ML20062K964

Chinnery Answers to Applicant Interrogatories Re Seismic Issues.Affidavit to Be Forwarded Shortly.Certificate of Svc Encl

ML20062K964
Person / Time
Site:	Seabrook
Issue date:	01/06/1981
From:	Jordan W NEW ENGLAND COALITION ON NUCLEAR POLLUTION, SHELDON, HARMON & WEISS
To:	PUBLIC SERVICE CO. OF NEW HAMPSHIRE
References
NUDOCS 8101090306
Download: ML20062K964 (25)

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UNITED STATE 3 OF AMERICA o. 8 Ott;Q[theSeefef,7y i NUCLEAR REGULATORY. COICIISSION L. 37, Service d N

BEFORE THE ATOMIC SAFETY AND LICENSING APPEAL BO , P

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In the Matter of )

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.PUBLIC SERVICE COMPANY OF ) Docket Nos. 50-443 NEW HAMPSHIRE, et al.

) 50-444 (Seabrook Station, Units 1 and 2) )

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NECNP RESPONSES TO APPLICANT'S INTERROGATORIES o

Attached are Dr. Chinnery's answers to the Interroga-tories posed to NECNP by Applicant Public Service Company of New Hampshire. Dr. Chinnery's affidavit is still being i

prepared and will be forwarded shortly.

Respectfully submitted,

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William S.fJordan, III . y Harmon & Weiss 1725 I Street, N.W.

Suite 506 Washington, D.C. 20006

(202) 833-9070 Counsel for NECNP Dated: January 6, 198) 8101090 %

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Lk N and east of longitude 72"'.., together with that part of Massachu-setts and the Atlantic Ocean bounded by latitudec h2 and h3 N, and longitudes 69.5 and 71.5 W.

Reference:

1. Chinnery, M. A. and Rodgers, D. A., Earthquake statistics in

- Southern New England, Earthquake I!otes, volume hh, pp.89-103, 1973

I have not retained tne workaeets used in the preparation of my 197h testimony. However, subsequent to then I have reworked the problem in more detail and published the results (see reference 1 belev). That -

paper contains full details of the data catalogs used, the nethod of extraction of the data plotted, and the areas selected for study.

Reference:

1. Chinnery, M. A., A comparison of che seismicity of three regions of the Eastern U.S. , Bulletin of the Seismological Society of America, volume 69, number 3, pp. 757-772,1979 I

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of the term " discrete seismic zone." In fact, there is no generally accepted definition for such a zone in the Eastern U.S.

In the absence of such a definition, it is difficult to define the boundaries of any seismic zone. My particular.

selections are certainiy not unique, and I do not ascribe any particular properties to the boundaries of the areas that I selected. Subject to the response to Question 15, I do not expect that choice of different boundaries would make a substantial change in the results.

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this r.ay not be entircl; 7alid, but ce cow 30 little about, any p0csible lack of stationarity that we are forced to make this assumption.

Within any given area, a record of earthquake activity over a very long period (theoretically infinite) vill completely define the long term characteristics of the' seismicity in that sone. Records or a i

shorter length vill lead to estimates for these long term characteristics.

We vould clearly like to have as long a record as possible in each zone, but such a record is only useful in so far as it is relatively complete. It is therefore reasonable to use as much of each catalog as appears to be reliable. We attempt to determine the number of events at each intensity (or magnitude) value per year. Comparison of different areas does not require that the sane lengths of record be used, if the stationarity assumption is valid.

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- . T This report is not available to me, and my letter quoted only from recollection. However, this statement has appeared in the following places:

1. Deposition of Donald E. Vandenburgh, containing ansvers to interrogatories propounded to the Public Service Company of New Hampshire by Elizabeth H. Weinhold, Answer 15

2. Applicants' Direct Testimony before the Atonic Safety and Licensing Board, page 15, line 12.

Both statements refer to the occurrence of Intensity VIII on the bedrock of the Seabrook site. In view of the requirement of NRC criteria 10 CFR Part 100, Appendix A, that the largest earthquake associated with the seismotectonic province including the site be ascumed at the site, these statements are directly comparable to the reference from my letter quoted in the question.

province either in 10 CFH Parr, 100, Ap1'endix A, or in the scientific literature, I cannot answer this question directly.

