BVY 06-031, Revision 1 to Steam Dryer Monitoring Plan

Revision 1 to Steam Dryer Monitoring Plan

ML060930689
Person / Time
Site:	Vermont Yankee
Issue date:	03/26/2006
From:	Rademacher N Entergy Nuclear Northeast, Entergy Nuclear Operations
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
BVY 06-031, TAC MC0761
Download: ML060930689 (27)

Text

Entergy Nuclear Northeast Entergy Nuclear Operations, Inc.

Vermont Yankee P.O. Box 0500 I.l v2J(2atI-r,185 Old Ferry Road J I t irgy Brattleboro, VT 05302.0500 Tel 802 257 271 March 26, 2006 Docket No. 50-271 BVY 06-031 TAC No. MC0761 ATTN: Document Control Desk U.S. Nuclear Regulatory Commission Washington, DC 20555-0001

Subject:

Vermont Yankee Nuclear Power Station Revision 1 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, Extended Power Uprate - Regulatory Commitment Information Regarding Steam Dryer Monitoring and FIV Effects,"

BVY 06-01 9, February 26, 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 1) 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 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 Extended Power Uprate conditions. Attachment 2 provides the justification, consistent with License Condition 3.M.4 for why this change does not require prior NRC approval.

Ail

BVY 06-031 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, Norman L. Rademacher Director Nuclear Safety Assurance 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 Allendale Road King of Prussia, PA 19406-1415 Mr. Richard B. Ennis, Project Manager Project Directorate I Division of Ucensing Project Management Office of Nuclear Reactor Regulation U.S. Nuclear Regulatory Commission Mail Stop 08B1 Washington, 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 06-031 Docket No. 50-271 Attachment 1 Vermont Yankee Nuclear Power Station Steam Dryer Monitoring Plan Revision 1 Total number of pages in Attachment 1 (excluding this cover sheet) is 20.

Entergy Vermont Yankee Steam Dryer Monitoring Plan

• Revision 1 March 25, 2006 Prepared BIV 131/9?- /06 J -

Caig J. Nichols Date Reviewed By I c -d Aes Calkgjtan Date Approved B l-IX-25^C Joh D Ss U Date

Page 1 of 19 Rev. 1 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 through the measurement of a combination of plant parameters.

Scope The SDMP is primarily 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. Power 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 conditions.

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 19 Rev. 1 Power Ascension VYNPS procedure ERSTI-04-VY1-1409-000, "Power Ascension Test Procedure for Extended Power Conditions 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 MWtthr;

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

3. Four hour 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 for 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 conditions.

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

• Main Steam Line Strain Gages Entergy has installed 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 and a more conservative representation of the peak frequencies.

Page 3 of 19 Rev. 1

• 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.

• 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 38%. This value is used in the determination 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:

Maximum Uncertainty of the ACA Methodology 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: 15%

SG and DAS ability to measure pressure in Pipe 11%

Combined Uncertainty by Square Root Sum of the Squares 38%

• 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 RMS values of in-plant data with a-standard deviation of 82%. Therefore a --

conservative estimate of uncertainty is 118% - 82% = +38%. 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%. Therefore the CFD frequency uncertainty is determined to be 4%. The total CFD uncertainty; uncCFD= sqrt(15A2 + 4A2) = 16%.

Page 4 of 19 Rev. 1 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.

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 Notifications

• 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, "Eniergy"*iH'prtovide 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. In addition the final full EPU power performance criteria spectra (i.e., steam dryer stress limit curve) will be 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

Page 5 of 19 Rev. 1 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 Monitorina 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 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 monitoring 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 6 of 19 Rev. 1 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 that 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 and 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 7 of 19 Rev. 1 Table 2 Steam Dryer Performance Criteria and Required Actions Performance Criteria Not to be Required Actions if Performance Criteria Exceeded and Required Exceeded Completion Times Level 2: 1. Promptly suspend reactor power ascension until an engineering evaluation concludes that further power ascension is justified.

• Moisture carryover exceeds 0.1% 2. Before resuming reactor power ascension, the steam dryer OR performance data shall be reviewed as part of an engineering evaluation to assess whether further power ascension can be made

• Moisture carryover exceeds without exceeding the Level 1 criteria.

