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July 23, 1963 J
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- File h$N From R. H. Wilcox, Assistant to Exec. Secretary l
Subject:
DIAR MEITING WITH PACIFIC GAS & ELECTRIC ON JULY 2,1963, q
CONCERNING BOEGA FM SEIBMIC PROBLD48
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'Ihe purpore of this meeting was to discuss earthquake problems connected i
vith proposed construction end operation of the Bodega Bay rce.ctor. ACR$
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- nembers were invited to atter.l. A prel.iminary meeting involving DIAR, its j,
consultants, and ACRS was held at the Soliday Inn - West, Chicago, niinois l
from 9-11 P.M. on July 1, 1963 The entire group then met with PG&E and i l
[f-its consultants at the AEC-Chicago operations Office on July 2,1963 t'ros.
a-9 A.M. until about 3 P.N.
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Attendees for beth sessions:,
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AEC - DIAR r
H. J. C. Koute
- 1. R. Osborn E. O. Cace,
ii C. R. W1111ame R. H. Bryan
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D. A. Rogers F. N. Watson R. C. Stratton J. F. Newell R., H. Wilcox, Staff U. B. Geological Survey
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j g 2 - Co=pliar.:e A. Cleboch I
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R..f. Engelken DIAR Com ultants L". Cpencer y
N. M. Newmark, U. of Illinoist F. 3:umann, U. of Washington (toeritus)
AEC - 000 R. A. Williamson, Holmes & Earver W
- 0. F. Hadlock j
AEC-REGULATI_0N
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w C. K. Beck I
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M. H. Mann
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. Attendees for July 2 session only:
PG&E PG&E Consultants
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R. D. Darragh, Dames & Moore C. C. Whelritel G. W. Housner, Calif. Inst.'of Tech.
V R. V. ' Betthg,er F. F. Hautz D. Tocher, U. of California W. L. Quaide, Consultant P. A. Crane 4
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JULY 1 MEETING I
The July 1 meeting was opened by E. G. Case who indicated that he hoped to reach agreement among DIAR and its consultants on earthquake design
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Pj factors; then to explore whether there was any difference in such fcetors
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betveen DI&R ard the applicant.
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- p. t d-3 D aft reports of Ne'imark, Netmnn, and Williamson were handed out for Ld discussion purposes. It was stated that Dr. Ne'n=nn's conclusions could l
serve as the basis for the design report, although there was to be some JJ simplification of Neimnn's report.
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Dr. Newmark discussed the effects of earthquakes on structures in terms of acceleration end displacement " response spectra". He noted that there are records available of 19 strong motion earthquakes. Using the El Centro 3
r-earthquake as a base, he stated that a quake on the order of twice the peak g:
velocity and acceleration of this one is likely once in 50 years.
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A Cen',rohadapeakvelocityof14in./seeandaccelerationof033 gas nasaoured 4-5 miles from the fault. The epicenter was 20 miles below the
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surface.) Thus the "mavinnna credible earthquake" might cause 30 in/see velocities 3/h g accelerations, and 5-10 ft. displacements, the latter E'd occurring in steps. Displacements in California are usually horizontal.
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IJ Dr.Nevmarkexprinsedconcernoverhighfrequency(5-10eps) structures which he feels should be desir.;ned to 50% higher accelerations than now
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conte:uplated. The choice of demping factors takes a great deal of.judg.
F ment. Newmark believes that very stiff structures vill be worse on rock,
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since he feels there vill be little attenuation of such oscillations as compsred to soil.
a Dr. Newmark also cautioned that there would be greatest difficulty with
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elements which are attached to other elements which move. Thus a very elaborate dynamic analysis is needed.
Mr. Williamson noted that practically everything is in the high frequency The concern is therefore in the frequency range of greater than range.
2-3 eycles on roet.
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3 Newmark noted that care must be taken with regard to structures on differentfoundations(suchasreactorandturbine)connectedbyapipe.
The difference in displacements can a,gtoach.the sum of the, absolute values of the two displacements.
Drs. Neumann ani Newmark were in agreement that design abould be based on
- trice El Centro for soil with an addition on the high frequency side for rock.
