ML19319B335

Amend 4 to PSAR

ML19319B335
Person / Time
Site:	Davis Besse
Issue date:	04/29/1970
From:	Sampson G TOLEDO EDISON CO.
To:
References
NUDOCS 8001150828
Download: ML19319B335 (2)

Text

_ - - . _ _ . __ --

d DAVIS-BESSE 8

_5eigufatory gg, Cy, NUCLEAR POWER STATION mme PRELIMINA.RY SAFETY ANALYSIS REPORT

, Amendment Number 4 4

t m THE

, 'j TOLEDO (N( EDISON COMPANY l

8001150 h 8 1278

April 29,1970 APPLICATION FOR LICENSES FOR DAVIS-BESSE NUCLEAR PC'w3 STATION Docket No. 50-3h6 4

Amend =ent No h ,

Enclosed herewith, amending and supplementing the above entitled application, are revised pages as listed on the attached Index Sheet for insertion in the Preliminary Safety Analysis Report, as previously filed.

THE TOLEDO EDISON COMPANY By w / -- 4 n, v-Vice President. Power Sworn to and subscribed before me, this 29th day of April,1970.

c a u-n cl.

Notary Public N W_

GENEVA I. LEAKE fict:ry Publi . Lucas County Ohio

.(- My Commission Expires Sept. 2,1974

-s exceed that of the shocks caused by heavy artillery to which they were accustomed. This is a confirmation that the earth-quake intersity felt at the site has not exceeded MM V during the last ha.'.f century.

h. Conclusion

Historic records indicate that earthquakes have never been felt at the site with an intensity greater than MM V, and that no earthquakes of epicentral intensity greater than MM V have occurred within 50 mi of the site. There is no reason to believe that the seismicity of the site vill change.

As a group, the intensity of the New Madrid (1811-1812),

the Charleston (1886), and the St Lawrence Valley (1925) earth-quakes was MM IX-X (9 5) to MM XII. Study of these earthquakes shows that.the geology . including soil conditions, in their epicentral areas differs from the site geology and that the site seismicity is much smaller than the seismicity in the epicentral areas of these earthquakes.

Study of the Anna earthquakes, which had a maximum intensity of MM VII-VIII (7 5), indicates that they can be attributed to a local structural weakness in the bedrock and that their effects probably are amplified by the thick soil deposits. Because these conditions do not exist at the site, the seismicity of the site is smaller than that of Anna.

1 Based on the study of the historic regional and local earthquakes, we conclude that earthquakes felt at the site with the intensity of a low MM VI should be considered to have a small probability of occurring, and that it is improbable, but possible, tnat earthquakes be felt at the site with the intensity of a medium MM VII.

C. INFLUENCE OF REGIONAL AND LOCAL GEOLOGIC STRUCTURAL FEATURES ON SEISMICITY l

i

1. Discussion The regional and local geologic structural features which have or may have some effect on the seismicity are dis-cussed below.

2C-27

I 1

l 3

The Ohio-Indiana Plat form is south of the site, where the Cincinnati Arch bifurcates into the Kankakee Arch and the Findlay Arch and where the Anna earthquakes occurred.

The only significant regional fault is the Bowling Green Fault which is approx 35 mi from the site at its closest point. We do not believe that the Anna earthquakes are related to displacements along the Bowling Green Fault, because the southern extremity of this fault is reported to be near Findlay, Ohio, approx 50 mi from Anna, and the Anna area is not in line with the general direction of this fault. No evidence of dis- ~

placement along this fault younger than the Silurian period has been found during the geologic study. We believe that the ,

Eovling Green Fault is inactive.

The site region is adjacent to the stable Canadian Shield. Some seismologists, e.g. Richter (Richter, 1959), in-dicate that stable shields are often fringed by belts of moderate seismicity with occasional strong earthquakes. There is no indication from historic earthquakes that the site region is in one of these belts.

The site region is part of the Great Lakes region, in which earthquakes may be caused by bedrock rebound subsequent to retreat of the glaciers. Only two relatively small earth-quakes (epicentral intensity MM VI, magnitude 5) may be explained by this cause.