0.1% and increases by

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

> 1593 MWt OR

• Pressure data exceed Level 2 Spectral Level 1: 1. Promptly initiate a reactor power reduction and achieve a previously acceptable power level (i.e., reduce power to a previous step level)

• Moisture carryover exceeds within two hours, unless an engineering evaluation concludes that 0.35% continued power operation or power ascension is acceptable.

OR

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

• Pressure data exceed Level engineering evaluation of steam dryer structural integrity. If the 1 Spectra1 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.

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

Acceptable Level 2 spectra shall be based on maintaining < 80% of the ASME allowable alternating stress (Sa) value at 1011 cycles (i.e., 10.88 ksi). Acceptable Level 1 Spectra shall be based on maintaining the ASME Sa at 1011 cycles (i.e., 13.6 ksi).

Page 8 of 19 Rev. 1 Table 3 Steam Dryer License Conditions License Condition Requirement Implementing Actions 3.M.1.a Entergy 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) 3.M.1 .b Entergy shall hold the facility for 24 The PATP has established test plateau increments hours at 105%, 110%, and 115% of of approximately 80 MWt (corresponding to 105%,

OLTP (i.e., 1593 MWt) to collect 110%, and 115% of 1593 MWt). Reactor power will data from the 32 MSL strain gages not be increased above the plateau for a minimum required by License Condition of 96 hours0.00111 days <br />0.0267 hours <br />1.587302e-4 weeks <br />3.6528e-5 months <br />. During the first 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> of steady 3.M.1.a, conduct plant inspections state operation at each plateau, strain gage data and walkdowns, and evaluate steam will be collected from all available strain gages dryer performance based on these (minimum of 32) and evaluated to demonstrate data; shall provide the evaluation to acceptable steam dryer performance. Additionally, the NRC staff by facsimile or moisture carryover measurements will be made at electronic transmission to the NRC each plateau and every 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> during power project manager upon completion of ascension testing. At the 80 MWt plateau hold the evaluation; and shall not points, Entergy will conduct plant walkdowns and increase power above each hold inspections of plant equipment, including piping and point until 96 hours0.00111 days <br />0.0267 hours <br />1.587302e-4 weeks <br />3.6528e-5 months <br /> after the NRC components identified as potentially vulnerable to project manager confirms receipt of flow-induced vibration (FIV) in accordance with the the transmission. PATP and other plant procedures. Steam dryer performance will be evaluated based on these data.

The 24-hour period and the 96-hour period may overlap once the transmittal is provided to the NRC staff.

The evaluations of steam dryer performance, based on the data collected during each of the 80 MWt plateaus, as well as the results of walkdowns and other measurements of FIV for various piping and plant components, will be provided to the NRC staff.

Arrangements have been made for electronic transmission through email and/or uploading to a designated website. Upon the NRC Project Manager confirming receipt of the steam dryer data and Derformance evaluation, the 96 hours0.00111 days <br />0.0267 hours <br />1.587302e-4 weeks <br />3.6528e-5 months <br /> of hold

Page 9 of 19 Rev. 1 License Condition Requirement Implementing Actions time will commence. Power will not be increased above each of the 80 MWt hold points until the expiration of the 96-hour hold.

If during the hold periods, or at any other time, the NRC staff requests a discussion or requires clarification of the engineering evaluations provided in fulfillment of this requirement, Entergy will promptly arrange for such discussions Entergy will maintain a power ascension control center, including management oversight, available 24/7 on-site during power increases to previously unattained power levels.

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

(Reference PCRS tracking item WT-VTY-2005-00000-01803) 3.M.1.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, Inc. and either Level 1 or Level 2 criteria, prompt action will submitted to the NRC staff prior to be taken in response to the potential adverse flow operation 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 Entergy 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 continued 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-VY1-1409-000)

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 10 of 19 Rev.. 1 License Condition Requirement Implementing Actions 3.M.l.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)

.1M.2.a ror to operation 'above OLTP, OMPLETE - To -enhance; performance and ntergy Nuclear Operations, Inc. prove the accuracy of the steam dryer hall install -32 additional strain easurement system, Entergy has installed 48 ages on the main steam piping and train gages onwMSL piping-and witll maintain a hall enhance' the Idata acquisition inimum of -32 operable strain gages during power ystem in order to reduce- the scension testing. The data acquisition system easurement -uncertainty DAS) was. upgraded to reduce the uncertainty ssociated with 'the acoustic circuit ssociated with the ACM.'

