ML18037A290
| ML18037A290 | |
| Person / Time | |
|---|---|
| Site: | Nine Mile Point  |
| Issue date: | 10/03/1980 |
| From: | Rhode G NIAGARA MOHAWK POWER CORP. |
| To: | Youngblood B Office of Nuclear Reactor Regulation |
| References | |
| NUDOCS 8010070460 | |
| Download: ML18037A290 (106) | |
Text
- 4 V kfASA.RA
" 4 PA'QhAKK NIAGARAMOHAWKPOWER CORPORATION/300 ERIE BOULEVARDWEST. SYRACUSE, N.Y. 13202/TELEPHONE (315) 474-1511 October 3, 1980 Mr. B. J.
Youngblood, Chief Licensing Branch No. 1, Division of Licensing Office of Nuclear Reactor Regulation U. S. Nuclear Regulatory Commission Washington, D.
C.
20555
Dear Mr. Youngblood:
Re: Nine Mile Point Unit 2 Docket'o.
50-410 Your letter of July 9, 1980 requested additional information regarding geology at Nine Mile Point Unit 2.
Enclosed are Niagara Mohawk's responses to questions Q361.26 through Q361.35 contained in the enclosure to your letter.
Very truly yours, NIAGARA MOHAWK POWER CO RATION
/g n
4c Gerald K.
R ode Vice Presid nt System Project Ma agement PEF:ja Enclosures (25) pock
(/~<
8 020GVII$/0
Q361.26 In'our report entitled "Nine Mile Point Nuclear Station, Unit 2, Geologic Investigation,"
(Vol. 1, Section 4.7, paragraph 1), you state that the intensity of the shearing on the cooling tower fault does not appear to diminish toward the known extremities.
However, it is not clear from your report where the southeastern extremity of this fault is and where either extremity of the drainage ditch fault is.
Accordingly, provide data which will indicate the length of the cooling tower and drainage ditch faults and show their relationship, or lack of relationship, to each other.
In your response, consider acquiring this information by running a detailed ground magnetic survey using a field magnetometer (e.g.,
a proton precession magnetometer)
This approach could be followed by trenching, if necessary.
If you choose to respond without doing a field survey using a magnetometer, indi-cate your reasons.
RESPONSE
Figure 361.26-1 summarizes all known observations relevant to the evaluation of the lateral extent of Cooling Tower and Drainage Ditch faults.
The apparent west-northwest terminations of both faults are shown on Figure 361.26-1 as locations Ql and Q2.
Location is considered to be the western extremity of the Cooling Tower Fault because trenches 1 and 2 revealed no evidence" of faulting.
These trenches were excavated 700 feet and 1750 feet west of the cooling tower piping trench.
Location is considered to be the western termi-nation of the Drainage Ditch Fault because the lake water tunnels for Nine Mile Point, Unit II did not encounter the fault.
The east,-southeast extremity of the Drainage Ditch Fault has been determined during investigations of the "compression buckle" disclosed during bedrock excavation for the James A. Fitzpatrick Nuclear Power Plant.
The report entitled, "Fault Study for James A. FitzPatrick Nuclear Power Plant" submitted as a supplement to the James A.
FitzPatrick PSAR provided the following information concerning the extent of the feature:
"Examination of aerial photographs showed a lineation crossing the plant area and corresponding to the projected trace of the fracture.
This lineation was defined in some places by vegetation, probably because the fracture zone served to transmit water.
In other places it was defined by a very slight depression probably due to some
.slight migration of soil downwards into the open jointing.
This feature could be followed on the photographs approximately 6000 feet to the east of the plant site, at which point the lineation became indistinct
Iffy I
lj
Q361.26 Continued and could no longer be seen.
A test pit, No. 7, dug across the location of the lineation at this point showed only flat-lying beds with no evidence of disturbance.
Refraction seismic surveys were able to define the trace clearly in the vicinity of the plant and to a distance of 2050 feet to the east.
Beyond this point, the velocity decay by which the trace was identified was no longer evident.
Several test pits were opened along this trace at locations shown on Figure 1.
Near the plant the fracture zone was readily identified.
Test Pit 5, (Ref. Figure 1) opened at, the limit to which it could be traced by geophysical
- methods, revealed a fracture about 3 inches wide, containing shattered rock, but no gouge.
The rock adjacent to the fracture or joint was closely jointed but did not exhibit the characteristic up-warp associated with the fracture in the station area.
Test Pit 6, about 60 feet east of Test Pit 5, showed only intact rock with moderately closely spaced jointing.
The evidence from these test pits indicates that between the plant and Test Pit 5
the buckling dies and the fracture resolves into a local system of close jointing.
Xn a westerly direction, the trace was followed to within 90 feet of the shore of Lake Ontario, at which point: it is obscured by artifical land-fill for a parking area on adjoining property."
On the basis of the above information it appears that it is appropriate to assume that the east-southeast extremity of the fault 'is somewhere around location Q3 on H.gure 361.26-1.
1 The minimum lateral extent of the Cooling Tower Fault as determined by our investigation is approximately 3000 feet.
As shown on Figure 361. 26-1, this corresponds to the distance between Pit 1 and the overcoring Borehole OC-2.
With the data presently available, it is difficult to place the east-southeast extremity of the fault.
However, the Cooling Tower Fault in terms of the magnitude of displace-ment and degree of cataclasis appears to be very similar to the Drainage Ditch Fault.
Hence, it is difficult to envision the later'al extent of the fault as being signifi-cantlv different, than the length of its analog.
This suggests that the Cooling Tower Fault does not extend beyond location @on Figure 361.26-1.
Q361.26 Continued Investigating the length of the Cooling Tower Fault ana Drainage Ditch Fault by proton magnetometer survey had been considered.
However, the nature of the faulting at Nine Mile Point does not lend itself to detection by this method.
The displacement on the Cooling Tower Fault is small (5 feet of vertical offset at the bedrock surface diminishing to approximately 6 inches at a depth of 200 feet; and 3 feet, of strike slip offset).
Ad-ditionally, it is not believed that the fault extends to the basement.
Consequently, the faulting does not bring rocks with highly contrasting properties in contact with each other and should not offer a distinct magnetic contrast or pattern by which the fault can be traced.
To illustate this, proton magnetometer surveys were con-ducted across the Cooling Tower Fault and Drainage Ditch Fault (Figure 361.26-1).
As shown on the magnetometer profiles (Figure 361.26-2) no pronounced gradients are apparent that would suggest the location of the fault at the surface or at a hypoth'etical projection to the basement.
Examination of the Drainage Ditch Fault, undertaken during the 1977-1978 investigations for Nine Mile Point, Unit II, revealed that the structural development of the fault is essentially identical and contemporaneous with the development of the Cooling Tower Fault.
This structural development has been summarized. in the 1978 report as follows:
"The study revealed that the fault (Cooling Tower) was initially developed as a vertical, left-lateral, strike-slip fault with 2 to 3
feet of stratigraphic displacement.
The fracturing occurred selectively in the strongest rocks of the stratigraphic section, namely the massive part of the Oswego Sandstone.
In
- contrast, the strike-slip fault zone did not develop within the softer rocks of the Transition Zone, and the underlying Lorraine Group.
During the deformation, the fault zone was mineralized by calcite and sulfides.
Analysis of fluid inclusions from this calcite indicates crystallization temperatures ranging from 170 C to 120 C (corresponding to a depth of burial of 3 to 3.5 kilometers)
- Moreover, fluid inclusions in quartz of the host rock indicated that the temperature reached during diagenesis was approximately 170 C.
From these data, it. is interpreted that the fault was formed at the end of the Paleozoic
- Era, during the initial stage of regional uplift,
~gr.,
4
Q361.26 Continued soon after the rocks reached a maximum depth of burial of approximately 3.5 kilometers (km).
At a later time, during the second episode of deformation, the fault plane was propagated downward as a normal fault through the Transition Zone and the Lorraine Group, with a northward dip of 55 to 65 The displacement along this structure was small, not exceeding a few feet.
At this time, the fault zone was also mineralized with calcite and sulfides.
Fluid inclusions in the calcite yielded temperatures of homogenization ranging from 116 C to 73 C
(corresponding to a depth of burial of approxi-mately 2 to 3 kilometers)
The age of the normal fault movement is interpreted to be Late Jurassic to Late Cretaceous.
The third episode of deformation on the Cooling Tower Fault was characterized by reverse-slip, bedding plane slip, and dilation within 200 feet of the bedrock surface.
Field evidence clearly indicates that there were two phases of movement.
'The first phase preceded the deposition of the overburden sediments, occurring prior to 12,500 years B.P.; whereas, the second phase post-dated the deposition of these sediments.
During the first phase of deformation, dilation of the bedrock strata on the hanging wall of the structure resulted in a reverse strati-graphic displacement that, decreases from 5 or 6 feet near the ground surface to zero at a depth of 200 feet.
