ML19338C023

Review of Seismic Design Criteria for Facility.

ML19338C023
Person / Time
Site:	Midland
Issue date:	02/25/1970
From:	Kast G, Sharpe R JOHN A. BLUME & ASSOCIATES, ENGINEERS
To:
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ML19338C020	List: ML19338C019 ML19338C023
References
NUDOCS 8007310587
Download: ML19338C023 (10)

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, ~ REVIEW '0F THE ~~ SEISMIC ~ DESIGN . CRITERI A -

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. MIDLAND' PLANT (Docket No. 50-329. and 502330)

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REVIEW OF THE SEISMIC DESIGN CRITERI A -

FOR THE MIDLAND PLANT (DocketNo.-5'0M29and.50-330).

This, report summarizes our review of the engineering factors pertinent to the seismic and structural adequacy of the Midland Plant. The plant is located along the south shore of the Tittabawassee River adjacent to the _

Dow Chemical company's main complex in Midland, Michigan.' The design and

construction of 'the plant will be performed by Bechtel Corporation under

, direction of the applicant, Consumers Power Company. The nuclear steam

. supply system will be supplied by-the. Babcock s-Wilcox Company. The plant'will be composed of two units having a combined capability of 1,300- -

.MWe.and 4,050,000 lb/hr.of process steam. The process steam will be sup--

- plied ^to the Dow Chemical Company and the electricity to the appilcant.

Application for.a construction permit has been made to the U. S. Atomic.

Energy Commission (AEC Docket Nos.- 50-329 and 50-330) by Consumers Power Company _. A-Safety Analysis Report _has baen submitted in support of.the application to show that the plant will be designed and constructed in a

- manner which will provide for safe and' reliable operation. Our review is '

based upon the information' presented in the Safety Analysis Report and is <

directed _ specifically:towards an evaluation of the seismic and structur- .

. al design criteria for Class I structures , systems , and components. The

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list of ' referen'ce documents upon which this- review has been based is given -l at the end of this report. ,

DESCRIPTION OF THE FACILITY a

l The~ Midland ~ Plant site is located on a level plain formed by glacial lake

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deposits. _ Elevations vary from about 600 f t to 625 f t above mean sea lev- I el.- Drainage is to the northeast into the Tittabawasse River. The river flows to the" southeast.and coincides with the northeast boundary of the JCHN A. BLUME & ' ASSCCIATES. ENGINEERS t , - n g ,

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' site. The: uppermost solicin..the area is quartz sand which is locally clay-

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' ey and' varies .from O' to _40 f t'in thickness. - Below Lthis ' sand. is a layer of - '7 blue gray clay which in turn is underlain by. sands _and gravels to a total depth of tabout 350,f t. Thece unconsolidated Pleistocene glacial lakeide-N posits' rest.unconformably upon welliconsolidated sediments of Pennsylvania age. The re v. tor and auxi1lary buildings will be-supported'on mat founda-'

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tions,on :the' clay : layers underlying -the uppermost sand. This material var-les f rom stiff .to hard andishould- provide adequateistipport. 0ther major structures will be- founded partly or. entirely upon compacted fill.

--The1 containment structure will be a prestressed concrete cylinder and dome

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,.which will'_be supported'on.a reinforced concrete. foundation slab. The in-

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tert'or of the ' structure will be: lined with a 1/4 . inch thick welded steel' plate.to ensure leak tightness. The -inside . diameter of the containment ._

structure will be'116 ft andLthe Inside height including the dome will be 193.ft.-:The-vertical. wall thickness will'be 3-1/2 ft and the dome thick-ness will#be 3sft. The foundation's1abcthickness will .be 9 f t. The dome and walls ~of the-containment structure wilI be post-tensioned. This post-tensioning. system will consist of three groups of-dome tendons oriented

at;120 'to each other and anchore'd at- the vertical face of the dome- ring-girder;. the' walls _are to be post-tensioned by vertical tendons _ anchored i

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at the ' top surface'of ring. girder _ and at the bottom of the base slab.

