ML20234C838
Text
{{#Wiki_filter:. , , . .. . ,. .
/
( .. .
. b '
b
-DRAFT OF
/f 1 .
REPORT: TO . AEC REGUIATORY STAFF ' A SEISMIC EFFECTS ON BODEGA BAY REACTOR
- p BY- ,
N. M. ENMARK . 4 22 AUGIET 1964- ii yi
. .g INTRODUOTICH -
,, $2
+s facility '-I l
This report concerns the ability of the reactor / proposed by the I fg m Pacific Gas and Electric Company to resist an earthquake opposite Bodega g;, postulated pq l Head having the marinnan effects assestbet by the U. S. Geologica1' Survey and ' b-Q f the U. S. Coast and Geodetic Survey. . Reference is made in.this report to f the application by [. 4 MlHiMBastmoco8 cot the Pacific Gas and Electric Company conderning' this ~I Particularly Amendment No. 8. , M reactor,/ 9-- ^ - _ _ _ = M -- - -- -d - 2_=-"= 7 -
^ -
- 2*'i F-
- 'c {
e_. T -1 _- i-- _ _ . _ _ f- _-- _ _ - _- - ' - - - - n- = --- -; - ' '-- Fr = --^- I ~._T i H. The general description of the ==har="Tn==AhA= earthquake / involves a Postulated l:- 3 i i pattern of ground motions similar to that recorded by the Coast and Q Geodetic Survey in the El Centro Earthquake of May 18,19ho, but with approximately twice the intensity, corresponding to a maximum acceleration of two-thirds gravity, a maximum velocity of 2 5 ft/sec., and a maxianna ground displacement of 3 feet, but with ocessional' and intermittent pulses of acceleration up to 1.0 times the acceleration of gravity. The
.$oV 1~
response spectr.ua for the earthquake without the acceleration pulse up
, et L. 9709210433.855217 1 .
q.. PDR FDIA % FIRESTOO5-665 PDR L < !f'
- g -. -- .s.. +. 4 g. -. ...# m ew, -. see emey m---
. amen.***** ** * * -
4
0
. 2 to 1.0g will be similar to that of the El Centro EartEquake. With the additional acceleraticos, the high frequency part cf the spectrum will be increased somewhat.
In addition, the structures am ecosidered to be' subjected to - , shear . s. simultaneous yeuxusa displacensuts ranging up to 3 feet, along samsta lines - ( extending under the containment structure or other parts of the plant, with F--- motio:2s in either horizontal or vertical directions along the fault. It
.. -g is assumed a2mo that after-shocks of intensity equal to the E1' Centro quake
-4 might be suffered before remadial action could be taken. f.1 Under these conditions, and with the design considerations described d
n4 and'in previous application amendments 6~.f in Amendment No. 8[ it is agr conclusion, after study of the matter, that the [% 1 . structural integrity and leak tightness of the containment building can be @ ! Postulated. m.
" ^ 2 $2 = - - - ' * - - - '= 4 v.aintained under the conditions " l ' -%- -- " -
] '
"-2_ _ _ _il _ _ _ _ .- _" _ l : __"_ l _ ^---- _
^
2,__..".__^_l____- '____-- -_
]
l moeosppstostabanos However, certain' precautions that must be considered in , .i D . .? the design are outlined more fully herein. ., h h r ".- ' 1--- I,'O 4..<
. - - - -g----____----------_----____--_- - _ - - - ____- - - _ -
g
~ . -M Similarly, the ability to shut down the reactor and maintain it in M the shut-down condition would not be impaired, provide'd that 'the intensities j '
' I postulated.
of motion and the magnitudes of fault slip do not exceed those wi==nehhma.- U Again, certain precautions ,am required as described more fully below.
'Ibe primary system, being contained in the massive reactor containment structure, would rsmain intact up to fault movements not exceeding 3 feet, and under earthquake motions as described above, provided that the piping system carrying the main steam lines from the dry well to the turbine.
s s a 1
. * - - +
. . - - . ~ . - ,,
* +
--) ~
inlet-is made sufficiently flexible to accomanodate 'a ' relative movement 'of -
. ~
3 feet without failure, and at the same tims is danped to reduce its #namic response to earthquake oscillations. Further comment cm this matter is - made below.
