ML20112G644

Forwards Evaluations from Listed Institutions to Further Substantiate Position Re Soil Structure Interaction Analysis.Existing Info Provides Complete Record for Satisfactorily Closing Issue.Status on Issue Requested

ML20112G644
Person / Time
Site:	Beaver Valley
Issue date:	03/25/1985
From:	Carey J DUQUESNE LIGHT CO.
To:	Knight J, Thompson H Office of Nuclear Reactor Regulation
References
2NRC-5-049, 2NRC-5-49, NUDOCS 8504010188
Download: ML20112G644 (17)

Text

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'Af Duquesne umt m;ee W 2) 92W60 Nuclear Construction Division Telecopy (412) 787-2629 Rr.,Nnson Plaza, Building 2. Suite 210 Pittsburgh, PA 15205 March 25, 1985 United States Nuclear Regulatory Commission Washington, DC 20555 ATTENTION: Mr. Hugh L. Thompson, Jr. , Director Division of Licensing Office of Nuclear Reactor Regulation Mr. James P. Knight, Director Division of Engineering Office of Nuclear Reactor Regulation

SUBJECT:

Beaver Valley Power Station - Unit No. 2 Docket No. 50-412 Soil-Structure Interaction - Additional Information

REFERENCE:

DLC letter 2NRC-5-016, dated February 1, 1985 Gentlemen:

In letter 2NRC-5-016, dated February 1,1985, we provided our response to the NRC Structural and Geotechnical Engineering Branch's (SGEB) Draf t SER open item on Scil-Structure Interaction. DLC's position on this issue, which is stated in detail in that submittal, was discussed with members of the SGEB and Licensing Branch in a telephone conversation on February 12, 1985. In this conversation, the SGEB indicated that their position remains as stated in our November 30, 1984, meeting with them. The SGEB position requires that DLC provide a soil-structure interaction analysis with the free-field ground surface mation applied at the containment structure fo unda t ion level.

However, the SGEB gave no indication as to whether they would address this

! req ues t for information as a backfit as requested by DLC in our February 1, .

1985, submittal.

DLC's position as provided in our February 1,1985, submittal, can be summarized as follows:

The information on soil-structure int eract ion that exists on the BVPS-2 docket provides a complete record fo r the satisfactory closure of this _ issue. Included on the BVPS-2 docket are two tech-nically appr opriate so il-s truct ure interaction analyses (a finite element method analysis and a Kausel-Whitman, three-step me thod analysis) which demo ns trat e that BVPS-2 meets the underlying requirements of SRP 3.7.2.11.4. DIC believes that perfo rming additional soil-s truc tur e interaction analyses using alternat ive methods will provide no meaningful additions to the existing record.

In particular, DLC believes that the analysis requested by the SGEB 8504010188 DR 850325 ADOCK 05000412 h PDR g g u __-

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-.. 'U;it d Stctsu Itclect Rsgulttory Coausission

Mr. Hugh L. Tho pson, Jr. , Director WA + Mr (J ame s . P . Knigh t , Director-Soil-Structure-Interaction . Additional Information

, ;Page ;- 2 would yield results.diich are neither physically representative of the actu'a1.siteiconditions'nor technically appropriate.

To obtain an . addi tional review of our position, DLC has assembled a

> ' panel of L consult ant s' i > evaluate .the . soil-structure. interact ion analyses . that

= have l been docketed J ,fori EVPS-2. . The ~ panel consists of the following

-individuals: .

E.M.KauselhPh.D.(MassachusettsInstituteofTechnology)

J . M. Roesset , Ph.D (University of Texas at Austin)

J; Lysser, Ph.D -(University of California ;at Berkeley)

1. M. Idriss,'Ph.D (Woodward-Clyde Consultants)

'D. E. Shaw, P.E. (Consultant)

C.LW.4Lin, Ph.D (Westinghouse Electric Corporation)

To accomplish the . evaluation, representatives of. . DLC and Stone &

Webster Engineering Corporation (SWEC) met with the panel; members at . SWEC of fices Din .- Boston, MA , on -February 4, 1985. SWEC presented the docketed

x. . soil-scructure interaction analyses _ t6 the panel at that meeting and the panel members were requested; to: provide written evaluations ' based on their review Lof these analyses. These - evaluat ions have been provided and 'are -

attached..

