ML20235X805
| ML20235X805 | |
| Person / Time | |
|---|---|
| Site: | Bodega Bay |
| Issue date: | 12/04/1963 |
| From: | Williamson R HOLMES & NARVER, INC. |
| To: | Hadlock G US ATOMIC ENERGY COMMISSION (AEC) |
| Shared Package | |
| ML20235X376 | List:
|
| References | |
| FOIA-87-462 NUDOCS 8710200120 | |
| Download: ML20235X805 (15) | |
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Dear Mr. Hadlock:
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.. > :v Transtnitted herewith is a draft copy of my report on the Bodega Bay Atomic Park Unit No.1, Seismic Considerations in Design of Facility Components, revised as of this date. This (ocument j
i evises the preliminary draft of June 14, 1963, and brings the I
report to as complete a state as can be achieved at the present i
Umc. It incorporates numerous revisions throughout which are best identified by comparing with the previous draft.
The present draft contemplates that this report will be separate i
from that of Dr. Newmark. I advised Dr. Newmark of this in a
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telephone conversation with him on November 27,.1963. I sub-sequently forwarded to him comments in writing (copy enclosed
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l nerewith) and a copy of my own revised draft.
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Come time ago 1 mentioned to you the press release of Mr. Ackerman j
l which I obtained at the ASCE Conference in S' n Francisco. Trans-a mitted herewith is a reproduction copy of this document which you i
may find interesting. I am also transmitting herewith five copies of earthquake spectra 'in logarithmic form adapted from the spectra given in TID-7024, " Nuclear Reactors and Earthquakes". These 1
l aheets may be of some value to the technical members of the AEC l
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, l-i G. F. Hadlock December 4,1963-During my conversation with Dr. Newmark he expressed an interest
- in having a copy of TID-7024. If he could be furnished with a copy I am sure that he would appreciate having one.
I hope that this submittal fulfills the immediate need. I will be glad to consider such revisions as you consider necessary in addition to the other changes required to complete the document.
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Sincerely, t
HOLMES & NARVER, INC.
- f(ft brxam R. A. Williamson I
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My present plans call for taking my vacation stdrting'Tiext week and continuing through Christmas. In this period I.
I can be contacted indirectly through the office or directly by wire or phone, at 9217 Dorrington Place, Pacoima,
.i California (EM 2-1836, Area Code 213).
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M SEISMIC CONSIDERATIONS IN DESION OF FACILITY COMPONENTS.
l General This re.lew, which discusses'some of the considerations requiriny i
special attention in seismic design, is based on a ' study of the materia]
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-l in Refs.1 through and also on discussions with staff members and other consultants of the. Division 'of Licensing and Regulatied." To
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define the earthquake resistant features' to the: extent which,would permit a detailed investigation of their adequacy..is not genera 31y' pos-sible in advance of final design. Such investi'gation is a future effort which is a part of the applicant's design responsibility. This review is intended to provide general guidelines. and is based primarily on considered judgement, supported, in some instances, by very_ rough calculations utilizing conservative assumptions, j
Structural integrity of the facility depends on the absence of. gross differential foundation movement. Conce.vable movements of this mag--
nitude might be associated with slippage of faults located directly be-f ndath the site, structural weaknesses in the granitic base. rock,' extr syr conse..dation of the s5Ils overlying the base rock or lar.dslides in th.t se s oils. It is emphasized that this statement does not necessarily imply
'that such movements are likely but merely underscores the fact that it would generally be impractical to design an installation to survive large differential displacements of the foundation, and the ensuing dis-cussion assumes that large movements of this nature do not occur.
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The discussion further assumes that the seismic effect de' scribed
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by the ground accelerations, spectra and damping factor's presented in '
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and is acceptable as a design basiiwhen utilized with appropriate design methods which consider dynamic response.
l The use of dynamic methods based on the. response spectra propos,ed' by the applicant for the design of critical components (Clans 1) leads o amplified accelerations which, in m'any ' cases', are significantly greater than the maximum ground' acceleration'itself. The resniting_
inertia forces used in design _ generally will be at least several times those recuired by the earthquake provisions of California buildir.;
c ode s'.
Seismic resistance depends on response of numerous components
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1 whose structural integrity is generally ignored when strong ground
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motion is not a' factor. Because of this, many featurer. customarily cons:..iered non-structural, including components of mechanical and ele.:rical systems, require special attention in design to avoid weak j
lit.ks in the system. Therefore, the discussion considers these items,
at well as those usually classified as structural, j
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Criticil Components i
or al. items vital to safe shutdown and containment the applicant y.oposes.
monstrate that a
%g earthquake would not cause loss l
of function of the vital structures of the reactor and that a
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earthquake would not cause loss of function of vital process. components.
Items such as the following along with associated supports, co..trolsr.-. _.
instrumentation and circuitry should be considered as falling in t'. ase categories:
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Reactor substructure, steam and feed water lines between a.
reactor and turbine, pressure v'essel and and internals, dry well and suppression chamber.
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Controls, control rods and drive system.'
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-T Power and water. sources, pumps, prime movers and piping c.
essential to the function of the em9rgency cooling system.
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Spent' fuel storage pool.
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Refueling building.
3.