'Jhe supply of power to the facility..from power lines crossing the major fault, might be interrupted, although the probability of. such -
[ , interruption'is probably fairly low. In the event of such interruption, auxiliary power supplies are required. The description of these auxiliary . [U k .. :
,, power provisions seems adequate. , !.:{j s :.t In general, the provisions for meeting the' various requirements _ are %
y based on methods for which some background of experience is available, or g-h on minor modifications of such methods, which in the light of ana3ysis and Mj study appear to be reasonably adequate. r;d' g The earthquake motions, including acceleration and velocity 'as well " as displacement, appear to be 2 to 3 times more intense than any that have ,
,.]
;.h been recorded in the United States, and probably about twice as intense 2
W
.g.1 as those experienced anywhere else in the world in recent years for which Y M
we have fairly good records. Nevertheless, it appears that the design
~
objectives can be accomplished. , J. A more detailed discussion of the various points described in . Amendment No. 8 is ' contained in the following material. In additien, L consideration is given to several points not specifically discussed in the anendment. l y ISOLATION OF SHOCK FROM FAULTING BY MEANS OF UAND LAYER In the study of this problem I have had the benefit of a review of the current state of knowledge of this aspect of the problem made by Mr. R. A. Williamsch of Holmec and Narverp/a consultant The statements to made the AEC staff. herein o j e
. . . w .a . , . .
> - w n
- - a v;~ t
'- ~
. is .
. ~
- reflect in general his studies, as interpreted by me, and'the final con- >
clusicas are based o'n my views as well as his. . - The properties of sand under static loading have been studied for many years and am well understood. The frictional resistance in natural beds: i of sand has been measured and compared with bekaYior of such beds under s various conditicas. Within acent years #namic tests of the behavior . - i i of sand have been made by Dr. R. V. ' Whitman of MIT Dr. H. B. Seed of the University of California at Berkeley, and by others. The results of these
.- = ;
u.:,_a . tests, and of the engineering experience for many years, indicate that the NI a l frictional resistance of send, as measund by the angle of internal r j friction, changes very little for velocities of the order of 2 ft/see., and Eg the change is noti gnster than about 20% for velocities slightly greater
.e !
than 3 ft/sec. The coefficient of friction, as measured by the tangent of l (( the angle of internal friction, corresponds to values ranging from about 'O y m-0 5 or slightly greater up to about 0 9, and in general there appears to -
.c d be a slight decrease in tne coefficient of friction for high contact y pressures er for high loadings. -
;.3 '
~.-ij -;
The constancy of the angle of internal friction is dependent on the ' relative density of the sand. If it is in a condition corresponding to b a density of the order of 90 to 95%.of its maximum possible density, the 1, friction angle does not increase with motion. For. very low mistive densities, or for loosely packed sand, the friction angle of dry sand 1. will increase with leae.ng. On the other hand, this increase in friction ' t-angle of loosely packed sand is accompanied by a reduction in volume, and this reduction in volume, under conditicas of saturation, corresponds to ' a great increase in the pmssure carried by the inter-granular water. .' ' 1 I i' i
;I
. - . _ - . - . _ - - - ~ - - - -
~ 'l_
~~}
l.
, , , b .
