Inspector Browns Ferry Nuclear Plant 10833 Shaw Road Athens, AL 35611-6970 Branch Chief U.S. Nuclear Regulatory Commission Region II Sam Nunn Atlanta Federal Center 61 Forsyth Street, SW, Suite 23T85 Atlanta, Georgia 30303-8931 Eva Brown, Project Manager U.S. Nuclear Regulatory Commission (MS 08G9)

One White Flint, North 11555 Rockville Pike Rockville, Maryland 20852-2739

ENCLOSURE 2 TENNESSEE VALLEY AUTHORITY BROWNS FERRY NUCLEAR PLANT (BFN)

UNITS 1, 2, AND 3 TECHNICAL SPECIFICATIONS (TS) CHANGES TS-431 AND TS-418 -

EXTENDED POWER UPRATE (EPU) - STEAM DRYER ANALYSIS REVIEW RESPONSE TO PRELIMINARY FINDINGS ON STEAM DRYER STRESS ANALYSIS (NON-PROPRIETARY VERSION)

Attached is the Non-Proprietary Version of the response to preliminary findings on steam dryer stress analysis.

NON-PROPRIETARY INFORMATION NRC Request EMEB.123/90 By letter dated July 27, 2007, Tennessee Valley Authority (TVA) provided a steam dryer analysis for Units 1, 2 and 3, using frequency-based methodology versus the direct integration time history analytical method that has been employed previously for Quad Cities (QC) 1 and 2, Dresden Units 2 and 3, and Vermont Yankee plants. ((

)) Provide verification and validation of the method by comparing the stresses resulted from finite element (FE) analysis using the direct integration time history method to that obtained from frequency-based analysis using the same FE model and applied transients.

TVA Reply to EMEB.123/90 Browns Ferry plans to provide the analysis prepared for Hope Creek to address this question. ((

)) A detailed documentation of thie comparison between time domain and frequency domain calculations will be provided to the staff in an analysis performed by CDI for Hope Creek.

NRC Request EMEB.124/91 In Table 8B of Continuum Dynamics Incorporated (CDI) reports 7-05P and 07-06P (Enclosures 1 and 2 of the July 27, 2007, letter), TVA reports the minimum stress ratio at current licensed thermal power (CLTP) of 0.96 for Unit 1 and 0.49 for Units 2 and

3. These low ratios (< 1.0) imply that the maximum stress of the BFN steam dryers exceeds the fatigue limit at CLTP for the current plant configuration. TVA indicated in Section 5.3 that the high stress was due to a strong pressure peak identified at 218 Hz. This peak was filtered out of applied time history to dramatically reduce the stresses shown in Table 9B where the mLnimum stress ratios are all greater than 1.0. TVA indicated that the elimination of 218 Hz peaks can be achieved by plugging eight unused standpipes in main steam lines (MSLs) 'A' and 'D',

and four in MSLs 'B' and 'C'. TVA is requested to demonstrate that the plugging of these standpipes eliminates the 218 Hz peak.

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NON-PROPRIETARY INFORMATION TVA Reply to EMEB.124/91 In order to mitigate the most limiting component of steam dryer cyclic stress calculated at CLTP conditions in CDI reports07-05P and 07-06P, Browns Ferry plans to install acoustic vibration suppressors (AVSs) in the eight unused safety relief valve (SRV) standpipe locations on the main steam lines (MSL) which are in the flow stream. The standpipes in the flow stream are located on MSLs A and D only. MSLs B and C have four similar standpipes which are located in dead legs outside the flow stream and would not contribute to the 218 Hz peaks.

As discussed in Section 5.3 of CDI reports07-05P and 07-06, the dominant component of stress and load occurs at 218 Hz. Steam line data from Units 1 and 2 indicate a strong acoustic response at about 218 Hz. Additionally, accelerometers were installed on some SRV positions in BFN Units 1, 2, and 3 to obtain baseline vibration data during power ascension. This accelerometer data confirms a significant vibration near 220 Hz on all three units.

Investigation has identified the unused SRV standpipes as the source of this component. Based on a standpipe length of 20 +/-

0.3 inches from fabrication drawings, the quarter-wave resonant frequency of the standpipe chamber was found to range from 218 to 225 Hz. The flow rate at which the peak responses occurred corresponds to a Strouhal number indicative of the second shear wave instability mode (i.e., vortex shedding mode). The MSL data taken during power ascension indicates a sharp increase in amplitude at the standpipe quarter-wave frequencies at main steam flow rates corresponding to approximately 3.4 Mlb/hr for MSLs A and D. As main steam flow was further increased, the amplitudes of the quarter-wave responses began to decrease. This is very indicative of vortex shedding-induced acoustic resonance, which is strongly dependent on flow velocity.

