ML17254A269
| ML17254A269 | |
| Person / Time | |
|---|---|
| Site: | Ginna  |
| Issue date: | 03/18/1985 |
| From: | Kober R ROCHESTER GAS & ELECTRIC CORP. |
| To: | Zwolinski J Office of Nuclear Reactor Regulation |
| References | |
| NUDOCS 8503250203 | |
| Download: ML17254A269 (20) | |
Text
REGULATORY INFORMATION DISTRIBUTION SY iM (RIDS)
ACCESSION NBR:8503250203 DOC ~ DATE: 85/03/18 NOTARIZED:
NO DOCKET,'
FACIL:50 244 Robert Emmet Ginna Nuclear Plantg Unit li Rochester G
05000244 AUTH,NAME-AUTHOR AFFILIATION KOBERgR xiii Rochester Gas 8 Electric Corp.
RECIP ~ NAME RECIPIENT AFFILIATION ZNOLINSKIgJ,A ~
Operating Reactors Branch 5
SUBJECT:
Submits supplemental info to 850222 ltr re technique'or.
detecting tubesheet crevice corrosion 8 sleevesiper,850313 telcon w/NRC ~ NRC concurrence to proceed w/installation of up to 65 tubesheet sleeves in facility inlets requested, DISTRIBUTION CODE:
A001D COPIES RECEIVED:LTR ENCL SIZEi TITLE; OR Submittal:
General Distr ibution NOTES;NRR/DL/SEP 1cy OL!09/19/69 05000244 RECIPIENT ID CODE/NAME NRR ORB5 BC 01 INTERNAL: ACRS 09 ELD/HDS4 NRR/DL DIR NRR/DL/TSRG NRR/DSI/RAB RGN1 COPIES LTTR ENCL 7
7 6
6 1
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1 1
1 1
1 1
1 RECIPIENT ID CODE/NAME ADM/LFMB NRR/DE/MTEB NRR/DL/ORAB
. l, METB KEG F IL 04 COPIES LTTR ENCL 1
0 1
1 0
1 1"
1 1
EXTERNAL: LPDR NSIC NOTES; 03 05 1
1 1
1 1
NRC PDR 02 1
1 TOTAL NUMBER OF COPIES REQUIRED:
LTTR 27 ENCL 24
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8/SS USES IIIII I IIIIIWZ
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SSAlf ROCHESTER GAS AND ELECTRIC CORPORATION o 89 EAST AVENUE, ROCHESTER, N.Y. 14649-0001 ROGER W. KOBER VICE PRE SlDENT fLfCTRIC EI STEAM PROD VCTlON TfLEPHONE AREA CODE TIE 546-2700 March 18, 1985 Director of Nuclear Reactor Regulation Attention:
Mr. John A. Zwolinski, Chief Operating Reactors Branch No.
5 U.S. Nuclear Regulatory Commission Washington, D.C.
20555 a
Subject:
Ste'am Generator Tubesheet Crevice Corrosion and *Sleeves R.E. Ginna Nuclear Power Plant Docket No. 50-244
Dear Mr. Zwolinski:
This letter is a supplement to our letter dated February 22, 1985 on tubesheet sleeves and in response to questions from NRC staff during a conference call on Wednesday, March 13, 1985.
The Staff asked that we describe our technique for detecting tubesheet crevice corrosion and provide them with a list of crevice indications which would be sleeved during the present refueling and maintenance outage.
In order to provide Staff with Ginna's procedure for detecting crevice corrosion, an historical summary of Ginna's crevice corrosion experience is helpful to see how and when the present procedure was established.
During the March 1979.refueling and maintenance
- outage, two crevice corrosion indications were analyzed from the 400 KHz differential channel of the multi-frequency eddy current data.
These two indications were identified by both the ZETEC and Intercontrol analyst teams from their respective instruments and data.
This examination's results alerted Rochester Gas and Electric (RG&E) to be sensitive to the tube sheet crevice area of the steam generator during future inspections.
Another cause for concern was the experience of similar Westinghouse plants where crevice corrosion, specifically intergranular attack, was causing plant shutdowns due to primary to secondary leakage.