L . L
.5-This results in a temporarily decreased effective frictional resistance, and i'
therefore it is quite reasonable to expect that under the ceditions 'of deposition of the sand layer, the frictional re..sistance vill not effectively i be increased over the value correspeding to the density achieved in place-- l ment, over a long period of tims. However, after an ear +hquake has occurred,- i the conditions prior to the next earthquake vill have been slightly changed, - if the sand is in a very loose condition to begin with. Nevertheless ',a
; q change in density of the sand would not be expected to occur unless b.
relatively large motions take place. Consequent 2y, the structure should be g],38
.g.
j with the maximum effects postulated - ! able to resist very successfully a anime earthquake [ although there are p%s P:" M - possibilities of it not being able to react with full effsetiveness against of*5
}&;
a second major earthquake of the same intensity. Since this is a most q F .- unrealistic condition, however, it will not be considered further in this f; - report. _-d'
'Ihe skin friction angle between reistively smooth concrete and sand -
[{ rw in generally slightly less than the friction angle in t,he sand itself; y ,
- <.1 hence the resistance to sliding of a properly constructed structure on a gj ,
. a sand bed een be made as low as that which corresponds to a coefficient of $;
friction of the order of 0.6 to 0.8, and it can be expected with smus S--j' a
.a confidence that this coefficient of friction vill not' increase with tims [j provided that Cf the sand is clean and the water inundating it does not contada W
cementing compounds. Min'or earthquakes having accelerations less than that required to overcome the frictional resistance would not affect the behavior of the sand at all. - L
- s. t 4-R 4{1
,i.:
. .~ _ . _ _ . . _ _ _ _ , . . . _
. (
DESIGN OF PIPING._ ETC. . TO ACCOMMODATE RELATIVE MOVEMENT AND VIBRATORI EFFECTS The amendment indicates that adequate anchors and bracing vill be pro-vided to prevent large relative motions of the piping connecting the dry well to the containment shell. Beyond the anchor at the containment shell, and extending to the anchor near the turbine generator foundation, the piping vill be subject to the differential fault motions ranging up to or _
! I as much as three feet, as well as the vibratory, motions induced by the l assumed -I
~
earthquake accelerations. Since the time sequence of'the/ faulting and the , . '. 5 i oscillation is entirely a random matter, both of the effects must be con- .w-e PC:4 pg sidered as occurring at any time, even simultaneously., , i &, The precise strains in the pipe due to relative motions or due to @m : '; l earthquake vibrations are functionn of the length of the pipe runs in the ?d various directions and the method of anchoring. The curvatures in the pipe, Y*b
-C.g )
.g i
~
and hence the maximum strains in it, due to a slow relative motion of the -
..[f .
ends of a pipe run, are primarily a function of the geometry of the system, * [i _s;-il . and are independent of the thickness of the pipe shell. The diameter of Ml the p!.pe and the length of the runs in the various directions, as well as the conditions at the support, namely whether these are fixed or hinged to )) provide rotation, are the primary influences affecting.the strains accompanying .); L' a given relative motion of the ends of the run. The maximum strain is in 4 I s. general of the order of k times the diameter of the pipe times the relative %j displacement divided by the square of the component of length of the run in the direction perpendicular to the displacement. This value of the i strain corresponds to a condition of fixity at the ends of thd run. If the ends are hinged, which is an almost extreme condition that can not be , obtained except with flexible connections, then the str,ains are reduced to possibly two-thirds as much as 'those corresponding to fixed ends. , i n i i
L L _7_
. O Therefore, the higher value will be used _in the estimates' made herein.'
Both the horizontal and vertical components of the pipe runs 'of the 20 inch main steam lines are appmzimately 80 feet.' Since'the pipe is 20 inches in diameter, the corresponding strain is approximately 0.003 in/in. This is about twice the strain at the yield point. ! Therefore, without '
\
flexible connections, the strain in the pipe due to '.a three foot relative I would , '~- I motion #135 exceed the yield point, but only slightly, and by an amount .-
'P?
that should not cause any serious problem. To reduceIthe strains to yield , g ey point values would mquire the introduction of flexibility at possibly two I?# of the joints or elbows in the pipe, or one or more bellows connections at the ends of the pipe run. It does not seen feasible to increase the ~ rl un T2 length of the pipe run from 80 ft. to 115 ft. , which would be the require- g' 9
- increasing
- e ment to reduce the strain to the yield point value merely by/ flexibility of %s:4 the pipeline itself.
s
?_23
.w The dynamic response of the piping depends on its fundamental .I period of vibratica and ,can be obtained from the shock response spectrum. M
;q .
