ML082890206

TVA Slides - EPU - Summary of October 14, 2008, Meeting with Tennessee Valley Authority Regarding Steam Dryer Portion of the Extended Power Uprate Review (TAC Nos. MD5262 and MD5263)

ML082890206
Person / Time
Site:	Browns Ferry
Issue date:	10/14/2008
From:	Tennessee Valley Authority
To:	Division of Operating Reactor Licensing
Brown, E, NRR/DORL, 415-2315
Shared Package
ML083030525	List: ML082890206 ML083030220
References
TAC MD5262, TAC MD5263
Download: ML082890206 (25)

Text

IH AI TENNESSEE VALLEY AUTHORITY BROWNS FERRY NUCLEAR PLANT ExtendedPowe rate -7j]..

-steam Dryers--

October 14, 2008

Agenda

• Status of Unit 1 and 2 Dryer Analyses

" Decision on Acoustic Side Branches

" Plan to Address SRV Resonance

• Changes in EIC Removal Method

• Unit 2 Noise Removal

" Submodeling Questions

• Review of RAI 19, 20 and 21 Responses

• Schedule 2

Status of Unit 1 and 2 Dryer Analyses *

" TVA Decided not to Install Acoustic Side Branches (ASB)

- No clear advantage

" Unit 1 and 2 Stress Reports (June 2008) Need to be Revised

- SR-a > 2.7 at CLTP

- Evaluates CLTP only

- Unit 2 anomalous low flow (LF) signal (19% power)

- Newer strain gage data now available

" Additional Strain Gage Data

- Unit 1 startup August 2008

- Unit 2 startup September 2008

• Unit 1 Stress Report Being Finalized

" Unit 2 Stress Report in Progress 3

Decision on Acoustic Side Branches

• 24-inch Quad Cities Design Chosen

- Governed by clearance limitations

• Acoustic Design Relied on Damping Effect

- Assumed to eliminate Safety Relief Valve (SRV) resonance

• Confirmation of ASB design by 1/8 Scale Model Test (SMT)

- Damping effect less than expected

- SRV resonance still present

• TVA Decided to Cancel ASB Modification

- No clear advantage to Flow Induced Vibration (FIV)

• Requires Stress Analysis to Address EPU

- Bump-up factor 4

Decision on Acoustic Side Branches [

BFNI With ASBs 25 . . . . . . ...

20 ".....MSL S A Upper 20 ------------------------------------ _ M SL A Low er

_MSL B Upper

__ MSL B Lower 15----------

____ MSL C Upper MSIS (1 Lower

' 10

-- - - - - - - - - - - - - - - - - - - - - - - - - - - ------ a - -- -- - ---- -

0 50 100 150 200 250 Frequency (Hz)

BFN2 With ASBs - MSL A Upper 7 .... .... .... , ,r- - MSL A Lower

_-- MSL B Upper 6 _ i ------- MSL B Lower 0 -- MSL C Upper

-NISL C Lower 4 ----------I-- ----,-- -------e 0

0 50 100 150 200 250 Frequency (Hz) 5

Plan to Address SRV Resonance IRA

• 1/8 SMT Performed for each Unit's Configuration

,- Data at each strain gage location

- Data at CLTP and EPU Mach numbers

• Bump-up Factors Calculated as a Function of Frequency by Equation:

BF = PSDEPu At each frequency PSDCLTP Applied to Plant CLTP Strain Gage Data to Predict EPU Load PCLTP = CCLTP(CLTP - EICcLTP) - CLF(LF - EICLF)

PEPU = BF[CCLTP(CLTP- EICCLTP) - CF(LF- EICLF)]

P = Steam line unsteadypressure C = Coherencefactor between upper and lower locations BF = Bump- up factor for SG location EIC = Signal taken wilh zero excitation voltage LF = Low flow signal 6

Changes in EIC Removal Method SEIC Signal Taken by Removing Strain Gage Excitation Voltage

• Electrical Noise is Removed by Using EIC signal Mechanical Component = SG Signal - EIC

• Additional EIC Signals on Units 1 & 2 EIC now Matched with Companion CLTP and LF Signals PCLTP = CCLTP(CLTP - EICcLTP) - CL,(LF - EICLF)

P = Steam line unsteady pressure C = Coherence factor between upper and lower locations EIC = Signal taken with zero excitation voltage LF = Low flow signal 7

Changes in EIC Removal Method JiV EIC Signals BFNI A Upper EIC BFNI B Upper EIC

-- *C @lD%,Pm.d FO(2M)AU 0.01 0.0001 Ia 0 50 100 150 200 250 0 50 100 100 200 250 Frqpency (Hz) Fmqumney (Hr)

BFNI A Lower EIC BFNI B Lower EIC 0.1

-- FHzWO0W(1Bt tfEZ:QeflflPov.m*

0.1I - - U*E. N%Po-4UdZW.D(5M)8L

--UtE @86%Povmrl4*zWIOrO)AL

-- UECO WIk*Oa01*Hz1W0{

2U)BL 0.01 0.01 I 0001I 0.001 01 a 00001 . .0001 wV-.

