ML17037C156

Letter Regarding a Geological Report and a Request for Examination and Submittal of an Independent Opinion

ML17037C156
Person / Time
Site:	Nine Mile Point
Issue date:	02/21/1964
From:	Ewart J Niagara Mohawk Power Corp
To:	Sutton G Lamont Geological Observatory
References
Download: ML17037C156 (14)

Text

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~ / S NIAGARA MOHAWK POWER CORPORATION NIAGARA MOHAWK BUFFALO 8, N.Y.

February 21 1964 Dr. George H. Sutton Lamont Geological Ob'servatory Palisades, N. Y.

Dear Dr. Suttori'~

Confirming our telephone conversation'of February 21, Mr. Joseph Fischer will hand you a copy of the Dames and Moore geological report for our Nine Mile Point Nuclear Power Station on Monday, February 24. We request that you examine this report and render an independent opinion of it. Please feel free to comment, as an expert, in any area you wish but we would like your opinion in the following specific categories:

l. Is there sufficient evidence in this report that this site is not subject to Zone 3 earthquake rating, and do you agree with the ground acceleration as specified.? '"'.

Do you agree with the historical seismological data of the site regarding the magnitude of the shocks at location of the epicenter?

3. What'would you consider to be the probable maximum magnitude of shock that might occur in the general area within a 100-mile radius of the site during the next 200 years?

4. What do you consider the credible magnitude of shock that might occur in the general area during the next 200 years?

J We have worked very closely with Mr. Fischer on this project, so if you need further clarification of the questions listed herein, please feel free to discuss them with him.

As I indicated to you, we would like to have your reply as early as possible in order that we can incorporate it as a part of our preliminary harards summary report which is due on April 1 ~

Very truly yours, J. N. Ewart Chief System Project Engineer 4

~P ALPINE GEOPHYSICAL ASSOCIATES, ING.

55 Oak Street, Norwood, New Jersey ~ Cable: "ALPGEO" ~ 201-768-8000 March 10, 1964 Mr.. 3. N. Ewart Chi,ef Systems Prospect Engineer Niagara Hohawk Power Corporatian 535 4/ashington Street f

Buf alo, New York Our File 3S-714

Dear Mr. Ewart:

Following ls a summary of'y opinions based on a critical reading of'Part II, Section C, Engineering Seismology; Site Evaluation Study, Proposed Nine Hile Point Nuclear Power Plant; near Oswego, New York; for the Niagara Mohawk Power Corporation" prepared by Dames and Maara.

In answer to the four specific questions you raised in your letter of 21 February 1964:

(1) I believe that there should be suf'flclent evidence in the cited report by Dames and Moore (hereafter called 0-M report) that the Oswego, New York site is not sub)ected to Zone 3 earthquake rating and that the specified ground accelerations are reason-able.

(2) The historical seismological data regarding in-tensities and magnitudes in the region appears to be accurately presented ln the D-M report.

(3) The probable maximum magnitude shock that might occur in the general area within 10D mile radius of'he site during the next 2DO years ls H ~ 5.0 ta 5 7 (maximum intensity I, ~ 7 to 8).

(4) The credible maximum magnitude shock that might occur within 100 mile radius of the site during the next 200 years i,s M ~ 7 ~ 0 (Maximum intensity lo ~9) ~,

Although there can ba na absolute guarantee that a very large shock will not occur in the vicinity of the sita, lt appears to be favorably located with respect to seismic risk.

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Hr. 3. N. Ewart March 10, 1964 Historically, only three shocks of intensity I ~ 5 or greater have occurred within 100 miles of the sita; one near 50 miles distant and two near 100 miles distant. There are no known active faults in the region and it is underlain by relatively undeformed lower Paleozoic rocks with high mechanical competence.

Seismicity in this general region seems to be related to the St. Lawrence Valley, marginal to the stable Canadian Shield, and to the ancient Appalachian Mountain system. Host of the activity related to the St. Lawrence Valley is northeast of the site while the activity related to the Appalachian system passes well east of the site in the general NE-SbJ trend. Similar zones of relatively minor seismic activity are common throughout the world at the margins of stable shield areas and along mature (ancient) mountain systems.

