ML20069H068

Final Deficiency Rept Re Cracked Welds in Containment Annular Steel End Connections.Initially Reported on 820910. Metallurgical Investigation Performed,Welding & Installation Procedure Revised & Cracked Connections Replaced

ML20069H068
Person / Time
Site:	Seabrook
Issue date:	10/12/1982
From:	Devincentis J PUBLIC SERVICE CO. OF NEW HAMPSHIRE, YANKEE ATOMIC ELECTRIC CO.
To:	Starostecki R NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I)
References
10CFR-050.55E, 10CFR-50.55E, SBN-340, NUDOCS 8210190363
Download: ML20069H068 (3)

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Companyof New Hampshir e 1671 Worce6;er Road Framinohom, Massachusetts 01731 (6171 - 872 - 8100 October 12, 1982 SBN- 340 T.F. 02.2.2 United States Nuclear Regulatory Commission Region I 631 Park Avenue King of Prussia, PA 19406 Attention: Mr. Richard W. Starostecki, Director Division of Resident and Project Inspection

References:

(a) Construction Permit CPPR-135 and CPPR-136, Docket Nos. 50-443 and 50-444 (b) Telecon of September 10, 1982, A. L. Legendre (YAEC) to Eldon Brunner (NRC Region I)

Subject:

Final 10CFR50.55(e) Report; Cracked Welds in Containment Annular Steel End Connections

Dear Sir:

On September 10, 1982, a potentially reportable 10CFR50.55(e) item was reported [ Reference (b)] regarding cracked welds in the Unit 1 containment annular steel end connections.

It has been determined that this item is reportable under 10CFR50.55(e).

The following information is provided per 10CFR50.55(e)(3) and is considered to be the final report on this item.

Description of the Deficiency As reported in NCR 59/2731, field welded framing connections for sr 41 radial beams of the annulus steel frame of the containment structure we.

found to exhibit surface cracks at the toes of the full and partial penetration welds connecting vertical plates to attachment plates on the secondary shield walls. The vertical plates are located on both sides of each radial beam web and are bolted to it, forming the beam end connections.

Analysis of the Safety Implications A failure of these welds could result in the loss of the structural integrity of the annular steel frame, thus possibly affecting the functional capability of the safety-related systems supported by this frame.

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United States Nuclear Regulatory Commission October 12, 1982 Attention: Mr. Richard W. Starostecki Page 2 Corrective Action Taken

1. A metallurgical examination of a section from connection #3G1220A which exhibited a crack on the outside of the partial penetration joint was undertaken. The metallurgical investigation indicated that the defects were the result of lamellar tears in the ASTM A36 attachment (filler) plate caused by welding strains associated with the use of a restrained tee joint. A second connection #3G1226A was also removed and sectioned in the field. Similar defects were observed in the inside and outside surfaces of the full penetration and partial penetration joints re spectively.

2. All thirty-one (31) similarly detailed connections which had been installed up to the date of the NCR were reinspected for defects. The uninstalled connections were put on hold.

3. On the basis of the findings of the metallurgical investigation, the following changes have been initiated:

a. The use of " clean" ASTM A516 Gr 70 (Lukens Fineline) steel in lieu of ASTM A36 for the filler plate.

b. Revised welding procedure which requires weld bead deposition favoring the filler plate and a 2000F preheat.

c. Revised installation sequence to make the vertical welds to filler plate prior to welding the filler plate to the shield wall.

4. All previously installed connections have been rejected. A procedure for the removal of the existing connection and reinstallation of the new connection is included in the disposition of the NCR #59/2731.

5. For all new connections, the affected design drawings have been revised by ECA 01/3793A to change the 1" thick filler plate from ASTM A36 to ASTM A516-Grade 70 steel. The detailed procedures for shop and field welding for the affected connections have been included in the ECA.

6. The detailed welding procedure, material and installation changes for these connections were reviewed and concurred with by Dr. R. S. Stout of

'Lehigh University, Bethlehem, Pennsylvania.

7. Two mock-ups using the ASTM A516 Cr 70 material were welded per the revised procedure. The mock-ups were cross sectioned, ground and etched for macroscopic examination. -No evidence of lamellar tearing or other cracks was~ observed.

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,, ., ,o-D:itcd Stotzs Nuciscr Regulatory Cosmicsien October 12, 1982

- Attention: Mr. Richard W. Starostecki Page 3 The revised welding and installation procedure and material changes for

- these connections will eliminate the problem of lamellar tearing in the 1" thick filler plate. Since the previously installed connections'have been isolated and are being removed and replaced with new con.nections, a sound installation is fully assured.

I Very truly yours, YANKEE ATOMIC ELECTRIC COMPANY I

M J. DeVincentis Project Manager ALL/fsf

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