M& Dukef drEnergy.

{: ; , - w - i ~ - .. * -, 1: are 41 -/ , 1;_ j^i: ;wI ., ": : ^::s v, :. ~ - :.-" 9 :r -. . ................... w: -_zi Ad :. Ir

Duke Energy - OconeeNIuclear Station SteamGenerator Wear RootCause Update with NRCApril 10, 2006

A11

ENCLOSURE 2

raEnergy.

Topics ofdiscussion* Introductions* Review of Unit I and 2 ROTSG Wear* Preliminary Probable Causes

* Alloy 690 / 410S Tube Support Plate (TSP) material couple and Increased WearCoefficientTube to TSP relative rotation and reduced contact area

* Steam Nozzle Flow Restrictor Acoustic ExcitationLow Frequency Pressure PulseHourglassed Broach Plate Annular Flow Instability

* Preliminary Metallurgical Observations* Plan for Future Activities* Conclusions

2

ONS I Wear Distributions 'a-Dukere' Energy.

ONSI A Tube Support Plate__ __

_____ 2 "3: [4 ]~5` 6 7 '9 10- 1 213"'14~ 15. Total%tw<=5 __ 1 4 231 1 5 2 1 17 6 1 3 1005<'%/tw<=10 4 5 2 946 3181 383 344 228 110 121 1 157610<%tw<=15 1 2 _ 8 89j 157 102 83 49 50 5 5481 5<%twv<=210 13~7T7 31 16 8 14 1 13020<%tw<=25 __ _ _ i 1 9 1 5 3 2 4025<%tw<=30 __ _ - _1 5 31 1930<%tw<=35 __ __ _ _ _8 4 __ 1 235<%tw<=40 2 2 -4

40<%/ltw<=45 ___2 2

50'<%tw<z=55 __J___ 0

55% tw> 60 __ _ _ _- _ _ - _ _0

Total/Suppor 51_ 7 ---ml3 01 9 581 444 648 522 348 173 200 7 2431

ONSI-B ____Tube Support Plate __ __

T1~-2 3 ' 5. )~678~IZ01112,i314i5Total%w=3 2 15 12 191 311 5 1[ 1 107

5<%tw<=I0 1 9 615_-2 1-. -30 34 2.53 _402 174 4 55 174 10 116010<%tw<=15 1 II _ 281 130 80 2 5 68[ 2 32115<%tvv<=20 ______I__- - -71 40 35 17 1 100120<%hv<=25 - 1_ 21 15 11 1 3 __ 33125<"%'tw--=30 ___12 4 1630'<%tw-=35 I5 3 835<%t'dv<=410 __ _ l 1 __ 240'<%tw'v<45 __2

_ 245<%twv<=50 _ __0

50<%'tw<-55 j -__ 0

%tw>60 I~ _ 0aTotal/Support 31 121 91 51 31 1 39 46 3091 6361 3211 81 661 2771 141 17491

4

ONS 1 Wear Distributions P DuketSEnergy.

1 6 0

150

140

130

120

110

100

90 -

80

70 -

60

50 -

40 -

30

20

1 0

n

.. " I w< ga *4 k*(

* at a

Da a j DD

a a a-D

ae a**

at a% a F.S ^D,

, a, a

a, a: 1¢ a

a a* a : 4, p,

1 %% " *a a aO ,

, at a a aj ~ D ,.w g s

' a a '4~t qe > i

Oconee 1-A

TSP (All),X

| 1-5%

D 6-10%

11-15%

16-20%

o 21-25%

* 26-30%

31-35%

36-40%

o 41-45%

. 45

X2

Y 2 Q 1

O 1

O O 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0- 0 M' "I' ` O N CO- 0) 0 - 1 C') V l0 0 N- CO 0) C0 a- 01 ') vN 1) 'ND N" wO

5

ONS 1 Wear Distributions m DukeEEnergy.

