ML20055A396
| ML20055A396 | |
| Person / Time | |
|---|---|
| Site: | McGuire  |
| Issue date: | 07/13/1982 |
| From: | Parker W DUKE POWER CO. |
| To: | Adensam E, Harold Denton Office of Nuclear Reactor Regulation |
| References | |
| NUDOCS 8207160251 | |
| Download: ML20055A396 (2) | |
Text
_ _ _ _.
DUKE POWEH COMPMY f
Powzu 11cumswo 422 SouTu Curucu SturzT, CuratorTE, N. C. asau f
l WI LLf AM O. PA R R E R, JR.
SC, Pett<Druf TEkt**0ht; Aeta 704 Snow Poocaction July 13, 1982 27> oes i
Mr. Harold R. Denton, Director Office of Nucicar Reactor Regulation j
U. S. Nucicar Regulatory Commission Washington, D. C. 20555 Attention:
Ms. E. G. Adensam, Chief l
Licensing Branch No. 4 Re: McGuire Nuclear Station Docket No. 50-369
(
Dear Mr. Denton:
On June 23, 1982 McGuire Nuclear Station Unit 1 was shut down after 720 hours0.00833 days <br />0.2 hours <br />0.00119 weeks <br />2.7396e-4 months <br /> of I
operation at 75 percent power. Eddy current testing (ECT) of all steam generators was started on June 28, 1982 and was completed July 3, 1982.
1 Results of the ECT indicate that some small additional wear occurred during the 1
j last period of operation at 75 percent power. Preliminary evaluation of the j
ECT data reveals the following indications:
"A" Steam Generator Indications were observed on 15 tubes. Maximum depth was approximately 15 percent. Affected tubes are the same tubes which showed distorted support j
plate signals during the previous ECT in March, 1982.
l "B" Steam Generator l
No indications.
"C" Steam Generator Eight indications observed on 6 tubes. The largest indication was on tube R49C 40.
This tube previously had an indication called < 20 percent.
The indication has grown to approximately 23 percent which is consistent with wear rate estimates submitted in the March 16, 1982 letter to the
'fhC))Lf Staff on this subject.
"D" Steam Generator No indications.
Dr. Cass Dodd, NRC consultant from Oak Ridge National Laboratories, was present during the evaluations of the ECT data and concurs in the above preliminary results.
8207160251 820713 PDR ADOCK 05000369 P
Mr. Harald R. Denton, Director July 13, 1982 Page 2 One tube in the "A" steam generator was plugged based on preliminary evaluation of the differential ECT data. This evaluation indicated 46 percent through wall wear.
It was suspected that this was an over-estimation of the wear,but rather than wait until final evaluation of the absolute ECT data, the decision was made to plug the tube to avoid schedule delay.
Duke Power Company is presently evaluating the ECT data in detail in order to determine a plan for the next period of operation. While this plan is being formulated and the ECT data are being evaluated, we have concluded that the plant can be operated at 50 percent power with no deleterious effect on the steam generator tubes due to fretting wear. This conclusion is based on the following:
- 1) Results of ECT conducted after operation at 50 percent power which revealed no detectable tube degradation (November 1981).
- 2) Results of ECT conducted at Almaraz after 1500 hours0.0174 days <br />0.417 hours <br />0.00248 weeks <br />5.7075e-4 months <br /> at 50 percent power which revealed no significant tube wear.
It is our intention to submit a detailed report describing the results of the June,1982 ECT by July 30, 1982. We believe that cperation at 50 percent power in the interim is prudent pending final evaluation of the ECT.
This plan is con-tingent upon resolution of the thermal sleeve problem.
Please advise if you have questions regarding this matter.
Very truly yours, "rk O. P William O. Parker, Jr.
NM GAC/php cc:
Mr. James P. O'Reilly, Regional Administrator U. S. Nuclear Regulatory Commission Renton II lot Marietta Street, Suite 3100 Atlanta, Georgia 30303 l
Mr. P. R. Bemis Senior Resident Inspector McGuire Nuclear Station
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