ML20197B048

Comments on 780824 Meeting at Facility.Believes Verona Fault Presents No Threat to Facility.Strong Earthquake Possible

ML20197B048
Person / Time
Site:	Vallecitos File:GEH Hitachi icon.png
Issue date:	08/25/1978
From:	Page B STANFORD UNIV., STANFORD, CA
To:	Kerr W, Seiss C Advisory Committee on Reactor Safeguards
References
ACRS-CT-1037, NUDOCS 7811010220
Download: ML20197B048 (1)

Text

^IsVISCP.ROMrm C STANFORD UNIVERSITY ,1 tic 1n2 sancou:m, u.a w STANFORD. CALIFORNIA 9.u0; {

AUG 2919'/8 IMI.N! OFC[ OLOGY I l of f anh 5cance.

25 Au@ pt 19,78 ,9 , . . . .

I*'38'n b Q'g$.Q.Ig.lb e t -I Drs. Chester P. Siess and William Kerr Re: Generni E1cetric Advisory Committee on Reactor Safeguards Test. Henctor Dr. Richord Savio, ACRS Staff

Dear Sirs:

/00AL. lCh/'W I attended the inceting of 24 August 1978 at the Gl?fR nuclear pl ant near Pleasanton, Calif ornia. NRC staff scientists and GE personnel held a f ruit ful discussion of the company's t entative plan for determining the presence or absence of faults near the plant and for obtaining further information regarding Inrge landslides which might a.f fect the safety of the installation.

The four or five trenches proposed by GE pro well advised ond appent to be locnted as advantageously es possibic. A seismic reficction profile is also being considered, at the suggest ion of R. E. Jackson of the NRC Staff, although technien1 difficulties ere likely. I favor the proposed program os the one most likely to resolve the question of poss i bl e

. sur f ace f aulting near the plant structures. The trenching may not succeed in resolving t he problems, but it appears to be the most promising approach.

Pending the proposed trenching, my provisionni opinions as to enpable f aul ts and carthqunkes in the oren oro os follows: (1) I now think (contrary to an earlier impression) tha t the Verona fault mapped in the vicinity by C. A. Un11 mny, in fact, exist. (2) If this inu11 is real, it is most likely a north-dipping thrust f aul t near the base of the hills '

overlooking the plant, but its near-surface trace is well beneath the ext ensive landsli de compl ex which const i tutes mos t of the lower port of the hil l si de. This postuinted locat ion would probably make the f aul t innecessibic to the proposed t renches nenrest the pl ant, but i t should be intersected by propor.cd Trench A some distance to the c'ast, 11 it exists. (3) If the Verono fault lies benoot h the landslide complex north of the plant. I do not think it is t. t hrea t in terms of possible disruption of the plant structures.

l (4) If the Verona inult exists, it is not a major feature which could cause great enrthquakes, so the Calaveras f ault (2 km f rom t he pl ent) remains es the potentini source of t he SSE.

A likel y resul t of the trenching will be the disclosure of one or severn1 mini-f aults with displacements ccosured in cent imeters or o few meters. These are commonpince in the western st ntes, nnd unless closely spaced or genetically related to a nentby coppble f ou11, ' hey ere insignificant.

If these features are found in trenches alongside the plont, they will j arouse fervent arguments.

On the whol e, there is a fair chance thet the plant can be shown to be safe from surface faulting. As o11 parties ren11ze there remains the possibility of n strong corthqunke.

Sincerel y, f lN&ff 0e h]- s llenjamin M. Poge ACRS Consultant