ML081010451

Technical Specifications (TS) Changes TS-431 and TS-418 Extended Power Uprate (EPU) BFN Steam Monitoring Plan

ML081010451
Person / Time
Site:	Browns Ferry
Issue date:	04/04/2008
From:	Langley D Tennessee Valley Authority
To:	Office of Nuclear Reactor Regulation
References
TAC MD5262, TAC MD5263, TAC MD5264
Download: ML081010451 (10)

Text

ENCLOSURE 5 TENNESSEE VALLEY AUTHORITY BROWNS FERRY NUCLEAR PLANT (BFN)

UNITS 1, 2, AND 3 TECHNICAL SPECIFICATIONS (TS) CHANGES TS-431 AND TS-418 EXTENDED POWER UPRATE (EPU)

BFN STEAM DRYER MONITORING PLAN

STEAM DRYER MONITORING PLAN Introduction and Purpose The Browns Ferry Nuclear Plant (BFN) Steam Dryer Monitoring Plan (SDMP) provides actions for monitoring of Units 1, 2 and 3 for evidence of flow induced vibration that could result in fatigue stress limits being exceeding for the steam dryers. Steam dryer stress analyses have been performed based upon measurements of pressure pulsations in the main steam lines (MSL) at 3458 megawatt thermal (MWt) determined by arrays of eight strain gages mounted in two separate locations on each steam line for a total of eight arrays. These pressure pulsations provide input to an Acoustic Circuit Model (ACM) which predicts cyclic pressure loads on the steam dryers. The cyclic pressure loads provide input to a Finite Element Model (FEM) of the steam dryer which calculates maximum and alternating stresses that can be compared to ASME Code limits.

During power ascension above 3458 MWt, data from the same strain gage arrays are recorded and used to predict changes in steam dryer stress as the steam line signals change with increasing steam flow. This is accomplished by comparing the frequency spectrum and amplitude of the strain gage signals at each of the eight array locations to established limit curves.

Scope The SDMP applies to BFN Units 1, 2 and 3 above 3458 MWt until testing is completed at 3952 MWt and final results are submitted to the NRC. Long term steam dryer inspection is also performed to verify steam dryer performance at extended power uprate (EPU) conditions. These inspections are governed by BWRVIP-139.

Portions of the SDMP are required to comply with license conditions associated with the EPU license amendment. These license conditions are listed in Table 3.

Power Ascension Test Control EPU power ascension above 3458 MWt is performed in small controlled steps in conjunction with the EPU power ascension test plan (PATP).

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HOLD POINTS Hold points above 3458 MWt will be established at increments of approximately 2.5% of 3458 MWt for data collection and evaluation.

TEST PLATEAUS EPU test plateaus will be established at intervals of 5% of 3458 MWt according to the table below. Thermal power will not be increased above the plateau until steam dryer test results are evaluated. Each 5% plateau will be held for a minimum of 96 hours0.00111 days <br />0.0267 hours <br />1.587302e-4 weeks <br />3.6528e-5 months <br /> to allow for NRC review.

EPU Test Plateaus Relative to 100% 105% 110% 115%

3458 MWt Power (MWt) 3458 3631 3804 3952 Two levels of acceptance criteria are used for the SDMP.

LEVEL 1 Level 1 criteria indicate that limits could be exceeded.

If level 1 criteria are exceeded, reactor power is promptly reduced to a previously acceptable power level until an engineering evaluation concludes that further power ascension is justified.

LEVEL 2 Level 2 criteria indicate that limits are being approached.

If level 2 criteria are exceeded, power ascension is promptly suspended until an engineering evaluation concludes that further power ascension is justified.

Monitoring Parameters For the SDMP, the parameters to be monitored are shown in Table 1.

Stress Limit Curves Limit Curves (LC) - Unit specific LCs are developed based on unit specific steam line data, dryer design and analyzed dryer stresses at 3458 MWt. These curves utilize the resolved end to end bias and uncertainty determination developed from the qualification of the MSL strain gage, ACM, and FEM E5-2

methodologies. During power ascension, MSL strain gage signals are filtered and converted to power spectral density (PSD) for comparison to limit curves. Two levels of criteria are established. Table 2 provides the actions to be taken if the LCs are exceeded.

LEVEL 1 The Level 1 criteria curves represent the 3458 MWt acoustic signature for each point in the frequency spectrum scaled by the most limiting alternating stress ratio from the stress analysis. The Level 1 limit curves provide a conservative safeguard against the potential for dryer stresses becoming higher than allowable (13.6 ksi).

LEVEL 2 The Level 2 criteria curves represent 80% of the Level 1 limit curves (10.88 ksi). These curves will be used for evaluation of plant data as collected at each test plateau.

