ML18003A402
| ML18003A402 | |
| Person / Time | |
|---|---|
| Site: | Harris  |
| Issue date: | 01/24/1979 |
| From: | Mcduffie M CAROLINA POWER & LIGHT CO. |
| To: | Harold Denton Office of Nuclear Reactor Regulation |
| References | |
| NUDOCS 7901300175 | |
| Download: ML18003A402 (15) | |
Text
em'arolina Power 6 Light Company January 24, 1979 Mr. Harold R. Denton, Director Office of Nuclear Reactor Regulation United States Nuclear Regulatory Commission Washington, D. C.
20555 SHEARON HARRIS NUCLEAR POWER PLANT, UNIT NOS. 1, 2, 3, AND 4 DOCKET NOS. 50-400, 50-401, 50-402, AND 50-403 GEOLOGICAL FEATURES IN THE MAIN DAM CORE TRENCH
Dear Mr. Denton:
Carolina Power
&. Light Company (CP&L) reported. the existence of a geologic anomaly located in the main dam core trench between Stations 2+90 and 3+90 on November 9, 1978.
This anomaly was identified as Fault: A.
On November 16, 1978, CP&L reported two separate geologic anomalies located in the main dam core trench between Stations. 2+90 and 3+90.
These anomalies were identified as Fault Group B and Fault C.
On November 29,. 1978, CP&L submitted a report discussing Fault A and.Fault Group B'nd, committed. to provide a report on Fault C upon completion of a geologic investigation.
On December 1,. 1978, CP&L reported the existence of another geologic feature, Fault Group D,, in the main dam coze trench between. Stations 2+90 and 3+90.
During the NRC personnel site visit: on December 8,. 1978, Mr. Tom Cardone, NRC staff geologist, was given the opportunity to view. these faults.
Also during the December 8, 1978, NRC site visit, Fault A2 was identified in the main dam core trench.
On January 19, 1979,.CP&L repozted the existence of Fault A3 located in the main dam core: trench southeast (downstream) wall.
Fault A3 was originally thought to be an extension. of Fault C, which had previously been reported on November 16, 1978, until the geologic investiga-tion revealed it was a separate geologic feature.
This report discusses the final evaluation. of Fault. C,. Fault Group D, and Fault A3.
The status of the Fault A2'eologic investigation presently underway is described',.
and a final report will be submitted upon completion of the. investigation.
In order. to more clearly identify the geologic features which we are reporting,, we have refined fault nomenclature for this and subsequent reports in order to classify faults of similar, orientation and sense of slip under the same letter designation (e.g;, Fault Set "A"), with subscripts being used to distinguish faults within. the fault sets (e.g., Faults A, A2, A3, etc).
Within. a set, closely spaced faults of similar orientation, sense of slip and origin are labeled as a group.
Thus we had previously described "Fault Group B" in our report of November 29, 1978.
A geometric classification approach was described to Mr. Tom Cardone, NRC staff geologist, during the inspection of December 8, 1978.
ygLIt50@ Dog(D (ILE COP
-'tt Feyettevitle Street
~ PO. Box l55t
~ Raleigh. t4. C, 27602 g5o ( 'Zca< qE
Mr. Harold R. Denton January 24, 1979 In this report two other faults of similar orientation to Fault A have been labeled as A2 and A3.
Fault A2, which was shown to Mr. Cardone during his inspection on December, 8, 1978, will be described in more detail in a subsequent report since it extends into the upper, unexposed portion of the core trench.
Fault A3 on the downstream wall of the trench was initially thought to be an extension of Pault C before the wall of the trench was ade-quately exposed.
Figure 1 shows the location of the core trench where the faults occur.
Pigure 2 of this report, previously sent to you as "Main Dam Plan Geologic Map of Core Trench Sta 2+90 to 3+90" and the key Pigure 3 have been revised herein to identify Fault Group D, Fault C, and Fault A2.
Pigure 2A is a map of the south-eastern wall of the trench which shows Pault A3.
Table 1 shows the status to date on reporting of-foundation features and faults at the main dam.
Fault C
Pault C, has an average strike of N20 E, dips steeply to the southeast and terminates within the core trench'(No.
27 and 58) as shown on the geologic
- plans, Figure 2 and 2A and as described on Figure 3.
