ML20078N858
| ML20078N858 | |
| Person / Time | |
|---|---|
| Site: | Farley  |
| Issue date: | 02/03/1995 |
| From: | Dennis Morey SOUTHERN NUCLEAR OPERATING CO. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| NUDOCS 9502160156 | |
| Download: ML20078N858 (2) | |
Text
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Southern Nuebar Operzting Company Post Offica Box 1295 Birmingham. Alabama 35201 i
Telephone (205) 868-5131 j
e oei. uor.y Southem Nudear Operating Company Vice President t
Farley Project the Southem electHC System i
February 3, 1995 t
Docket Nos.:
50-348 I
50-364 I
U.S. Nuclear Regulatory Commission ATTN.: Document Control Desk Washington,D.C. 20555 j
Joseph M. Farley Nuclear Plant WM aabar Allov 600 Steam Generator MWaical Tube Pluas i
i Gentlemen:
The following status is provided as requested by the NRC Staffin response to recent field experience with Westinghouse Alloy 600 Dermally Treated (Tf) mechanical plugs. This letter serves to provide the Staff with our intended response to this latest field data.
In December 1994, WM nahase notified us of recent field experience with Alloy 600 mechanical plugs l
i that necessitated a revision to the corrosion algorithm presented in WCAP-12244, Revision 3. His i
revision in the corrosion algorithm affects our previously developed schedule and action plan for j
addressing all remaining Alloy 600 TT mechanical plugs in our steam generators. Westinghouse issued i
Addendum 3 to WCAP-12244, Revision 3, on January 25,1995. De original basis for a Justification i
of Continued Operation provided to us by Westinghouse continues to apply until appropriate actions l
can be taken. We believe that the issue is being effectively managed by the industry and that the issue i
does not pose an immediate safety concern to the health and welfare of the public.
l At present, Farley Unit I has a total of 47 Westmghouse Alloy 600 Tf mechanical plugs in senice in j
l our steam generators which have not been repaired. Of the total population, there are 10 hot leg plugs and 37 cold leg plugs. Of these, a total of 6 cold leg plugs are present in tubes where plug top release may lead to tube perforation. The 10 hot leg plugs will be removed in the upcoming Fall 1995 outage, e
Under the most conservative microstructure factor assumptions, the earliest a cold leg plug requires replacement is 2002 for Unit 1. All cold leg Alloy 600 mechanical plugs will be replaced prior to the cnd of their conservatively estimated life.
At present, Faricy Unit 2 has a total of 62 Westinghouse Alloy 6001T mechanical plugs in senice in our steam generators which have not been repaired. Of the total population, there are no hot leg plugs j
and 62 cold leg plugs. Of these, a total of 5 cold leg plugs are present in tubes where plug top release p
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may lead to tube perforation. Under the most conservative microstructure factor assumptions, the M
l carliest a cold leg plug requires replacement is 2004 for Unit 2. All cold leg Alloy 600 mechanical I
plugs will be replaced prior to the end of their conservatively estimated life.
21 0156 950203 60 p
DOCK 05000343 AUUUOU
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l U. S. Nuclear Regulatory Commission Page 2 Continued safe operation of Farley Units I and 2 is assured. De basis of acceptability for continued operation is the validation of the previously developed JCO presented in Section 3.0 of WCAP-12244, Revision 3. Based on a current review of the plant configuration and operating conditions, we have concluded that the JCO is applicable to Farley Unit I during the time period when the plug calculated repair / replacement dates are exW and the next scheduled refueling outage.
I De bases for the JCO are summarized below:
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- 1. Low probability of a plug top release (PTR) event.
- 2. The population of tubes which may perforate as a result of PTR is limited.
- 3. Should perforation occur, the primary-to-secondary leakage consequences are limited.
- 4. There is a low likelihood that multiple plugs could be in a condition that would be capable of resulting in PTR.
- 5. De plant Emergency Response Guidelines are adequate to bring the plant to a safe shutdown condition.
Our actions above are consistent with the action plan defmed in NRC Bulletin 89-01 and its supplements. This action plan applies only to Alloy 600 'IT @=nical plugs. Repaired or welded j
plugs are not affected.
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As stated earlier, all Alloy 600 hot leg plugs will be removed from the Farley units following completion of the Unit 1, Fall 1995 outage. All Alloy 600 cold leg plugs will be replaced prior to the end of their
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conservatively estimated life.
If you have any questions, please advise.
i Respectfully submitted, SOUTHERN NUCLEAR OPERATING COMPANY
$f 1]un Dave Morey REM /citTLUGNRC. DOC cc:
Mr. S. D. Ebnete:
Mr. B. L. Siegel Mr. T. M. Ross Mr. T. A. Reed s.
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