F.eac::.r Substructure an'd Turbine' Pedestal Jne reactor substructure (cylindrical reinforced concrete enclosure surrounding the reactor) is necessarily very massive because of consi-
- . era: ions other than those of a seismic nature, such as static earth and water pressure. Under normal conditions these pressures, at any e'., will be essentially uniformly distributed around the periphery of 3
l tha substructure. Transient unsymmetrical pressures may occur under i
I ez.rthquake conditions. However, it should be feasible to provide the necessary reinforcing steal in the substructure to resist the combined i
j' stresses from all Imposed loads, including those of seismic crigin.
Special treatment may be required for thermal stresses in the region 4
of the dry well. Internally, the substructure with its compartmented'
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interior is highly redundant and will require the use of overlapping as-
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sumptions in design; however, in'these areas seismic considerations P
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should not be.of major importance.
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The tt.rbine pedestal is situated on soil, whereas the. reactor sub-0 5
structure is founded on bedrock. The soil report (Ref. 5) contemplates b.
the possibnity of about one inch differential settlement between the two structures, most of which would occur during construction. However, 4
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i in the design of critical piping and any other non-expendable components l
crossing this joint, it is felt that allowances should be made for not less than several inches of diffe ential settlement to arrive at maximum as-e surance again,st rupture of taese vital elements. There should be no insurm'ountable problem in designing the supports of the turbine and generator to resist high seismic forces. Seismic effects on the supports l
will be minimized by maximia.ing the lateral' rigidity of the piers and shear walls.
4.
P'
- d Equipment, t
4,1 Ocneral Special care is mandatory in the design of those piping sys-tems e,f the facility which are critical from a safety viewpoint becaus e:
fg-(1) r..nimization of thermal stresses calls for a minimum amount of #'
t res:raint, whereac minimizing of s eismic stresses requires the op-posite-leading to a conflict which must be resolved in design; and (2) the usual static analysis using factora of 0. 20g or less may result in.
significant overstress in an earthquake of the anticipated intensity.
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N Where pos'sibic, brittle mrterials should be avoided in all elements of the piping system stressed by earthquake motion. Where use of such materials is unavoidable, stresses should be kept well be-low the elas:ic limit under the most sever e combinations of loadings i
anticipated :n the safe shutdown condition. This li nitation should apply
'not or.ly to the piping and pressure vessels but also to supporting ele-ments, all appurteraces, including valves, and to pumps and their c onnections. Radhtien embrittlement may require consideration in this respect.
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- 4. 2
Response
The equipment elements, including such componento as pumps, motors, valves and pressure vessels and their supports, along with the connecting piping constitute a highly elastic structure with low damping, rdquiring consideration as a dynamically loaded system. It is not un-usual to find that the fundamental period of such a system lies in a range which maximizes the response to close-in earthquakes. This combination of factors can amplify significantly the effect of ground motion. For example, the ground' motion criterion proposed in Refs.
and wi:h its peak accelert. zion c; g could in some. instances, induce stresses which would approximate those caused by a static lateral force of g acting on the system. On the other hand, where by design or circurn.,:ance, the fundamental pc-iod of a systern is very short, say in the range of 0.05 sec. or less, seismic effects are minimized, and the stf esses can approach values as low as those resulting from a static late a1 force of g acting on the system.
- 4. 3 Differential. Motion l
In addition to the significant differential motion which often must be expected Nte to seismically induced oscillations in piping systems connecting pieces of equipment mounted on a rigid common support, piping connecting equipment mounted on separate foundations may be subjected to the effects of tilt and rela +.ive displacement of the foundations. Lines vital to safe shutdown, and extending from the reactor to adjacent struc ~
tures supported on soil fall in this category. The design should insure that the effects of seismically induced oscillation of these lines, plus those due to the estimated differential displacement between the reactor structure and the adjacent structures will not cause overstress when combined with operating stresses. Such lines should be capable of tolerating at least several inches of differential displacement without I
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incurring large stresses. The same type of criterion should be applied to any other line of critical importance which crosses such an interface.
Buried piping may be subject to differential displacernent of the surrounding soil. Un'ess it is clear that this type of ground move- _ -.'._
ment is not credible, vital runs of buried piping should be protected through measures which will accommodate.the maximum differential displacement without overstressing of the pipe. This protection might I
consist of naeasures such as enclosure in oversized conduit and use of flexible j ts and loops.
- 4. 4 S_tres s Analysis Manual stress analysis of a complex piping system requires the use of simplifying assumptions, but may be entirely adequate if it' can be determined that the results are conservative. Computer pro-grams originally used for analysis of dynamically loaded piping systems in nuclear submarines have been applied to evaluate earthquake effects j
in piping systems of nuclear reacto-facilities. This approach should be considered.
5.
Pressure Vessel and Internals There should be no unusually difficult problem in bracing the pres-sure vessel laterally tc resist earthquake-induced forces in such a way that the thermal expansion movements can be accommodated. The in-ternal parts contained in the pressure vessel should be investigated for the effect of the induced forces from the ground motion, includir g that associsted with " sloshing" of the. coolant.
6.
Dry Well and Suppression Chamber Stresses from' seismic effects on the dry well and suppression l
l chamber should not create serious problems as compared to those from-
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thermal effects. If the concrete is poured directly against the steel 1
shell throughout, the shell becomes essentially a liner and special bracing for earthquake effects may not be needed. At the other extreme,
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isolation from the concrete would require the use of seismic bracing.