In December 1979, during an unscheduled
- outage, a large number of tubes were inspected across the center of the B-Steam Generator inlet (hot leg) where the original crevice indications had been seen in March.
This examination was performed utilizing a single frequency eddy current instrument operating at 400 KHz with differential coils.
Results from a significant number of tubes showed eleven more crevice indications in the same general area of the tube sheet.
Therefore, a multifrequency eddy current r
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ROCHESTER GAS AND ELECTRIC CORP.
DATE To Narch 18, 1985 Nr. John A. Zwolinski SHEET NO.
procedure was developed for use in the upcoming Spring 1980 outage with both absolute and differential coil techniques specified.
In April 1980, during the scheduled refueling and maintenance
- outage, while analyzing the multifrequency eddy current data from the B-Steam Generator a relationship between the differential frequency indications and the absolute frequency indications was noticed.
This relationship was based upon the fact. that when there was a differential frequency indication the absolute frequencies were showing a vertical drift through the same area of the tube sheet crevice.
It was further noticed that other tubes in close proximity to these indications had ~onl absolute frequency indications.
The technical evaluation of these indications was that differential frequency indications were caused by stress corrosion cracks within an area of intergranular attack.
It was suspected that.
the intergranular attack was being detected by the absolute frequencies over some axial length.
The postulated reason that the absolute frequencies were detecting the intergranular attack area and the differential frequencies were not, was that the depth of intergranular attack penetration gradually became
- deeper, maximized, and then gradually lessened to no penetration.
- Thus, geometry of corrosion would balance out on the differential
- coils, and not be detected.
Therefore, tubesheet crevices with only absolute frequency indications were under intergranular attack and did not contain a stress corrosion crack.
To confirm this theory, two hot leg tubes were removed in April 1980 from the B-Steam Generator, one with differential and absolute frequency indications, and one with only an absolute frequency indication.
The metallurgical analysis of these tubes showed that both tubes were degraded by intergranular attack.
The tube with a differential frequency indication also had a
stress corrosion crack penetration in front of the intergranular attack.
Therefore, the tube pull results confirmed that absolute frequency indications, with no differential indication, were indicative of intergranular attack alone.
The results of the examination of these tubes can be found in EPRI Report. NP-2534-LD dated August 1982.
Confirmation of the absolute technique detecting the minor conductivity loss associated with intergranular attack provided the basis for developing the absolute frequency mix of 200 KHz and 100 KHz.
This mix allows for the elimination of tubesheet and support plate interference signals as well as copper and other deposit signals for confirmation of true crevice indications.
This, coupled with the 400 KHz and 200 KHz differential mix, has been used since that time as the standard procedure for detecting crevice corrosion in the tube sheets of Ginna Station's steam generators.
I
ROCHESTER GAS AND ELECTRIC CORP.
DATE March 18, 1985 Nr. John A. Zwolinski SHEET NO.
Further verification of this procedure has been demonstrated by the removal of three tubes from the B-Steam Generator in 1981 and one more in 1983.
The results of the metallurgical analysis of these four tubes provided a very good correlation between the field eddy current analysis and the actual metallurgical condition.
The results of the examination of these tubes can be found in EPRI Reports NP-3070-LD dated May 1983 and NP-3731-LD dated September 1984.
Also, Ginna Station's steam generators have never experienced any primary to secondary leakage from crevice corrosion defects since the first two were called during the April 1979 Refueling and Maintenance Outage.
The following table provides an historical summary of Ginna's inspection results utilizing the above described multifrequency procedure.
GINNA'S STEAM GENERATORS CREVICE CORROSION INDICATION HISTORY B-Steam Generator A-Steam Generator March 1979 Not Sizeable 0-25%
26-50/
51-75/
76-100/
A-S/G TOTAL (o)
B-S/G TOTAL December 1979 April 1980 November 1980 April 1981 February 1982 October 1982 April 1983 March 1984 March 1985 19 27 ll(3) 3(1) 15 0(l) 0" (o)
(o)
(0)
(o)
(o) 7(1) 7 15 1
2 (4) 9(1) 27(1)
(2) 14 59 51 69 88 (3) 17 (1) 39 (1) 50 (2) 67 (1 (8) 261 On Friday, March 15, 1985 and Saturday March 16, 1985 the steam generator inlet (hot leg) inspection data was fully analyzed and given a complete second level review for the B-and A-Steam Generators, respectively.