The site is underlain by the Findlay Arch which formed and ceased its formation prior to the Palezoic era. However, considering the earthquake epicenter map of the region, there appears to be a concentration of epicenters of small to moderate earthquakes on the Findlay Arch; see Fig. III-3. There are no topographic expressions at the site which could possibly be related to earthquakes. The subsurface investigation has not disclosed sny fractures which could be interpreted as resulting from tectonic movements.

2. Conclusions The regional geologic study has disclosed regional geologic features which affect or may affect the seismicity of the region or localized areas in the region. The Findlay Arch, which may be associated with small to moderate earthquakes,

! underlies the site. The Ohio-Indiana Platform affects the Anna l area but not the site locality. The Bowling Green Fault, approx 35 mi from the site, is believed to be inactive. The site region and locality lie in the fringe of the Canadian Shield

/

2C-28 c

-~ . . . . . .

d (s- and, vnile there is no evidence that they are in a seismically active belt, they may be subjected-to rebound due to glacial retreat.

The local geologic study, the examination of the local topography, and the site subsurface investigation have not disclosed any local geologie features which would tend to affect ths seismicity of the site locality. No local faults have been recognized and none are believed to exist.

The seismicity of the site may be affected by the Findlay Arch. It is not af-fected by other regional geologic structural features and it is not affectei by local l1 l

geologie structural features.

D. SELECTION OF SYNTHESIZED EARTHQUAKES

1. General Two synthesized earthquakes are recommended: the maximum probable earthquake and the maximum possible earthquake. The maximum probable earthquaka (smaller earthquake) is a synthesized earthquake which induces the maximum grocnd motions into rock-like -

material at the site, which, under the presently known existing geologic conditicns, are considered to have a reasonably small chance of occurring during the life of the nuclear ,

power station. The maximum possible earthquake (larger earthquake) is a synthesized earthquake vbich induces the maximum ground motions into rock-like material at the site, y which, under the presently known existing geologic conditions, are considered to be capable of occurring. The maximum probable (smaller) earthquake is primarily selected on the basis of the historic earthquakes with consideration, at least in a qualitative way, of the pro-

' bability of occurring. The maximum possible (larger) earthquake is primarily selected on

. the basis of structural geologic features.

. These two synthesised earthquakes are initially selected independently, on the basis of seismology only. If required, the maximum ground acceleration of the maximum probable (smaller) earthquake is modified to te censistent with the type of iesign analysis, specifically the most severe loading combinations, presently accepted in prac-tice. The presently accepted most severe loading combinations require that the maximum ground acceleration of the smaller earthquake be no less than one half the maximum ground acceleration of the larger earthquake. Consequently, if th'e maximum ground acceleration of the smaller earthquake is less than one half the maximum ground acceleration of the larger earthquake when these synthesized earthquakes are selected on the basis of seismology only.

. the maximum ground acceleration of the smaller earthquake is raised. Because an accuracy greater than C.01 gravity is not realistic, the maximum grcund acceleration of the smaller earthquake is conservatively rounded off from one half of the maximum ground acceleration of the larger earthquake to the next highest 0.01 g when the maximum ground acceleration of the larger earthquake is an uneven number of 0.01 g.

On the basis of seismology, there is no relationship between the values of the maximum ground accelerations of the r.aximum probable (smaller) earthquake and maximum ,

possible (larger) earthquake. Actually, in the west coast area of the United States, 2 I which'is a zone of relatively high seismietty, both the great number of historic earth-l quakes and extensive seismologic and geologic studies have led to a relatively good knowledge of the seismicity of the area. For a vest coast site, the parameters of the smaller earthquake are often not much smaller than the parameters of the larger earthquake. _,

In the middle western part of the United States, the seis=icity generally is relatively i lov and the -small number of historie earthquakes has not been conducive to extensive seismologic studies. To ecmpensate for.the limited seismologie data available in the middle vest, a conservative approach is taken when selecting the parameters of the larger

. earthquake, and the resulting parameters may be much greater than the parameters of the smaller earthquake. The selection of the synthesized earthquakes is based on the ESSA Seismic-Risk Map, the records of the historic earthquakes, and the regional and local gec-logic structural features. The selection of an earthquake for structural analysis includes the selection of the following parameters 2 maximum ground acceleration, maximum ground velocity, maximum ground displacement ' and total duration of the ground motions. An accelerogram of the ground motions (i.e., a plot of acceleration versus time) is also selected.