This deformation is attributed to a mechanism of buckling, and is believed to have been initiated during crustal downwarping induced by glacial loading.
The deformation during the second phase is expressed as two types of structures:
l.
fluidized flow structures in the over-burden sediments, and; 2.
folds and faults which deform the fluidi-zation structures.
This phase of deformation is attributed to a mechanism of bedding plane slip which probably was caused by changes of fluid pressure in the
l
Q361.26 Continued bedrock associated with water level fluctuation in the Ontario Basin during the draining of glacial Lake Iroquois."
The identical structural character of both faults, coupled with their contemporaneous development, indicates that they are related to each other.
Furthermore, both of these faults must be a part of an integrated deformational system which. is linked to a common tectonic source and/or tectonic event(s)
The April 1978 report linked the development of the faults with the tectonic development of the region.
At that time knowledge concerning local geologic structure was more limited than at present.
This knowledge was substantially enhanced as a result of geologic studies performed at the New Haven Site.
Reference should be made to Figures 2.5-9 and 2.5-15 of the New York State Electric 6 Gas Preliminary Safety Analysis Report for New Haven Units 1 and 2.
These figures present certain aspects of the local tectonic settinq which are important in understanding the relationship among faults and possible linkage to a common tectonic source.
It appears that the development of the Demster Structural Zone was accompanied by gentle warping of the sedimentary strata on either side of the zone.
Particularly important is the occurrence, in the vicinity of t:he Nine Mile Point Site, of a broad syncline.
As shown on New York State Electric 6 Gas Figure 2.5-9 the axis of this syncline trends north-northeast and its projec-tion is located just east of the James A. Fitz'patrick facility. Figure 361.26-1 presents a spatial relation-ship between the Cooling Tower and Drainage Ditch faults and the axis of the syncline.
The axis appears to be situated half-way between the previously interpreted extremities of both faults.
This suggests that there may be a causative relationship between the syncline and both the faults as indicated on Figure 361.26-3.
It should be recognized that the relationship, as noted
- above, would account for the remarkable change in the character of deformation, that is, from strike-slip to normal.
This change could be attributed to a local clockwise rotation of the trajectory of greatest prin-cipal stress in response to continued shortening.
Once this trajectory assumed a position close to the pre-viously formed left lateral shear fracture then conditions.
were favorable for development of normal faulting along this fracture.
Q361.26 Continued REFERENCES New York State Electric
& Gas Corportation,
- 1979, New Haven Units 1 and 2, Preliminary Safety Analysis Report, Docket No.
STN50-596 and STN50-597.
Niagara Mohawk Power Corporation, 1978, Nine Mile Point Nuclear Station, Unit 2, Geologic Investigation,
- Scriba, New York.
Power Authority of the State of New York, 1967, Fault Study for James A. Fitzpatrick Nuclear Power Plant, Appendix "F" Supplement to Preliminary Safety Analysis Report.
L A JI'Z NINE MILE POINT NUCLEAR QENERATINQ STATON TRKNCH I RAOWASTE FAULT UNIT I UNIT 2 TITENCH 2
..OI
~IT I
-E X
/
J' I
I I
I ONT A8/0 II/
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//
I COOLING WATER SITAXE SHAFt I
~aaEEssc 4Tcs Il TCITvEEC I
///
I I
~TTAXK ANO OISCHARGE TUNNELS SARGE SLIP 70'TS TEPEE FOLD Wif OS JAMES A. FITZPATRICK NUCLEAR POWER IR.ANT
/
/ /
~0 ~ SS ~ NORMAL FAULT
//
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PLANT NORTH
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C00 000 sto Co FCCT IXXX.INO TOWER KXCAYATION MAGNETOMETER SURVEY LIKE 2 COOLINQ TOWER FAULT TRENCH I
/
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IIAGNETOMETER SURVEY STATION TRENCH S
OC 2 I
jN ii MAGNETOMETER SURVEY LIKE I
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0 x+
EXPLANATION:
TIILOE Of IIOO O
OTEEOLT TO IIOOERLTELT OIOOIOO TTIIOOTORE SITE LOCATKN SHOWINS LOCATIONS Of IQIOWN WN W TIRNMH STNICTlSEO RELATED TRENCHES AND EXCAVATIONS
"..ff'RKHCH KXCAYATEO TO INVESTISA'fK THK COOLIHO TOWER FAULT C9 e References Position of Inferred Syncline fran N.T.S.
Electric and Cas Corp.,
- 1979, Nev Haven Units 1 and 2 PEAR, AsendEEEent 1, PiO. 2.5-9.
NINE MILE POINT NUCLEAR STATION UNIT 2
NIAQARA MOHAWK POWER CORP.
FIGURE 561.26 - I
1!
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SgEG S.S.
SROVP LORRAINE
. >eg"'4q e p.
9 g]
<cg4l)g ~
Cg~es gO l
I Sense of Shear Strain induced by shortening along Demster Zone REPRESENTATION OF INITIALFOLDING AND
,RESULTING SHEAR AND EXTENSIONAL FRACTURES REPRESENTATION OF ROTATION OF PRINCIPAL STRESSES.
SUCH THAT, EXTENSION IS PARALLEL TO ORIGINAL WNW TRENDING SHEAR FRACTURE RESULTING IN DIP SLIP
'" DISPLACEMENTS ON DISCONTINUITIES OF SIMILAR TREND DIAGRAM OF-FOLD / FAULT RELATIONSHIPS NINE MIL'E POINT NUCLEAR STATION UNIT 2
NIAGARA MOHAWK POWER CORP.
FIGURE 361.26 3
Q361.27:
Indicate spatial and age relationships of the faults at Nine Mile Point, to the geologic structures at the site proposed for the New Haven facility and to other geologic structures in the region.
Furnish a map and the necessary data to support your conclusions.
RESPONSE
In the region immediately around the Nine Mile Point Site (30 mile radius) there is only one structure known.
This structure, located near New Haven, New York is known as the Demster Structural Zone.
Figure 361.27-1 is a map showing the spatial relationship of the faults at Nine Mile Point to the Demster Structural Zone.
Presently, there are no data available from either site which would permit a direct, absolute determination of the age of development of structures at each siie.
Nevertheless, the existing data base permits a reasonable interpretation of the age relationship of the high angle faults at Nine Mile Point to the Demster Structural Zone.
This interpretation is based upon" results of fluid inclusion studies.
These studies were performed independently at each site and are sufficiently broad in scope to warrant a meaningful com-parison.
Clearly, the faults at each site are mineralized, and the mineral assemblages are similar.
Furthermore, at both sites the mineral assemblages yielded identical spectre of homogenization temperatures.
Table 361.27-1 and Figure361.27-2 present the results of fluid inclusion studies at both sites.
It appears that at each site the minerals occurring within fault zones precipitated from fluids.whose temperatures
.range from 170 C to 80 C.
Based on this, it can be inferred that the development of the faults at Nine Mile Point (strike-slip and normal faulting) and movements along the Demster Structural Zone occurred under similar depths of burial (depth of burial ranging from approximately 3 kilometers to 2 kilometers) that is, in correlative geologic times.
This conclusion is supported by movement plans (left-lateral) and the geometric arrangement of faults at Nine Mile Point relative to the trend of the Demster Structural Zone.
The high angle faults at Nine Mile Point may be regarded as members of a systematic fracture set identified onsite.
This frac-ture set consists of two conjugate strike-slip shear frac-tures trending west-northwest (left lateral) and northeast (right lateral).
The trend of the acute bisectrix of the set indicates the direction of structural shortening re-quired to produce the fractures in their present arrange-ment. It can be seen from Figure 361.27-1 that the direction of shortening indicated by the Demster Structural Zone is close to the trend of the acute bisetrix of fractures at Nine Mile Point.
This coincidence suggests contemporaneous developments at each site and thus reinforces earlier drawn conclusions.
In summary, the presently available data indicate an age and causative relationship between the faults at Nine Mile Point and the geologic structures at New
Q361.27 Continued Haven.
These relationships appear to have been established in the distant geologic past (Late Paleozoic-Early Mesozoic).
As noted previously (response Q361.14),
evidence of Late Cenozoic bed-rock displacement has only been encountered at Nine Mile Point.
0
TABLE 36l.27-1 sAvpLE /t Tl I 21A TII 42
'TII 19 TII 39 TII 7 TII 25 38 157.2 35a l49.4 37 138.8*
40 137.8 36a 121.7 35b 103.1 36b 101.0 35c 99.2 33 98.3 24a l57.9 3la 155.4 24b 154.3 23a 141.8 3lc 138.3 3lf 137.8 31e 129.1 31d 124.3 Xnclusion¹ T C Inclusion¹ T'C 18b 159.9 15 158.3*
16 147.8 10 128.3 22b 127.2*
18a 124.6 21 124.6 22a*ll4.2*
55 179.6 59 163.8 56 155.6 S4 150.4 61c 135.2 50, 132.5 61b 116.2 44 148. 5 43 144.6 4S'28.8*
46a 118.9 49 93.1 46b 92.0 42 75.7*
Inclusiong T'C Inclusiong T'C Inclusion¹ T'C Inclusion¹ T"C 6
170.4 6b 170.4 5b 155.1 9b 152.5 5a 152.0 1
12S.2 4
122.5 Mean Std.
Dev.
