ML20055A120

Forwards Revised Page 9 Re Underpinning to 820708 Draft Supplemental SER

ML20055A120
Person / Time
Site:	Midland
Issue date:	07/09/1982
From:	Poulos S GEI CONSULTANTS, INC. (FORMERLY GEOTECHNICAL ENGINEER
To:	Kane J Office of Nuclear Reactor Regulation
References
81907-14, NUDOCS 8207150495
Download: ML20055A120 (2)

Text

9 $U " b l.50-33d GEOTECHNICAL ENGINEERS INC.

y 1017 M AIN STREET WINCHESTER M ASSACHUSETTS 01890 f617) 729-1625 e u .. n I'VT t 4 L e$

"n*% ?':Mif cw *'o " s t *o July 9, 1982 Project 81907 File 2.0 Ref: 81907-14 Mr. Joseph Kane Project Officer U. S. Nuclear Regulatory Commission Division of Engineering, M/S P-214 Washington, D.C. 20555

Subject:

D ra f t Supplemental Safety Evaluation Review, Page 9 Midland Plants 1 and 2 Selected Sections Regarding Underpinning

Dear Mr. Kane:

Please insert the enclosed page 9 for the page 9 sent with the subject report dated July 8, 1982.

Sincerely yours, GEOTECHNICAL ENGINEERS INC.

% /

/ M r%

Steve J. Poulos Principal SJP:ms Encl.

cc: Mr. Reuben Samuels Mr. Hari Singh 8207150495 820709 PDR ADOCK 05000329 E PDR

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E i

2.5.4.5.4 Lateral Loads The underpinning system is designed to resist lateral earth pressures that will exist temporarily during construction and permanently during the operating life of the plant.

The permanent system has been designed to support both static and seismic earth pressures, the associated water pressures, and i the surcharge effects of adjacent structures (e.g., see CPC, Dec.

3, 1981). The static lateral pressures were obtained from FSAR Table 2.5-15 and the seismic lateral pressures were taken from

FSAR Table 2.5-45.

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[ The factors of safety of the originally designed structures 1

against sliding and overturning are shown in FSAR Subsection 3.8.6.3. The factors of safety for the underpinned structures are expected to be equal to or greater than those computed for the. original structures. (Note: On page 4, Section 4.0 of CPC, Dec. 3, 1981 the Applicant has a *ypographical error. It is stated in error that the factors of safety would be reduced due to the underpinning.)

i 1 During underpinning only the static lateral earth and water pressures were used for design. In addition, at certain stages during underpinning of the CT, EPA's and FIVP's there will be earth pressures on one side of the underpinning wall that are not balanced on the opposite side. The materials beneath these structures are being removed and replaced with properly compacted fill or concrete. These temporarily unbalanced earth pressures j are being supported by sheeting and bracing, as necessary, to provide adequate safety during construction.

The Staff considers the design methods used to be acceptable, with the exception that the computations of lateral sliding resistance of the SWPS currently are being reviewed and will be discussed during an Audit.

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