ML20148S328

Forwards Insp Data & Conclusions for EDG Exhaust Insp Conducted During First Ten Year Insp Interval at Seabrook Station on 960624.Concluded That EDG Exhaust Elbow Is Acceptable for Continued Operation

ML20148S328
Person / Time
Site:	Seabrook
Issue date:	06/27/1997
From:	Feigenbaum T NORTH ATLANTIC ENERGY SERVICE CORP. (NAESCO)
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
NYN-97068, NUDOCS 9707080192
Download: ML20148S328 (7)

Text

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. - * *i North North Atlantic Energy Service Corporation l

P.O. Box 300 Atlantic seahr-t. Nu o3874 0

(603) 474-9521 The Northeast Utilities System i

June 27,1997 I

Docket No. 50-443 NYN-97068 United States Nuclear Regulatory Commission Attention: Document Control Desk Washington, D.C. 20555 l

Seabrook Station Emercency Diesel Generator Exhaust Inspection North Atlantic Energy Service Corporation (North Atlantic) has enclosed the inspection data and i

conclusions for the Emergency Diesel Generator (EDG) Exhaust Inspection conducted during fir.st ten year inspection interval at Seabrook Station. This inspection was conducted on June 24, 1996, followed by Engineering review of the inspection results.

j North Atlantic committed, as documented in the Seabrook Station Safety Evaluation Report (SER)' Section 9.5.8 to an inspection program for the EDG exhaust system piping and to submit the results of the first inspection to the NRC. The inspections are to ensure that unacceptable wall thinning will not occur during the 40-year design lifetime of the system. The inspection program includes one EDG exhaust system and is initially limited to the area of highest potential corrosion and erosion, the exhaust silencer outlet elbow. Enclosed are the results of the first t

O inspection conducted on the "A" EDG. North Atlantic has concluded that the EDG exhaust

>(O T elbow is acceptable for continued operation. North Atlantic will perform a second inspection on ij the EDG by the end of the sixth refueling outage. That outage is scheduled to begin in the first quarter of 1999.

' NUREG-0896," Safety Evaluation Report Related to the Operation of Seabrook Station, Unb 1 and 2," March 1983.

9707090192 970627 I

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IJ.S. N'uclear Regulatory Commission

,, NYN-97068/Page 2 i

r Should you have any questions regarding this response, please contact Mr. Terry L. Harpster, l

Director of Licensing Services, at (603) 773-7765.

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Very truly yours, NORTH NTIC ENERG ' SERVICE CORP.

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/ sfr C. Feig6fibaum

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j Executive Vice PrB ' ent and Chief Nuclear Officer 1

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II. J. Miller, Region I Administrator l

A. W. De Agazio, Sr. Project Manager l

W. T. Olsen, NRC Senior Resident inspector t

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ENCLOSURE TO NYN-97068 l

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ULTRASONIC THICKNESS' EXAMINATION REPORT

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in N4 at the support weld, the reading was.565 which is a difference of 75 mils from the baseline.

i Remainder of inspection (rows 5-21) unable to be performed due to welded support interference.

Original exam performed on the ID of elbow.

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CONCLUSION:

i The "A" Train DG exhaust elbow is acceptable for continued operation. This conclusion is based on the following rationale:

'lhe maximum wall loss at location J2 is 0.093"(0.845" to 0.752"). The existing pipe stress anslysis, which is documented in Calculation MCD 600.10 considers the elbow at 0.375" thick. Maximum stress levels in the elbow based on 0.375" thickness are 713 psi (Deadweight),712 psi (OBE) and 1080 psi (SSE). The allowable stress for the elbow material is 17500 psi. Minimum safety factor for ASME Equation (9) based on the elbow being 0.375" is (1.2* 17500)/(713+712) = 14.7.

To monitor any further wall loss, a second inspection shall be performed by the end of ORO 6 for cvaluation.

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