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In. addition,? three groups l of h'oop' tendons enclosing 240 - of arc will be anchored at three vertical- buttresses. .

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STRUCTURAL DESIGN CRITERI A AND LOADS

All

structures, equipment,isystems, and piping are classified according

to: function or consequence of_ failure as either- Class 1 or 2 as defined -

in'_~ Appendix 5A' of ;the ' Safety- Analysis _ Report. Class . l . s tructures', sys-tems,-and. equipment"are those whose-failure.could cause uncontrolled re-lease' of ~ radioactivity. orrare

those- essential for immediate and long-term operation following a loss-of-coolant accident. 'They-are designed 5^ _- . JOHN 1 A. BLUME & ASSOCIATES. ENGINEERS 2

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Lto withstand the appropriate seismic loads simultaneously with other

appilcable loads without loss of: function. Class 2 structures, sys- -j tems,1and equipment are those whose failure 1would'not result in.a-7) release of: radioactivity 'and 'would not prevent' reactor shutdown but.

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.may interrupt power. generation.

The design loads for the Midland Plant -are divided -into two basic cate-

. gories. - The first category includes normal operation (dead, live,- and prestress loads)fand the second categ'ory includes accident, seismic ._

and tornado conditions. Structure design loads will !xa increased by

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load factors based on -the probability and conservatism .of the predicted design loads. Yield capacity reduction factors.will tua applied to the stresses allowed.by the appilcable building codes.

ADEQUACY OF THE SEISMIC DESIGN CRITERI A'

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We have reviewed the Preliminary Safety Analysis ~ Report and Amendments

No. I through 8.and have discussed;the various aspects of the seismic design of the plant with the applicant and members of the staff of the '

Division of Reactor Licensing at -a meeting on January 29, 1970. We

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-have comments and reservations regarding the adequacy of the seismic de- -

sign criteria as discussed in the following sections. ,

Comments

.1. The. data submitted by the applicant has included detailed discus-

• sions and analyses of allowable be.pring pressures, settlements in

. founding materials, and the possibility of IIquefaction.

- 2. A detailed discussion of possible ground-su'bsidence due to deep salt

. mining operations'was submitted by the Applicant in Amendment No. 7 Based:on a review of. the analysis and discussion preser'ted by the applicantait appears reasonable to conclude that salt uining activi- )

ties should_ not adversely affect the Midland Plant. However, it

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. JOHN A. BLUME & ASSOCIATES. ENGINEERS' c

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_  ;-; shIould beJnoted thatisome of;the assumpti ns madeIin:the' applicant's 2

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analysis:are;qu'estionable.

Inl particular,Jstress distribution in rock ^ls time dependent and. there- -

. fore the~ adequacy lofEthe.1inear elastic assumption may be questloned. q

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jTheassumedverticaldimensions'of-;the'.cavitiesappear..tobeconser-t

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-vative; however,' the ' lateral Edimensionsicould conceivably be.come much larger -than those assumed. ~Long term m'ining could result'in nearly:

completeiremoval' of f salt from the beds being mined 'over an area some-

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lwhat larger than that. encompassed by the. wells; possibly as large as

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one mile in'dlameter. In addition the'effect of directed stress could result < in preferential solutlon _of those~ portions .of the : salt . bed .

which are under maximum stress.- -

Addltlonalfsafety could be provided by establishing a. system'for. mon-Itoring seismic noise or micro-tremors'and ground surface subsidence

. at the; plant site- and near the salt. mining operations. Such a system could provide sufficient warning to permit a safe shut down of facil-

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ities in. case of ground subsidence even though this possibility may-

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-be;high1y unlikely.

p 3.: 1According to data submitted by.the applicant, there Is no known faul-ting ~n' ear;the site. The nearest fault ng is about-55 miles south of, 8

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the' site ~ consisting of a questionable fault zone which probably trends northwesterly. Other faults are known which are situated 325 miles '

northwest,LandL240'mlies northwest-.of the site. T.he low dipping ,

basement rocks' contain gentle folds but are o.therwise relatively un-disturbed. The condition of..the Paleozoic-basement rocks indicates ,

'that the: region has not been subjected to-significant tectonic activ-tity sincelat? leas.ttthe Paleozoic Era.