Stre'ss conditions at penetrations customarily require special atten-l l
tion, even in the absence of a seisinic threat. These stresses may be i
amplified by seismically induced inertia forces. In addition " sloshing
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action" may require consideration as, for example, in the case of com-I
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l ponente orojecting into the suppression chamber area.
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7.
Control System An important consideration in regard to the control r'od system is the need to provide countermeasures against the possibility of binding
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l or other malfunction arising from seismically induced forces, deflections.
l or distortions.. The extent of the problem depends on reveral factors in-c'.udin g : (1) the effective length between supports; (2) types ano magni-tudes of reactions and restraints at supports; and (3) the magnitude ofg flexural and axial stresses. Special attention is needed in the design of
'N operational features to be certain that malfunction will be of the " fail-1 1
4 safe" type needed to cause a scram. This system is of such importance l
I that its seismic integrity warrants extremely careful study, i
1 Deficiencies in mounting are potehtial sources of damage to compo-l 4
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nents of control systems. Adequate anchorage of such items.as instru-l ment panels and cabinets and " shipboard" stowage practices should be l
effective in minimizing the threat of damage to the control system and f
possible injury to the operator during a severe earthquake.
Some of the emergency actions are manually performed. Since the typical human reaction to a strong earthquake is one of fright, operator t he.
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error could be the result. Hence, serious consideration should be given to earthquake drills, particularly with respect to operation of controls involving emergency shutdown.
8.
Power Sources it is questionable whether transmission of power from remote sources can be considered entirely reliable'in a severe earthquake, l
particularly with regard to circuits crossing the San Andreas fault, I
Malfunctions of transmission and distribution systems in California have t
occurred in strong shocks. Emergency sources located at the facility are inherently more dependable for use under seismic conditions if l
properly designed. The emergency engine-driven generator, fuel l
9 sources, station battery and associated circuitry should incorporate,
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adequate anti-seismic features and, where essential for reliability, re-dundancy should be provided.
l 9.
Water Sources 1
The toroidal suppression chamber probably has a high degree of I
reliability as a fluid container under seismic conditions. Cons equ ently, seismic problems are reduced if the volume of water in the suppression pool is adequate as the sole source of emergency coolant in a strong ear thquake. However, if auxiliary emergency sources ar,e needed, the auxiliary containers and supports and associated piping require special i
attention and should be designed for maximum seismic resistance.
- 10. Spent Fue1 Storage Pool Seismically ihduced increments of water pressure acting on the side walls of the spent fuel storage pool cause no major structural difficulty.
However, percentages of reinforcing in the walls should be sufficient to prevet.t seepage through cracks. Use of a' metal liner (which may be desirable for other reasons) would avoid any question regarding potential
-8,
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e leakage from cracking'of the concrete. If flooding of the interior of the refueling building is to be avoided, sufficient freeboard should be pro-vided above the normal water surface to avoid over-topping from the wave action generated by the ground motion.
- 11. Refueling Building The junction between the circular reactor substructure and the squarc refueling building requires special measures for support of the projecting corners of the refueling building. However, seismic consi-l derations should not cause extreme. difficulties in this area.
It appears feasible to use the roof of the building as an earthquake diaphragm, with the walls functioning as shear walls. In this event, there should be no problem in attaining the required resistance against seismic forces acting in the plane of the wall. To resist forces caused 1
oy ground motion normal to the plane of the wall will require reinforcing steel in amounts much greater than usually provided. Bond beams or other equiva.ent supporting features may be needed at large perimeter,
openings in the operating floor, such as those occurring at the spent fuel storage pool and the cask removal area, to provide lateral support for the seismically loaded wall above and below.
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- 12. Inspection After a Severe Earthquako As stated in Refs 1, it is the intent to provide for continuous operation through a major earthquake. Hent i, should the facility continue to function during and after a severe earthquake, the need for an inspection.
shutdown would have to be decided. Such a decision could be based on information such as that obtained from:
a.
Inspection of those features which are. accessible-during_
operation.
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b.
Assessment of the earthquake intensity (preferably from one or more instruments located at the site),
c.
Examination of operating records for any evidences of unsafe conditions.
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In an inspection operation, priority should be given to examination of the components which are most important from the standpoint of public safety. These would be distinguished from those components needed primarily to insure continuous power output, and whose failure l
would not constitute an off-site haz.ard.
Conditions such as those at bends, penetrations of vessels and at connections to equip, ment, including pumps and valves, should be ins -
pected. Such inspection could be visual, radiographic, ultrasonic, dye-penetrant or other type as appears to be dictated by the particular circumstances.
I Inspection of the reactor substructure, refueling building and turbine pedestal for evidences of overstress should be made. This would include such items as determining the location and extent of cracking and spal-l ling of concrete and searc'hing for evidences of slippage or yielding at connections, and tilt, settlement or differential movement of foundations and soil.
l
- 13. Seismic Instrumentation Serious consideration should be given to the installation of one or more strong motion seismographs or other instruments at the site in view of the possibility of an intense earthquake. Instrumental recordings l
of strong ground motion would seem to be of the same order of importance as the recordings of wind direction and velocity included in the meteor- -
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ological program to be carried out at the site. Instrumental data could be useful in determining whether a post-earthquake inspection shutdown should be made.