122.9'C 23.4 142.4 C
12.5 135.6'C 17.2 147
~ 6 C
21.3 114. O'C 28.1 149. 7'C 19.3 Refer..
Reference:
- Xnclusions found in milk areas.
New York State Electric
& Gas,
- 1978, Preliminary Safety Analysis Report,,
New Haven Units 1 and 2, Amendment 1, Table l.
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I000 2000 NINE MILE NIAGARA POINT NUCLEAR STATION UNIT 2
MOHAWK POWER CORP.
FIGURE 361.27 - I
80 90 100 TEMPERATURE (DEGREES CENTIGRADE) 110 120 130 140 150 160 170 PRI NARY INCLUS IONS HOST ROCK
~
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SECONDARY INCLUSIONS
.w BL8kA 0!IIh~a FLUID INCLUSION TEMPERATURE DISTRIBUTION
Q361.28 Indicate the relationship among the thrust faults, the cooling tour fault, and the drainage ditch fault.
Specifically, indicate whether they connect as an inte-grated system and whether the thrust faults cut the the other faults.
RESPONSE
Thus far, no direct geologic evidence has been identified relevant to an unambiguous definition of age and spatial relationships among the "thrust" faults, the Cooling Tower Fault and the Drainage Ditch Fault.
Presently, there are only a few exposures of the "thrust" faults known at the site.
These are:
the North Radwaste
- Trench, the Cooling Water Intake Shaft, Lake Water Tunnels and the Circulating Water Piping Trench.
Figure 361.28-1 presents the location of all "thrust" structures known at, the site. It can be noted that these structures were recognized only within a bedrock block bounded by the hiqh anqle faults.
There is no single exposure wherein both types of structures are present.
Furthermore, the absolute age of formation of the "thrust" faults, as well as their relative age with respect to the reverse slip deformation observed on the Cooling Tower Fault, cannot be determined with certainty.
Consequently, the possible age and spatial relationships are inferred from the existing data base.
The "thrust" fault structures appear to have been formed as a result of relief of strain energy stored in the bedrock.
The strain energy is inferred to be of remanent gravi-tational and/or tectonic origin.
As such, in the time scale of concern and in the tectonic environment of the site region, the energy once relieved or reduced cannot be replenished.
That is, it is only conceivable that either no change or a decrease in the amount of stored strain energy occurs after the initial movement has taken place.
The development of the "thrust fault" structures must have been triggered (initiated) by some environmental change (for example, glaciation) which reduced the ability of the bedrock to retain the strain energy being stored at the time such a change occurred.
The ability of a given block of bedrock to retain a
given amount of strain energy is governed by the shear resistance of block boundaries and the lateral restraining forces.
A reduction of one of these factors results in a reduction of the integrated restraining force and must be followed by a reduction of strain energy stored within the block.
The latter reduction will be expressed on a lengthening of the block accompanied by the developm'ent of nonhomogeneous shear strains along the boundaries.
The process, if continuous,
Q361.28 Continued may be characterized as "leakage" of the strain energy induced by the reduction of the capability of the block to retain the stored strain energy.
Presently, there is no known direct geologic data per-mitting a firm definition of boundary conditions of the bedrock-block whose lengthening is evident in the ex-posures of the "thrust" faults.
However, with the information presently available, it is possible to postulate reasonable boundary conditions as presented on Figure 361.28-2.
Once these boundary conditions are assumed then it is possible to perceive the nature of the environmental change which permitted the develop-ment of the instability.
With reference to the "thrust" fault structures, the factors which controlled the initial strain energy stored in the bedrock may be identified as:
1) the lateral restraining force provided by the bedrock which has been removed by erosion during the formation of the north-south trending erosional valley located between Nine Mile Point Units I and II (Figure 361.28-1);
2) the shear resistance of the boundaries of the block consisting of following elements (Figure 361.28-2):
a) shear resistance along boundary 1
dSl Cl + t
~l
~
2')
shear resistance along boundary 2
dS2 C2
+
an ~2 dd n2')
shear resistance along boundary 3
dS3=
C3 + tan p3
. d~nl.
In the instance of the shear resistance of this boundary the shear stress acting along bedding planes
(< bed) should be accounted for and thus, dS3=
(C3 + tan p3
. dd nl)
+
bed.
As indicated by the above equations the combined shear resistance of the block boundaries is controlled by the bedrock mass properties (C=cohesion and P=angle of sliding friction), the normal stress perpendicular to the block boundaries (0 nl and 0 nq),
and the shear stress acting along the plane of bedding (g bed).
Q36l.28 Continued The latter two factors must have experienced significant changes in response to gravitational loading of the litho-sphere by the continental ice sheet(s)
Other related phenomena were also important.
They include changes of water level in the lake (fluid pressure and reduction oft'l) and shear straining of the lithosphere caused by glacially induced differential vertical movements (tilting during downwarping and tilting during rebound)
Considering the foregoing, the following scenerio of development of the "thrust fault structures can be outlined:
(i)
Downwarping of the crust. in relation to glacial advance created conditions favorable for buckling of the hanging wall blocks of northward dipping high-angle faults.
This resulted in a reduction of~2 and hence reduction of dSl and dS2,.
(ii) erosional formation of the valley reduced lateral restraining force, and; (iii) removal of the load imposed by the continental ice sheetreduced 0 n
- and, thus reduced dS3.
Fuither reduction ok nj, and dS3 may have occurred during the drainage of Lake Iroquois (development of high fluid pressure in-the bedrock)
In summary, the present understanding of the site conditions strongly suggests that. the "thrust faults do not cut the Cooling Tower and Drainage Ditch faults.
It appears that the "thrust" faults together with the high angle faults form an integrated, but sequential system of bedrock deformation.
The present under-standing of the equilibrium conditions of the thrust structures implies that the development of buckling (Phase I of the reverse slip deformation) along the Cooling Tower and Drainage Ditch faults contributed to the instability of the bedrock block bounded by both faults.
Additionally, it can be inferred that the development of the "thrust faults" post-dates the first phase (response 36l.30) of reverse slip movement along the Cooling Tower Fault.
REFERENCE Niagara Mohawk Power Corporation, 1978, Nine Mile Point Nuclear Station, Unit 2, Geologic Investigation,
- Scriba, New York.
0
INTAKE AND DISCHARGE TUNNELS ON 7 AIIT'/0 NINE MILE POINT NUCLEAR GENERATING STATION VNIT I/
I
/UNIT a O~
/
I RADWASTE FAULT 0w
/
~2'~
1'
~2~~
INTAKE AND DISCHARGE TUNNELS 6o 65m
~ NORMAL FAULT "TEPEE FOLD" a
I COOLING TOWER EXCAVATION 1
t l
JAMES A. FITZPATRICK NUCLEAR POWER PLANT 60 COOLING TOWER FAULT EXPLANATION:
TRACE OF MODERATELY TO STEEPLY DIPPING STRUCTURE
~2'~
BEDROCK SURFACE CONTOUR IEL'N FEETI LOCATIONS OF OBSERVED OCCVRENCES OF STRUCTURES SIMILAR IN CHARACTER TO RADWASTE STRUCTURE 0
400 800 SCALE FEET S IT E LOCATION MAP SHOWING GENERAL CONFIGURATION OF BEDROCK SURFACE AND LOCATIONS OF KNOWN GEOLOGIC STRUCTURES NINE MILE POINT - NUCLEAR STATION UNIT 2
NIAGARA MOHAWK POWER CORP.
FIGURE 361.28-1
Drainaae Ditch Fault Bounda ry Ql
~ Strain
~ restq Cooling Tower Fault Boundary Q2 PLAN unconso idated Late sediments
~
~
~
~
~
~
~
~
~
~
Land Surface Wisconsin to Early Holocene.
W
'.P
~Stra in Oswego Sandstone Unit A of Pu laski bed SECTION A AI estd Boundary Q3
~
~
~"
~n 2
~
Land Surface
~ Top of Bedrock
.. -Oswego Sandstone Pulaski k
Depth of instability Drainage Ditch Fault Cooling Tower Faui, POSTUI ATED BOUNDARY
.COMDITlONS SECTION 8 B' NINE MILE POINT NUCLEAR STATION UNIT 2
NIAGARA MOHAWK POWER CORP.
FIGURE361
~ 28-,2
0
Q361.29:
Extend coverage of the lineament map (Volume II, Plate l-l) out to a radius of at least 5 miles.
Field check the lineaments to determine if they are reflections of unrecognized geologic structures.