Since both the weight of the piping and its stiffness. depend as its wall j thickness, the deflection of the piping due to a given acceleration is i' [.: *R independent of the wall thickness. On2y the diameter of the pipe and the - length of the pipe runs detemine the frequency of a pipe not carrying ; additional lead. For several diffennt configurations of pipe a fairly 1 - censistent relationship between maximum dynamic strain due to earthquake vibration and maximum strain due to movement of the supports can be obtained. The ratio of the maximum strain due to a spectral displacement, D, , for vibration at a given frequency, compared with the strain due to a D. relative static displacement at the ends, A , is approximately 2 3 J 1 ._ _ _ - _ . .
b Hence the earthquake strains which accompany earthquake motions will be of the same order as the strains for the three foot movement of the ends'if the earthquake displacement is approximately 15 ft. Pbr the pipe runs considered, Mr. Williamson estimates a period of vibtsbion of.the order of 1 to 2 secs. assuming hinged ends. Itr calculations indicate a period'of-
\
about 0 5 sec. for two fundamental modes, one primarily vertical and the ( .. other primuily horizontal, when the ends are fized. 6These periods are about twice as long, or. one sec. , for hinged ends. , The marien= ceabined A 1 J1 stress when both modes are excited is only slightly' greater than the h.I] ELS maximum stress for one of the modes. For a period of 0 5 secs., and for p.2:3 EM the PG&E spectrum in Figure 1 of Amendment 8. for 0 5% damping, the dis- .n i , placement is of the order of 0.25 feet, and for tvihe; this earthquake sfj Nf53 the displacement will be about 0 5 feet. On this basis, it can be j;j estimated that the strains due to the earthquake respcase an about ~[
- . n one-third as great as those due to the 3 ft. relative displacement of -
the supports. Hence, under combined earthquake and. relative displacement would [f
-i-bd due to faulting, the pipe althtbe overstressed, but not beyond three times i
-..g a -
the yield strain. It should be noted that the response determined above varies directly Ni as the natural period in the range from about 0.h sec. to som than 3.0 . sec. In other words, if the period of the pir.e can be reduced, its dis- h , placement will be decreased in the same proportion. However, reducing would, in general, '. the period of the pipe /adQGc require an increase in stiffness inngananar1, which would cause difficulties in resisting the. relative displacement of
, i the ends. Conversely, introducing flexible connections will in general
' ^ increase the period of the pipe which will increase the dynamic earthquake
'4 strains.
F j f . . . _ _ . m ____. _ _ _ _ _ . , .
.1 4
.. .. . - -.x : :_. .. . - u. . , , .
(.. 9 It appears therefore that some' further compideration' of the piping
*i design is required before assurance.can be given that the piping can sus'tain l both the ' earthquake vibrations, and the relative fault motions without be,ing ,
!/ l overtrained. - ( l-It might be pointed out in this regard t$at the maximum displacement s-of the pipe, should it become inelastic in an,e rthquake, v'ould probab3y. not be different from the maximum displacement were the pipe to remain
.. V elastic. . Hence the pipe, under the most serious ,m combination of conditions,- .
will be strained to about 3 times the elastic limit strain at yielding u..m. J (under the combined effects of the fault motion and earthquake motion). - 4 This is a bit severe, but might be tolerated. l. A,possible means :of reducing q rf.j the stress involus introduction of dasping by artificial means. - If th's , y M 1 I damping factor is increased from 0 5% to .aboutl20%, the dynamic dispincoments m y );;.t= are cut by almost a factor of 3. Hence, dampers .or snutbers attahhed to the ,' ~ 1 1 r.S pipe in some ' fashion may be required. 'Ihese should probab3y be attactied in
.:a such a way that they correspond to internal damping in the pipe ~ rather than Q
E.f absolute damping by connection to the grc4ad, sitice the latter will . (3 " introduce additions 1 disturbing forces in tho' pipe when' relative motions .
