ML061290566

Revision 3 to Steam Dryer Monitoring Plan

ML061290566
Person / Time
Site:	Vermont Yankee File:NorthStar Vermont Yankee icon.png
Issue date:	05/04/2006
From:	Ted Sullivan Entergy Nuclear Northeast, Entergy Nuclear Operations
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
%dam200606, BVY 06-042, TAC MC0761
Download: ML061290566 (29)

Text

1f Entergy Nuclear Northeast Entergy Nuclear Operations, Inc.

Vermont Yankee P.O. Box 0500 185 Old Ferry Road E ntergyv Brattleboro, VT 05302-0500 v

}

Tel 802 257 5271 May 4, 2006 Docket No. 50-271 BVY 06-042 TAC No. MC0761 ATTN: Document Control Desk U.S. Nuclear Regulatory Commission Washington, DC 20555-0001

Subject:

Vermont Yankee Nuclear Power Station Revision 3 to Steam Dryer Monitoring Plan

References:

1) Entergy letter to U.S. Nuclear Regulatory Commission, "Vermont Yankee Nuclear Power Station, License No. DPR-28 (Docket No. 50-271), Technical Specification Proposed Change No. 263, Extended Power Uprate," BVY 03-80, September 10, 2003

2) Entergy letter to U.S. Nuclear Regulatory Commission, "Vermont Yankee Nuclear Power Station, Revision 2 to Steam Dryer Monitoring Plan,"

BVY 06-039, April 20, 2006 This letter provides updated information pursuant to a regulatory commitment made in connection with the application by Entergy Nuclear Vermont Yankee, LLC and Entergy Nuclear Operations, Inc. (Entergy) for a license amendment (Reference 1, as supplemented) to increase the maximum authorized power level of the Vermont Yankee Nuclear Power Station (VYNPS) from 1593 megawatts thermal (MWt) to 1912 MWt. includes a revision (Revision 3) to the Steam Dryer Monitoring Plan (SDMP) that was previously provided in Reference 2. The SDMP will remain in effect until License Condition 3.M expires. The SDMP, together with the Extended Power Uprate (EPU) Power Ascension Test Procedure (PATP), provides for monitoring, inspecting, evaluating, and prompt action in response to potential adverse flow effects on the steam dryer as a result of power uprate operation. These actions provide assurance of the continued structural integrity of the steam dryer under EPU conditions. Attachment 2 provides the basis, consistent with License Condition 3.M.4, for why 1-his change does not require prior NRC approval.

Entergy has performed necessary calculations and evaluations to ensure for safe operation at the 1912 MWt power level.

. 4-oI

BVY 06-042 Docket No. 50-271 Page 2 of 2 There are no new regulatory commitments contained in this submittal.

If you have any questions or require additional information, please contact Mr. James DeVincentis at (802) 258-4236.

Sincerely, Site'Vice President Vermont Yankee Nuclear Power Station Attachments (2) cc:

Mr. Samuel J. Collins (w/o attachments)

Regional Administrator, Region 1 U.S. Nuclear Regulatory Commission 475 Allerndale Road King of Prussia, PA 19406-1415 Mr. Richard B. Ennis, Project Manager Project Cirectorate I Division of Licensing Project Management Office of Nuclear Reactor Regulation U.S. Nuclear Regulatory Commission Mail Stop 0-8B1 Washing ton, DC 20555 USNRC Resident Inspector Entergy Nuclear Vermont Yankee, LLC P.O. Box 157 Vernon, Vermont 05354 Mr. David O'Brien, Commissioner VT Department of Public Service 112 State Street - Drawer 20 Montpelier, Vermont 05620-2601

BVY 06-042 Vermont Yankee Nuclear Power Station Steam Dryer Monitoring Plan Revision 3

Entergy Vermont Yankee Steam Dryer Monitoring Plan Revision 3 May 4, 2006 Prepared By I/

'V6M/1 Reviewed E Approved B craig J. Nichols Date Cues CallOan Date

&r,6

\\i~~eyfuss Date-Date

Entergy Vermont Yankee Steam Dryer Monitoring Plan List of Revisions Revision Date Changes Original February 26, 2006 Original Issue 1

March 25, 2006 Incorporated new ACM.

Incorporated revisions to FEM.

Updated uncertainty evaluation and Limit Curves based on updated models and strain gage data evaluation at 1671 MWt.

2 April 20, 2006 Updated uncertainty evaluation and Limit Curves based on updated strain gage data evaluation at 1792 MWt.

3 May 4, 2006 Incorporated allowance for use of FEM/Strain Gage Evaluation (F-factor).

Provided allowance for up to 1 Hz shift in limit curve peak frequencies.

Updated Limit Curves Based on 1872 MWt Data Clarified schedule for completion of final Full Power Steam Dryer Load Analysis

Page 1 of 20 Rev. 3 VERMONT YANKEE NUCLEAR POWER STATION STEAM DRYER MONITORING PLAN Introduction and Purpose The Vermont Yankee Steam Dryer Monitoring Plan (SDMP) describes the course of action for monitoring and evaluating the performance of the Vermont Yankee Nuclear Power Station (VYNPS) steam dryer during power ascension testing and operation above 100% of the original licensed thermal power (OLTP), i.e., 1593 MWt, to the full 120% extended power uprate (EPU) condition of 1912 MWt to verify acceptable performance. The SDMP also addresses long-term actions necessary to implement proposed License Condition 3.M. Through operating limits, periodic surveillances, and required actions, the impact of potentially adverse flow effects on the structural integrity of the steam dryer will be minimized.

The SDMP also provides information about the equipment and computer analysis methodologies used to monitor Steam Dryer performance.

Unacceptable steam dryer performance is a condition that could challenge steam dryer structural integrity and result in the generation of loose parts, cracks or tears in the steam dryer that result in excessive moisture carryover.

During reactor power operation, performance is demonstrated th rough the measurement of a combination of plant parameters.

Scope The SDMP is p-imarily an initial power ascension test plan designed to assess steam dryer performance from 100% OLTP (i.e., 1593 MWt) to 120% OLTP (i.e., 1912 MWt) and to perform confirmatory inspections for a period of time following initial and continued operation at uprated power levels. Flower ascension to 120% OLTP will be achieved in a series of power step increases and holds at plateaus corresponding to 80 MWt increments above OLTP. Elements of this plan will be implemented before EPU power ascension testing, and others may continue after power ascension testing.