RESPONSE
Figure 361.29-1 is a map of air photo lineaments identified within a 5 mile radius of Nine Mile Point Nuclear Station, Unit.II.
The air photo lineaments were identified by tonal variations on low altitude aerial photographs (approximate scale 1:20,000) flown in 1938 and 1939.
No ghoto lineaments.could be identified in many areas, including the area of the James A. FitzPatrick Nuclear Power Plant, because these areas were heavily forested.
The lineaments were mapped on mylar overlays to the aerial photographs and then transferred to a 1:24,000 topographic base map.
The lineaments were then checked in the field to determine whether or not they reflect unrecognized geologic structures.
II Within the 5 mile radius, the majority of the bedrock surface is veneered with Late Wisconsinan and Holocene deposits.
The surface topography reflects landforms related to Late Wisconsinan Ice.
To the south of Nine Mile Point, long, parallel ellipitical hills or drumlins oriented approximately N20 W are the dominant topographic 0
feature.
The topography of the drumlins and inter-drumlin areas has been modified by erosion and deposition as evidenced by occasional knobs and ridges subparallel to the Late Wisconsinan ice margin.
Further topographic modification occurred during Lake Iroquois and other pre-Lake Ontario lake stages as evidenced by lacustrine deposition and erosion, and weakly define fluvial terraces.
In general, the. lineaments identified within the 5 mile radius may be related to the following non-cultural con-ditions:
- 1) surface topography such as streams and ridges not related to bedrock conditions,
- 2) surface topography related to discontinuities in the bedrock
- 3) joint or fracture patterns in the bedrock,
- 4) structural discon-tinuities such as folds or faults, and;
- 5) topographic variations on the bedrock surface produced by preferential glacial plucking.
Several lineaments identified on the lineament map can be related to previously identified geologic structure.
A series of N40E to N45E trending lineaments were noted from east of Hammonds Corner to Demster-Beach (Fig-ure 361.29-1).
These lineaments are coincident with the Demster Structural Zone and associated folds as mapped by Weston Geophysical, 1978.
Location Ql on Figure 361.29-1 shows three parallel N45 E-trending>
linear, dark photo tones less than 1000 feet long.
Q361.29 Continued Although there are no bedrock outcrops in the vicinity of these lineaments, trenching completed by Weston Geo-physical in 1978 verified the existence of the Demster Structural Zone at this location (Figure 361.27-1).
Several N40 E trending air photo lineaments were iden-tified parallel to and north of and coincident with the axis of the Demster Beach anticline.
The extent of N40 E
to N45 E trending lineaments appears to be limited to 0
the Demster Structural Zone as few N40 E to N45 E linea-ments were identified to the west of the known extent of this zone.
LocationQ2 (Figure 361.29-1) is a lineament nearly coincident with the Cooling Tower Fault.
- However, this area is now covered with filland the natural surface conditions could not be field checked.
This lineament is expressed on air photos as a linear, relatively dark photo tone, approximately 50 to 75 feet wide and 3000 feet long.
The lineament appears not to be related to surface topography, as it crosses topographic highs and lows.
It is not observed to extend toward the southeast beyond trench 5 and it only is noted to extend a few hundred feet northwest of pit 1 (Figure 361.26-1)
The lineaments south of the main east-west road (Lake Road) and east of trench 5 (Figure 361.29-1) are related to topographic lows.
No bedrock outcrops or anomalous surface conditions were found in this area.
The same is true for the short linea-ment about 500 feet southwest of trench 5.
At location on Figure 361.29-1, Unit 1, three west-northwest trending en echelon lineaments are connected by two north trending lineaments.
This system appears to represent bedrock topographic variations because several bedrock outcrops were observed along the trace of these lineaments.
No bedrock outcrops were found in the immediate area away from the lineaments.
The glacial drift is apparently thinner along the trace of the linea-ments.
In general, the lineaments appear to be associated with a topographic high.
However, the relationship is not consistent as some of the lineament segments cross topo-graphic lows.
The surficial evidence is not sufficient to determine if this lineament system represents struc-tural discontinuities, joints, or bedrock topography produced by preferential glacial plucking.
The lineaments (Figure 361.29-1) south of the above dis-cussed en echelon lineament system represent air photo tonal variations that cross topography.
No bedrock outcrops or anomalous su~face conditions could be found in this area.
At location@,
a lineament approximately 1500 feet long and 100 feet wide, relatively dark, photo tone trends approximately N30 E and is located east and subparallel to the Heater Bay Structure.
This area is excavated and the natural surface conditions could not be checked in the field.
Q361.29 Continued At Sunset Bay (location Q5, Figure 361.39-1) two lineaments were noted; one trending N60oE approximately 3500 feet long cutting across topography as a relatively dark photo tone and the second trending N45oW in part parallel to a small unnamed stream.
No rock outcrops were located in the vicinitv of these lineaments
- and, dense forest plus fillat the James A. FitzPatrick Nuclear Power Plant Site prohibit checking the natural topography in this area.
Surficial evidence is insufficient to determine whether these lineaments reflect structural discontinuities, joints, or bedrock topography produced by glacial plucking.
A distinct N20 W lineament trend was mapped.
These lineaments are coincident with surface topography, such as drainages and,ridges in the form of elongate drumlins.
These lineaments are also coincident with the direction of Late Wisconsinan ice flow out of the Ontario Basin toward the southeast and do not reflect unrecognized geologic structure;
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NIAGARA MOHAWK POWER CORP.
FIGURE 36I.29 - I
0361.30 Furnish additional discussion and documentation to support your conclusion that post-glacial reverse movement did not occur below 200 feet on the cooling tower fault., Our concern in this matter is that if this fault had previous normal movement as you suggest, and if the displacement on this fault is presently zero at the 200 foot depth, then it appears that reverse movement must have occurred below the 200 foot level to bring the net displacement to zero.
RESPONSE
All available documentation and discussions supporting the conclusion that "post-glacial reverse movement did not occur below 200 feet on the Cooling Tower Fault" have been presented in the April 1978 report.
Development of additional documentation through subsurface exploration is considered to be unwarranted.
By way of summary, some of the relevant arguments are given below.
The main conclusion of the April 1978 report was that the latest movements observed along the Cooling Tower Fault correspond to buckling of the near surface bed-rock strata forming the hanging wall block of an old normal fault.
This buckling, termed in our report the "reverse slip deformation",
should be distinguished from "reverse movement".
The reverse slip deformation occurred 3.n two phases.
The initial or the main phase corresponds to the development of buckling down to a depth of approximately 200 feet.
This phase of deformation occurred "prior to the Wisconsinan glaciation and the deposition of overburden sediments,"
(that is, prior to "postglacia' time).
The second phase of deformation has been recognized only in the near-surface bedrock strata and overburden sediments.
It is not known whether defor-mation related to this phase extends all the way down to a depth of 200 feet.
The age of this second phase of deformation is Holocene, (that is, "postglacial" )..
The data base relevant to interpretation of the depth of development of the reverse slip movements consists of:
(i) stratigraphic correlations across the Cooling Tower Fault; (ii) relationships between stratigraphic separation and depth, and; (iii) results of detailed examinations of rock cores extracted from the fault zone.
The data clearly indicate that:
(i) the stratigraphic separation resulting from the reverse-slip movements varies in a linear manner with depth.
Figur'es 361.30-1 and 361.30-2 present
Q361.30 Continued the relationship of stratigraphic 'separation and depth.
It can be seen that downward the sepa-ration becomes progressively smaller.
At a depth of approximately 200 feet there is no relative displacement of the strata; (ii) below a depth of approximately 200 feet the sense of fault displacement is nor'mal; and (iii) the occurrence of a deformational fabric attributable to the reverse-slip deformation appears to be restricted to the upper 200 feet of the fault zone.
Combining the above observations, it can be concluded that the stratigraphic separation varies linearly with depth indicating that there must be a limiting depth below which the reverse-slip deformation is not present.
Assuming that the normal fault separation is not large (smaller than 5 feet), it follows that this limiting depth does.not exceed 400 feet.
Additionally, the occurrence of deformation fabric (attributable to the reverse slip deformation),
selectively within the upper 200 feet of the fault zone suggests that the limiting depth does not exceed a value of approximately 200 feet.
Further means of estimating a value of the limiting depth can be obtained from Figure 361.30-3.
Before this can be accomplished the following points should be recognized:
(i) the reverse-slip deformation and/or separation is a result of buckling of strata forming the hanging wall block.
The buckling occurred against the old fault whose inclination is approximately 60 toward the north, that is toward the hanging wall block; the wavelength of each individual buckle is limited by the wavelength of the uppermost buckle (Ll on figure 361. 30-3),
and the inclination of the fault.
(iii) buckles whose wavelength LM0 require layer parallel normal stress gg H~ 'in order to be formed.
This relationship is depicted on Figure 361.30-4.