Based on this investigation, TVA has concluded that the unused SRV standpipes are a significant source of acoustic loading. As such, TVA plans to directly address dryer loading by eliminating the standpipes as a source of excitation. The approach being taken to eliminate the 218 Hz resonance in MSLs A and D is to increase the fundamental acoustic resonant frequencies (i.e.,

quarter-wave frequencies) of the standpipes by decreasing their effective lengths through the installation of AVSs, so that resonance due to vortex shedding will not occur at main steam flow rates up through EPU conditions. Accordingly, AVS devices will be installed in the eight standpipes in MSLs A and D which are in the flow stream. AVS devices will not be installed in the four unused standpipes on MSLs B and C because these branches are located on the dead-leg portion of the line and are not exposed E2-2

NON-PROPRIETARY INFORMATION to main steam flow. Figure EMEB.124/91-1 is a sketch showing the design of the AVS. An AVS design was performed which includes sensitivity analyses to demonstrate that the fundamental acoustic resonant frequencies of the modified standpipe configurations are sufficiently increased to avoid resonance at all flow rates up through EPU.

Currently, TVA plans to install the AVS devices on BFN Unit 3 during the upcoming Spring 2008 outage. Following startup from the outage, MSL strain gage data will be taken to confirm that the AVS provides the intended effect on the acoustic frequency spectra.

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NON-PROPRIETARY INFORMATION Figure EMEB.124/91-1 Acoustic Vibration Suppressor 26' PIPE (REF)

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NON-PROPRIETARY INFORMATION NRC Request EMEB.125/92 It appears that all three units were analyzed utilizing MSL strain gage data from BFN Unit 2. To assess the applicability of the use of Unit 2 steam line data for the Unit 1 steam dryer stress analysis, a comparison of the Unit 1 and Unit 2 main steam line strain gage data was performed in Enclosure 6F which need to be reviewed in detail. No main steam strain gage data is available for Unit 3. It is noted that, in the public meeting on April 6, 2007, the Nuclear Regulatory Commission staff advised TVA that the application should show the similarity between Units 2 and 3 steam dryers since Unit 3 will not be instrumented by TVA* TVA is requested to demonstrate that Unit 2 MSL strain gage data can be applied to Unit 3 steam dryer stress analysis under EPU conditions.

TVrA Reply to EMEB.125/92 The BFN steam dryer stress analyses were provided by the July 27, 2007, submittal in CDI Report No.07-05P (Enclosure 1), "Finite Element Model for Stress Assessment of Browns Ferry Nuclear Unit 1 Steam Dryer to 250 Hz," and CDI Report No.07-06P (Enclosure 2), "Finite Element Model for Stress Assessment of Browns Ferry Nuclear Unit 2 and 3 Steam Dryers to 250 Hz." Due to the availability of MSL strain gage data and the schedule for performing the BFN steam dryer stress analyses, all three units were analyzed utilizing MSL strain gage data from BFN Unit 2.

Unit 2 strain gage data was obtained in October 2006 following a mid-cycle outage. Unit 1 strain gage data was taken during the unit restart from the extended outage during the last half of June 2007.

To assess the applicability of the use of Unit 2 steam line data for the Unit 1 steam dryer stress analysis, a comparison of the Unit 1 and Unit 2 MSL strain gage data was performed. The evaluation was provided by the July 27, 2007, submittal in CDI Technical Memorandum No.07-26P (Enclosure 6), "Comparison of Browns Ferry Nuclear Unit 1 and Unit 2 Main Steam Line Strain Gage/Pressure Readings." This evaluation concluded that the use of the Unit 2 data for the Unit 1 analysis results in conservative prediction of dryer stresses on Unit 1.

Unit 2 steam line strain gage data was utilized in the stress analyses for all three units based on the similarity between the physical locations of relevant components on all three units.

Component as-built locations (not field verified) are provided for each steam line in Table EMEB.125/92-1.

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NON-PROPRIETARY INFORMATION Currently, TVA plans to install steam line strain gages on BFN Unit 3 during the upcoming Spring 2008 outage. Following startup from the outage, MSL strain gage data will be taken to confirm the similarity of acoustic data to Unit 2.