There are three main elements of the SDMP:

1. Slow and deliberate power ascension with defined hold points and durations, allowing time for monitoring and analysis;

2. A detailed power ascension monitoring and analysis program to trend steam dryer performance (primarily through the monitoring of steam dryer load signals and moisture carryover); and

3. A long term inspection program to verify steam dryer performance at EPU operating condition s.

Several elements of the SDMP also provide for completion of the necessary actions to satisfy the requirements of license conditions associated with the EPU license amendment.

A complete tabulation of the provisions of the license condition and the implementing strategy to complete them is contained in Table 3.

Page 2 of 20 Rev. 3 Power Ascension VYNPS procedure ERSTI-04-VY1-1409-000, "Power Ascension Test Procedure for Extended Power Conditiorns 1593 to 1912 MWth," (PATP) will provide controls during power ascension testing and confirm acceptable plant performance.

Other procedures may be entered to conduct specialized testing, such as condensate and feedwater testing. The VYNPS power ascension will occur over an extended period with gradual increases in power, hold periods, and engineering analyses of monitored data that must be approved by station management.

Relevant data and evaluations will be transmitted to the NRC staff in accordance with the provisions of the license condition. The PATP includes:

1. Power ascension rate of 16 MWt/hr;

2. Hourly monitoring of steam dryer performance during power ascension (required by License Condition 3.M);

3. Four hou holds at each 40 MWt; and

4. Minimum 96 hour0.00111 days <br />0.0267 hours <br />1.587302e-4 weeks <br />3.6528e-5 months <br /> holds at each 80 MWt power plateau to perform steam dryer analysis allowing ior NRC review, as appropriate (required by License Condition 3.M).

Monitoring Plans Table 1 outlines the steam dryer surveillance requirements during reactor power ascension testing for EPU. The monitoring of moisture carryover and main steam line (MSL) pressure data provide measures for ensuring acceptable performance of the steam dryer.

Frequent monitoring of these parameters will provide early detection capability of off-normal performance.

Proposed License Condition 3.M will require that steam dryer performance criteria are met and prompt action is taken if unacceptable performance is detected. Entergy has established two performance levels (Level 1 criteria and Level 2 criteria) as described in Table 2 for evaluating steam dryer performance during EPU power ascension testing. The Level 1 criteria correspond to the limits specified in the proposed license condition, while the Level 2 criteria are operating action levels that may indicate reductions in margin.

The comparison of measured plant data against defined criteria derived from the steam dryer analyses described below provide a means to assess continued steam dryer structural integrity under EPU cond tions.

Main Steam Fluctuating Pressure Monitoring System (Details contained in VYC-3001)

Main Steam line Strain Gages Entergy has nstalled strain gages at two locations on each of the four MSLs in the primary containment and a data acquisition system (DAS) designed to reduce uncertainties in the evaluation of steam dryer loads. These strain gages and the associated data acquisition system have been selected and configured to maximize sensitivity and reliability while reducing data uncertainty.

• Acoustic Circuit Model (ACM)

The CDI Acoustic Model has been improved based on results of the instrumented Steam Dryer at Exelon's Quad Cities Station.

The revision has resulted in reduced uncertainty aid a more conservative representation of the peak frequencies.

Page 3 of 20 Rev. 3 Finite Element Model (FEM)

In response to industry operating experience with steam dryer cover plate cracking, the ANSYS FEM has been updated to include more refined analysis of key dryer structural components such as the lower cover plate, the gussets, gusset shoes, and associated welds.

Since Entergy/GE started using the FEM to evaluate stresses on the VY dryer during power ascension, the contribution of the key in-plant forcing frequencies has been calculated. By understanding the impact on stress due to increases in each of the key in-plant forcing frequencies, the change in steam dryer stress with changes in strain gage signal can be determined directly. Use of these frequency contributions (known as 'F' factors) allows the relationship of the strain gages, ACM, and FEM to be more directly determined based on the plant-specific assessment of ACM/FEM results.

In addition, the Steam Dryer Strain Gage Monitoring and FEM frequency assessments have determined tiat in-plant acoustic signal frequencies have been shown to change slightly with increased stream flow. While the observed changes (<1Hz) have negligible impact to the dryer structure, they can result in an unnecessary challenge to the limit curve. To address the shifts of in-plant acoustic frequencies, the limit curve may be shifted to the right or to the left less than or equal to 1 Hz. The limit curve criteria is considered satisfied as long as the acoustic signal from the shifted peak falls under the shifted limit curve.

Acoustic Circuit Analysis (ACA) System Uncertainty Evaluation The VY Acoustic Circuit Model (ACM) has been updated. The revised ACM was developed to bound maximum pressure loads from three sets of test data from the instrumented QC2 dryer testing performed in 2005. This updated ACM uncertainty assessment is based on the enhanced VY strain gage and data acquisition system and the revised CDI Bounding Pressure model parameters. The Scale Model Test (SMT) benchmark evaluation and previous 790 MWe QC2 benchmark assessment that provided the uncertainty bases for the prior ACM have been accordingly deleted from this calculation.

The overall system uncertainty is based on the combination of the uncertainties of each of the elements. The uncertainty in the ACM loads is derived from the following sources:

o Uncertainty of the ACM to conservatively predict pressure response at the significant frequencies o Uncertainty introduced by differences in sensor locations between QC2 and VY o Uncertainty introduced as a result of the ability of the ACM or Structural Model to match load and structural frequencies o Uncertainty resulting from strain gage and measure uncertainties.

These uncertainties will then be combined by the square root sum of the squares (SRSS) method to assess the ACM load uncertainty.