These analyses resulted in 2 crevice corrosion indications in the A-Steam Generator and 69 crevice corrosion indications in the B-Steam Generator as tabulated above.
A listing of crevice indications and tubesheet maps
ROCHESTER GAS AND ELECTRIC CORP.
DATE To March 18, 1985 Mr. John A. Zwolinski SHEET NO.
showing their locations are included as Attachments I and II to this letter.
Attachment III is a description of the nomenclature used on the lists.
Presently the outlet (cold leg) inspections are proceeding with examination of all tubes to at least the first support, plate and approximately 30 percent of the tubes inspected full length
'n both steam generators.
ZETEC data analysts have interpreted approximately 70 percent. of the A-Steam Generator data and 40 percent of the B-Steam Generator data.
RGSE's second level review of the data is ongoing with approximately 25 percent of the data from both steam generators complete.
The results to
- date, require one tube in each steam generator to be plugged.
There is a defect in the U-bend area of the A-Steam Generator and a support plate wastage indication in the B-Steam Generator.
As was mentioned in our February 22 letter, and discussed with NRC Staff on March 15, corrective action for crevice corrosion indications would be brazed sleeves where there was accessibility for a 36 or 28 inch sleeve, and tubesheet sleeves in areas where accessibility of brazed sleeves is limited or where they would be beneficial from an ALARA standpoint.
At the time of our discussion with NRC Staff, we were planning on installing no more than 35 tubesheet sleeves as part of our corrective action plan for the B-Steam Generator.
- However, based upon technical problems that have developed while installing ten brazed sleeves in the B-Steam Generator, and the radiation exposure associated with this installation
As an alternative, tubesheet sleeves would allow for the
- repair, and maintaining inservice, of 56 tubes in the B-Steam Generator and 2 tubes in the A-Steam Generator with crevice indications.
Three other tubes in the B-Steam Generator would require plugging because there is minor intergranular attack indications near the location of the tube sheet sleeve upper explosive weld.
Attachment IV illustrates the position of the explosive weld relative to the secondary face of the tube sheet and provides the basis for the acceptability for the upper explosive weld to be made in that area of the tube sheet.
Although only 58 tubes have presently been identified for repair with tubesheet
- sleeves, RGM is requesting NRC concurrence to proceed with installation of up to 65 tubesheet sleeves in Ginna Station's steam generator inlets.
We believe this is acceptable based upon the discussion in our letter of February 22 and previous submittals on this subject.
truly yours, Attachments R@er W. Kober
j
PLANT GINNA STATION 3QZTACHMENT I-UNIT<
S/G LEG A
INLET REEL TO REEL DATE 10 03/12/85 SG RON COL LIST 11 021 072 11 021 040 01.33 042 099 1
HTS 00.78 094 072 1
HTS
-0017.3
-0017.3 TS 00077-11 Ts 00201-05 VOLTS DEG CH~ LOCATION REPAIR INDEX OF CREVICE If'lDICATIONS A S/G INLET 03 5 T IMOTH F.
St'JELL RGhE LEVEL II GARY L.