Several authors have developed equations (e.g.. Gutenberg et al 1942; Hershterger-1956; Esteva et al, 196h) and charts (Seed et al,1969 ) which nay be used as a guide for the determination of the earthquake parameters. In addition. Profes sor 3. M. Newmark (Newmark et al, 1969, Table I) has suggested standard relative values of maximum grount acceleration, velocity, and displacement.

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PC-29

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2. Selection of the Characteristics of the Maximum 2 frobable (Smaller) Earthquake on the Basis of Seismology

a. Selection of maximun horizontal ground accel-eration, velocity, and displacement -

~

The study of the site seismicity suggests the selec-tion of several earthquakes for the determination of the param-eters of the maximum probable earthquake: a great, distant earthquake (earthquake A), a moderately strong earthquake in the Anna area (earthquake B), and a local earthquake (earthquake C).

Earthquake A. Earthquake A is conservatively modeled after the New Madrid, Charleston, and St Lawrence Valley earthquakes. The parameters of these earthq'uakes _ and those of

-)

earthquake A are given below.

)

Epicentral Distance from intensity epicenter to Earthquake MM Magnitude site, mi New Madrid XII (12.0) 8 h70 Charleston X (10.0) 7.1 - 7.7 620 1

St Lawrence Valley IX-X(9.5) 6.h - 7.3 770 Earthquake A XII (12.0) 8 h00 Earthquake B. Earthquake B is conservatively modeled after the Anna earthquakes. The parameters of the stronger Anna earthquake (that of 9 March 1937) and those of earthquake B are given below.

Epicentral Distance from intensity epicenter.to Earthquake MM Magnitude site, mi Anna VII - VIII(7.5) 6 100 Earthquake B VII - VIII(7.5) 6 75 f

I

)

[

2C-30

duration of approx 30 see and that the duration of its strong motions be approx 3 sec.

, k. Recommended Parameters for the Synthesized Earthquakes 1

Because the maximum ground acceleration of the maximum probable (smaller) earthquake selected on the basis of seismology ,,

(i.e., 0.06 g) is less than one half the maximum ground accelera-

tion of the maximum possible (larger) earthquake (i.e., 0.15 g),

we raise the maximum ground acceleration of the smaller earth-quake to 0.08 g. The recommended parameters for the synthesized earthquakes are given in Table III-h. '

E. ASEISMIC DESIGN

1. General Approach All features of the nuclear power station necessary for continued operation are designed to remain functional under the motions induced by the maximum probable earthquake (the smaller earthquake). All features of the nuclear poner station z necessary to protect the health and safety'of the public and assume the conservation of the environment are designed to re-main functional under the motions induced by the maximum pos-sible earthquake (the larger earthquake).

The selection of the parameters of a synthesized earthquake and the development of the response spectra, depends, among other factors, upon the manner in which they are used for design.

2. East-West Accelerogram of 31 October 1935 Helena Earthquake The accelerogram of the east-west component of the i Helena, Montana, earthquake of 31 October 1935 is selected for '

the development of the.accelerograms of the maximum probable and maximum _possible earthquakes. A record giving acceleration  !

versus time was obtained from the original accelerogram (Cloud, I personal communication). _ Appropriate base line corrections were '

applied and-the record was redigitized at intervals of 0.01 see 1 for a duration of 10 see by Dr. I. M. Idriss and provided by Professor H. Bolton Seed of the University of California. l j

The development of the accelerograms for horizontal ground motions for both the maximum probable and maximum pos-sible earthquakes is described in Table III-4. To obtain the I accelerogram of the horizontal ground motions of the maximum 2C-35

3

)

probable earthquake, the duration of this Helena accelerogram ic increased from 10 see to 30 see and the accelerations of this Hclena accelerogram are multiplied by the ratio 0.08/0.15

! This is the ratio of the maximum ground acceleration of the

, maximum probable earthquake to the maximum ground acceleration of this Helena accelerogram. To obtain the accelerogram of the 4

herizontal ground motiens of the maximum possible earthquake, the accelerogram of the horizontal ground motions of the maximum probable earthquake is multiplied by the ratio 0.15/0.08,

3. Basis for Selection of the 31 October 1935 Helena Earthquake The Helena earthquake of 31 October 1935 is selected -

because many of its characteristics are similar to those which would be expected of the maximum possible (larger) earthquake.

