ML20205T348
| ML20205T348 | |
| Person / Time | |
|---|---|
| Site: | Davis Besse  |
| Issue date: | 09/24/1986 |
| From: | Galligher M TOLEDO EDISON CO. |
| To: | |
| Shared Package | |
| ML20205T294 | List: |
| References | |
| 1166319, TAC-66736, NUDOCS 8704070270 | |
| Download: ML20205T348 (10) | |
Text
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DocN t No. 50-346 License No. NPF-3 THE BABCOCK & WILCOX COMPANY l Serial No. 1-715 POWER GENERATION GROUP l At t achinent l;
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- A4098 Page 1 SA,WA e,th, EDDY CURRENT REPORT FOR seau o ru 09/24/86
,,,,,,,,- e,g g y DAVIS BESSE, UNIT 1 - AUGUST 1986 a?* 1166319 4 O
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Docliet No.30-346 License No. NPF-3 THE BABCOCK & WILCOX COMPANY POWER GENERATION GROUP
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1.0 INTRODUCTION
A total of 2794 tubes were examined in the "A" generator and 2536 tubes
?I were examined in the "B" generator. The inspections were conducted from
$5 the inlet side of each generator. All tubes were examined full-length, 30j with the exception of the 8x1 inspections which were run to the 13th yj tube support plate. All reportable and rejectable indications were rerun g,s for confimation with the bobbin coil and the 8x1 probe. A saturation UEi probe was also used in some of the tubes for indication clarification and
- 3$ confi rmations.
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SUMMARY
iE e! Of the 2794 tubes examined in the "A" steam generator, eighteen tubes le contained indications of approximately 40% TW or greater, or contained ja multiple reportable indications and were plugged. One additional tube gE was rep'ugged because it had developed a leak (this was a welded plug).
gj There were twenty-one tubes with one or more indications of 20% to 39%
!" TW, inclusive, and thirty-nine tubes with one or more indications less gg than 20% TW. 148 tubes contained low signal-to-noise ratio indications.
BI In the "B" steam generator, 2536 tubes were examined. One indication of greater than 40% TW was found and plugged. No other reportable indications were found. There were nineteen indications of less than 20%
TW and sixteen low signal-to-noise ratio indications identified.
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s; All periphery tubes in both generators had a gap of at least .250 inches f* between the auxillary feedwater header and the tube outer wall based on yj the periphery tube examination.
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A post-outage debris analysis of tubes within the "A" generator which had reportable defects was conducted to determine if there was a correlation i between debris and the reportable indications; no unusual debris amounts
[IE were detected.
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Od 3.0 EXAMINATION Ei?
Es The examination, equipment, and personnel were in compliance with the E[3 requirments of the Babcock & Wilcox SPIS QA Manual for Inservice 3 Inspection, the applicable customer technical specifications, the ASME E;" g: Boiler and Pressure Vessel Code,Section XI,1977 Edition through the jgj a
Summer 1978 addenda, and industry standards.
ih erg The examinations were perfomed by technicians qualified to Level I under the direct supervision of personnel qualified to Level II in accordance ig with Procedure 151-24. The data was evaluated by personnel qualified to 5 :gx a minimum of Level IIA in accordance with Procedure ISI-24.
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. . . . , e.-o EDDY CURRENT REPORT FOR 'c^u =^ no m m
...... ., , , , , DAVIS BESSE, UNIT 1 - AUGUST 1986 3"*- 1166319 A -0 A .e. n - .o
nse b. [_ THE BABCOCK & WILCOX COMPANY Serial No. 1-715 POWER GENERATION GR3UP Attichment i
M Two bobbin-coil exams and an 8x1 exam were conducted in each generator.
The primary bobbin-coil exam was for defect analysis. The second bobbin-coil exam was for defect analysis, as well as to determine the gap between the periphery and the auxillary feedwater header. The 8x1 exam go; was for inspecting the lane region where high cycle fatigue cracking has sg* been observed in OTSGs. The 8x1 probe was also used to further g08 characterize indications identified with the bobbin coil, aW!
I"! A small number of tubes were also re-examined with a magnetic bias, l3; bobbin-coil probe to suppress permeability variation signals.
3 8 .!
- r5 The Micro-TUBAN data management system was used for data tracking and 2(( reporting during analysis.