- 14.. Design Coordination The earthquake problem affects all the engineering disciplines in-volved in the design of a reactor facility, including not only structural and architectural engineering, but mechanical and electrical as well.
The structural engineer is most familiar with earthquake problems as they relate to building structures.. Typically, however, with the pos -
I sible exception of some piping systems, mechanica'l and electrical components are seldom considered from a seismic viewpoint by the structural engineer or the mechanical or electrical engineer. On the other hand, it should be noted that structural, mechanical and electrical h
systems have been successfully designed to resist very severe shock inputs in nuclear submarines and also in missile facilities " hardened" against nuclear attack.
The importance of achieving consistency in earthquake resistance requires that each component be looked as part of an overall system.
It further requires special provisions on the part of the d' signer for e
insdring seismic integrity at interfaces between various engineering disciplines and various areas of responsibility.
5,
- 15. Conclusions The following conclusions assume: (1) the absence of gross dif-ferential foundation movements; and (2) that the spectra, damping factors and design approaches proposed by the applicant are acceptable.
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The ground accelerations proposed by the applicant generally a.
are several times greater than those required by conventional California power plant piactice or implied by the seismic pro-visio,ns of building codes in earthquake areas, b.
The dynamic analysis approach proposed by the applicant leads to seismic resistance requirements which significantly exceed those of conventional California power plant practice.
It is not possible to make a detailed and. comprehensive assess-c.
ment of the seismic resista,nce of various components prior to design. However, indications are that the problems arising
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capable of solution using known engineering practices.
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In my opinion, the reactor can be safely designed in accord 4'
i ance with the factors stated herein, to withstand an earthquake of the predicted maximum intensity. To insure that adequate seismic protection is provided, careful attention must be f
1 directed to a number of considerations during the detailed
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design of components and ' ystems. In final design all critical s
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elements should receive a dynamic analysis to assure that
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stresses and deflections are within acceptable limits.
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0 REFERENCES j
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Preliminary Hazards Summary Report, Bodega Bay Atomic Park Unit Number 1, submitted by Pacific Gas and Electric Company,'
December 28,1962, (Docket No. 50-205).
j
'5*
2.
Arnendments 1 and 2 to Docket No. 50'-205.
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Preliminary Soils Invesdgation and Seismic Survey, Proposed Nuclear Power Plant, Bodega Bay, California, for the Pacific
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Gas and Electric Company, by Robert D. Da'rragh and John F.
3
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Stickel, Jr. of Dames and Moore,' Consultants in Applied Earth-l Sciences, December 2, ~ 1960.
4.-
Report of Seismic Survey, Proposed Nuclear Power Plant, Bodega Bay, California, for the Pacific Gas and Electric Company, by John F. Stickel, Jr. and Robert T. Lawson of Dames and Moore, f
Consultants in Applied Earth Sciences, January 25,1960.
5.
Foundation Investigation, Bodega Bay..tomic Park Unit Number 1,
[
Bodega Bay, C'alifornia, for the Pacific Gas and Electric Company, I
by Robert D. Darragh of Dames and Moore, Consultants in Applied l
Earth Sciences, April.30,1962.
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E 6.
Amendments
,and to Docket No. 50.-205.
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'N s t ATTLE. WAs H.. e s t o s '
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February 7,1964. D(Plle co; g j
Mr. Robert Lowenstein; Directn
' Division of Licen' sing and Reguk cion,
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U. S. Atomic Energy Commission.
r Washington 25,-D. C.
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Dear Mr. Lowenstein:
Thahk you for your letter of January 24,.1964
- s forwarding me a copy of Amendment No.~ 5 filed by the Pacific Gas l
azid Electric Company. (Your file 50-205). Af ter more delay than e
I expected, due to local act.ivities, I am enclosing'several pages-l of comments on thos.e items which concern seismology.
j
.i Mr. Robert Bryan has informad me of the'confereno's to be' l
held in Washington.next. week and I am looking forward to seeing,
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you then.
s Sincerely your,s, l
Yh4 a
Frank Neumann.
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Enclosure:
Comments on Pacific Gas and Electric Company's Amendment No. 5.
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i CDm!ENTS ON PACIFIC GAS AND ELECTRIC COMPANDS AMMENDMENT NO 5 l
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J (Containing statements by Tocher and Marliave,' Hu6o Benioff and h.Quaide)
By F. Neumann j
Geologic and Seismic Investigation of the Site for a Nuclear Power Plant on Bodega Head, Calif. (By Don Tocher and E. C. Marliave.)
Page S.
It is stated that exposed rock on Point Reyes Peninsula is simi-i lar in character to that on Bodega Head.
It is'also a fact that the aux-
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iliary fault movement on the peninsula in 1906 was very close to the epi-1 center of that shock. With these two facts in mind one may assume that j
if a shock of 1906 intensity originated near Bodega Head auxiliary faults adjacent to the principal fault might also be expected to slip including that found by Schlocker and Bonilla in the P.G.&E. pit (TEI-844). In other l
words there is strong support for the idea that auxiliary faults may slip where the fault movements and vibrational intensity are the greatet,'name-i 3
l ly, in epicentral areas.
Pp. 12-13.