Oconee 1-B160

150

140

130

120

110

100 -

90

80 -

70 -

60

50

40 -

30

20

10

0

LV

A -

i�

47 ;IVI , . I I- I.I . , 11

1: -. . . I I .- II

-I

11

-P1

C -

* 0

9��

02 -V 0 0�; -

'�-'�-

TSP (All) I

1-5%

1 6-10%

0 11-15%

i 16-20%

o 21-25%

* 26-30%

31-35%

36-40%

o 41-45%

->45%i~_,

X2

Y 2 Qe;Z YI

X0

OIentat11iono 0 00 a a a: ° 0 0 0 0 0 0 0 0 CD 0 0 0 0 0D 0 0 0 N

(' c ) 'r LO CD N- CD ) 0- - C'4 C) a U) CD N- CD 0) 0 o ~ N ~ m ~ 'q LO (D N- 0

6

m'DukeONS 2 Wear Distributions OEnergy.

ONS2-A11-01-05160

150

140

130

120

110

100

90 -

80 -

70

60

50

40

30

20 -

10 -

0

9Z 9'> . 2 o

* r 2* 5

9* 'T, " to

I o

9 1 * 9 t *

99

9

,:0 "9-0? I

11~ " , @1,

"9C

99¶

* I >t o0

4 ,b * 0

9 99)91 9'v

I* 0 t0

O 9t

9 .. 9,

§~ ..~I99

90

It 9

TSP (All)

-1-5%

- 6-10%

11-15%

- 16-20%

o 21-25%

26-30%

31-35%

36-40%

o 41-45%

. >45%9, 9

99

9 9

9 9

9 9

*99

99 9'K 99 �9:' ;99j9,� ;949�9,

X2

Y2Q YtxOi

Orientation

7D 0 0 0 0 0 0 0 0 0 0 0 0 00 00 0 0 0 0 g ° ° ° ° ° ° 0

- - - - - - N (N N (N N (N (N N (N

ONS 2 Wear Distributions PDukerEEnergy,

160

150

140

130

120

110

100

90

80

70

60

50

40

30

20

10

0

ONS2-B11-04-05

.%*~ ~ 4 .2 4 a4> 4 4 44

* 4 P * s

4 W a a° 4

4<'s A * a

4 *,

5* g -> .

2*'

"4it, 4t

O

4* *

I Ih '

a

O a

44 4'

O o

4 2) .,

4 '

* * f e4 4>) <2< {2

TSP (All)

o 1-5%

' 6-10%

o 11-15%

* 16-20%

o 21-25%

* 26-30%

31-35%

36-40%

o 41-45%

* >45%

I*

.., * + T

XZ2

Orientalio.

z O

O O 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0(Nc Ur) (0 r- U) 0) 0 (N C') ~2 I (0 r- U) 2 ) 0, ('~N m ') LO (0 t- U(N ((N N N (N N (N (N

d

Wear Indications per Steam Generator Duke[Eergye

Original ReplacementOTSG OTSG

SGA 555 1797Oconee UnitlSGB 1232 1450

SGA 428 498Oconee Unit 2 SGB 566 699

SGA 350 Scheduled April/May2006

Oconee Unit 3 Scheduled AprilMSGB 280 Sh l Apr

9

ONS I & 2 TSP Wear Frequency Comparison mb Dukec 'Energy.

CL(1)1--

151.11312 =6".1 :

109 I8-.7

5I p

.. .

Indications per TSPONS2- A

. i . , .. I

i

I .. . .

I 1514131 2I1110

I-7

65432

Indications per TSPONS2-B

! i 'I . ..

a3 -I I " i ;

*a s - ' , i ,

I:z-

o'0 C 0 !C) 0 0 i 0 0 C 0 0IL) 0 UO 0 In) 0 I O U) O U) 0 U) 0 ) O UL C) O L 0

_ ECNlCM MC1C7t t LO)UCO tCO -CO C0) Co

I :.... -- M.- r . .

o C- o o C 0 0 0 0 o 0 0 o CoI) CD ) CD o C) o 0 i ) o ) L o L)- - N C) C'! C') -Tt *r U) ED cD