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,y 4.0 RESULTS 6
g; Tables 1, 2, and 3 summarize the results found during the inspections.
It is important to note that some tubes had more than one indication.
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"B" were removed from service.
! g, 5.0 ADDITIONAL COMMENTS
- z sc The "B" steam generator was examined first. With the exception of one indication of greater than 40% TW, nothing of unusual significance occurred. Equipment was removed from this generator and the one tube ig (75-62) was plugged. The "A" steam generator eddy current began near the
>- completion of the "B" steam generator eddy current. The lane / wedge
{8 region was inspected first, as had been done in the "B"'OTSG. When the 6*. random sample was begun in "A" 0TSG, a large number of indications 3!
og between tube support plates (TSPs) in the center of the generator was
, gg noted. Also, during visual observations of the interior of the "A" steam
- y. . generator, a turbulence was noticed in the water near the periphery.
R$5 Using this information, an additional sample was chosen for inspection.
o!! One portion of the sample contained the periphery area and one the 5!j central region. The periphery area was examined with no unusual indications. The central region, however, revealed a large number of 8;g Qie indications. It was decided to expand this sample in an attempt to
"!! contain these indications. The indications near the center of the 2
j,i generator were contained after the additional expanded sample by 3 2: surrounding tubes containing no detectable tube degradation.
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W* :I Due to the large number of indications localized in one area of the "A" EEI generator, a decision was made by the engineering group of Davis Besse to re-examine additional tubes in the central region of the "B" generator to
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,2 determine if it had similar indications. The additional "B" generator sample revealed nothing unusual in the central generator area.
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A4098 Page 3 LUDY CURRENI REPORI POR .e a .n 09/Z4/81 DAVIS BESSE, UNIT 1 - AUGUST 1986 o .a 1166319 ^- 0
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. ;,5o-l h,p _ THE BABCOCK & WILCOX COMPANY Serial No. 1-715 p;WER GENERATION GROUP Attachmgt i
The indications observed in the central area of "A" generator were usually multiple, small amplitude signals within a couple of inches along the tube length, however, some were as large as the flat bottom holes in the calibration standard. The 8x1 results showed that the indications doe were observed with only one or two adjacent coils. Usually, the same jg{ coil observed numerous flaws along the tube longitudinal axis.
f After leaving Davis Besse, a decision was made to analyze the reportable 5"! defect tubes for debris in the defect areas of the "A" generator.
NE: Debris analysis was done in an effort to determine a probable cause for Eg] this concentration of defects. The results of this analysis are included
- -5 in Appendix 1 of this summary, a:-
h!U8 Tubesheet maps, data sheets, and pertinent information to this exam are
.r contained in the following pages of this report.
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,,, ,, ,,,., EDDY CURRENT REPORT FOR .e Au DAv. 09/24/8f DAVIS BESSE, UNIT 1 - AUGUST 1986 omwo. 1166319 A*
0 PASSED ev APPg NO.
FORM '80M 1007 Ad
Docket No. 50-346 License No. NPF-3 THE BABCOCK & WILCOX COMPANY Serial No. 1-715
- POWER GENERATICN GRCUP Attachment l
Table 1. Summary of EC Inspection Results, Davis Besse - iugust,1986 ,
I*I A-0TSG B-0TSG 3wa "yj Bobbin 2$ Tubes Insp. 2648 2424
! Qty >40% 17 1
![5!y Qty 20-39% 30 0 s Qty <20 43 19 ej{ Qty S/N 288 14 CR*
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2 Tubes Insp. 130 102 n$
[ Qty >40% 0 0
!! Qty 20-39% 0 0
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=I Qty <20% 1 0 Qty S/N 3 2 G#
.z E" Saturation
- Tubes Insp. 16 l'0
,, Qty ->40% 0 0 Qty 20-39% 0 0
- I f Qty <20% 0 0 lE
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o!E *These do not include indications identified with the bobbin coil.
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. . . . , em EDDY CURRENT REPORT FOR .cne can 09/24/8f
...... ,, .,,, DAVIS BESSE, UNIT 1 - AUGUST 1986 0"*- 1166319 A. O A . . . . . . . . . .