The Appendix A definition is "a region of the North American conti- ,

. l nent characterited by a relative consistency of the geologic structural features contained therein". In my opinion, this definition is so vague e

as to be vorthless.

If_a province can be defined that has uniform sciemicity character-

, istics (I do not necessarily argue that this can be done, or that this corresponds to the Appendix A definition), then data from any portion of the zone vill define the characteristics of the whole zone. Using this b-approach, the Boston-New Hampshire seismic zone (see question 2) may be regarded as a portion of a larger undefined province, and validly used to estimate risk at the Seabrook site.

The above approach is valid if regions of uniform seismicity exist.

In this context, we must define the word " uniform" in the following way:

Suppose that the long term characteristics of the region can be suzzarized by the frequency-magnitude relation:

log U = a - bM vhere H is the cumulative nunber or enrthqusken with nry;nitude M or-g 'ite: po t- u, : ' m, .- >'! b - em ;t: m. 'avm aniformity nu '

Ir rei; tens of uniforn seiscicity do not, exist, then nat only is the sb ave approach not, uliti, but nica e.ny use or- ni.scic or tectonic provinces becomes meaningless.

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Ihe bacia for cy spiniona expre sed in que:st. ion 12 ::ac developed from reading the scientific literature, various informal discussions with seismologists, and participation in the study " Seismic IInzard Analysis Solicitation of Expert Opinion", conducted by TERA Corporation.

None of my published papers have addressed the problem of the definition of a " tectonic province".

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the estination of the se 2 saic rio., at . . . _ - .3cabroa. site is not dependcat on the particular choice of a " tectonic pro-vince." However, the choice of " tectonic province" may influence the size of the risk associated with this site.

The Boston New Hampshire zone is not to be identified with the " tectonic province" containing the Seabrook site. See response to Question 12.

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1. Definition of the Safe Shutdown Earthquake.

A?pendix A defines the SSE using the terms " based on an evaluation of the maxinum earthquake potential", and "the maximum tibratory ground motion for which certain structures, systems and compsnents are designed to rema!.n functional". This definition has to be interpreted as the largest earth-quake possible during the lifetime of the structure, at a 100% probability level.

In my opinion, the current state of knowledge in seismology is not sufficient that such an absolute declaration can be made, and I do not anticipate that this vill change in the foreseeable future. To put this l another say, at any site we do not know enough that we can completely l

rule out the occurrence of an intensity XII earthquake, even though we I

think it may be extremely unlikely.

i If this is so, then associated with any choice of SSE is a level of risk (or probability that it may be exceeded). In my view, Appendix A should specify an annual probability level which constitutes an acceptable level of risk.

For example, the definition could be phrased as follows:

"The Safe Shutdown Earthquake shall be that carthquake which shall be established as leading to actual failure of critical plant components a . th an annual probability not exceeding 10~ . The conputation of the f.iluu p e9 + 1 L t ,, -Ki

vith this definition:

(i) the term " relative consistency" is completely ambiguous.

(ii) there is no set of "tectonie provinces" in the Eastern U.S.

that is accepted by a majority of seismologists and geologists; furthermore, I do not anticipate that agreccent will be reached in the foreseeable future.

(iii) the context in which this definition is needed is in'the description of the distribution of earthquake occurrence, i

In the Eastern U.S., and in parts of the Western U.S., there is no clear correlation between geologic structure and earth-quake occurrence. We do not know which features of Geologic structure are related to seismicity, and which are not.

In my view a more useful definition of a " tectonic province" would be as follows:

"A tectonic province is a region of the North American continent characterized by a uniform distribution of earthquakes, in which an carthquake of any given sine has the same probability of occurrence at all points within the province. The uniformity of the earthquake occurrence in any given tectonic province shall be demonstrated and Justified using all available seismolo6 I cal and geological information.

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region shall be not less than 100 kn, and shall be selected using all available seismological and geologi-cal information."

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hard ta prmee or tect, and nei ge:arall;. acceptcl by the ccientific community.

