ML20086K008

Second Interim Deficiency Rept,Item 92 Re Bolted Structural Connections W/Excessive Gaps & ASTM A325 Nuts on ASTM A490 Bolts.Initially Reported on 820702.Procedures Revised to Require Insp for Mating Surface Gaps During Erection

ML20086K008
Person / Time
Site:	Harris
Issue date:	01/20/1984
From:	Parsons R CAROLINA POWER & LIGHT CO.
To:	James O'Reilly NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
References
CON-NRC-172 92, NUDOCS 8401260176
Download: ML20086K008 (4)

Text

n CP&L Carolina Power & Light Company w m . ,------.2 P. O. Box 101, New Hill, N. C. 27562 2) A 8*. 8 8 January 20,1984 Mr. James P. O'Reilly NRC-172 United States Nuclear Regulatory Commission Region II 101 Marietta Street, Northwest (Suite 2S00)

Atlanta, Georgia 30303 CAROLINA POWER & LIGHT COMPANY SHEARON HARRIS NUCLEAR POWER PLANT 1986 - 900,000 KW - UNIT 1 BOLTED STRUCTURAL CONNECTIONS WITH EXCESSIVE GAPS AND ASTM A325 NUTS ON ASTM A490 BOLTS, ITEM 92

Dear Mr. O'Reilly:

Attached is our second interim report on the subject item which was deemed reportable per the provisions of 10CFR50.55(e), on April 26, 1983. CP&L is pursuing this matter, and it is currently projected that corrective action and submission of the final report will t, accomplished by June 1,1984.

Thank you for your consideration in this matter.

Yours very truly, 7/f R. M. Parsons Project General Manager Shearon Harris Nuclear Power Plant RMP/sh Attachment cc: Messrs. G. Maxwell /R. Prevatte (NRC-SHNPP)

Mr. R. C. DeYoung (NRC) 8401260176 840120 00W g DR ADOCK 05000400 'OF M s Ws' R f

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,o CAROLINA POWER & LIGHT COMPANY SHEARON HARRIS NUCLEAR POWER PLANT UNIT NO. I SECOND INTERIM REPORT BOLTED STRUCTURAL CONNECTIONS WITH EXCESSIVE GAPS AND ASTM A325 NUTS ON ASTM A490 BOLTS ITEM 92 January 20,1984 1

REPORTABLE UNDER 10CFR50.55(e)

1 9

SUBJECT:

Shearon liarris Nuclear Power Plant / Unit No. I10CFR50.55(e),

reportable deficiency, Bolted Connections with Excessive Gaps and ASTM A325 Nuts on ASTM A490 Bolts.

ITEM: Bolted structural steel connections in the Unit No.1 Turbine and Con'.ainment Buildings have gaps, or areas with 0% contact between mating surfaces in friction connections. The part of this problem concerning the use of A325 nuts on A490 bolts was previously found to be non-reportable and so reported on November 30,1982 (CP&L letter NRC-26).

SUPPLIED BY: Not a supplier-related deficiency. All structural connectioas concerned were field assembled.

NATURE OF DEFICIENCY: The Turbine Building is seismically designed per Regulatory Guide 1.29, and the Containment Building is a Seismic Class I structure. All structural connections were designed as friction type connections requiring solid seating of the mating surfaces.

These connections were previously inspected and accepted.

DATE PROBLEM OCCURRED: June 22,1982 DATE PROBLEM REPORTED: On July 2,1982, Mr. L. E. Jones notified the NRC (Mr. A.

Hardin) that the item was potentially reportable. On April 26, 1983, Mr. N. J. Chiangi notified the NRC (Mr. A. Hardin) that this item was reportable per the provisions of 10CFR50.55(e).

SCOPE OF PROBLEM: A reinspection of the entire Turbine and Containment Buildings, including all structural connections where there was a potential for these gaps occurring, had been completed. An engineering evaluation had determined that the gaps would not i occur in connections with beam end clips or plates less than -

l 5/8" thick. In standard design, these clips deflect slightly l under bolt tension to make contact with the adjacent mating

! surface. Main support girder end clips were generally fabricated from 1" thick angle, and end plate thicknesses in some members exceeded 2".

I A total of approximately 878 connections were reinspected in the Turbine Building and approximately 500 in the

! Containment, with gaps being found in approximately 154 and i approximately 36, respectively. An additional 59 connections in the Turbine Building with gaps have been identified in inspections since the reinspection addressed by this reportable j item was completed. These connections were found to lack

documentation, indicating they had not been inspected l previously.

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SAFETY IMPLICATION: The inability of the end clips and end plates to deflect under bolt tension, to close the mating surface gaps resulting from fabrication tolerances (allowing the girders to be fabricated slightly short for erection purposes) has two implications. The lack of contact area may affect the slip resistance in the friction connection. But more in.portantly, where the surfaces are not in contact, the bolt tension load is transferred to the weld attaching the clip or plate to the girder, potentially overstressing the weld.

REASON DEFICIENCY IS REPORTABLE: Reportable due to the magnitude of the probleni plus the extensive evaluation and/or rework required.

CORRECTIVE ACTh0N: Appropriate site technical procedures have been revised to specifically require inspection for mating surface gaps during erection. Inspection and craft personnel have received additional training in inspection and erection of structural steel through formal classes and on-the-job training.

Permanent Waivers (PW's) have been written, requiring engineering evaluation, for each deficient connection. Each connection will be accepted "as-is", as not being significantly deficient, or repaired to make it acceptable, based on this engineering evaluation. To date,52% of the connections with gaps in the Turbine Building and 100% of those in the Containment Building have been evaluated for acceptability.

Of these, 7 in the Turbine Building required rework, and 1 of these has been completed.19 connections in the Containment Building required rework and 12 have been completed.

Engineering evaluation of the remaining connections identified as having gaps is continuing, and rework of those connections for which it is required is in progress.

FINAL REPORT: A final report will be issued when the evaluaticn and rework are complete. We now expect to issue a final report by June 1, 1984.

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