Frequency

o 0 0 0 0O LO O) LC )r- I- LO) CO LI)

UC) C)CJ) EDC) CD

C

Frequency

1514'1312I110

CL 9a.U) 8I- 7

65432

Indications per TSPONS 1 -A

- :

III

C,0 0 C C)0 0 C) C! ED C) C C) C) ED C C) CD ED 0 C)() 2) E-2 C) LO C) CI) C LO C) U) CD LO C) In C) LO ED LO 0- -C)) CIII.* C' *f* ± ) If) U U3 I- I- a) ET) En M C -I )

Frequency

115

13121 110

CL9c0 8

6J43

1

Indications per TspONSI -3

--- -

C)0C) 0 C) CI C) C.) C) ED CD C 0 a C) C) C1 ED 0 C)Ln o U) o Ln o ) o 1 o U) to Ln o U) Lo U) o UE ) o. s ; J ; ) i 'I i).' 'IJ W l_ I_ U w I.)) U) L

I

Frequency

10

Summary of Review of Eddy Current Data dr9nergy.

..- -... . .. ... ,.....

ONS 1 SummaryONSlA, 2431 indications were found on 1797 tubes

i- ONSI-1B, 1749 indications were found on 1450 tubes* Both ROTSGs 90% of the indications are less than or equal to 15%

of the through wall thicknesst- 50% of the indications are under 10% of the through wall thickness< The vast majority of indications (095%) are present in the

superheated steam region on the 9th tube suppoIt plate and aboveAll indication above the 9th support plate are predominately on theouter region of the bundle.

11

ONS1 Summary (cont'd) fAnergy,

. The highest frequency of indications is at the 1Oth support plate, withthe 1 1tI and 9VI showing the next highest population,

The bleed port is located between the 9111 and IOt' ssupport platethe steam outlet nozzles are located at the elevation of the I itt' supportplate.

Peripheral indications at the 1itO) TSP on both ROTSGs are moretightly distributed and show a tendency to form a "line" orientedrelative to the steam nozzle orientationThere is also a heavy defect concentration directly opposite the steamnozzles on the Y2 axis.

] The 1 5t1 support plate, which is directly below the high cross flowsteam outlet region and has very few indications.For SUppoiA plates 'I0 and above, there are very few indications in theinterior with increasing occurrences towards the periphery

t The peak density of tube wear is typically a fen rows away from theperiphery edgeSupport plate 9 has a significant percentage of indications in theinterior of the bundle. 12

a~lDukeONSI Summary (cont'd) nEnergy,

a- Virtually all indications are tapered wear marks with an anglenominally between 0.3 and 1.2 degrees.Analysis of tube to TSP land clearances indicate no clear relationshipbetween the size of the clearances and incidence of indications.The original OTSGs tube wear is compared against the replacementsin which the distribution of the tube wear in the upper TSPs is similar;although there are more indications for the replacements during thefirst fuel first cycle, than the life span of the original units.

JD The original OTSGs the 9VI and 10til TSP have the most indicationsfollowed by the 8th and the remainder in the upper TSPs.The peak counts occur in the 1 Oth and 1 1itb TSP for the replacementsfollowed by the remainder of the upper TSPs.

2 Only TSPs 7 and 8 differ with significantly more indications in theOTSGs than the ROTSGs.

13

ONS2 Summary All Enu

F,; ONS2-A, 633 indications were found on 498 tubesONS2-B, 903 indications were found on 699 tubes

. Both ROTSGs 90% of the indications are less than or equal to 13% of thethrough wall thickness and 50% of the indications are under 8% of thethrough wall thickness

> lThere are significantly less indications than ONS1 with a less severe weardepth distribution.

'i The highest frequency of indications is at the 1 3t11 support plate for ONS2-Aand the 12th1 support plate for ONS2-B. There is low incidence of indicationson the 9t11, 101t, and 11 support plates when compared with ONS1.Relative to ONSI there are an increased number of indications in the vicinityof the inspection ports in the lower bundle region below the 9th TSP.Based on ECT, wear is predominately single lobe contact similar to ONS1

- Preliminary review of X-Probe data shows no discemnable orientation pattern.