DLC ' believes that c the' attached evaluations further substantiate our 7" position.' We' would again like to ' state our-willingness to meet with the SCEB staf f and appropriate NRC management personnel to clarify any : point s . in this

or ; previous submittals if you feel'such a meeting would facilitate the reso-

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6 .lut ion ' of this - issue. We would appreciate being informed as soon as .possible of- the NRC's status on this issue in order to avoid any unnecessary delays in re' aching a resolution.

.DUQUESNE-LIGHT COMPANY-

-SUBSpIBEDAND WORN TO'BEFORE ME THIS g AY OF ~ ,

d() , 1985.

42) h- M By . /

/m Notary Public yJ . arey Vice cesident

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' - - :d:EiLA LL FATTORE fl0TARY FUSitC s SHiPPIECPSRT Bart0, SEAVE1 COUkTY

- ' MY CCUMISMN EXP!EES SEPT.16,1985 lacmber,Pennsyimia Associatica cf Notnies

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'A t t achment lcc: Dr. W. fKerr, - ACRS (w/a)

- . Dr. D. Okrent, ACRS (w/a)-

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- Dr. C. P. . Siess, ACRS (w/a)

Mr. G. E. Lear, NRC SGEB Chief (w/a)

Mr. B. K..Singh,. Project Manager (w/a)

Mr.; G. Walton, .NRC Res ident Inspector (w/a) p c* .

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[Unitied States Nuclear Regulatory . Commission

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i Mr. Hugh L. Thompson, Jr.,. Director iMr. James P. Knight, Director

Soil-Structure Interaction - Additional Information

.Page 3 COMMONWEALTH OF-PENNSYLVANIA )

) SS:

COUNTY OF BEAVER- )

)

On this [ M day'of g _, ,/ @ [6 , before me, a Notary lPublic in and-for said' Commonwealth and County, personally appeared J. J. Carey, who being duly sworn, deposed and said that (1) he'is Vice President of Duquesne Light, (2) he is duly authorized to execute-and_ file the foregoing Submittal on behalf of said Company, and (3). the statements set forth in the . Submittal are true and correct to the best of his knowledge.

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/ Notary Public

HEllA LL FATTORL Il01ARY PUBUC Sill?PlK; PORT BOE0. BEAVER C0'J'4TY MY COVMlut0N EXPIRES SEPT. IG.193 uen3er, Peerf.nnia Anestica of Em}

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CAussiooE Massachusetts o2:30 Feb. 7,1986 PwCNE 16t7' 253- 5336 Dr. John T. Christian Stone'&WebsterEn@neeringCorp.

245 Sumer St.

Boston, MA 02107- -

Ref.: Seismic Analyses, Beaver Valley 2 Nuclear Power Station

Dear Dr. Christian:

In the course of my work as member of a consulting board to Duquesne .-

Light .Co., I .had the opportunity to review in detail the procedures used by Stone & Webster in the analyses of the Beaver Valley 2 nuclear contain-ment structure for soil-structure interaction effects. This, letter is to give my strongest: endorsement to these analyses. Specifically, the following points.are worth emphasizing:

1)'- It is consistent with current practice and understanding to allow for reductions in the levels of earthquake ground motion in the free field result-ing from wave interference. Such reductions are a necessary corollary of the computational models used, and to ignore or suppress them is tantamount to violations of demonstrable-physical laws.

2) It can also be rigorously demonstrated that an embedded foundation .is subjected to an excitation that differs from the motions that would have been .

observed at that location in the absence of the structure (i.e., in the free field). Such an effect, as you well know, is referred to as Kinematic-Inter-action. Thus, analyses such as Stone & Webster's, which account for this phenomenon, provide a more realistic description of the actual seismic event.

On the other hand. use of the surface motion as input at the base of. the structure is clearly erroneous, and should be vigorously rejected by Stone and Webster. Its use may not only lead to grossly overconservative results at some points in the structure, but to unconservative results at others, especially at higher elevations.

3); A comparison shown to me between the results of a finite element idealiza-tion of the BV2 system and an analysis with a spring and dashpot model (account-ing for kinematic interactions) demonstrated excellent agreement, particularly when consideration is given to the widely different techniques employed. This is, perhaps, the strongest evidence that the analyses performed are beyond re ,

proach.