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NON-PROPRIETARY INFORMATION Table EMEB.125/92-1 BFN Units 1, 2, and 3 Steam Line Measurements Unit 1 Unit 2 Unit 3 Segment # Item Segment Cumulative Segment Cumulative Segment Cumulative span (ft) span (ft) span (ft) span (ft) span (ft) span (ft)

Main Steam Line A Al to A2 Noz to first Ell 4.000 4.000 3.833 3.833 4.000 4.000 A2 to A3 Ell to 5D Bend 35.792 39.792 35.375 39.208 35.395 39.395 A3 to A4 5D Bend to 2nd Ell 12.417 52.209 13.000 52.208 12.833 52.228 A4 to A5 2nd Ell to 71ASRV 2.833 55.042 2.880 55.088 2.880 55.108 A5 to A6 71ASRV to SP 2.646 57.688 2.660 57.748 2.750 57.858 A6 to A7 SP to SP 4.958 62.646 4.958 62.706 5.000 62.858 A7 to A8 Sp to 71MSRV 3.125 65.771 3.125 65.831 3.458 66.316 A8 to A9 71M SRV to SP 6.250 72.021 6.167 71.998 6.167 72.483 A9 to A10 SP to SP 3.167 75.188 3.125 75.123 3.125 75.608 Ai0 to All SP to 71BSRV 3.080 78.268 3.104 78.227 3.104 78.712 All to A12 71B to 3rd Ell 7.417 85.685 7.290 85.517 7.354 86.066 A12 to A13 3rd Eli to 4th Ell 18.416 104.101 18.390 103.9.07 18.500 104.566 A13 to A14 4th Ell to 1st MSIV 5.080 109.181 5.310 109.217 5.375 109.941 A14 to A15 1st to 2nd MSIV 24.604 133.785 24.680 133.897 24.559 134.500 Main Steam Line B Bl to B2 Noz to 1st Ell 3.871 3.871 4.120 4.120 4.000 4.000 B2 to B3 1st Eli to 5D Bend 35.250 39.121 35.030 39.150 35.969 39.969 B3 to B4 5D Bend to Hdr 11.330 50.451 9.790 48.940 11.167 51.136 B4 to B5* Tee @ Hdr to SP 3.708 54.159 3.310 52.250 3.667 54.803 B5 to B6* SP to SP 5.042 59.201 5.270 57.520 5.083 59.886 B6 to HPCI* SP to HPCI Con 11.042 70.243 11.386 68.906 11.167 71.053 HPCI to B7* HPCI to 71D SRV 1.500 71.743 1.265 70.171 1.500 72.553 B7 to B8* 71D to 71C SRV 3.313 75.056 3.790 73.961 3.417 75.970 E2-7

NON-PROPRIETARY INFORMATION Unit 1 Unit 2 Unit 3 Segment # Item Segment Cumulative Segment Cumulative Segment Cumulative span (ft) span (ft) span (ft) span (ft) span (ft) span (ft)

B8 to B9 capped end* 71C to End Hdr Cap 1.760 76.816 2.750 76.711 1.750 77.720 Tee @ Hdr Con to B4 to B10 71ESRV 6.658 57.109 6.580 55.520 6.667 57.803 B10 to BlI 71E to 71FSRV 3.396 60.505 3.370 58.890 3.438 61.241 BII to B12 71F to 2nd Ell 7.031 67.536 7.280 66.170 7.458 68.699 B12 to B13 2nd Ell to 3rd Ell 18.480 86.016 18.000 84.170 18.125 86.824 B13 to B14 3rd Ell to 4th Ell 4.667 90.683 4.582 88.752 4.750 91.574 B14 to B15 4th Ell to 1st MSIV 7.211 97.894 7.050 95.802 6.850 98.424 B15 to B16 1st to 2nd MSIV 23.020 120.914 22.830 118.632 22.850 121.274 Main Steam Line C Cl to C2 Noz to 1st Ell 4.000 4.000 3.792 3.792 4.063 4.063 C2 to C3 1st Ell to 5D Bend 34.583 38.583 34.083 37.875 34.333 38.396 C3 to C4 5D Bend to Tee @ Hdr 12.000 50.583 12.7.70 50.645 12.790 51.186 C4 to C5* Tee @ Hdr to SP 3.5 54.083 2.36 53.005 3.7 54.886 C5 to C6" SP to SP 5.000 59.083 5.130 58.135 5.063 59.949 C6 to C7* Sp to 71H SRV 13.000 72.083 12.420 70.555 12.583 72.532 C7 to C8" 71H to 71G SRV 3.417 75.500 3.402 73.957 3.385 75.917 C8 to C9 Capped End* 71G to Hdr Cap 1.729 77.229 1.694 75.651 1.693 77.610 C4 to C10 (RCIC) Tee to 71JSRV 9.875 60.458 8.980 59.625 10.100 61.286 Clo to Cll 71J to 2nd Ell 6.583 67.041 7.547 67.172 7.541 68.827 ClI to C12 2nd Ell to 3rd Ell 18.427 85.468 18.250 85.422 18.740 87.567 C12 to C13 3rd Ell to 4th Ell 4.375 89.843 4.580 90.002 4.580 92.147 C13 to C14 4th Ell to 1st MSIV 6.906 96.749 6.938 96.940 6.958 99.105 C14 to C15 1st to 2nd MSIV 23.604 120.353 23.750 120.690 23.646 122.751 E2-8

