ML20235Z744
| ML20235Z744 | |
| Person / Time | |
|---|---|
| Site: | 05000000 |
| Issue date: | 03/21/1967 |
| From: | Price H US ATOMIC ENERGY COMMISSION (AEC) |
| To: | Johnson, Nabrit, Seaborg US ATOMIC ENERGY COMMISSION (AEC) |
| Shared Package | |
| ML20235X376 | List:
|
| References | |
| FOIA-87-462 NUDOCS 8710210294 | |
| Download: ML20235Z744 (16) | |
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j l-WR 21 1967 l
NEM02Aurwar IOR (WATEttaa SABORG C0108188103151 JORIISON ColetISS10 LIER NABRIT COIstISSIOMR BAIIEY l
CCIstISSIDIER TAFE SUBJECTS SEISIIIC AID GW10GIC SITIM' AS DESIGIl CRITERIA FOR WCLEAR 70WER PLANTS Attached is the most ressat draf t of Seismie and Geelegic Sating and Design Criteria for Emelear Power Flaats prepared by the regulatory staff with assistance from individuals'la the Coast i;
and Geodette Survey and the Seelegical Survey who' advise the l
staff in.its review of power roaster applicattees.. Staff members from the Divisies of Roseter Development and Techselegy have I
y participated. F1 ease ante that the present draft needs further y%
destga eriteria uhlek are la preparaties by Dr. N. W. 'lloumark work and is incomplete stase it does not as yet feelude.setente l
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Aloe attached is a devoleposat plan and tentative schedule for l
J esoplettag our work en these ertteria.
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(Signed) HLP
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Barold L. Price y
Director of Regulaties gs l;k Attachments:
- 1. Setente and Geelegte Siting and-Design Critaria for Nuclear 7tsver Flaats Draft dated 3/21/67 8710210294 871014
- 2. Sciente Sittag 'and Destga Criteria PDR FDIA Developeest Flam and Schedale SCHADRAB7-462 PDR ses General Itanager (2) beci Clifford K. Beck,.RM 6
offles of the General Counsel (2)'
M. M. Mann, Asst. Dir. for Reactor 0 Secretariat (2)
C. L. Readerson, REG n=. m
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i DRAPI MARCH 21, 1967 AffACHMENT 1 SEISMIC AND GEOLOGIC SITING AND DESIGN CRITERIA PDR NUCLEAR POWER PLANTS Introduction The Atomic Energy Commission has published, in 10 CFR Part 100, " Reactor S te Criteria," statements of factors, including seismologic and geologic i
factors, to be considered when evaluating sites. The specific guidance related to these two particular factors is stated as:
The design for the facility should conform to accepted building codes or standards for areas
.having equivalent earthquake histories. No facility should be located closer than one-fourth mile from the surface location of a i
known active fault.
The regulatory staff evaluates each reactor site proposed in applications for construction permit with respect to seismology and geology. A number of specific factors which are not explicit in Part 100 are of recurrent importance.
It is the purpose of this document to identify these factors and to set forth criteria which will be considered by the staff in future site evaluations.
The criteria are generally of two types:
Criteria defining the natural envirotimental conditions which a.
should be taken into account in the siting and design of nuclear i
power plants for purposes of protecting the public, and l
b.
Criteria defining acceptable engineering methods for designing features important to safety so as to accommodate conditions i
associated with earthquakes.- (The engineering criteria are still under pr'eparation and are not included at this time.)
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Since these criteria are intended for general application, it is to.be expected that.the requirements predicated on a detailed study of a specific site.may vary in detail from the general criteria. The information needed by the Commission in order to be able to determine whether.or not the overall' requirement to protect the health and safety of the public is fulfilled would vary /from case to casa.* accordingly.
It is also anticipated that, in same cases, factors in addition to or different from those implicit in the criteria' may need[ to be considered.
The earthquake criteria have been developed with an appreciation that geophysical science does not provide us at this time with precise information l
about earthquake occurrence and effects. Much of the available information is qualitative, and only in recent years has the quantitative measurement of effects been possible. Too few severe earthquakes have been observed and re-corded to permit reliable estimates of probability of occurrence. In reviewing-l applications for construction permits and in developing these criteria,' it is necessary, therefore, that the best scientific information and technical judgment be utilized so as to avoid any undue risk to health and safety.