As calculated in VYC-3001 the overall system uncertainty is 43%. This value is used in the determinatior of the reduction of the limit curve factor resulting in the final limit curve, shown as Figures 1 through 8 of the SDMP. The contribution of each of the factors noted above is as follows:

Page 4 of 20 Rev. 3 Maximurn Uncertainty of the ACA Methodology (per VYC 3001 Rev. 2)

ACM ability to conservatively match peak response at the highest frequencies:

32%

Difference in Sensor Locations from QC2 to VY 7%

Ability of ACM or Structural Model to match response frequencies:

25%

SG and DAS ability to measure pressure in Pipe 11%

Uncertainty of Dryer Pressure data Measurements at QC2 3%

Combined Uncertainty by Square Root Sum of the Squares 43%

The uncertainty of the ACM to predict peak response at observed dryer acoustic frequencies is the largest contributor to overall ACA load uncertainty. The other uncertainties including the sensor location uncertainty, frequency uncertainty, pipe pressure measurement uncertainty, and QC2 dryer pressure measurement uncertainty are independent elements of uncertainty because they are derived from unrelated variables such as location, frequency, independent benchmark assessment, and detection equipment. Therefore the SRSS combination methodology is appropriate.

CFD Load Uncertainty (Remains unchanged from Revision 0 of VYC 3001)

The CFD predictions using the Large Eddy Simulation runs for VY are on average 118%

above the RAS values of in-plant data with a standard deviation of 82%. Therefore a conservative estimate of uncertainty is 118% - 82% = +36%. This would support 0%

uncertainty for the CFD load. Conservatively, VY has maintained a 15% CFD load uncertainty in the Limit Curve Factor assessment.

The CFD analysis with the +/-10% change in load step had an impact on the limiting stress by 4%. The efore the CFD frequency uncertainty is determined to be 4%. The total CFD uncertainty; LincCFD= sqrt(15A2 + 4A2) = 16%.

System Monitoring Requirements o

During power ascension, steam dryer performance will be monitored hourly through the evaluation of pressure fluctuation data collected from strain gages installed on the MSLs.

o The strain gage data collected hourly during power ascension will be compared against the stress limit curve that is provided as Figures 1 - 8 of the SDMP and is based on Entergy Calculation VYC-3001.

If any frequency peak from the MSL strain gage data exceeds the stress limit curve (Level 1), Entergy will reduce the reactor power to a level at which the stress limit curve is not exceeded.

o Additionally, Entergy will monitor data collected from accelerometers mounted to the main steam piping inside the drywell to provide additional insights into the strain gage signals.

o During hold points at each 80 MWt power level above current licensed thermal power, the collected data, along with a comparison to the steam dryer limit curve, will be transmitted to the NRC staff.

o For any circumstance requiring a revision to the steam dryer limit curve, Entergy will resolve uncertainties in the steam dryer analysis and provide the results of that evaluation to the NRC staff prior to further increases in reactor power.

o Entergy will resolve uncertainties in the steam dryer analysis with the NRC staff within 90 days of issuance of the EPU license amendment. If resolution is not made within this time interval, reactor operation will not exceed 1593 MWt. These planned actions are in compliance with proposed License Condition 3.M.

Page 5 of 20 Rev. 3 Moisture Carryover Moisture carryover trending provides an indicator of steam dryer integrity. At each 40 MWt step, moisture carryover data will be taken and compared to the predetermined acceptance criteria (Table 2).

Level 1 criterion (0.35%) is based on the maximum analyzed value.

The data taken at each 80 MWt plateau will be evaluated and documented in the assessment sent to the NRC for information.

Other Monitoring Plant data that may be indicative of off-normal steam dryer performance will be monitored during powEr ascension (e.g., reactor water level, steam flow, feed flow, steam flow distribution between the individual steam lines). Plant data can provide an early indication of unacceptable steam dryer performance.

The enhanced monitoring of selected plant parameters will be controlled by the PATP and other plant procedures.

NRC Notificatiorls In accordance with proposed License Condition 3.M., at discrete power levels, and if the steam dryer stress limit curve (i.e., Level 1 criterion) is exceeded, Entergy will provide notifications to the NRC staff consisting of data and evaluations performed during EPU power ascension testing above 1593 MWt. Detailed discussions regarding new plant data, inspections, and evaluations will be held with NRC staff upon request. The designated NRC point of contact for such information is the NRC Project Manager for the VYNPS EPU.

• The results of the SDMP will be submitted to the NRC staff in a report within 60 days following the completion of all EPU power ascension testing. This will include the final full EPU power performance criteria spectra (i.e., steam dryer stress limit curve). In accordance with License Condition 3.M the uncertainty questions associated with the ACM will be resolved and submitted to the NRC staff within 90 days of license amendment issuance.

Contemporary data and results from steam dryer monitoring will be available on-site for review by NRC inspectors as it becomes available.

The written report on steam dryer performance during EPU power ascension testing will include evaluations or corrective actions that were required to obtain satisfactory steam dryer performance. The report will include relevant data collected at each power step, comparisons to performance criteria (design predictions), and evaluations performed in conjunction with steam dryer structural integrity monitoring.

Long Term Moni:oring The long-term monitoring of plant parameters potentially indicative of steam dryer failure will be conducted, as recommended by General Electric Service Information Letter 644, Rev. 1 and consistent with License Condition 3.M.

Moisture Carryover Per VYNPS station operating procedure OP-0631, "Radiochemistry," moisture carryover is periodically monitored for moisture carryover during normal plant operations. VYNPS off-normal procedure ON-3178, "Increased Moisture Carryover," provides guidance to evaluate any elevated moisture carryover results including that resulting from potential vessel internals

Page 6 of 20 Rev. 3 damage.

This monitoring will also provide insight into changes in moisture carryover values during changing reactor core configurations (control rod patterns)

Strain Gage Monitoring As the strain gages will remain operational and can provide for future data collection, additional strain gage mon toring will be performed as determined appropriate during the remainder of the operating cycle following EPU implementation.

Inspections The VYNPS steam dryer will be inspected during the refueling outages scheduled for the Spring 2007, Fall 2008, and Spring 2010.

The inspections conducted after power uprate implementation will be comparable in scope to the inspection conducted during the Spring 2004 refueling outage and will be in accordance with the guidance in SIL 644, Rev. 1.

Reporting to NRC, Steam Dryer Visual Inspections:

The results of the visual inspections of the steam dryer conducted during the next three refueling outages shall be reported to the NRC staff within 60 days following startup from the respective refueling outage.