odel {ACM). Reference Entergy VYNPS T1empary Alteration 0A-20015 R1)

O.M.2.b n the event- that acoustic -signals POMPLETE As part of the evaluation performed ire identified that'challenge the limit at 1673MWt Entergy Vermont Yankee employed a

_ure during power ascension Hew revision of the Acoustic Circuit Model. In

Page 11 of 19

.Rev. 1 License Condition Requirement Implementing Actions bove OLTP, Entergy 'NKuclear Issociation with the benchmarking of the new ACM perations, Inc. shall evalu frequency specific assessment of the ACM team dryer loads and re-establish uncertainty was performed and is contained in e limit curve based obnthe heneW VacuationYC-3001, Rev. 1 rain gage data, and shall pedorn fReferenceRERSTI-O4-V1-1409I-O) frequency-specific assessment 0! LRtferenceYC-3001 RYvJ V)

MCM uncertainty -at, thse ignal frequency._

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 margin 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-definition and revised instrument 00000-00249) uncertainty, which will be provided to the NRC staff.

3.M.2.d uring power ascension abovo OMPLETE - As part of the evaluation performed LTP, if an engineering evaluatior t 1673MWt Entergy Vermont Yankee completed required in accordance with the evisions to the VY Steam Dryer model used in the DMP, Entergy Nuclear Operations, mite Element-Model (FEM). Additional analysis' of nc. shall perform the structural output was performed to assess th.

nalysis to address '0Jfrequency equency uncertainties. The results of this ncertainties up to +/--1 0%. and ssessment are Galcu-lati- Vcontainedkin ssure that peak responses thatifall 001, Rev. 1.

ithin this,,uncertainty and, are tRefer-nce PERUS14-Vy)09O0

____ ____ ddressed.

3.M.2.e Entergy 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 MUlPLETEThgiainthetPATP identitfy' General Electric Services RC Project Manager for the VYNPS ,EPUt as the Information Letter 644, Revision 1; mint of contact for providing, SDMP information and to identify the NRC Project Juring power ascension Manager for the facility as the point 'Reference IRSTI-04-VYf1O9-bOO) of contact for providing SDMP , - a., .-

information during power ascension. %OMPLETE- Fig moisture carryover, procedures DP-0631 and ON-3178 provide for, long-term nonitoring and controls.

Page 12 of 19 Rev. .1 License Condition Requirement Implementing Actions 3.M.2.f Entergy 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.1.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)

-M. g ntergy Nuclear OperationsMInc. ,OPLETE - Entergy letter :V06-019 forwards hall, submit the flow-induced he FlV-related portions of the EP-.R power ibration related portions of the EPU scension test procedure to the NRC., (Reference tartup test procedure to the NRC, RSTl-94-Yi1-14Q 9-0P) cluding methodology' forupdating he limit curve, prior toTnitiaI p0owe-da o0y for estear sensionabove OLTP. - e;liAmit curve is Wasfolows, Prrqisite:, Generate report resolvng

_pcertainties intIe stpam,danlysis.

ht eight MSL locatons.

n7sing a plant-specific ACM_,analye_ srngage jata to determine steam dryer loads.

~Input ACM loads into a finite element iimode to ietermine dryer stresses.'

.Perfom an updated u nevaluation.-

Lo.Generate revised steamdrypustre sslimit jurve(s).

[Ftefrence POR'S takn t :2Q061 Ip0000252)

O.O.?3(a) :ntergy, shallo prepare,'the EPU OMPLETE The steam dryer stress limit curve to test procedure to include-the ptartup e applied for evaluating steam- dryer performance stress limit curve- to' be applied, for uring power ascension, is provided herewith. The valuating , steam drye mit curve' was developed on the basis of performance. Iculation VYC-3001, which incorporated by eference into the EPU PATP.

ReferenceERSTI-04-VY1 -14,, 06) p.M.3(b) ntergy 'shall prepare ' 'the', EPU JOMPLETE - Specfic hold pqpintsand ,durations are startup test procedure to- include gpecified in the PATP.

Qpecific hold points and their Reference ERSTI-04-VY1 -1409:000) uration during EPU- power

.scension.

3.M.3(c) gntergy shall prepare the EPU vOMPLETE - Activities to be accomplished during Startup test procedure 'to 'include old points are specified in the PATP.

activities to be accomplished duing Reference ERSTI-04-VYI-1409-O00) hold points

Page 13 of 19 Rev. 1 License Condition Requirement Implementing Actions

-,.M,*3) n'tergy shall prepare the EPU ,OMPLETE - Plant parameters to be monitored are

,tartup test' procedure Idc inciud, pecified in Attachment 9.to the PATP.

