ML20004C604
| ML20004C604 | |
| Person / Time | |
|---|---|
| Site: | Sequoyah  |
| Issue date: | 05/29/1981 |
| 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 8106040318 | |
| Download: ML20004C604 (3) | |
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s 400 Chestnut Street Tower II May 29, 1981 SQRD-50-328/81-02 Mr. James P.
'Reilly, Director Office of Ins tien and Enforoenent U.S. Nuclear R atory r - i== ion Region II - Suite 100 101 Marietta Street Atlanta, Georgia 30 3
Dear Mr. O'Reilly:
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% -< g SEQUDYAH NUCLEAR PLANT UNIT 2 - FILLET WELD HISSPECIFICATION -
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SQRD-50-328/81 FOURTH INTERIM REPORT The subject deficiency was initially reported to NRC-OIE Inspector ',,'N y#
.g 10, 1980, in accordance with 10 CFR 50.55(eys N Q
R. W. Wright on December a
Interim reports were submitted en January 9, March Q~iTg ih/
and April 9, 1981. Enclosed is our fourth interia report. We expect to
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submit our next mport on or about June 22, 1981.
If you have any questions, please get in touch with D. L. Lambert at FTS 857-2581.
Very truly yours, TENNESSEE VALLEY AUTHORITY e
L. M. Mills, Manager Nuolear Regulation and Safety i
l Enclosure Mr. Victor Stallo, Director (Encicoure[
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Office of Inspection and Enforcement U.S. Nuolear Regulatory Cosmission Washington, DC 20555 30/7
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1 81060.403 W r
l ENCLOSURE SEQUOYAH NUCLEAR PLANT UNIT 2 FILLET WELD MISSPECIFICATION SKEWED TEE JOINTS SQRD-50-328/81-02 10 CFR 50.55(e)
FOURTH IKTERIM REPORT Description of Condition Our investigation har identified violations on the 135 degree maximum, 60 degree minimum angle permitted for intersecting members of prequalified fillet-welded skewed tee joints. For the Sequoyah Nuclear Plant (SQN), this requirement is imposed by the American Institute of Steel Construction (AISC) specification and the America Welding Society (AWS) D1.1 structural welding code.
This condition was found to exist in miscellaneous Category I steel features and for Category I mechanical and electrical component supports. The 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 T7A and vendor designs.
Interim Progress 1.
All drawings of the steel civil features were reviewed for presence of the nonconforming geometry. These features include cable tray supports, platforms, pipe-rupture protective devices, monorails, and tank and equipment supports. These structures are located in the auxiliary, control, reactor, diesel generator, and CO, at. rage buildings. From all civil structures, approximately 100 rt presentative nonconforming joints were selected for detailed structural analysis. In all cases evaluated, the joints were found to be stressed within allowable values. This analysis was conservative in that it either neglected the load-carrying capacity of the fillet weld in the acute and obtuse angle portions 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 impaired by specification of acute angles less than allowed by the design codes.
2.
The review of approximately 1,500 typical mechanical support drawings for conduit, instrumentation, ducts, and alternately l
analyzed piping two inches and under is complete. The nonconforming joints identif,ied numbered 169. All were evaluated using the procedure discussed in paragraph 1 above and all were found to be structurally adequate.
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3 Review is complete of the approximately 7,500 drawings of engineering pipe supports to identify locations of nonconforming joint geometry. The systems reviewed and number of drawings of nonconforming supports found in each are as follows:
A.
Reactor Coolant - 45 B.
Residual Heat Removal - 1 C.
Safety Injection - 51 D.
Chemical and Volume Control - 27 E.
Auxiliary Feedwater - 3 F.
Main steam - 5 G.
Component Cooling - 78 H.
Main Feedwater - 3 I.
Upper ilead Injection - 5 J.
Containment Spray - 35 K.
Steam Generator Blowdown - 15 L.
Essential Raw Cooling Water - 24 For the engineered pipe supports,176 representative supports were subjected to detailed structural analysis using the assumptions described in paragraph 1 above. All unit 2 pipe supports evaluated were found to be stressed within allowable values.
4.
Except for drawings furnished under our NSSS contract, TVA has completed identification and evaluation of TVA and vendor drawings involving gates, cranes, locks, doors, hatches, screens, bulkheads, seals, platforms, and engineered pipe supports not previously evaluated. Evaluation methods and criteria were as discussed above for,other civil and mechanical features. We anticipate review of the NSSS drawings will be completed before fuel load.
5.
Regarding the joints not yet reviewed, any nonconforming skewed tee joints which are found by analysis to be structurally inadequate will either have ths adequacy established by other methods or will be repaired.
6.
Engineers and designers have been alerted to the AISC/AWS requirements for limiting angles for skewed tee join'ts.
Instructions are presently being developed to provide additional design information.
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