In the process of site evaluation, the AEC considers earthquakes and other phenomena that may not have been observed at a proposed site but are known to l
have occurred in a geologically.and seismologically similar environment.
Usually, the disruptive tendencies of unre, severe earthquakes are taken into account in nuclear power plant design than is the general practice in construction of non-nuclear facilities. This rele.tive conservatism is not an absolute guarantee against failure; some risk, however small, n'us't be implicitly accepted.
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.s The criteria dealing with engineering methods are set forth in order to 1
assure that seismic loads are properly applied as design ' conditions to all parts j
l of a. nuclear plant. that are important to safety..The, complexity of the problein j
l of precisely determining response of structures and mechanisas always forces i
approximations which are valid (i.e., conservative) within certain limitations.
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The engineering criteria circumscribe the procedures that may be used in seismic design. analyses in a very general way without prescribing details of procedure.
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Other engineering methods and procedures than those. allowed by these criteria
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could be used, but such use would have to be ' supported by evidence of their.
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validity.
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Criteria Defining the Natural Environmental Conditions for Design
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I.
General Considerations 1
A.
Reactors should be designed in such a way as to avoid undue risk through damage to the reactor and appurtenances resulting from such natural i
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l phenomena as earthquakes, fault movements, and other ground cracking; subsidence; landslides, and other earth movements or failures; floods l
an'd waves; volcanic activity; tilting; an'd changes in physical properties of the naturally occurring materials underlying the site.
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B.
The geologic and seismologic characteristics of the site and'its environs l
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4 II. Seismic Considerations A.
An investigation of seismologic characteristics of the area in which a reactor is to be located must be made to provide specific data for engineering design of the facility. For this purpose, earthquakes of two intensities, designated (1) the " design, earthquake" and (2) the l
" maximum design earthquake," should be determined.
'The " design earthquake" is one vbich can be identified as representing an occurrence that is known from historical reports to have affected the site. It.is usually taken into account in engineering design of a reactor facility as a normal " load" or condition since the. facility should remain functional during and after such an occurrence.
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l The " maximum design earthquake" is one that, from geologic and seismo-logic considerations, is known to have occurred in a similar geologic and
' l seismologic environment in the vicinity in recent geologic times. As a credible occurrence, this earthquake must -be taken into account in engineering design of features important to safety in such a way that it can be reasonably expected that essential safety functions will be main-tained. In particular, the design should be such that, should the
" maximum design earthquake" occur, the reactor could be shut down reliably and consequences-limiting safeguard functions performed at the same time.
B.
Determination of " Design Earthquake" for a Site 1.
The historically reported earthquake resulting in the highest 1l n>
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ij intensity of ground. motion recorded or calculated at a site will be designated thel" design earthquake."* The procedure for determining _
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the " design earthquake" for a site involves:
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Investigation of all historical records #* of earthquakes which <
are known by recorded direct observation to have affected the i
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site or which could reasonably be expected to have affected the site; b.
Re-evaluation by an experienced. seismologist of intens'ities assigned on the Rossi-Forel or Modified Mere'alli-scales;***
c.
For any earthquake for which the intensity at thel site is J
'l not reported, computation of an intensity at the' site front'
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i an empirical equation;**** and 4
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Listing of all earthquakes affecting the site with date of l
occurrence, epicenter or area of maximum intensity, intensity.
.t reported at site (if any), and re-evaluated intensity at site.
- The frequency of occurrence, together with the-geologic characteristics'of-
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the areas affected by each earth, quake, will be' evaluated for each site to determine'whether there are overriding factors which necessitate a different I
definition of the " design earthquake." In particular, geomorphic or other j
evidence suggesting recent seismic activity will be considered as implying-J the occurrence of earthquakes,' even though nons may have been recorded his-torically.
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- Such as " History of United States Earthquakes," " United States Earthquakes,"
scientific journals, and local news publication.
- The historical earthquake data may be found 'in a number of reliable sources; however, seismologists sometimes differ by one unit of intensity in their rating of the higher intensities.
MH**As in B. Gutenberg and C. F. Richter " Earthquake Magnitude, Intensity, Energy, and Acceleration," Bulletin of the Seismological Society of America,
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pp. 32, 163-191, 1942.