2. The historical record of earthquakes in this area is a very unsatis-factory data set. The completeness of the record is a complicated function of location, time and maximum epicentral intensity. Our knowledge of this function is minimal, and any interpretation of the record has a strong subjective element. It appears, for example, that modern instrumental recordings by the Rev England seismic network indicate a pattern of seismicity that is different in many respects from that indicated by the historical record.

3. Partly, perhaps, because of the weakness of the historical record, attempts to relate the overall pattern of earthquakes in IIew England to geological structures have been essentially unsuccessful. There is a strong suggestion that the 1940 New Hampshire earthquakes were related to the Ossippee Mountain ring dyke complex, but it is clear that most other events cannot be easily relate <1 to such well defined structures. Because of this, it is difficult and perhaps impossible to use the historical record to define where future earthquakes are likely to occur. The assumption that future large earthquakes vill occur only at the r.itea of hictorical lar6e events is very questionable.

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! In ny view, the above points are adequately cummarized by the l 4 ,

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] ctatement that "we know remari: ably little about earthquakes in the New {

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.i) A ev:.aer, aL,ic e s ure.u c. i.ne pt . .alli ty Lii a ; :!1e aedif.

acceleration would be exceeded during the lifetime of the structure.

(ii) A detailed evaluation of the engineering " safety factors" used in construction, i.e. a conservative estLnte of the probability that a critical component of the structure vill fail if subjected to en acceleration greater than the design acceleration.

(iii) An established " level of acceptable risk".

If the product of (i) and (ii) were less than (iii), then in my opinion the plant could be designated as " safe".

Let me add three points which emphasize my opinion:

a) I do not believe that the way to solve this problem is to seek for a Safe Shutdown Earthquake which is so large that its probability of occurrence is exactly zero. I do not think this can be done at present.

b) I feel that the safety factors built into the structure are an essential part of the assessment of seismic risk, c) I would not, perconally, require a prohibitively low " level of acceptable risk". In my view this risk should be made conparable to thoue ethe. rius im ah sa in . . plant (e.g. other natural

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questions. However, let me repeat the basic ideas here.

I'y arguments are brM nn one Ore-!::e, e::d this is that we do not i

know enough about earthquakes in the Eastern U.S. that we can (with 1005 [

certainty) state that an intensity XII could not happen r$t any site, even though we may often think it would be extremely unlikely.

Then, if 10 CFR Part 100, Appendix A is interpreted as requiring

the selection of an SSE which has a zero probability of occurrence during the lifetine of the structure, there is no alternative to making the SEE at all sites equal to the largest possible event, i.e. XII.

t However, I do not believe that 10 CFR, Part 100, Appendix'A requires such a drastic interpretation. My reading of these regulationn is that the SSE is an event which can be demonstrated as being extremely unlikely. ,

Unfortunately, this interpretation requires that " extremely unlikely" be j defined in some way, and the writers of Appendix A vere clear 3y unwilling j or unable to include this definition. This is a p/incipal change I ,,

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' vould like to see in Appendix A (see question 17).

All the above is independent of my so-called " theory of probability".

This only arises if try basic premire is accepted, and is one way to atte mt to esu ,te tho - oh ,bi l ~ + ! er. of n~'u ~en ce o f lit rge e irthquakea .

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(Seabrc.ok Station, Units 1 )

and 2) )

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CERTIFICATE OF SERVICE

'I hereby certify that copies of the "UECNP Responses to Applicant's Interrogatories," Iave been mailed postage pre-paid this 6th day of January, 1981, to the following parties:

Alan S. Rosenthal, Chairman Dr. John H. Buck Atomic Safety & Licensing Atomic Safety & I,icensing Appeal Board Appeal Board U.S. Nuclear Regulatory U.S. Nuclear Regulatory Commission Commission Washington, D.C. 20555 Washington, D.C. 20555 Frank Wright, Esquire Assistant Attorney General Assistant ^*torney General Environmental Protection Division Environmc L.1 Protection Office of the Attorney General Division State House Annex, Room 208 Office of the Attorney General Concord, New Hampshire 03301 One Ashburton Place Bonton, Massachusetts 02108

• Thomas G. Dignan, Jr., Esqbire Ropes & Gray Robdt A. Bachos, Esquire' 225 Franklin Street i n', ,!;, na ';n a , Spielr' , ' 'ilo E v an, ",v :ri ioettn 02210

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