Refer to CDI Technical Note No. 07-30, "Limit Curve Analysis with ACM Rev. 4 for Power Ascension at Browns Ferry Nuclear Unit 1," for a detailed discussion of the LC development.

NRC Notifications At each of the 5% power plateaus above 3458 MWt or if strain gage signals exceed the established Level 1 criteria, an evaluation of steam dryer performance from the SDMP will be provided to the NRC Project Manager via electronic transmission or fax. TVA shall not increase reactor power above the power plateau for a minimum of 96 hours0.00111 days <br />0.0267 hours <br />1.587302e-4 weeks <br />3.6528e-5 months <br /> from the time of the NRC's receipt of this information. This process will be repeated at each of the 5% power plateaus until EPU conditions are reached.

Results of the SDMP will be submitted to the NRC in a report within 60 days from completion of steam dryer power ascension testing.

NRC Approvals NRC approval is required prior to changes that result in the following key attributes being less restrictive:

" During initial power ascension testing above 3458 MWt, each test plateau increment shall be approximately 5 percent of 3458 MWt.

" Level 1 performance criteria; and E5-3

• The methodology for establishing the stress spectra used for the Level 1 and Level 2 performance criteria.

Long Term Actions

" BFN dryers will be inspected at each of the following two refueling outages following completion of the EPU power ascension.

" Inspections to be per General Electric Services Information Letter (SIL) 644, and/or BWRVIP-139, latest approved versions.

" Moisture carryover measurements will continue after power ascension based on SIL 644 recommendations.

• Equipment associated with temporarily installed pressure and vibration monitoring may be removed from service following achievement of one operating cycle.

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Table 1 - Steam Dryer Surveillance Requirements during Reactor Power Operation above a Previously Attained Power Level Parameter Surveillance Frequency Moisture Carryover Every 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> during power ascension (MC) (Notes 1 and 2)

Main Steam Line At least once at every 2.5% above (MSL)Pressure data 3458 MWt from strain gages AND Within one hour after achieving every 2.5% above 3458 MWt(Note 3)

Main Steam Line data At least once at every 2.5% above from accelerometers 3458 MWt AND Within one hour after achieving every 2.5% above 3458 MWt(Note 3)

Reactor pressure, At least once at every 2.5% above water level, 3458 MWt individual steam line flow, and AND feedwater flow Within one hour after achieving every 2.5% above 3458 MWt(Note 3)

Notes:

1. MC to be in accordance with the recommendations of GE SIL 644, Sup 1, Rev. 1. Provided that the performance criteria are not exceeded, when steady state operation at any given power level exceeds 168 consecutive hours, MC monitoring frequency may be reduced to once a week.

2. If MC cannot be determined within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> of achieving a 5% 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 MC was previously determined to be acceptable.

3. MSL pressure data shall be measured hourly when increasing power above a level at which data was previously attained.

Data is required once at each 2.5% power step above 3458 MWt. If the surveillance is met at a given power E5-5

level, additional surveillances do not need to be performed at that power level where data had been previously obtained.

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Table 2 - Steam Dryer Performance Criteria and Required Actions Performance Criteria Required Actions if Performance Criteria Exceeded and Required Completion Level 2: 1. Promptly suspend reactor power

" Moisture ascension until an engineering Carryover evaluation concludes that further (MC)>0.1% power ascension is justified.

OR 2. Before resuming reactor power ascension, the steam dryer performance

" MC > 0.1% and data shall be reviewed as apart of an increases by engineering evaluation to assess

> 50% over the whether further power ascension can be average of the made without exceeding the Level 1 three previous criteria.

measurements taken above 3458 MWt OR

" Pressure data >

Level 2 Spectra (Note 1)

Level 1: 1. Promptly initiate a reactor power

• MC > 0.3% reduction and achieve a previously acceptable power level within two OR hours, unless an engineering

• Pressure data evaluation concludes that continued exceed Level 1 power operation at the current power Spectra level 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 MC and perform an engineering evaluation of steam dryer structural integrity. If the evaluation does 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 evaluation supports continued operation, implement step 3.

3. If the engineering evaluation supports continued operation, reduce further power ascension step increases and plateau levels to nominal increases of 1.25% and 2.5% of 3458 MWt, respectively, for any additional power ascension.

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Notes:

1. The steam dryer limit curve spectra and dryer stress to MSL frequency correlations shall be determined and documented in an engineering calculation or report.

Acceptable Level 2 shall be based on maintaining <10.88 ksi. Acceptable Level 1 Spectra shall be based on maintaining <13.6 ksi. The Level 1 and Level 2 LCs and stress limits shall be adjusted for uncertainty.

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Table 3 - Steam Dryer License Conditions Requirement

<This table will contain the final approved steam dryer license conditions.>

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