ML20031C553
| ML20031C553 | |
| Person / Time | |
|---|---|
| Site: | Harris, Perry  |
| Issue date: | 10/01/1981 |
| From: | Davidson D CLEVELAND ELECTRIC ILLUMINATING CO. |
| To: | Tedesco R Office of Nuclear Reactor Regulation |
| References | |
| NUDOCS 8110070283 | |
| Download: ML20031C553 (10) | |
Text
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THE CLEVELAND ELECTRIC ILLUMIN ATING COMPANY P O box 5000 m CLEVELAND, OHIO 44101 m TELEPHONE (216) 622-9800 m ILLUMINAllNG BLDG e 55 PUBLIC idUARE Serving The Best Location in the Nation D:1wyn R. Davidson VfCE PRESIDENT CVSTEM ENGINEE A!NG AND CONSTRUCTION October 1, 1981 Mr. Robert L. Tedesee Assistant Director for Licensing Division of Licensing U. S. Nuclear Regulatory Ormnission Washington, D. C.
20555 Perry Nuclear Power Plant Docket Nos. 50-440; 50-441 Additional Nformation -
Geology-Seismology Questions
Dear Mr. Tedesco:
In a letter dated September 11, 1981, we stated that our responses for the Geology-Seismology questions for the Final Safety Analysis Report would be submitted by the end of October.
In order to ex-pedite the review process, the following two responses to the Geology-Seismology questions are submitted for your review.
It is our intention to incorporate these responses in a subsequent amendment to our Final Safety Analysis Report.
Very truly yours, Aifn f g g) -
Dalwyn W. Davidson Vice President System Engineering and Construction DRD: dip Attachment cc.
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230.2 You have concluded (FSAR, page 2.5-104) based upon lithologic and geoph_ysical (gravity) differences in the Western Ohio and Eastern Michigan area, that the Grenville Front constitutes a northward-tranding tectonic province boundary separating the Central Province on the west from the Eastern Stable Platform Province on the east. Although these differences are acknowledged, the Staff does not accept the Grenville Front ooundary as reflective of current tectonics because:
a.
Tine Grenville Front is an ancient (Precambrian) feature (Bass, 1960) found beneath a vcaeer of younger, little-deforme:1 Paleozoic sedimentary rocks, and still younger undefotued glacial debris, b.
The Findlay Arch, which probably forced during Devonian time (Fisher, 1976), straddles the Grenville Front and has apparently not been affected by later movement along the Front (Bayley and Muchlberger, 1968),
c.
Structural contours drawn on the Precambrian surface by Bayley and Muehlberger (1968) are not offset by the Grenville Front either in western Ohio or eastern Michigan.
Lacking convincing geologic and seisnologic evidence to the contrary, the staff reaffirms its previous position, which was taken in the CP Safety Evaluation Report, and will consider the Perry Nuclear Power Plant to be' located in *he Central Stable Region tectonic province within the meaning of Appendix A to 10 CFR 100.
Response
i A " tectonic province" is defined as "a region of the North American continent characterized by a relative consistency of the geologic structural features contained therein.
e The key to selection of a province then is structural features and since the purpose is to select a Safe Shutdown Earthquake, the occurrence and characteristics of earthquakes should be considered.
Ibst of the structures of the eastern United States are the reevlt of ancestral stress regimes no longer operative. Yet given certain conditions such as rigidity differences, gravity Fradients orientation in the present stress field, etc., it is these paleotectonic structures that move in the present strees field and cause earthquakes. The crystalline basement rock is rite seat of these earthquakes; material overlying the basement rock are g>nerally useful only where it reveals basement structure. The presence of Palec;oic rocks, as defining a province, is meaningful caly insofar as those rocks reveal basement features. Quoting from Eardly (1951):
"The central stable region of the United States is made up of a foundation of pre-Cambrian crystalline rock with a vencer of sedimentary rock.
The crystalline rock is both igneous and metamorphic in many varietics.
These rocks compose a complex undoubtedly 'similar to that of the great Canadian shield, and, therefore represent the extension of the shield southward into the United States, only covered there with sedimentary rocks.
The veneer varies grear:y in thickness from place to place. For the most part, the central stable region has suffered vertical movements, and broad basins and arches have formed. Some of the basins have more than 10,000 feet of strata in them, and in the cores of some of the arches the pre-Cambrian crystalline rock is exposed. Some of the arches and sharper uplifts are not expressed in the aurficial layers, and have been revealed only by drilling operations.
The arches, basins, and other structures of the central stable region, with few exceptions, formed during the Paleozoic era, and many of them yield evidence of a prolonged history of development."
The tectonic province (s) of the central stable region should be defined on the basis of crystalline basement rock structures not the " veneer" which covers them.