14

Oconee Tube Wear Probable Cause DEnUkegy.

IN To date, no singular technical root cause has been isolated, but fivecontributing causes have been identified by the Root Cause Team(BVVC and Duke Energy)

Probable Technical Causes:

Alloy 690 / 41 OS tube support plate (TSP) material couple andincreased wear coefficientTube to TSP relative rotation and reduced contact areaMain steam nozzle flow restrictor acoustic excitationLow frequency pressure pulseHourgiassed broach plate annular flow instability

15

mge'DukerwEnergy.

Factors Investigated

- ~ ~ -~T,~I::,777,- -- ,17,-- ?' ,' ,. wI ,I I--1 l -I. -~ ~- ,-

16

Factors Investigated M DukePO'Energy.

* Dynamic Pressure Induced Vibration

-Feedwater Spray Nozzle Dynamic Excitation of Lower Shroud;:2Feedwater Spray Nozzle Dynamic Pressure Excitation of Tubes

* Acoustic Induced Vibration

fAxial Acoustic Standing Waves between TSPsF4Acoustic Resonance with Cross Flow Voitex Shedding.-;Steam Nozzle Flow Restrictor Acoustic Excitation of Tubes

FI kIVVC;tLkpI NuJzIe I AJoWJVUOL L..AUILCILII I U1 I UL)ua

17

D ukeFactors Investigated (cont'd) ^ Dnuergy.

Structural Vibration

Steam Nozzle Flow Restrictor Dynamic Excitation of Piping,Shell or ShroudStructural Vibration of Shell due to Mechanical Excitation ofSystem including change in stiffness of ROTSG

. Structural Vibration of Shell due to Ineffective Upper LateralRestraint

Structural Vibration of Shell due to RCP excitation / unbalanceS2 Structural Excitation of Hot Leg (1800 bend) due to RCS flow

perturbations

18

Factors Investigated (cont'd) V nergy.

Flow Induced Vibration

.-fHourglassed Broached Hole Annular Flow InstabilityO.D. Axial Flow Turbulence Induced Excitation

'Axial flow inside tube causing lateral vibration,.Localized cross flow excitation at TSPs within a nominally axial

flow fieldTuHigh Cross Flows and FIV loading in bleed port and steam exit

regionLocalized 'jet pump' effect of feedwater spray nozzles

uExcessive Bleed Flow attributed to steam carryunder in lowerfeedwater downcomerDowncomer flow leakage through lower inspection port sleeves

DFiow Regime instability19

Factors Investigated (cont'd) VDnegy.

Flow Induced Vibration (cont'd)

-Porosity Related Flow Maldistribution at Tube Support Plates

2 Correctness of standard FIV analysis addressing fluid-elasticinstability (FEI), random turbulence (RT) and voitex shedding

L Effects of linear versus non-linear FIV analysis includingclearance limited FEI'Unbalanced feedwater flow through spray nozzles

Z 'U-tube' flow oscillations in lower bundle and downcomer

20

Factors Investigated (cont'd) OFnry

Mechanical I Material Interaction

Effect of broached hole clearancesEffect of tube tension including confir-mation of prestrainEffect of damping in Superheat region

2Relative mechanical interaction between tubes, TSPs, shroud and shell:~Effect of curved versus flat land;~Effect of improved tube I TSP alignment2Material couple wear coefficient

Plant O-perational Thermal Hydraulic Conditions and Geometry21

PhDuke0 Energy.

- I I . I � - .. . � -11 - I - � . � 1. .- - - .. - - - - -- . .- . - --. � . I.. - � I .- ... - -... - -.!- -

Discussion of Probable Causes

22

Alloy 690 1 410S TSP Wear Coefficient Energy.