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From the compilation of_ all historically recorded earthquakes, the l
" design earthquake" is ' selected as that which resulted in the highest intensity of ground motion at the' site.
C.
Determination of " Maximum Design Earthquake" for a Site 1.
Earthquakes of higher intensity may, by reason of the geologic nature of the region in which a site is located, have sufficiently high~
expectancy of occurrence.that they should be considered as design conditions. Of earthquakes determined through evaluation of geologic information to have such expectancy of occurrence, the one resulting in the highest estimated intensity of ground motion at a site will be designated the " maximum' design earthquake." The pro-cedure for determining the " maximum design earthquake" for a site requires, in addition to the survey, evaluation, and compilation of Section II.B, consideration of:
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The earthquake pattern for the geographical area in which the site is aituated;,and*
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Correlation of the regional earthquake patterns with geologic l
structures to determine the relationship between recorded l
l earthquake epicenters and these features.**
- This area may cover several states as the Appalachian Range and the St. Lawrence Valley.. It.is reccamendedithatsearthquaketmaps;of4 the area, such as ' " United -
States Earthquakes" by. thee Consti and. Geodetic Survey', maps: in scientific journals, and special reports, be examined for the distribution of earthquakes (both high and low intensities). These maps will delineste the earthquake-pattern-for the geographical area which may have a significant influence on determining,their effects on the reactor site.
- In general, most of the epicenters are related to recognized-~ structures, so that their delineation is helpful in rationalizing earthquake potentials in the areas of such structures.
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If an earthquake has occurred'on a geologic structure which passes-through or in the~ vicinity of the site, it is postulated that this carthquake could occur any place along this structure.* Consequently,'
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the intensity at the site of the greatest historically recorded I
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earthquake related to the structure will be computed on the l
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assumption that the epicenter of that earthquake 'is situated at the point on,the structure closest to the site.**
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This procedure (of Section II.C.2) will be followed for each
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structure in the vicinity of the site with which recorded earth-
-l quakes are related (by Section II.C.1).
4.
For faults determined to be active in terms of the criteria cet
'l forth in Section III.D.2, the following procedures will be applied
-l The record of his' oric earthquakes -
in addition to 1,2, and 3 above:
t related to the fault and the length of fault, nature and amount of displacements, geologic history of displacements, and structural relationship of the fault to regional tectonic features as determined from adequate field investigations and the literature will be taken into account. The maximum earthquake that would be necessary to produce the maximum Quaternary structural dislocation along the fault, in terms of the above parameters, will-be determined.***
- Major fault zones which approach within 50 miles of a site may require con-sideration.-
- Consideration will be given to known geologic characteristics of the area I-and the 'aite for evidence that some other intensity would be'more appropriate.
- The magnitude of the maximum earthquake so determined may, in some, cases, be larger by. several orders than the maximum earthquake historically recorded.
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, 5 The " maximum design earthquake">will be that earthquake considered eitherunder2and3orunder5abovewhich'wouldresultinthe highest intensity at the site.
D.
Determination of Ground Motion and Magnitude Corresponding to Earthquake
-Intensities ( of Either " Design Earthquakes" or " Maximum Design Earth- -
Quakes")
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Intensities of " Design Earthquakes" and " Maximum Design Earthquakes" that are not expressed in terms of the maximum ground acceleration of a typical earthquake
- will be converted to those terms through
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correlations of the descriptive intensity scales (Modified Mercalli or Rossi-Forel) with instrumental measurements of ground motion in
'the general area of the site.**-
2.
The magnitude of a " Maximum Design Earthqua'ke" will be determined either directly from instrumental' records of the occurrence (if historical) or fran correlation of magnitudes with the geologic
'j factors considered in Section III.D.
E.
De' termination of the Competency of the Geologic Substrata Under a' Site to Transmit Earthquake Energy to Foundations of Nuclear Plant Structures 1.
The geologic substrata under the sitd 'shall' be examinpa to determine
' their physical characteristics, including seismic velocity, density, and porosity, which' have a bearing on the capacity of the underlying
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- Th'e intensity rating to be used by the designer will be given in' terms of the
. ground acceleration actually measured by a strong motion seismograph multiplied by the factor which will result-in the desired maximum acceleration. - Various seismographic records have been used to specify the shape of the acceleration 1
record.
