ML20234D809

Responds to NRC 870728 Request for Addl Info Re Bldg 10, Including Descriptive Matl for PILAY2 Computer Code & Sketches or Drawings of Caisson/Slab/Wall Configurations. Sketch of Configuration & Wall Stiffness Calculation Encl

ML20234D809
Person / Time
Site:	Fort Saint Vrain
Issue date:	09/09/1987
From:	Warembourg D PUBLIC SERVICE CO. OF COLORADO
To:	Calvo J NRC OFFICE OF ADMINISTRATION & RESOURCES MANAGEMENT (ARM), Office of Nuclear Reactor Regulation
References
P-87316, TAC-55287, NUDOCS 8709220199
Download: ML20234D809 (6)

Text

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==;a 0 Public Service- ,

0 2420.W. 26th Avenue, Suite 1000, Denver, Colorado .80211' {

1 September 9, 1987 Fort St'. Vrain.

Unit No. 1 P-87316

'U. S. Nuclear Regulatory Commission i ATTN: Document Control Desk Washington, D.C. 20555 Attention: Mr. Jose A. Calvo l Director, Project Directorate IV Docket No. 50-267-

SUBJECT:

Request for Additional Information'on FSV Building 10

REFERENCES:

1)NRCLetter,l.Heitner l ~ to Williams, dated l

7/28/87,(G-87255)-

2)Telecon,PSC'(Goss).

and Stone & Webster (Rodell) to NRC ,

(Heitner)and Brookhaven National' Laboratory (Miller) on 8/13/87

3) PSC Letter, Lee to Hunter, dated 8/23/85,. (P-85298)  ;

Dear Mr. Calvo:

This letter responds to the request for additional information related to Fort St. Vrain Building 10,. posed in Reference 1. The requested additional information as stated in Reference 1, along with PSC's response, is listed below.

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P-87316 Page 2 September 9, 1987 ITEM 1 NRC REQUEST Reference is made to the computer code PILAY2. Please provide descriptive material for this code. .If the computer code generates frequency dependent interaction coefficients, a plot of the stiffness and damping interaction coefficients as a function of frequency should be provided.

1 PSC RESPONSE PILAY2 is a. computer program developed by Systems. Analysis Control and Design Activities, The University o.' Western Ontario, under the direction of Professor M. Novak. The program calculates the stiffness and damping coefficients and interni:.1 forces and displacements of a single vertical pile embedded :n layered soil media for all vibration modes including torsion.

The program is based on a theoretical model that derives the soil reactions from a continuum and represents the pile by finite elements. The model is approximate but -incorporates the variation of soil properties with depth, imperfect fixity of the pile tip, material damping of soil, and effects of slippage an6 nonlinearity. The following assumptions and limitations a ', e associated with the use of PILAY2:

Assumptions

1. The pile is vertical, linearly elastic, and its material damping is included.

2. The pile is of a circular cross section.

3. The cross section of the pile can be constant or stepwise variable.

4. The head of pile can be either fixed or pinned.

5. A portion of pile can be freestanding above ground. I

6. The pile is perfectly bonded to the soil. Pile separation can be accounted for by considering the adjacent layer of soil as' void.

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1 P-87316

-Page 3

. September 9, 1987-

7. The soil is linearly elastic, and its properties can be different in each horizontal layer,

8. If the soil deposit is homogeneous,.its stiffness can vary 4 in a continuous manner due to the continuous increase in-confining pressure (Parabolic Distribution).

9. With rigid bodies, the soil underneath' the base can be layered and its stiffness within the soil column under the base can be different from that outside the column in each layer.

10. 'A zone of cylindrical cross section around the pile can be accounted for in which the soil parameters differ from those ,

of the outer region (Composite media).

Limitations

1. Maximum number of soil layers is 30.

2. Single vertical pile.

3. Circular solid pile.

4. Number of frequencies which can be solved at one time is 10.

l 5. Units of input and output can be any. acceptable system as long as they are consistent.  ;

6. Weakened zone for Rigid-Body analysis is limited only to the zone next to the footing.

As was discussed in Reference 2, although the PILAY2 code is capable of generating frequency dependent interaction coefficients, PSC does not deem this warranted or cost effective and hence this function has not been performed.

ITEM 2 NRC REQUEST Sketches or drawings should be provided showing the caisson / slab / wall configurations upon which Public Service

! Company of Colorado concluded that the foundation system is two to four times stiffer than the caissons.

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September 9,i1987; 1 1

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PSC RESPONSE-i Figure' 1 Jis a' sketch .ofy the . Building.10 caisson / wall '!

configuration. The' base slab ^1s l'-0". thick with ' grade . beams

' spanning ~ between' adjacent piles? .This information.is also shown' 1

.in detail on the Public' Service LCompany drawings'.which were- 1 previously submitted!in response. to Litem 1.of. Reference 3.

A calculation- is provided . as. Attachment 'I which numer'ically

demonstrates .that 'the relative stiffness of the wall'fsyst'em is

^two to four.timesLthat of the' caissons..

I'fyou have anyLquestions concerning this subject, please' contact Mr. M.H.~ Holmes at . (303) 480-6960.

'Very truly.yours,

$$ $nus

-D. W. Warembourg, M ger Nuclear Engineering 1 Division DWW/MM:pa Attachment ~

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to P-87316' Comparison of Wall to Caisson Stiffnesses

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-The stiffness of .these systems ' is _ determined . by' the moments of ]

inertia. The moment. of inertia of the wall, system is ' calculated - ,

considering- the width .and the height- o f- .the wall. The caisson- j stiffness is calculated considering the areas of the caisson and the- '

distance from the neutral axis. Figure 1 depicts the Building:.10 wall a'nd caisson configuration.-

The moment of inertia of the wall is: determined by the _ equation:

I = bd /12 where b = width of wall = 1'0" d = depth of wall = 63'0" j i

Therefore, for-the building 10 wall system (neglecting the moment of j

. inertia of the grade slab and grade beams): j 1.0'-(63.0')3 ._, 4.17 X 104 FT4 I=2 12 j The moment -of inertia of the caisson system is determined by the equation:

2 I =S Ad where A = area of caisson ~= 12.57 ft 2 q d = distance from neutral axis .

= 14'6" for N-S axis l

= 20'-0" for E-W axis 1

Therefore, for the Building 10 caisson system:

I =

6 (12.57 FT2 ) (14.5 FT) 2 = 1.59 X- 10 4 FT4 N-S I =

4 (12.57 FT ) (20.0 Fd = 2.01 X 10 4 FT 4

E-W As demonstrated above, the inertia of the wall system falls within the previously stated range of two to four times that of the caissans. 1

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