ML20024A644

Forwards Addl Info Re Seismic Design Basis for River Screenhouse.Review of Info Should Help Close Confirmatory Issue 1 of Ser.Values Presented in FSAR Are Reasonable for Matls Underlying River Screenhouse

ML20024A644
Person / Time
Site:	Byron
Issue date:	06/15/1983
From:	Tramm T COMMONWEALTH EDISON CO.
To:	Harold Denton Office of Nuclear Reactor Regulation
References
6706N, NUDOCS 8306220001
Download: ML20024A644 (15)

Text

'

]C Commonwealth Edison

) one First National Plaza Chic'go, Hlinois O ] Address Reply to: Post Office Box 767

(

/ Chicago, Illinois 60690 June 15, 1983 Mr. Harold R. Denton, Director Office of Nuclear Reactor Regulation U.S. Nuclear Regulatory Commission Washington, DC 20555

Subject:

Byron Generating Station Units 1 and 2 River Screenhouse Seismic Design NRC Docket Nos. 50-454 and 50-455 References (a): September 2, 1982, letter from T. R.

Trama to H. R. Denton.

(b): February 7, 1983, letter from B. J.

Youngblood to L. O. DelGeorge.

Dear Mr. Denton:

This is to provide additional information regarding the seismic design basis for the river screenhouse at Byron Generating Station. NRC review of this information should help close Confirmatory Issue 1 of the Byron SER.

Reference (a) provided the justification for use of a 0.2 g Regulatory Guide 1.60 input for the design of the Byron river screen-house. Reference (b) transmitted two FSAR questions requesting additional information tsjarding the seismic design basis for this structure. Question 241.8 requested additional information on soil properties below the river screenhouse.

Test data supporting the dynamic soil properties used in the seismic analyses were discussed with the NRC in a telephone conference on March 14, 1983. It was noted that the structure is founded on natural soil (as opposed to recompacted soil) and that the intact samples are representative of site conditions. Documentation of this information is provided in FSAR Figure 2.5-60, borings G23, RS2, and R53. This letter provides further documentation of our evaluation of the soil data. A summary of this evaluation will be provided in response to Q241.8 in a forthcoming FSAR amendment. -

Enclosed is a letter dated April 8, 1983 from Dames & Moore which presents a reevaluation of the dynamic testing performed on intact and reconstituted soils obtained at the site of the river screenhouse.

For comparison purposes, shear moduli have been calculated from published geophysical data obtained from various sites across the United States.

These moduli have been compared with those obtained at the Byron Station and with those predicted from empirical relationships. In addit, ion, in-situ shear wave velocity versus depth-of the river screenhouse have been calculated and compared to corresponding range of normalized shear modulus factors. This re-evaluation shows that the intact samples are representative for the soil underlying the river screenhouse.

8306220001 80615 lfENU I PDR ADOCK 05000454 E PDR /(/( -

H.'R1.Denton. June 15, 1983 Agreement on proper characterization of the soil dynamic properties is essential design confirmatory issue. to resolution of the river screenhouse seismic soon as the NRC indicates-concurrence with the soil characterizatio Please address further question regarding this matter to this Very truly yours,

}/ N*~

T.~R. Tramm Nuclear. Licensing. Administrator 1m Attachment i

l 6706N I

I j Dames O Moore _

1550 Northwest Highway Park Ridge, Illinois 60068 7g

=b (312) 297-6120 TWX: 910-253-4097 Cable aadress: DAMEMORE April 8, 1983 Sargent & Lundy, Engineers '

55 East Monroe Street Chicago, Illinois 60603 Attention: Mr. R. J. Netzel DM0-35 Gentlemen:

Re: Dynamic Properties, River Screenhouse Byron Station - Units 1 and 2 Commonwealth Edison Company INTRODUCTION This letter presents our reevaluation of the dynanic testing performed on intact and recompacted soils obtained at the site of the River Screenhouse at Byron Station, Units 1 and 2, in Ogle County, Illinois.

We have also calculated shear moduli from publishgd geophysical data obtained at different sites throughout the United States.LII These moduli have been compared with those obtained at the site and with those predicted from empirical relationships.(2,3,4) In addition, we have calculated in-situ shear wave velocities versus depth under the River Screenhouse corresponding to a wide range of normalized shear modulus factors.

