ML20235X694
| ML20235X694 | |
| Person / Time | |
|---|---|
| Site: | 05000000, San Onofre |
| Issue date: | 07/09/1970 |
| From: | Newmark N ILLINOIS, UNIV. OF, URBANA, IL |
| To: | Case E US ATOMIC ENERGY COMMISSION (AEC) |
| Shared Package | |
| ML20235X376 | List:
|
| References | |
| FOIA-87-462 NUDOCS 8710200082 | |
| Download: ML20235X694 (5) | |
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' N A T H A N M. NEWMARK CONSULTING ENGINEERING SERVICES 1114 CIVIL ENGINEERING BUILDING 1
URBANA, ILLINOIS 61801./p%
.9 July 1970
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ld p% l 4 fI; Mr. Edson G. Case, Of rector I
Division of Reactor Standards i
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U.S. Atomic Energy Comnission
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Washington, D.C.
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Contract No. AT(49-5)-2667 O
San Onofre Nuclear Generating Station Units 2 and 3
. Southern Illinois Edison Company and San Diego Gas and Electric Company AEC Dockets No. 50-361 and 50-362 l
1
Dear Mr. Case:
Dr. W. J. Hall and I have reviewed the Preliminary Safety Analysis Report for the San Onofre Nuclear Generating Station Units 1 and 2, and call attention below to certain items for which additional Information is required.
In reviewing the PSAR lt is noted that the appilcant has recommended that the seismic design be carried out for a Design Basis Earthquake characterized by a maximum ground acceleration of 0.50g to insure. safe shutdown and containment, j
and that the plant be analyzed for an Operating Basis Earthquake of 0.259 maximum horizontal ground acceleration.
It is our understanding that these seismic design l
levels are currently under review by representatives of the USGS and'the USCf,GS l
and that a decision as to the acceptability of the applicant's criteria will be l
forthcoming as a result of Joint meetings between the aforementioned representatives, l
AEC personnel, and ourselves at a later time.
No further comment on this aspect of the criteria is made In this letter.
As a result of our review of the PSAR we should like additional Information from the applicant on the following items:
1 1.
It is Indicated on page 2.9-6 of the PSAR that major structures will be founded in the San Mateo Formation.
Furthermore, slightly later It is Indicated that it is planned to make deep excavations for Units 2 and 3, with the slopes
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't outside of the switchyard cut at an angle of one-half horizontal to 1 vertical with a 15 f t benchmark at the contact between the terrace der,osits and the San Mateo sandstone, and for slopes below the switchyard the slope.s will be cut at an even flatter gradient to accommodate the Design Basis Earthquuko ioadings.
A summary of the stability analyses for the slopes is presented on page >II-18 of Appendix 2b and indicates that factors cf safety on the order of I to 1.2 exists f or slope angles of 20 degrees and 15 d<.grees, respectively, for seismic accelerations of 0.59 With this background, then, the applicant is reque.sted to explain in more detail the criteria that will be employed in selecting the actual slope angles for the cuts, and to indicate the basis for the margin of l
safety or factor of safety that is felt to be adequate.
In evaluating the margin of safety associated with the cuts it would be instructive to have an indication I
1 of. the magnitude of the estimated slippage that might take place f rom earthquake excitation. Also, the applicant should indicate whether the vertical earthquake effects were taken into account in assessing the slope stability.
The appitcant is also requested to indicate the proximity of the cuts to major structures or equipment, and Indicate the allowance that exists for slope slippage before critical damage would occur.
2.
The response on page 1.8-38 of the PSAR Indicates that the contain-j ment structure foundation will be located approximately 20 f t below the adjacent finished grade.
It is further indicated that the method selected for handling thv soil-structure interaction will be based upon the referenced material in Appendix B, Section B.1 and that a summary of the criteria will be submitted af ter, more detailed design is undertaken. We reconmend that an arrangement for revliw of these criteria and design techniques be made cs soon as they become available.
3 The smoothed response spectra for the San Onof re Nuclear Generating Station Units 2 and 3 are presented in Figs. 2.10-1 and 2.10-2 and in Figs. B2-1
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i and B.2-2.
In each case the spectra are those for the Operating Basis Earthquake i
and the Design Basis Earthquake, respectively.
It should be noted, however, that I
there evidently is a mislabeling of the caption on Figs 2.10-2; this figure 4
evidently should be labeled " Design Basis Earthquake,
1 lt Othough no descriptico is given in the text of the PSAR, It appears that the Design Basis Earthquake spectra may be patterned af ter some specific unnamed l
ea rt hquake.
For frequencies greater than 6 cycles per second, the spectra are significantly below even the TID 7024 spectra which we considered to be absolute i
l lower-bounds to acceptable spectra.