Page 7 of 20 Rev. 3 Table 1 Steam Dryer Surveillance Requirements During Reactor Power Operation Above a Previously Attained Power Level Parameter Surveillance Frequency

1. Moisture Carryover Every 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> (Notes 1 and 2)

2. Main steam line pressure data Hourly when initially increasing power above a from strain gages previously attained power level AND At least once at every 40 MWt (nominal) power step above 100% OLTP (Note 3)

3. Main steam line data from At least once at every 40 MWt (nominal) power step accelerometers above 100% OLTP (Note 3)

AND Within one hour after achieving every 40 MWt (nominal) power step above 100% OLTP Notes to Table 1:

1. If a determination of moisture carryover cannot be made within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> of achieving an 80 MWt power plateau, an orderly power reduction shall be made within the subsequent 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> to a power level at which moisture carryover was previously determined to be acceptable.

For testing purposes, a power ascension step is defined as each power increment of 40 MWt, i.e., at thermal power levels of approximately 102.5%, 105%, 107.5%,

110%, 112.5%, 115%, 117.5%, and 120% OLTP. Power level plateaus are nominally every 80 MWt.

2. Provided thELt the Level 2 performance criteria in Table 2 are not exceeded, when steady state operation at a given power exceeds 168 consecutive hours, moisture carryover monitoring frequency may be reduced to once per week.

3. The strain gage surveillance shall be performed hourly when increasing power above a level at which data was previously obtained. The surveillance of both the strain gage data and MSL pressure data is also required to be performed once at each 40 MWt power step above 1593 MWt s.nd within one hour of achieving each 40 MWt step in power, i.e., at thermal power levels of approximately 102.5%, 105%, 107.5%, 110%, 112.5%, 115%, 117.5%, and 120% OLTP (i.e., 1593 MWt). If the surveillance is met at a given power level, additional surveillances do not need to be performed at a power level where data had previously been obtained.

If valid strain gage data cannot be recorded hourly or within one hour of initially reaching a 40 MWt power step from at least three of the four MSLs, an orderly power reduction shall be made to a lower power level at which data had previously been obtained. Any such power level reduction shall be completed within two hours of determining that valid data was not recorded.

Page 8 of 20 Rev. 3 Table 2 Steam Dryer Performance Criteria and Required Actions Performance Criteria Not to be Exceeded Required Actions if Performance Criteria Exceeded and Required Completion Times Level 2:

Moisture carryover exceeds 0.1%

OR Moisture carryover exceeds 0.1% and increases by

> 50% over the average of the three previous measurements taken at

> 1593 MWVt OR Pressure data exceed Level 2 Spectra'

1. Promptly suspend reactor power ascension until an engineering evaluation concludes that further power ascension is justified.

2. Before resuming reactor power ascension, the steam dryer performance data shall be reviewed as part of an engineering evaluation to assess whether further power ascension can be made without exceeding the Level 1 criteria.

+

Level 1:

Moisture ca ryover exceeds 0.35%

OR Pressure data exceed Level 1 Spectra'

1. Promptly initiate a reactor power reduction and achieve a previously acceptable power level (i.e., reduce power to a previous step level) within two hours, unless an engineering evaluation concludes that continued power operation or power ascension is acceptable.

2. Within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />, re-measure moisture carryover and perform an engineering evaluation of steam dryer structural integrity. If the results of the evaluation of steam dryer structural integrity do not support continued plant operation, the reactor shall be placed in a hot shutdown condition within the following 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />. If the results of the engineering evaluation support continued power operation, implement steps 3 and 4 below.

3. If the results of the engineering evaluation support continued power operation, reduce further power ascension step and plateau levels to nominal increases of 20 MWt and 40 MWt, respectively, for any additional power ascension.

4. Within 30 days, the transient pressure data shall be used to calculate the steam dryer fatigue usage to demonstrate that continued power operation is acceptable.

1 The EPU spectra shall be determined and documented in an engineering calculation or report.

Acceptable Level 2 spectra shall be based on maintaining 5 80% of the ASME allowable alternating stress (Sa) value at 10" cycles (i.e., 10.88 ksi). Acceptable Level 1 Spectra shall be based on maintaining the ASME Sa at 10" cycles (i.e., 13.6 ksi).

Page 9 of 20 Rev. 3 Table 3 Steam Dryer License Conditions License Condition Requirement Implementing Actions 3.M.1.a Entercly shall monitor hourly the 32 During initial power ascension above 1593 MWt, main steam line (MSL) strain gages data from at least 32 strain gages will be collected during power ascension above 1593 and evaluated by Entergy's power ascension test MWt for increasing pressure team to verify that acoustic signals indicative of fluctuations in the steam lines.

increasing pressure fluctuations in the steam lines are not challenging the steam dryer stress limit curve. Monitoring will be conducted hourly during any power ascension above a previously attained power level.

(Reference ERSTI-04-VY1-1409-000)

(Reference PCRS tracking item WT-VTY-2005-00000-01803) h.;

4 ~i~~

shl hol the faiiyfr2dh APhsetbihd test plat eau increments,,

HaI 80

>,d 0

n f

r w

~hor at15,10,ad 1%o.fapoximately_ 80Mt (corresponigto15 URP(~e,19 MWt), toclec 1% an 15 f 1593MWI Recor power4wl dafo te~2MSL stran' ggesnot eJinreased ab e th plta fo I

miUnimu ruid by LcneCniinof6hoursL,Durn th frt 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />' o sea y, 3UJ~

ondc pl ant isecis stteopera tion,e a

t6, f

e~Aach.plateau,,strain gage dat an Ikdow ns-,and evalut stait[be~olcedfo l avaiabl srigages, dr er prormance, biasedd on~

the (imu of3) ndeaatdodmnsrte data;_allprovide the evlaIo tjo" acetal sta re efrac Additionally te RCsffb facsimile o misuecrryover measurmentwilbmaea electonic ransmisso tthNRC ec lta n

vr 4husdrn oe proecmanaqge~r upon coqmpeto ofacnintsig At thp0 W patuhl th v4aluation; and shl not; pons egywlpodc pa-nt wlkows n ncaepoe.boe.ahhodinpetiosof patqUipmet incudng ipngAnd point.utl9hors

-after-teNCcmoet dniida ptentall vi rble ito the tra misio A

TP and ot er ln prcdrs Steramd uprorace w ai beeautdbsdo-heeat.

he. 24-hour perio adte9-Our peids a

overlap obnce, th nmitta is provie o h R

Te~a evlations "Of steam ryrpformance, bse on the

~dta cleted duig eachq ofth9 0 othere o

f,- or van us ~pngn Araneensh-ave been mad fl',or ~electronic b

eintdwbfe Upo

'I th fNC rjc Mngrcnrm ea X_________________

an efrac vlaiote9 or fhl

Page 10 of 20 Rev. 3 License Condition Requirement Implementing Actions time will comece Pwer~ wilntbJncreasd" aove, ech of he80MMt hol points untilth l<>

4: X df

t`hf expiration ~of ~the 96-huhod If duing te hod perodsor at any other tm,th NRC sf W.taffl~tJ r

ts n,

r carf icat ion ofn tee engin ering evaluations provided in ful illment coft tis r

enterigy Il promplyl arrangeo for Lsuh dicussions. Entiog will mntakn in aespow ascension cotp ntrol enter inud aing managem t overs ig ht, availabl o2417 on site duri power increasessv to pr eviously nt apower levels.