Considering the above points, it follows from Figure 361.30-3 that the maximum possible depth of occurrence of the re-verse-slip deformation, D
, is less than a value given
Q361.30 Continued by the following equation:
Ll D
tan (90-4 )
where:
4 = inclination of the fault;
=. wavelength of the upper deflections FromPigure 361.30-5 it can be seen that Ll does not exceed a value of 130 feet.
- Hence, D
is equal to approximately 225 feet.
The actual depth of the r
reverse slip deformation must be less than this value.
0
SOUTH SIDE IS UP AIO NORTH SIDE IS UP AHO FNILT slsPUcfNK L mUiT 0ls UcBIE 1 15 IS NORMAL HIGH ANGLE REVERSE STRATIGRAPHIC SEPARATION IN FEET I
2 d
TOP OF CEDRQCK 0
~
s 4
c 0
EXPLANATION <
~ Stratlgrophlc displacement measured odJocont to tha (nuit plane.
o stratlgrophlc displacement measured 20 (aet ovoy (rcm ohe (suit plane.
NOTE:
(I)
Dlsplocements sheen neer top o( the bedrock ora based on observations node In trench (2)
Olsplocements sheen ln unccnsolldatod sodlamnts Includes monocllnol (loxure over the (nuit.
DIAGRAM SHOWING RELATIONSHIP BETWEEN STRATIGRAPHIC DISPLACEMENT AND DEPTH IN BORINGS T I THROUGH T" 5-10 NINE MILE POINT NUCLEAR STATION UNIT 2
NIAGARA MOHAWK POWER CORP.
FIGURE 361. 30-1
SOUTH SIDE IS UP ANO FAUI.T DISPLACEMENT IS NORMAL NORTH SIDE IS UP ANO FAULT DISPLACEMENT IS HIGH ANGLE RETERSE STRATIGRAFHIC SEPARATION IN FEET 2
J d
TOP OF BEDROCK
~
0 0
~
0
~
0
~
0
~
~ f EXPLANATI ON t
~ Stretlpraphlc displacement e>>asured odJacent to tho tault plane.
0 StrotlGraphlc dlsplacenent a>>soured 20 toot arsy tron tho fault plane.
NOT Et Ill Olsplacomonts sheen near top Ot the t>>drock aro based on observations node In trench a,
DIAGRAM SHOWING RELATIONSHIP BETWEEN STRATIGRAPHIC DISPLACEMENT AND DEPTH IN BORINGS T I THROUGH T l2 NINE MILE POINT NUCLEAR STATION UNIT 2
NIAGARA MOHAWK POWER CORP.
FI6URE 361. 30-2
DEPTH 0
FAULT LI 40 L2 2
Dr2 L3 Or>
-l40 4.
L4 Dr4
-200 ASSUMING:
tI= t2=t3=t4; LI > L2 > L) > L)
HENCE:
LI /tI > L~/t2 > LP/tg > Lg/tg Dr4= MAXIMUMPOTENTIAL DEPTH OF REVERSE-SLIP DEFLECTION.
(DEPENDS UPON LI, AND IS CONSTANT FOR A SPECIFIC SYSTEM.)
L =WAVELENGTH OF DEFLECTION Or=DEPTH OF REVERSE-SLIP DEFLECTION t= THICKNESS OF STRATA DEVEL'OPMENT OF MAXIMUM POTENTIAL DEPTH OF REVERSE-SLIP DEFLECTION NINE MILE POINT NUCLEAR STATION UNIT 2
NIAGARA MOHAWK POWER CORP.
FIGURE 361. 30-3
tot
~~xx+<<ix >
SE OEVEI.OPED INCREASE IN STRESS NECESSARY TO REDUCE SLENDERNESS RATIO FROM'/I AT POINT 2 TO L/t AT POINT 3 I
I I
I I
2 STRESS IN THE BEDROCK PRIOR TO FORMATION OF THE X/2 BUCKLES A
b,L/,
RANGE OF SLENDERNESS RATIO OF THE UPPER INITIAL DEFLECTIONS MINIMUM POSSIBLE SLENDERNESS RATIO CORESPONDING TO MAXIMUM POTENTIAL DEPTH OF'THE REVERSE - SLIP DEFLECTIONS RELATIONSHIP OF LAYER--PARALLELSTRESS TO SLENDERNESS RATIO ASSUMED NECESSARY TO CAUSE BUCKLING ON THE COOLING TOWER FAULT NINE MILE POINT NUCLEAR STATION UNIT 2
NIAGARA MOHAWK POWER CORP.
FIGURE 361.30-4
SSW DEPTH 0
o a
o O
o O
th o
0 a
OVERBURDEN o
O
~
a O
25 OSWEGO SANDSTONE 50 75 FULL WAVE (X)
BUCKLE TRANSITION ZONE OF OSWEGO SANDSTONE 100 ZONE OF FLEXURAL SHEAR DISPLACEMENT PULASKI FORHATION 125 150 HALF WAVE (>/2)
BUCKLE 175 ZONE OF DIRECT SHEAR DISPLACEHENT WHETSTONE GULF FORHATION 200 225 250 REVERSE SLIP DISPLACEMENTS DUE TO BUCKLING ON COOLING TOWER FAULT OLD NORHAL FAULT NINE MILE POINT NUCI.EAR STATION UNIT 2
NIAGARA MOHAWK POWER CORP.
FIGURE 361
~ 30-5
Q361.31:
In Section 3.2 of the Executive
- Summary, you conclude that future displacements along the deformation struc-tures at the site will involve vezy low strain rates.
Using the data available for these structures, provide a discussion as to why past Quaternary movements and possible future movements should be classified as slow (i.e., creep) versus rapid (i.e., seismic).
RESPONSE
The amount of seismic energy radiated as a result of slip along a fault in a given bedrock environment is a function of the stress drop and the source dimensions.
Furthermore, for an earthquake to occur (the amount of seismic energy radiated is large) the stress drop must attain a value which is appreciably greater than zero.
Typically, earthquakes are accompanied by stress drops ranging from 50 to 100 bars (approximately 750 pounds per square inch to 1500'ounds per square inch).
Moreover, the earth-quake related reduction of the in situ stress must be accomplished within a very small time interval, say 10 seconds., In other words, the change in stress with re-spect to time must be relativesly large.
In the April 1978 report. it. has been stated that the slip conditions accompanied by large, relatively fast stress changes can be only conceived during the development of the rotated bedrock sliver (see Sections 7.0 and 8.0 Volume I).
Furthermore, it has been demonstrated that it is not possible to form another rotated bedrock sliver below a depth of approximately 160 feet.
From the present understanding of the site conditions and the mechanism of Quaternary deformation, it cannot be ruled out that minor, near-surface adjustments may occur in the future.
These adjustments are considered to be related to:
Further increase in amplitude of individual deflection within the depth interval of.140 to 200 feet, (below the rotated bedrock sliver where the stress drop was relatively small).
The process will be arrested and/or mitigated by the higher deflections whose stress drop was significant.
Development of swelling strains in areas where the earlier deformational processes reduced the con-fining pressure below a given value of the first stress invarient (see response to Q361.34).
It is expected that the occurrence of these strains will be limited to a rock mass above a depth of 160 feet.
(iii)
Viscous "flow" of the bedrock in areas where the stress gradient is sufficiently large.
Q361.31 Continued (iv)
Reduction of the ability of bedrock, surrounding the perturbation, to maintain a given stress gradient.
This reduction is related to the time dependent increase of the water level in the Ontario Basin.
This increase will have a minor negative effect on the shear strength of bedding and thus, may facilitate further reduction of the existing stress gradient.
All the above mentioned processes are related to either rheological properties of the bedrock (viscosity and swell) or to the time dependent environmental changes (pore pressure)
The resulting strains must also be time
'dependent.
The strain rates, associated stress
- drops, as well as the rates of stress drops are infinitestimally small.
The existing stress gradients will be decreasing, resulting in a time dependent reduction'f the strain rates-In summary, following the reasoning presented
- above, as well as that presented in the April 1978 report, it can be concluded that should any future adjustments occur in the vicinity of the Cooling Tower Fault, it is expected that they will involve very limited volumes of the bedrock as well as very low strain rates.
These adjustments are of no consequence in the context of vibratory ground motion.
REFERENCES
- Brune, J.N.,1970, "Tectonic Stress and the Spectra of, Seismic Shear Waves from Earthquakes,"
Journal of Geophysical
- Research, Volume 75, pages 4997-5009.
Niagara Mohawk Power Corporation,
- 1978, Nine Mile Point Nuclear Station, Unit 2, Geologic Investigation,
- Scriba, New York.
Q361.32 Our position regarding the dating of the age of the last movement on the faults based on an apparent temper-ature of mineralization is that this method should be used with caution.
Accordingly, provide your basis for discounting the possibility that frictional heat on the fault planes, generated during deformation, could cause the observed fluid inclusion temperatures.