.x In conclusion..it is my conviction that the soil-structure interaction analyses performed by Stone and Websger conform with current technical stan-dards and state of the art.

S,incerely, s <f /

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y E. Kausel' Assoc. . Prof. of Civil Engineering EK/jm M.I.T., Room 1-271

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l Jose M. Roesset, Sc.D.

Consulting Engineer

- l 11909 Arch Hill Drive Austin, Texas 78750 Dr.- John-T. Christian Stone & Webster Engineering Corporation 245 Summer Street Boston.. Mase. '02107 ,

Dear Dr.-Christian:

, At the request' of Duquesne Light I have reviewed the -

- vario'us documents related to the seismic design and soil structure ,

interaction-analyses of the Beaver Valley Power Station #2, which -

were sent to me by Stone & Webster Engineering Corporation. These documents are: .

1. Attachments A and B to letter, dated February 1, 1985, from E.'J.;Woolever, Duquesne Light Company to U.S. N.R.C. attention-George.W. Knighton.

~ 2. , Sections 3 71 and 3 7 2 of the PSAR for the Beaver Valley Power Station,' unit 2.

l 3 Item 17 of attachment to letter, dated June 15,1984, from '

E.J. Woolever, Duquesne Light Company to U.S. N.R.C. attention George W..Knighton.. I In addition I attended a meeting at the offices of Stone

& Webster.on February 4: 1985,.in which the background history of the analyses and the results obtained from the various models were presented by the Structural Staff of SWEC. Questi'on- on the details'of_the analyses were: asked at the. meeting and answered. by SWEC.

On the basis.of'these documents and the presentation of

-February 4', it is my opinion that the soil structure interaction' analyses ' for' the- containment ' building of the Beaver Valley Power f Station..wnit 2, have been performed in a rational and competent-

- - manner, in e way which is in fact very similar to what I would

,have suggestad or requested myself.

The analyses d'escribed in:the Beaver Valley Power Station unit 2 PSAR were conducted using a two dimensional finite element model with-the program PLAXLY, which is essentially the same as .

FLUSH.- This was for many years the best available state of the -

art 1 technique in engineering practice and it was widely used. The ,

-most significant question that had been raised in relation to the accuracy of this type of solution concerned the two dimensional

' idealization.

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-The.new analyses were aonducted using the three step, substructure or impedance approach using a three dimensional ideali-zation.of the soil'and:the foundation. This is the procedure I

-personally would prefer. A comparison of the results from the two series of analyses indicates good agreement, with the selected

. design' spectra enveloping.both' solutions. This provides a desirable check:on the reasonableness ofLthe results. since different approxi-

- mations wereLinvolved in the two formulati'ons.

I-understand a question has been raised.about the fact'that the= control motion was specified at the fr'ee surface of the soil. ..

This'~is, in my~ opinion, the best approac'h. A concern was raised some. years ago about the fact that the" corresponding, deconvoluted,-

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. -motions at_the foundation level in the free field would exhib i t very sharpmvalleys in their response-spectra ar'ound the natural frequency

- of:the embedment layer. It is important to realize that a) these valleys are not so sharp _when performing a kinematic inter-action analysis and determining the motions at the foundation level

. accounting-for the geometry of the excavation and the stiffness of the foundation, instead of the free field.

b) _'the-foundation motions resulting from kinematic interaction have both a translational and a rotational component. Their combination imay produce higher responses in some cases than direct use of the .

control motion-at the foundation level. There is now mounting evi-

' dence that the: decrease in the high frequency range of the transla-tional motions predicted by theoretical considerations does in fact take place and the use of kinematic-interaction if the most reason-able and realistic approach from a physical point.of_ view as long as both translational and rotational components of motion are included.

c)- the existence of sharp valleys in.the response spectra is elimi-nated if analyses are conducted with logical variations in _the soil properties and the final results are enveloped. This is the approach that was.followed in the analyses for the containment building.

Figure B.4 of attachment B to the letter of February 1,1985, shows clearly that the envelope, design response' spectrum at the base of the' mat has only a very small dgerease over the spectrum of the contro1' motion in the range of 3 to 4 cps and is in fact larger at~

other frequencies. Thus not only is the procedure used correct but by enveloping results for various soil properties safeguards have been introduced to guarantee conservatism.

