ML20079B150
| ML20079B150 | |
| Person / Time | |
|---|---|
| Site: | Sequoyah  |
| Issue date: | 06/11/1991 |
| From: | Wallace E TENNESSEE VALLEY AUTHORITY |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| TAC-59457, NUDOCS 9106140019 | |
| Download: ML20079B150 (3) | |
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.,a w~ c.,~., u n n hhk U.S. Nuclear Regulatory Commission ATTN:
Document Control Desk Washington, D.C.
20555 Gentlemen:
In the Hotter of
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Docket No. 50-347 Tennessee Valley Authority SEQUOYAll NUCLEAR PLANT (SQN) - TVA RESPONSE TO NRC SAFETY EVA1.UATION REPORT (SER) CONCERWl' C SQN'S UNIT 1 10-YEAR IN-SERVICE INSPECTION (ISI)
PROGRAM Referenco:
NRC letter to TVA dated Februnry 7,1991. "First 10-Year Interv61 Inservico Inspection program (TAC 59457) - Sequoyah Nuclear plant. Unit 1" By the referenced letter, NRP provided thu SER for SQN's Unit 1 10-Year ISI. TVA has completed ' s review of the subject. SER and has identified one area of concern.
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concern pertains to TVA's request for rollet (RFR) ISI-4 and involves the lower-cono transition circumferential choll wold on the steam generator (SG) secondary side.
NRC evaluation of TVA's RFR was included in the technical evaluation report (TER) attached to the referenced SER (pages 3.' and 33).
This evaluation acknowledges that the lower-cone transition wold is partially inaccessible because of a permanent support ring and pads on tach SG.
American Srciety of Mechanical Engineers (ASME). Section Kl. requires that 100 percent of one of those wolds from one SG be examined each inspection interval.
As a result of t1o ASME,Section XI, code requirement and the wold being partially inaccessible, the TER " concluded that relief from the Code requirements of a volumetric examination of the above mentioned steam generator circumferential shell wolds should be granted, provided that the wolds from other steam generators be volumetrically examined to the extent that tha total examination on the steam generator wolds equals 100% of one wold required to be examined."
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U.S. Nuclear Regulatory Commission JUN 11199; TVA requests that the original proposed alternativo examination of FFR 181-4 as submitted by TVA be granted without the additional examinations as concluded in the TE:R. TVA considers this approach to be justifled based on the following:
There is a smc11 probability of weld f ailure based on history.
- Approximately 68 porcent of the wold is volumotrically examined.
The wold volumo examined is r. paced around the S0 circumfereneo and is well distributed. TVA corss 3ers this weld volume to be adequate f or detection of problems suci* as cracking, please note that the witMrawal of this requirement for the additional examination will allow consistency with the Unit 2 ISI program previously approved by NRC.
This request has been discussed with NHC technical staff.
It is requestod that NHC's responso ho provided by July 31, 1991, to support the scheduling of outato activities for the Unit 1 Cycle 5 refueling outago.
This outage is currently scheduled to begin October 4, 1991.
please direct questions concerning this issue to D. V. Goodin at (615) 843-1734.
Very truly yours.
TENNESSEE VALLEY AUTH0H1TY
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E. C. kil o,
ager Nuclear Licensing and Regulatory Affairs cc:
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3 U.S. Nuclear Reguintory Connission cc Ms. S. C. Black, Deputy tairector Project Directorate 11-4 U.S. Nuclear Regulatory Coumission Ono White Flint, North 11555 Rockvillo Piko Rockville, Maryland 20852 Mr. D. E. LaBargo, Project Manager U.S. Nuclear Regulatory Commission one White Filnt, North 11555 Rockvillo Piko Rockville, Maryland 20852 NRC Resident Inspector Sequoyah Nuclear Plant 2600 Igou Ferry Road Soddy Daisy Tennensco 37379 Mr. B. A. Wilson, Project Chief U.S. Nuclear Regulatory Commission Region 11 101 Marietta Street. IIW, Suite 2900 Atlanta, Georg a 30323 i
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