7 Uncertainty was expressed as to what PG&E meant when it proposed to analyze for earthquakes five times as great as El Centro (whether velocity or
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energy).
It was agreed to explore this further the next day.
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Dr. Newmark' stated that vital switches could and should be overdesi ned C
L to withstand conservative earthquake grouni motions. (Dr. Bryan had cited I
4 mercury evitches 'as an example of a non-structural item which would have r.
to be considered.) '!bere was some discussion of other earthquakes., in -
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cluding the 1906 San Francisco quake for which damage would iniics.te much M
higher forces. Greater than 1 g earthquakes may have occurred in other
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parts of the world. Newmarkindicatedthatverticalaccelerations1/2-2/3 of the horizontal should be provided for.
3 Dr. Beck stanmed up by stating that he vould suggest to Mr. Whelchel that discussions the next day center on:
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Characteristics of earthquakes.
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How earthquakes would be applied to the plant design.
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coupling effects; a list of structures; secondary effects.
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4 JULY 2 McETING Dr. Beck opened the meeting on July 2nd by stating three basic questions j
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to be discussed; j
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With work going ahead on the site itsel'f, a' brief i
statement of any quite recent information.
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An exploration of possibilities of what designs. should i
go in.
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What are the basic characteristics'of earthquakes?
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Rw bad an earthquake might happen, in terms of velocity, L..
deceleration, displacement.as functions of frequency.
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What methods does the coepany propose for cecondary l
Hg systems not part of or coupled to the basic structure?
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Assumptions, criteria, principles.
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Fellowing brief statements by Messrs. Whelchel and Mauts, Mr. Quaide j
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discussed the site geology. He has been following the excavation and p-;
mapping as it goes along. De quarts-diorite is exposed on the north face. Down to +5 ft., the current limit of ' excavation, there was nothirg which could be proved definitely as a displacement. Bere were two places j
g'a wherehehadtoexercisejudgment(interpretation)tomakethisstatement.
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Dr. Tocher indicated that the 1906 earthquake was the only recorded one y
of interest in this region.
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Mr. Quaide and Mr. Clebsch both indicated that age determinations of i
P fossil wood samples were in process.
[i Mr. Quaide noted that there are stratification planesj but no evidence-of displacement on the southwest face. He thinks these and organic rich areas are from an old bay.. He has found no indication of a fault across the head at Campbell Cove and no evidence of 1906 breakage.
j Dr. Housner next described the strainins which 1s occurring in California and which eventually leads to a stress failun, or earthquake. Se
$/18/40ElCentroearthquakeresultedinsurfaceslippageovera40-50 mile length. Maximum relative slip on the surface was 15 ft. He noted that the majority of all destructive earthquakes occur on other faults, but that the largest earthquakes are almost sure to occur on the San Aniress
.or one of its southerly extensions.
Se 1906 earthquake resulted in slippage about 250 miles in length sai with maximum relative displacement of 20 ft.
Bere was also a large earthquake in central California in 1857
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, Bousner indicated that the intensity of shaking depends both on the energy release and on how close one is to it.
Since ordinary seismologic instruments go off ocale'in a erste earth-quake, dependence must be placed on the 72 accelerometers which began to be used in 1933 for engineering measurements.
InMsgnitude(Richterscale),slightdamagebeginsat5 Se 1906' earth-7 quake was 8.2, the-1960 chilean earthquake was 8 5 and 600 miles long. E -
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Centro was 7 1.
Se Modified Mercalli scale is used as an estimate of ground shaking inten-sity at a particular point. Ground accelerations are recorded in order to R
obtain spectra intensity.
I Dr. Housner then distributed the first of a number of handout illustra-d tions.
(copies can be reproduced for anyone wishing a set of these.)
l Most instruments are in cities, and therefore on alluvium. Records of-p the 1906 earthqvake indicate that it lasted 30-50 seconds.