, of the ground or the containment structures take place. I~
All umbilical connections to the reactor cor;tainment structure, ;
, \
including the main steam lines, should be designed to assure freedom from' I c. contact with ottier structures, valls, or earth and rock, by such a distance under the containment building'- as to provide for the possibility of a three foot fault motioe/ and, in'. ., addition, the vibratory motion of the element con idered. ' Also, all vital' piping, etc. , must be arranged in such a var that,a three fact fault motion. occurring elsewhere in the azwa vill not cause a failure of the vital element. 4 4 k
- y. .
s
-e .p a s. 4 we a s.
, . _ _ . , - _ . _ _.3__ - - - _ . . . . . . - _.
~
- - 10 -
( 7 The main steam lines and similar important lines should be designed to be locally stiffened by sleeves or doubler plates, at points where ves or where anchors are attached, to prevent ovalling or their distortion of the lines that would impair /htus behavior.
,o ~~
i Ii i_[ ' Id r : -.. ..g
. . ?.k yy.
. ,. @~4 m.,
l
., .. ::s . .
k. i:'NU
-._; A
~y i.
. -r
' : .7 l.
t' .i.d.g 1 I I' 6 3
=
e i e t k t
+
I -. sue,- - p.--. .- + = - e
- 9 a.
N,
y_~..
, . ~ . . . _ _
l
, , f ,.
t ' ot.
-u- ;
y SAFETY OF AUXILIARY EQUIPMENT
- i. -
The auxiliary equipment contained within tlie reactor ;. containment ~ building will, in general, move as a unit within' this containment r. structure. . The fault displacement of 3 ft. for which provision is made does not produce a'similar displacement withii the structure, i' although it may produce a rotation or tilting of.the containment struc-ture. However, the equipment described in the ha*. and/in the Amendment 8 'elsewhere d r_ a.d xurtedomL application can certainly be designed for the slight . tipping ,$h or tilting and rotation, provided it is not rigidly', attached to items k; .a I. -< which move either a different amount or do not move at all.
~
g
.4..<
It is stated in Amendment 8 that "where vital 'omponents c of the !NM t; ; u
, . 4 emergency systems are located within the turbine generator foundation @]
j- :- of the control building, the inter-connecting piping and cable will be ' n~s
.. ?
designed to withstand up to 3 feet of relative displacement between M. 3j
'e the reactor containment structure and the turbine , generator foundation, 'H
(.j or control building." The provision of resistance to large relative Nj displacement combined with resistance to oscillations seene capable of ... achievement for relatively small diameter pipes, or for wires, although more - it is/ difficult for the 20 inch main steam lines. !
- , i SAFETY OF PRIMARY SYSTEM in t,his repor't Comments have been made previously/regarding t,he main stesa lines i
and the difficulties involved in providing the necessary resistance to relative motion and to earthquake vibrations. The statement is made in Amendment 8 4WollIIANIOpells that" accelerations experienced by the primary system during
- 1. such a displacement would be less than the acceleration used in the l
l. t
" ~
3
. .a ,_ '
. . _ . , - _ . _ _._.. _ _ _ _ . ___e..-.. . . ,
-{ ~
(u
- 12 , _
design of the equipment." It is not clearly stated that the accelerations-experienced by the primary system during the' maximum earthquake would be . , less than the acceleration used in the design of .the' equipment. Moreover, it is not clear, if the relative action'of faulting sbould exceed 3 'ft., whether there will not be a greater anximum acceleration 'than that pro- , i
\ .,
vided during the earthquake, owing to a possib1'e cra' s hing or battering of j ., the retaining walls outside the gap against the reactor containannt struc-
. ? ,
m .: ture. These could induce fairly large, but high frequency, accelerations.. fO i .-J Because of the large mass to be moved, the inertia of this mass, and the possible weakness of the walle of the reactor containment structure against . I1~ a localized line loading from outside, it is not clear at all that. a rela- #< could , - ' tive movement of'more than 3 feet uss be sustained',without producing serious damage to the reactor containment structure or serious accelerations = >. .: since fault motions' greater to the primary system within it. than 3 feet are not considered credible, Nevertheless,/ m t 4. P[} NRRP44RRRP416555NF questions of this sort BMExs55XIlaposug55sx need not-be considered, q ; Wf POSSIBLE INTERRUPTION TO SUPPLY OF POWER g
.a The vulnerability of the overhead transmission' lines has not been 9 s 9d
~'
establiebed. These lines cross the San Andreas fault, and although they -
. . ;y.<
are supported on widely spaced towers, there is a possibility that one . or more of the towers may be displaced by as much as 20 ft. relative to
'f _
( . a neighboring tower. It is possible that the towers can sustain such a i motion without loss of all of the lines. However, further study of this problem'is desirable if it is necessary to depend on ,this source of power.
