ML20086L188
| ML20086L188 | |
| Person / Time | |
|---|---|
| Site: | Sequoyah  |
| Issue date: | 12/09/1991 |
| From: | Joshua Wilson TENNESSEE VALLEY AUTHORITY |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| Shared Package | |
| ML20086L191 | List: |
| References | |
| NUDOCS 9112160087 | |
| Download: ML20086L188 (2) | |
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anAAA AAd, W mN e h x m r,aUrom k.o em J L W uon we nesent t %me taur ne December 9, 1991 U.S. Nuclear Regulatory Commission ATTN:
Docament Control Desk Washington,ED.C.
20555 3entlemen:
In the Mct:er of
)
Docket No. 50-327 Tennessee Valley Authority
)
SEGUGYAH VUCLEAR PLANT (SQN) - UNIT 1 - SPECIAL REPORT ON STEAM GENERATGR (5/G) ACTIVIT!ES COMPLETED DURING THE UNIT l CYCLE 5 REFUELING QUTAGE
Reference:
IVA letter to NRC dated Jecember 2, ~1991 "Special Report on Steam Generator (SG) Tube Inspections That Fall Into Category C-3" In accordance with-the requirements of the SQN Unit 1 Technical
- Specification (TS) paragraphs 4.4.5.5(a), (b), and (c), and as requested by the NRC staff November 19, 1991, enclosed is a report including the number of tubes plugged in each S/G the results of the S/G tubes in-service inspection completed November 24.-1991, the results of investigations conducted to determine the cause of the SQN L' nit 1 S/G tube deg.adation, and corrective measures taken to prevent recurrence.
An in-service inspection was performed on approximately 30 percent'of the tubes in each S/G.
The in-service inspection results (defined in IS 4.4.5.2) were classified as Category C-2 for S/Gs 1, 2, and 3.
S/G 4 was classified as Category C-3 because of the detection of primary water stress corrosion cracking (PWSCC) at the explosively expanded top-of-tubesheet expansion. zone'of thi tubes. The TVA reference letter provided notification of the Category C-3.
Because of the detection of expansion zone PWSCC, rotating pancake coil examinations were completed on 100. percent of the tubes in all four S/Gs.
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U.S. Nuclear Regulatory Commission
'Page 21 Dect.nber 9, 1991 To help prevent recurrence of expansion transition PWSCC in the SQN S/Gs, TVA took the conservative and proactive corrective action of the
-first-time implementation of shotpeening explosively expanded tubes b
during the Cycle 5 refuelin6 outage.
. Please direct questions-concerning this issue to D. V. Goodin at (615) 843-7734 Sincerely.
5 /N
)L. Wilson Enclosure cc (Enclosure):
Mr. D. : E. -LaBarge, Project Manager U.S. Nuclear Regulatory Commission One White Flint, North 11555 Rockville Pike Rockville, Maryland 10352 NRC Resident Inspectar i
LSequoyah Nuclear Plant
-2600 Igon Ferry Road Soddy Daisy. Tennessee 37379 7tr. B. A. Wilson.-Project Chief U.S. Nuclear Regulatory Commission Region II 101 Marietta Street, NW, Suite 2900 r
Atlanta.1 Georgia ~30323 L
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