1 I
L Docket No. 50-346 License No. NPF-3 THE BABCOCK & WILCOX COMPANY Serial No. 1-715 POWER GENERATION GROUP
, Attachment i
Table 2. Indications of 20% TW or Greater, Davis Besse - OTSG "A" AUGUST 1986 tab l I jg 8 R0W COL IND %TW LOCATION INCHES COMMENTS 38i
,./ 68 67 ODI 21 4TH TSP 10.50 5"W ! ODI 40 4TH TSP 11.00 PLUGGED ll!
2 8 J, g ODI 46 4TH TSP 11.70
=; 70 69 ODI 35 4TH TSP 26.20 y: ODI 34 4TH TSP 27.90
- E ODI 47 4TH TSP 28.40 PLUGGED
!! ODI 58 4TH TSP 28.90 j$
ODI 45 4TH TSP 30.50 j ODI 37 o) 70 70 70 75 ODI 27 4TH TSP 16.90 4TH TSP 8.00 PLUGGED 71 63 ODI 30 STH TSP 6.40 l
, , , ODI 29 STH TSP 8.90 PLUGGED
>2 001 38 STH TSP 10.20 ia ODI 33 STH TSP 11.30 S#
'i U!* 71 71 ODI 33 4TH TSP 6.00 PLUGGED gg ODI 33 4TH TSP 6.80 3.
t E !:i 73 52 ODI 51 6TH TSP -1.40 PLUGGED o3[E g[i 73 62 ODI 20 6TH TSP 9.00 8; ODI 27 6TH TSP 7.30
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"lj 74 62 ODI 25 7TH TSP 5.30 5;
3e: 75 54 IDI 37 10TH TSP 14.10 g::
Es2 75 65 ODI 40 7TH TSP -0.70 PLUGGED E30 gjp 78 65 ODI 23 7TH TSP 8.50 "I
- jo.!u ODI 29 7TH TSP 15.50 Nf(f i
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A4098 l Page 6 om av c ro EUDY GURRENI REPORT FOR .cate o.v. 09/24/8f
,,,,,, ,, ,_ DAVIS BESSE, UNIT 1 - AUGUST 1986 o,-a. 1166319 0
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Docket No. 50-346 License No. NPF-3 THE BABCOCK & WILCOX COMPANY Serial No. 1-715 POWER GENERATION GROUP Attachment
.t NO Table 2. Indications of 20% TW or Greater, Davis Besse - OTSG "A"'
AUGUST 1986 dos jg 8 R0W COL IND %TW LOCATION INCHES COMMENTS 88 lgi 82 64 ODI 35 STH TSP 16.10 PLUGGED goa ij$ 82 66 ODI 43 STH TSP 3.20 2a] ODI 35 STH TSP 24.00 PLUGGED
==5 ODI 27 6TH TSP 3.30 09: ODI 36 6TH TSP 3.30 iEE
.;8 82 69 ODI 45 4TH TSP 23.70 PLUGGED e%
y: 83 65 ODI 30 UTSF 5.60
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!i 83 67 ODI 36 3RD TSP 32.30 PLUGGED l$ ODI 59 4TH TSP 5.60
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e 84 63 ODI 46 3RD TSP 26.30 PLUGGED 85 64 ODI 56 3RD TSP 10.80 PLUGGED ODI 32 3RD TSP 22.00
..'a 2 85 65 ODI 22 4TH TSP -3.00 PLUGGED g; ODI 50 4TH TSP 8.60 2 *.
