ML19331C248
| ML19331C248 | |
| Person / Time | |
|---|---|
| Site: | Vallecitos File:GEH Hitachi icon.png |
| Issue date: | 08/13/1980 |
| From: | Darmitzel R GENERAL ELECTRIC CO. |
| To: | Eisenhut D Office of Nuclear Reactor Regulation |
| References | |
| NUDOCS 8008140451 | |
| Download: ML19331C248 (6) | |
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G E N E R A L h, E LE CTR I C ENGINEERING GENERAL ELECTRIC COMPANY, P.O. BOX 460. PLEASANTON, CALIFORNIA 94566 DIVISION
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August 13, 1980
=l h) t Mr. Darrell G. Eisenhut, Director Division of Project Management
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Office of Nuclear Reactor Regulation U.S. Nuclear Regulatory Commission Washington, D.C. 20555
SUBJECT:
Soil Shear Modulus and Bearing Capacity Values For The Soil Beneath The General Electric Test Reactor (GETR) -
License TR Docket 50-70
Dear Mr. Eisenhut:
The General Electric Company's response to questions raised regarding soil shear modulus and bearing capacity values at our meeting of July 30,1980 with the NRC Staff is attached. The responses support our position that the values selected are appropriate and are consistent with those used in the structural evaluations.
Very truly yours, hkW R. W. Darmitzel, Manager Irradiation Processing Operation
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AFFIRMATION
- g The General Electric Company hereby submits the information pertaining
.to soil shear modulus and bearing capacity of the ' oil beneath the GETR.
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.To the best of my knowledge and belief, the information contained herein is accurate.
--u OFFICIAL SEAL VLT# Ed@P$ECOtNCEfA R. W. Darmitzel, Manager Irradiation Processing Operation-ALM. EDA CCumY f3y comm. cr; ires f. TAR 9, !!S1 L
Submitted and sworn before me this 13th day of August,1980, 44f6fa.g Notary Public in and for the
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[30 CAL 50U5IA AVE., SUliE 301, PALO ALTO. CALIF. 94306
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PHONE 415 / 326-0383
. August 8, 1980 Mr. Dwight Gilliland Manager of Reactor Irradiation General Electric Company (GETR) (VNC 104)
Vallecitas. Nuclear Center Vallecitos Road Pleasanton, California 94566
Subject:
Engineering Support Services - GETR Soil Properties EDAC Project 117-258
Reference:
ESA Letter (Meehan) to EDAC (Kost) dated 8 August 1980
Dear Dwight:
We have reviewed the referenced memo.regarding shear modulus and bearing capacity of the soil materials beneath the GETR Reactor Building f oundation. Our coments are as follows:
Soil Shear Modulus The structural analyses for the load case of vibratory ground motions were performed for a soil shear modulus of G = 1,000 ksf, which is nearly equal to the upper value of G = 1,100 ksf in the referenced memo.
Analyses show that use of G = 1,100 ksf would increase the shears and moments in the Reactor Building concrete core structure by only 4 percent. There is an adequate safety margin to accommodate this insignificant increase.
Analyses also show that use of a lower value of G = 500 ksf mentioned in l
the referenced memo would decrease shears and moments by about 30 percent. This would greatly increase the already adequate margin of safety.
j Bearing Capacity The structural analyses for the combined load case of vibratory motions and surface rupture offset were performed for the case where the ultimate bearing capacity of the soil beneath the Reactor Building is 20 ksf.
Use of this value, which is at the upper end of the range given in the referenced memo, results in more severe load cases for the structure than i
if lower values'were to be used.
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-August 8,.1980-Page 2 Conclusions
- Tne snear modulus and bearing capacity given-in the re'ferenced memo are consistent with those used-in the structural evaluations. Thus, the.
conclusions recarding the~ seismic adequacy of the GETR Reactor Building do not change.
Very truly yours, l
aarrison Kost' Vice President for ENGINEERING DECISION ANALYSIS' COMPANY, INC.
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701 Welch Road, Pato Alto, Califomia 94304 Ei5c'sTr"Ah!ItS' (415) 321 3071
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August 8,1980 uoucm a muou 1883 Mr. Gary Kost
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'/NjN ]VmQNIA C. cAnemo@]ff EDAC-480 California Ave., Suite 301 Palo Alto, California 9430G i g q tmW PUSUC - CAUFOkN y Qf nAmoA ccum FO ccmm. c7pires MAR 3. I 31 Re: Subgrade Soil Values, GETR
Dear Gary:
d Following various discussions we have had on this matter, I am forwarding comments regarding soil modulus and bearing values which we have previously recommended for use in your scismic analyses of GETR.
Subgrado Shear Mo< hilus und Shear Wave Velocity - It is important to note that the values of these purameters are appropriate for the very strong carthquake shgking which is being assumed in analysis. IIcnce, our recommended value of 1.1 x 10 psf for the upper soil unit may appear low in comparison to values used for moderate carthquakes or field geophysical tests.
0 The value' G = 1.1 x 10 psf cheeks with a value of K = 18 from Figure 5 of
" Soil Moduli and Damping Factors for Dynamic Response Analysis" Report EERC 70-10, College of Engineering, University of California, a standard method for determining modulus.
g The indicated shear wave velocity of 500 fps was derived from the G = 1.1 x 10 psf shcar modulus.
The justification for use of a minimum 0.1 percent strain is as follows; free field soil strains of 0.2 percent would be expected during earth-quckes with surface particle velocitics of 1 ft/sec.
additional strains would be superimposed on the subgrade by soil-structure interaction. These strains would be roughly equal to the dynamic angular rotation of the reactor foundation. For a strain of 0.1' percent, rotation observed at the edge of the foundation would be less than 0.5 inch.
In a strong carthquake, it is likely that subgrade strains will be gester than 0.1 percent, with corresponiling moduli values on the order of 0.5 x 10 psf. This value correlates well with the Inboratory modulus determined by Shannon and
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Wilson, of E = 500 gf, from which I derive G = 0.4 x 10 psf.
Hence, the recommended 1.1 x 10 psf should be an upper limit, i.e. conservatively on the high side.
11 caring Capneity - Our estimate of the probable realistie range of bearing capacity for rapid loading conditions is 15 to 20 ksf. This is intended as a realistic range, i.e., it does not incorporate any reduction factors as it would if it were being used as an allowable bearing value. The bearing value is to be used to determine the area of soil that would support the reactor under the worst combination of faulting and ground shaking; therefore it should be a realistic value, if the rest of the analysis is to be corrcspondingly realistic. In fact, there are ome "conservatisms" in this recommended range. Local bearing failure should occur below this range, and eccentric loading components should also cause subgrade deformation at less than 15-20 ksf.
Very truly yours, "V Y b, b Richard L. Meehan RLM/am A
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