ML20197E826

Final Deficiency Rept 86-04 Re 21 Rejectable Weld Indications Identified During Preservice Insp.Initially Reported on 860409.Relief from Repair Requirements Will Be Requested for 12 Unacceptable Indications

ML20197E826
Person / Time
Site:	Byron
Issue date:	05/09/1986
From:	Ainger K COMMONWEALTH EDISON CO.
To:	James Keppler NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
References
1676K, 86-04, 86-4, NUDOCS 8605150324
Download: ML20197E826 (7)

Text

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Commonwealth Edison O

,. .. C ) One First Nitionti Plata, Cluctgo. Ilhnois >

O Addrsss Riply to: Post Office Box 767 ,

Chicago, Illinois 60690 May 9, 1986 a

t 1

Mr. James G. Keppler  ;

Regional Administrator l U.S. Nuclear Regulatory Conunission i Region III

] 799 Roosevelt Road l 1 Glen Ellyn, IL. 60137 i .

4 L i

Subject:

Byron Station Unit 2 .

t 10CFR50.55(e) Report No. 86-04 Rejectable Indications Identified During Preservice Inspection of Steam Generators  ;

f and Pressurizer '

NRC Docket No. 50-455

) Reference (a): October 11, 1985 letter from K.A. Ainger

to H.R. Denton i

l.. '

Dear Mr. Keppler:

On April 9, 1986, the Comunonwealth Edison Company Project Engineering Department notified Mr. R. Lerch of your office of a deficiency reportable pursuant to 10CFR50.55(e) regarding twenty-one (21) rejectable weld indications identified during the Unit 2 Preservice Inspection at Byron  ;

Station. This letter fulfills the thirty (30) day reporting requirement and i is considered a final report. For tracking purpose, this deficiency was  !

j assigned number 86-04.

Description of Deficiency 1

Preliminary preservice inspection examinations, performed prior to i

system hydrostatic testing, identified 45 ultrasonic indications in welds of 4 the Byron Unit 2 steam generators and pressuriser. Eight (8) of these  ;

indications were removed from the welds by grinding. Three (3) indications l were removed by core sampling.

Supplemental non-destructive examinations and metallurgical' analysis of the weld samples were subsequently performed to determine the nature, cause i and actual sizes of the indications. Visual inspections of weld inner J

diameter surfaces identified the source of ten (10) indications as surface l geometry. Analysis of the weld samples verified that the remaining weld ~

indications are small slag inclusions formed during the fabrication process.

8605150324 860509 #

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Mr. J.C. Keppler May 9, 1986 i 4

l l h slag inclusions are located between weld pass interfaces. h analysis

also demonstrated that ultrasonic examination techniques exaggerated the length and through-wall dimensions of the indications by at least a factor of

)

two.

1 Hydrostatic testing and the official preservice Inspection of the Byron Unit 2 steam generators and pressurizer were then completed. N

official inspection was performed to the requirements of ASME Section II 1977 i 4 Edition with addenda through Summer 1978 Addenda. Two additional indications )

i were identified in a steam generator weld during the official inspection. l These indications were characterized as unacceptable to Section II l i requirements. Previously identified indications were re-examined with ultrasonic techniques. h se reexaminations identified ten (10) indications

. as unacceptable.

I I The twelve (12) indications-identified as unacceptable during the j official Preservice Inspection and the nine (9) indications removed from the .

welds were reported to Region III on April 9, 1986. All but one indication l j are located in steam generator welds. The disposition of all 47 indications I are provided in the attached tables.

! Analysis of Safety Implications i 4 Stresses due to system pressure and repeated heat-ups and cooldowns l

! have the potential for causing Code rejectable weld indications to propagate into through-wall cracks. There is a possibility that such propagation might occur before it could be detected by nondestructive testing during the first '

inservice inspection interval.

l j For the indications in the pressurizer, a through-wall crack would

. result in reactor coolant system (RCS) leakage. In such an event, the loss of l

] RCS inventory is expected to be small and would be detected by the various l available reactor coolant inventory monitoring systems.

I l For the indications in the steam generators, a through-wall crack would result in a secondary system steam leak. If such a leak occurred, the j leak would be expected to be small and it would be detected by a change in the

{ containment environmental parameters as well as a change in the containment sump inventory.

l In both cases of weld indication propagation, the resultant leaks are

] expected to be promptly detected in order to prevent any adverse safety

! consequences.

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i l l

2 i.

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l Mr. J.G. Keppler May 9, 1986 4 .

n Corrective Action The twelve (12) unacceptable indications have been characterized as  ;

very small innocuous slag inclusions based on ultrasonic test data, analysis

of weld samples, and information gained during grinding. Since the small slag j inclusions are expected to have little affect on vessel weld integrity,~ the present condition of the components will not reduce the level of plant j safety. The integrity of the vessels can be best preserved by not removing I the indications. Fracture mechanics analyses have been performed which accept the indications in the component welds for the forty (40) year plant life. j l

The preliminary preservice inspection data, details of visual 3 examinations, weld sampling and grinding, and preliminary fracture mechanics i were submitted to NRR in reference (a). . The official inspection results and i final fracture mechanics analyses will be submitted in the near future.

