ML20054E154
| ML20054E154 | |
| Person / Time | |
|---|---|
| Site: | Ginna  |
| Issue date: | 04/19/1982 |
| From: | Maier J ROCHESTER GAS & ELECTRIC CORP. |
| To: | Crutchfield D Office of Nuclear Reactor Regulation |
| References | |
| TASK-02-04.D, TASK-2-4.D, TASK-RR NUDOCS 8204260194 | |
| Download: ML20054E154 (8) | |
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ROCHESTER GAS AND ELECTRIC CORPORATION
- 89 EAST AVENUE, ROCHESTER, N.Y.14649
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April 19, 1982
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Director of Nuclear Reactor Regulation M'U'"
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Attention:
Mr. Dennis M. Crutchfield, Chief q;f rEIffc(\\"
Operating Reactors Branch No. 5
/
U.S.
Nuclear Regulatory Commission Washington, D.C.
20555
Subject:
SEP Topic II-4.D, Stability of Slopes R.
E.
Ginna Nuclear Power Plant Docket No. 50-244
Dear Mr. Crutchfield:
This letter is in response to your February 19, 1982 letter regarding SEP Topic II-4.D.
In your evaluation of this topic, it was noted that the NRC could not conclude that the slopes on the Ginna site are stable.
Although RG&E believes that the slopes are stable, we have performed an evaluation to determine the effects on safety-related structures even if the slopes did fail.
As noted in the attach-ment, the postulated failure of the slopes would not affect any safety-related structures, systems, or components.
- Thus, stability of slopes as related to the Ginna site is not con-sidered a safety concern.
Very truly yours, k
M J
n E. Maier ho35
//
i 820426011Y
J
Attachment:
Calculation of Internal Friction Angle, Cohesion and Travel Distance of a Mud Wave Generated From Slope Failure for SEP Topic II-4.D, Stability of Slopes, R. E. Ginna Two onsite slopes at the R. E. Ginna Nuclear Power Plant have been identified whose failure may be a safety concern.
Boring #1 and Boring #3 of the PSAR subsurface investigation have been accepted to represent the subsurface soil conditions of these slopes.
The stratum that is the focus of primary concern has been designated as the CL class material.
The CL material taken from Boring #101 was subjected to two Triaxial Compression Tests to determine the properties of the CL material.
This mode of testing produces a failure plane that more closely resembles an actual failure plane than the results of the direct shear tests conducted on the CL material obtained from Boring #1 and
- 3 The results of the Triaxial Compression Tests can be seen on the copy of Boring Log #101 attached to this submittal.
A copy of the method of performing the Triaxial Compression Test is also attached.
In the first test, a constant normal pressure, o, of 1200 pounds per square foot was applied until failure was achieved.
The shearing strength was calculated to be 600 pounds per square foot for the CL material during this test.
In the second test, the constant normal pressure a was increased to 1800 pounds per square foot, when failure occurred.
The shearing strength of this sample also was calculated to be 600 pounds per square foot.
The shearing resistance S of the soil subjected to the Triaxial Compression Test is equal to the constant of cohesion C plus the product of the normal stress on the surface of sliding,.
o, and the tangent of the angle of internal friction $.
In other words, S = C + o tan $, known as coulomb's equation.
The log of Boring #101 shows us that although the sample is subjected to two different normal stresses, the calculated shearing resistance of the soil in both tests is the same.
The shearing resistance S of this material can only be c_1culated after & and C have been l
experimentally determined.
Since the values of 4 and C were not stated on the Boring Logs, the actual slope stability due to the onsite CL material cannot be derived.
However, possible combinations of the cohesion C and the internal angle of friction 4 that correspond to a factor of safety along different possible failure surfaces can be evaluated.
l For instance, it can be shown that if the shearing resistance of the material can be fully attributed to cohesion, that is if the soil is a very soft clay, then the internal angle of friction equals zero.
In this case 600 = C + tan 0* or C = 600 psf.
On i
the other hand, if the material is cohesionless, that is, a dry l
l t
' sandy material with C = 0, then 600 = 0 + 1800 x tan 4 or & = 18.4*.
These two examples define the extreme limit combinations of cohesion C and the internal angle of friction 4 f different A relationship between the critical height h slopesandthecohesionCofclaywasdevelopedbhRGregory P.
Tschebetarioff in Foundations, Retaining and Earth Structures @
1973, McGraw-Hill Inc.
This relationship has been developed into charts from which one can estimate the length of travel of a possible mud slide which may occur in the case of slope failure.
A copy of these. charts is included as' Figure 1.'
The full. range of the possible developed cohesion C was evaluated to estimate the length of travel that each failure would incur for the corres-ponding calculated internal friction angles.
The results of these calculations for both triaxial tests are included with this evaluation.
