ML20098A081
| ML20098A081 | |
| Person / Time | |
|---|---|
| Site: | Beaver Valley |
| Issue date: | 09/18/1984 |
| From: | Woolever E DUQUESNE LIGHT CO. |
| To: | Knighton G Office of Nuclear Reactor Regulation |
| References | |
| 2NRC-4-147, NUDOCS 8409240271 | |
| Download: ML20098A081 (7) | |
Text
.
e 2NRC 147 (412) 787-$141 (412)923 -1960 Telecopy (412) 787-2629
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September 18, 1984 Nuclear Construction Division Robinson Plaza, Building 2, Suite 210 Pittsburgh, PA 15205 United States Nuclear Regulatory Commission Wa,hington, DC 20555 ATTENTION:
Mr. George W. Knighton, Chief Licensing Branch 3 Office of Nuclear Reactor Regulation
SUBJECT:
Beaver Valley Power Station - Unit No. 2 Docket No. 50-412 Response to L'eaf t SER Open Item 174 Gentlemen:
The response to the NRC Geotechnical Engineering *;ection's Draf t SER Open Item No.17'+ is provided in Attachment 1. The associated revisions to FSAR Section 2.5.4 are provided in Attachment 2.
DUQUESNE LIGHT COMPANY By E.VJ. Woolever Vice President JD0/wjs Attachments cc:
Ms. M. Ley, Project Manager (w/a)
Mr. E. A. Licitra, Project Manager (w/a)
Mr. G. Walton, NRC Resident Inspector (w/a)
SUB 'CRIBED AND SWORN TO BEFORE ME THIS dDAYOF _M fr/u._ /u
, 1984.
>;b ?h o' W
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Notary Pablic ANITA ELAINE REITER, NOTARY PUBLIC ROBINSON TOWNSHIP, ALLEGHENY COUNTY MY COMMISSION EXPIRES OCTOBER 20,1906 8409240271 840918 PDR ADOCK 05000412
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? Unit:d-StctGs,Nuc1Gcr RIgulctory Cosmicsica F
. Mr;; Gegrg2 W. Knightsn, Chief
-Page 2-C'OMMONWEALTH OF PENNSYLVANIA -).
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SS:
COUNTY OFJALLEGHENY
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On this
/[M : day of
- adwjut,
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, before me, a Notary Public 'in and for said Commonwealth. and County, personally appeared E. 'J..Woolever, who being duly-' sworn, deposed. and seid that (1) he is Vice President ' of Duquesne Light, -(2) he is ' duly authorized to execute and file
- the ' foregoing 1 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.
i d
Notary Public
' ANITA ELAINE REITER, NOTARY PUBLIC ROBINSON TOWNSHIP, ALLEGHENY COUNTY MY COMMISSION EXPIRES OCTOBER 20,1986 t
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.v ATTACHMENT 1 Draft SER Open Item :No. 174 ' (Sections 2.5.4.3.2 and 2.5.4.5) - Foundation data 1 for ? main ' intake structure 'and revised factors of safety for bearing 4
capacity:
ISection 2.5.4.3.2-on reinforced concrete mat All'l Category I structures are founded foundations.. -FSAR Table - 2.5.4.4' gives 'the approximate plan dimen-sions, - the. applied foundation lo.ds, and the ultimate bearing capa-
. city - of. each. foundation.. Table 2.5-1 of this SER gives the plan dimensions, mat ' elevations, and, approximate bearing pressures for '
L the - foundations ; ofl major-Category I structures.
Since the mat foundations are embedded ~ in dense sands and - gravels, the ultimate
. bearing ' capacity is quite high, ranging from 33 ksf for the decon-
~
tamination building = to 129 ksf for the auxiliary building.
The
- calculated static fout.dation stesses range. from 2.5 ksf to 7.5 ksf -
the upper value being the foundation pressure ' beneath the Reactor Containment Building.
Therefore, the factor of safety against a.
1 bearing capacity-failure is: typically very high.
In response.to OL question 241.9, the appilcant has informally furnished a revised copy 'o/ FSAR Table 2.5.4-4 incorporating the dynamic foundation loads therein. The - foundation stresses including the effects of dynamic loads range from 3.8 ksf ' to 12.4 ks f.