The fault bifurcates into two planes with similar orientations at several locations as. shown on the plan view map and Photo 1.,
Fault C displaces three epidote veins (No. 21 and 25) as shown on Photo 1.
The strike<< separation of these veins ranges from nine inches to less than one: inch (No.: 24, 26, 46).
As can be observed from Figure 2, the amount of separation is decreasing to the northeast indicating that the fault is dying out in. this direction as shown on Figure 2A.
Pault C terminates at fracture zone No. 17.
Another fracture with a similar orientation to Pault C begins on the south side of fracture zone No.. 17, but it does not. offset an aplite dikelet
{No. 48) nearby and: it also terminates locally (No. 49).
Fault C is also cross-cut by two NE trending fractures and one. NW trending. fracture with no offset.
An orange-red coloring along the trace of Fault C and a 1 to 2
mm wide, milky-white layer within the fault plane suggest that Pault C has been filled with hydrothermal minerals during late stage thermal activity.
Fault Group D is composed of four closely, spaced fault planes, which offset a small. pegmatite dike at the main dam centerline near station 3+32.
See Photo 2 and Pigures 2 and 3.
Maximum separation is 2.2 feet along a N40'W set of planes.
True slip as indicated, by slickensides is probably less than one foot.
Lengths of the planes are less than six feet..
A pod of massive biotite which is not offset has been deposited across the fault planes.
Fault A2 Fault A2 as shown on Photo 3 and Pigure 2 has an orientation of N34'E, 81'SE.
This fault shows right lateral strike separation of one to four inches (No. 38, 39, 40).
Fault A2 is located en echelon right to Fault A and is filled
Mr. Harold R. Dento in places with a black mineral very similar to that noted for Fault A.
The amount of strike separation along Fault A2 is decreasing to the northeast where the fault terminates at station 3+02.
To the southwest Fault A2 has yet to be traced as cleaning has not progressed above station 2+90.
Fault A3 Fault A3 is located in the southeast wall of the core trench and has an orientation of N40'E, 82'SE.
(See Photo 4.)
This fault offsets the same epidote vein (No. 9) as does Fault A.
Fault A3 shows four inches of right lateral strike separation.
The fault terminates to the northeast near station 3+47 and cannot be traced more than one foot beyond the offset to the southwest.
Xf the plane of Fault A3 were projected to the southwest for several feet, it would cross a
quartz-feldspar-biotite vein and an. aplite dike.
Neither of these markers were found to be offset by any of the northeast-southwest trending fractures in the southern wall of the core trench.
Fault C, Fault Group D, and Fault A3 show small displacements (all probably less than one foot); cannot be traced beyond the core trench; and either contain minerals that were probably deposited during ancient thermal activity or, when the fault alignments are pro]ected a few feet, they encounter veins with hydrothermal minerals which have not been displaced.
Thus, like Fault A and Fault Group B, of the November 29, 1978, report, the small displacements, short lengths and mineralization along the fault planes indicate that these three faults developed prior to ancient thermal activity.
Attachment B of the CP&L report of October 17, 1978, to the NRC on "Geological Feature at the West Wall of Main Dam Diversion Conduit" documented. that the last deformation-mineralization processes would have occurred over 225 million years ago.
This logic demonstrates that Fault C, Fault Group D, and Fault A3 cannot be capable faults as that term is defined in Appendix, A to 10CFR100.
Fault A2 willbe further described in a future report although it is similar to Fault A and almost certainly not capable as defined by 10CFR100, Appendix A.
Yours very truly,,
M. A. McDuffie Senior Vice President Engineering
& Construction RGB/mf Attachment cc:
Mr. James P. O'Reilly
TABLE 1 MAIN DAM FOUNDATION FEATURES AND FAULTS DISCOVERED TO DATE Feature/Fault Deformational Feature Schistose Zone Location Spillway Sta 15+41 Conduit Sta 2+55 Report to NRC Initial Written 12/8/77 12/15/77 9/19/78 10/17/78 NRC Ins ection 12/14/77 9/19/78 Fault A Fault Group B
Core Trench Sta 3+10 Core Trench Sta 3+10 11/9/78 11/29/78 11/16/78 11/29/78 12/8/78 12/8/78 Fault C
Fault Group D
Fault A2 Fault A3 Core Trench Sta 3+60 Core Trench Sta 3+32 Core Trench Sta 3+00 Core Trench Wall Sta 3+40 11/16/78 12/1/78 12/8/78 1/19/79 11/16/78 This Report This Report Pending This Report 12/8/78 12/8/78 12/8/78 12/8/78 Offsets in Spillway Spillway Sta 11+70 Sta 12+02'ta 12+10 12/20/78 Pending Pending
0
PHOTO 1
Fault C.