HENRY BABCOCK h NILCOX LEVEL II MANAGFR,MATERIALS ENGINEERING LEVEL III EXAMINER PAGE 01 OF Oi LIST OF DATA STORED ON DISK
is RGSE Steam Generator A Qreklce. Sndlca1-tdhf 9l 8P)8785&$ 1911157'571 L94765LEkl &957 55 535I49474545 41 3937 353331 29272523211917 15 1311 9 7 5 3 82 66 462 54 5254 464 3 36 'f323 IB 16 14 12 IO 4
2 COLUMNS
/arm Ately y/8'lf5 MANWAY
~
~
NOZZLE~
ROWS 42 41 38 36 3
32 3
30 2
28 26 25 2
22 21 20 17 15
'4 13 II IO 8
6 5
2-I ~
ATTACHMENT II PLANT GINNA STATION UNIT~
S/G LEG HOT REEL TO REEL DATE 03/15/85 SG RON COL VOLTS DEG CH4 LOCATION REPAIR INDEX FINAL LIST OF ZETEC AND RGhE CREVICE INDICATIONS 2
3 5
6 7
8 9
10 11 12 13 14
'15 16 17 18 19 20 21 22 2~4 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 42 9
9 4
8 15 29 2
38 30 18 19 13 2
30
)0 34 41 20 38 42 16 38 21 34 39
+7 I
16 9
29 31 13 24 27 19 30 30 1
21 23 34 23 34 5
6 12 16 19 28 29 32 33 34 34 34 35 36 36'8'9 39 40 41 42 42 43 44 45 47 48 48 49 4q 49 51 53 54 54 55 55 55 56 59 3.27
- 1. 91 1.57 1
37 2.12 2.30 32.20 2.65 2.05 1.50 1.61 1.52 69 73 169 139 77 95 56 70 82 155 98 85 4.76
- 19. 82 2.70 1,34 1.74 2.29 2.46 10.57 1.34 0.93 1.41 1.45 0.91 1.47 6.47 7.40 2.05 1.11 1.20 0.74 1.63 62 46 49 134 57 49 55 54 96 120 130 116 77 50 51 70 148 112 127 88 1.56 0.74 69 79 1.98 45 0,89 139 85 83
<20 33 83 68
>40 83 76
>40 95 40 92 96 93
>40 SQR 68 52 98 55 80
>40 SQR
>40 84 SQR 29 58 47 74 SQR SQR SQR 85 79 1
1 1
I M 2 1
1 1
1 1
1 1
M 2 M 2 1
HTS HTS HTS HTS HTS HTS HTS HTS HTS HTS HTS HTS HTS HTS HTS HTS HTS HTS HTS HTS HTS HTS HTS HTS HTS HTS HTS HTS HTS HTS HTS HTS HTS HTS HTS HTS HTS HTS HTS HTS HTS HTS HTS HTS HTS 18,3 17.8 17.4 17.9 18.5 15.4 17,6
. 18.4 17.8 13.1 7.8 6,1 16.5 18.3 9.1 18.7 18.8 11,1 18.4 18.3 5,8 9.9 18.0 8.7 18,3 17.4 17.2 17.6 18,4 5.2 17.8 7,1 17.3 9.2 17.8 18,1 15.2 17,4 17.8 18.5 4.9 12.0 17.6 13,4 17.9 TS TS TS TS TS TS TS TS BZ BZ PLUG TS TS TS
.BZ, TS TS TS'S TS BZ TS TS PLUG TS TS TS TS
, TS
'7..
TS lPg
,-TS'S BZ BZ BZ TS TS TS PLUG
,BZ TS TS TS 16-15 44-12 77-20 149-10 177-17 520-14 542-7 569-6 585-9 609-14 634-10 654-9 677-13 751-60 830-18 857-8 874-8 891 8 1027-9 1071-34 1118-12 1138-7 1153-7 1169-8 1192-14 1221-14 1284-48 1387-54 1457-15 1482-9 1509-17 1536-9 1553-7 1587-26 1640-26 1693-26 1728-8 1749-12 PAGE OF 2
LIST OF DATA STORED ON DISK
,(3AQH)
II "L l,,
3,q',q)
PLANT GINNA STATION UNITw S/G LEG HOT REEL TO REEL DATE 03/15/85 SG RON COL VOLTS DEG CH~ LOCATION REPAIR INDEX 43, 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 35 35 34 35 33 35 32 28 31 31 32 31 30 28 8
18 3
19 21 24 18 29 14 27 28 7
19 59 60 61 62 64 66 67 68 70 71 71 72 72 72 73 74 75 75 75 75 76 78 79 79 79 81 85 1.28 1.80 7.80 2,26 1.81 2.32 3.51 3.05 0.84 1,96 10.91 7.75 5,50 6.30 2.91 1,36 4.61 4.42 1.94 6.48 2.84 107 133 84 72 75 81 81 78 87 50 45 52 67 71 48 46 63 78 46 42 43 61 SQR 41
>40 83 DS DS SQR 81 78 78 79 74 95
>40
>40
>40
>40 SQR 95 96 88 80 96
>40 SQR 98 1
M 2 1
1 1
1 1