Tocher states categorically the "it is possible tocreate I
a suitable an.1 safe design". The writer does not believe that earthquake
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engineering has developed to the point where such a matter-of-fact state-ment can be made. Practicing engineers would not doubt be the first to J
admit that there are many shortcomings in the art and that in tho' final analysi the effectiveness of earthquake resistant design is largely a mat-ter of good judgment on the part of the desi n engineer. Until buildings 6
designed to resist strong earthquake forces are actually subjected to forces as severe as those of 1906 there will be no proof that the earthquake en-1 gineer has really mastered his art or even that it is economically feasible to. design standard type structures that will successfully withstand a very
,j violent earthquake.
4 P. 14.- It is stated that the Et intensity scale is misleading for l
large shocks; ground phenomena -- faulting, fissuring, etc. -- indicate V
one ' intensity while building damage in the same area indicates an entirely different intensity. This is a partially legitimate criticism. The writer has never felt that non-vibrational phenomena occurring in the ground are an adequate measure of vibrational intensity, and that is what is really
'j meant by intensity -- the degree of violence of the shaking. Slipping a-j long a fault, or fissuring due to slumping are not practical measures of vibrational intensity and the scale must be interpreted in that light even
(
though in its present state of development no distinction is specifically l
made. The fact that intensity as measured by @uilding damage my vary
- ' 2; greatly over long stretches of active faulting is photographs are available to illustrate the point)quite well known (many I
but this fact still needs l
to be recognized in'the scale. Mr/ Wood in, developing this scale mado 'a
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notable contribution to engineering seismology and would'(if he were alive) be the last to claim perfection in its present form.
Even in its present form the writer has found the scale eminently use-ful for both engineering and purely seismological studies. The consistency j
of results obtainod are proof of this. The writer's recent 'ohart,.for example 4_.___
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intensity is quite as valuable and accurate as a measure of this form of i
earthquake energy as earthquake magnitude nunbers which many seismologists
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(especially Californians) are quite ready to accept for no other apparent i
reason than that it is based on a more sophisticated type of data, namely, y
teleseismic records. Magnitude, of course, is a measure of the total ener-gy released at the focus of.a shock but the magnitude formula is still in a state of development the same as the MM intensity scale.
The writer has grown weary of the claims made by critics of the MM' intensity scale that the data (largely post-card questionnaires)are of questionable value because of their subjective nature and because they in-volve no real measurements. To counter this claim the writer argues that r
any person of average intelligence who has a reasonable. knowledge of what is going on about him can supply information that will enable the seismol-ogist to detennine whether a particular disturbance suggests 2, 4 or 8 times the ground motion suggested by some weaker disturbance. This is the situation when the seismologist evaluates descriptive reports involving four successive grades of intensity.
If one disturbance involves double the ground motion, or half the ground motion of some arbitrary disturb-ance the writer believes that the average layman is capable of sensing this difference through what his community feels and sees. The writer feels that his researches over many years have proved this point. No critio has yet published any material that would invalidate the writert findings other than expressing broad opinions on seismic phenomena that they have obvious-ly made no serious effort to understand.
Tocher cites the response spectrun technique as the best quide line for intensity. Having suggested the first feasible method (the torsion pendulum) for determining oscillator response spectra the writer is quite familiar with their value to earthquake engineers.. For a multitude of reasons that are evident in the writer's various memoranda to the A.C.E.
the response spectrum will never serve as a sdstitute for MM intensity if for no other reason than an oscillator response spectrum may cost hundreds or even thousands of dollars while intensity data are obtained at virtually no cost whatever.
In su= mary the writer does not attach too much weight to Tooher's o-pinions in the field of engineering seismology because he has been a spoo-tator rather than a worker in this field.
P. 34.
Tocher's assurances that future faulting along the San Andreas l
l will be confined to the present 1-mile. width (near Bodega Head) is pure l
speculation. We know so little about stress patterns in the deeper rocks that no one can predict with certainty whether the next big slip will lie within or without the present zone of fracturing. What investigators think about such matters and'what they know about them are two entirely different i
. things.
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MOVEMENTS AND SEISMIC DESTRUCTIVENESS ASSOCIATED WITH THE '
SAN ANDREAS FAULT. (By Hugo Benioff)
Pages 1-3.
In describing the mechanism of earthquake faulting Benioff places no emphasis on his fault look theory presumably because-it conflicts with Housner 's " planar energy ' source" concept. Nevertheless -
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in item 4 of his conclusions' he states (with reference to the one' mile width of the zone of. faulting): "This wandering of the break has occurred s
--- as a result _of departures from linearivy of segments of'the fault'- ".
This ' brings him back not only to the fault look concept but he uses this concept to-explain the 1 mile width of the sone of fracturing..
P. 3. In stressing the-presence of only small oscillatory motions -
in the immediate vicinity of a~ fault Benioff leans heavily on theory with <
little if any supporting evidence from observational. facts.. An extremely few close-up blast-like records might support his view -but it otherwise L
has little support from either instrumental records or field observations.
1 Low intensities along faults can always be found~at great distances from-an epicenter but in immediate epicentral areas the intensity reaches a maximum. He states in effect that at 2 to 12 miles from'the break the intensity is constant. The writer has found (as shown in graphs furnished l
the A.E.C.)'that intensity in basement rock is generally a maximum out to a three mile limit where it decreases exponentially with increasing distance.
