ML20148T806

Comments on Tera Corp Rept Simulation of Earthquake Ground Motions. Rept Is a Breakthrough in Understanding Seismic Wave Propagation & Ground Motion Characteristics.Should Not Be Used to Provide Basic Plant Design Criteria

ML20148T806
Person / Time
Site:	San Onofre
Issue date:	10/05/1978
From:	Seed H AFFILIATION NOT ASSIGNED
To:	Wright R Advisory Committee on Reactor Safeguards
References
ACRS-CT-1062, NUDOCS 7812060086
Download: ML20148T806 (2)

Text

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Dear Mr. Uright,

I In response to your request I have reviewed the report pro-pared by Tera Carporation on " Simulation of I:arthquake Ground -{ Motions for San Onofre Nuclear Generating Station, Unit 1." { I .^ t In my opinion the research described in this report represents y a major contribution--in fact a break-through--in the scismological i field and has the potentici for providing a vastly improved under- [ vtanding of scisnic uave propagation and grour.d motion characteris- [ tics. Ilowever I do not think that the 1.heory has yet been developed to the extent required to provide basic design criteria for nuclear j[ power plants for the following reasons: { i

1. The analyses are neccusarily based on,a simp 1.4. fica geologic f profile which does not take into account either the geologic  !

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      -         discont.inuitien along the travel path of the scismic waves or                                     }

the non-31ncor characteristics of the soil layers near the { ground surface. Yncsc effects could considerably modify the { resul ts obtained by the type of analysis used in this study and j' would need to be considered before quantitative design data  ! could he developed. l

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2. I do not think that the 131uutrative examp3cs presented in the j report provide a suf ficient degree of agreement between  !

predicted and recorded motion characteristics to justify any j reliance being placed on the usefulness of motions predicted by  : thin approach for the San Onofre plant at this time. {

   - Perhaps r:cmo years down the road the analysis procedure will bc                                              ;

sufficiently improved to permit such a ucc -but I do not think it in good enough at t.his stage. , f 9 78120G0086 .

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I do not want the above remarks to detract in any way from the  :: I consider it a great accomplish- I,, accomplinhments of the Tora work. C mont that in spite- of the complexity of the prob 1 cms involved, the Tera analysis provides results as well as it does. Such results can f be used I believe to provido useful guides on the general naturc ['

            -of scicmic waves at a site but in my opinion, the procedures are not                                                   E
             ;sufficiently refined or verified at this stage to be accepted                                     as a                EI
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basis for the design of nucicar power plants. F t Very truly yours, ki e 0 .5% M 5 H. Bolton Scob' 'h [r, HUS/nh . hl r ki t?

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