- Amendment 8 hvemanammat states, however, that 't the externallsources are unavail-able the engine generator, located within the reactor, containment structure,
'4 s ~ , lh 4+ wow w es + '
%,,,e ,e %
a . a._. __.- . . . . ~ . . -- - i ..- ~ a t (. t -(- - 13'-- ,
. w will be capable of'bandling the load required to: shut down the plant safely.
L A further supply of power is available in the battery contained within tha reactor containment structure and control building. It must be regarded as possible that the maing verhead o tran==4ssion line would be ' severely! impaired in its functioning,where it crosses.the q main fault.* . l.
~
ABILITY OF STRUCTURES AND EQUIPMENTS TO RESIST EARTHQUA10B OSCIIIATIONS
.. . s The procedure described for the design of critical and non-critical of Amendment 8, structures, on pages 19-25/ appears in general, to be satisfactory, with S~1 1
minor exceptions.3 On page 21, the second paragraphi~ indicates that "thee M (
' design of the plant will be checked to assure that p critical'atructures, ..
w equipment and systems will be capable of withstanding earthquake ground motions corresponding to spectrum...(values)...two time's as great as abovn a m . -J on Figure 1 without impairment of functions..." This means an earthquake , of maximum acceleration of 0.67g, but not with acceleration spikes ranging "1. m up to 1.0g. The difference is not important for items having periods of .[2 vibration greater than about 0 5 sec., but it can be substantial for alements 7 - W2 s g.M. , having shorter periods or' higher frequencies, and the discrepancies become '
]
progressively larger as the frequency becomes higher or the peried becomes lower. A clear and unequivocal statement about this point would be desira- - i ble. k In general, there is a reserve margin in cimost.every element beyoal the point at which yielding begins, even in items of. equipment, control rods, fuel assemblies, etc. - Dr. Housner's study of the reserve capacity of structural elements, in Appendix II of Amendment 8, is sound. Nevertheless, - for items of equipment which are not designed for yielding at all,- but - which have to satisfy certain criteria such as clearance or magnitude of ' l
...-,%m - - . . - -
1
. ., , . . . 9:
~
{ (. L displacement, it is essential to consider the higher spikes of accelera-tion in their design in order to provide the necessary reserve margin to assure operation of these items under the extreme maximum conditions. 7n this regard, it should be noted that the dedign spectrum in Figure 1 is not quite as large as the values that correspond to the extreme p. peaks of the El Centro spectrum. The values in Figure 1 are in general _ those that correspond to the mean of the oscillations for the rather jagged i[..a) . peaks in the individual response spectrum curves for various earthquakes, k especially in the high frequency region. An envelope through the spikes h3-] Q Mg would generally lie about a factor of 2 above the smoothed spectrum, ~ W particularly for the low values of damping, although it would approach the h
*~f values reported for the higher values of damping. This is not regarded as
<3}
an important discrepancy, however, as there are indications that the mean of the oscillations in the spectrum is a much more significant value than
]
7.
