ML20245C669
| ML20245C669 | |
| Person / Time | |
|---|---|
| Site: | Beaver Valley |
| Issue date: | 10/26/1987 |
| From: | Carey J DUQUESNE LIGHT CO. |
| To: | NRC OFFICE OF ADMINISTRATION & RESOURCES MANAGEMENT (ARM) |
| Shared Package | |
| ML20245C672 | List: |
| References | |
| 2NRC-7-209, NUDOCS 8711030311 | |
| Download: ML20245C669 (6) | |
Text
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'Af Telephone (412) 393-6000
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Stuppingport. PA 15077-0004 October 26, 1987 2NRC-7-209 United States Nuclear Regulatory Commission ATTN:
Document Control Desk Washington, DC 20555
SUBJECT:
Beaver' Valley Power Station - Unit No. 2 Docket No. 50-412, License NPF-73 Differential Settlements of Buried Pipes (NRC Licensing Action TAC 62885)
REFERENCES:
(a)
NRC Letter dated June 2, 1987, Mr. Peter Tam to Mr.
J. J.
Carey l
(b)
DLC Letter 2NRC-7-045, dated March 9, 1987, Mr. J.
J.
Carey to U.
S. Nuclear Regulatory Commission (c)
DLC Letter 2NRC-6-lll, dated October 23, 1986, Mr.
J.
J.
Carey to U.
S. Nuclear Regulatory Commission i
Gentlemen:
In Reference (a),
the NRC requested that Duquesne Light Company (DLC) provide. additional information related to the DLC submittals provided in References (b) and (c) concerning differential settlements of buried pipes at Beaver Valley Power Station - Unit No.
2 (BVPS-2).
The specific information requested in Reference (a) is as follows:
(1)
For the October 1986 submittal, provide the results of the analysis for pipes located between structures.
(2)
For the March 1987 submittal, provide details of the analysis for pipes buried in embankment slopes.
In a
telecon on September 22,
- 1987, between DLC and NRC representatives, DLC obtained clarification as to the information needed by the NRC.
Based on this telecon, the attachments to this letter provide information on (1) the critical differential settlement of the two 30 inch Service Water System (SWS) pipes from the intake structure to the valve pit, (2) differential settlements between the closely spaced main plant area structures that are used for pipe stress
- analysis, and (3) differential settlements along buried; safety-related piping that extends from the plant structures out into the yard area.
0 8711030311 871026 PDR ADOCK 05000412 i
P PDR
, Beaver Valley Power Station'- Unit No. 2 Docket No. 50-412, License NPF-73 Differential Settlements of Buried Pipes (NRC Licensing Action TAC 62885)-
Page 2 Attachment' 1 provides a copy of the settlement profile along the east SWS line (2SWS-030-041-3) running north from the valve pit to the intake structure.
This profile is from the original calculation of settlement along the _SWS pipes and was incorporated as part of j
Figure 2
in Reference (b).
The most critical section of the SWS pipes was found to be between points A and B on the east pipe where the settlement gces from 0 to 5.7 inches over a distance of 30 feet.
The maximum stress in the SWS pipe as a result of this differential settlement was determined to be 49,548 psi which is satisfactory
{
compared to the allowable stress of 52,500 psi.
j Attachment 2
provides a
copy of the SWEC calculation titled
" Differential Settlement of SWS lines between Reactor and Safeguards".
This is an example of the method used to determine differential settlements between closely spaced structures that are used for pipe stress analysis at the piping penetrations.
In this
- method, which is described in Reference (c)
(FSAR Section 2.5.4.10.2),
the observed settlement data was used to determine the differential settlement.
The maximum stress developed in these SWS lines due to differential settlement is 16,654 psi compared to an allowable stress of 45,000 psi.
Attachment 3
provides a
copy of pertinent portions of the SWEC calculation titled
" Settlement of SWS pipes adjacent to Auxiliary Building".
This calculation was prepared using the procedure described in (FSAR Section 2.5.4.10.2).
The constrained moduli were calculated for the initial conditions and the computer program SETTLE II was run.
The stresses caused by fill placement and adjacent structures were determined from the SETTLE II run.
The new stresses were used to determine a final value of constrained moduli (using the Hardin and Black equation).
An average value of constrained moduli for each layer was determined and another SETTLE II run was made to obtain the final initial elastic settlement.
The stresses due to differential settlement along these lines are quite small (3600 psi) compared to the allowable stress (41,100 psi).
t DLC believes that the coove noted attachments provide the information necessary for the NRC to complete their review of differential settlements of buried pipes at BVPS-2.
V ry ruly yours, b
7 k)J Carey Seni Vice President, Nuclear Attachments
r Beaver Valley Power Station - Unit Noe 2 Docket No. 50-412, License NPF-73 Differential Settlements of Buried Pipes (NRC Licensing Action TAC 62885)
Page 3 cc:
(w/o attachments)
Mr. J. Beall, Sr. Resident Inspector (Unit 2)
Mr. W. T. Russell, NRC Region I Administrator Mr.
P.' Tam, Project Manager INPO l
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1 i
ATTACHMENT 1
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1
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OVERSIZE DOCUMENT PAGE PULLED SEE APERTURE CARDS 1
NUMBER OF OVERSIZE PAGES FILMED ON APERTURE CARDS l
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l APERTURE CARD /HARD COPY AVAILABLE FROM DOCUMENT CONTROL BRANCH FTS 492-8989
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l' ATTACEDENT 2 i
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