ML20079N932
| ML20079N932 | |
| Person / Time | |
|---|---|
| Site: | Summer  |
| Issue date: | 01/27/1984 |
| From: | Dixon O SOUTH CAROLINA ELECTRIC & GAS CO. |
| To: | Harold Denton Office of Nuclear Reactor Regulation |
| References | |
| NUDOCS 8401310022 | |
| Download: ML20079N932 (5) | |
Text
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SOUTH CAROLINA ELECTRIC & GAS COMPANY POST OFFeCE 764 COLUMetA. south CAmoWNA 29218 O. W. DixoN. Jft, January 27, 1984 v.Ce m.,oo.'
NUCLEAN Opt #Af*oNS Mr. Harold R. Denton, Director Ofiica of Nuclear Reactor Regulation U.S. Nuclear Regulatory Commission Washington, D.C.
20555
Subject:
Virgil C. Summer Nuclear Station i
Docket No. 50/395 Operating License No. NPF-12 Model D-3 Steam Generator Inspection
Dear Mr. Denton:
In response to the letter from the Nuclear Regulatory Cammission (NRC) dated December 27, 1983, the following informaticn concerning the Model D-3 Steam Generator Inspection performed in April 1983 at the Virgil C.
Summer Nuclear 3tation is provided:
Item 1 - Eddy Current Results A multifrequency eddy current examination was performed on the preheater section of three (3) steam generators at the Virgil C.
Summer Nuclear Station.
The inspection was performed in accordance with ASME XI, 1974 Edition, 1975 Addenda, 1977 Edition through Summer 1978 and NRC Regulatory Guide 1.83, Rev. 1, dated July 1975.
The specific tubes inspected were rows 45 through 49, all columns in each steam generator.
The examination frequencies were 550 KHZ and 130 KHZ differential, and 300 KHZ and 100 KHZ absolute.
The 550 KHZ and 130 KHZ differential test frequencies were mixed together to reduce tube support signal interference.
The 300 KHZ and 100 KHZ absolute frequencies were also mixed together to reduce tube support signal interference.
The output mix of the 300 KHZ and 100 KHZ was used for detection of wear in the tube support plate regions.
The lower mix output (300 KHZ and 100 KHZ) was also used to help locate and evaluate any possible discontinuities in the "U" bend areas, and to assist in discontinuity evaluations in other areas.
8401310022 840127 FDR ADOCK 05000393 I
g G
PM g
I.
e Mr. Harold R. Denton Model D-3 Steam Generator Inspection January 27, 1964 Dage #2 The examination revealed that there were no tubes with discon-tinuities greater than or equal to 20% in any of the three (3) steam generator preheater sections.
The attachment provides a i
summary of results of this examination as compared to the previous baseline.
Item 2 - Manifold Visual Inspection Results for all Steam Gcnerators An examination was performed on the modified preheater inlet components of all three (3) steam generators at the Virgil C. Summer Nuclear Station as discussed in our letters to the Staff, dated February 14, 1983, and May 3, 1983.
The inspection was performed in compliance with ASME XI, 1977 Edition through Summer 1978 Article IWA-2211.
The results of the inspection were videotaped.
The three (3) major areas covered during this examination were (1) mechanical inspection (mating surface gaps, fasteners, locking clips, fretting / wear, erosion, corrosion), (2) weld inspection, and (3) sludge / deposit buildup and loose parts.
Access was gained through openings in the feedwater pipe located near the nozzles.
The fiberoptic scope was then moved to the areas of interest using a guide tube manufactured for that purpose.
The modification components of all three (3) steam generators were found to be free of defects, including fretting / wear, erosion, corrosion, cracks, sludge / deposits or loose parts.
Item 3 - Tube vibration Monitoring Results Tube vibration monitoring was performed during power escalation following the installation of the steam generator modification.