The Benioff concept as outlined in' Amendment No. 5 calls for supporting evi-dence.
This, however, along with the time"it takes for a. fault to rupture dotnot seem vitally pertinent t > the problem in hand because no one knows l
just where the next big shock will originate in this area.
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'l When Benioff on p. 4' quotes Housner as obtaining.3 g on rock and.5g on firm alluvium in the 1940 Imperial Valley earthquake he differs but little from the writer's values if reference,is made to the epicenter of the shock rather than the seismograph station. site in El Centro.
Benioff apparently does not tako ~into consideration the complications
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that can be introduced by multiple look breaks. That such phenomena are V
quite co:: con is strongly supported by both instrumental and noninstrumental-1
,l evidence; it is quite simple to locate an. initial-break from teleseismic S
data, while a second and generally greater break'(or secondary epioenter) is indicated by the concentration of-higher intensities at.some other. point.
The Long Beach earthquake of 1933 was a notable example.-
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P. 4. Benioff attributes the fault traversing the reactor pit to a.
slip along the San Andreas zone of fracture. As might be inferred from'the i
previous discussion.of the Point Reyes ' peninsula slip in 1906 it is very -
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probable that when the pit fracture did occug, the ' epicenter was quito close to Bodega Head.
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- P. 5. Benioff states that ine,ctive auxiliary faults will not suddenly exhibit significant movements during a slip on,the principal fault. How
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is he sure that this did not happen on the Point Reyes Peninsula in 19067 -
Does anyone know definitely whether this auxiliary fault was previously-active-or inactive?-
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4, P. 5. By way of explaining structural response to complex earth-quake motion Benioff goes to considerable length to explain that reso-nance is a primary factor in damage.
This is basically what response spectra show if resonance is indicated by the ground and oscillator periods.
He stresses duration as one of the controlling factors in damage and to this extent agrees with the writer that duration is also a factor which governs intensity.
P. 8, item 6.
Regardless of the reasoning behind it single maxi-mum acceleration factors are still a significant part of current build-ing codes and will probably continue to serve as equivalent static ao-celebrations for a long time to come.
The writer han discussed this in certain A.E.C. memoranda and believes that such acceleration factors serve a useful purpose when properly interpreted, Shat is, when eyeluated l
in the light of theoretical spectral accelerations.
P. 5. The writer does not believe, as previously stated, that the use of EM intensity scales in engineering design constitutes unsound practice.
The reasons for this are evident in various memoranda furnished the A.E and especially in a su= mary statement forwarded in November,1963.
ioff may be justified in stating that the equation he quotes, for acceler-Ben-ation, represents pure nonsense.
It yields only an average value whereas the true relationship between intensity and acceleration is quite compli-cated.
The writer believes that in breaking down earthquakes into four broad types (as shown in various A.E.C. memoranda) he has corrected the major deficiency inherent in the equation quoted.
P. 9, item d.
Whether or not a structure can be built in the P.O.
and E. Co. pit that will suffer no significant damage is primarily an engineering problem.
a seismologist.
Like Tocher and the writer Benioff is primarily Papers by Tocher and Quaide. The last two papers in Amendment No. 5 by these authors are primarily of geological interest and do not concern seismology except where one of them attaches special significance to the fact that no epicenters have ever been found on Bocaga Head.
i to be certain that no earthquakes, including those too small to be feltThe only way are occurring or have occurred there is to ' operate a' sensitive seismograph right on the Head.
of shocks strong enough to be felt had been established.Up to 1930 no l
Instrumental con-trol over the area has been quite inadequate except over the last two or t
three. decades, and even if adequate control had been maintained over the past 100 years a history of quiescense would not be a guarantee of future immunity in an area as active as this.
Judging by the nunber~of strong-motion earthquake records obtained since 1932 4he northern California area is less active than southern California yet the grea'est known California f
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.J April 21,1964 Mr. Edson Case Division of Licenses and Regulations U'. S. Atomic Ene rgy Commission Washington 25, D. C.
Dear Mr. Case:
Af ter the meeting at Bethesda on April 14, I requested that your secretary reproduce a copy of my comments on PGLE Amendment #6 which I assume Some of the comments therein were not discussed in the meeting.
you have.
Herewith I am transmitting a similar set of comments applying to PG&E Amendment #7. At the time of the meeting these were available only in very rough form. For this reason, I could not furnish a copy at the time.
The material in these comments may be useful particularly since it pro-l vides you with specific information which should be adequate to enable you l
to obtain the H&N & Newmark reports on tunnel liners.
Sincerely yours, l'
HOLMES & NARVER, INC.
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Comments on PGLE - Amendment #7 This amendment appears to merely present in writing what was stated e
verbally by the applicant before '.he ACRS committee on February 24 and provides little if any, amplifying information. The following are specific comments.
1.
On page 2 the proposal,is made to fill the annular. space between the containment structure and the adjacent rock with a layer of compressible material of a type yet to be selected.- It is assumed that this statement applies also to the space between the wall of the containment structure and the adjacent soil above the rock. The statement " type yet to be selected" might better read " type yet to be deve loped". The general subject of frangible filter materials has received a large amount of study in recent years in connection with underground facilities hardened against nuclear attack. This effort has included tests at the Nevada Test Site.