- If correlations have not been made for a particular area, correlations developed in other areas would be evaluated and applied.
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material to transmit earthquake energy to foundations of the nuclear a
plant structures.;
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In consideration of these known characteristics, values of._an amplification ' factor (which is generally dependent on frequency of -
vibration) will be determined, by which the spectrum of ground' motion j-determined by Section II.D should be multiplied to give. the proper driving forces to' be applied to foundations
- III. ' Geologic Considerations t
A.
Foundation Conditions In addition to determinations of the static and dynamic bearing capacity J
and settlement potential hf the naturally occurring materials underldng the site, evaluations of the following potential problems shall be pro-vided.
1.
Presence of solution phenomena, zones of alteration.of irreguh r-weathering profiles which may impart differential strength para-meters to the foundation mateiials.
2.
Existence of unrelieved residua'l stresses'in' bedrock'at the foundation level.
- In general, for earthquake wave periods of from 0.2-4.0' seconds, sound bedrock
. transmits earthquake energy with less amplification than do less dense superposed deposits such as poorly consolidated sediments,: alluvium or soil; therefore, con-sideration. is given to the physical characteristics of the, geologic, section,,
including seismic velocity, density,_ porosity,Letc. In' evaluating'this amplifi-cation factor, it can be generally aestined that the. earthquake intensity '
experienced and reported at a particular_ location'had experienced the maximum amplification in that geologic environment.' However, caution'should.be exercised in determining insofar as possible that for a particular site there was no exception.
At. the present. time, a number of studies are being conducted to evaluate-amplifi-cation factors for soils. Some of these studies are theoretical and others are.
experimental. :: For the short period. range (0.2-2 seconds) factors of 1 -3 'have been found in a number. of. earthquake investigations, where :simultaneo measurements, were made on bedrock and alluvium.. For the ; longer period. waves 4 seconds), thet amplification may not be as great.
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,1 3 Adverse seismic response characteristics of the foundation materials, including liquefaction, thixotropyf differential compaction and fissuring under maximum potential seismic intensity at the site.
Ground motions and amplification factors determined by the pro-cedures of.Section II will be taken into account in the geological evaluation of the bearing capacity of the naturally occurring material's underlying the site.
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Subsidence due to mining or to fluid addition to or removal from the geologic section underlying or adjacent to the site or uplift due to addition of fluids.
B.
Slope Stability Stability of all slopes, both natural and artificial, the failure of which could adversely affect the site,must be assured.
C.
Flood and Wavec An assessment of the potential effects, both direct and indirect, of the occurrence at the site of the maximum probable flood must be provided.
r An assessment shall be provided of the potential effects, both direct and indirect, of the run-up at the site of the maximum probable wave, either storm, slide, or seismically generated.
D.
Faulting 4
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The siting of the reactor and critical appurtenances must not unduly-4 t
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expose the-structure to damage by surface faulting.* 'In general,'
rupturing of the ground surface by faulting is not a characteristic of earthquakes in eastern United States. 'Nevertheless,:if a fault, il that upon movin6 would.be capable of damaging the structure, exists near or at the. site, the charseterand Cenozoic geologic' history of
' I the geologic terrain containing the site should be ascertained 'in order to' determine the location and character and potential activity; of geologic structures.
West of the Rocky Mountain Front and in Alav1ra and Hawaii, structures which merit investigation are faults longer than'1,000 feet, fla' ult zones (both zones or deformed rock marking l individual faults, and zones of faults) longer than 1,000 feet, and structural discontinuities in the terrain (such as monoclinal flexures)' of similar size.-
2.
A' fault, fault zone, sonoclinal flexure, or other similar' geologic-
- Faults are fractures along which relative displacement (of inches to miles) of-the adjacent-earth materials has occurred parallel to the fracture, and are distinct from slip surfaces of landslides, which are dependent on loca1'topo--
graphy. for their formation.
i Faults and fault zones have a variety of patterns and ' habits. Plan view patterns of faults and zones of faults include:'. single faults with.short or long branches, i
zones of discrete faults in en echelon or other pattern, anastomosing networks; of
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faults, yarious combinations of. these types, and one of the preceding accanpanied t
by lesser separate faults. Plan width of the belt:of' surface fault ruptures lin' a single tectonic event can exceed eight miles, but~ depends on the character of the fault in. question. Other patterns of. fault ruptures, particularly those due-to shallow causes,' may not be simple belts, but may form more complex land/or j
irregular patterns.