Westinghouse provided the 'results of the tube vibration monitoring progrcm in a subsequent report.- At that. time, Westinghouse identified the existence of a 20 H signal.that was believed to be g
electrical noise.
South Carolina Electric and Gas Company (SCE&G) requested that Westinghouse perform a further evaluation to determine the exact nature of the 20 Hz signal.
In October 1983, additional tube vibration monitoring was performed by Westinghouse.
The data collected during the monitoring are. presently being evaluated by Westinghouse.
The results of both the 20 Hz-evaluation and the additional vibration monitoring _ evaluation will represent an addendum to the initial report and are scheduled to be completed in February 1984.- When the addendum is received and reviewed, both the initial report-and the addendum will be forwarded t.o the NRC.
4
i Mr. Harold R.
Denton Model D-3 Steam Generator Inspection January 27, 1984 Page #3 9}
Item 4 - Inlet Pressure Monitoring Results The inlet pressure monitoring was performed during startup after the installation of the steam generator modification.
Subsequent evaluation of the data by Westinghouse and SCE&G led to a questioning of the validity of this data.
During the recent eddy current outage, the inlet pressure monitoring instrumentation was checked and found to be incorrectly installed.
The installation problems were corrected, and the inlet pressure monitoring was repeated during startup after the oatage.
Westinghouse is evaluating the results of the inlet pressure monitoring, and has indicated that a final report will be available by the end of April 1984.
Upon receipt and review of the final report by SCE&G, the report will be forwarded to the NRC.
Should there be any questions, please contact us at your convenience.
Ver truly yours,
/
l
/
O. W.
D on, Jr WRM:MNB:PVF:OWD/fjc
Attachment:
cc:
V.
C.
Summer T.
C. Nichols, Jr./O. W.
Dixon, Jr.
E.
H.
Crews, Jr.
E.
C.
Roberts W.
A.
Williams, Jr.
D.
A.
Nauman J.
P.
O'Reilly Group Managers O.
S.
Bradham C.
A.
Price C. L. Ligon (NSRC)
G.
J.
Braddick D. J.
Richards NRC Resident Inspector J.
B.
Knotts, Jr.
NPCF File
w f
ATTACHMENT Steam Generator A
- Tubes Examined:
292 Area Examined:
Full length from inlet side Rows 45 through 49 all columns.
Results from Subject Examination:
No change.
Baseline results (Spring 83):
Tnree (3) tubes less than 20% OD.
Row Column Location 49 40
+.3 inches above 14th support outlet side.
47 48
-19 inches below 13th support outlet side.
48 77 at the 5th support outlet side.
- Tubes Examined:
294 Area Examined:
Full length from inlet side Rows 45 through 49, all columns.
Results from Subject Examination:
No change.
Baseline Results (Spring 83):
Two (2) tubes less than 20% OD.
Row Column Location 49 64 at 6th support outlet side.
49 75 at 8th support outlet side.
- Tubes examined:
292 Area Examined:
Full lenoth from inlet side Rows 45 through 49 all columns.
Results of Inspection (Fall 83) :
No changes detected.
Baseline Results (Spring 83):
No indications.
Attachment Page #2 General Tubes listed below were found to have undefined signals during this inspection.
The signals are distinct characteristics indicating outside diameter origination with low percentage i
through wall signal spans of one to several inches in length detectable in the lower mix range.
Steam Generator A Row Column Location 47 50
-3 inches below 8th support plate to +3 inches above the 8th support plate inlet side.
46 55
+2.5 inches above 8th support outlet side.
46 59
+3 inches above 8th support outlet side.
49 69
+8 inches above 8th support outlet side.
49 72
-3 inches below 9th support outlet side.
45 62
+2 inches above lith support outlet side.
46 44
+5 inches above 8th support plate inlet side.
46 47
+5 inches above 8th support plate outlet side.
Steam Generator B No undefined signals during inspection of the preheater section.
Steam Generator C No undefined signals during inspection of the preheater section.
4