]
the magnitude of the spikes. Calculations that have been made and that are s.% 9 - reported for equipment mounted on submarines, and for response of buildings y to earthquakes, in general indicate that the measured responses are more nearly consistent with the mean of the oscillations of the spectral values -= rather than with the peaks. Hence the smoothing of the spectrum is a rational and reasonable. procedure. L--- The accelerations transmitted to the reactor containment structure will not exceed the acceleration that will cause sliding on the sand layer, which may be from 2/3g to o.9g, depending on the characteristics of the sand, until first contact is reached with the side of'the cavity. Since this contact will occur after a three foot fault movement, or even less if some sliding occurs on the sand, a design level of 1.0g for proper functioning of equipment should be used. _ _ . _ . .. -.. - - . . _ - - - - - - - - - - - - - ~ ~ - - i -
'f *'[*0"# %yW MM '
d - g
, (
SUITABILITY OF PROPOSED DAMPING COEFFICIENTS The damping coefficients listed on page 23 of Amendment No. 8 appear in general to be reasonable. The degree of precision implied in the selec-tion of damping coefficients to two significant figures seems somevbat unwarranted. However, the values are in general reasonable for the stress s levels implied in the design of the individual elements, or for the con-ditions which are involved in their behavior. The' damping for the reinforced
.a concrete reactor containment structure would be considered high .for n structure , ,
appears to supported directly on the rock, but fugKbe reasonable considering the fact that ;$ L. e
. A Q
the structure is supported on a sand bed. For lov intensity earthquakes, possibly even for the 1/3s earthquake, if such is considered to be a design 2~i uv condition, the damping might be of the order of half as much as that used M D for the reinforced concrete reactor containment structure. However, for the ~_ ] . l maximum earthquake considered, the damping factor used is not at all unrerson- ] 1 able. __ ;
==G i
EFFECTIVENESS OF SAND LAYER IN CLIPPING PEAK ACCELERATIONS -3
.t.7 l
l In view of the comments on the behavior of the sand layer, it can be _ i concluded that the sand layer vill act to clip high peaks of borizontal accel-1 i
--4 eration that exceed its frictional capacity to transmit force to the reactor .
containment structure. It will not clip vertical acceleration peaks. DETAILED DYNAMIC ANALYSIS OF EQUIINENT l The mathod described on pages 23 and 24 for handling the response of equipment within the building appears reasonable, although for sensitive l items near the upper part of the building, the approximate method may not be adequate. A detailed dynamic analysis, such as described near the botton l of page 24, vill be desirable for all extremely sensitive and critical items 1 of equipment. The method of analysis described can take into account the
**--*+++--w-e,~,. .%%., .g..,% , ,
_- _ _X2
e _7_ { t.'. t , b interaction with the reactor containment structure itself. However, , Lthe ground accelerations or ground input actions considered should~ postulated correspond'to the maximum / earthquake, and not'the 0 33g earthquake for .4 . which Figure 1 of the amendment is drawn.- , The statement on page 34 implies that double the seismic loeds- Y corresponding to Figure 1.will be considered,' but this does not take. into account the spikes of acceleration ranging up to lg for the' higher '. . - - p frequency components. A further clarification of this point is desirable. g A$ ADDITIONAL 00lGG3fTS g
. . . M ~
The effect'of the water in the annulus surrounding the reactor con-tainment structure should not,in general,cause accelerations to be trans- h*C2
- mitted directly to the structure through the water' because of the fact that the water has a free surface. However, it would be desiraMe to have j a study by the applicant of this problem to insure that.the surging of the y b.
water will not introduce additional oscillations within the structure. F5
' M This does not seem likely and it appears most reasonable to expect that the .
water contained in the annular space will damp the motion of the structure. [
~
Nevertheless, no specific data on this topic are available.
.s
~a '
In gene::al, althou(;h questions have been rais2d about the treatment' ' in certain aspects of the amendment, it is not believed that any of these questions involve problems that are not possible of solution within the range of currently available engineering knowledge. It is acr considered essentially as proposed opinion that the structure and its equipment can be designed /to resist
; the effects of the maximum earthquake postulated.
9 b v
' f ,
,em. ,~,em. s w __ -a..
y-, y7.,n .g , g -~,,y .7. m- - g.-
, 7. -- -
7..-.~.-n.g{.~g. ,,,-,- ,q}}