ML20094K604

Forwards NSD-SGD-1176, Braidwood Unit 1 Interim Plugging Criteria Return to Power Rept & Accounting of Number of SG Tubes Plugged During Fifth Refuel Outage

ML20094K604
Person / Time
Site:	Braidwood
Issue date:	11/13/1995
From:	Tulon T COMMONWEALTH EDISON CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
Shared Package
ML20094K608	List: ML20094K604 ML20094K610
References
BW-95-0109, BW-95-109, NUDOCS 9511170012
Download: ML20094K604 (10)

Text

Y tommonu rah h 1.dison Company llraidw ond Generating Station Rlmtr al, Ika 81 lirard ille,11. (A e(F% I 9

• Tel810:5H2801 November 13,1995 BW/95-0109 U.S. Nuclear Regulatory Commission Document Control Desk Washington, D.C. 20555

Subject:

Comed Braidwood Station Unit 1 Fifth Refuel Outage Steam Generator Inservice Inspection Report Docket No. STN 50-456

References:

(1)

NUREG-1276, Technical Specifications, Braidwood Station, Unit Nos. I and 2 Gentlemen:

Specification 4.4.5.5.a of Reference (1) requires that within 15 days follow'mg the completion of each inservice inspection of steam generator tubes, the number of tubes plugged or repaired in each Steam Generator shall be reported to the Commission in a Special Report pursuant to Specification 6.9.2. A total of 139 tubes were plugged during the Braidwood Unit I fifth refuel outage. Table 1 of Attachment A contains a list of the reasons these tubes were plugged.

Specification 4.4.5.5.d of Reference (1) requires that for the implementation of a voltage based repair criteria for Steam Generator tube suppon plate intersections, the staff should be notified prior to returning the Steam Generators to service should certain conditions arise. None of the conditions of Specification 4.4.5.5.d arose.

Specification 4.4.5.5.e of Reference (1) requires that the results ofinspections of F* tubes be repoded to the Commission prior to the resumption of plant operation. F* was not applied to any Steam Generator tubes during the Braidwood Unit 1 fifth refuel outage. F*

has never been applied to any tubes in the Unit 1 Steam Generators.

Attached is a report on the results from the Braidwood Unit 1 Fiflh Refuel Outage j

(AIR 05) Steam Generator eddy current examination. The examination began on October 7,1995, and was completed on November 13,1995. The examination incorporated the requirements of the 3.0 Volt Interim Plugging Criteria for tube support plate intersections.

A Technical Specification amendment for the 3.0 Volt Interim Plugging Criteria was approved by the NRC on November 9,1995. The attachments summarize the results of this inspection and include a tube plugging history for Braidwood Unit 1.

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[Okt 9511170012 951113 PDR ADOCK 05000456 Q

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November 13,1995.

Page Two t

. Please direct any questions regarding this submittal to Doug Huston, Braidwood Licensing i

Supervisor, (815) 458-2801, extension 2511.

Very truly yours,

/

. Tu on tation Manager Braidwood Nuclear Station TJT/DH/dla bw/95-0109. doc Attachments e

cc:

Senior Resident Inspector - Bmidwood

)

Braidwood Project Manager-NRR Regional Administrator-R111 I

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ATTACHMENT A Summary ofBraidwood Unit 1 Cycle 5.Refuelinn Outane Steam Generator Insocction Results During the Braidwood Unit 1 Cycle 5 Refueling Outage (AIROS), the following Steam Generator (SG) eddy current examinations were performed per Technical Specification (TS) 4.4.5:

100% of the inservice tubes in all SGs were examined full length by a bobbin coil probe.

e Rotating Pancake Coil (RPC) inspection of 100% of the hot-leg Top-of-Tubesheet roll transition regions. Any circumferential cracks found at the Top-of-Tubesheet were funher inspected using the Plus Point probe.

RPC inspections of a minimum of 20% of the Row I and 2 U-Bend sections of the tubes in each SG.

RPC inspection of a minimum of 20% of the tubes expanded at Preheater baffles in the IC SG.

RPC inspection of all hot-leg distorted support indications (DSIs) greater than 3.0 volts, all cold-leg DSIs greater than 1.0 volt, and a minimum of 20% of the hot-leg DSIs between 1.0 volt and 3.0 volts.

Additional RPC inspections to meet the requirements of Generic Letter 95-05, i.e., dents, large mixed residuals, wedge area tubes, etc.

