ML19322E735
| ML19322E735 | |
| Person / Time | |
|---|---|
| Site: | Vallecitos File:GEH Hitachi icon.png |
| Issue date: | 03/31/1980 |
| From: | Darmitzel R GENERAL ELECTRIC CO. |
| To: | Eisenhut D Office of Nuclear Reactor Regulation |
| References | |
| NUDOCS 8004020185 | |
| Download: ML19322E735 (5) | |
Text
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G E N E R A L Oh E LE CTRIC
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ENGINEERING OENERAL ELECTRIC COMPANY P.O. BOX 460. PLEAsANTON, CALIFORNIA 94566 DIVISION March 31,1980 Mr. Darrell G. Eisenhut, Acting Director Division of Operating Reactors Office of Nuclear Reactor Regulations U.S. Nuclear Regulatory Commission Washington, D. C.
20555
Dear Mr. Eisenhut:
SUBJECT:
Dip Angle for General Electric Test Reactor (GETR) Site Shears The measurements taken to determine the angle of dip in the trenches at the GETR site were reviewed by Earth Sciences Associates. The results, which are attached, show that the dip angle was 45 degrees or less on all shears observed at the GETR site. We recommend that if surface offset is to be considered in the structural analyses that dip angles ranging between 10 degrees to 30 degrees be used.
Very truly yours, bA'7 ! i'
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Irradiation Processing Operation
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Nuclear Engineering Division
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AFFIRMATION The General Electric Company hereby submits the attached letter, subject
" Dip Angle for General Electric Test Reactor (GETR) Site Shears".
To the best of my knowledge and belief, the information contained therein is accurate.
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Submitted and sworn before me this 31st day of March 1980.
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, Notary Public in and for the County of
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Alameda, State of California.
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March 27,1980 1886 MEMORANDUM To:
Dwight L. Gilliland, cy ma a
Manager, Reactor Irradiation
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~a General Electric Company
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From:
Richard C. Harding, L
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Earth Sciences Associates
Subject:
Recommended Design Values for Dip Angle of Potential Surface Offsets at the GETR Site This memorandum is in response to questions regarding the angic of dip of shear surfaces Ahich would result from postulated thrust faulting at the GETR site.
Because regional tectonic stresses that govern the style and rate of displacement on faults in central California have remained relatively constant over at least the last few million years, it is reasonable to assume that future offsets within a fault zone will have a similar orientation to offsets that have occurred in the recent geologic past.
Existing sheus at the GETR site, upon which repeated movements have oc-curred, consistently exhibit low dip angles. Table 1, attached, is a list of attitudes measured on shear planes in the trenches. All of the shears exposed have dip angles (largest acute angle between the plane of shear and a horizontal plane) of 45 or less.
Of the measurements taken, 70 percent of the dips are 30 or less. The two main shears closest to the GETR (ll-1/B-3 and B-2) have dips ranging from 0 to 25.
From fault mechanics theory, it is known that shears develop at angles less than 45 (most commonly 30 ) with the greatest principal stress axis. Low angle thrust faults, such as the postulated Verona fault, develop when the greatest principal stress axis is horizontal, as occurs in regions of the earth's crust that are under compression.
Although the principal stress axes can have any orientation within the earth's crust, the low angle thrust shears at the GETR site indicate that in the recent geologic past the greatest principal stress axis within near surface materials at the site han been hori-zonte There is no reason to expect that
- is stress orientation has changed since the las offset occurred or will change in the n tr future.
Thus, it can be assumed that postulated future offsets at the GETR site will 1.
Earth Sciences Associates
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occur on low angle shears with dips less than 45. Although it is highly unlikely, based on the geologic record and on probability analyses, that future offsets will occur in the GETH foundation soils, if surface offsets are considered in structural analyses, I would recommend that dip angles in the range of 10 to 30 be used.
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3 Avg. Value of Trench /
Shear Plane Striations /Crooves Complement of Complement of Boring Station No.(1)
Strike Dip Trend Plunge (2)
Pitch Angle (3)
Pitch Angle B-1 0+40 N32 W 9N (none observed in field)
B-2 0+56 N35 W 25 NE N42 E 24
+12
+12*
B-3 0+10 N60 W 20 NE N38 E
' 20
-8
-24 0
0+27 N65 W
,15 NE N55 E 13
-39 11 0 +91(E)
N85 W 30 N N30 E 25 8)
-22
-24 0+76(W)
EW 35 N N35 E 35 0)
-39 U
0+85(W)
EW 25 N N35 E 25
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-g2" 0+94(W)
N55 W 15 N N35 E 10
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0 0+8G(W)
N70 W 30 N N40 E 25
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-18 b
0 0
T-1 125-152 N51 W(avg) 14 N(avg)
N15 E(avg)
(12 avg)
+23
+23 U
0 0
T-2 112(')
NSS W 22 N N37 E 22
-2
+1 120(I)
N85 W 25 N N32 E 25 22 )
-25 120(1)
N25 W 15 N N60 E 21 15 9
+5 2 6 (11)
N75 W 35 N N50 E (30 )
-30 2G(II)
NIS W 42 NE N20 E (27 )
47 2G(II)
NIS W
'30 N N20 E (27 )
51 U
20(11)
N10 W 35 N N4 g (10 )
73 U
2 2 (111)
N75 W 33 NE N45 E (29 )
-26 2 8 (111)
NGO W 30 NE N55 E (27 )
-22 2 8 (111)
N80 W 45 NE N55 E (35 )
-35" Notes:
(1) Roman numerals and E(east), W(west) in parentheses are keyed to walls logged in Trenches T-2 and II.
(2) Values of plunge in parentheses were calculated from shear plane attitude and trend of striations / grooves.
(3) + values indicate that the strike-slip component of slip is right-lateral.
- values indicate that the strike-slip component of slip is left-lateral.