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. "Midiand,!MichiganIIs in a seismically quiet area.

$4. Five earthquakes-fare known to have~been centered within 150 miles of the s'Ite, and

.none of these were : felt _ strongly at . Midland. There is no known geo-Llogic control of eabthquake occurrence or distribution. in the' region.

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ThHgreatest historic shocidfelt at Midland "Is' estimated to 'h' ave had .

1 a *MM J intensity V or:withian equivalent : acceleration of about 0.03g.

A'value of 0.06gimaximum ground ' acceleration is postulated for. the 1 J <'

Dssign'f Earthquake and 0.12g :Is postulated for the " Maximum" ' Earth-E

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j quake. lWe' concur. with: the selection of these ground- acceleratio'ns.

. ' However, we-'do not concur- that the response spectra selected for- the .

' site are conservative, las d'scussed under Reservations . in' this re-

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5. - The appilcant' hasistated that he will use the. response spectrum method? _

of dynamic analysis' for Class _ l ' structures, piping, and ~ equipment.

j. The structures'will-be analysed'for response in both the horizontal-

'and vertical directions, and a range of foundation ~ material modull

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L l; will be used In' the analyses 'to. account for variations in these mo-dull.- Time-history analy'ses of Class I structures will be performed' -

L to ' develop . response spectra 'in vertical 'and horizontal di rections at.

the points.of. support'of piping and equipment. -We concur in' general , . .

.withithis a'pproach. ~The analytical. techniques proposed by the-appil -

cant: are satisfr. tory and If properly implemented will result -in a ,

conservative design' with-the' exceptions as discussed under Reserva-

'tlon-In this' report.

j Reservations -

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We have several reservations-about the' proposed seismic design criteria.

These reservations have aris'en because-the appl.icant has.not submitted. -

adequate-information and are as follows: -

f. -1. 1We do not : concur with the conclusion stated 'by the Appilcant in Sec-tion 12.14-1sof' Amendment No.18 ~that vibratory loadings with limited IduratIons /(l'.e.' earthquakes) are. Insufficient to significantly densify

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a thin :sollElayer.'- This conclusion does not take-into' account reported L ,

' instances of densification"of granular ~ solls .during earthquakes. The

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fapplIcant has; indicated 7that soils;with relative,densitles less than

50% willibe' removed and replaced:with compacted = fill having a minimum

'reladseiden'ity.of-75%. s [

In the,a'sence'of any analytical basis Tor.

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' the sbove procedure, i t is our opinion that where ' Class I components

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arel to-be founded upon upper sand layers any sands with relative den-sity less than 75% should be removed and replaced with. compacted fill T having a relative. density of at least 75%. T.-

--. .2.1 :The discussion presented. in Section 5.2.20-1 of Amendment No. 8 refers

. to the work of Seed & Idriss , but. do(s not fully explain how the values i' .

of -Young's Modulus were obtained. They-appear to be too high by about 4 :an order of. magnitude: ~ reference Barkan (1962) 'and the values computed -

by Weston G:ophysical from seismic velocities. Values' computed from. .

seismic velocit!es'are valid at low stress levels and can therefore be . considered to be an upper bound. In summary, we cannot concur that the valu'es of Young's Modulus presented by-the applicant are conserva-l tive.-

. 3 The applicant has not. presented justification that the use.of the pro-

. posed response spectra shown in Figures 5-A-1 and 5-A-2 of the PSAR would be conservative. The use of these curves is not " common prac-tice",:as stated by,the applicant, nor are they conservative. The applicant should either providc' adequate-Justification that the pro-