- The applicant has not revised the factors of safety. shown in that table, although the proposed revision should-not alter 'the above conclu-sions regarding-the high safety factors against; a bearing capacity fallure.- The. applicant is expected to docket the revised FSAR Table
-2.5.4-4 with corrected safety factors.
m"
. The information concerning the foundation dimensions and the bearing espacity of' th'e main' intake. structure are not ' included. in Table L
3.5.4-4.
The applicant has been requested to include the foundation
- c.ata concerning the intake structure in revised ' FSAR Table 2.5.4-4.
~
Section 2.5.4.5
~ The major. items that need to. be addressed by th'e applicant in the forthcoming amendment of the FSAR are the following:
...6.
Docket the revised FSAR Table 2.5.4-4, including therein the corrected' dynamic soil - pressures and factors of safety
.against. bearing capacity-failure ' and also incorporating the 4
data concerning the foundation for. the main intake structure; Response:=
- Refer.to revised FSAR Secticn 2.5.4.10.1 and revised FSAR Table 2.5.4-4 (Attachment 2). These revisions will be incorporated into FSAR Amendment 9.
b.
ATTACHMENT 2 BVPS-2 FSAR 2.5.4.10 Static Stability Foundation analyses related to the static stability of Category I structures included -evaluation of bearing capacity, estimate of settlement, and the development of design lateral earth pressure
. parameters.
2.5.4.10.1 Bearing Capacity All Category I structures are founded on mat foundations. The design of mat foundations, particularly those on dense sands and gravels, is generally limited by a consideration of maximum tolerable settlements rather than by ultimate bearing capacity, since the factor of safety against a bearing capacity type failure is typically quite high.
Estimated static settlements of plant structures are presented in Section 2.5.4.10.2.
However, for completeness, the bearing capacity of the foundations of Category I structures and the factors of safety against a bearing capacity type failure have been computed and are g#c be % stadic A d L
presented in Table 2.5.4-4.
clPwwi leang the ultimate bearing capacity of the supporting soil is a function of cag;fions the soil properties, the size and shape of the foundation, the depth of embe hent and the depth to the ground-water table. The equation bearing capacity iss' used for computing ultimateish.fic.
Square or rectangular footings:
ht " #c
+ 0.3 f
+ ym + 0,4 y g q
circular footings: radius = R F
h t = 1.3cN
+T q + 0.6YBN c
t (2.5.4-11) where:
q it ultimate bearing capacity
=
i u
cohesion e
=
depth to base of mat foundation D
=
unit weight of soil y
=
width of foundation B
=
length of foundation L
=
bearing capacity factors N,N,N
=
c q s
2.5.4-22
i 1:
i BVPS-2 FSAR The following assumptions were made in computing the bearing eapacity:
utfimafc SfecN(
1.
Each structure was considered individually, ignoring increases in confinement due to adjacent structures.
2.
Each structure was assumed to be founded on the in situ sand and gravel with the following properties:
30' friction angle
=
=
0 cohesion 125 pcf above unit weight
=
ground-water table 136 pcf below
=
'9 ground water table 3.
The ground-water table was taken as that corresponding to probable max'imum flood conditions at el 730 feet.
As discussed in Section 2.5.4.7, a portion of the safeguards area and the RWST is underlain by a layer of stiff silty clay with a top' i
surface at approximately el 688 feet. Soil profiles depicting the on Figures 2.5.4-8 conditions underlying these structures are shown and 2.5.4-9.
This stiff clay was not considered to be a concern to the stability of the structure insofar as a bearing capacity failure L
is concerned due to the thickness of the overlying compacted i ~s structural fill. The bearing capacities given in Table 2.5.4-4 for
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the safeguards area.and the RWST were computed for their respective foundations on compacted fill with the preceding assumptions.
- Z uerf 'A,
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[pg 2,s.4 13 cw) 2.5.4.10.2 Settlement This section discusses the estimation of the total static settlement of the plant structures; the estimation of dynamic settlement during a seismic event is discussed in Section 2.5.4.8.2.
A summary of the estimated total static settlements of the plant structures is provided on Figure 2.5.4-20.