The occurrence of several earthquakes west of the site in the general vicinity of Buffalo, New York, requires some caution in assuming that the historical activity within 100 miles of the site vill be representative of the activity in the next 200 years or so. Also, I do not believe that the statement that the seismicity may be decreasing as a result of slackening glacial rebound is completely )ustified, since, as mentioned above, similar regions which have not 'been glsciated in the past few thousand years exhibit similar seismicity.

In order to obtain some statistical reliability I considered a region of radius 200 miles surrounding the site.

This region has 4 times the area of the zone being considered.

The following table lists the number of historical earth-quakes with maximum intensities equal to or greater than the stated value in this region:

nuabar ~Intana it 41 V (or greater)

VI (or greater)

VII (or greater)

VII1 If the seismicity within 100 mile radius of the site were equal to that of the larger region these numbers would be divided by 4. A conservative estimate taking into consideration the actual historical distribution of shocks would be to divide by 8. (The precision of the data makes any small correction

'I Mr. J. N~ Ewart March 10, 1964 for the time factor, 200 years span includes moat of the shocks, relatively unimportant.) On this basis one earthquake of maximum intensity I, ~ 7 might be expected within 100 miles in 200 years. Ho~ever two intensity 8 earthquakes have occurred at a distance only slightly greater then 100 miles from the site.

Since very few magnitudes of larger earthquakes in this region have been measured directly, it is necessary to relate intensity data to magnitudes. The formula, M ~ 2/3 Io 1.7 log h - 1.4 where M is Richter Magnitude I, is maximum Modified Mercalli intensity h is focal depth in kilometers, obtained by Harnik as an average of observations by several investigators in various regions, was used for this purpose.

In a very recant study by Isacks of a 300 km radius area surrounding northern New Dersey this relation was found to be reliable for relatively small earthquakes using a focal depth of about 10 km. Previous studies of larger earthquakes in this general region indicate greater focal depths (up to 60 km).

On the Seismic Zoning Map of the 1958 Uniform Building Coda, prepared by the U.S.C.E G.S., the proposed site falls north of a line separating Zone 1 (to the south) from Zone 3. The lines on this map are necessarily some~hat arbitrary and should be used only as a general guide, especially near zone boundaries. The immediate vicinity of the site should be considered mora nearly Zone 1 or, perhaps, Zone 2 than Zone 3.

Sincerely yours; George HE Sutton Assoc. Prof. of Geology Consultant

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GE pproved by:

bl a er C. Beckm ann, President ALPINE GEOPHYSICAL ASSOCIATES) INC ~

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THE UNIVERSITY OF THE STATE OF NEW YORK THE STATE EDUCATION DEPARTMENT AI.SANYINEW YORK I2224 NCW YORK STATC NVSCVN ANO SCICNCC SCRVICC ASSISTANT COMMISSIONCR April 23, 1968 Dames and Moore 100 Church Street New York New York 10017 Gentlemen: Attention: ~Jose h A. Pinches In a telephone conversation with Fred Fox yesterday, he indicated that your company is presently concerned with the trend of struc-tural and seismic lines in New York State, particularly with re-spect to the Oswego area.

I Although do not consider myself an expert in the area of geo-physics, I am quite familiar with the structural trends in New York and have had occasion, within the last two years, to plot areas of seismicity within the State. There is no indication to me that such a belt passes through or near the Oswego region.

I believe that seismi,c activity in the St. Lawrence lowlands is largely the result of shallow focus movement resulting from reactivation along fault lines caused by ice overloading duri.ng the glacial period. The glacial rebound in the last 10,000 years has been in the nature of 550 feet in the area of Montreal and progressively less southward into New York State. Other structural trends in New York State are northeast-southwest lineaments which transect the Adirondacks, roughly east-west folds in the Finger Lakes area and southwest, and northwest-southeast trending lines which appear on Nimbus photos cutting across western New York in the Buffalo and Ni.agara Falls areas.

None of these indicate a trend running from the St. Lawrence lowlands southward through Oswego and thence across the State, and I do not believe that any exists.