>I A literature search of wear coefficients was conducted and found awide variation of results for the same materialsComparison of the original material combination to the ROTSGmaterial combination was initiated

E Room temperature sliding tests in a dry environment have providedrepeatable consistent results showing that the wear coefficient forAlloy 690 / 4 1 0S is about an order of magnitude higher than Alloy600/ carbon steel

.< Comparative simultaneous testing in autoclave fretting machines atSuper heated conditions has been initiated to confirm the differencesbetween the original material and ROTSG material combinations

23

Tube to TSP Relative Rotation and Reduced Contact Plkukevnergy.

Volumnetric wear rate is proportional to work rate but throughwall wear rate is related to the contacting surface areaDynam-ic contact between the tube and tube support 'land'should engage the full length of the landRelative angular rotation due to tube dynamic m-otion or rotationof -the TSPs can in crease the wear rate-he Oconee ROTSGs TSPs are vertically positioned by both tie

rod spacers starting from 'the lower tubeshe n b uprblocks around the outer edge of the TSPs which are welded tothe shroud I.D.

24

Tube to TSP Relative Rotation and Reduced Contact cont'd) Lphuke

-2 Relative thermal expansion of the tie rods and the upper andlower shrouds, which are anchored at their bottom ends, causevertical loads at the outer support blocks. These loads result ina dishing of the support plates

k The angular rotation of the support plate edge may bedetrimental to wear due to the possibility of reduced contactareaA relationship between the locations of the tapered wear marksand the angular rotation of the TSPs is still under review