(Rvn eeferened RTh-L-vel 2 409-s000)

(Rfeece PR tracking item WT-VWTY-205 3.M.s.c If any frequency peak from the MSL The steam dryer stress limit curve provided strain gage data exceeds the limit herewith contains Level 1 and Level 2 criteria. If curve established by Entergy frequency peaks from MSL strain gage data exceed Nuclear Operations, trInc.

and either Level 1 or Level 2 criteria, promptraction will submitted to the NRC staff prior to be taken in response to the potential adverse flow operalion above OLTP, Entergy effects that might result. Similar actions will occur if Nuclear Operations, Inc. shall return moisture carryover is excessive and previously the facility to a power level at which established Level 1 or Level 2 criteria are the limit curve is not exceeded.

exceeded.

The Level 2 criteria represent a Entercry Nuclear Operations, Inc. conservative action level for evaluation and close shall resolve the uncertainties in the monitoring of steam dryer performance-not a limit.

steam dryer analysis, document the The Level 1 criteria represent analytical limits and continied structural integrity of the additional actions may be warranted.

steam

dryer, and provide that documentation to the NRC staff by If any frequency peak from the MSL strain gage facsimile or electronic transmission data exceeds the Level 1 steam dryer stress limit to the NRC project manager prior to curve, Entergy will reduce reactor power to a power further increases in reactor power.

level at which the limit curve is not exceeded.

(Reference ERSTI-04-VYr

-1409-000)

Prior to any further increase in power above the reduced power level, Entergy will (1) resolve the uncertainties in the steam dryer analysis, (2) evaluate and document the adequate structural integrity of the steam dryer, and (3) provide that documentation to the NRC staff. Any revision to the limit curve based on this evaluation will be provided to the NRC staff.

(Reference PCRS tracking item WT-VTY-2005-00000-01803)

Page 11 of 20 Rev. 3-License Condition Requirement Implementing Actions 3.M. 1.d In addition to evaluating the MSL Accelerometers mounted on MSL piping will be strain gage data, Entergy Nuclear monitored on an hourly basis during power Operations, Inc.

shall monitor ascension testing to identify if resonances are reactor pressure vessel water level increasing above nominal levels in proportion to instrumentation or MSL piping MSL strain gage data.

If abnormally increasing accelerometers on an hourly basis resonant frequencies are

detected, power during power ascension above ascension will be halted.

Prior to any further OLTP. If resonance frequencies are increase in power, Entergy will (1) evaluate and identified as increasing above document the adequate structural integrity of the nominal levels in proportion to strain steam dryer, and (2) provide that documentation to gage instrumentation data, Entergy the NRC staff.

Nuclear Operations, Inc. shall stop (Reference ERSTI-04-VY1-1409-000) power ascension, document the (Reference PCRS tracking item WT-VTY-2005-continued structural integrity of the 00000-01803) steam

dryer, and provide that documentation to the NRC staff by facsimile or electronic transmission to the NRC project manager prior to further increases in reactor power.

3.M.1.e Following start-up testing, Entergy After collecting strain gage data at approximately Nuclear Operations, Inc.

shall the EPU full power level, Entergy will resolve the resolve the uncertainties in the uncertainties in the steam dryer analysis and steam dryer analysis and provide provide documentation of the resolution to the NRC that resolution to the NRC staff by staff. If these actions cannot be achieved within 90 facsimile or electronic transmission days of issuance of the license amendment, reactor to the NRC project manager. If the power will be limited to 1593 MWt. This uncertainty uncertainties are not resolved within evaluation may be prepared and provided to the 90 days of issuance of the license NRC prior to reaching EPU full power levels amendment authorizing operation at associated with any proposed revision to the steam 1912

MWt, Entergy Nuclear dryer limit curve.

Operations, Inc. shall return the (Reference PCRS tracking item WT-VTY-2005-facility to OLTP.

00000-01803) rir oeatn a LP, COMPLETE T

enhce perormance..' and

.U : vEnt'ersy

Nuclea-r' sOp'-erations, nc.' improve the

,accurac of the steam d

sh i

lional i

measuremnt system Entergy has Vinstaled 48

,gages on themain s eam pipin aigages on MS p

shall enhance the data acquisition minimum of 32 operable strain gages during power sse ino toreduce' the'acnintsig The daaaqiitinyse

'. W' t A itn eal:'r mesremen uncrtaint (DS as upgradeddtoredce he ncrtant asoitdwth the a~coustic circuit associtdWith the ACM m::

rodeiefrnce ntergy"VYNPS `Temporary lri M brven tiOMPLE Ap of te e uatipom are idntifid" tha't challng fthelmta 63~

neg emn akeepoe cuv ug powe ascensio ne

rviin, ofgythe Aousi ici oe.I

Page 12 of 20 Rev. 3 License Condition Requirement Implementing Actions abov LT, Entergy Nuti wit tbenchmarking the` newACM perations, inc.

shall' evaluate a frequency--specific assessment-of the ACM snteam ryer uladsrand re-establishc hnefrtaitw poerfre and is con estaine th mt ll ure basued o the ne eac VYCr fRevi l.

strain gagesdata, and shabl per form (e

e facilp4h-VY1-149r0trs a frequeny-pcii aseseto Rfrnce VYC_3061 Rev. 1 signa frec uency 3.M.2.c After reaching 120%

of OLTP, After collecting strain gage data at approximately Entergy Nuclear Operations, Inc. the EPU full power level, Entergy will establish the shall obtain measurements from the steam dryer flow-induced vibration load fatigue MSL strain gages and establish the margi n for the facility, update the steam dryer stress steam dryer flow-induced vibration report, and re-establish the stress limit curve with load fatigue margin for the facility, the updated ACM load definition and revised update the steam dryer stress instrument uncertainty.