EVALUATION OF TEST RESULTS Figure RS-1 shows the results of the cyclic triaxial tests on both intact and recompacted samples plotted in a normalized form. (It should be noted that the foundation for the River Screenhouse was placed on natural soils, and that the River Screenhouse, therefore, is not resting on recompacted material .) The points plotted on this figure were established by anchoring the shear modulus (G), at the lowest strain level obtained during

, the triaxial tests, on the Seed and Idriss(5) normalized shear modulus (G/Gmax) strain degradation curve. By obtaining the normalized shear modulus value at this strain level, a Gmax value for the tests was obtained based on the mean Seed and Idriss(5) strain degradation curve for strains smaller than the minimmn shear strain for the tests. The other data points were then

normalized based on the obtained Gmax value.

The results show that the undisturbed samples exhibit strain degradation characteristics within the range postulated by Seed and Idriss(5).

however, the recompacted soil samples follow strain degradation curves unreasonably steep compared to the normalized curve. We believe these

.j *

Damea & Moore Sargent & Lundy, Engineers April 8, 1983 Page characteristics are the result of the test procedures rather than actual soil properties. The tests on the recompacted samples, completed approximately 1 year prior to the tests on the intact samples, were performed on a machine that had not been calibrated for piston friction. A correction for piston friction is usually not necessary for property tests at high strain values, where high loads are required to obtain the desired deformation. At small strains, where smaller loads are required, the piston friction represents a significant portion of the recorded load. The calculated moduli at lower strains are, therefore, believed to be larger than the true values, which results in an apparent very steep strain degrad& tion relationship from these incorrectly high shear moduli fW low strains. In conclusion, it is our l opir. ion that the curves for the reconstituted sanples are probably in error at i low strains ano are not representative of tile granular material underlying the River Screenhouse. This opinion is further supported by mcre recent test results(6) , which show that the strain degradation curves for granular material may be flatter than those suggested by Seed and Idriss.

SHEAR MODULUS FACTORS FROM EMPIRICAL RELATIONSHIPS The test data on undisturbed sampl es are presented in the form of normalized shear modulus factor K2 versus shear strain on Figure RS-2.

The resonant column data were recorded at a shear strain on the order of 10-4 percent and, thus, represent anchor points. The data indicate normalized shear modulus factors in the range of 40 to 85.

The shear modulus factors for the deposits underlying the River Screenhouse were also evaluated using the empirical expression given by Hardin and Ornevich(2). The average 52 max obtained using this procedure was 68 (Figure RS-3). However, Hardin(3) has proposed that the shear modulus

for granular material is also a function of grain size, in particular the

! particle size at which 5 percent of the sample is finer (D S). Using the procedure proposed by Hardin and a D5 of 0.2 mm (see FSAR Figure 2.5-49), a shear modulus factor of 75 was obtained. Thus, the K 2max values obtained using the empirical relationships proposed by Hardin and Drnevich, and Hardin (68 to 75) fall within the range (65 to 90) given on FSAR Figure 2.5-89.

In addition to using the empirical relationship proposed by Hardin and Drnevich, the shear modulus factor for the deposits underlying the River Screenh(oyse were evaluated using the procedures proposed by Ohsaki and Iwasaki 41 This procedure is based on an empirical rel ationship between dynamic shear modulus as determined from field measurenents and standard split spoon resistance (SPT). Thus, using the SPT values at the River Screenhouse, shear modulus factors in the range of 57 to 122 were obtained, with a mean

. Damea & Moore Sargent & Lundy, Engineers April 8, 1983 Page shear modulus factor of It should be noted, however, that evaluation of field datap5)(Figure 7 RS-3).

indicates that the procedure proposed by Ohsaki and Iwasaki generally overestimates the field shear modulus by approximately 25 percent.

DATA FR0ft FIELD GEOPHYSICAL MEASUREMENT The shear modulus factors obtained for the naterials underlying the River Screenhouse were also compared with those calculated from field data obtainea at other sites (l). The results, shown in Table RS-1 and on Figure RS-4, show shear modulus factors in the range of approximately 40 to 100 for sites with penetration resistance similar to those encountered under the River Screenhouse.