,taat pairaeterpsto bempnitored. IReference ER!STI-04-yY-14Q0- 000)

-.N¶3, ntergy' shall; prepare. the EPU ,OMPLETE - Inspections and walkdowns to, be

,tartup test procedure, to indlude londucted for steamr feedwater, and condensate nspections and. walkdoWns ta, be'ystems and components during holdpoints are Sonducted for steam, feedwater, pecified in Attachment 9 to the PATP.

xnd condensate systems and ReferencerERSTI-Q4-VrY1-1409-000) o~mpqonents during theholdqSipts

>MAf) bntergy shalliprepare the` EPU ,OMPLETE - Methods to beo used-to trend plant

,tartup test procedure to incIude arameters are specified, in, Attachment, 9 to the nethods; to .e Xus~ed ottdi -plant .ATP arameters. [Referenc 0 -1.409-00)

IRS

~.M..(. ntergy, shall' prepare: the EPU, OMPLETE - Acceptance criteria- for monitoring

.tartup. test procedurqa ' tQ. include nd. trnding plant parameters, and conducting the rcceptance criteria, for, monitoring alkdowns and inspections are specified in knd trending plant parameters, and ttachment 9 tojthe PAJP.( efqereceERSTI-044-Wonducting th, waldkow nd 1-1409-000 nspections.

r.i3(h) ',shall prepare' Entergy ath-EPL ,QMPLETE - Actions to be taken:if acceptance startup test, procedure to Include iriteria are not satisfied are specified in theATPA Ictions to be taken if, accptance Leferencie ESW1-04-, 1,-000)

Writeria are not satisfied,

'ntergyshall prepare' the EPU OMPLETE - Verification, of .the completion of tartup test procedure to include ommitments and planned, actions specified in the erification of the completion of cense amendment application and all supplements ommitments.- and planned. actions othe application in support of the EPU license pecified in the license amendment nendment request peritaining, to the steqam drier is pplication and all supplements to ecified in the PATP.

he application in support ofi the ERS PU license amendment req66est ertaining to the steam drye,

Page 14 of 19 Rev. 1 3.M.4 When operating above OLTP, the These restrictions are provided in the PATP and/or operating limits, required actions, the SDMP.

and surveillances specified in the (Reference ERSTI-04-W1V-1409-000)

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 approximately 80 MWt;

b. Level 1 performance criteria; and

c. The methodology 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 auidance of NEI 99-04.

3.M.5 During each of the three scheduled The VYNPS steam dryer will be inspected during refueling outages (beginning with the refueling outages scheduled for the Spring the spring 2007 refueling outage), 2007, Fall 2008, and Spring 2010. The inspections a visual inspection shall be conducted after power uprate implementation will conducted of all accessible, be comparable to the inspections conducted during susceptible locations of the steam the Spring 2004 and Fall 2005 refueling outages dryer, including flaws left 'as is' and will be in accordance with the guidance in SIL and modifications. 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 15 of 19 Rev. I The results of the visual The VYNPS steam dryer will be inspected during 3.M.6 inspections of the steam dryer the refueling outages scheduled for the Spring conducted during the three 2007, Fall 2008, and Spring 2010. The inspections scheduled refueling outages conducted after power uprate implementation will (beginning with the spring 2007 be comparable to the inspections conducted during refueling outage) shall be reported the Spring 2004 and Fall 2005 refueling outages to the NRC staff within 60 days and will be in accordance with the guidance in SIL following startup from the 644, Rev. 1. The results will be documented in a respective refueling outage. The report and submitted to the NRC within 60 days results of the SDMP shall be following completion of all EPU power ascension submitted to the NRC staff in a testing.

report within 60 days following the (Reference PCRS tracking item WT-VTY-2006-completion of all EPU power 00000-00256) ascension testing. (Reference PCRS tracking item WT-VTY-2006-00000-00257)

(Reference PCRS tracking item WT-VTY-2006-00000-00258) 3.M.7 The requirements of paragraph When operating above 1593 MWt, the operating 3.M.4 above for meeting the SDMP limits, required actions, and surveillances specified shall be implemented upon in the SDMP will be met. Those key attributes of issuance of the EPU license the SDMP specified in License Condition 3.M.4 will amendment and shall continue not be made less restrictive without prior NRC until the completion of one full approval.

operating cycle at EPU. If an (Reference PCRS tracking item WT-VTY-2006-unacceptable structural flaw (due 00000-00259) 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.