Relief from repair requirements will be requested for the twelve (12) i unacceptable indications.

i Our disposition of the indications has been discussed previously with l NRR. Relief from further repairs is expected after their review of the final fracture mechanics analyses. Since the approval should be given shortly, this j letter is considered a Final Report.

l Please address any questions that you or your staff may have 4

concerning this matter to this office.

4 i

j Very truly yours,

.i i,

l K.sA. Ainger i Nuclear Licensing Administrator

, 1 j Attachments j cc: Byron Resident Inspector

Director of Inspection and Enforcement U.S. Nuclear Regulatory Commission

' Washington, D.C. 20555 1676K i

1 r

i DFFICIAL PRESERVICE INSPECTION (PSI) RESULTS FOR '

THE BYRON UNIT 2 STEAM GENERATORS AND PRESSURIZER SHELL WELD 3 TABLE A-1 SURFACE INDICATIONS EXCEEDING THE REOUIRENENTS OF ASME SECTION XI, TABLE IWB-3511-1 Walt Distance Thru Thickness Length From I.D. Wall Weld Cgegeogy_

, Ng, Cgeoggggg ggee Lgengigo _15:1_ _11:1_ _1s:1_ _1d:1_ _st1_ _stg_

0.01 0.14 0.21 4.7% 60 degree scan showed 2095 SGC-02 224 5/8 CCW 3.2 0.70 1-10 2.8% thru wall.-

(Preliminarily reported as 7.8%)

0.75 0.02 0.43 0.60 11.2% Removed by grinding i 1-2 2095 SGC-06 110 1/2 CW 4.0 8/85 1.0 0.05 0.37 0.42 12.4% Removed by Grinding 1-3 2096 SGC-05 212 3/4 CW 3.4 6/85 0.75 0 0.24 0.32 6.0% Removed by Grinding 1-4 2096 SGC-06 229 CW 4.0 I

8/85 0.88 O O.24 0.27 7.3% Core sample removed 1-5 2097 SGC-02 107 1/4 CW 3.3 6/85

?

3.4 0.75 0 0.36 0.60 10.9% Preliminar11y reported 1-60 2097 SGC-02 219 1/4 CW as 11.2%

i 1.0 0 0.33 0.33 8.3% Removed by Brinding 1-7 2097 SGC-06 42 1/2 CCW 4.0 8/95 3.5 0 0.45 0.13 11.3% Removed by Grinding 1-0 2097 SGC-06 139 1/4 CW 4.0 6/05 0.5 0 0.31 0.61 7.8% Preliminarily reported i 1-93 2097 SON-02 11 1/4 CW 3.2 as 9.7%.

3.25 0 0.51 0.16 12.8% Removed by grinding 1-10 2098 BGC-06 40 5/8 CCW 4.3 6/95 j

O Plotted on flaw handbook charts.

e

DFFICIAL PRESERVICE INSPECTION (PSI) RESULTS FOR .

THE CYRON UNIT 2 STEAM GENERATORS AND PRESSURIZER SHELL WELDS TABLE A-2 SUBSURFACE INDICATIONS EXCEEDING THE REQUIREMENTS OF ASME SECTION XI, TABLE IWD-3511-1 .

Walt Distance Thru Thickness Length From I.D. Wall Weld el%- Ceessots-Lesat190 11"1- J s "l- 19"1- ell- _

Nez Ceme90so% Dste it "1-1.97 0.235 0.16 3.0% Not reported during SGC-02 91 1/2 CW 3.2 0.75 the preliminary -

f2-to 2095 examination.

1.50 0.41 0.34 6.4% Not reported during SGC-02 94 CW 3.'z O.6 the preliminary 2-20 2095 examination.

0.5 1.1 0.31 0.31 4.0% Removed with core 2095 SGC-02 100 1/2 CCW 3.2 sample at 110" CCW

2-3 '

(see next item) 0.16 0.53 0.30 0.3% Core sample removed.

SGC-02 110 CCW 3.2 0.08

2-4 2095 0.80 0.40 0.23 6.5% Preliminarily reported SGC-03 20 5/8 CW 3.1 0.00 as 6.7%

!2-5 e 2096 0.90 0.60 0.34 8.8% Preliminarii;Teported 127 CW 3.4 0.00 i2-64 2096 SCO-05 as 0.4%

0.22 0.15 3.4% Preliminarily reported 82 CW 3.2 0.75 0.11 2-70 2097 SGC-05 as 3.3%

0.26 0.15 4.1% Preliminarily reported 49 3/4 CW 3.2 0.88 0.26

,2-02 2097 SGC-05 as 4.1%

l 0.26 0.19 4.0% Preliminarily reported to 3/4 CCW 3.2 0.70

• O.26 2-93 2090 SGC-02 as 4.1%

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1.94 0.325 0.23 4.0% Marginally exceeds SGC-06 134 3/4 CW 4.0 0.70 acceptance criteria of 2-103 2098 3.9%. (Preliminarily reported as 4.4%).