Various government agencies have been involved including the Waterways Experiment Station, Vicksburg, the Corps of Engineers and the Defense Atomic Support Agency (DASA). The University of Illinois has also been in-volved as well as the firm of H&N. Among the various materials I
investigated have been plastic foams, such as polyurethane, vermi-culite concrete, perlite concrete, and volcanic cinders.
Polyurethane Foam 1
The firm of H&N has utilized plastic foams in connection with shock isolation of towers, winch footings, and other similar installations at the Nevada Test Site. Soft foams are subject to creep. This tendency is increased at low temperatures. The soft foams also tend to lose strength under exposure to moisture, but the harder foams are less effected. A foam with a compressive strength of about 150 psi weighs approximately 6 lbs, per cubic foot (and therefore tends to fload and costs roughly about $1.00 per lb. or possibly 3 times the cost of con-ventional cc.nc rete. A foam in this strength would not be greatly effected by creep or exposure to moisture. It will sustain a compressive deformation of approximately 5084 before locking.
Vermiculite Concrete This concrete consists of Portland _ cement and aggregate consisting solely of.ve rmiculite. The vermiculite aggregate has directional pro.
p e rti e s. However, when in concrete the random orientation of the particles causes reasonably uniform directional characteristics.
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Comments on PGLE Page 2 Vermiculite concretes in the range of 150 to 200 psi strength have been made. Unit weight in this strength range is less than that of The yield range, unlike that of polyurethane foam, has a wate r.
decided slope upward, and, in the case of a 200 psi concrete, the locking range appears to begin at about 25% elongation. The Water-ways Experiment Station and the University of Texas have both in..
vestigated the properties of vermiculite concrete.
The information obtained at the Nevada Test Site in connection with tunnel liners is contained in the following H&N report: Holme s, Kwan,
Skinner, and Wong Loading Response, and Evaluation of Tunnels and Tunnel Liners in Conc rete - Operation Nougat, Shot Hard Hat, Project 3.1 POR - 1801, for Defense' Atomic Support Agency, July 1963 (Se c r et).
The data obtained in this report formed the basis for a sub-sequent report prepared by Drs Newmark and Merritt entitled Design of Test of Nearly Invulnerable Structures in Granite (Secret) which is identified with a new series of tests now being proposed at the Nevada Test Site.
It is my understanding that the linings to be investigated will include polyurethane foam and some new types of foam concretes.
One factor to be considered in the use of frangible materials is their effect on the response of the structure.
The deformations of these i
materials in the yield range are irreversible. Consequently, ocilla-tions of the containment structure causing lateral pressures sufficiently intense to compress the material would tend to leave an annular void.
The structure would then be in contact with the oscillating ground at the base only.
This could possibly amplify the input oscillations re-ceived by the equipment within.
Whether this void could develop due to ground oscillations alone, in the absence of displacement of the reactor fault should be investigated 2
Amendment #7 appears to assume that the movement is along the existing reactor fault.
Mr. Schlocker of the U. S. Geological Survey expressed the belief in the ACRS meeting of February 24 that differential move-ment could occur along any line beneath the reactor and not rnerely along the existing fault. If this is considered to be a credible pos sibility, then PGkE should resgudy the problem. It should be noted that a movement at approximately 90 to the existing reactor fault could cause collapse of the wall in the region of the steam linas with the possibility of damage to-the isolation valves.
The entire amendment lacks any discussion regarding
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4 Comments on PG&E Page 3 malfunction of critical equipment caused by contact with caved-in walls and, in fact,- there is 'no discussion at all which indicate s the extent or nature of the investigations which lead to the conclu-sions given.
3.
Amendment #7 needs to be considerably amplified in order to be i
considered adequate. There should be some description of the number and kind of outside sources of water and power and other umbilical features which must remain intact in order to permit safe shutdown. There should be proof that the isolation valves will function and that all other elements of the containment will remain intact. This situation calls for explanation substantiating the mere s:atements that survival is possible.
'4.
The sketch submitted with the amendment is vague in its delineation of the limits of the concrete, particularly in the area around the toroidal suppression chamber. It should be revised to remove this l
I confusing ambiguity, i
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Dr. Marvin Mann, Assistant Director-Nuclear Safety Division of R eactor Licensing U. S. Atomic Energy Commission
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Washington 25, D. C.
Dear Dr. Mann:
i During our meeting at Bethesda on May 15, I provided you with a draft of comme.nts concernin.g the proposed Bodega reactor and titled, Questions Resulting from ACRS Meeting of May 8.
T ra n s-mitted herewith are the original and four copics of a revision to this document dated June 1,1964. The changes are, for th'e most i
part, of a minor editorial naiure with th'e addition of further comments in regard to the filled annulus and an added comment regarding vertical displacements.
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I QUESTIONS RESULTING FROM ACRS MEETING OF MAY 8 l
i Differential Displacement under Reactor i
!i Displac'ement isolation of a structure of this nature, to the writer's knowledge, has no precedent. Consequently, all vital problem areas j
involved must be thoroughly explored and solutions provided as a pre-requisite to acceptance, j
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Accordingly, it is important that the applicant develop a complete pr e-j i
liminary design of a displacement isolation system to accomodate diff-I I
I evential displacements of magnitudes acceptable to the AEC. This i
effort should include complete back-up calculations and drawings, and test data where needed. The scheme should be submit:ed for review, and should be reviewed by one or more authorities in this field, such as Dr. Newmark.