25

Main Steam Nozzle Flow Restrictor Acoustic Excitations Duke

POEnergy.

~~~~~~~~~. - . .I -- -- -- -....................... ^... ...

'! Any sudden shock loss in a steam system is a potential source ofacoustic energy

X An illustration of acoustic energy generation and transmission in apiping system is shown in Figure 10-10 of Blevins (1994)

FB Force on bend

Bend

Area change

Abrupt expansion

Reservoir

Fig. 10-1! A pipe run with an acoustical source at a valve.3

Main Steam Nozzle Flow Restrictor Acoustics cont'd OrEnergy.

Analytical Acoustic Analysis

Determined acoustic energy from steam nozzle flow restrictorpressure drop and velocity using conventional analyticalanalysis

Lin Predicted ROTSG acoustic modesD From acoustic sound pressure levels and mode shapes

determined magnitude and frequency of tube lateral loads- Applied acoustic loading as forced vibration on tubes along with

FIV loads and support contact forces

'Based on analysis, acoustic energy maybe significant,psfpfiaIIy in arpas MAwIa frnm Crmoss fInAXI Fadsk anrI nindr:A!i

covers regions where wear was observed 27

PhDukeMain Steam Nozzle Flow Restrictor Acoustics cont'd OrEnergy.

Search for acoustics

Original and Replacement OTSG Loose Part Monitoring Systemspectral content reviewedSteam line piping (outside of containment) instrumented tomeasure pipe wall accelerations at Units 1, 2 and 3Microphone sound measurements taken around steam line

Direct piessUre transducer measurements taken at ROTSGinspection ports during power escalation following Unit 2 outageMore pressure transducer measurements planned for Unit 3outage as well as containment microphone being installed

28

~PkukeMain Steam Nozzle Flow Restrictor Acoustics cont'd dnergy.

Search for acoustics cont'd

; Unit 2 pressure transducer acoustic frequencies were detectedbut the amplitudes were not as intense as those from predictiveanalysis

> Steam line piping acceleration measurements detected thesame acoustic frequencies as those measured by the ROTSGpressure transducers. Steam line piping accelerations arelargest at Unit 'I followed by Unit 2 followed by Unit 3

29

DfukeMain Steam Nozzle Flow Restrictor Acoustics cont'd VEnergy.

Acoustic analysis conclusions

;< Predictive analysis based on the pressure drop of the steam lineflow restrictor and acoustic modal analysis indicates that theflow restrictor maybe an acoustic source that may explain thewear distribution within the bundleField measurements and analysis of steam line accelerationsindicate a potential that acoustic frequencies exists that mayhave potentially high energy levels

PiPressure transducer measurements at ONS-2 detected acousticfrequencies at intensities less than expected from ONS-Iinvestigations.

30

Low Frequency Pressure Pulse POAueZ.

Unexpected high pressure, low frequency signals wereobserved at the 9th and 1 0th TSP, especially at lower powerduring startup of unit #2 in the fall 2006Signals still being evaluated. There is concern that they maynot represent real pressure

S: Calculations by consultant indicate that energy is sufficient tocause damage if signals are real.Signals at low power may be related to control valve operations.

31

Low Frequency Pressure Pulse PO~nergy.

Low Frequency Pressure Transients during Low Power Operations

N ov 29 1000 hours 18% power G roup 2 T ransducersT S P9

3.

2.

1.

Pressure transientswere Initiated atTSP9 but weredetected also at theother TS Ptra n sd u ce rs. N ote themagnitudes at theotherlocatlons were

.2600 -

.2000 -

.1500 -

.1000 -

35I

J.1 1 iJi 1

.. 2 .4 263 -_ £.

1611.1,1kii AAL,.1 11A..AjLj., "JA -1=0I I "LA- .2000 -4- .2500-

.0000 60.TS P 11

.6000.4000.3000.2000.1000 ,.0000

.2.000 l_.3000

2.4000 .1 .

psi

.3000 4 1

.20004 1 l

-.1000-

_ .3000-

.01000 50

lorgrinsns|linilnr lillli'ilrltilflFlFivllwIIIIT... ~ip¶,I I

I an., V- 111WI-ITHr- II, T111fill 11131f7f -Ipfp�.r. - 111ify I I '1F

boo. 100.00 150.00 200.00 250.00 Sec

113 -*302 ~CM.0I

'I r'boo 0oo.00 1 60.00 200.00 2 '0.00 SeC

1 4 . .70 31s0 .007a

Ai ..,1.,le .,1 ,l, .E ..I . Ai 1. IU 1,1

c TSP 14

i 'ir 32

--------.000 '' 100.00- 1.00 200.00 250.00 XS.c

Low Frequency Pressure Pulse

Low Frequency Pressure Transients during Low Power Operations

P Duker Energye

-AMS Press I-t-W FLONV A (SEL)TWaI Ilowik wbfr ICS FDW DE MAND A [k tb hr]-ICS FDW ERROR A [k Iblhr] --- Rx. PoAer -SO STARTUP LEVEL A(sL)[in].MMNFDWCONTROL VALVE APOSITION[%) -:--ICSMAIN FDW VALVE A [%DMD] -CSSTARTUP FDW VALVEDENIAND A [%]-T D14 . -^ ~iol. ~ T! .vratSa

33

Low Frequency Pressure Pulse hDukerEnergya

Low Frequency Pressure Transients during Low Power Operations

Annular Flow Instability of Hourglassed Broached Hole P'1Euey

Annular flow instability, also known as 'leakage-flow-induced'vibration, typically occurs in cases where a flexible object issituated within an annular flow passage