The predominant period of the Helena record is equal to the

-predominant period that would be associated with the maximum possible (larger) earthquake which is estimated from graphs recently published (Seed et al, 1969). These graphs indicate that the predominant period for a magnitude 6 local earthquake is about 0.25 sec. Another accelerogram with a similar pre-dominant period is that recorded at Golden Gate Park during the 22 March 1957 San Francisco earthquake.- However, an exam- '

1 ination of the resnonse spectra of the Helena and Golden Gate ,j records indicates that the spectral values of the Helena record are higher than those of the Golden Gate record for long periods (i.e., longer than 0 5 sec; see Fig. 111-7). Such a character-istic is expected from earthquakes in the site region. Thus, the Helena record provides a more applicable and more conserva-tive estimate of the anticipated ground motions at the site than would the Golden Gate record.

The characteristics of the Helena record are more applicable to the site than are the characteristics of the re cord obtained at El Centro during the 18 May 19h0 Imperial Valley ear.thquake or the record obtained at Taft during the 21 July 1952 Kern County earthouake. Both the Imperial Valley and Kern County earthquakes were stronger than the selected maximum possible (larger) earthquake. Their accelerograms were recorded by soil supported seismographs, whereas the Helena accelerogram was re-l corded by a rock supported seismograph; thus, the Helena record is'more applicable for estimating ground motions of competent rock.

The characteristics of the proposed ground motions and those of the Helena, Golden Gate, Taft, and El Centro records together with the known site. conditions at the recording stations are compared'in Table.III-5 J'

2C-36

h. Calculation of the Response Spectra of the East-West Component of the 31 October 1935 Helena Earthquake Significant discrepancies were found among published response spectra of the Helena earthquake. For example, for zero dampi g, one response spectrum gave the maximum acceleration (i.e., 1.5 g) and maximum velocity (i.e., 20 in/sec) for a fre-quency of h.5 cy/sec; whereas another response spectrum gave the maximum acceleration (i.e., 0 9 g) for a frequency of 5 5 cy/see and the maximum velocity (i.e., 12.5 in/sec) for a frequency of 2 5 cy/sec. y We have calculated the response spectra of the selected accelerogram of the Helena earthquake for several damping ratios by means of a program recently developed at the University of California (Idriss et al, 1969). These response spectra were checked and found very similar to the response spectra of the east-vest component of the 31 October 1935 Helena earthquake

_ calculated independently at the Massachusetts Institute of Tech-nology (Whitman, personal communication). A comparison between ,

these two independently calculated response spectra is shown in "

Fig. III-8.

5 Recommended Resnonse Soectra The recommended response spectra for horizontal ground motions of the maximum probable earthquake' for damping ratics of 0, 0.005, 0.01, 0.02, 0.05, and 0.1 are plotted in Fic. III-5.

The recommended response spectra for horizontal ground motions of the maximum possible earthquake for damping ratios of 0, 0.005, 0.01, 0.02, 0.05, and 0.1 are plotted in Fig. III-6.

These response spectra vere developed for the Davis- l Besse Station by considering the Helena response spectrum and sev- '

eral often used average response spectra. Average response spec-tra are developed from several response spectra of individual earthquakes. Consideration of average response spectra is made to remove the peculiarities o f any response spectrum calculated from a single earthquake. For example, the response spectrum of the Helena earthquake has a valley (low response) for frequencies in the vicinity of 2 cy/sec; for these frequencies the Helena response is not used and average response spectra are considered.

The recommended response spectra are developed from the ground motions selected on the basis o f s eismology , using ,

Professor N. M. Newmark's suggested method (Newmark et al, '

op. cit., p. B-h, h3 to h5), except that two modifications are made.

Modification one. In the case of the response spectra of the horizontal ground motions induced by the maximum probable

[ (smaller) earthquake (Fig. III-5), the spectral accelerations are raised for all damping ratios for frequencies greater than 1l2 cy/see so that they are not smaller than 0.08 g.