Soundaries of tectonic provinces may be faults or fault systems er they may represent changes in tectonic style, structure orientation and/or stress field orientation. Within this context it is believed that the Grenville front represents a fundamental boundary within the crystalline basement rock across which there ain distinct changes in structural style and orientation. These changes are manifest mainly in existing geophysical data, (gravity, aeromagnetic, and land magnetic) which reveal the basement rock.
1.
With regard to the question that the Findlay Arch straddles Grenville Front and has apparently not beca affected by later movement the following are cited as evidence to the contrary:
1.
Quick et al., 1976
" Bowling Green Fault - Case of Resurgent Tectonics?
The Bowling Green fault lies alcag the west flank of the Findiny arch and is a part of the Lucas-Monroe monocline. Detafled gravity and magnetic studies f r. Wood and Lucas Counties of north-western Ohio indicate that the trend of the fault parallels the west flank of a strong north-south-trending gravity and magnetic high, interpreted to represent an abrupt change in the character and structure of the basement rocks. This geophysically defined boundary in the basement can be traced northward across parts of southeastern Michigan and Lake Huron to the vicinity of exposures of the Grenville Front in Ontario, and southward across Ohio.
The correlation of this boundary with some Paleozoic structures that flank the Michigan basin is strong evidence that the boundary had been a zone of basement weakness which was reactivated during the formation of the Michigan basin. The association of petroleum accumulations with geophysical trends, such as the Albion-Pulaski-Scipio trend and the Lucas-Monroe Lenocline, illustrates the economic potential of detailed gravity and magnetic data in structural and tectonic interpretations."
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2.
Perry Nuclear Power Plant FSAR, Pages 2.5-17 and 2.5-18:
a.
" Bowling Green Fault This fault is a north trending, high-angle normal fault in northwest Ohio, 170 miles from Fae Perry Site (Quick et al.,
1976).
It has a downward disriacement of approximately 200 feet to the west. The Bowling Green fault is known to offset Silurian rocks and is possibly as young as Late Devonian (Quick, et al.,
1976; Rodgers, 1970; Ohio Edison Co., 1977).
Quick et al. (1976) suggest that the Bowling Creen fault is due to reactivation, during Paleozoic time, of Precambrian basement structures along the north trending Grenville Front."
II.
With regard to offset of the Precambrian basement along the Grenville Front, the following are cited:
1.
Ammerman and Keller, 1978:
4 "On the basis of these data, these authors have named the major north-northeastward trending fault zone which marks the western boundary of the East Continent Gravity High (Grenville Front of Likiak and Zietz, 1976), the Lexington Fault Zone. This fault zone, which is related to an older featt:re than the Rome Trough, should be considered a separare entity from the Kentucky River Fault Zone. The data of Black et al.,
(1976) strongly indicate that there is no westward extension of the Kentucky River Fault Zone beyond the Lexington Fault Zone "Sich delineates the western boundary of the Rome Trough (Middle Car ian in age) in this area."
2.
Perry Nuc1 car Power Plant FSAR, Page 2.5-14:
'"The Cincinnati Arch is partially controlled by a basement ridge along the Grenville Front."
3 3.
Perry Nuclear Power Plant FSAR, Page 2.5-15:
"The structures along the various arches also exhibit local variations. Tobin (1961), Mayhew (1969), Lidiak and Zietz (1976),
and Ammerman and Keller (1978) have described north trending faults in the surface and subsurface along the east flank of the Cincinnari Arch. On the other hand, it has been indicated that the Bowling Green fault of northwestern Ohio occurs along the western flank of the Findlay Arch (Quick et al.,
1978). Hewever, all of the above authors agree that the faulting noted a'.ong the Cincinnati and Findlay Arches is basement-controlled and reflective of reactivation of Precambrian structures possibly related to the Grenville Front."
4.
" Faults Along the East Flank of the Cincinnati Arch Tobin (1961) and Mayhew (1969) postulate the existence of north trending normal faults in the subsurface of vest-central Ohio, about 175 miles southwest of the Perry site. These faults are reported to be due to possible Paleozoic reactivation of Precambrian structures along the boundary between Grenvil.lian age metamorphosed rocks on the east and older Central Province, unmetamorphosed Precambrian rocks on the west (Rodman et al., 1965)."
III. It is dif ficult to conceive that the above referenced citations and those noted below are not convincing geologic and seismologic evidence that the Grenville Front is a fundamental boundary.
1.
Atherton, 1971:
"The western boundary of the Grenville Province in Canada is a metamorphic front, in places marked by faults.