These calculations show that even in a worse case slope failure mode, the maximum distance traveled by the generated mud slide will be only 18.0 feet.
Slope failure on the eastern slope will generate a mud wave that will propogate no closer than 95.0 feet from the east side of the screenhouse.
Slope failure on the western slope will generate a mud wave that will propogate no closer than 210.0 from the northwest corner of the turbine building.
Based upon this evaluation, we conclude that the onsite slopes at the R. E. Ginna plant present no threat to the safe operation of the facility.
4
- Boring #101 - Triaxial Compression Test 26 ft. deep S = 600 psf W = 22.6%
o = 1800 psf yD = 106 pcf
= 137.0 pcf YT Angle of repose, $' = 7.59*
Normal stress, o' = 10 ft. 137.0 pcf = 1370 psf Effective cohesion, C' = Apparent cohesion, C Shearing strength S = C + o tan $ or C = S - a tan &
Shearing stress t = C' +o' tan $'
Safety factor, S.F. =f=C
+o' n$'
Distance Traveled
- C psf S.F.
Upon Failure 26.6 24*
21*
18.4*
O 3.28 0'
17" 50 2.58 4.6 15*
118 2.00 9.2 12 217 1.50 18.0' 10*
283 1.29 16.0' 8*
347 1.13 8.8' S
443 0.96 0
0*
600 0.77 0
- Figure 7-6a II, pg. 284, Foundations Retaining and Earth Structures, Gregory P. Tschebetarioff 0 1973 McGraw-Hill.
1 Boring #101 - Triaxial Compression Test 20 ft. deep S = 600 psf W = 24.5%
o = 1200 psf yD = 102 pcf
=
yT 135.1 pcf Angle of repose, $' = 7.59" Normal stress, c' = 10 ft. 135.1 pcf = 1351 psf Effective cohesion, C'
= Apparent cohesion, C Shearing strength S = C + o tan 4 or C = S - a tan $
Shearing stress t = C' +o' tan $'
Safetyfactor,S.F.={=C
+o' n$'
Distance Traveled
- C S.F.
Upon Failure 26.6 0
3.76 0
24 66 2.44 3'
21*
139 1.88 7.4 18*
210 1.54 14.8' 17*
233 1.45 16' 15 278 1.31 11.1' 12*
345 1.14 9.8' 7*
453 0.95 0
4*
516 0.86 0
0*
600 0.77 0
- Figure 7-6a II, pg. 284, Foundations Retaining and Earth Structures, Gregory P. Tschebetarioff 0 1973 McGraw-Hill.
284 Unbrac d Cuts. Slope Stabihty [ Art. 7 2 r
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500 1000 1500 2000 2500 3000
, C. lb per sq ff,
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0.5 1.0 1.5 c, fans per 54 ft or kgg/cm' l-f" f5of tt-Medium -------Stiff--------b--Very stiff---
Consistency of clay if is rzj' 30 4rss are.o)
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,c,lb per sq ft,
0 0.5 1.0 L5 c, tons per sq ft or kgf cm'
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} Veryf5 oft h-Medium -------Stiff--------+-- Very stiff---
soft Consistency of clay Fig. 7.s. Four diagrams illustrating the relationship between the critical height L' of different slopes and the cohesion c of a clay weighing 100 lb,ft8 (1.6 gr/cm ).
(Dneloped 8
from Taylor, Ref. 330.)
Figure 1
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M ETIIODS OF P ERFORMING UNCONFINED COMPRESSION AND TRIAXIAL COMPRESSION TESTS l'
Tile SilEARING STRENGTitS OF SOILS ARE DETERMINED Fl q
p FROM Tile RESULTS OF UNCONFINED COMPRESSION AND TRIAX1AL COstPRESSION TESTS. IN TRIAXIAL COMPRES-SION TESTS Tile TEST METilOD AND Tile MAGNITUDE OF 4QW i
Tile CONFINING PRESSURE ARE CIIOSEN TO SIMULATE kg
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f4IMl ANTICIPATED FIELD CONDIllONS.
f UNCONFINED COMPRESSION AND TRIAXIAL COMPRESSION I
TESTS ARE PERFORMED ON UNDISTURBED OR REMOLDED g
i I
SAMPLES OF SOIL APPROXIMATELY SIX INCllES IN LENGTil i
AND TWO AND ONE-ilALF INCllES IN DIAMETER. Tile TESTS I
t b
ARE RUN EITilER STRAIN-CONTROLLED OR STR ESS-4
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4 i
CONTROLLED.