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 due to fatigue.

Page 16 of 19 Rev. I MSL A Upper

. ! w .. . ... ..

.OEO St = .....

oSfl; VV ]1

, b.

1.0E-01 lv .', ,II -'x'-- I -W.  : \. L r.

1.0E-02 At 1.OE-43 II I.0E-04 1.OE-05 1.OE-06 0 50 100 150 200 25(

Frequency, Hz

-LC_2 AveMSLAUpper -LC_1 AveMSLAUpper Figure 1: Steam Dryer Stress Limit Curve - MSL 'A' Upper MSL A Lower 1.OE+O --

1.OE-01 1.OE-02 -

1.OE44 1.OE-04 A AA t nra^^

0 50 100 150 200 250 Frequency, Hz

-FLCe2 AveMSLtAmLDwer S s -LCt Ave- MSL'AvLower Fiaure 2: Steam Dryer Stress Limit Curve - MSL 'A' Lower

Page 17 of 19 Rev. 1 MSL B Upper 1.0E--j l.OE-02 1.OE-04 1.0E-06 0 50 100 150 200 250 Frequency, Hz

- LC_2 AveMSLBLpper -LC_1 AveMSL,_BUWer Figure 3: Steam Dryer Stress Limit Curve - MSL 'B' Upper MSL B Lower 1.0E+O-, ' _0-0 w0;0-E0i ;00;0:0 1 0E-02 I.OE-03 a 1.OE-04 1 OE-06 1.OE-06 0 50 100 150 200 250 Frequency, Hz

-LC_2 AvewMSLBLower -LC_1 AveMSL_B_Lower Figure 4: Steam Dryer Stress Limit Curve - MSL 'B' Lower

Page 18 of 19 Rev. 1.

MSL C Upper l.E-01 1 E-02 I.E-04 I.E-05 I.E- -.

0 50 100 150 200 250 Frequency, Hz

-LC2 AveMSL_CUpper -LC_1 AveMSL_CUpper Figure 5: Steam Dryer Stress Limit Curve - MSL 'C' UpDer MSL C Lower 1.0E-01 1.OE-02 1.OE-03 I?

t.OE-04 _ _

I.OE-06

=-

0 I ;.-.-I>

50

,,,7*

100

t.

150

:0-200 250 Frequency, Hz

-LC_2 Ave-MSL_C_Lower -LC_1 AveMSLCLower Figure 6: Steam Dryer Stress Limit Curve - MSL 'C' Lower