I do -not find from my review any point I would contest .or any issue that may lead to unrealistic or unconservative results.

Sincerely yours.

f.,./bIh4 7

Jose M. Roesset e

JOHN L_YS M EE R ,, Ph D-Engineering Consultant 1968 Marin Avenue Berkeley, Calffornia 94707

- (415) 521-2615 Files SWE501B/EWS February 8 , 1985 --

Dr. John T. Christian Stone & Webster: Engineering Corporation P.O. Box 2325

-Boston, Mass. 02107 Suh. ject Beaver Valley Power Station - Unit 2 Seismic Soil-Structure Interaction Analysis

Dear Dr. Christian:

At the request of the Duquesne Light Company, I have reviewed Refs. 1, 2 and 3 which relate to the seismic soil-structure interaction analysis of the above plant. On February 4, 1985, I participated in a. full-day-meeting in your offices during which your technical staff presented further details and results of the different analyses, which have been performed for the containment structure of the plant.

I as pleased to' confirm that: I consider your-methods rational and in agreement with the current state of the art of seismic interaction analysis. By your methods, I refer.to the complete finite element analyses perforned by the computer program PLAXLY and the so-called 3-Step Method, including the kinematic

' interaction step. This last step must be included for the method to yield'a proper solution to the equations of motion.

I agree that. the' seismic input motion is best defined at the ground. surface in the free field. This does not conform with the most.recent version, Rev. 1- July 1981, of the U.S. NRC Standard Review Plan, Section.3.7.2, ,I I , Paragraph 4.iii, which specifies that the controlling motion should be specified at the foundation level in the free field. This provision, however, has no rational basis and leads to unrealistic results if applied. A detailed explanation- of this statement is given in Ref. 4. and there appears to be consensus within academic community on this matter.

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You have in my-opinion provided adequate checks on your resultu which also agree- with my experience of how the plant should move if'sub.jected to the specified event.

Sincerely yours, f .

1 John Lysmer Professor of Civil Engineering

Univ. of. Calif., Berkeley

References:

1. ' Attachments - A and B to letter dated February 1, 1985.

From: E. J. Woolever, Duquesne Light Company.

To: U.S._NRC, attention George W. Knighton.

2.. Beaver Valley Power Station - Unit 2 - F.S.A.R.,

Sections 3.7.1 and 3.7.2 ..

3. Item 7 of Attachment to letter dated June 15, 1984.

, From E. J. Woolever, Duquesne Light Company.

To: U.S. NRC, attention George W. Knighton.

4. Seed, H. B., and Lysmer, J., "The Seismic Soil-Structure Interaction Problem for Nuclear Facilities". Appendix to Johnson, J.J., " Sail-Structure Interaction: The Status of Current Analysis Methods and Research - Seismic Safety Margins Research Program". NUREG/CR-1780 or UCRL-53011, Lawrence Livermore Laboratory, January 1981.

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's "i*.cT;?:"" WoodwardiClyde Consultants (7141 835 6886 (213) 581-7164 Te!en 68 3420 ,

15 February 1985

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Dr. John T. Christian Stone & Webster Engineering Corpo.ation 245 Summer Street Boston, Massachusetts 02107 _

Dear Dr. Christian:

As requested by Duquesne Light Company and Stone & Webster, I have reviewed ; documents pertaining to the seismic soil-structure interaction (SSI) considerations for the Beaver Valley Power Station, Unit No. 2. The documents reviewed are the following:

1. Attachments A and B to letter, dated 1 February 1985, from E. J. Woolever, Duquesne Light Company to the USNRC, Attention: George W. Knighton.

2. Sections 3.7.1 and 3.7.2 of the FSAR, Beaver Valley .

Power Station, Unit No. 2.

3. Item 7 of the attachment to letter, dated 15 June 1984, from E. J. Woolever, Duquesne Light Company to the USNRC, Attention: George W. Knighton.

In addition, the results of the SSI analyses for this unit were presented by representatives of the Structural Engi-neering Staff of SWEC at our meeting on 4 February 1985 in Boston. These results covered analyses dating back to 1973-74 and included the most recent analyses completed in 1984.