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The Operating Basis Earthquake spectra appear to be more llke those of the TID 7024 spectra but even in this case there seems to be less ampilf fed response in some of the frequency ranges, es for example betwen 10 and 40 cycles per second.
1 It appears that the spectra also may be deficient in the midf requency range as l
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ccmpared to the TID spectra.
l Also, the spectra for the OBE and DBE are quite dif ferent in shape, l
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t ha t is they are not scaled one f rom the other; on explanation of,this difference
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i is desired, j
In sumary, as presented, the Design Basis Earthquake spectra are
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l definitely deficient in certain frequency domains.
In order to provide a basis i
f or further evaluation of the adequacy of the spectra, the applicant is requested 1
to describe in detall the basis of the development of the spectra and the reasoning
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as to why these are believed to be applicable and adequate.
l 4.
In the response presented on page 1.8-51 of the PSAR, the following is indicated:
"T.Se vertical ground acceleration is two-thirds the horizontal l
acceleration. ;For periods greater than I sec. the value of three-quarters I
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horizontal acceleration is used." Gravity coefficients similarly scaled are i
presented in Section B.2 3.1.1.1 and B.2 3.1.1.2 in Appendi A B to the PSAR.
The l
l manner in which these vertical seismic coefficients are presented suggests that I
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il the design for vert
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. coefficient.
The a:plicant is/ requested to Indicats in some detall the prectsc-l t
n manner in which the verticeII ex' itation will be handled in the design and ' analysis c
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L procedures, namely whether It wM1 Invelve the use' of a con'stant acceleration l
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coefficient, acceleration corresponding to amplif ted motions, or oue other method.
S.
ihe rethods of dynamic analysis to be,gmployed for the containment
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v structure, reacter coolant system, reactor vessel ' Internals, piping, 'etc., are described at varlots places In the PSAR, but ' in the greatest detall In Appendf x' 8 of the PSAR.
The descriptions given are'quite ' general.and bithough the methods 1
descriteb appear ge erally satisfactory, there is little.on which to base, Judgment'
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as tc the technical adequacy of the procedures to be empluyed.
It would be helpful o<
If the applicant coald supply a table or chart for each major, item or group of itens.
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of Class I structures and equipme.t, as well as, Class II structures and equipment, to show the folicio g :
themethodofanalysistobe sed (whether response spectra, J
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l time history, peak seismic ccof fijlent f rom response shectra, or other methods); the I
appropriate dampine coefficient); stress or deformation levels applicable; margins I
I of safety for the c:rnbined loading conditions considered, or a. discussion which 1
would permit s ch ehaluation; the descrip, tion of the method by dhich shears, moments, and stresses and/or deflections and accelerations areEcomputed 'for. each mode, as,
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well as for combined total responsel ud any specla'jcomments ot/ explanations neces/ary such as, #or examole, s'pecific procedur es, / tused in : defining' the re i
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spectrum for J,tems supportet at different levels.
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The prese-tution should include considerat on,of'both 't'r,e vertical and l
horizontal excitatten, the method used for combining bartzontal excitatt'onL in the 1
9 and for combining' horizontal, torsional and various directions, if this is donen
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vertical excitatto. Also, it shdfolindicate the methkby which differential s
s-floor displacements or other differ,ential displacements will be handled for piping
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connected at various floors, to ekulpment and floors,8etc.
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5 A summary of this type would aid immeasurably In arriving at a basis for evaluation of the adequacy of the proposed design approach.
6.
The design of the liner plate anchor is discussed in Appendix SF.
With reference to Fig. I contained therein, It would appear that under some conditions the initial displacement of the liner might be radlally outward rather
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than radially inward as Indicated in the figura.
Accordingly, it would be Instructive to know the effect of a radially outward initial displacement of the par,el under thermal cycling liner behavior and the adequacy of the anchors to resist the forces arising from such displacement.
7.
The discussion of special procedures to be employed for seismic design of systems and equipment is presented in Section B.2 3.1.2.3.
As indicated, certain analytical approaches may be employed, or alternatively dynamic testing of prototypes of equipment may be substituted to insure functional integrity.
In this respect, the appIIcant should Indicate further the approach which is taken in the procurement of Class I equipment, controls and Items to insure that they will meet the selsmic design criteria.
For example, It would be Instructive to have a discussion of the approach followed in the case of items for which procurement specifications (which include selsmic criteria) are issued, and the subsequent evaluation of their adequacy thereaf ter.
Clarification of the approach adopted for all of the various types of critical systems and equipment of this type Is needed in assessing the margin of safety inherent in the design approach.
Respectfully subm!tted, N1 N. M. Newmark P9 cc:
W. J. Ha l l