2C-36a

Modification two. The spectral amplification factors suggested by Prof. Newmark (Newmark et al, op. cit., Fig. 2) are T 2

m dified for two reasons (1) the maximum ground accelerations are not reduced by the factor 0.67 as it is suggested by Prof. Newmark when the foundation conditions consist of competent rock; and (2) consideration is made of the response spectrum of

, the Helena earthquake.

The recommended maximum ground accelerations were not reduced by the factor 0.67 before developing the response spectra because a comparison of the Newmark reduced response spectra and the Helena response spectra showed that the Newmark reduced response spectra tre below (less conservative) the Helena response spectra. Plotted in Fig. III-7 are the Newmark response spectra (unreduced and reduced) and the Helena response spectrum for zero damping. The Helena response spectrum lies ,

between the two Newmark response spectra.

The amplification factors are given in column (9) of Table III-6. These amplification factors were used for the dev-elopment of the recommended response spectra of the synthesized earthquakes shown in Fig. III-5 and III-6.

Table III-6 contains amplification factors for spectral accelerations, velocities, and displacements determined by dif-

^

ferent approaches for several damping ratiqs. Amplification factors for spectral acceleration at a high frequency (i.e.,

5 cy/sec) are listed in part (a) of the table. Amplification factors for spectral velocity at a medium frequency (i.e.,

1 cy/sec) are listed in part (b) of the table. And, amplifica-tion factors for spectral displacement at a low frequency (i.e., 0.2 cy/sec) are listed in part (c) of the table.

Column (1) of the table contains the damping ratios for which the amplification factors were calculated.

Column (2) contains amplification factors calculated for an earthquake of 30-see duration using rules developed by Professors L. Esteva and E. Rosenblueth and reported by Professor R. Whitman (Whitman, personal communication). Column (2) is given for comparison only, because these rules were developed for distant earthquakes not quite applicable to the site.

j Column (3) contains amplification factors calculated l from the curves plotted in TID 702h (USAEC, 1963, p. 1.3D, L ' Fig. 1.21). These curves were developed by Professor G. Housner on the basis of the relative velocity spectra of several earth-quakes.

.)

2C-36b

MAXIMUM PROBABLE EARTHQUAKE (SMALLER l'ARTHOUAKE)

1. Horizontal Ground Motions Maximum ground acceleration: 0.08 gravity l2 Maximum ground velocity: 2 in/sec Maximum ground displacement: 1.33 in.

Total duration: 30 see Time-history accelerogram. developed from the accelerogram of the east-west component of the Helena, Montana, earthquake of 31 October 1935 as obtained in digitized form from Professor H. Bolton Seed of the University of California, in the following manner: (a) add five timer to the end of the accelerogram the portion 6.0 see to 10.0 see to increase the duration of the accelerogram from 10 see tc 10 + 5 (10 - 6) = 30 sec; (b) multi-ply the accelerations of the resulting accelerogram by 0.08/0.15 -

2. Vertical Ground Motions

• Maximum vertical ground motions are 2/3 of maximum horizontal ground motions of the maximum probable earthquake.

1 MAXIMUM POSSIBLE EARTHQUAKE (LARGER EARTHQUAKE)

1. Horizontal Ground Motions .

Maximum ground acceleration: 0.15'g Maximum ground velocity: 5 in/sec Maximum ground displacement: 3.33 in.

Total duration: 30 see Time-history accelerogram: calculated from that of the hori-zontal ground motion of the maximum probable earthquake by multi-plying the accelerations by 0.15/0.08 l2

2. Vertical Ground Motions Maximum vertical ground motions are 2/3 of maximum horizontal ground motions of the maximum possible earthquake.

1

( RECOMMENDED PARAMETERS FOR THE SY' THESIZED EARTHQUAKES WCA 68-192 Table III-4 2C-h2

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'T .mf, ynec X* Ratio of critical damping RECOMMENDED RESPONSE SPECTRA FOR HORIZONTAL GROUND

[ MOTIONS OF MAXIMUM PROBABLE EARTHQUAKE (SMALLER EARTHQUAKE)

FOR SEVERAL DAMPING RATIOS WCA 68-192 Fig. III-5 2C-47 (Amendment 2)

_