- Further, indicate your basis for discounting the possibility that, fluids which deposited the calcite were heated above the ambient geothermal gradient.
RESPONSE
We recognize and agree with your position regarding the need for caution when utilizing data from paleogeo-thermometry and paleogeobarometry to interpret the age of latest displacement along a fault.
- Indeed, the data by themselves do not provide direct information per-taining to their time of origin.
- Instead, one must infer this information based upon other data regarding the samples, their origin and local geologic (structural) relationships, and knowledge of the regional tectonic framework.
Where these supplementary data are not available, paleotemperatures can be equivocal.
It was with this potential ambiguity in mind that the fault and fracture fillingminerals were assessed as to their emplacement mechanism, environment and time of origin in the 1978 report (Niagara Mohawk Power Corporation, 1978; Geologic Investigations Nine Mile Point Nuclear Station Unit 2; Volume I).
Since the completion of that report all available fluid inclusion data for northern New York State and southeastern
- Ontario, Canada were reviewed.
Additional=-
data have been obtained from investigations for a Pre-liminary Safety Analysis Report for New Haven which is approximately 5 miles to the southeast of the Nine Mile Point Site.
These newer data were reviewed and assessed in responses to Questions 361.13 and 361.14 which were submitted in June 1980.
Comparison of these results with those reported in Section 2.2.4.2 of the 1978 report reveals that the majority of regional tempera-tures of homogenization are consistently in the range of 65 Centigrade (C) to 178 C.
These values (a) are in excellent agreement with the data from the Nine Mile Point Site, and (b) represent temperatures.
obtained from specimens from a variety of specific settings including joints, beds, and stylolites, as well as faults.
Intuitively, the quantity of frictional heat generated by shearing along these other features in comparison to faults would be minimal.
- Hence, one should be suspicious of the possible explanation that heat from frictional resistance to shear accounts for the high temperatures calculated from fluid inclusions.
Q361.32 Continued There are two lines of evidence indicating that the temperatures of homogenization recorded by the calcite and quartz (in the host rock) represent heat from a source or sources different from the heat of friction.
Dr. H.L. Barnes reported (Appendix E, Volume, I, Niagara Mohawk Power Corporation, 1978) the occurrence of certain euxinic sulfides accompanied with calcite along bedding as well as fracture planes; among them are mackinawite (FeqS8) and troilite (FeS)
These minerals are those to be expected from the aging of sedimentary iron sul-
- fides, and have limited stability ranges.
Mackinawite is unstable at temperatures above'40
-150 C (Appendix E, Niagara Mohawk, 1978);
however, if buried to depths of 2 kilometers or more the stability limit increases to 155 C-160 C.
This is completely compatible with the 160 C temperature values from fluid inclusions in re-crystallized quartz from the host rock.
The other line of evidence is the discovery of calcite deposited by groundwater flowing along the Radwaste Fault, and Lake Water Tunnel faults as reported in the response to Question 361.1(d) submitted in,June, 1980.
As re-ported, this calcite contained fluid inclusions with decrepitation temperatures of less than 40 C.
Dr. Barnes indicates that, in one specimen collected from the thrust fault in the tunnel, low-temperature calcite as matrix encloses breccia fragments of sandstone and milky calcite such as identified from the Cooling Tower Fault.
Because the liquid-to-vapor ratio of the milky calcite inclusion clasts is approximately the same as that for the in situ milky calcite, no alteration or re-crystallization occurred when the low-temperature calcite was formed.
Because the earliest generation of groundwater calcite always exhibits cataclastic
- texture, and because the texture, character of inclusions, their temperature values and the mineral paragensis all suggest that the groundwater calcite grobably crystallized at temperatures less than 40 C, it is highly unlikely that frictional heat adversely affected inclusion entrapment temperatures in the calcite.
A further argument from a mechanical standpoint may be made that friction on the Cooling Tower Fault could not have contributed a significant, quantity of heat such as would influence the entrapment temperatures of fluid inclusions.
Price (Appendix L, Volume III, Niagara
- Mohawk, 1978) indicated that:
1)
The rocks were saturated with brines.
2)
The minimum fluid pressure likely to be attained over long time periods is that of hydrostatic head.
3)
Mineralization of the fault can lead one to infer that the fluid pressure exceeded the hydrostatic state.
Q361.32 Continued In other 4ords, with progressive sedimentation in the Appalachian Basin, the ratio
( ~
~ of fluid pressure to the vertical geostatic pressure commonly approached a
value of 1.0 and locally could exceed this value under certain conditions.
It can be shown that normal faults could develop and that the normal stress across such faults would be negative, that. is the fault planes would be "open" thereby permitting flow of fluids along the faults with consequent precipitation of vein-filling minerals.
Under these circumstances, the contribution of friction to the value of shear resistance would be minimal.
One can extend this argument to include the thrust faults.
These faults were formed later than the normal faults, and at. higher levels in the crust.
as evidenced by abundant dilation of beds affected by the deformation.
In this instance, the value of should have been much lower than at the time of normal faulting.
- Hence, one would expect the friction to have been relatively greater during thrust-type slip, than during normal-slip.
However, the paleotemperatures were apparently less than 40 C.
Therefore, one can only conclude, once again, that frictional heat had a
negligible effect upon the inclusion entrapment temper-atures.
The temperatures more likely reflect the ambient geothermal gradient at the time the minerals were formed.
In the 1978 report, based upon the work performed by Dr. Barnes, it was concluded that the paleotemperatures recorded by the minerals were elevated initially due to increased heat flow caused by dehydration reactions typical of the zone of transition from hydrostatic temperature/pressure to lithostatic temperature/
pressure conditions in the Appalachian Basin, analogous with the Gulf Coast Basin.
It was postulated that these fluids of elevated temperature caused.
the de-velopment of a transient thermal gradient of as much as 40 C/kilometer for a period of a few tens of millions of years.
It was also stated (pages 6-14 of Volume I) that there were two other potential causes of an elevated geothermal gradient:
localized magmatic processes and crustal thinning associated with tectonic processes.
The closest known evidence of paleo-magmatic activity is in Syracuse, New York where several Jurassic kimberlite dikes are known.
Batholithic intrusions of the Monteregian Hills, Canada are known to be Cretaceous.
- However, no clear evidence of hydrothermal mineralization due to igneous activity was found in the site region.
Similarly, because progressive sedimentation in the nor-thern Appalachian Basin continued through the Mississippian period, it is improbable that crustal thinning was occurring beneath the basin rather than beneath the uplands.
Therefore, no firm reason to support the supposition that the fluids from which fault-filling minerals precipitated could have been heated above the ambient geothermal gradient can be offered.
Q361.33 In Appendix I-G of your report, you present results of uranium/thorium (U/Th) disequilibrium dates from samples of fault-plane calcite.
Indicate how this evidence affects your assessment of the most recent movements on the fault.
Discuss why the ages of 80,000 and 170,000 years before the present as determined by this technique, are not consistent with ages of faulting determined by other methods.
Our concern is that if there is sufficient uranium present in the sample to establish a
U Th disequilibrium date, then there should be sufficient uranium and lead for a U-Pb, Pb-Pb, or U-fission track date.
Any one of these methods would be much more sensitive and meaningful if the calcite is older than 200,000 years.
If possible, provide a
reliable date by one or more of the methods cited above if the 80,000 year date is to be discounted as you claim.
RESPONSE:Conclusions regarding 'the nature and age of specimens SW-1 and SW-2 which yielded the Th/U dates of 80,000 and 170,000 years, have changed in light of detailed additional geological investigations performed at the Nine Mile Point Site since 1978.
Subsequent work at the Nine Mile Point Site has revealed the occurrence of a generation of calcite which crystallized at a later time and at lower temperatures than the varieties of calcite identified in the 1978 report.
The newer calcite has been found to be present in association with zones of deformation of the low-angle thrust faults in the North Radwaste Trench, in the Intake Shaft and East Lake Water Tunnel, as well as bedding plane slip zones elsewhere on site.
The occurrence of this calcite has been documented, and specimens were collected for fluid inclusion and paragenetic analyses by Dr. H.L. Barnes.
Calcite specimens were collected from three locales:
1) the Circulating Water Piping Trench to the relocated cooling tower, 2) the North Radwaste
- Trench, and; 3) the East Lake Water Tunnel Additionally, radiometric dates and stable isotope analyses were obtained to help interpret the absolute age of the calcite.
Results are outlined herein and full details documenting the occurrence,
- analyses, and conclusions will be presented in a report to be submitted at a later date.
Dr. Barnes'aragenetic studies have distinguished as many as six varieties of calcite in the entire paragenetic sequence which is presented schematically in Figure 361.27-2.
Q361.33 Continued Dr. Barnes also identified two additional stages of defor-mation based upon microscopic mineral textures.
He termed these stages D5 and D6.
The mineral types are briefly de-scribed below.