All inspections were performed in accordance with the Braidwood/ Byron eddy current inspection guidelines which include the use of ah alternate probe wear criteria as discussed in Reference 1. A 0.610 inch bobbin coil eddy current probe was used to inspect all SG Tube Support Plate (TSP) intersections where the Interim Plugging Criteria (IPC) was applied. One tube did not pass the 0.610 inch bobbin coil probe. This tube had never allowed a 0.610 inch probe to pass in the past therefore, the obstruction was not caused by a corrosion induced dent. The dented tube was inspected by a RPC probe with no degradation identified. Although no degradation was identified, the station elected to plug this tube.

Table 1 is a summary of the tubes that are plugged in the Unit 1 Steam Generators. During the AIROS outage, a total of 139 tubes were plugged including eighty-6ve tubes due to tube expansion to lock the TSPs. One tube was plugged due to a TSP indication greater than 3.0 volts and fourteen tubes in wedge areas were plugged due to TSP irdications confirmed by RPC. Two tubes were plugged due to Anti-Vibration Bar wear greater than 40% throughwall, and seven tubes were plugged due to miscellaneous reasons. Table 2 contains a tube plugging history for the Braidwood Unit 1 Steam Generators. Table 3 lists the thirty tubes that were plugged due to indications at the top-of-tubesheet roll transition region. F* criteria was not applied to any tubesheet indication (TS 4.4.5.5.e). The data contained in Table 3 has been modified from the field data. Further evaluation of the top-of-tubesheet indications were performed since the 6 eld data had been closed. The field data did not identify any Mixed Mode Indications. Two Mixed Mode Indication are now present. Along with the change to the Mixed Mode Indications, some of the arc lengths have been changed. No missing TSP signals were observed. No circumferential crack-like indications were detected at the TSP intersections (TS 4.4.5.5.d.2). No indications

e

+

were identified that extend beyond the confines of the TSP (TS 4.4.5.5.d.3). No indications were 4

identified at the TSP elevations that are attributable to Primary Water Stress Corrosion Cracking (PWSCC) (TS 4.4.5.5.d.4). No corrosion induced dents were found. There was one cold-leg bobbin coil indication greater than 1.0 volt, but this indication was not confirmed by the RPC probe.

Table 4 is a summary of the IPC data. Table 4 is based on the AIROS Growth Rate Data Base.

This database contains modifications to the voltages assigned to the tube support plate indications, i.e. the maximum voltage indication from the field database is 3.56 volts, while the maximum voltage indication from the growth rate database is 3.17 volts. Minor adjustments to the voltage measurements are typical in IPC inspections. A total of 4136 TSP indications were identified during the AIROS outage. As mentioned above, only one was greater than 3.0 volts.

i 765 indications were between 1.0 and 3.0 volts with 270 (35.3%) inspected by the RPC probe.

J Of the indications that were inspected by the RPC probe to support the requirements of Generic l

Letter 95-05, no degradation was identified by the RPC probe for the tubes with dents or with large mixed residuals. All dents greater than 5 volts (81) were inspected using the RPC probe.

35.4% of the dents between 2.5 and 5.0 volts were also inspected using the RPC probe (RPC inspected 51 of the 144 dents). Since there are no copper components in the Braidwood Unit 1 l

secondary systems, no TSP intersections were found to have interfering signals from copper deposits.

One of the requirements for selecting tubes for expansion to lock the TSP was that the tube shall j

not contain a circumferential crack at the Top-of-Tubesheet Roll Transition. To ensure the absence of circumferential cracks, the RPC data was reviewed by a circumferential crack industry expert. This review is in addition to the Primary and Secondary Analysts review. Once the RPC data confirmed no circumferential crack existed, the tube was examined by the Plus Point probe.

The results from the Plus Point probe examination were reviewed by the same industry expert.

None of the tubes selected for expansion contained a circumferential crack. The requirements for tube expansion were met by expanding twenty-one tubes per SG at a total of seventy-four locations. One expansion at the 8H TSP in the IC SG did not meet the minimum bulge requirement; therefore, a twenty-second tube was selected for expansion at the 8H TSP in this SG. Other expansions in the failed tube met the expansion acceptance criteria, therefore credit was given for these other acceptable expansions. The same selection technique used to select the first twenty-one tubes for expansion was used to select the twenty-second tube in the IC SG.

After the seventy-four expansions were performed, the bulge size was verified to meet the acceptance criteria by bobbin coil profilometry. To examine for axial and circumferential cracking of the parent tube and the expansion sleeve, the expanded area was examined by the Gimble Plus Point probe. The normal Plus Point probe could not be used due to it not being able to expand to reach the maximum diameter of the bulge.