The shear wave velocities presented at other sites (l) were also plotted versus mean standard penetration resistance. The results are shown on Figure RS-5, together with the shear wave velocity calculated using the shear moduli obtained from the procedures of Ohsaki and Iwasaki. The data plotted on Figure RS-5 show that the procedures proposed by Ohsaki and Iwasaki are in good agreement, althgugh close to an upper bound, with field data presented by Shannon and Wilsonll1 Figure RS-6 shows calcul ated shear wave velocities versus depth based on a wide range of normalized shear moduli. Also shown are the shear wave velocities relationships corresponding proposed to the by Hardin shear and moduJi obtained(using Drnevichl2) the Hardin 3) , and empirical Ohsaki and Iwasaki(4). Based on the empirical relationships, the shear wave velocity at the site of the River Screenhouse may vary between approximately 750 and 1600 feet per second. These velocities are in good agreement with the field data presented by Shannon and Wilson (l) (Figure RS-5), which show shear wave velocities in the same range for sites with similar standard split spoon penetration resistances to those encountered under the River Screenhouse at l Byron.

CONCLUSIONS In view of the results obtained of calculations based on empirical relationships (2,3,4) it is our opinion that the values presented on FSAR Figure 2.5-89 (K2 in the range of 65 to 90) are reasonable for the materials underlying the River Screenhouse.

1

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. Dames & Moore K@

Sargent & Lundy, Engineers April 8, 1983 Page If you have any questions regarding this letter, pl ease do not hesitate to contact us.

Very truly yours, DAMES & !100RE ff{bf - W flichael L. Kiefer Partner g

Terje Preber Senior Engineer MLK/TP:lhk Attachments: References Table RS Geophysical and Normalized Shear Modulus Factors for Granular Material Figure RS Normalized Shear Modulus versus Shear Strain Figure RS Shear Modulus Factor K2 versus Shear Strain Figure RS Shear Modulus Factor K2 versus Depth Figure RS Shear Modulus Factor K2 versus SPT Blow Count Figure RS Shear Wave Velocity versus SPT B1 ou Count, Granular Material Figure RS Calculated Shear Wave Velocities versus Depth cc: Mr. L. L. Holish

. Dames & Moore 8

REFERENCES

1. Shannon and Wilson, Inc. and Agbabian Associates,1980, Geotechnical data from accelerograph stations investigated during the period 1975-1979:  :

Summary Report, prepared for U.S. Nuclear Regulatory Commission, NUREG/CR-1643 (September).

2. Hardin, B.O., and Drnevich, V.P., 1972, Shear modulus and damping in soils: measurement and parameter effects: Journal of the Soil Mechanics and Foundation Division, ASCE, vol . 98, no. SM6 (June).

3. Hardin, B.0., 1973, Shear modulus of gravels: University of Kentucky Publ. no. TR74-73-CE19 (September).

4. Ohsaki, Y., and Iwasaki, R.,1973, On dynamic shear moduli and Poisson's ratios of soil deposits: Soils and Foundations, vol . 13, no. 4 (December).

5. Seed, H.B., and Idriss, I.M.,1970, Soil moduli and damping factors for

/!vx?ty! ai&0cv"vk University of Cal i fornia , Earthquake Engineering Research Center, Berkeley, Report no. EERC70-10 (December). /.

6. Arango, I. , Moriwaki , Y. , and Brown, F. , 1978, In-situ and laboratory shear velocity and modulus: Proceedings of the ASCE Geotechnical Engineering Division Specialty Conference on Earthquake Engineering and Soil Dynamics, Pasadena, California (June).

7. Anderson, D.G., Espana, C., and McLamore, V.R.,1978, Estimating in-situ shear moduli at competent sites: Proceedings of the ASCE Geotechnical Engineering Division Specialty Conference on Earthquake Engineering and Soil Dynamics, Pasadena, California (June).

8. Gibbs, H.J., and Holtz, W.G.,1957, Research on determining the density of sand by spoon penetration test: Proceedings, Fourth International Conference on Soil Mechanics and Foundation Engineering, vol. I, pp.

