ML20041B502
| ML20041B502 | |
| Person / Time | |
|---|---|
| Site: | Summer  |
| Issue date: | 02/19/1982 |
| From: | Nichols T SOUTH CAROLINA ELECTRIC & GAS CO. |
| To: | Harold Denton Office of Nuclear Reactor Regulation |
| References | |
| NUDOCS 8202240146 | |
| Download: ML20041B502 (4) | |
Text
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i SOUTH CAROLINA ELECTRIC & GAS COMPANY POST OFFICE BOA 784 N
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T. C. NicHoLs, J R.
February 19, 1982 8
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Mr. Harold R. Denton, Director
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Office of Nuclear Reactor Regulation U. S. Nuclear Regulatory Carmission Washington, D. C.
20555
Subject:
Virgil C. Sunmer Nuclear Station Docket No. 50/395 Westinghouse Model D-3 Steam Generators
Dear Mr. Denton:
On January 22, 1982, South Carolina Electric and Gas (bmpany (SC!%G) received Mr. D. G. Eisenhut's January 20, 1982 letter requesting a response within thirty days regarding plants to address probl es associated with the preheater section of Westinghouse Model D steam generators. SCE&G's present plan is providM in this letter.
Se Virgil C. Sunmer Nuclear Station utilizes three (3)
Westinghouse Rdel D-3 steam generators. We Model D-3 incorporates a split flow design where feedwater flow enters at a mid section of the geheater section and splits into an upaard and downward flow around the tubes ard baffles.
l We tube wear mechanism was first identified in the Model D-3 i
steam generator preheater area at a non-dcmestic plant. After 113 effective full power days of operation, this plant experienced a l
primary to secondary leak in one tube in the preheater section.
Inspections reveals 1 wear on other tubes in the outer three rows in
/
g00 this area.
Another non-<kmestic plant which had a similar operating history J
l fourd similar indications but of less magnitude.
//
SCE&G is aware of other operating plants having Model D-2 and D-4 steam generators, ard are followiO their progress as they proceed l
through their startup testing and operation.
As follow-up to previous meetings and frequent telephone discussions, SCE&G met with Westinghouse on Bebruary 10, 1982 to discuss the nature of the mechanisms observed. We discussed with Westinghouse the gogram that is in place to understand the nature of the phencmena to permit operation of all preheat steam generators.
me Westinghouse pogram includes the use of scale nodel testing, 8202240146 820219 PDR ADOCK 05000395 A
PDR t
Mr. Harold R. Denton Ebbruary 19, 1982 Page 2 analytical studies, wear testing, pericxlic eddy current inspction of operatirg units and the use of diagnostic internal and external instrumentation in selected operating plants.
As stated, installation of internal accelemeters has been used by Westinghouse as a diagnostic tool for verification of the analytical studies and concurrent lab testing. At the present tine, diagnostic internal instruentation is installed or being installed in a Model D-2 unit domestic plant and in Model D-3 and D-4 in non-domestic plants. Field data collection frm the diagnostic instrumentation has adequately met the verification needs of the Westinghouse evaluation gogram and the diverse type Mxlel D units instrumented makes it unnecessary to further instrurent Model D units at this time, merefore, Westinghouse has concluded that in-plant, on-line, data availability is not needed for safe operation of the Virgil C. Sumer Nuclear. W e m nclusion for not installing internal instrumentation at Virgil C. Smmer Nuclear Station is based on the following:
- 1) The similarities with the nxiel D-3 unit currently instrumented and the adequacy of diagncstic instrument data currently collected.
- 2) The results to date of the Westinghousa evaluation gogram including analyses, lab testing and operation plant data, support the start-up gogram ard safe level of pwer operation defined below.
In our review of the Westinghouse gogram, we have determined that the results of the Westinghouse anaylsis and test programs and the experience and data gained frm these two operating plants appear to be adequate. Accordingly, our current program is outlined below:
(bnduct normal low power testing.
(bnduct power escalation testing up to 50% power to cmplete the startup testing up to and including that level.
Continue operation at 50% power for approximately 2 nonths or at a pwer level above 50% that has been evaluated, based upon information available at that time, to preclude significant tube damage.
Shut down and eddy current test rows 49, 48, and 47 of one steam generator.
1
Mr. Harold R. Denton February 19, 1982 Page 3 Reevaluate available data to confirm continued limited pywer operation capability until a modification can be accmplished to resolve the goblem.
The proposed schedule may be altered at any time to perform modifications.
Following cmpletion of this phase of the program SG&G ard Westinghouse will jointly establish an operating pmr level for operation of the Virgil C. Sumer Nuclear StJtion prior to mcdification. In determining this power level consideration will be given to:
Results of the eddy current inspection.
The experience and data fr m other operating plants.
The status of the Westinghouse analysis and test Irogram.
The status of any proposed Westinghouse modification to alleviate or resolve the gobim.
In sumary SCE&G has reviewed the Westinghouse program to approach this problem and will goceed vith the outline of activities as describal above. Additional details and scheduling information will be Favided to the NRC as they becme available.
If you have any questions, please let us kim.
Very truly yours, a
T. C. Nichols, Jr.
RBC:'ICN:lkb cc: Page 4
Mr. Harold R. Denton Ebbruary 19, 1982 Page 4 cc:
V. C. Sunrner T. C. Nichols, Jr.
G. H. Fischer H. N. Cyrus H. T. Rahh D. A. Natsnan M. B. Wt11 taker, Jr.
W. A. Williams, Jr.
O. S. Bradham R. B. Clary M. N. Browne A. R. Koon G. J. Braddick J. L. Skolds J. B. Knotts, Jr.
B. A. Bursey C. L. Ligon (NSRC)
J. C. Ruoff J. P. O'Reilly H. Grossman F. F. Hooper G. A. Linenburger J. B. Cbokinham R. R. Mahan NPCF File
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