0.64 0.32 0.0% Preliminar11y 142 CW 4.0 1.00 0.40 2-11e Press PC-04 reported as 8.4%.

1741 o Plotted on flaw handbook charts.

7.

. 0FFICIAL PRESERVICE INSPECTION (PSI) RESULTS FOR .

THE BYRON UNIT 2 STEAN GENERATORS AND PRESSURIZER SHELL WELDS TABLE A-3 INDICATIONS ACCEPTABLE TO THE REQUIREHENTS OF ASNE SECTION XI (PROVIDED FOR INFORMATION ONLY)

Walt Distance Thru Thickness Length From 1.D. Wa!!

Weld _qLt_ Ggementg_____

Segg Locgt(gn _it;L_ _i(1L_ _ig"L_ _id"L_ _qfL_

Ngt gogggngn(

SGC-05 OO CW -- Confirmed as I.D. geometry by visual examination. --

3-1 2095

-- Confirmed as I.D. geometry by visual examination.

3-2 2095 SGC-05 48 CW SGC-02 109 1/4 CCW -- Not reportable. ??'tected < 50 % DAC maximum amplitude) 3-3 2095 2095 SGC-02 131 1/4 CCW -- Spot indication.(Detected as 52 % DAC max. ampI. with 3-4 no measureable depth) --

SGC-03 36 3/4 CW -- Not reportable. (Detected < 50 % DAC maximum amplitude) 3-5 2096 SGC-06 54 7/D CCW -- Confirmed as I.D. geometry by visual examination. --

3-6 2096 SGC-OB 132 1/4 CW -- Not reportable. (Detected < 50 % DAC maximum amplitude) 3-7 2096 '

190 3/4 CW -- Confirmed as I.D. geometry by visual examination. --

3-0 2096 SGC-05 SGC-01 207 3/8 CW -- Confirmed as I.D. geometry by visual examination. --

3-9 2097

-- Repeat of indication at 219 1/4 CW. (See Table A-1) 3-10 2097 SGC-02 217 CW SGC-05 40 1/4 CCW -- Confirmed as I.D. geometry by visual examination. --

3-11 2097 '

7 SGC-05 45 1/2 CCW -- Confirmed as I.D. geometry by visual examination. --

3-12 2097 SGC-06 43 CCW -- Removed by grinding with indication at 42 1/2 CCW. (See Table A-1) 3-13 2097 SGC-06 44 1/2 CCW -- Confirmed as I.D. geometry by visual examination. --

4 3-14 2097 4

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TABLE A-3 (CONTINUED) ---

Walt Distance Thru Thickness Length From I.D. Wall Weld Cggggg%s_

99^2 L95^%A9D 11"E- ll "l- 19"l-jd_"J_ _af]_ _pft_

U91 C9?D9D9Dt 2097 SGC-06 115 7/8 CCW -- Confirmed as I.D. geometry by visual examination. --

3-15 110 1/2 CCW -- Confirmed as I.D. geometry by visual examination.

3-16 2097 SGC-06 3-17 2090 SGC-02 11 1/8 CCW -- Repeat of indication at 10 3/4 CCW. (See Table A-2) --

0.4 0.26 0.20 0.25 3.1% Allowable a/t = 4.1%

3-10 2090 SGC-02 11 7/8 CCW 3.2 3-19 2090 SGC-06 40 CCW -- Removed by grinding with indication at 40 5/8 CCW. (See Table A-1) 3-20 2098 SGC-06 132 1/4 CW -- Not reportable. (Detected < 50 % DAC maximum amplitude) --

4.0 0.5 1.96 0.26 0.26 3.2% Allowable a/t = 4.2%.

3-21 2098 SGC-06 129 CW This data from the

. preliminary exam.

Confirmed as not reportable during official PSI.

0.5 0.27 0.26 0.26 4.1% Allowable a/t = 4.2%.

3-22 2090 SGC-03 39 1/2 CCW 3.2 This data from the preliminary exam.

Confirmed as not reportable during official PSI.

3-23 Press PL-01 7" to 17" -- Not reportable. (Detected < 50 % DAC maximum amplitude) --

1741 belew PC-02 Press PL-02 15 5/B" -- Evaluated as originating from metallurgical structure at the clad / base 3-24 1741 from PC-02 metal interface. Indication as approximately 1 1/2" from weld centerline.--

Press PC-03 75 1/2 CW -- Evaluated as originating from metallurgical structure at the clad / base 3-25 1741 metal interface. Indication is approMimately 1 1/2" from weld centerline.--

Press PC-04 5 1/4 CW -- Evaluated as originating from metallurgical structure at the clad / base 3-26 1741 metal interface. Indication is approximately 3/0" from weld centerline.--

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