This information will be report, and re-establish the steam included in the report to the NRC staff being made dryer monitoring plan (SDMP) limit in accordance with License Condition 3.M.1.e.

curve with the updated ACM load (Reference PCRS tracking item WT-VTY-2006-definit on and revised instrument 00000-00249) uncertainty, which will be provided to the NRC staff.

3.M.2.d During power ascension above MPLEE -As part of the vevaluation performed' OLP i nenierigealain t173~

ntergy,~,Vermont:1 Yanke comple ted, i UTeua~t Y

Wipe isrqiedi

'codanewth reisin 'to the VY Stea'm. Dryer,model used in -the' MFE rgy N ear Oper

, Fi menMd

(

.Adqditional anralysis f n. a perfom hea p

structuraan c

the FEMise Soutpupt pvwas perorme tmo asssshen analy revise to adress frequencyt fee cye unertrante Th acresul ofthis ucranies-~~

up to+/-0% adasesent aecniednCalcltion 1VYC-~

asuota ea epne thatfal 300,Revs 1.rdd Jh within' tis uncertinty ban ar (RfrncAlTl0-Y 14900 3.M.2.e Entercgy Nuclear Operations, Inc. The revised SDMP provides long-term monitoring of shall revise the SDMP to reflect steam dryer performance in accordance with GE long-term monitoring of plant SIL 644 Rev. 1.

parameters potentially indicative of (Reference PCRS tracking item WT-VTY-2006-steam dryer failure; to reflect 00000-00250) consistency of the facility's steam dryer inspection program with COMPLETE - The SDMP and the PATP identify the General Electric Services NRC Project Manager for the VYNPS EPU as the Information Letter 644, Revision 1; point of contact for providing SDMP information and to identify the NRC Project during power ascension.

Manager for the facility as the point (Reference ERSTI-04-VY1-1409-000) of contact for providing SDMP information during power ascension.

COMPLETE - For moisture carryover, procedures OP-0631 and ON-3178 provide for long-term monitoring and controls.

Page 13 of 20 Rev. 3 License Condition Requirement Implementing Actions 3.M.2.f Entercly Nuclear Operations, Inc. The final EPU steam dryer load definition will be shall submit the final extended included in the report provided to the NRC staff in power uprate (EPU) steam dryer accordance with License Conditions 3.M.l.e. and load definition for the facility to the 3.M.2.c.

NRC upon completion of the power (Reference PCRS tracking item WT-VTY-2006-ascension test program.

00000-00251) 3 M2.g JEnitergy, Nuclaea Operations,!1 Inc.. COPET.

Etrg.ete BY.6.9.owad shl umtte fojnue he~.`Fl V-related ;"'portions--,d the EL oe Vibra ti)nrelatdprin fteEU asc'ensio test procedtoreW',

toteNC Rfrence statu test procede to th

NSRC, b

RS6-0VY49Q incluin methodolgy, forudtn th-ii ure 7

t nta power paigthe,,, seam d ascen iona bove, OLP tess lmtcreis as. foWs:

Prerequiite Gnrte eporreovn uncertaintii the stAm dryeanlss

-tdata frome32tstrain 1." Collect ~representativel*aa o Z

' i gages 2.,at eight MSL locations.j 2 Using'~a pla~nt-spbecdific ACM Analyze sraini gag attodtrine steam dryer lod Input ACM oads int a finit elemen model tI deerin dyers sresses>,

4.Prorm,,an updated ucranyvauatiom.

5Generate eie ta drye sress'limtit (Re erencePCRS't'rac6king ite WTVTY-77 6

3..() Eteg ht rep th`EUCOMVPLETE ~l-The steam dryer stress Imtcret strss imi cuve o b aplie fo duingpowr acenionis rovide hrewsith.

c,&The evaruting, sprd 0

steam drer hlimi cuv a

vlp d onrte brasis o reerne inote EP PTP.

(RfeeceEST-4eY-10-0s 3.Mm3(bu Entr shall pre arethPU COMPLETE, -or aSpectifricsholdprovinsad duainar stru etpoeue toincue specified nithe PTP ouain duringcEPUopower s-b,,Etaru etpoeuet nl hMldEoits are specified h~pinthe PaTPdrainsae acivities tbeaomUsr d uin Reeence 1l0-Y11090O

__ ho d oi ts

Page 14 of 20 Rev. 3 License Condition Requirement Implementing Actions 3.Md)P Entergy shall prepare the EP SCOMPLETE - Pl antparameters to be monitored'are

Ent:r stru es rcduret nld pcfe in'Attachmenht 9`4 to tePATP 3..() Ene" hllpeaethe EP.U COMPLETE npciosadwalkownstob satuptst.,,procedure to inclde codced for_ s"afewaeadcondensat

• inspectins and.wakdowns to be systems anrd cmponents during hold' points are copoens uring the3 hold points.

iVE,g-i

-.3f)

E ter yi sa prepar t

iEU C,

-to be used to tre plnti struptest proc seduree to icue prameer are spcfe inAtacmnt 9 to the p

metod t beusd o ten pant PAT pamt' rer.

(Reference ESTI -VY

-14000) 3.M.3(g Enteri shallI prepare;, the -EPUih COMPLETE -Acceptance criteria for"onitoring u

procre ie ding lan pmet and sconducting the aceineciterafrmnitrn akdowns:and ingspecinaeseified in reo,-nUeeTO me te t

t ar tre n the s-..

talil; t i,,,p >rp

,, u, ram,j t'

_Ji i.

i, i..Jn,,ft:

i:'"

Wii'X.

a

<'i'5";.

atiost etkn facpac (RefeenceERTI-04-VY nc'1t 409"000 crtraar o satified aw.(i neply sall peaeteEUCMLETkdeiiato ftecopeino vriciooftecmltooflcneaedetapiaonn andall spplemnt application and all supple ments o peiiedinthPTP the r

a nplicatoin supportm ofiAnl thTRfrncIPT-4VY-4900 e

at pertaining to the seiai dr r-.

t~:X~f D D.

f.

