ML19256A933
| ML19256A933 | |
| Person / Time | |
|---|---|
| Site: | Browns Ferry  |
| Issue date: | 01/11/1979 |
| From: | Gilleland J TENNESSEE VALLEY AUTHORITY |
| To: | Ippolito T Office of Nuclear Reactor Regulation |
| References | |
| NUDOCS 7901170165 | |
| Download: ML19256A933 (1) | |
Text
TENNESSEE VALLEY AUTHORITY CHATTANOOGA. TENNESSEE 374o1 500C Chestnut Street Tower II JAN 111979 Director of Nuclear Reactor Regulation Attention:
Mr. Thomas A. Ippolito, Chief Branch No. 3 Division of Operating Reactors U.S. Nuclear Regulatory Commission Washington, DC 20555
Dear Mr. Ippolito:
In the Matter of the
)
Docket No. 50-259 Tennessee Valley Authority
)
In our January 9,1979, letter to you, TVA requested permission to change the plant procedures governing minimum bolt up temperature for the Browns Ferry unit 1 reactor vessel. The current technical specifications (3.6.A.5) allow tensioning of the bolting studs for a cold reactor condition only when the temperature of the vessel head flange and the head is greater than 100 F.
The basis for this temperature requirement results from the ASFE Code requirements to use NDT temperature plus 600F. The NDT temperature of the closure flanges, adjacent head and shell material, and stud material is a muimum of 40 F.
Therefore, the minimum bolt up temperature equals 0
100 F.
As a result of the concern about atypical weld material outlined in the August 14, 1978, letter from T. A. Ippolito to N. B. Uegies, TVA formulated a revised bolt up temperature based on maintaining a margin of safety equivalent to the original design, i.e., no atypical weld material present.
The analysis for the suspect weld material indicates an NDT temperature of 70 F would be conservative. Therefore, TVA proposed a minimum bolt up temperature of 130 F for the plant procedures until the issue is resolved.
TVA indicated in the January 9, 1979, letter to you that we believed the issue was resolved by a review of the records for the unit 1 vessel fabrication, and we proposed deletion of the 130 F temperature. Through discussions with your staff on January 10, 1979, we have agreed to maintain the 139 F minimum bolt up temperature for the closure flanges and the adjacent hes and shell material. However, since the 70 F NDT (1300F bolt up temperature) is determined only for material which may contain the suspect weld metal the bolting studs will meet the current technical specification requirement of 100 F based on the original NDT temperature of 400F.
0 We understand that your staff is continuing to investigate this matter with Babcock & Wilcox. Please let us know if we may assist you in this effort.
Very truly yours, 0
o)L
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l J. E. Gilleland WOugg Assistant Manager of Power An Equal Opportunity Employer