Based on this review, I find that the SSI analyses completed by SWEC for this power plant are appropriate and are in accordance with the current State of the Art for conducting such analyses. .

Consutting Engineers. Geologists and Envwonmental Scientrsts Offces in Other Pnncipal Cat:es .

Woodward Clyde Consultants Dr.-John T. Christian 15 February 1985 Page 5 In particular, I an in full agreement that the design earth- ,

quake ground motic: s be specified at the finished ground surface and.that kinematic interaction be explicitly incor-porated ir the soil-structure inte raction analyses.

Very;truly yours, ..

Nw. % -

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DONALD E. SHAW, P.E.

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. Export, PA 15632 (412) 327-0051 February 8, 1985 .

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Project No. 84-020-03 Dr. John T. Christian Stone & Webster Engineering Corporation

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Boston, MA 02107 Beaver: Valley-Power Station, Unit 2 Soil-Structure Interaction Analyes Dear Dr. Christians ..

As requested by you and Duquesne Light Company, I have reviewed the material describing the soil-struct'are interaction analyses performed for the Beaver Valley Power Station, Unit 2, (BVPS-2) which you supplied (Refs 1,2,and

3) .- Also, I, along with other. esebers of the Soil-Structure Interaction Assessment Panel met at Stone & Webster Engineering Corporation -(SIEC) offices on February 4, 1985, for a.-presentation of the soil-structure interaction analyses and results.

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. Based en the material provided and the presentation, I find that the analytical methods used fqt the soil-structure interaction analyses of the BVPS-2 containment structure are consistent with generally accepted principles of soil-structure interaction analysis.

1; Specifically, I note the-following points:

1. The Tivee-Step analytical procedure includes kinematic interaction as a method for deriving the. vibratory motion (translational and rotational)

( at the foundation level of-the containment building from the free-field

! ground-surface motion. The use of kinematic interaction is physically appropriate and consistent with well-recognized principles of soil-structura interaction.

Seismic Analysis Earthquake Engineering Structural Dynamics I

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.Dr. John T. Christian February 8, 1985 t

2.

The results of.the Three-Step soil-structure interaction agree very well with the results of the finite-element analyses performed using both the

• Pt.AXLY and F1.USH computer programs. This agreement is expected because the finite element method of- analysis implicitly includes the use of k.nematic interactt.on wnich is explicitly used in the Three-Step method

) of analysis.

- 3. ; l#ille I have I not reviewed the detailed numerical calculations used in -

the Three-Step analyis, the_ procedures _w hich were .used relative to ,

I strain-dependent soil properties, foundation rigidity,. % t effects

- and compliance functions are consistent with my understanding of site p conditions and the structural configuration.

4. Response spectra of the vibratory motion at the foundation level computed by both the Three-Step method and the finite element analyses show the espected " dip" at approximately 2.5 Hz which is the natural frequency of the soil. layer between the ground surface and the base of '

the foundation. This dip in the response spectra is a result of physical phenomena andsis.less than would be.obtained in the free field -

'at the foundation level. By free-field motion at the foundation level I mean that action which is derived by simply deconvoluting the. free-field

ground-surface action without considering geometric effects of the foundation as included in kinematic interaction.

In view of these findings, I believe that the letC request to perfore soil-structure interaction annlyses using the Three-Step method with the free-field ground-surface. time histry applied at the -foundation level is physically inappropriate. It neglects the substantial-body of-evidence which has been generated over the past 15 years which exhaustively, demonstrates that

-the vibratory motion-at depth-is difforent from -the ground-surface action. '

Furthermore, I find that the soil-structure interaction analyses performed for BVPS-2. are consistent with the requirements of 10CFRiOO, Appendix A, as I understand thee, and that the -NRC request would be inconsistent with the regulations.

I might' add that a study which I performed for the P5tC while at DiAppolonia Consulting Engineers and published as NLNtEE/CR-0693 investigated 1thequestion of- where- ter apply- the control motion. It concluded that the

. control motion should be- applied - at the ground surf ace with the motion ~ at the founution level computed based on actual site conditions relative to soil properties and the depth bf the foundation. While the study did not consider the- eHects of foundation geometry .and rigidity as is.done in the kinematic interaction formulation.used intthe Three-Step analysis, the t use-of. kinematic interaction -is a refinement of the methods which wereiconsidered in the study.