M 2 M 2 M 2 M 2 HTS HTS HTS HTS HTS HTS HTS HTS HTS HTS HTS HTS HTS HTS HTS HTS HTS HTS HTS HTS HTS HTS HTS HTS HTS HTS HTS 17.9 18.2 17,6 16.9 14.2 18.1 17.9
,8.8 16.9 16.8 18.1 17.6 17.6 17.7 14,3 17.5 17.8 16.3 17.8 17.8 15.6 18.1 16.6 18.4 17.8 17.1 18.2 TS TS
..TS TS TS TS TS
'S~
TS TS TS TS TS TS TS BZ TS TS TS TS TS TS TS TS TS TS TS 1769-7 1790-13 1817-13 1875-44 1948-28 2006-29 2065-29 2140-45 2201-15 2228-11
, 2252-12 2282-17 2312-12 2337-12 2374-24 2415-16 2448-16 2516-51 2591-23 2631-16 2673-25 2716-17 2754-20 2787-12 2812-12 2845-20 2886-20
+isJzs TODD A.
RICHARDS BABCOCK h WILCOX LEVEL III TIMOTHY SNELL RGhE LEVEL II Lyse+
5 le&
ALBERT CURTIS III MANAGER, MATERIALS ENGINEERING LEVEL III EXAMINER PAGE 2
OF 2
LIST OF DATA STORED ON DISK
C/
))
RGSE Steam Generator 8 %<<a'> C~~LeG)
I q) &8785838I191115757)L96765L361595755535)49474545 41 393735333) 29272523211917 15 13) I 9 7 5 3 I
COLUMNS
'92 9 88SL 82 8/74 2
462 5
525 0 4'424 3
3lo 2
18 16 14 12 IO 864 FIhAI /8 AP 3'll5/85'qoo)
~. MR.2K MANWAY
~
~
~
NOZZLE~
ROWS 4
4 42
)
40 38 36 4
32 33 31 30 28 26 23 22 21 20
)9 I
17 15
'4 12 I I IO 8
6 4
2
~
I
7 Attachment III Final List of ZETEC and RGSE Crevice Indication Nomenclature To of List Information SG - Number of the defect.
ROW - Row number from the tube identification.
COL - Column number from the tube identification.
VOLTS Amplitude of measured indication signal.
4' Perecent through wall from O.D. based on measured signal.
CH5 Channel from which indication was determined.
LOCATION - Location of crevice indication within the tubesheet.
REPAIR TS - Tubesheet sleeve; BZ-36" Brazed sleeve, Plug. BSW or CE plug INDEX - Location of tube data on magnetic tape.
Information under
'20 Measurable indication less than 20% through wall (IGA-SCC).
>40 Absolute indication measured from absolute mix where depth determination cannot be performed because there is not a calibration curve (IGA only).
SQR Multiple indications interferring with a depth determination (IGA-SCC).
DS Distorted roll transition indication that, cannot be confirmed or measured.
XX -
The measured percent, through wall of the deepest penetration (SCC) within an IGA patch or area.
'nformation Under CH5 1
Indication determined and measured with 400 KHz differential for final interpretation.
M2 Indication determined with absolute mix, depth cannot be accurately determined, but based upon amplitude is felt to be above 40% IGA.
Information Under LOCATION HTS Secondary face of tubesheet.
-XX.X Depth below the secondary face of the tubesheet where the indication is located.
O.
'4 H
p d
t 1I.
A. TACHNENT IV TUBESHEET SLEEVE UPPER END Before Explosive Weld After Explosive Weld Tube Top of Tubesheet 1'/4" g 2'/4" Tubesheet Sleeve Start of Sleeve
, Transition
! 3/4"
.3tt 4 3/4" I Approximate Start of Weld
'.75" Minimum Weld Length 3/4"
'End of Sleeve Transition'
'>Minimum Depth of Defect for. Installation of Tubesheet Sleeves
.