NON-PROPRIETARY INFORMATION Unit 1 Unit 2 Unit 3 Segment # Item Segment Cumulative Segment Cumulative Segment Cumulative span (ft) span (ft) span (ft) span (ft) span (ft) span (ft)

Main Steam Line D DI to D2 Noz to ist Ell 4.000 4.000 4.000 4.000 4.000 4.000 D2 to D3 1st Ell to 5D Bend 35.531 39.531 35.210 39.210 35.188 39.188 D3 to D4 5D Bend to 2nd Ell 12.417 51.948 12.970 52.180 12.500 51.688 D4 to D5 2nd Eli to 71KSRV 3.250 55.198 2.890 55.070 3.000 54.688 D5 to D6 71K to SP 2.677 57.875 2.685 57.755 2.750 57.438 D6 to D7 SP to SP 4.938 62.813 4.918 62.673 5.000 62.438 D7 to D8 Sp to 71NSRV 3.080 65.893 3.080 65.753 3.167 65.605 D8 to D9 71N to SP 6.125 72.018 6.196 71.949 6.208 71.813 D9 to DI0 SP.to SP 3.167 75.185 3.063 75.012 3.063 74.876 D10 to D0I SP to 71LSRV 3.040 78.225 3.104 78.116 3.125 78.001 DII to D12 71LSRV to 3rd Ell 7.080 85.305 7.260 85.376 7.167 85.168 D12 to D13 3rd Ell to 4th Ell 18.500 103.805 18.415 103.791 17.958 103.126 D13 to D14 4th Ell to 1st MSIV 5.145 108.950 5.365 109.156 5.489 108.615 D14 to DI5 1st to 2nd MSIV 24.906 133.856 25.150 134.306 24.844 133.459

• Dead leg locations with no flow E2-9

NRC Request EMEB.126/93 CDI Report No.07-09P, Methodology to Predict Full Scale Steam Dryer Loads from In-Plant Measurements with the Inclusion of a Low Frequency Hydrodynamic Contribution, in Enclosure 3 of the July 27, 2007, letter provides a methodology for predicting steam dryer loads including a low-frequency hydrodynamic contribution.

I((

TVA Reply to EMEB.126/93 No additional data sets are available to TVA to undertake further validation of ACM Rev. 4. TVA's position is that comparison of prediction against the Quad Cities data is favorable. It should be noted that there are low frequency loads present at Quad Cities as demonstrated in Figure 126/93-1 below. ((

E))

((1 E2-10

NRC Request EMEB.127/94

((

TVA Reply to EMEB.127/94

[I E2-11

NRC Request EMEB.128/95 CDI Report No.07-10P, Acoustic and Low Frequency Hydrodynamic Loads at CLTP Power level on Browns Ferry Nuclear Unit 2 Steam Dryer to 250 Hz, discusses the bias errors and uncertainties of the Acoustic Circuit Model analysis. Discuss how the evaluation focuses on resonance peaks measured at current operating conditions and predicted for EPU conditions when assuming frequency intervals for evaluation of bias error and uncertainty of the ACM analysis.

