ML20009E369

Interim Rept of Significant Const Deficiency 30 Re change- Out of ASTM A193 SS Bolts on Motor Control Ctr Bus Bars. Final Rept Will Be Submitted by 811030

ML20009E369
Person / Time
Site:	Waterford
Issue date:	07/13/1981
From:	Aswell D, Milhiser R, Wills J LOUISIANA POWER & LIGHT CO.
To:	Seyfrit K NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV)
References
10CFR-050.55E, 10CFR-50.55E, W3K81-0256, W3K81-256, NUDOCS 8107280093
Download: ML20009E369 (4)

Text

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3 LOUISIANA 142 ORARONDE SJ

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\ce President-Power Pmducten July 13, 1981 W3K81-0256 Q-3-A35.07.30 Mr. K. V. Seyfrit, Director, Region IV

n yI m e s Ulm U. S. Nuclear Regulatory Commission Office of Inspection and Enforcement 1 g { 6 {9M i( j; k

611 Ryan Plaza Drive, Suite 1000 y _

Arlington, Texas 76012 o L

SUBJECT:

Waterford SES Unit No. 3 Docket No. 50-382 Interim Report of Significant Construction Deficiency No. 30

" Change Out of ASTM A193 S. S. Bolts on Motor Control Center Bus Bars"

Reference:

Telcon - R. Bennett (LP&L QA) to R. C. Stewart (USNRC) on 6/12/81

Dear Mr. Seyfrit:

, In accordance with the requirements of 10CFR50.55(e), we are hereby l providing two copies of the Interim Report of Significant Construction l Deficiency No. 30, " Change Out of ASTM A193 S. S. Bolts on Motor Control l Center Bus Bars."

If you have any questions, please advise.

l Very truly yours, D. L. Aswell l DLA/LLB/grf Attachment cc: 1) Director ~

Office of Inspection & Enforcement j U. S. Nuclear Regulatory Commission 3  ;

Washington, D. C. 20555 (with 15 copies of report)

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2) Director Office of Management Information and Program Control U. S. Nuclear Regulatory Commission Washington, D. C. 20555 8107280093 81071 PDR ADOCK 05000382 S PDR j

r LOUISI ANA P0h'ER & LIGilT COMPANY WATERFORD SES UNIT ::0. 3 Interim Report of Significant Construction Deficiency No. 30 Change Out of ASTM A193 S. S. Bolts on Motor Control Center Bus Bars Reviewed by _

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R. J. 1 er - Site Manager / Date Reviewed by ,' '

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J./ LT Wills - Project Superintendent ~ Date

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J. Ilart -~ Project Lipensing Engineer

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R. A. liartnett - Q. A. Site Supervisor Date July 2, 1981 i

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r INTERIM REPORT SIGNIFICANT CONSTRUCTION DEFICIENCY No. 30 CHANGE OUT OF ASTM A193 S.S. BOLTS ON MOTOR CONTROL CENTER BUS' BARS INTRODUCTION This report.is submitted pursuant to 10CFR50.55(e). It describes a de-ficiency in the selection of fastener material'for the MCC and switch-gear bus connections which resulted in overtorqueing of the fasteners.

This problem is considered reportable under the requirements of 10CFR 50.55(e). To the best of our knowledge, this problem has not been iden-tified_to the Nuclear Regulatory Commission pursuant to 10CFR21.

BACKGROUND The deficiency occurred during corrective action rework associated with Nonconformance' Report K3-2250 issued to document the rusting of the fas-teners on the MCC and switchgear bus connections. The disposition re-quired that the rusty bolts be changed out with ASTM A193 material, but the grade was not specified. During procurement of the replacement bolts, ASTM A193, Class 1:B8 bolts were specified based on corrosion resistance considerations. Structural adequacy requirements were not considered at this time.

The initial installation utilized SAE GR S (or better) steel, torqued to 40 + 5 ft. lbs. in accordance with Drawings 5817-2701 through 2703. This .

type of bolt has a yield strength of 92 KSI (minimum) and a tensile strength of 120 KSI (minimum).

The ASTM A193, Class 1:B8 bolts have a yield strength of 30 KSI (minimum) l- and a tensile strength of 75 KSI.(minimum).

DESCRIPTION OF DEFICIENCY l

During rework installation activities, the torque value to which the fas-I teners were being torqued was questioned. 'At this point in time, ASTM A193

( bolts had been installed in nine (9) of the 32 McC's. Of these, the follow-ing six (6) are safety-related and affect several systems:

3B312 3A312 3B311 3A411 3B313 3B411

, A sample of the ASTM A193 Class bolts were tested and found to break in I

the 50 to 55 ft. lbs. region in general, with one bolt breaking at approxi-

-mately 48 ft. lbs. In turn, installed bolts were removed from completed MCC buses for inspection; and the majority of these bolts exhibited ' neck-ing.' On the basis of this evidence, the bolts were found to be improper for this application.

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r-s ANALYSIS OF SAFETY IMPLICATIONS If this deficiency were left uncorrected, possible degradation of safety systems could occur. Such degradation would occur through the complete failure of the MCC if a short circuit were to take place. If a failure of this type were to occur to an MCC when its redundant division was out of service, the safety analyses presently in the FSAR would be invalidated.

CORRFCTIVE ACTION Nonconformance Report k'3-2750 documents and dispositions this deficiency.

The disposition requires that ASTM A193 Class 1:BS bolts be removed and replaced with bolts of a tensile and yield strength equal to or greater than originally supplied SAE GR 5 bolts.

The bolt type procured in accordance with this disposition is ASTM A193, Class 2:B8, which has a yield s trength of 100 KS1 (minimum) and a tensile strength of 125 KSI (minimum). Corrective action will be accomplished and a Final Report submitted no later than October 30, 1981.

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