7

Page 15 of 20 Rev. 3 3.M.4 When operating above OLTP, the operating limits, required actions, and surveillances specified in the SDMP shall be met. The following key attributes of the SDMP shall not be made less restrictive without prior NRC approval:

a. During initial power ascension testing above OLTP, each test plateau increment shall be approKimately 80 MWt;

b. Level 1 performance criteria; and

c. The rriethodology for establishing the stress spectra used for the Level 1 and Level 2 performance criteria.

Changes to other aspects of the SDMP may be made in accordance with the guidance of NEI 99-04.

These restrictions are provided in the the SDMP.

(Reference ERSTI-04-VY1-1409-000)

PATP and/or 3.M.5 During each of the three scheduled refueling outages (beginning with the spring 2007 refueling outage),

a visual inspection shall be conducted of all accessible, susceptible locations of the steam dryer, including flaws left "as is" and modifications.

The VYNPS steam dryer will be inspected during the refueling outages scheduled for the Spring 2007, Fall 2008, and Spring 2010. The inspections conducted after power uprate implementation will be comparable to the inspections conducted during the Spring 2004 and Fall 2005 refueling outages and will be in accordance with the guidance in SIL 644, Rev. 1.

(Reference PCRS tracking item WT-VTY-2006-00000-00253)

(Reference PCRS tracking item WT-VTY-2006-00000-00254)

(Reference PCRS tracking item WT-VTY-2006-00000-00255)

Page 16 of 20 Rev. 3 3.M.6 The results of the visual inspections of the steam dryer conducted during the three scheduled refueling outages (beginning with the spring 2007 refueling outage) shall be reported to the NRC staff within 60 days following startup from the respective refueling outage. The results of the SDMP shall be submitted to the NRC staff in a report vwithin 60 days following the completion of all EPU power ascension testing.

The VYNPS steam dryer will be inspected during the refueling outages scheduled for the Spring 2007, Fall 2008, and Spring 2010. The inspections conducted after power uprate implementation will be comparable to the inspections conducted during the Spring 2004 and Fall 2005 refueling outages and will be in accordance with the guidance in SIL 644, Rev. 1. The results will be documented in a report and submitted to the NRC within 60 days following completion of all EPU power ascension testing.

(Reference PCRS tracking item WT-VTY-2006-00000-00256)

(Reference PCRS tracking item WT-VTY-2006-00000-00257)

(Reference PCRS tracking item WT-VTY-2006-00000-00258) 4 4

3.M.7 The requirements of paragraph 3.M.4 above for meeting the SDMP shall be implemented upon issuance of the EPU license amendment and shall continue until the completion of one full operating cycle at EPU. If an unacceptable structural flaw (due to fatigue) is detected during the subsequent visual inspection of the steam dryer, the requirements of paragraph 4 shall extend another full operating cycle until the visual inspection standard of no new flaws/flaw growth based on visual inspection is satisfied.

When operating above 1593 MWt, the operating limits, required actions, and surveillances specified in the SDMP will be met. Those key attributes of the SDMP specified in License Condition 3.M.4 will not be made less restrictive without prior NRC approval.

(Reference PCRS tracking item WT-VTY-2006-00000-00259) 3.M.8 This license condition shall expire (Reference PCRS tracking item WT-VTY-2006-upon satisfaction of the 00000-00260) requirements in paragraphs 5, 6, and 7 provided that a visual inspection of the steam dryer does not reveal any new unacceptable flaw or unacceptable flaw growth that is die to fatigue.

Page 17 of 20 Rev. 3 1.OE+00 1.OE-01 1.OE-02 X

1.OE-03 1.OE-04 1.OE-05 1.OE-06 0

50 100 150 200 Frequency, Hz 250 LC2 AveMSL_AUpper Fiaure 1: Steam Drver Stress Limit

-LC1lAve-MSL A-Upper Curve - MSL 'A' Upper 1.OE+O0 I.OE-01 I.OE-02 9

1.OE-03 1.OE-04 1.OE-05 1.OE-06 0

50 100 150 200 Frequency, Hz 250

-LC2-Ave-MSL-A-Lower

-LCl-Ave-MSL A Lower Figure 2: Steam Dryer Stress Limit Curve - MSL 'A' Lower G'OP

Page 18 of 20 Rev. 3 1.OE+00 1.OE-01 1.OE-02 t

1.0E-03 1.OE-04 1.OE-05 1.OE-06 0

50 100 150 200 Frequency, Hz

-LC2_AveMSLBUpper

-LClAve MSLB-Upper Figure 3: Steam Dryer Stress Limit Curve - MSL 'B' Upper 250 1.OE+00 1.OE-01 1.OE-02 1

1.OE-03 1.OE-04 1.OE-05 1.OE-06 CS7

50 100 150 200 Frequency, Hz LC2 Ave-MSLB Lower LC1Ave MSLB Lower Figure 4: Steam Dryer Stress Limit Curve - MSL 'B' Lower 250

Page 19 of 20 Rev. 3 1.E+00 1.E-01 1.E-02 I

I.E-03 1.E-04 I.E-05 1.E-06 C

1.OE+00 1.OE-01 1.OE-02 I

1.OE-03 1.OE-04 1.OE-05 1.OE-06 I

50 100 Frequency, Hz

-LC2.AveMSLCUpper Ficiure 5: Steam Drver Stress Limit 150 200 250

-LlAveMSL.C-Upper Curve - MSL 'C' UDDer 0

50 100 150 200 250 Frequency, Hz LC2 Ave MSLC Lower LC1_Ave MSLC-Lower Figure 6: Steam Dryer Stress Limit Curve - MSL 'C' Lower 0Co

Page 20 of 20 Rev. 3 1.OE+00 1.QE-01 1.0E-02 1.OE-03 I.