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In general, the earthquake motion starts at the epicenter and proceeds down the fault at a velocity no less than 2 miles per second. Bere was ocae discussion of the nature of action 1000 ft. instead of 4 miles from a slip.
p Ilo secondary breaks followed the El Centro earthquake, and Dr. Tocher stated that aftershocks rarely produce additional surface breaks. Dr.
g Bousner noted ht he had inaected the damage from the 1940 E Centro gp-earthquake, and noted that it indicated less intensity in W immediate vicinity of the fault than where measured at El Centro. Five miles from "b
the fault, houses were also undamaged.
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Dr. Housner proceeded to discuss how he arrived at design eriteria for the b.c Bodega Bay plant. Pbr an upper bound, he used the worst throw assuming theentire1906slipoccurredasastep(lubricatedslip). He also ande l-use of the shape of the accelerogram records of the El Centro earthquake.
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There was considerable discussion over difference in intensity on rock as Dr. Bousner 'ndicated' h t a point on the surface
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compared to alluvium.
i of alluvium would have an amplitude of motion at least~ twice (and some say four to five times) h t of h underlying rock. Dr. Housner anda-the s
following cosparison as being about h best one could make Earthquake Magnitude Material Epicentral Measured
-Distance Acceleration long BeacE 1933 6.2 A11uvita 17 miles 0.25 g Belena, Montana 1935 6.0 Rock k miles 0.12 g Dr. Newmark indicated that something had been learned about this from nuclear tests.
In asneral, Newmark thought that there would be larger accelerations, smaller displacements, and similar velocities'on rock as
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compared to alluvium. Reference was unde to a Ims Angeles earthquake j
in which the dispiceenent on alluvia was three times that on granite.
At El Centro, this ratio was thought to be 8 to 1.
q Upon questioning by Dr. Kouts, Dr. Housner admitted that accelerations near the epicenter of the El Centro earthquake might have both larger _than were measured. Housner also agreed h t 1.4 times El Centro was a reason-able upper bound. Proceeding thence.to Bodega Bay, and because the plant would be located on rock, Housner specified 20% g as the maximum accelers-tion, and a spectrum similar to El Osntro,but correspondingly reduced.
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Damage information in the Bodega Bay region was next discussed. Deange I
was very much vorse on soft than on hard ground, but this was at least in part due to poorer foundations. Dr. Tocher reiterated that movements vest of the Sierra Nevada have been horizontal, not vertical.
M=.ny geologists
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feel that this is borne out by the long term geologic reco <.
i 1be meeting recessed fc; tunch at 11:40 A.M. and resumed at 12:40 P.M.
Pi-Discussion of design criteria continusd. Dr. Housner quoted from a paper r,.;
.to be given the next week by W. K. Cloud, Seimnological Field Survey Chief, l
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at a meeting in Chile. For greater than 71 angnitude earthquakes. Cloud recomm M a 0 50 g for maximum acceleration and 60 seconds for duration as
'j engineering numbers. Similar numbers are being used in the design of a water project along the fault, which crosses it in three places. In this qy case, the 0 50 g number was selected by a four man board, consisting of g
Benzoff, Seed, Whitman, and Housnar.
I Housner stamarized his design recommendations for the B)dega plant as:
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Ground motion equivalent to El Centro (33% g).
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Average spectrum for the two components measured at El Onntro.
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Use allowable stresses in the uniform building code without the1/3rdincrease.
y Various Bodega structures were next discussed. The reactor building was j
stated to have a 0.1 second natural period, and in general, major structures
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presented no problem. Motion of components should be based on El Centro or on calculated motion of major structures to which these were attached.
H Verticalaction2/3ofhorizontalshouldbespecified. on daseing, Housner wouldnowrecommend12%at0 period,decreasingasymptotically to75%
with increasing period.
(3his is greater than the 7 5% he previously recco-mended bees.use the soil is more dense than previously contemplated.
As for the factor of 5 analysis proposed by PG&E, Bousner said that things shouldn't fall down in an earthquake five times as_ intense. When asked about control rods, however, Bousner said he couldn't give a categoric answer for all equijanent. He felt the factor of five would provide a margin J
for stronger motion and defects in materials. He meant five times the E1-Centro acceleration spectrus (25 times the energy).
- Messrs. Whelchel and Housner thought that this analysis vould substantiate that nothing would fall or be overtrained if there were a 1906 quake every.
day.