000001I 0000001I 0

ffi2_LL 50 100 Frmoncy (Hz) 150 200 250 0 50 100 F.qmency (Hz) 150 200 250 8

Changes in EIC Removal Method iRA EIC Signals BFNI C Upper EIC BFNI D Upper EIC 0-1 0.1

-- -WQet~floVSJUFiZ*WD (TW)OU --U~lECg ewlSS t4HPz WO(736)DU

-- U1E8@o0Po¶.wtvo (2l8,cu 0.01 0.01 0001 0.001 0 0.0001 _ e 0.0001 0.00000_ ....

00l0001 . ..

0 00 100 150 200 250 0 50 100 150 200 250 F-q-n..y (H.)

BFNI C Lower EIC BFN1 D Lower EIC

-- UIEIC@6%P01a11t'4H4 2W0 (1161 C

0.001 0.501 [

I a 0001 Ia 0, 0001 _______ _ _ _ i _ i ____i i 0 s0 100 150 200 250 50 100 150 200 250 Fmquene (Hz) 9

Changes in EIC Removal Method IM EIC Signals BFN2 A Upper EIC BFN2 B Upper EIC 0.1 0.1

-WEC@5%P ýw/HzW(4018U

-WECG$3%POýnHZWO( 2)aU

-WEC@WPOd4HZW(49)BU 0.01 0.001-0.001 S 0.00001 0.00001 0.~0l00 00.001 0 so 100 ISO 200 250 FBAquency (H.) Fmq-.ney (Hz)

BFN2 A Lower EIC BFN2 B Lower EIC 0.t 0.1 001

_ -- EEG

• (228q

%Poý4536Hz'VFO TO 0.01 0.001 1 0.001 ul 0.0001  :  ::

0000 0*00001-0.000001 * - * - . ---

0,000001 '

0 50 100 10S 200 250 0 00 100 150 200 250 Frequency (Hz) Frequency (H1) 10

Changes in EIC Removal Method EIC Signals BFN2 C Upper EIC BFN2 D Upper EIC 0.1-0.01 -- ____ _ 0.01 001 0.00001 0 0 1.0 1.020 210 100 150 200 250 Freqency (Hr)

BFN2 C Lower EIC 01

--L EC (ie)c

@81%,Pov,fOe'6$HzWD

-WEI@1,po.4S ztFD(4)O.

0.01 0.0001 0.00001 _______

0 so 100 150 200 250 Fmq.mnmy (Hz) 11

Unit 2 Noise Removal

• Additional Data Taken on Unit 2 to Confirm Signal Behavior

- Electrical noise on Unit 2 varies with recirculation pump speed (VFD frequency)

- Relationship is not well understood

- 19% power signal originally used for noise removal was atypical

- Composite 19% & 30% power signals replaced

• New LF signal at 5% Power and Companion 5% EIC Signal

- All strain gages -on MSL D lower damaged

- Substituting MSL A for MSL D due to strain gage failures

- CLTP signal and companion EIC signal unchanged 12

Unit 2 Noise Removal PSD Signals BFN2 A UPoer BFN2 B Uppe 1.0E-01 1.0E-01 14 0

50 100 150 200 250 50 150 200 250 100 Fq y(z Fre.n1y (.z)

BFN2 A Lo BFN2 B Lower 1.0E-01 1.0E-02 F1.00E-03 1.0E-03 1*-

1 0-04 I. 01 .00-04 I.0E-05 1.00-00 1.00-06 50 100 150 200 250 Freqency (Hz) Froequcy (Hz) 13

Unit 2 Noise Removal PSD Signals BFN2 C LpW BFN2 D Upep 1.00E01 10E-02 1.00-03 0

(0 .00-04 1.00-06 50 100 150 200 250 Freq-y (Hz)

BFN2 C Loý BFN2 D tow 1.0E-01 1.0E-02 1.0E-03 0

l.E-05 I .00-00 250 so 100 150 200 250 FM.weoy (Ftz) Frequey (Hz) 14

Submodeling Questions Is the Stress Reduction Factor (SRF) accurate and unique?

