ML20062L274
| ML20062L274 | |
| Person / Time | |
|---|---|
| Site: | Hartsville  |
| Issue date: | 12/31/1980 |
| From: | Mills L TENNESSEE VALLEY AUTHORITY |
| To: | James O'Reilly NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II) |
| References | |
| REF-PT21-80-336-000 10CFR-050.55E, 10CFR-50.55E, NCR-HNP-A-091, NCR-HNP-A-91, NUDOCS 8101230718 | |
| Download: ML20062L274 (3) | |
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MC. Ar+ T.i Q O t3-w -c3e TENNESSEE VALLEY AUTHORITY
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CHATTANOOGA. TENNESSCC 374of 400 Chestnut Street Tower II
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December 31, 1980 Go-6it Mr. James P. O'Reilly, Director Office of Inspection and Enforcement U.S. Nuclear Regulatory Commission Region II - Suite 3100 101 Marietta Street Atlanta, Georgia 30303
Dear Mr. O'Reilly:
HARTSVILLE NUCLEAR PLANT UNIT A1 - REPORTABLE DEFICIE!!CY - CRACTS IN RPV SHIELD FALL (NCR HNP-A-091)
Initial notification of the subject deficiency was made to NRC-CIE, Rerion II, Inspector R. W. Wright on !! arch 11!, 1980.
The first, second, and third
'..terim reports were submitted en April 14, July 3, and October 3, 1080, retpectively.
In compliance kith paras:raph 50.55(e) of 10 CFE Part 50, enclosed is the final report en the subject deficiency. We censider 10 C R Party applicable to this nonconformance.
If ycu have cny questions concerning this subject, please call Jim Demer at FTS 657-2014.
Very truly yours, TE.! ESSEE VALLEY AUTHORITY
~
y P., Mills, Manager
!!uel gr Regulation and Safety Enclosura ec:
Mr. Victor Stello, Director (Encles Te)
Office of Inspection and Enforcement U.S. Nuclear Regulatory Co==ission Washinctor. DC 20555 An Ecual Opportunity Employer
ENCLOSURF HARTSVILLE UUCLEAR FLA!!! U"IT A1 CRACKS IN RPV SHIELD PALL 10 CFR50.55 (e)
NCR HNP-A-001 REPORT NO. 4 (FINAL)
On March 14, 1980, TVA informed NRC-0IE Region II inspector, R. W.
Wright, of a potentially reportable condition under 10 CFR 50.55(e) regarding cracks in the reactor pressure vessel (RPV) shield wall structure supplied by Industrial Engineering Works (IEW), Trenton, New Jersey.
This is the final report on this deficiency.
Descriotion of Deficienev During fabrication of the RPV shield wall, it was discovered that there were base netal cracks in the RPV shield wall inner shell plates.
One through-wall crack in the interior wall of tier No. 1 was approximately 13 inches long. A second crack on tier No. 1 at the edge of the removal area of the test sample which was examined by Singleton Laboratory was approximately 3-1/2 inches long. This was not a through-wall crack. The third crack was located in the interior wall of tier No. L and was approximately 12 inches icnc. Extensive examination of the structure has revealed no additional evidence of crackine.
The previously nentioned sample was sent to Singleton Materials Engineering Laboratory for analysis. Although factors sue 5 as the boren content (0.001o percent), welding stresses and possibly jacking stresses to correct distortion created during fabrication contributed to the failure, the exact cause of the cracking could not be established.
Propagation of the crack was by a brittle transgrarular s
cicavage mcde.
A horicental TVA fiele weld arrested the vertical growth of the crack.
No other conclusiens could be drawn frcm the test results.
Safety Irplications Cracks in the RPV shield wall could degrade its structural integrity to the point that it may not be able to adecuately perform its intended function which could adversely affect plant safety.
Corrective Action TVA has completed the repair of the shield wall structure using materials and procedures which have been approved by GE.
In order to minimice the chances of future cracking, TVA will implement the following:
1.
During all welding and thermal cutting, preheat will be maintained at 150 F mininu=. The preheat will be maintained without interruption until a minimum of 3/4 inch of weld metal is deposited.
2.
All future e.is.atch which ccnnot ba corrected by nornal construction practice, i.e. bull pire, weds;es, and nederate jackinc will be corrected by drat cutting and rewelding using full per.etration welds.
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