- alent, but Type 2 was only recognized at one locality, the Circulating Water Piping Trench.
Type 1 consists of fine-grained clear calcite which has been brecciated and recemented by later calcite.
Typically, clasts of broken bedrock are incorporated within it.
Para-genetically, this group apparently is the oldest of this
- sequence, but its texture and isotopic composition indicate that it post-dates the clear calcite associated with Mesozoic normal faulting identified in the 1978 report.
Fluid inclusions were rarely found in Types 1
or 2.
The intense cataclasis of this calcite apparently liberated any inclusions which may have formed.
This group of calcite is always found on shear planes of the Radwaste and East Lake Water Tunnel thrust faults, and along brecciated zones of bedding-parallel slip onsite.
Dilated openings in the bedrock, associated with these zones of shear deformation where this mineralization
- occurred, suggested a near surface origin of Type 1
calcite.
Travertine:
Many forms of very fine-grained, travertine were observed and this mineral group is paragenetically related to Type 1 calcite in that, although never found together with Type 1, it always underlies or is infilled by later forms of calcite, as in the case of Type 1.
The travertine was deposited above the water table.
Type 1
crystallized below it.
The travertine is found on dilated bedding planes and joints in the zone of deformation of the Radwaste Fault, and has been deformed.
very fz.ne-grained calcareous material containing abundant pyrite and siliceous detritus, deposited on travertine and covered by Type 3 calcite.
This is not a dominant form of mineralization at the site.
T~pe 3:
The sperry calcite is found in a variety of habet.ts, and occurs in fractures and openings in the Type 1
breccias and travertines, and are therefore younger than the age of deformation of Type 1 (D5).
Type 3 calcite is the only one of the =lower temperature calcites that commonly contained fluid inclusions.
They are predomi-nantly liquid-phase inclusions, but have high liquid-to-vapor ratios when a vapor phase is present.
The fluid has a very low salinity, (5 to 6 percent NaCl by weight).
Ths maximum filling temperatures of these inclusions is 40 C.
Minor healed fractures in Type 3 have been observed (D6) plus chips of Type 3 have been seen to be healed by brown calcite.
Q361.33 Continued Brown Calcite:
This mineral lies on top of sparry, Type 3
- calcite, but is present only irregularly, being both dis-continuous and of varied thickness.
This mineral is interpreted to be younger than D
, and is paragenetically the youngest variety of calcite.
A e of the Calcite:
During the investigation, the absolute age of the major forms of calcite were analyzed and evalu-ated utilizing stable isotope ratios of <<3C and O plus absolute dates by the 14C and 230TH/234U methods.
The results are summarized in Table 361.33-1.
Additionally,'specimens of the drusy calcite dated by the Th/U method from the Cooling Tower Fault study were reassessed in light of the new data from the paragenetic studies on groundwater calcite.
As a result of this work, the following conclusions can be drawn with respect to Type 1 calcite, Travertine, and Type 3 calcite.
1.
Type 1 calcite is apparently the oldest of the ground-water calcites.
It is younger than calcite found at the time of normal faulting (Mesozoic) because of its near-surface origin and lower inclusion temperatures.
Carbon and oxygen isotope results (Table 361.33-1) indi-cate a typically marine source for the carbon, but a fresh.ma~ source for oxygen if the carbonate is younger than Triassic.
A marine origin of the car-bonate oxygen would be unlikely in Triassic time because the site area was emergent and eroding throughout the Mesozoic.
(ence, fresh eater appa=ently leached the older marine C from the site bedrocP, thereby explaining the greater than 36 000 year C
age (sample HK-1).
For this reason a
TH/ 34U
- date, to determine the actual age of calcite crystalli-
- zation, was performed by Dr. T.L. Ku of the University of Southern California.
His analysis yielded a less than 300,000 year age.
2.
The travertine was found to be a vadose precipitate yielding a C age of 14,180+550 year age.
This age is somewhat compatible with that yielded by shells from sample SL-10 from the
$gcustripI overburden at the site (Table 361.33-1).
The C and 0 ratios indicate a superficial source of both carbon and oxygen in fresh waters of relatively shallow circulation.
Inasmuch as glacial ice covered the site 14,000 years ago, the travertine likely formed at a later time.
This is because it formed above the water table.
Q361.33 Continued Small quantities of older carbon leached from Paleozoic carbonate clasts by water percolating through till in the overburden could have been incorporated into the travertine, thus setting back the 14C age.
Nevertheless, the travertine is of Late Wisconsinan
- age, and the paragenetic studies showed that it is deformed and fractures in it are filled by Type 3 calcite.
3.
An insufficient aTgunt of Type 3 calcite was collected for a successful C date, but the 13C ratio shows that the carbon is also from a fresh water source (Table 361.33-1)
This calcite is the same age or younger than the travertine, namely Late Wisconsinanaa Dr. Barnes re-examined the data from specimens JT-13, 43 and 44 collected from the same material which yielded the TH/U dates reported in the 1978 report (Samples SW-1 and
- 2).
He has concluded that the clear calcite in these samples is actually Type 1 calcite for three reasons:
1.
They contain single phase inclusions and inclusions with high liquid-to-vapor ratios, yielding temperatures well below 100 C.
2.
The occurrence of sulfides (marcasite, pyrite) in JT-44 closely corresponds to those seen in the Type 1 calcites
( Table 361.33-1) 3.
Ku's analyses of Type 1 in TU-1 (analyzed recently) and SW-1 and 2 (analyzed previously) showed there to be excess Th in the calcite because of the inheritance into Type 1 calcite of older clasts of milky calcite.
Additionally, fluorescence techniques applied to analysis of the Type 1 calcite has revealed that Type 1 consists of several compositional types of calcite indicative of the inheritance of older epigenetic calcites.
This means that Type 1 calcite is prejudiced for older dates.
Consequently, dating by the U-Pb, Pb-Pb, and probably the U-fission track methods is precluded because of the mixing'of young and old calcite.
- Hence, one can conclude from these new data that the clasts of breccia in Pit 1 were coated by a drusy form of low-temperature Type 1 calcite at the bedrock/till interface to be distinguished from the high-temperature epigenetic calcite which was found in every surface exposure of and throughout the cores obtained from the zone within the
Q361.33 Continued Cooling Tower Fault.
- Moreover, the results of age-dating studies show that the Type 1 calcite is less than 300,000 years old.
Therefore, the results of the 80,000 and 170,000 year dates are no longer discounted.
Furthermore, the travertine and Type 3 calcite are approximately the same age as the later stages of glacial Lake Iroquois, (approximately 11,000 years before present)
From geological evidence (Niagara Mohawk, 1978, Volume 1, Section 4.0), it is known that the main stage of buckling occurred prior to deposition of the Wisconsinan overburden and that buckling caused dilation of the upper 200 feet of the bedrock section.
It is known now that dilation and crystallization of Type 1 calcite are also associated with the development of the thrust faults.
Therefore, the time of buckling on the Cooling Tower Fault could be correlative with the beginning of thrust fault development, which, because of the postulated mechanism of deformation for this sytem of structures, must have occurred. during the final stages of an interglacial period (refer to response Q361.28; and to Sections 7.0 and 8.0, Volume 1
and Section 7.0 Volume III, Niagara Mohawk Power Corporation, 1978).
TABLE 361.33-1 RADIOMETRIC AND ISOTOPIC ANALYSES Number:
Sample:
14 Age (years) 13C 00 HK-l, TU-1 TYPE 1 Calcite Breccia 36 g 000 (HK 1)
+ 3.1 (HK-1)
HK-2 Travertine 14,180
+ 550 7.5 HK-3 TYPE 3
Sparr Calcite 4.7 SL-10*
Mollusk Shells 12,545
+ 330 6.9 18O
( /00) 230
/234 (years)
+ 21.1
+ 0.2 (HK-1) 300,000 (TU-1)
+ 22.6
+ 0.2
- From Niagara Mohawk Report,
- 1978, Uolume II.
Collected from marl in overburden along Circulating Water Piping Trench.
0,
Q361.34 Substantiate the argument presented in Section 2.6 of your Summary that swelling stresses may have resulted from fluctuations in water level in Lake Iroquois.
Show that rocks at the site can develop a swelling stress under confined conditions with water pressure varying from 1 to 10 atmospheres.
Estimate how rapidly Lake Iroquois must have drained so that residual pore pressues could approach lithostatic pressures.
In this evaluation, use the permeabilities determined by pumping test in the upper 200 feet of rock in this area.
RESPONSE
In order to characterize the swell behavior of the bedrock at the Nine Mile Point site, various swelling tests were performed.
These tests included free swell tests (uncon-fined swell) as well as oedometer ring swell tests (con-fined swell).
The results of the free swell tests were presented and discussed in the April 1978 report. It was concluded that the development of swelling strains is conditioned by the accessibility of water, and the reduction of confining in situ stress below a given value.