The Probability of Burst (POB) and primary-to-secondary leak rate during a Steam Line Break (SLB) accident were calculated using the actual measured end-of-cycle (EOC) voltage distributions. Since there was a mid-cycle Steam Generator tube inspection in February of 1995, for clarity, the first-half of Cycle 5 is referred to as Cycle SA and the second-half as Cycle SB.

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The calculated conditional EOC-5B POB based on the actual measured EOC voltage distributions i

l and taking credit for the TSPs being locked is less than 4E-6. This POB meets the requirement of being less than IE-2 (TS 4.4.5.5.d.5). The SLB leakage based on the actual measured EOC voltage distribution is 0.07 gallons per minute (gpm). This SLB leakage meets the requirement of being less than 26.8 gpm (TS 4.4.5.5.d.1) when taking credit for the lower reactor coolant Dose Equivalent Iodine-131 limit of 0.35 microCuries per gram Since the POB and SLB lak rate was determined using the actual measured EOC voltage distribution, the estimated SLB leak rate and POB based on projected EOC-6 voltage distribution will be reported to the staff within 90 days of Mode 2 as required by Generic Letter 95-05.

The POB and SLB leak rate was also calculated based on the TSPs not being locked, i.e. freespan leak and burst. These calculations were performed to compare to the EOC-5B projected POB and SLB leak rate. The EOC-5B projected POB and SLB leak rate were calculated using the EOC-5A voltage distribution and projecting this voltage distribution using a probability of detection of 0.6 and Monte Carlo. The actual EOC-5B POB was 6.49E-04 as compared to the projected EOC-5B POB of 4.49E-03. The actual EOC-5B SLB leak rate was 0.07 gpm as compared to the projected EOC-5B SLB leak rate of 0.48 gpm. This shows that the actual measured POB and SLB leak rate are conservative relateve.to the projected POB and SLB leak rate.

References

1. Letter to Office of Nuclear Reactor Regulation from Harold D. Pontious, Jr., " Additional Information regarding Commonwealth Edison Company's Supplement to Technical Specification Amendment for 3 Volt Interim Plugging Criteria for Byron Unit I and Braidwood Unit 1," dated September 15,1995.

l l

Table 1 Braidwood Unit 1 Fifth Refuel Outage (A1R05) SG Tube Plugging Results 1 A SG 1BSG 1C SG 1D SG TOTALS Total Tubes 4578 4578 4578 4578 18312 Previously Plugged Tubes 505 102 706 365 1678 Total Tubes inspected This Outage 4073 4476 3872 4213 16634 A1R05 Tube Support Plate Pluggable 1

0 0

0 1

Anti-Vibration Bar Wear Pluggable 0

1 1

0 2

Confirmed Wedge Location Pluggable Indications 10 0

1 3

14 Top-of-Tubesheet Pluggable Indications (Circ / Axial / Mixed Mode) 8/1/0 2/0/1 8/1/1 5/3/0 23/5/2 Tubes Plugged due to 1 AVB 1 TSP VOL Administrative Reasons 2 Loose Parts 1 AVB 2 Dents 0

7 Tubes Plugged due to TSP Locking to Support the 3.0 Volt IPC 21 21 22 21 85 A1R05 Total Tubes Plugged 44 26 37 32 139 Restart Total Tubes Available 4029 4450 3835 4181 16495 Total Tubes Plugged 549 128 743 397 1817 Percentage of Tubes Plugged 12.0 2.8 16.2 8.7 9.9 SG Tube Plugging Limits are a maximum of 30% in any one SG with a maximum of 24% total.

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j Table 2 Braidwood Unit 1 SG Tube Plugging History Tot al