In Ohio, this boundary, which runs in a southerly direction from near Sandusky, probably marks a major structural boundsry since it cointides with a break in slope in the Precambrian curface. Gravity centours, age data and surface evidence also support such an interpretation (Summerson, 1962)."
2.
Muehlberger et al.,1967:
"A major geological, geophysical and age boundary extends south through central Ohio. The writers believe that this is the subsurface extension of the Grenville boundary."
3.
Ammerman and Keller, 1978 state further that:
"The East Continent Gravity High was described by Keller et al.
(1975) as a Keweenawan age, basalt filled rift which extends through Tennessee, Kent ucky, and possibly Ohio. Lidiak and Zietz, 1976 interprec this gravity high as the signature of the Grenville Front."
4.
Perry Nuclear Power Plant FSAR, Page 2.5-12:
"The Grenville front where it is exposed in Canada is a tectonic break defined from place to place by faults, mylonites, or broad metamorphic transition zones."
5.
Perry Nuclear P>wer Plant FSAR, Page 2.5-13:
" Bayley and Muehlberger (1968) defined the subsurface location of the Grenville Front from southern Ontario through eastern Michigan and western Ohio to northern Kentucky (as shown on Figure 2.5-8), and further described the different lithologies on each side of the boundary. Based on petrographic and radiometric studies of basement well samples, Ammerman and Keller (1976) located the Grenville Front in northern Kentucky between little-metamorphosed igneous re eks to the west, and marble and upper-amphibolite grade, metamorphic rocks (913 and 894 million years, K-AR ages) to the east."
6.
Perry Nuclear Power Plant FSAR, Page 2.5-27:
"They (Burke and Dewey, 1973) suggest that a Grenville Ocean opened on a Keweenawan rif t along the present trend of the Grenville
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Front in east central United States, and upon subsequent Grenvillian plate convergence th: continental crust to the east wrs thickened and the Grenville Front tectonic boundary formed during Grenvillian reactivation about 950 million years ago."
7.
Perry Nuclear Power Plant FSAR, Page 2.5-29:
"The western boundary of the Eastern Stable Platform, the Grenville Front, as drawn on Figure 2.5-13, honors all data f rom wells w'.th i
two exceptien3. Both exceptions are south of Anna, Ohio, where gravitational features are very well. defined. The eastern boundery f
of the Eastern Stable Platform, drawn chiefly on the basis of mapped geological structure, is confirmed by gravity contours."
i The above citations indicate that the Grenville Front has been reactivated since the Precambrian and is a fundamental boundary.
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230.7 In the FSAR, there is no discussion of seismic reflection data in the vicinity of the site. A USGS eeport, entitled
" Lake Erie geological and geophysical data sources" by Hutchinson and Wold (1979), shows some reflection lines in the vicinity of the site. Present and discuss the lines relevant to the site. Also, search the literature or other potential sources for any other reflection data which may exist in the vicinity of the plant.
If the data erist present and discuss the results of your interpretation.
Response
i A review has been made of the available published and unpublished, seismic resolution data in the vicinity of the Perry site, including those data cited by Hutchinson and Wold (1979).
The resolution of the seismic reflection surveys are discussed in the studies.
t Williams, 1978, 1979 (cited in Hutchinson and Wold, 1979), with regard to the high resolution seismic reflection survey performed by. the U.S. Army Coastal j
Engineering Research Center, states ".
. in the vicinity of the Perry Power
]
Plant. The records don't exhibit enough subbottom penetratian into the shale bedrock to expose fault features, but I don't see abrupt changes in the lake floor or acoustic contrasts of sediments to suggest that faults are present."
Wall, 1965, 1968 (cited in Huteninson and Wold, 1979), with regard to the
- ion ir 1960, states on reflection seismic survey carried out under hi 4.
page 3 of Wall, 1965 that (1) "The subbottom souncing system as it was set up and operated on ship was adversely affected by the shallow depth of the lake. The fact that the water depth, which did not exceed 100 feet, was close to the " thumper" hydrophone separation led to a nonlinear printout of the PDR (precision depth recorder). In addition, the use of a PDR I
(precision depth recorder) with a scale range of 2,400 fee; resulted in all the data being compressed into the top 2 or 3 inches of the record thus making it difficult to sort out and read accurately." Wall goes on to state 4
on page 92 of Wall,1968, that " discrepancies in depths to these reflections (Wall is describing several subbottom reflectors he noted) at the intersections (cf track lines) were generally less than 6 feet."
4
Morgan's, 1964 (cited in Hutchinson and Wold, 1979) survey consisted only of fathometer data and as a result did not have the capability to penetrate either the unconsolidated sediments on the Lake Erie bottom or the bedrock beneath. The shallow reflection data, on the bases of their penetration, cannot be used to define rock structures.
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