TVA Reply to EMEB.128/95 As shown in Table 5.1 of CDI report 07-10P, the ACM Rev. 4 bias and uncertainty factors for all BFN units are applied at fixed frequency intervals based on correlation of ACM Rev. 4 with QC2 data. The only exception to this is that the total bias and uncertainty factor of 75% applied to the 153 to 157 Hz range for QC2 was shifted to the 216 to 220 Hz range for BFN. The 216 to 220 Hz range coincides with a 218 Hz peak observed in all BFN units and is attributed to unused SRV standpipe acoustic resonance. Even though the BFN analysis considers that this resonance is mitigated by the installation of acoustic vibration suppressors, the 75% total bias and uncertainty factor is still applied in the 216 to 220 Hz band since no other similar resonance has been identified.

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I ENCLOSURE 3 TENNESSEE VALLEY AUTHORITY BROWNS FERRY NUCLEAR PLANT (BFN)

UNITS 1, 2, AND 3 TECHNICAL SPECIFICATIONS (TS) CHANGES TS-431 AND TS-418 -

EXTENDED POWER UPRATE (EPU) - STEAM DRYER ANALYSIS REVIEW AFFIDAVIT Attached is CDI's affidavit for the proprietary information contained in the response to preliminary findings on steam dryer stress analysis provided in Enclosure 1.

6 ,4 -w 4MOW Continuum Dynamics, Inc-(609) 538-0444 (609) 538-0464 fax 34 Lexington Avenue Ewing, NJ 08616-2302 AFFIDAVIT Re: Browns Ferry Nuclear Plant (BFN) - Units 1, 2 and 3 - Technical Specifications (TS) Changes TS-431 and TS-418 - Extended Power Uprate (EPU) - Response to Preliminary Findings on Steam Dryer Stress Analysis I, Alan J. Bilanin, being duly sworn, depose and state as follows:

1Ihold the position of President and Senior Associate of Continuum Dynamics, Inc. (hereinafter referred to as C.D.I.), and I am authorized to make the request for withholding from Public Record the Information contained in the documents described in Paragraph 2. This Affidavit is submitted to the Nuclear Regulatory Commission (NRC) pursuant to 10 CFR 2.390(a)(4) based on the fact that the attached information consists of trade secret(s) of C.DJ. and that the NRC will receive the information from C.D.I. under privilege and in confidence.

2. The Information sought to be withheld, as transmitted to TVA Browns Ferry as attachment to C.D.I. Letter No. 07212 dated 19 November 2007 "Browns Ferry Nuclear Plant (BFN) - Units 1, 2 and 3 - Technical Specifications ("S) Changes TS- 431 and TS-418 Extended Power Uprate (EPU) - Response to Preliminary Findings on Steam Dryer Stress Analysis".

3. The Information summarizes:

(a) a process or method, including supporting data and analysis, where prevention of its use by C.D.I.'s competitors without license from C.D.I. constitutes a competitive advantage over other companies; (b) Information which, if used by a competitor, would reduce his expenditure of resources or improve his competitive position in the design, manufacture, shipment, installation, assurance of quality, or licensing of a similar product; (c) Information which discloses patentable subject matter for which it may be desirable to obtain patent protection.

The information sought to be withheld is considered to be proprietary for the reasons set forth in paragraphs 3(a), 3(b) and 3(c) above.

4. The Information has been held in confidence by C.D.I., its owner. The Information has consistently been held in confidence by C.D.I. and no public disclosure has been made and it is not available to the public. All disclosures to

.1, .

third parties, which have been limited, have been made pursuant to the terms and conditions contained in C.D.I.'s Nondisclosure Secrecy Agreement which must be fully executed prior to disclosure.

5. The Information is a type customarily held in confidence by C.D.I. and there is a rational basis therefore. The Information is a type, which C.D.I. considers trade secret and is held in confidence by C.D.I. because it constitutes a source of competitive advantage in the competition and performance of such work in the industry. Public disclosure of the Information is likely to cause substantial harm to C.D.l's competitive position and foreclose or reduce the availability of profit-making opportunities.

I declare under penalty of perjury that the foregoing affidavit and the matters stated therein are true and correct to be the best of my knowledge, information and belief.

Executed on this _ý_r'day of 2007.

Contit it~iiaicsInc.

Subscribed and sworn before me this day: //- /' --

• 0 c) a -ui=ie ,Notarry Public EILEEN P. BURMEISTER NOTARY PUBLIC OF NEW JERSEY MY COMM. EXPIRES MAY 6, 2012