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Dr. Beck suggested that one must loak at penetrations,. rods / etc. in a piece-by-piece analysis to meet the umurinrum credible earthquake.. Dr.
Ecuts suggested that this be done on those things which must be relied upon for ultimate safety. ' Mr. Whelchel stated that he coult not answer for all of these at this time.
'l At the low period (high frequency) end of the spectrum (less than 0.2 seconds), Housner indicated he would " fair in"'s curve. Mr. Mautz indicated that, instead of the Class I, II andLIII structuren previously e
planned, PG&E was now thinking of only two classes, " critical" and "all others". In the " critical" category would be the stesa loop and feed-water piping, containment, stack, turbine-generator foundation, and tanks j
and lines storing and feeding water. S e emergency water reservoir vill be located on' elevated ground at a spot yet to be specified.
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.;j In reply to a question by Dr. Bryan as to design criteria for critical
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cocoonents other than "atructures", Dr. Housner and Mr. Whelchel indi-ll
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cated that this needed a detailed look. S e question of future schedule 7
mj was discussed briefly, then Dr. Beck suggested a caucus.
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CAUCUS (PG&E AND ITS CONSULTANTS NOT PRESEFF)
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Dr. Nevasrk felt that twice El Centro should be the design earthquake.
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R us, the design should provide for:
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.23 g with allowable stresses g
33 gat 1-1/3verkingstresses, 97 or
.k5 g at the yield point Dr. Newmark said that some say.you should takg the RMS or envelope of the N-8 and E-V El Centro records, thus arrivirg at.45 g for this earthquake.
q Dr. Beck mentioned that a provisional construction permit could reserve c,
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on such items, however, others, including Dr. h, urged that an attempt
[.i be made to reach agreement.
Dr. Kouts pointed out that the applicant was in fact backing down from previous commitments, and had established no basis for so doing.
a Dr. Newmark restated that he vould reccamend.66 g (twice El Centro) with appropriate damping.
PACIFIC GAS & EIECTRIC 00.
Dr. Beck. pointed to the discrepancy in what was said in the meeting and previous submittals, as between the N-S El Centro and' allowable stress intheuniformbuildingcode,033g(with1/3 increase)and.45 gat-yield.
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Bousner stated that his recommendation was the N-8 El Centro with the anovable stress in the building code (1/3 over normal); thus he had recomended.45 g at yield.
It developed that Housner bad, intended
- i the average El Centro spectrum to go with the g values which appear in the PG&E submittals.
(The average El Centro with allownble stresses is I
thus equivalent to the N-S El Centro with allowable stresses increased by1/3.)
M Dr. Kouts pointed out that this was not the original proposal, and Dr.
Newmark inquired about the worst El Centro. Dr. Housner noted that I
motions were statistical, but didn't seem to vary much as a function of direction.
A design specification of 0.66 g would not effect the bottom 'of the '
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structure, but would effect the vans of the refueling building.
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Dr. Eousner defended his criteria as conservative. He repeated that
?-l many seismologists use a factor greater than 2 from anuvium to rock.
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He argued that au recorded quakes fonov the same pattern. Thus,2/3 W
of the El Centro ground motion is the most he expects at Bodega, the F
other1/3issafety.
If.45 g is exceeded, he would expect a hairline
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crack.
Mr. Watson inquired into intensities ()t>dified Mercalli.seale). Housner Tocher s' d Housner noted that II was' indicated that El Centro was a II.
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the minimm if a ground crack was observed, thus they discounted the p
value of such observations.
Dr. Beck indicated that the matter deserved careful thought. He suggested 1
a specification of 0 5 g without yielding for structures, and 0,66 g for y
control rods, etc. to remain in operable condition.
(or.33gwitha 3
factor of safety of 2 against yielding).
Dr. Housner thought this was
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7 p.u not unreasonable.
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Dr. Kouts noted that the only question then would be the' refueling i
building. Dr. Housner felt this could be handled, possibly through the I
analysis at a factor of five times design.
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Dr. Housner noted that PG&E vould' vant to check with its vendors, however.
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Mr. Case suggested it might be better to have criteria, then grant ex-ceptions in particular situations.
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