ML20049J499

Final Deficiency Rept Re Fillet Weld Misspec,Initially Reported 801210.General Const Spec G-29C Revised to Clarify Const Requirements for Skewed T-joints.Info Emphasizing Aisc/Aws Requirements Will Be Issued by 820401

ML20049J499
Person / Time
Site:	Yellow Creek
Issue date:	03/01/1982
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, NUDOCS 8203180278
Download: ML20049J499 (3)

Text

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. , b TEtJNESSEE VALLEY AUTHORITY . ,[ A, .

CHATTANOOGA. TENNESSEE 37401 3 /Ojj 400 Chestnut Street Tower II //jp ' 'S; March 1, 1982 4/8. Si.

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U.S. Nuclear Regulatory Commission NN 9 Region II Attn: Mr. James P. O'Reilly, Regional Administrator -jnn,[,{d, 1.3, ^ ydfig 17 79,2 l 101 Marietta Street, Suite 3100 Q i4rs , j /

Atlanta, Georgia 30303 ';/;, .

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Dear Mr. O'Reilly:

YELLOW CREEK NUCLEAR PLANT UNITS 1 AND 2 - FILLET WELD MISSPECIFICATION -

YCRD-50-566/81-01 AND YCRD-50-567/81 FINAL 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 YCN YCP 8006. This was followed by our interim reports dated January 9, April 8, August 12, and December 4, 1981. Enclosed is our final report. This deficiency has also been reported for Sequoyah, Watts Bar, Bellefonte, Hartsville, and Phipps Bend Nuclear Plants as NCRs SQN SWP 8025, WBN SWP 8008, WBN ^907R, BLN BLP 8007, HTA HPP 8003, HTB HPP 8003, and PBN HPP 8003 If you have any questions concerning this matter, please get in touch with R. H. Shell at FTS 858-2688.

Very truly yours, TENNESSEE VALLEY AUTHORITY 1

L. M. Mills, Manager Nuclear Regulation and Safety Enclosure oc: Mr. Richard C. DeYoung, Director (Enclosure)

Office of Inspection and Enforcement U.S. Nuclear Regulatory Commission Washington, DC 20555

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s ENCLOSURE YELLOW CREEK NUCLEAR PLANT UNITS 1 AND 2 FILLET WELD MISSPECl?ICATION YCRD-566/81-01 AND YCRD-567/81-01 10 CFR 50.55(e)

FINAL REPORT DESCRIPTION OF DEFICIENCY Our investigation has identified violations of the 135-decree maximum, 60-degree minimum angle permitted for intersecting members of prequalified fillet-welded skewed T-joints. For the Yellow Creek Nuclear Plant, this requirement is imposed by the American Institute of Steel Construction

( AISC) specification and the Amer-ican Welding Society (AWS) D1.1 structural welding code.

The violations occurred because designers were unaware of the requirements -

of the AWS structural welding code governing angularity limits and weld symbols for fillet welded skewed T-joints.

SAFETY IMPLICATIONS In any of the analyzed cases, had the initial specifications used proved to be inadequate, the ability of the structure involved to withstand design loads without excessive deformation could have been impaired. This situation could have resulted in a degradation of the safe operation of the plant.

CORRECTIVE ACTION TVA has completed a review of all TVA and vendor designs which are governed by the AISC specification and AWS structural welding code. The results of this review are as follows:

1. Violations of the angle limitations were found to occur on TVA drawings of handrail and bracing connections in the Intake and Essential Raw Cooling Water Pumping Stations and on vendor furnished instrument racks. The instrument racks were seismically qualified by an actual test. In the other cases, the joints were evaluated and 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 other than allowed by the design codes.

2. Fillet weld misspecification was found to occur on one TVA civil drawing showing stanGard details for platform supports and on four TVA civil drawings involving stairs, platforms, and handrails in the Control Building. These drawings were corrected and reissued in the time period between February 17, 1981, and May 11, 1981.

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G V Page 2 3 Fillet weld misspecification was identified on some AISC/AWS designs appearing on the design drawings prepared by CB&I under the containment design contract. These drawings had been issued but no welding had been performed. CB&I has completed a design review of all nonconforming welds. Where overstress occurred, joints were redesigned and details on design drawings were changed to conform to the new design. The design review, redesign, and drawing changes have been reviewed and approved by TVA.

4. On all Combustion Engineering supplied equipment fabricated to the requirements of the AISC specification, the subject welds have either been qualified by analyses or are considered nonload carrying welds.

5. TVA's YCNP project mechanical, electrical, and support d)2ign groups have no acute angle welds shown on thsir design drawings that are in nonconformance with AWS or AISC. -

To prevent recurrence of this condition, general construction specification G-29C has been revised to clarify construction requirements for skewed T-joints. Information will be provided to all engineers and designers further emphasizing the AISC/AWS requirements for fillet welded skewed T-joints. TVA anticipates issuing this information by April 1,1982.

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