IN A STRAIN-CONTROLLED TEST TIIE U
j (
I s
SAMPLE IS SUBJ ECTED TO A CONSTANT RATE OF DEFLEC-TION AND Tile RESULTING STRESSES ARE RECORDED. IN
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A STRESS-CONTROLLED TEST Tile SAMPLE IS SUBJ ECTED
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TO EQUAL INCREMENTS OF LOAD TITil EACll INCREMENT
[
DEING MAINTAINED UNTIL AN EQUILIBRIUM CONDITION w
i WITil RESPECT TO STRAIN IS AClllEVED.
YlELD, PEAK, OR ULTIMATE STRESSES ARE DETERMINED TRIAXIAL COMPRESSION TEST UNIT FROM Tile STRESS-STRAIN PLOT FOR EACil SAMPLE AND i
Tile PRINCIPAL STRESSES ARE EVALUATED. Tile PRINCIPAL STRESSES ARE PLOTTED ON A MOllR'S l l
CIRCLE DIAGRAM TO DETERMINE TIIE SilE ARING STRENGTil OF Tile SOIL TYPE BEING TESTED.
l I
UNCONFINED COMPRESSION TESTS CAN BE PERFORMED ONLY ON SAMPLES WITil SUFFICIENT CollE-
- 7, SION SO TilAT 111E SOIL WILL STAND AS AN UNSUPPORTED CYLINDER. TilESE TESTS tlAY DE RUN AT !
NATURAL MOISTURE CONTENT OR ON ARTIFICIALLY SATURA LED SOILS.
IN A TRIAXIAL COMPRESSION TEST Tile SAMPLE IS ENCASED IN A RUBBER MEMBRANE, PLACED IN A I TEST CllAMBER, AND SUHJECTED TO A CONFINING PRESSUkE TilROUGilOUT Tile DURATION OF Tile g
TEST. NORMALLY, Tills CONFINING PRESSURE IS MAINTAINED AT A CONSTANT LEVEL, ALTilOUGli FOR SPECIAL TESTS IT MAY BE VARIED IN RELATION TO Tile ME ASURED STRESSES. TRIAX1AL COMPRES-SION TESTS MAY DE RUN ON SOILS AT FIELD MOISTURE CONTENT OR ON ARTIFICIALLY SATURATED SAMPLES. Tile TESTS ARE PERFORMED IN ONE OF Tile FOLLOWING TAYS:
l p
F UNCONSOLID ATED-UND R AINED: TIIE CONFINING PRESSURE IS IMPOSED ON Tile SAMPLE i
AT Tile START OF Tile TEST. NO DRAINAGE IS PERMITTED AND Tile STRESSES WillCll ARE MEASURED REPRESENT Tile SUM OF Tile INTERGRANULAR STRESSES AND PORE WATER PR ESSUR ES.
CONSOLIDA TE D-UNDR AIN ED: Tile SAMPLE IS ALLOTED TO CONSOLIDATE FULLY UNDER Tile APPLIED CONFINING PRESSURE PRIOR TO Tile START OF Tile TEST. Ti!E VOLUME CilANGE IS DETERMINED BY MEASURING Tile TATER AND/OR AIR EXPELLED DURING
'CONSOLID ATION. NO DRAINAGE IS PERMITTED DURING Tile TEST AND Tile STRESSES WillCil ARE MEASURED ARE Tile SAME AS FOR Tile UNCONSOLIDATED-UNDRAINED TEST.
DR AINED: Tile INTERGRANULAR STRESSES IN A SAMPLE MAY DE MEASURED BY PER-FORMING A DRAINED, OR SLOT, TEST. IN TI!!S TEST Tile SAMPLE IS FULLY SATURATED AND CONSOLIDATED PRIOR TO Tile START OF Tile TEST. DURING Tile TEST, DRAINAGE IS PERMITTED AND Tile TEST IS PERFORMED AT A SLOR ENOUGli RATE TO PREVENT Tile HUILDUP OF PORE TATER PRESSURES. Tile RESULTING STRESSES WillCll ARE MEAS-URED REPRESENT ONLY Tile INTERGRANULAR STRESSES. TIIESE TESTS ARE USUALLY PERFORMED ON SAMPLES OF GENERALLY NON-COllESIVE SOILS, ALTilOUGli Tile TEST PROCEDURE IS APPLICABLE TO CollESIVE SOILS IF A SUFFICIENTLY SLOT TEST RATE IS USED.
m y
AN ALTERNATE MEMS OF OBTAINING Tile DATA RESULTING FROM Tile DRAINED TEST IS TO PER.
k' PRESSURES. TIIE DIFFERENCES BETTEEN Tile TOTAL STRESSES AND Tile PORE TATER PRESSURES m
FORM AN UNDRAINED TEUT IN WillCll SPECIAL EQUIPMENT IS USED TO MEASURE Ti!E PORE TATER 3
MEASURED ARE TIIE INTERGRANULAR STRESSES.
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PLATE 18-40