DAMES &YORK MOORE NEW RECEIVED Sincerely yours, G. Broug on g(j "I oo Assistant Commissioner (Acting) cc: F. Fox CMII I CC Reise I JTO I CPS NC I WJM L,C I I9 I TET RSE I.JA R RM C'TM AR IJW OMIT JMH J4

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NIAGARA MOHAWK POWER CORPORATION .

NIAGARA ~) MOHAWK Ittllt&,

BvvvAI.a, NEw YoRK $ 4203 May 31, 1968

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Dr. Jack E. Olive'r I amant Geological Observatory p"-~ Palisades, New Yox'k 10964 Lt Doax Dr. Oliver:

~ g Eaxly in '1964 we contacted Dr. George Sutton, wha was thon associ-'ted with tho Lamant Geolagical Observatory, far independent review of the '

preliminary geological report px'eparod by Dames and Moore for our Nine

~ Milo Point Nuclear Station. %'e now fool it is deoirablo to obtain a, similar " .

independont review af a subsequent Dames and Mo'ox'e report entitled "Seiomic Geology, Nine Mile Paint Nuclear Power Plant, Noa'r Oswego, Now York." Vle have ax'x'anged fox Mr. Joseph Fischer to doliver a copy of this report to the Observatory and x equeot that you or a member of youx

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staff review it, as an expert, and comment in any area you wish. However,',

we would like'opinions

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in the following specific areas: 4

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(1) The passible line cannectio'n of opicenters south- ,r weotwax'd fram the St. Lawrence Rivex'alloy.

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(2) Lo there any reason predicated on new information which would indicate that the 11 pex'cent anticipated m~mum ground acceleratian previously adapted ao a design valu'e should be changed'l I

IVe have worked very claooly with her. Fischor on this project sa if you or your "aosaciateo naod further clarification of this wox'k, p)ease feel free ta diocuoo it with him. Wo would'appreciate a reply by the fixot week af July at the latest for consideration in meetings scheduled with the Atomic Energy Commission. t Vary truly yours,

~ N. Ewax't Chief Syoto rojoct Enginoor JNE/jfw f.

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s Lamont Geological Observatory 'of Columbia University ~

Palisades, N Y.. 10984 t

Cabfs Addrassr Lamont, Pallsados, fsfsw York Stats Coda 0'f4, ELmwood 0-0000 June 26, 1968 Mr. J. N. Ewart Chief Syst;em Project Engineer Niagara Mohawk Power Corporation Ehxffalo, New York 14203

Dear Mr. Ewart:

Dr Oliver forwarded your letter of May 31 to me and requested that; I handle the review of the Dames and. Moore report entitled. "Seismic Geology, Nine Mile Point Nuclear Power Plant near Oswego, Nev York". Accordingly .

I contac+ed Mr. Joseph Fischer and arranged with him a meeting with Hr. Fred Fox. I received the above-mentioned report fron Mr. Fox and discussed the work with him.

read the report; carefully and further discussed several points with ttfr. Fox and Mr. Fischer. The following are ~

comnents that I have concerning the report.

'it I agree with the basic argument of the report that is not reasonable to extrapolate the relatively h'.gh level. of se~smicity of the St. Tawrence region to the area of the Oswego site. In particular, I think that the evidence for +he correlat."on between the high seismicity of the New Madrid enr3. St. lawrence regions with localized fault;ed structures of Paleozoic or later ages is convincing.

This evidence reasonably indicates that, even if the align-ment of epicenters is not an artifice or is not fortuitou tbe levet oi,'ei,sisiclty varies slgnlfi.cantly along tbe supposed feature and appears to be controlled by '.local geological structure.

I see no problem with the estimation of O.ll g for the maximum ground accelerat;ion". I suggested to Mr. Fischer that he consider, as a possible alternative, the effect;s of an earthquake the size of the Attica Earthquake located very close or at the site in question. Yw. F.'.scher inform-ed me that. this would not sigrificantly increase the estimated acceleration.

In gener@3., I agree with the basic conclusions of the report. Please le~t me know discussion of some part< euler noints.

'f you wish further. deta11ed Sincerely yours 3 y n L. Isacks

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