Page 19 of 19 Rev. 1 MSL D Upper

.OE+*00 - -

I.OE-01 I :q, -f 4w 1.OE-02

'I.OE-03 i 1.OE  :' :0 'ti' ~ ,

~~~~J.'

" ' f 0"-:

-0 - ; 10 .;. 1: 20 250 1.OE-05 1.OE 0 Frequency, Hz

- LC_2 AveMSLDUpper -LC_1 AveMSL.DUpper l Figure 7: Steam Dryer Stress Limit Curve - MSL 'D' Upper MSL D Lower 1.OE+O0 7:7 -7 OE-01 - -. - &

1.OE-02 9

I z'W I.OE-04 1.OE-05 1.OE-06 0 50 100 150 200 250 Frequency, Hz

-LC-2 Ave MSLD -Lower -LCJl AveMS1,_Dower Fgure 8: Steam Dryer Stress Limit Curve MSL ' 'Lower

BVY 06-031 Docket No. 50-271 Attachment 2 Vermont Yankee Nuclear Power Station Steam Dryer Monitoring Plan Basis for Compliance with License Condition 3.M.4 Total number of pages in Attachment 2 (excluding this cover sheet) is 3).

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

Reference:

ERSTI-04-VY1-1409-000, "Power Ascension Test Procedure for Extended Power Conditions 1593 to 1912 MWt (PATP)

Purpose:

This document assesses compliance of changes to the Vermont Yankee steam dryer monitoring models with Vermont Yankee License Condition 3.M.4. In addition, an assessment of the ability of the steam dryer to support operation at the next power plateau is also included herein.

Discussion:

On March 4, 2006 Vermont Yankee Nuclear Power Stations (VYNPS) raised reactor power from 1593 MWt to approximately 1673 MWt, the first power ascension plateau. At that power level the lower set of strain gages on the 'A' main steam line provided an indication at 137 Hz that exceeded the Level 2 Acceptance Criteria of the Steam Dryer Monitoring Plan (SDMP). Entergy Vermont Yankee entered the corrective action program and performed an engineering evaluation which concluded that continuous operation at the first power plateau (1673 MWt) would not challenge steam dryer integrity.

Entergy Vermont Yankee uses an Acoustic Circuit Model (ACM) and an ANSYS Finite Element Model (FEM) to monitor performance of the steam dryer. To address the aforementioned 137 Hz peak, these models have been updated in accordance with requirements established in License Condition 3.M of the Vermont Yankee Extended Power Uprate License Amendment. Details of these changes are discussed later in this document.

The scope of the analyses performed and the results are included in Entergy Vermont Yankee calculation VYC-3001, Revision 1. This calculation includes in part:

• Strain Gage Data from 1593 MWt and 1673 MWt

• Acoustic Circuit Model Benchmark Report

• ACM Uncertainty Evaluation

• Stress Analysis Model Description

• Stress Analysis Results

• Limit Curve Development

• Revised Limit Curves Based on the improvements in the monitoring system and analysis techniques and evaluation of the VYNPS specific signals at 1673 MWt, an engineering evaluation has been completed and has concluded that the strain gage signals are expected to remain below the Level 1 Acceptance Criteria during operation up to and including the next power ascension plateau at 1753 MWt. A summary of the changes to the models and the uncertainty evaluation, along with the new Steam Dryer Strain Gage Limit Curves is contained in the Steam Dryer Monitoring Plan (SDMP) (Attachment 1 of BVY 06-031).

The details of these analyses, including any proprietary documents, have been made available to the NRC Technical Staff for review.

Page 2 of 3 The changes made to the steam dryer models and generation of revised steam dryer limit curves have 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:

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

b. Level 1performance criteria; and

c. The methodology 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."

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, Vermont Yankee concludes that the key attributes have NOT been made less restricted and, therefore, the proposed model and limit curve changes do NOT require NRC approval.

The following changes have been incorporated into the VY approach to steam drye7r monitoring:

1. Incorporation of strain gage accuracy improvements in accordance with License Condition 3.M requirements.

2. Use of an updated CDI Acoustic Circuit Model (ACM) that has been modified to be conservative in the areas of interest and benchmarked against instrumented dryer data from several power levels at Quad Cities. The ACM update to address industry operating experience is required by the License Condition.

3. Revisions to the Finite Element Model (FEM) to incorporate refinement of model in areas of concern related to past failures at Quad Cities and Dresden as required by the License Condition.

4. Generation of a new Uncertainty Calculation based on plant data and the changes above as required by the License Condition.

5. An updated Level 1 Limit Curve representing a conservative reduction of the ASME design limit (13.6 ksi) by the values obtained in the uncertainty assessment.

6. There have been no changes to the Computation Fluid Dynamics (CFD) Model or the role of the CFD analysis to provide additional conservatism for low frequency flow sources.

Page 3 of 3 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 application of model refinements that provide for higher accuracy in determining Vermont Yankee specific dryer stress limits does not constitute a change in methodology. 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.

As required by License Condition 3.M the output of the strain gages is generated as input to the Acoustic Circuit Model (ACM) analysis. The ACM generates pressure loads on the Steam Dryer using the Helmholtz equations. The ANSYS FEM code is used to generate stress loads for affected components of the dryer.

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

==

Conclusion:==

1. Based on the analysis performed using VYNPS Strain Gage data taken at the 1673 MWt plateau and employing the improved models as required by the EPU License Amendment the VYNPS Steam Dryer is not expected to reach Level 1 Acceptance Criteria prior to or at the next power ascension plateau (1753 MWt) and Power Ascension can continue.

2. The SDMP has not been made less restrictive by the changes made to the ACM and FEM and prior NRC approval is not required to implement these changes.

Preparer: Craig Nichols s/. =?,6 64 Name L/ Signature Date Reviewer: James Callaghan 3/e Ir Name C-' Sigrgfre Date Reviewer: James DeVincentis 3 &

Name Signature Date