~ Eiherthe dynamics of the flow field or the varying position ofthe flexible object within the flow passage can cause a variationin the dynamnic pressure around the central objectThe difference in dynamic pressure around the perimeter of thecentral object causes a net lateral pressure force which may bedestabilizing. The motion caused by the lateral force mayincrease the dynamic pressure imbalance and cause furtherlateral motion, hence creating instability.

35

D ukergAnnular Flow Instability of Hourglassed Broached Hole nVergyu

Industry Experience with Annular Flow Instability

Laboratory experiments of divergent nozzle annular flowinstability show that a symmetric annular gap with divergent(expansion) angles of 5 to 150 can cause lateral vibrationIn some cases where the divergent profile had non-symmetricrelief passages, annular flow instability was still observed

* Some research has shown that inlet convergent profiles are astable configurationThe Oconee ROTSG configuration does not match the profile ofa classic unstable profile but has some features that make itsuspect and consequently a test program in air and water flowswas initiated

36

Annular Flow Instability of Hourglassed Broached Hole Duke4MVEnergy.

.--. � .�-...-.� �.

3. Laboir-atory experiments WaterAngle=15°

a) Gormian & al. 1987 (at EdF1in relation with PWR in-core)J

/s

grooves

ISaTong, vibratlions Vibrations No vibratiois

37

Annular Flow Instability of Hourglassed Broached Hole VDukerdvEnergy.

Tube pitch.875'

Original Broached HoleMinimum tubeOutside radius.3125'

MinimumDrill radius.32'

Note: Plate thickness 1.5'

OTSG broached plate tube support

.Original TSP Design

58W Tube Support Plate Design

38

Annular Flow Instability of Hourglassed Broached Hole PVEnuergy.

ROTSG Broached Holed Hole

39

Annular Flow Instability of Hourglassed Broached Hole OvEnkegy,

Results of Analysis and Testing

Air flow tests at hydraulic conditions equivalent to full poweroperation indicate that the hourglassed profile causes increasedtube response relative to the original non-tapered flow passagesThe vibratory motions and frequencies measured do not resultin an exceedingly high work rate at the support interface but aresimilar to those fromn cross flow FIV mechanismsField data does not support annular flow instability as a singularroot cause since axial flow is uniform at all radial positions whilewear predominantly occurs around the periphery

40

ED DukeroEnergy.

Preliminary Metallurgical Studies

41

ONS 2 Tube Pulls FADuke

Two full length tubes were removed from ONS 2 during outage formetallurgical analysis

Westinghouse performing met exam

Macro photography -completeLab ECT - complete

r: SEM/EDX - ill progressLaser profilometry - in pi-ogressMeeting 4/11/05 to discuss results to date and future plansWear tapered consistent with field ECTSliding marks evident on upper bundle defectsPreliminarv observations of wear surface suggest more thanone mode of tube motion likely

42

ONS 2 Tube Pulls ", DukerVEnergy.

1 in

Top

53-114, Pce 32,TSP 14, 1 10 Deg.

: 0 0 t :.0 .. ~, ,0: .:I ' ' I : :-00;...S:::tf 0i:

.: ~ ~~~~ X : i t

43

-

ONS 2 Tube Pulls OEnergy.

1 in

Top

53-114, Pce 28,TSP 12, 120 Deg.

I} 111,11

cC 5aS0:iii S:i;f

44

D hDukeF'OEnergy.

- I I1g 1. If .t - e. - - - - % - ,! . " - re but b e? '! *~ - -,- I; ... z '- - : - ..................... - ::r .

Future direction and conclusions

- .1 -- -..... ..- - -T- .. - - -

45

Status of ONS Steam Generator Root Cause Investigation O Energy,

* Install instrumentation package during spring 06 unit #3 outage,perform analysis of data and compare to unit #2, update root causereport/assumptions

*i Install instrumentation package during fall 06 unit #1 outage,perform analysis of data and compare results of all testing updateroot cause report/assumptions

* Perform 1 00% eddy current inspection of unit #1, establish time rateof wear, validate models and assumptions used in operabilityassessments and evaluations, update root causereport/assumptions

X Transition to corrective actions for probable causes

46

TEST INSPECTION PORT LOCATIONS I DukerE'Energy.

-ACCELEROMETERLOCATIONSEE DETAILVL

l�

I

WI1IIas ItdinWI £0 - ur r.j

| \ TSP 9 Inspection Port(Channel 25- 100 uAlpC)(Channel 26- 100 uA(PC)

47

Concluding Remarks Vfnergy.

* Root cause teams have been meeting on a regular basis and willcontinue through out the summer

• We now kiow more about what is not causing the wear scars andhave 4-5 probable causes

• Testing and data analysis efforts will continue for units #3 this springand unit #1 this fall

X Eddy current results for the fall 2006 outage on unit #1 will give usour first clues as to the time rate of wear and the if new wear scarshave initiated

* Root cause effort should come to some conclusions and beginwinding down by the end of the year unless unexpected results arefound during the unit H1 re-inspection

* ECT will continue on each unit for the foreseeable future48