The results of the oedometer ring swell tests are pre-sented on Figures 361. 34-1 through 361. 34-8.
The Figures show the relations of the swell rates as a function of the first stress invarient, which is the. sum of the principal stresses.
The rock units within which the Cooling Tower Fault is developed were tested for swelling potential.
The following conclusions can be reached, based on the data presented:
(i) the swell strain rates are dependent upon the first stress invarient.
The rates decrease linearly with the increase of the stress invarient; (ii) there exists a limiting value for the first stress invarient beyond which swell rate is equal to zero.
The limiting value indicated by the results appears to be larcener than approximately 450 pounds per square inch (first stress invarient corresponding to hydro tatic pressure equal to 10 atmospheres)
Hence, it follows that rocks present at the site can develop a swelling stress under confined conditions with water pressure varying from 1 to 10 atmospheres.
However, in order to develop these strains, the in situ
'edrock stress must be reduced below the limiting value of the stress invarient.
From observations of bedrock dilations onsite, it is clear that the required reduction occurred simultaneously with the deformation.
The residual pore pressure may have been important in triggering this deformation.
Q361.34 Continued The deformation must have been accompanied with a stress drop and the development of a stress gradient.
As a consequence of the deformation, permeability of the bedrock was substantially increased and the pore pressure was reduced.
Following that, the swelling of the bedrock could have taken place, pro-vided that access to water was maintained.
Available data regarding the drainage of Lake Iroquois do not allow a more precise estimate than already pre-sented in Plate 1-14 of Volume II of the April 1978 report.
Calculations of the rate of drainage would be hiahlv speculative, requiring knowledge of the outlet cross sectional area and inflow rate.
Additionally, changes in bedrock permeability occurred as a result of the draining of Lake Iroquois as evidenced by the presence of lacustrine deposits on bedding planes and fractures to below 200 feet.
Therefore, it would be inappropriate to utilize present. permeability values determined in the upper bedrock units. It is felt that the load casts and sand dikes observed in the Sandy Creek sediments above the Cooling Tower Fault provide sufficient evidence that, Lake Iroquois drained relatively quickly and pore pressures probably did approach lithostatic pressures.
ERlI-CI Eil Cl-ELE Cil I
Cl O N )(
CL Cl ESTIMATED UPPER BOUND 0
FREE SWELL TESTS SWELL STRAIN/SWELL STRESS TESTS A
M giC" m
Z z
m A
Pl Tl 0
O ZCZ y Z l
ELT <o O r m
m 0
ESTIMATED LOWER BOUND ESTIHATED AVERAGE o0 OZ 0
100 200 300 400 500 FI RST STRESS I NVARIANT (PS I )
6oo 700 8oo HORIZONTAL SWELL STRAIN RATE V.S. FIRST STRESS INVARIANT-TRANSITION ZONE
20 C)
CB C)
IC)
ELE 16 12 0
FREE SWELL TESTS SWELL STRAIN/SWELL STRESS TESTS ESTIMATED UPPER BOUND z
2 m
O m
ELj OCI-ELE 8
4 ESTIMATED LOWER BOUND ESTIMATED AVERAGE qM C
Pl ES o
o xcz x
z A
o r m
m g7 100 200 300 4oo 500 FIRST'STRESS INVARIANT (PSI) 6oo 700 8oo OT O
D Oz VERTICAL SWELL STRAIN RATE'.S.
FIRST STRESS INVARIANT "TRANSITION ZONE
0 FREE SWELL TESTS x
x SWELL STRAIN/SMELL STRESS. TESTS C5 C)
I C)
X ESTIMATED UPPER BOUND X
X 0D r
ES ogCZ y Z -E g
ELS r
'ES O
o r m
m I
CSM CE' ESTIMATED LOWER BOUND X
ESTIMATED AVERAGE oO TS I0X 0
100 6oo 200 300 400 Soo FIRST STRESS
.I'NVARIANT (PSI)
HORIZONTAL SWELL STRAIN RATE V.S. FIRST STRESS INVARIANT-GREYWACKE 7oo Soo
12 X
0 FREE SWELL TESTS x
x SWELL STRAIN/SWELL 'STRESS TESTS ESTIMATED UPPER BOUND Lal X
m 0D p
EST I HATED LOWER BOUND EST I HATED AVERAGE ll MnCZ Pl ld ld C'
xo o
gC2 D Z -l x
z O
0 Im m
o0 oK 100 200 300 400 500 FIRST STRESS INVARIANT (PSI) 6oo VERTICAL SWEI L STRAIN "RATE V.S. FIRST STRAIN INVARIANT"GREYWACKE 700 8oo
0.
FREE SWELL TESTS
~ SMELL'TRAIN/SMELL STRESS TESTS 5
I ED ESTIMATED UPPER BOUND 4
3 I-ED t4 2
ESTIMATED
'VERAGE ESTIMATED LOWER BOUND 0
200 4oo 6oo goo FIRST STRESS INVARIANT (PSI) 1000 1200
't HORI7.ONTAL SWELL STRAIN RATE V.S. FIRST STRESS INVARIANT-PULASKI B & C NINE MILE POINT NUCLEAR STATION UNIT 2
NIAGARA MOHAWK POWER CORP.
FIGURE 361
~ 34-5
Cl o
C5 25 0
FREE SWELL TESTS SMELL STRAIN/STRESS TESTS 20 15 LEE EA CJ I-EAJ)I X
m cr m
10 ESTIMATED LOWER BOUND ESTIMATED UPPER BOUND ESTIMATED AVERAGE o
ozcz 7C g
ro <
D O
o r j
m m
0 100 200 300 400 500 FIRST STRESS INVARIANT 6oo 700 8oo Ao VERTICAL SWELL STRAlN RATE V.S.
FIRST STRESS INVARIANT-PULASKI 8 5 C
0
10 C5o 0
FREE SWELL TESTS DATA ON SHALE SAMPLES FROM PULASKI C
(TEST NOS. TD-1"13, TD-1-14, TD-1-16) x K SWELL STRA[M/SWELL STRESS TESTS Io 6
ESTIMATED UPPER BOUND X
K TTl Cl r m
ot4 CE' EST I MATED LOWER BOUND qM ClCX
~
m OZC2 p Z D
O 0
I ETl 100 200 300 4oo 500 FIRST STRESS INVARIANT (PSI) 6oo 700 Soo OS O
O.Z HORIZONTAL-SWELL STRAIN RATE V.S.. FIRST STRESS INVARIANT-WHETSTONE GULF FORMATION
a
30 EO C5 C)
?:
I C) 25
=20 0
FREE SWELL TEST DATA ON SHALE SAMPLES FROM PULASKI C
(TEST NOS. TD-1-13, TD-1-14, TD-1-16)'WELL STRAIN/SWELL STRESS TESTS ESTIHATED UPPER BOUND 15 n
C m
X X
ETl D
Q m
I TTo gCZ Z
O o r EST I-Lll 10 5
EST I HATED LOWER BOUND ESTIHATED.
AVERAGE Cd td I
CO oo oX 0
200 100 300 4oo 5oo 6oo FIRST SWELL INVARIANT (PSI)
VERTICAL SWELL STRAIN RATE
'V.S. FIRST STRESS INVARIANT-WHETSTONE GULF FORMATION 700 Soo
Q361.35:
If the draining of Lake Iroquois provides a plausible explanation for the Quaternary movement along the deformation structures at the site, then similar features should exist at other locations similarly affected by the draining of Lake Iroquois.
The existence of similar structures only at such locations would provide evidence for your hypothesis.
Accordingly, determine the known distribution of such structures from a literature search and present a discussion as to whether this distribution favors your hypothesis.
RESPONSE
In the region affected by the draining of Lake Iroquois, numerous buckles of postglacial age were reported (Niagara Mohawk Power Corporation,
- 1978, Volume I, Section 2.0, and Volume II, Section 3.0). It was also reported (Volume I, Section 2.2.3.5) that the buckles were of two types:
chevron-style, and sinusoidal.
Sutton's (1951) work in western New York State indicated that a chevon-style buckle:
"typically coincides with a pre-existing fracture or fault, which is situated along the axial plane."
A classic example of the relationship between buckles and faults is the structure exposed at Thirtymile Point near Lyndonville, New York.
The locations of postglacial deformational features in the Lake Ontario region are illustrated on Figure 2-4, Volume I of the April 1978 report.
None of the defor-mations reported appears to be as complex as that noted along the Cooling Tower Fault, but the lack of significant bedrock exposures along the southern shore of Lake Ontario precludes a detailed assessment of the distribution and complexity of similar structures.
REFERENCES Niagara Mohawk Power Corporation, 1978, Nine Mile Point Nuclear Station, Unit 2, Geologic Investigation,
- Scriba, New York.
- Sutton, R.G.,
1951, Stratigraphy and Structure of the Batavia Quandrangle, Proc.
Rochester Acad. Sci., v. 9, p. 348-408.