View south at core trench Station 3+60.
Note offsets of epidote veins and that the fault bifurcates between the veins.
No. SHNPP Main Dam 12/78-4 12/20/78
PHOTO 2 Fault Group D.
View southwest near core trench centerline at Station 3+32.
Note termination of faults at biotite pod.
No. SHNPP Main Dam 12/78-5 12/20/78
~'4 4
bP
~g
~
PHOTO 3 Fault A2. View south at core trench Station 3+00. Fault extends beyond sandbags.
No. SHNPP Main Dam 12/78-6 12/20/78
PHOTO'4'ault A3 shown offsetting epidote vein (No. 9).
View of southeast wall of core trench at Station 3+40.
No. SHNPP Main Darn 12/78-T 12/20/78
~ese(~Q U>2>>
O
<l R
<v I
j flsl>s I<fv)I p
..::.:......see.
0<.I<I Us Jtl V )5 ff<lff:;<<rf<.IS(s)pl<>If(XnnllhfIII,I II~ I!>
Ve e> Ae < It~ ~ I I I AN)FF S(F. F)fiUA( 11<)A ).( Y Ill<i(IIII)<'el<:.">I(:Ilf>fl less<< slf ssl Ih Is< I <v<< s ~ I~ ss< hs, ~ sv,<sh>N f is>Iles Asses ss F>><<><I I Is) Its<
<sf<>vs'Is's>S
<sf IU< lus
s <As)<<+< I Al le<<I << rA<s<"
IA>'As>s A I<rsssl
~ vs>efhsss AI><> I I, sess>v's>><t>,III
~ I>AI><> %<s'I< ~ ess ~ sl I, I'S>>e
's
<wsteslssl'\\<'> Isl
<4>f Alt<tflllh<lf<ISIAA'IINIIS)s'A)II'(Af>l te(AIN l)AII(
I I AL4 I'((l(I)fi)(')elhi S(sl)ll(EASI WALI ()F ( I)lf( 1(I)tlf ll
.)<IN) Iss I'lifl
~
I IIh I ~ I 'II I./II I S
<U<< II'IIv IIIh I I I ~
s
~
~"
~
Ie I
I I lssllhl AA
k
~
~
p
)
FIGURE 3 KEY TO PLAN GEOLOGIC MAP CORE TRENCH STATION ~ 2+90 TO 3+90 DOWNSTREAM SIDE OF CENTERLINE SCALE:
1 INCH ~ 5 FEET (REVISED 12t20ff8/
B.
C.
Fault A Oriented N34E 75SE. Terminates within core trench.
Fault A2 Oriented N34E 81SE.
Fault A3 Oriented N40E 82SE. Terminates within core trench.
Fault Group 8 En echelon set of four fractures with an average strike of NBOE.
Fault C Average orientation of N20E and a steep dip to the SE.
Fault Group D Four closelycpaced fractures with an average orientation of N40W.
1 2
3 4
5 6
7 8
9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24.
25 26 27 28 29 30 31 32 33 34.
35 36.
37.
38.
39.
40 41.
42.
43.
45.
46.
47.
48.
49.
50.
51.
5 55.
56.
57.
58.
a dark green-The average to have the to cross the fault plane.
ltA Fault A terminates.
Aplite dikelite.
1.0 inch of right-lateral strike separation of aplite dikelet.
3.0 inches of right.lateral strike separation of aplite dikelet.
3.8 inches ot right.lateral strike separation of aplite dikelet.
1.0 inch of right-lateral strike separation of aplite dikelet.
6.0 inches of right lateral separation of aplite dikelet along Fault A.
3.0 inches of right-lateral strike separation of epidote vein along Fault A.
Epidote vein 1 to 3 inches wide. Reaches maximum width between Stations 3+20 and'3+30.
Epidote vein 0.5 to 2.0 inches wide.
Near Station 3+21, apidote vein intersects a NW-trending fracture which is filledwith gray mineral with a thickness of 1 to 5 mm.