Would a different analyst get the same solution?

- Limited, Specific Purpose o Avoid excess conservatism of shell model o Based on mechanistic behavior along weld line

- CDI Shell Model => SIA Shell Submodel o Characteristic load matches CDI stress along the weld line Drain Channel-to-skirt: Bending thru the joint - See Figure 1 Hood Stiffener-to-Hood: Membrane in stiffener - See Figure 2

- SIA Shell Submodel => SIA Solid Submodel o Incorporates weld geometry o Applies characteristic loads o Accurately captures load transfer mechanism and stress distribution through weld

- Submodel attributes (loads & boundary conditions) are not unique, but SRF is unique & accurate. So a different analyst would get the same result.

15

S ubmodeling Questions IRAI Submerged Skirt - Figure 1 Node 98156, Skirt 1000 800 CL 600 C

U) 4-400 200 0

50 50.1 50.2 50.3 50.4 50.5 Time [ s ]

16

Submodeling Questions Inner Hood Stiffener - Figure 2 Node 104843, Hood Support 5000 [

4 0 00 .... ... .............. - - -

3000-- --

CD

.-U) 2000oo ..... Ci

-.-Surface  :

0)0 10 0 0 -m id dle .. . . . . . .--

bottom 50 50.1 50.2 50.3 50.4 50.5 Time [s ]

17

Submodeling Questions I--

ft-A-1

• Are the submodel loads statically equivalent to the CDI model?

- No - not statically equivalent, nor required

- Limited objective is to capture stress along weld line

- Simple Example:

REAL BEAM EQUIVALENT BEAM Objective: Design Connecting Weld (For FEA Model)

For Real Beam Using FEA

,=-- M=

M k-ft I k , ,M 10k-ft 10k+

~ILZ Z 0M = 10 k-ft

-21 18

Submodeling Questions Are the times used the ones which yield the largest stress intensity after application of the SRF?

Refer again to Figures 1 & 2

- Alternating stress defined by either membrane or bending extrema

- Extrema states produce maximum strain (i.e., fatigue usage)

- SRF should be based on the extrema stress state

- At other points in time, the product of stress intensity and SRF would have a lower value; i.e., be less conservative 19

Submodeling Questions Demonstrate that the uncertainty in calculating the SRF is small

- Approach produces high certainty that bounding stress of weld line is captured

- Solid submodel mesh sensitivity study demonstrated convergence

- Weld factor of 1.8 retained

- Low level of uncertainty subsumed by bias and uncertainty applied to overall process

- 20

Review of RAI 19, 20 and 21 Responses I-RA-1

• RAI 19

- EMCB.147 (Unit 2 only) o New Unit 2 stress analysis o Revised response based on revised analysis

- EMCB.192/150 o SRV Resonance EMCB.181 Follow-up (Unit 1 only) o 0- 2 Hz mean filter EMCB.182 Follow-up (Unit 1 only) 0 EIC removal

- EMCB.183 Follow-up (Unit 1 only) 0 SR-P values in table 21

Review of RAI 19, 20 and 21 Responses ITVA_

" RAI 19 (continued)

- EMCB.181 (Unit 1) & EMCB.147 (Unit 2) Follow-up 0 PSD plot filtering

- EMCB.186 & EMCB.187 Follow-up (Unit 1 only) o Sub Modeling

• RAI 20

- EMCB. 194 (Unit 1 only) o 9% signal coherence

- EMCB.195 (Unit 1 only) 0 Fan noise 22

Review of RAI 19Y20 and 21 Responses I-R-A-1 RAI 20 (continued)

- EMCB. 196 (Unit 1 only) o EIC plots

- EMCB.197/153 o Strain gage penetration location

- EMCB.154 (Unit 2 only) o 9% signal coherence

- EMCB.195 0 Extended frequency plots - VFD 23

Review of RAI 19 20 and 21 Responses

• RAI 21

- EMCB.198 (Unit 1 only) o EIC removal

- EMCB.155 (Unit 2 only) 0 EIC removal 24

Schedule I Item Date TVA response to RAI 21 on Channel Bow 10/17/08 TVA submit Unit 1 stress analysis & Unit 2 status 10/31/08 TVA submit Unit 2 stress analysis 11/14/08 Tentative ACRS meetings 2/09-3/09 Unit 2 outage begins 4/09 NRC issue EPU Amendment for Units 1, 2, and 3 4/09 Unit 2 startup at EPU 5/09 Unit 1 implement EPU 6/09 Unit 3 implement EPU Spring 2010 25