Differential settlement between structures was taken as the difference between the estimated total static settlement of the respective structures.
Observed settlements as of January 1, 1983 are shown on Figure 2.5.4-46.
l Foundation soils in the main plant area consist of compacted select granular fill and medium dense to dense in situ granular soils.
The northern portions of the safeguards area and RWST are underlain by a layer of stiff silty clay.as discussed in Section 2.5.4.7.
Site subsurface-profiles within the plant area are shown on Figures 2.5.4-2 through 2.5.4-9.
The ground-water level was assumed to coincide with normal river level at el 665 feet.
Amendment 6 2.5.4-23 April 1984 i
g Insert "A" The ' ultimate static bearing capacity was also used as the ultimate dynamic bearing capacity when computing the factor of safety against a bearing capac-ity-failure for dynamic loading conditions.
The ultimate dynamic bearing capacity 'is conservatively cepresented by the computed ultimate static bearing capacity.. Tests reported by Vesic et al. (1965) for both dry and saturated dense sands, performed at various loading rates, showed a slight drop in bearing capacity with increased loading rate, followed by a steady slow increase. The observed minimum dynamic bearing capacities were about 30 percent Iower than the static bearing capacities, which corresponds to a 2
. degree decrease in the angle of internal fric tion.
The in situ sands and gravels at the BVPS-2 site have ' an internal friction angle which ranges between 33. and 40 degrees (see Section 2.5.4.2), while a 30 degree value was conservatively chosen for design purposes. Since a 2 degree reduction in the actual minimum internal friction angle of the in situ soils would still be higher than the friction angle used for design, the actual dynamic bearing capacity is higher than the computed static bearing capacity shown in Table 2.5.4-4.
Therefore, the ultimate dynamic bearing capacity is conservatively represented by the computed ultimate static bearing capacity.
Reference Vesic, A.S., Banks, D.C, and Woodward, J.M., 1965.
An Experimental Study of Dynanic Bearing Capacity of Footings on Sand, Proceedings, Sixth Inter-national Conference on Soil Mechanics and Foundation Engineering, Mont re al,
Canada, Vol. II, pp 209-213.
2.5.4-23a
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SVPS-2 FSAR 1A8tE 2.5.4-4 gggg SEARil6G CAPACITY - CATECORY I SIRUCIURESST AtTt t-Appronimatet-pgg Approximate Approvisato ultimate Approwsmate-BWumedse g
i Dimensions or Foundation Bearing
- semede, factne
{
Contact Area Depth Capacity good nr load sarntv t h D_.
trei artl Iksrl
_t hW___
32 10.6 IS~
120 x 146 32 129 5.7 Auxillary building 65 x 81 32 W Ty 3,5 gy g4 56 25 31.5 3
33 x 33 5.5 33 6.3 4 5-Control room extensinn 10.9 3
e Decontamination tsuildinj 7"5 Ar.7 M _W 3.ta y go pf s,.,
5.9 Demineralized wates tasi
- 38 x 40 22 go 3,g' 8.4 o
83 x 83 l(s Diesel generator besoldiseg
~22 3 x 30 set 25 et 60 y.I Emergency outrall structure 17.7 61 6.3 Il 11.5 6
uee t hesi ld ing 90 x 135 22.5 mg 3,y pg 7.1 Q
I.4 x llo Main steam and cable vaasit 142 dia.
54 157 7.5 36 12.4 g7 8.8 Reactor containecot 55 ha v Q M 4.7 44 3.5 isr g3 -
8.7 8
Rnfueling water stpenge tank 60 x 96 70.5 -
76 3.2 35 Safeguards area 9.5 54 4.0 IS 4.6 Service bulloisig 23 x 35 18.8 50 2.5 33 3.8 37 55 x 186 Valve pit une m.c us
- s. e n
s.,
u l
-g;;~a n a ground-water level at el 730 feet corresponding to PHI l
include Atmyant ef fect or water p
)'
- foundation load does not
-a,.,e e iam -
hCPre l imisue s, data,structesses not rtelly designat g=$ cArity c tatata.5sy;)
UIncludes bVeyso.ty APri8 39#'8 1 of 1 Amendment 6
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