2 The displacement isolation schemes which have been considered utilize t
an annular space between the surface of the excavation and the e=terior-wall of the structure. This space may be open or filled. These schemes involve certain general problem areas involving questions and considerations such as the following:
4 With regard to the open annulus, can a ring wall be designed to prevent i
encroachment on the clearance due to cave-ins before or during an earth-quake?
1' The filled annulus leads to questions relating to the filler material.
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.c (1) The material must be sufficiently compressible and of the necescary thickness to accommodate the. required displacement without locking.
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the other hand it must not be so rigid as to overstress the walls of the
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containment, pata should be provided regarding stress otrain charac-teristics under the anticipated strain rates, including effect of pore water.
. l (2) The material in place must have properties which are. predictable and 1
consistent.
(3) The material must be durable and must' undergo negligible 1
change in properties with time or environmental conditions - A opecific
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question arising here is the effect of ground water, both with regard to the factor of durability and compressibility.
The material preferably should not yield significantly under earthquake vibrations in absence of-differential displacement and should not compact under the weight of the material above.
If there is this possibility, ths thickness, or strength, should be inc reased appropriately. (4) Buoyancy of the material must be 6
properly considered if ground water is present.
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Further questions arise with regard to the integrity of the structure. -If the isolation system contemplates contact of the structure with the rock I
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l wall of the excavation at the shear plane, it should be demonstrated that-the wall can resist the resulting pressures with a reserve ~ margin suffi-i l
cient to permit some further displacement without' violating thc. containment.-
If the isolation scheme contemplated aliding of the structure to accommodate a part of the total displacement, it should be shown that this can occur -
I without violating the containment. If a filled annulus is used, this calculation t
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. should account for the fact that the load along the line contact at the shear plane may be greatly increased due to compression of the fill on the far side.
It is likely that. pressures at the contact will puncture the wall locally before movement of the structure can occur.
In addition to demonstrating integrity of the structure walls, it should be shown that all internal load paths, including those provided by floors and radial walls are adequate to transmit the loads..Where appropriate,
these components should be considered as rings and diaphragms trans-i ferring loads by shear into the outside walls or other resisting elements.
If vertical displacements are considered credible, the annular space provided should be adequate to accommodate tilt of the structure in com-bination with horizontal displacement. The base of the structure and all other features shcald be shown to be adequate for the resulting stresses when combined with stresses from the horizontal displacement.
It is equally as important to be certain that tilt does not lead to internal ma 1-i t
function of the reactor of a hazardous nature.
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If it is found necessary to enlarge the existing excavation, a reasonable I
approach that avoids uncertainties which otherwise could occur would be i
to provide sufficient enlargement to prevent contact between the structure j
and the displaced rock surface under the anticipated displacements.
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gap separating structure and displaced rock ourface should be sufficient to allow some additional displacement without caucing structural damage i
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It should be noted that the cost of an annulus of concrete fill would be something less than $40,000 per foot of thickness, which is not a large price to pay for using this kind of an approach. The cost of additional excavation per foot of thickness in perhaps less certain, and might
. __..._, depend on the inc r ea s e in diamete r.
However, it is doubtful that this cost would exceed the cost of the concrete fill.
It is likely that, at the present time, the applicant has not sized the structural components of the building in final form or determined the i
reirJorcing steel requirem,ents. Hence, in theory, it is not possible at this time to evaluate the effect of stresses due to differential dis-l p la c em en t.
In actual fact, what is desired is not a precise stress ana lysis.
What is needed is an estimate of feasibility to determine a
whether it is possible to resist all forces involved under the hypothetical earthquake and associated displacement, pigs all other concurrent loads, using member sizes, wall thicknesses, and steel percentages which are l
within the realm of reason.
Self Sufficiency of the Reactor Structure and its Internals Particularly where large displacements are considered, the question arises l
regarding the extent to which safety is dependent upon integrity of umbilical features (vital components not supported by the reactor structure but con-nected to it. ) These might include, for example, external water and power I
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of May 8 appeared to indicate that for a period of several hours or more
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the power and water sources within the reactor structure were sufficient' i
without augmentation from outside sources. It seemed to be inferred l
l that the station battery was sufficient to provide all power neede for at least a part of this period. This point needs clarification.
l 1
It is a known fact that auxiliary diesel generator units are not highly j
r e liable. This prompts the question as to whether a backup unit is p rovide d.
It also s'eems a,ppropriate to aok for data regarding the type.
and frequency of maintenance and checkout procedures for such equipment.
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l If integrity of steam and feed water lines under the maximum differential displacement is considered essential from a safety viewpoint, t, hen the.
,,, feasibility of their survival should be supported by rough calculations.
l These would serve to prove or disprove verbal statements previously l
made to the effect that this was not a problem.
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Tsunami Effects i
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j At the meeting of May 8 the problem of damage from tsunamis was argued to be negligible largely on the grounds that the yard elevation of + 25 gav e t
6 protection on the harbor side, and the high bluffs 'gave protection on the t
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ocean side, Nothing was said regarding any special provisions for pro-tecting the intake and discharge features from the effects of tsunamis.
Further elaboration on protection of these features may be warranted, i
depending on how critical they are considered to be from a safety viewpoint.'
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