_2_

Dr. John T. Christian February 8, 1985 I will be pleased to participate in any meeting with the NRC to clarify

.the above issues and will also be plensed to particpate in any formal

' presentations or hearings on this issue, if required. '

ectfully submitted, 4 _

Donald E. Shaw, P.E.

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DES /saa cc. Mr. Pedro A. Cadena, Duquesne Light Company Mr. Jack Onell, Duquesne Light Company 4

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l Dr. John'T. Christian February 8, 1985 -l l

LIST F REFEREE ES

- 1. Attach e ts A and B to Letter 2NRC-5-016, dated February 1, 1995, from E. J. Woolever, Duquesne Light Company, to U.S. NRC, attention George W.

Knighton.

- 2. Beaver Valley Poseer Station, Unit 2 -

F.S.A.R., Sections 3.7.1 and 3.7.2.

3. Item 7 of Attachment to Letter, dated June 15,' 1984, from E. J.

-Woolever, Duquesne Light. Company, to .U.S. MIC, attention George W.

Knighton.

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EM-CUL-352 Westinghouse Water Reactor Plant Engmeeneg Dmsion Electric Corporation Divisions g 333 PitisDurgh Pennsy:vania 1523C February 11, 1985 Dr. John T. Christian Stone and Webster Engineering Corporation 245 Jummer Street Boston, MA 02210 ..

SUBJECT:

Soil Structure Interaction Advisory Panel Review for BVPS-2 As a panelist of the subject panel, I participated in the review of the soil structure interaction analysis for Beaver Valley Power Station Unit -

No. 2. The review was primarily conducted to address the issue of whether the Kinematic Interaction technique is appropriate for the Unit No. 2 analysis, and whether the technique was properly applied by SWEC.

The objective of the review has been achieved based on the materials provided by the Duquesne Light Company (Refs.1, 2, and 3) publications in tne literature (Refs. 4 and 5), and the presentations made by SWEC -

engineers on February 4,1985.

Alth; ugh only limited detail was made available to the panel concerning the soil structure interaction analyses conducted by SWEC, the following points can be made as a result of this review:

1. When applying the soil spring approach in the soil-structure interaction analysis, free field motion should not be applied at the subgrade (embedment) level.

2. Kinematic interaction provides acceptable estimation to the motions at the subgrade (embedment level). Therefore, it is an acceptable approach in the so-1 structure inter-action analysis.

3. Comparison of the numerical data indicctes that the original finite-element analysis results as described in the BVPS-2 FSAR Section 3.7.2 for containment building are, in general, more conservative than the results obtained by the kinematic interaction approach.

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Cir. ' John T. Christian Februa ry 11, 1985

In conclusion, based on the information presented to me, I feel that Kinematic interaction technique is appropriate for developing the subgrade (embedment) motions in the soil _ structure interaction analysis

- using soil springs. Further, it appears that the results obtained for BVPS-2 using the kinematic interaction technique have shown that the

- original finite element soil structure interaction analysis results are -

conservative and, therefore, should continue to be used in the design and qualification process.

- Very truly yours,

/Yo r l1 C.-W. Lin, Advisory Engineer Engineering Mechanics rin cc: D. A. Bartol J. O'Neil (Duquesne Light Co.)

P. Cadena (Duquesne Light Co.)

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REFERENCES

1. Attachments.A and B to Letter, datedLFebruary 1,1985 from E. J. Woolever, Duquesne Light Co. ,

to U.S. NRC, attention George W. Knighton .

2. . Beaver. Valley

Power Station - Unit 2 - F.S. A.R. Sections 3.7.1 and 3.7.2

3. Item 7 of Attachment to Letter,~ dated June 15, 1984, from.E. J. Woolever, Duquesne Light Co., ~'

to ' U.S. ~ NRC,-~ attention George W. Knighton _

4. - Johnson,-J. J. - Soil-Structure Interaction - The Status of Current Analysis Methods and.Research, Seismic Safety Margins Research Program, NUREG/CR-1780, January 1981.

5. Kausel, E. , et.al. "The Spring Method for Embedded Foundations",

Nuclear Engineering and Design,.48 (1979) 377-392.

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