RC-98-0051, Submits Response to GL 97-06, Degradation of Steam Generator Internals
| ML20216J567 | |
| Person / Time | |
|---|---|
| Site: | Summer  |
| Issue date: | 03/19/1998 |
| From: | Gabe Taylor SOUTH CAROLINA ELECTRIC & GAS CO. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| GL-97-06, GL-97-6, RC-98-0051, RC-98-51, NUDOCS 9803230491 | |
| Download: ML20216J567 (4) | |
Text
South C:.r: lina Electric & Cas Company Gary J. Taylor P.O. Box 88 Vica PrIsident Jenkinsville, SC 29065 Nuclear Operations
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(803) 345-4344 SCE&G Ascasacomperiy March 19, 1998 RC-98-0051 Document Control Desk U.
S.
Nuclear Regulatory Commission Washington, DC 20555-0001 Gentlemen:
Subject:
VIRGIL C.
SUMMER NUCLEAR STATION (VCSNS)
DOCKET NO. 50/395 OPERATING LICENSE NO. NPF-12 RESPONSE TO GENERIC LETTER 97-06
" DEGRADATION OF STEAM GENERATOR INTERNALS" Pursuant to your request, South Carolina Electric & Gas Company (SCE&G) is submitting the attached response under oath of affirmation.
Should you have any questions, please call Mr. Jeffrey Pease, at (803) 345-4124.
Very truly yours, H
L Gary lor JWP/GJT Attachment
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J.L.Skolds J.B.Knotts Jr.
W.F.Conway R.B.
Clary R.R.Mahan (w/o attachment)
M.F.Miltner R.J. White NSRC L.A.Reyes File (815.14)
L.M.Padovan RTS (LTR970005)
NRC Resident Inspector DMS 9803230491 980319 PDR ADOCK 05000395 gp7Q" f,/y P
Document Control Cen.erletter
' RC-98-0051 L'Ilt 970006 Page 2 of 2 STATE OF SOUTH' CAROLINA TO WIT COUNTY OF FAIRFIELD I hereby certify that on the
/f dayofA%u[
1998, before me, the subscriber, a Notary Public of the State of South Carolina personally appeared Gary J.
Taylor, being. duly sworn, and states that he is Vice President, Nuclear Operations of the South Carolina Electric & Gas Company, a corporation of the State of South Carolina, that he provides the foregoing response for the purposes therein set forth, that the statements made are true and correct to the best of his knowledge, information, and belief, and that he was authorized to provide the response on b'ehalf of said Corporation.
WITNESS my Hand and Notarial Seal
. a. [e
[g otary Public
-My Commission Expires July 26, 2005 Date s"
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tett:r to NRC Document Control Desk ATTACHMENT I RC-98-0051
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LTR970006 Page 1 of 2 Steam Generator Inspection Techniques The V. C. Summer Station replaced it's original Westinghouse model D-3 oteam generators in November 1994 with Westinghouse model Delta 75 Oteam generators.
The tubing and secondary side component material characteristics of the replacement steam generators is much improved
.over the original units.
The tubing is manufactured from Thermally Treated Inconal 690 and all secondary side materials are stainless steel.
The tube support plate design incorporates the tri-foil (3 lands) broached tube hole design in lieu of a drilled hole design found in the original units.
These characteristics have reduced the susceptibility to known damage mechanisms and enhanced the reliability of the steam generators overall.
To date no damage mechanisms have been identified by foreign or domestic utilities, that have Inconel 690 thermally treated steam generators tubes and/or using stainless steel secondary side components.
At VCS the steam generator tubing is examined in accordance with 1
Technical Specification requirements utilizing approved inspection techniques, as delineated in the EPRI Steam Generator Tube Ewamination Guidelines.
The methodology employed for the acquisition and analysis of this data ensures that anomalies identified using conventional bobbin coil techniques are further examined using a motorized rotating coil probe technology.
This includes support plate signals which are characterized as distorted.
To date no indications have been reported in any of the three steam generators.
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During the 9" refueling outage (Spring 1996) a visual examination was performed of the secondary side of the steam generators.
This included a walk down of the moisture separator areas and remote visual examination of the upper tube bundle and support plates.
No abnormalities were identified, all examinations reported a " clean" secondary side and no structures / components were identified as being degraded or defective.
The Delta 75 steam generators incorporate a oludge collector tray to assist in capture of impurities from the feed
. water system.
An inspection of this area indicated minimal sludge deposition (approximately 3/16" ) which was removed prior to steam generator close-out during the outage.
The minimal sludge findings are consistent with the operating history of the VCS steam generators.
Historically VCS has maintained good secondary side chemistry control and when coupled with the feedwater system de-aerator tank the sludge cccumulation has always been very low.
,. t.ptter to NRC Document Control Desk ATTACHMENT I RC-98-0051 LTR970006 Page 2 of 2 Currently, another secondary side examination is scheduled for the next refueling outage, RF-11 (Spring 1999).
The scope of this inspection will include all areas examined previously and will also include a tube I
bundle examination using remote visual techniques at several tube J
bundle elevations, including the top of the tube sheet.
l The steam generator inspection program is currently being revised to
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incorporate section 3.7 of EPRI Steam Generator Tube Inspection l
Guidelines and will include a schedule for future primary and secondary i
side examinations.
The program will define the techniques to be used
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for both primary side tube ewaminations and secondary side visual cxaminations in accordance with applicable industry guidance.
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