ML20063F381

Forwards Response to NRC 820723 Request for Addl Info Re Soil Amplification of Seismic Vibration.Response Contains Verification of Figures 33,34 & 35 of Site-Specific Response Spectra. SER Outstanding Issue 3 Resolved

ML20063F381
Person / Time
Site:	Clinton
Issue date:	08/26/1982
From:	Wuller G ILLINOIS POWER CO.
To:	Bernard H Office of Nuclear Reactor Regulation
References
U-0533, U-533, NUDOCS 8208310226
Download: ML20063F381 (8)

Text

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U-0533

/LLINDIS POWER DOMPANY gng_ggggg_ggy5

)f37 500 SOUTH 27TH STREET, DECATUR, ILLINOIS 62525 August 26, 1982 Mr. Harold Bernard, Acting Chief Standardization & Special Proj ects Branch Division of Licensing Office of Nuclear Reactor Regulation U. S. Nuclear Regulatory Commission Washington, DC 20555

Reference:

(1) NRC letter July 15, 1982 on Site Specific Response Spectra, H. Bernard, NRC to G. E. Wuller, IPC (2) IP letter July 23, 1982, U-0522 G. E.

Wuller to H. Bernard, NRC

Dear Mr. Bernard:

Clinton Power Station Unit 1 Docket No. 50-461 In reply to a verbal request made by the NRC on July 23, 1982 by Mr. Leon Reiter and Mr. Gus Giese-Koch concerning soil amplification of seismic vibration at the CPS site, Illinois Power Company wishes to submit the following attached response.

This response contains a verification of Figures 33, 34 and 35 of the CPS " Site Specific Response Spectra" representing the

" Upper", " Middle", and " Lower" bound Soil Properties by the use of a " SHAKE" program as requested.

It is expected that this response will be accepted by the Staff ahd will resolve SER outstanding issue #3 regarding CPS Site Specific Response Spectra.

Sincerely, EAA G. E. Wuller Supervisor - Licensing Nuclear Station Engineering HBP /ja Attach.

cc: Mr. J. H. Williams , NRC Clinton Proj ect Manager (w/att.)

op p/

Mr. H. H. Livermore, NRC Resident Inspector (w/o att.)

Mr. Leou Reiter, NRC (w/att.)

Illinoi s Dept of Nuclear Safety (w/att. )

Mr. Gus Giese-Koch, NRC (w/att.)

8200310226 B20B26 PDR ADOCK 05000461 E PDR

+

., 1 RESPONSE TO NRC REQ 1EST FOR j ADDITIONAL INFORMATION ON SOIL AMPLIFICATION  !

In a telecon on July 23, 1982 Messrs. Giese-Koch.and Reiter of i the NRC staff requested IPC that the amplific,ation curves shown in Figures 33, 34, and 35 of the Clinton site-specific spectra report" (Ref.1) be verified through an independent program (Ref .

2) analysis. -

1 .

To verify the amplification vs. -f requency curves f ar the Clinton site given by Figures 33 through 35 in the Clinton sitt specific spectra report, soil column amplification studies using the SHAKE ~ - -

program were performed for the-upper bound, mean and lower bound

. soil properties. The layer thickness, shear modulus, Poisson's ratio, unit weight and damping values used for the three analyses are shown in Table 1. These soil parameters ar'e identical to Ah#

those used in the soil-structure, analysis using the soil spring method (see Table 220.15-1 of Ref'erence 3).

The input motion was specified at the rock (half-space) outcropping.

The soil amplification f unctions were computed as the-ratio o.L the fourier transform of the resulting surface (top of soil layer

1) motion and the rock outcropping input motion. .The ratios

,'were computed for a f requency range of 0 to 20 Hz at an -increment of 0.09766 Hz. Thus, j t

A(f) =Sff) -

I (1) where A(f) = soil amplification funciton S (f) = Fourier transform of the resulting surf ace motion H(f) = Fourier transform of the input motion at' rock' f outcropping

/ 1 1

Even' though any time history could be used. as the input time history to the rock outcropping for the- purposes of computing amplification function using equation 1, more accurate results are obtained when the input time history is rich in all frequencies-within the frequency range of interest. For this reason a _ N cur.d limited " white noise" with a unif orm f requency content in the 0-50 Hz range was used as the rock outcropping input. The band limited white' noise in the O to f g frequency range is defined by (a) In the tine domain sin (2n of t) h (t) = 2Af o 2n f t o . _.

(b) In the frequency domain H(f) =A lfl < f o

= A/2 lfl = f g

~

=O lfl > ff where A is the desired amplitude and f g is the upper frequency cut-off. -

The comparison of the SHAKE results to those presented in the Clinton site specific spectra report are'shown in Figures 1,

~

2, and 3 for the upper bound, mean and lower bound . soil properties. ,

.It can be observed that the l' HAKE results are in good agreement rwith those presented in the Clinton site specific spectra report; variation in the amplification f actors are attributed to the dif f erences in f requencies at which responses were computed (SHAKE analysis used a very fine frequency interval of 0.09766 Hz) and in the discretization of the soil column (SHAKE ases a continuum - -

formulation as opposed to a finite layer formulation).

2* -

e References -

1. " Site Specific Response Spectra Clinton Power Station - Unit 1 of Illinois Power Company," Revision 1, May 1982, prepared for Sargent & Lundy by Weston Geophysical Corporation.

2. SHAKE, Soil Layer Properties and Response *for Earthquake Motions (09.7.119-3.3). S&L modified program written by J. Lysmer and P. B. Schnabel of the University of California, Berkeley which computes response in a horizontally layered semi-infinite system subjected to vertically traveling shear waves based on the continuous solution of the shear wave equation. ,

3. Illinois Power Company letter no. U-0374 from J. Geier to J. R. Miller; Nuclear Regulatory Commission dated December 3, 1981.

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Table 1 Dynamic soil Properties Used for the Soil Amplificaton Study

• Soil Layer Weight SOIL SHEAR MODULUS (KSF) -

Layer Depth Poisson's Damping

. Number (f t) Density)

(k/ft Ratio Ratio Upper Bound Mean Lower Bound , ,

1 20. 0.132 0.40 0.084 6063. 4547. 3032.

2 105. 0.150 0.35 0.101 7000. 5250.

3500.

3 10. 0.134 0.35 0.059 5500. 4125. 2750.

4 75. 0.145 0.40 0.089 5500. 4125. 2750.

i Hal 5

ae 0.159 0.29 0.000 300000. 300000. 300000.

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' F140 R E 3i SOIL R4PLIFICATION USIt1G " LOWER BOUP10" SOIL PROPERTIES

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