% Plugged PWSCC AVB WE AR F RE E SPAN ODSCC WEDGE TTS CIRC OTHER (PS4 SG-A 4

0 09 1-Factory, 3-Beeshne l

(PSQ SG-8 1

O O2 1-Factory

[

(PSQ SG-C 6

0.17 8-Beeeline t

(PSg 5G-0 1

O O2 1-Seseline (A1RO1) SG-A 5

0 20 2

3-Fortegn Otnoct

AIRO1) SG-8 1

O 04 1

( AIRO1) SG-C O

O.17 f

(AIRO1) SG-D 0

0.02 i

e 1.162 EFPY F

(A1RO2) SG A 11 0.44 2

8 1-Fortegn Otnoct l

f (A1RO2) SG-8 2

0.09 1

1-NRC BuRatin 88-02

( A1RO2) SG-C 19 0.59 1

18 l

(AIRO2) SG-O 4

0.11 4

0.861 EFPY (AIRO3) SG-A 37 1.25 4

33

( AI RO3) SG-8 11 0.33 11

( A1RO3) SG-C 82 2.38 2

80 L

f

( AI RO3) SG-O 44 1.07 44 1.132 EFPY k

Oct '94 SG-C l

117 l

4.94 l

l l

1 l

116 l l

l 0.852 EFPY (A1RO4) SG-A 186 5.31 1

2 170 13 (A1RO4) SG-8 43 1.27 4

19 0

- 20 TSP Expension Prope I

(AIRO4) SG-C 140 7.99 5

127 8

(A1RO4) 80-0 122 3.74 1

110 11

}

1.1468 EFPY NOTE: ks RO4, a 1.0 Volt IPC was approved for OOSCC.

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(AI MOS) SG-A 262 11.03 2

235 17 4

1-MMI et TTS, 2-VOL et TTS,1-SAI (00) et TTS (AIMOS) SG-8 44 2.23 41 2

1-VOL st TTS (A1 MOS) SG-C 340 15.42 1

315 12 11 1-VOL st TTS i

(A1 MOSI SG-D 194 7.97 180 13 1-SAI(OD) et TTS O71A2 EFPY NOTE: The 15 Circumferene'el Creeks + the 1 MMI were "statWitrod" witts e stoevo.

l

( A1RO5) SG-A 44 11.99 1

to 8

1-SAI(OD) et TTS,1 Adniin AVB, 2 Loose Porte, 21 Expanded Tubes I

(A1RO5) SG-8 26 2.80 1

2 1-MMI et TIS,1 Adenin AVB, 21 Expanded Tubes

{

f 1-sat (OD) et TTS,1-MMI et TTS,1-TSP VOL,2 DNTs. 22 Expanded i

(A1R06) SG-C 37 16.23 1

1 8

Tubes (AIROS) SG-D 32 8 67 3

5 3-SAB (00) et TTS, 21 Expanded Tubeo l

0.506 EF PY NOTE: 3 0 Voet IPC appenved for AIROS outage r

Total P1ue9ed 1817

% Plug 9ed 9.92 Total EFPf 5.522 I

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_ -. _. - _ = - _ - _ - _ _ _ _ _. _ _.. - - - _ _ - -.. -. - - _ _ _. _ _ - _ _ _ _ - - - _ - _ _ - - _ _ - _ _ - -.. _ _ _ - - _. _ _ _.. -, - _.. _ _. _ _ _ - - _ - _ _. _ - _. - - _. _ _ _ - _ _ _ _ _ _ - _ -. - - - _ - _ - - - -

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-m Table 3 A1R05 SG Hot-Leg Top-of-Tubesheet Roll Transition Indications

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Circumferential Cracks A1M05 A1R05 +

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Reenelysis Arc M A1R05 RPC PointArc DetteRPC i

Steam Length Arc Length Length y Arc Lanoth Generator Row Col (degrees)

(degrees)

(degrees)

(degrees)

Comments 104 129 50 1A 20 38 54 27 38 227 312 159 85 21 41 176 162 230 6

y 4

22 41 232 227 259 20 42

)

152 188 213 34 46 45 323 337 338 14 257 258 242 1

25 49 29 61 164 162 127

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, ;zsceimssc > asomv;n m 52e:mmeseassasssuaswswisusemamassassesure -asses:, -fas 1B 23 70 83 159 76 76 25 70 109 203 175 34 4.sssw&

o, sw:-

r

.:sse x

, s.e mii; mm az;<i.: swas

,,-4

, esa ;s<s:

~

10 9

68 182 g

187 69 5

15 99 165 238 242 73 13 102 163 190 326 e

27 2

109 280 357 274 3

77 4

100 284 306 290 9

24 9

110 319 329 344 10 3

111 232 250 314

~

18 4

111 316 354 100 38 m+sent waw

~ hwutunuagu - wexams a msunut m en w s sms u n unw<se c ya ~

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, nxt, 10 11 49 139 146 197 7

24 53 72 107 63 36 352 356 300 4

30 53 ~

• 15 8

66 321 336 323 16 69 154 180 295 26 Axial Cracks

~

A1M05 i

^

DelteRPC Steem Roanalyes A1R05 RPC Analysm Analyses Generator Row Col (volts / degrees)

(volts / degrees)

(volte/deg)

Comments 1A 37 99 0.62 54 s

0.9 52 1C 20 47 0.73 42 1D 10 68 1D 20 69 0.86 58

' ~'

0.68 74 1D 20 71 Mixed Mode Cracks A1M05 A1R05 +

Reenelyes Arc i A1R05 RPC Powit Arc DetteRPC Steam Length Analysas Length Arc Length (longth/deg)

Comments Generator Row Col (length /deg)

(length /deg)

(degrees) 0.35 0.38 0.03 Aionilength in inches 1B 21 72 238 305 353 67 Circur-fsrential degrees 02 0.17

-0.03 Aiaal Lwigm in inches y

1C 21 54 263 304 286 41 Circumforarmel degrees

• Need to size crack i- -

Table 4 Summary of A1R05 Steam Generator Eddy Current IPC Data 1ASG 18SG 1C SG 1D SG TOTAL C..

e.