35-39.

9. Mayne, P.W., and Kul hawy, F.H., 1982, K o-0CR relationships in soil :

Journal of the ASCE Geotechnical Engineering Division, vol .108, no. GT6 (June).

10. Marcuson, W.F., and Bieganousky, W.A., 1976, Laboratory standard penetration tests on fine sands: ASCE Annual Convention and Exposition, Liquefaction Problems in Geotechnical Engineering, Philadelphia, Pennsylvania (September).

E.

' TABLE RS-1 1 of 2 GEOPHYSICAL PROPERTIES AND NORMALIZED SHEAR MODULUS FACTOR FOR GRANULAR MATERIAL MEAN SHEAR WAVE DEPTH TO BLOW COUNT DEPTH 'lEL0 CITY WATER TABLE SITE- S0Il CONDITIONS SPT (ft) (ft/sec) (ft) Ko* K2 Cholane-Shandon Array SM 81 135 900 26 1.0. 31 California Alluvium 56 165 1,100 1.0 43 (In-situ Impulse / (Holocene)

Downhole,1975)

Terninal Substation SM 88 95 850 33 1.0 31 El Centro, California Lake Deposit (Downhole,1975) (Quaternary)

Highway Test Lab SP-SM 29 25 750 12 0.6 53 Olympia, Washington Glaciolacustrine (Crosshole,1974) Deposit Cit Millikan Library SM 126 40 1,550 238 1.0 132 Pasadena, California Alluvium '180 80 1,550 1.0 93 (Downhole,1975) (Pleistocene) 155/5" 120 1,950 1.0 121 4800 Oak Grove SW-GW 42 20 1,100 225 0.8 103 Pasadena, California SM-SW 103 40 1,600 1.0 143 (Downhole, 1978) SM-SW (very dense) 80 1,600 1.0 101 SM-SW-GW (very dense) 140 2,000 1.0 120 Alluvium (Pleistocene)

State Building SP 36 25 1,000 20 0.6 87 San Francisco, California (Quaternary 49 55 1,100 1.0 70 (Downhole,1978) Sediments) 122 80 1,600 1.0 127

.

• Estimated based on Gibbs and Holtz,1957 (Ref. 8); Marcuson and Bieganousky,1976 (Ref.10); and Mayne and Kulhawy,1982 (Ref. 9).

TABLE RS-1 (continued) 2 of 2 GEOPHYSICAL PROPERTIES AND NORMALIZED SHEAR MODULUS FACTOR FOR GRANULAR MATERIAL MEAN SHEAR WAVE DEPTH TO BLOW COUNT DEPTH VELOCITY WATER TABLE SITE S0Il CONDITIONS SPT (ft) (ft/sec) (ft) Ko* K2 Lincoln School . Tunnel 91 71 25 1,200 >200 1.0 96 Taft, California Alluvium 121 50 1,200 1.0 69 (Downhole,1976) (Quaternary) 103 80 1,600 1.0 97 Noranda Aluminum Plant SP/SP-SM 23 25 850 11 0.4 77 New Madrid, Missouri Alluvium 32 75 900 0.9 45 (Downhole,1979) (Quaternary) 69 120 1,000 1.0 43 MSU Roberts Hall GW 35 14 750 8 1.0 60 Bozeman, Montana Alluvium 85/6" 25 1,300 1.0 146 (In-situ Impulse,1976) (Quaternary)

PSU Cramer Hall GW 106/6" 105 1,800 133 1.0 112 Portland, Oregon (Downhole,1978)

USU Old Main Building SW-GW 23 15 900 150 0.6 86 Logan, Utah All uvium -

50 1,300 0.5 103 (Downhole,1976) (Quaternary) 66 90 1,600 1.0 96 1900 Avenue of the Stars SP/SM 102/6" 80 1,300 64 1.0 70 Los Angeles, California Pleistocene 124 120 1,800 1.0 119 (Downhole,1975) (Some Cementation)

Hollywood Storage Bldg. SM w/ Gravel 61 120 1,400 40 1.0 77 Los Angeles, California Alluvium (Downhole,1979) (Quaternary)

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