ML20153E388

Forwards Request for Addl Info to Suppl Util 871026 Info on Differential Settlement of Buried Pipes,For Response within 60 Days

ML20153E388
Person / Time
Site:	Beaver Valley
Issue date:	05/03/1988
From:	Tam P Office of Nuclear Reactor Regulation
To:	Sieber J DUQUESNE LIGHT CO.
References
TAC-62885, NUDOCS 8805090472
Download: ML20153E388 (3)

Text

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, May 3,1988 l

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Docket No. 50-412 Mr. J. D. Sieber, Vice President  ;

Duquesne Light Company Nuclear Group

Post Office Box 4 Shippingport, PA 15077

SUBJECT:

BEAVER VALLEY UNIT 2 - DIFFERENTIAL SETTLEMENT OF BURIED PIPES (TAC 62885)

, f Your letter dated October 26, 1987 provided a response to our Request for ,

Additional Information (RAI) dated June 2,1987. However, that response was ,

not corplete. The enclosed RAI describes our information need to con;plete this action.

)

Please respond within 60 days of receipt of this letter.  ;

The reporting and/or recordkeeping requirements contair.ed in this letter . I affect fewer than ten respon-dents; therefore, CMB clearance is not required under P.L.96-511.

Sincerely, l original signed by ,

i Peter S. Tam, Project Manager $

3 Project Directorate I-4 j Division of Reactor Projects I/II

Enclosure:

As stated i

cc w/ enclosure: See r. ext page l r

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Fr. J. Sieber Duquesne Light Conipany Beaver Valley Power Station Units 1 8 2 cc:

Bureau of Radiation Protection Jay E. Silberg, Esquire Pennsylvania Departrent of Environrental Shaw, Pittman, Potts and Trowbridge Resources ,

7300 N Street, N.V. ATTN: R. Jarati Washington, DC 70037 Post Office Box 7063 1 Harrisburg, Pennsylvania 17170 1 Kenny Grada, Manager Payor of the Borrough of Nuclear Safety Shippingport Duquesne Light company Post Office Box 3 '

P. O. Roy 4 Shippingport, Pennsylvania 15077 Shippingport, Pennsylvania 15077 Villiam Lacey, Maniser Ashley C. Schannsuer Nuclear Cperations Department Assistant City Solicitor Post Office Box 4 City of Pittsburgh Duquesne Light Company 313 City-County Building ' '

Shippingport, Pennsylvania 15077 Pittsburgh, Pennsylvania 15219 John A. Lee Esquire Regional Administrator, Region i Duquesne Light Company U.S. Nuclear Regulatory Comission One Oxford Centre 475 Allendale Pcad 301 Grant Street King of Prussia Pennsylvania 19406 '

Pittsburgh, Pennsylvania 15279 P.F. Camichael, Comissioner Resident Inspector Departrent of Labor U.S. Nuclear Regulatory Comission 1800 Vashington Street East Post Office Box 181 Charlesten, West Virginia 25305 Shippingport, Pennsylvania 15077 John D. Borrows Director, Pennsylvania Energency Director, Utilities Department Paragerent Agency Public Utilities Comission Post Office Eox 3321 i

, IE0 East Broad Street Harrisburg, Pennsylvania 17105-3321 l Colur. bus, Ohio 43266-0573 l l

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,- . Enclosure l

. BEAVER VALLEY POWER STATION UNIT NO. 2 REQUEST FOR ADDITIONAL INFORMATION

REFERENCES:

1. Letter dated October 23, 1986 from J. J. Carey, Duquesne Light Co. (DLC), to H.R. Denton, NRC, i

Subject:

Beaver Valley Powr St6 tion Unit 2 Response to SER Confirmatory item 2 ,

i

2. Letter dated March 9,1987 from J.J. Carey, DLC,  !

to NRC,

Subject:

Beaver Valley Power Stetion Unit No. 2 Response to SER Confinnatory Item 2.

2. Letter dated June 2,1987 from P. S. Tam, NRC, to J. J. Carey, DLC,

Subject:

Beaver Valley i' Unit 2 Effects of Differential Settlement against buried pipes.

4. Letter dated October 26, 1987 from J.J. Carey, DLC, i to NRC, Subject cited above The licensee has compared the calculated pipe stresses with the allowable pipe stresses at three different locations. At the first location between the intake structure and the valve pit, the computed differential settlement at the most l critical section of the pipeline is S.7 in. in a pipe length of 30 ft. (Ref. 4).

The maximum calculated pipe stress due to this differential settlement is 49548 psi against the allowable stress of 52,500 psi. While the computed pipe stress at the first location is only about 5 percent less than the allowable stress, the computed pipe stresses at the second and third locations (i.e. near the Safeguards building and Auxiliary building) are approximately 60 percent and i 90 percent less than the allowable stresses respectively. Thus there is very little margin of safety at the first location, while there is ample margin at I the other two lo:ations.

In view of the fact that the computed pipe stress of 49548 psi at the first location is very close to the allowable pipe stress of 52,500 psi, it is necessary to critically examine the pipe design criteria and the actual calculation of both the differential settlement and the pipe stresses, even though the staff has generally approved the analysis procedures outlined in the FSAR.

a) Provide a sumary of the detailed calculations along with a sumary of the soil data to substantiate the differential settlement of 5.7 inches at the most critical section of the Service Water System (SWS) pipes running north from the valve pit to the intake ,

structure shown in Reference 4 j.

1 b) Is the dynamic seismica,11y induced settlement (including the effects of wave travel and wave reflection) considered in determining the  !

maximum differential settlement of buried pipes? If so, provide the l magnitudes of both static and dynamic settlements due to different i loadings separately.  !

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