Quartz-feldspar vein.
No offset of the mineral-filled NW.trending fracture.
Aplite dike let.
Aplite dikelet terminates.
Massive biotite vein, 2 to 3 inches wide. Exposed along two parallel NE trending fractures.
Pods of granitic pegmatite very similar in texture and mineralogy to the granitic gneiss.
Zone of highly-fractured rock, 2 to 8 inches wide.
This zone is formed by the Intersection of a conjugate pair of fractures.
orientation of the conjugate pair is N40W 70NE and N75W 55SW.
SIickensides on some of the N40W planes were observed same orientation as those of Fault Group D. A quartz. feldspar vein on the upstream side of the core trench was observed fracture zone with no offset.
Quartz. feldspar vein. The vein crosses the aplite dikelet with no offset. Crystal growth is perpendicular to the vein well.
Fracture is completely healed and can be traced no further.
Small granitic pegmatite lens.
Epidote vein, 3 to 5 inches wide.
Epidote vein bifurcates into two fractures with no epldote along either fracture.
Epidote vein thins into fracture with little or no mineralization.
9.0 inches of right-lateral strike separation of the epidote vein along Fault C.
Epidote vein, 1 to 2 inches wide, which thins to a fracture with a thin mineralized layer.
4.0 inches of right.lateral separation of the epidote vein along Fault C. Some right lateral drag observed along the trace of the Fault C cannot be traced beyond this point.
Southeast end of a quartz. feldspar vein.
Closely:spaced set of joints.
Closelywpaced set of joints with average strike and dip of N40E and 40SE respectively.
Fault A terminates.
Closely.spaced set of joints trending about N30W and dipping steeply to the NE.
Fault C bifurcates and becomes a single fracture where it offsets epidote vein (No. 25).
Granitic pegmatite lens is offset by less than one inch by a NW.trending fracture that terminates locally.
Small granitic pegmatite pods.
2.2 feet of right.lateral strike separation of granitic pegmatite pod along Fault Group D.
Fault A2, which displaces small epidote and quartz. feldspar veins. Orientation and sense of strike separation is the same as Fau 1.0 inch ot right lateral strike separation of a quartz feldspar vein along Fault A2.
2.5 inches of right.lateral strike separation of an epidote vein along Fault A2.
4.0 inches of right.lateral strike separation of a quartz-(eldspar vein along Fault A2.
Large biotite pod, with some quartz along its edge, which has been deposited across Fault Group D and is not offset.
Fault Group D terminates at the biotite potL Massive biotite vein.
NE.trending fracture with similar orientation to Faults A and A2.
NE trending fracture with similar orientation to Faults A and AZ.
Epidote veinlet with less than 1.0 inch of right lateral strike separation along Fault C.
Fault A2 terminates.
Aplite dikelet.
Intersection of Fault A3 and a fracture with similar orientation to Fault C.
4.0 inches of right lateral strike separation of an epidote vein (No. 9) along Fault A3.
Fault A3 cannot be traced beyond this point.
Fault A3 terminates.
NE-trending fractures. with a similar orientation to that of Fault A3, crossing epidote vein (No. 9) with no offset.
NE.trending fractures, with a similar orientation to that of Fault A3, crossing epidote vein (No. 9) with no offset.
Aplite dike.
Quartz-K feldspar-biotite vein (pegmatitic) which projects across a fracture of Fault A.type orientation with no offset.
Fracture filled with a 1 to 4-inch thickness of quartz, opaques, aplitic material, and epidote.
Fault C terminates.
4g 4I
~ W4% I~I&A~
~4ll AIP
~ IW4I W4IIW4I 0 -~l C
WW444A&II4IOIk II
~
\\CA4 I~
(I A III~ ~
IWAIA4AI 4AWAA4 COAA 1III'
f
- .e
~ ee l
'l C,
le I
>> ~
~el 5 MMC/
\\
,~7;
/
/ MMM ~a r
5CC1 e I
I I,
lg
))
C I
I I
t l
~ e MMl
'l ~
l eMM O M N4 eM le el M
~ Orle
~CM oeoeooeceeer oeeeHC Me ooe oe core e OMcee ',
OIL OMe ~
~~U Mee MMeeo Ke eeM
~ el%ill leMee
'lllMe