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discontinuity shall be considered tectonically active
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one or more of the'following criteria #*
a.
It has been observed and reported to have exhibited seismicity i.
with magnitude.b O or greater; b.
It haa exhibited historic movement based on instrumental measurements '(some faults may at present be revealed-only by-suchmeasurements);
c.
It has moved once in the past 35,000 years;'
d.
It has moved two or more. times. in the past 500,000 years; e.
It is so related structurally to a tectonic structure that is.
active according to criteria a, b, or c, that it can be reasonably inferred that associated activity will occur; f.
It has had sufficiently recent movement to leave perceptible evidence of surface rupture or warping, offset of:surficial siluvium, or offset ch morphologic features (streams, shore-
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lines,etc.).
3 For the purposes of determining its character and extent, each I'
active tectonic structure must be individually investigated.
- An active tectonic structure is one that is currently in operation: creeping, moving rapidly or violently, or lying quiescent between past and future spisodes of actual movement. As so defined, an active fault is one that will move again, but geologists and seismologists cannot. now recognize all'such faults. For the purposes of these procedures, c:titerie a-f for fault activity shall apply.
- Some faults may lack deep-seated, long-term causes, and be due to. shallow short-term causes,t such as volcanic collapse or subsidence. : Valid geologic reasons may exist to demonstrate the future inactivity of such a cause for a particular structure that otherwise would be considered active according to criteria a-f.
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, l Potential genetic relation between structural. features that'are reasonable and not overruled by other geologic factors-shall be 1
. considered.. Outer limits of the fault zone,#. including in all.
l cases all Quaternary traces, shall be delineated from detailed-field investigation and a review of the literature. At no point shall the zone be considered to be narrower than its maximum width'
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neasured along the trend within 25 miles of the site unless.
I definitive. evidence proving a local departure from the characteris-tic habit of the fault system is demonstrated. In some cases, a J
zone of persistent past influence will'not'be applicable, and a-zone of probable influence for a known or reasonably anticipated
- l cause of surface rupture must be used..Once a zone'has.been delineated, the following guidelines'shall be used to establish the distance from the fault thatta: reactor not'specifically ' esigned to d
withstand displacement may be located. In all cases, a reactor not t
specifically designed to withstand displacement shall be located at least one-fourth mile from an active fault.
Maximum design earthquake along the Minimum distance from the zone, as determined under the pro-centerline of the zone a visions of Section II (Magnitude) reactor may be located 4 5 - 5,4
'2/3xwidth**ofthezone 5 5 - 6.4 1 x width of the zone 6 5 - 7.4 lyxwidthofthezone 75+
2 x width of the zone
- In most cases, such fault zones and zones of severe deformation are hundreds to thousands of feet wide.-
- At the point nearest approach to the site.
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If siting of a reactor at less than the minimum distances, ao l-l specified above is contemplated, the facility must' be designed to 1
accommodate safely the following displacements-
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. i Maximum design earthquake along the zone (Magnitude)
Displacement 4.5-55 6 inches 5 6 - 6.5 3 feet I
6.6 - 7 5 18 feet 76+
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- The numbers in this table represent historically recorded displacement for specific events in western United States.
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- i ATTACHMENT 2 SEISMIC SITING AND DESIGN CRITERIA - DEVELOPMENT PLAN AND SCHEDULE j
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1.
Staff development of draft criteria.
Seismological and geological sections - Estimated completion 4/1 I
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b.
Seismic design section - Estimated completion 5/1 '
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Review and comment by ACRS Seismic Subccomittee '- Estimated completion 6/1.
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3 Review and comment 'by joint consultants to Regulatory staff and ACRS Seismic Subcommittee - Estimated ccupletion 7/1
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Review and comment by ACRS - Estimated completion 8/l 5
Approval by Commission of publication of proposed criteria for. public i
comment ~ - Estimated completion 9/1
- 6. Approval by Commission of proposed criteria 'as effective regulation -
Estimatedcompletion1/1/68 l
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