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posed spectra are conservative for the Midland site' or in 'lleu or pre-senting such justification' modify the criteria, and use spectra as proposed by Newmark and Hall in " Seismic Design Criteria for Nuclear. -

~ Reactor Facilities". In addition if the appilcant chooses to modify .

his criteria, he-should resubmit a comparison of the proposed spectra -

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. and spectri from the time-history of ground motion used for develop-' -

.Ing response spectra at support points of' piping and equipment on Class 1 structures. The applicant should sta'te whether he Intends to utIIIze the proposed' response spectra'for all Class 1 structures, including those placed on the upper sand layers, or whetter the spec-tra will be increased for these areas.

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4. The applicant has proposed to analyse some piping systems for a static load equal to the peak.of.the response spectrum curve at points of 6.-

, JOHN A. St UME & ASSOCIATES. ENGINEERS

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support of'the system in lieu offperforming a dynamic analysis. This

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method wl.11 be used_only when'twice the resulting seismic stresses  !

In? combination with pressure and weight stresses are below the code j

allowable ~ stress. The applicant should provide;a sufficient number

.. of comparisons of- the results of analyses utilizing the proposed static loading approach'andi the results of. dynamic analyses of the-same systems to verify . thee conservativeness of ~ the ' proposed approach.

. 5.  : The applicant has- stated that a Bechtel topical report on engineering ,

methods for seismic analysis will be available on or about March 15

-1970. This report should be submitted for review as soon as it be-comes available.

We consider the ~ resolution of the above items to be essential for approval -

of the seismic design criteria for the Midland Plant.

CONCLUSIONS on the basis of the information presented by the appilcant in the Prell-mint.ry Safety An~alysis Report and Amendments and in oral statements at the meeting, ~and provided that Reservations 'l through 5 above are satis- ~

factorily resolved, it'Is our' opinion. that the seismic design criteria- ,

and~ approach to seismic design as outlined in the PSAR and Amendments 1 through 8, > l.f properly implemented by. the appilcant, will result in a .

f design-that is' adequate to resist the earthquake conditions postulated- -

for.the-site. '

- JOHN ' A. BLUME & ASSOCI ATES, ENGINEERS-

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, ' . JOHN A. BLUME ec ASSOCIATES. ENGINEERS

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" REFERENCES. .j e

Mt DLAND ~ P'LANT.

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CONSUMERS POWER COMPANY .

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Preliminary Safety-Analysis: Report,.~. Volumes ~l,..11, and til

.  : Amendments 1'through 8

Midland Nuclear Site Considerations

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,t . . f;T g o DATE OF DOCUMENT DA ECElvED No.: . - . ,

..-""' John A. Blume Associate ,

.,_ 6 ancisco, California 94105 2-25  ;,-2-70 8"*., _.

LTR. MEM REPORTS OTHLH: ,

Roland L. Sharpe X

To ORIG.s CC: QTH ERs Dr Peter A. Morris 1 signed ACTION NECESSARY CONCURRENCE O o^TzAnswERED NO ACTION NECESSARY O COMMENT O ove CLASSIFs POST OFFICE FILE CODE:

U REo. No, 50-329 50-330 -

DESCRIPTION: (Must Be Unclasssised) REFERRED TO DATE RECEIVED BY DATE Ltr furnishing con:ments on Vol's I,II, A. Dromerick 3-2-7C-III and Acdts 1 thru 8 of the PSAR for v/2 evs for action the Midland Plant and trans:

DISI'RIE7fION!

ENCLOSURESa Regulatory file (Ltr OnAy 50-330)

Report ,, Review of the Seismic Design g, p.,,, g % fe Criteria for the Midland Pland". Morris /Schroeder Boya Levine __

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RETURN TO CENTRAL MAIL ROOM U.S. ATOMIC ENERGY COMMISSION ~ MAIL CONTROL FORM FORM (8arc-3288 60)

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