TSP Indeshons 1031__..

556 1480 106R 4136 TSP irweranone RPC'd 66 90 105 6t,,

327 TSP Inrhr*=hons Confirmed by RPC 45 50 52 5',

200 seese

swg

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cyg as:g.y; w:.e.s3:gw.m ei4 s

ww x

.;csw4 m :o; a.w.is.

TSP Indeshons >1.00 Vous 188 88 301 189 766 TSP Inrte=hnns >1.00 vons RPC'd 49 84 83 56 271 35.3% RPC'd belwoon 1 and 3 volts TSP Irweenhans >1.00 Vots Contwmed by RPC 35 47 46 50 178 w w m3: ges

. sgrss g%sy (;g rpece gg

-gt::;wgcjwwcs.g: Miniggp es:p.,-

wsces:an s:4s:

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TSP Indeshons >3.00 Vots 1

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lvgsassg use sx;pz e rsm$gg. g:ssnp +igisiw sgaygsg.g;ags: 9:4 s:ssq g. uns4.iwe peusen 3:w, y

swiv:-

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-a.p.sp x 4

TSP Indeshons C. 00 Vots 843 468 1179 880 3370 TSP Indestions <100 Vots RPC'd 17 6

22 11 56 TSP Indeshons <1.00 Vots Confumed by RPC 10 3

6 3

22 assa <

a 4>

+& qv<

g# Swniie->.-

.sgs@ gs;>ggsW eb e d e s:g ; s y suss

~ tuw:ws esp 4 +ess-sm y:e v:w.m RPC Confirmed TSP Indeshons in Wedge Area 10 0

1 3

14 es.64pyg sitss:igggaggwsmg;gnem as:t@rj x

x qw:e*

o 9ssse w

s s -a+

t s<we sse,

4 TSP Indeshons Repowed 21 2

19 11 53 TSP trwer=hans Repowed >1.00 VoRs 4

1 3

2 10 x.

v z:e ses 4 app s>*

ps sms we~, #ssupe:-efss?

• JWiMissnWgriteds ~,,sig@N

+

Meamum TSP truer =hnn (VoRs) 3.17 2.03 2.94 2.64 3.17 4

uim 1-emn q!M @tWie:i h - nw augage Mrsepdad-vyssm

-x - swee:vem xsa 4asseer w eem

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t Total TSP Dents 80 42 63 45' 230 TSP Dents >5.00 volts 30 6

39 6

81 AB RPC'd, su NDD TSP Dents 2.50 - 5.00 VoRs 49 33 24 38 144 TSP Denis 2.50 - 5.00 VoRs RPC*d 18 11 14 8

51 35.4% RPC'd, og NDD TSP Dents <2.50 vots 1

3 0

1 5

mssa messwpp

-m - y:que mas;.;qige meer pspse aisne.g ggsgg3 wus ysyys;g:jiigggyigsggg;gia gas.>uespig;3 pep;u-Mered R== k=t Indicehons 3

14 1

7 25 AB RPC'd, as NDD q:g

_eigigii;f gqwg:gjgigeip%mg &nsq;sy

~

$?vi gM;sy +#

5 u

m:a is>p;swa u:sg: + 3g.o 2 sus we.SS gym 1D 50. Dort >5V W GL IG e.

NDO by RPC.

Topef-Tubesheet Circumferenhal Crocks / Axial 1C SG. Dent >5V et HLTubenhest.

l' Crocia14ined Mode Crocks 8/10 20f1 8/1/1 SGO 23/5/2 NDD by RPC.

- - a::$a qww + -

gg ~

ss# ::mppp.... nagggs:33. ilgst. jwgsg:sn ess$l 4 qqwysg

>+newge,, #

aguaker se epve.swq 1 exponeson in 1C SG st 5H Ist"i=M rrunsmumbulgetimmater Expanded Tubes Fvp=nded for 3 Volt IPC 21 21 22 21 85 enaher tube et the 8H TSP.

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Attachment B Westinghouse Report Interim Plugging Criteria Return to Power Report November 19h5 1