g! 85 70 ODI 59 4TH TSP 10.20 o6 ODI 49 4TH TSP 10.60 PLUGGED n ODI 34 4TH TSP 11.00 a=
'4 ! 141 68 ODI 24 8TH TSP -1.50
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((5 151 8 ODI 24 13TH TSP 3 2 ::
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I' A4098 Page 7
,, ,, ,, EDDY CURRENT REPORT FOR .e t. o.1, 09/Z4/8(
DAVIS BESSE, UNIT 1 - AUGUST 1986 o .... 1166319 A*
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Docket No. 50-346 License No. NPF-3 THE BABCOCK & WILCOX COMPANY Serial No. 1-715 POWER GENERATION GROUP Attachment
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Table 3. Indications of 20% or Greater, Davis Besse - OTSG "B" AUGUST 1986 dos 5w5 ou. R0W COL IND %TW LOCATION INCHES COMMENTS lUNyi 75 62 ODI 41 9TH TSP 2.80 PLUGGED i"
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ow= or e so LUUY GURHLNI MLFUKl tVK .c at, o.r. 09/24/dl DAVIS BESSE, UNIT 1 - AUGUST 1986 ...o 1166319 0 passeo er apro no. A5
DocketEo.SQ-346 THE BABCOCK & WILCOX COMPANY
' License No. NPF-3 Serial No. 1-715 PCWER GENERATION CROUP Attachment n
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Appendix 1 Eddy-Current Debris Analysis, Davis Besse, Unit 1 OTSG"A", August 1986
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$wo g$$ The results of the eddy-current examination of the Davis Besse, Unit 1 OTSG"A",
.! revealed a large concentration of wall-loss indications in a number of tubes located near the center of the generator. The great majority of these g{/! 2g indications were found between the third and eight tube support with the
- 3 .8, greatest concentration being located between the fourth and fifth tube support.
- 5 Concern over the gravity and origin of these indications led to a request for a ej{ debris analysis for all tubes containing degradation equal to or greater than gga twenty percent through-wall.
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e; The debris analysis was performed in accordance with procedure ISI-462. The i} entire length of each tube was examined for indications of debris or deposit.
- g At the customer's request, no sludge height measurements on the secondary side
[3 of the upper and lower tubesheets were made.
$5
- This method using the 35 kHz absolute signal is only sensitive to non-uniform gg quantities of debris. Uniform plating of debris over an extended length of 2 tubing is not detectable with this method.
3
- Results
.. Attachment I lists all debris indications for tubes with degradation >20% TW.
>2 These debris indications appear to be caused by magnetite collections at and E3 around the tube-to-support plate junction. There was no deposit or debris a :i detected on the free-span portions of these tubes. None of the debris found Uj seemed to indicate anything unusual .
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4 A4098 Page 9 LUUY LUKKLNI KLPUKl PUK .eus o.v. 09/Z4/81 DAVIS BESSE, UNIT 1 - AUGUST 1986 ..-. 1166319 0
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Docket No. 50-346 License No. NPF-3 THE BABCOCK Q WILCOX COMPANY 1-715
[,1"c POWER GENERATION GROUP n$
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Attachment 1
- 53 ; Debris Data Sheets, Davis Besse - August,1986
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. ! REEL lTO{ REEL' l DATE l 2, a :
i i !25__j09/09/861 EEi l:_ jA ! INLET _ l3 '
- 32 !'DFVIS BESSE
'ID' ROW lCOLVOLTSlDEGl% i
'CHel LOCATION l EXTENT
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FL EE! '
ISML 5 STH TSP + 0.0 e!
A[63l67 A 70 i 67 I 'SML 5 9TH TSP + 0.0 FL t a A 70' 69 SML 5 9TH TSP + 0.0 FL ss A 71 63 SML 5 9TH TSP + 0.0 FL
!5 A 78 65 NDD FL
- A 82 66 NDD FL 68 69 I NDD FL
[ 8 A 5 STH TSP + 0.0 FL A 70 70 SML e*! 71 NDD FL A 71 A 70 75 SML 5 STH TSP + 0.0 FL A 73 52 NDD FL a
s A 73 62 SML 5 15TH TSP + 0.0 FL FL n'8 A A
75 74 54 62 !
NDD NDD FL 2
33 A 82 64 SML GTH TSP + 0.0 FL "A MED 15TH TSP + 0.0 FL 5: A 83 65 . SML ISTH TSP + 0.0 FL Un . A 84 63 NDD FL 8$5 A 82 69 SML 5 STH TSP + 0.0 FL 51-
!! A 83 Ai 85 67 64 NDD tNDD FL FL 8: I . A' 85 65, NDD FL hl,2 *A 85. 70' 88' 67 NDD NDD FL FL
,, g ! A 87 66 NDD FL E: i A .
FL 3 2: .
A.14: 68 l c l9 1 iS!: S; !
lNDD SML 4 6TH TSP + 0.0 FL g[2,j i : ! i , ,
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A' A4098 page 10 i 1
EDDY CURRENT REPORT FOR .e.t. o v. 09/24/66 l DAVIS BESSE, UNIT 1 - AUGUST 1986 o-o. 1166319 A-0
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