ML20082V235
| ML20082V235 | |
| Person / Time | |
|---|---|
| Site: | McGuire, Mcguire  |
| Issue date: | 12/14/1983 |
| From: | Tucker H DUKE POWER CO. |
| To: | Adensam E, Harold Denton Office of Nuclear Reactor Regulation |
| References | |
| NUDOCS 8312200032 | |
| Download: ML20082V235 (2) | |
Text
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e DUKE POWER GOMPANY P.O. HOX 33180 CHARLOTTE, N.C. 28242 HALltTUCKER ret.zenown vics r=**so==r (704) 373-4531
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December 14, 1983 Mr. Harold R. Denton, Director Office of Nuclear Reactor Regulation U. S. Nuclear Regulatory Commission Washington, D. C. 20555 Attention:
Ms. E. G. Adensam, Chief Licensing Branch No. 4 Re: McGuire Nuclear Station Docket Nos. 50-369, 50-370
Dear Mr. Denton:
The McGuire Nuclear Station - Unit 2 Facility Operating License, NPF-17, contains Condition No. 2.C. (4) which states :
"By December 31, 1983, the licensee shall provide, for NRC ' staff review and approval, justification for continued operation with the seven thermal sleeves removed from selected locations in the reactor coolant system."
The purpose of this letter is to provide the justification required by the license condition. Although the license condition only applies to Unit 2, the discussion and justification apply to both Units 1 and 2.
This subject was discussed with the NRC staff in a meeting on July 13, 1982.
In addition to justifying interim operation of McGuire - Unit 1 with a missing thermal sleeve, a commitment to remove the remaining thermal sleeves was made.
For Unit 2, the seven thermal sleeves of concern were removed prior to initial fuel loading, whereas on Unit 1 the remaining thermal sleeves were removed during the outage commencing in January 1983.
On January 27, 1983 a meeting was held between Westinghouse and the NRC staff to discuss resolution of the overall thermal sleeve issue including justifica-tion for unit operation with thermal sleeves removed. The pertinent conclusions presented by Westinghouse at this meeting were:
- 1) The thermal sleeve attachment weld cracks and subsequent thermal sleeve migration are limited to " generation 3" thermal sleeves used only in reactor coolant loop branch nozzles of a butt weld design.(McGuire is classified as a " generation 3" plant).
- 2) Sleeve attachment weld cracking was caused by high cycle fatigue due to flow induced vibration.
- 3) For nozzles with thermal sleeves not in place, nozzle integrity is assured for design basis transients.
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Mr. Harold R. Denton, Director December 14, 1983 Page 2
- 4) For the phenomena of thermal cycling due to flow mixing between the branch line and the reactor coolant loop, nozzle integrity was demonstrated using conservative fatigue analysis.
In response to a request by the NRC staff, Westinghouse provided additional information on design transients and their effect on reactor coolant loop nozzles (
Reference:
Letter E. P. Rahe, Westinghouse to E. H. Vollmer, NFC,
" Design Transients Related to Thermal Sleeve Removal", dated May 9,1983).
The conclusions in this letter were:
- 1) None of the branch nozzles in the reactor coolant system is subjected to a large temperature difference between its respective branch line and the reactor coolant system, and
- 2) The cyclic stresses induced by the postulated high cycle thermal transients in the nozzle would not contribute to nozzle fatigue.
Duke has reviewed this information and concludes that McGuire Nuclear Station can be operated safely with the seven affected thermal sleeves removed from Units 1 and 2.
Accordingly, License Condition No. 2.C.(4) is satisfied.
Please advise if there are further questions regarding this matter.
Very truly yours, x[+dL s
Hal B. Tucker GAC/php cc:
Mr. W. T. Orders NRC Resident Inspector McGuire Nuclear Station Mr. James P. O'Reilly, Regional Administrator U. S. Nuclear Regulatory Commission Region 11 101 Marietta Street, NW, Suite 2900 Atlanta, Georgia 30303