I 1.OE-05 1.OE-06 0

50 100 150 200 250 Frequency; Hz LC2_AveMSL D Upper

-LCW1AveMSL DUpper Figure 7: Steam Dryer Stress Limit Curve - MSL 'D' Upper 1.OE+OO 1.OE-01 1.OE-02 1.OE-03 I.OE-04 I.OE-05 1.OE-06 0

50 100 150 200 250 Frequency, Hz LC2_AveMSL D Lower

-LC1 Ave MSLDLower Figure 8: Steam Dryer Stress Limit Curve - MSL 'D' Lower C.,

BVY 06-042 Vermont Yankee Nuclear Power Station Basis for Compliance with License Condition 3.M.4

Page 1 of 3 Bases for Compliance with License Condition 3.M.4

References:

1. ERSTI-04-VYl-1409-000, "Power Ascension Test Procedure for Extended Power Conditions 1593 to 1912 MWt (PATP)

2. Vermont Yankee Steam Dryer Monitoring Plan, Revision 3

Purpose:

The Vermont Yankee Steam Dryer Monitoring Plan, Reference 2, incorporates a revision to the Level 1 and Level 2 Limit Curves based on use of the existing Finite Element Model results using 1791 MWt data and a reduction of the limit factor based on the calculated increased in dryer stress intensity based on the 1872 MWt Strain Gage data.

This documEnt assesses compliance of Revision 3 to the Vermont Yankee Steam Dryer Monitoring Plan with Vermont Yankee (VY) License Condition 3.M.4.

Discussion:

On April 22, 2006 VY raised reactor power from 1792 MWt to 1832 MWt. This was followed on April 28, 2006 with power ascension to 1872 MWt. At the 1872 MWt power level, the upper and lower sets of strain gages on the 'A' main steam line provided indications at 143.5 Hz that exceeded the Level 2 Acceptance Criteria of the Steam Dryer Monitcring Plan (SDMP, Rev. 2).

VY entered the event into the plant corrective action program and performed an engineering evaluation that concluded that continuous operation at the existing power level (1872 MWt) would not challenge steam dryer integrity.

Entergy performed a review of the 1872 MWt data based on the results of the ANSYS Finite Element Model (FEM) performed at 1791 MWt. This evaluation is contained in VYC-3001, Revision 2, Minor Calculation Change (MCC) 2. This evaluation shows that from 1791 MWt to 1872 MWt the stress on the steam dryer limiting component (gusset shoe) has increased from 2688 psi to 3599 psi. This new stress result from the Acoustic Circuit Model (ACM) method is combined with the Computational Fluid Dynamics (CFD)

Stress (599 psi) and results in a conservative reduction in the Level 1 limit factor from 3.53 to 2.64.

Entergy also used the FEM results at 1791 MWt and the strain gage data at 1872 MWt to project the estimated total stress at full power (1912 MWt). The combined ACM and CFD stress at 1912 is estimated to be 4050 psi with 236 percent margin to the 13,600psi ASME limit.

The use of the strain gage data from 1872 MWt in comparison with the 1791 MWt ACM/FEM results and generation of revised steam dryer limit curves has been assessed against the requirements of License Condition 3.M.4 which states:

"When operating above OLTP, the operating limits, required actions, and surveillances specified in the SDMP shall be met. The following key attributes of the SDMP shall not be made less restrictive without prior NRC approval:

Page 2 of 3

a. Durir~g initial power ascension testing above OLTP, each test plateau increment shall be approximately 80 MWt;

b. Leve! I performance criteria; and

c. The methodology for establishing the stress spectra used for the Level I and Level1 2 performance criteria.

Charges to other aspects of the SDMP may be made in accordance with the guidance of NEI 99-04."

As described above, License Condition 3.M.4 specifies those attributes of the approach to steam dryer monitoring that require NRC approval prior to being made less restrictive.

As addressed below, VY concludes that the key attributes have NOT been made less restricted and, therefore, the proposed model and limit curve changes do NOT require prior NRC approval.

The following changes have been incorporated into the VY approach to steam dryer monitoring:

1. An updated Level 1 Limit Curve representing a conservative reduction of the Level 1 Limit Factor from 3.53 to 2.64 based on the values obtained in the 1872 MWt FEM/Strain Gage evaluation.

The methodology for calculating the proposed limit curve factors at 1872 MWt is unchanged from the methodology employed for calculating the limit curve factors at the 1791 MWt power ascension plateau.

2. The FEM/Strain Gage Evaluation is based on using the results of the FEM performed using inputs from the last ACM runs (at the power ascension plateau of 1791 MWt) and, after determining the sensitivity of the FEM for each key in-plant acoustic frequency, calculating the change in the FEM results for the given Strain Gage changes. No new methodologies are employed to calculate these results. This technique for calculating the governing component stress intensity at 1871 MWt continues to rely on the governing principal of linear stress analysis in that a structure will experience an increase in stress intensity linearly with an increase in applied load.

This revision of the SDMP was evaluated against the criteria in License Condition 3.M.4 to determine if NRC approval is required as summarized below:

a. This revision proposes no change in the test plateau increments from those specified in the criteria.

b. The Level 1 performance criteria is defined as a limit curve for strain gage results that represents a stress on the dryer equal to the ASME Design Limit of 13.6 ksi minus the calculated total model and measurement uncertainty. The updated limit curves still represent the ASME criteria minus the calculated uncertainty.

c. The methodology for establishing stress spectra for the Level 1 and Level 2 criteria is not altered by this change.

Page 3 of 3 As required by License Condition 3.M the dryer component stress intensities are generated from the FEM.

Post-processing of the FEM generates the relative contribution of the significant in-plant forcing function frequencies.

The changes in main steam line strain gage readings at these frequencies are then input into the calculation to develop a new resultant stress. This revised, conservatively determined stress is then used to generate revised Level 1 and Level 2 limit factors and maintains the same ACM/FEM linearity and employs the same uncertainty values.

The above changes were evaluated using the guidance provided in NEI 99-04.

==

Conclusion:==

1. Basei on the analysis performed using VYNPS Strain Gage data taken at the 1872 MWt plateau and employing the use of the frequency sensitivities generated by the ANSYS FEM there is significant margin to the ASME fatigue limit and the final 40 MWt power ascension is not expected to result in challenge to the Level 1 Limit Curve.

2. The SDMP has not been made less restrictive by the changes made to the generation of the Level 1 Limit Factor based on the FEM/Strain Gage evaluation.

Therefore, prior NRC approval is not required to implement these changes.

Preparer: Craig Nichols

/7 6

5

/

Name Signature

'D are Reviewer: James Callaghan r Name Si rq\\,

Date ADDrover: John Drevfuss L(,K7IQ

\\