ML19309B455

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Confirms Recommendation Re Addl Subsurface Investigations. Three Large Diameter Borings Down to Base & Below Lowest Shear at Reactor at Fence Uphill & at Fence Downhill from Reactor Should Provide Required Info
ML19309B455
Person / Time
Site: Plum Brook File:National Aeronautics and Space Administration icon.png
Issue date: 12/14/1979
From: Philbrick S
PHILBRICK, S.S.
To: Igne E
Advisory Committee on Reactor Safeguards
References
ACRS-CT-1219, NUDOCS 8004040167
Download: ML19309B455 (1)


Text

SHAILER S. PHILBRICK c

CONSULTING ENGINEERING GEOLOGIST ITHACA. N. Y.1485o 337 TEAAS L.AN E 607 257 1957 16 December 1979 Ol87Rl807te ye ACR8 MEMans i

Mr. Elpido Igne Advisory Committee on Reactor Safeguards-H 5t.

uco 1819/9 Nuclear Regulatory Commission

'iashington, D.C. 20555 tblW" '

Dear Els This letter confirms my recommendation of today concerning additional subsurface investigations at the General Electric Cest Reactor near Pleasanton, California.

1.arge diameter borines numbers 3H-1, EH-2 and EH-3 are located about 3400 feet to the east of the GEC?.. They are informative of subsurface conditions at their own locations but they do provide conclusive information on conditions in the immediate not vicinity of the 3EOh.

There is some uncertainty about the presence of shears beneath the GETR. It is desirable to know whether shears are present and at what depth or depths. Similarly it is desirable to know the configuration of the shears, i.e. their locations in plan and profile up hilland down hill from the GETR. I have not found such info nation in the material presented at the 3an Francisco meeting in mid Govember or furnished r.e by Li by letter dated 21 November, copy of which was sent to you.

Che rossibility of isolating the foundation of the GET'J from the active side of the shears,i.e. the thrust side of a fault or the up hill side of a landslide, depends upon several factors the first of v:hich is the location of the shears in plan and profile. Hence my interest in determinir4 these data on the shears.

I would expect that three large diameter borings down to the base and a few feet below the lowest shear would provide the required infornation. They might be located approximately as follov.c:

a. At the GETR
b. A t the rence directly up hill from the GETI.
c. At the fence directly down hill from the OE03 Sin rel yo.

.2 hailer 3. Fh Ibrick y