ML20003E882
| ML20003E882 | |
| Person / Time | |
|---|---|
| Site: | Sequoyah  |
| Issue date: | 04/09/1981 |
| From: | Mills L TENNESSEE VALLEY AUTHORITY |
| To: | James O'Reilly NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II) |
| References | |
| 10CFR-050.55E, 10CFR-50.55E, SQRD-50-328-81, NUDOCS 8104170436 | |
| Download: ML20003E882 (2) | |
Text
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TENNESSEE VALLEY AU'rHCR f TY 300'C$iitiiut Etie"e"t"To'3eI8 II
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SQRD-50-328/81-02 April 9, 1981
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Mr. James P. O'Reilly, Director N
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U.S. Nuclear Regulatory Commission d * %"'88*%*
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Dear Mr. O'Reilly.
SEQUOYAH NUCLEAR PLANT UNIT 2 - FILLET WELD MISSPECIFICATION -
SQRD-50 S?8/81 THIRD INTERIM REPORT The subject deficiency was initially reported to NRC-0IE Inspector R. W.
Wright on December 10, 1980, in accordance with 10 CFR 50.55(e) as NCR SQN SWP 8025. Interim reports were submitted cn January 9, and March 3,1981.
Enclosed is our third interim report. We expect to submit our next report by May 29, 1981.
If you have any questions concerning this matter, please get in touch with D. L. Lambert at ETS 857-2581.
Very truly yours, i
TENNESSEE VALLEY AUTHORITY L. M. Mills, Manager Nuclear Regulation and Safety Enclosure
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Mr. Victor Stello, Jr., Director (Enclosure) V Office of Inspection and Enforcement U.S. Nuclear Regulatory Comnission Washington, DC 20555 Ol$
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ENCD3SURE SEQUOYAH NUCLFAR PIANT UNIT 2 FILIEf WEID MISSPECIFICATICN SQRD-50-328/81-02 10CFR50.55(e)
'IHIRD INTERIM REPORP Descriotion of Condition our investigation has identified violations of the 135 degree maximum, 60 degree minimum angle permitted for intersecting members of fillet-welded skewed tee joints. For the Sequoyah Nuclear Plant (SON), this requirement is imposed by the American Institute of Steel Construction (AISC) specification and the American Welding Society (ANS) Dl.1 structural welding code.
his condition was found to exist in miscellaneous category I ateel features and for category I mechanical and electrical cmponent supports. Se category I buildings are not involved in the nonconformance since none of these structures are steel framed.
Further investigation has also identified this condition in engineered pipe supports in the intake and essential raw cooling water pumping stations and in gates, cranes, locks, doors, hatches, and other miscellaneous mechanical features in both '1VA and vendor designs.
Interim Procress All drawings of the steel civil features were reviewed for presence of the nonconforming gemetry. B ese features include cable tray supports, platforms, pipe-rupture protective devices, monorails, and tank and equipnent supports. Rese structures are located in the auxiliary, control, ceactor, diesel generator, and CO,3 storage buildings. For all civil structures, approximately 100 representative nonconforming joints were selected for detailed stmetural analysis.
In all cases evaluated, the joi *.s were found to be stressed within allowable values. mis analysis was conservative in that it either neglected the load-carrying capacity of the fillet weld in the acute a.d cbtusc angle pcrtions of all joints, or only considered a portion of the weld throat as structurally effective. TVA concludes that the structural integrity of these joints was not inpaired by specification of acute angles less than allowed by the design codes.
Se review of approximately 1500 typical mechanical support drawings for conduit, instrumentation, ducts, and alternately analyzed piping 2 inches and under is complete. We nonconforming joints identified numbered 169. All were evaluated using the procedure discussed above and all were found to be structurally adequate.
N
. Paview is complete of the approximately 7500 drawings of engineered pipe supports to identify locations of nonconforming joint geometry.
The systems reviewed and number of nonconforming supports found in each are as follows:
A.
Reactor coolant - 45 G.
Canponent cooling - 78 B.
Residual heat removal - 1 H.
Main feedwater - 3 C.
Safety injection - 51 I.
Upper head injection - 5 D.
Chemical and volume control - 27 J.
Containment spray - 35 E.
Auxiliary feedwater - 3 K.
Steam generator blowdown - 15 F.
Main steam - 5 L.
Essential raw cooling water - 24 Analysis of these nonconforming joints is underway using the assumptions described in paragraph 1 above.
IVA will evaluate nonconforming weld joints occurring on both TVA and vendor drawings involving gates, cranes, locks, doors, hatches, screens, bulkheads, seals, platforms, and engineered pipe supports not yet evaluated. Evaluation methods and criteria will be as discussed above for other civil and mechanical features.
Regarding the joints not yet reviewed, any nonconforming skewed tee joints which are found by analysis to be structurally inadequate will either have the adequacy established by other methods or will be repaired.
Engineers and designers have been alerted to the AISC/AWS requirements for limiting angles for skewed tee joints. Instructions are presently being developed to provide additional design information.
With the review and analysis of SQN drawings near 50 percent complete, there is no indication that the subject nonconformance could in any way interfere with or impair the ability to load fuel at SON unit 2.
The review, analysis, and any necessary repair, rework, or reevaluation will be cx:rnpleted uefore initial critica'ity.
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