ML20215M820
| ML20215M820 | |
| Person / Time | |
|---|---|
| Site: | Beaver Valley |
| Issue date: | 10/23/1986 |
| From: | Carey J DUQUESNE LIGHT CO. |
| To: | Harold Denton, Tam P Office of Nuclear Reactor Regulation |
| References | |
| 2NRC-6-111, NUDOCS 8611030325 | |
| Download: ML20215M820 (20) | |
Text
'Af g
2NRC-6-111 Beaver Valley No. 2 Unit Project Organization Telecopy 2) 3-52 Ext.160 f,h, soxi2$"8 8
Oct. 23, 1986 Shippingport, PA 15077 Mr. Harold R. Denton, Director Office of Nuclear Reactor Regulation United States Nuclear Regulatory Commission Washington, DC 20555 ATTENTION: Mr. Peter Tam, Project Manager Division of PWR Licensing - A Office of Nuclear Reactor Regulation
SUBJECT:
Beaver Valley Power Station - Unit No. 2 Docket No. 50-412 Response to SER Confirmatory Item 2 Gentlemen: provides a partial response to SER Confirmatory Item 2 (Differential Settlements of Buried Pipes). The revisions to FSAR Section 2.5.4 that are associated with this response are provided in Attachment 2.
The remainder of this response will be provided at a later date.
DUQUESNE LIGHT COMPANY I
By JY J. @ rey Sr. Vice President JD0/ijr NR/CONFRM/ITM/2 At nts AR NAR cc:
Mr. J. Beall, Sr. Resident Inspector - w/ attachments Mr. L. Prividy, Resident Inspector
- w/ attachments INPO Records Center
- w/ attachments NRC Document Control Desk
- w/ attachments
%ioggDC D
I l
E ll
United States Nuclear Regulatory Commission Mr. Harold R. Denton, Director Response to SER Confirmatory item 2 Page 2 COMMONWEALTH OF PENNSYLVANIA )
)
SS:
COUNTY OF BEAVER
)
On this [ [ day of MM61]
/
, before me, a Notary Public 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.
lYk')
$lt??/
./
Notary Public sNfRA N. FAUCRE 40iARY PUBUC SN!PPINGPORT 8080, EEAVER COUm MY COMulS$10R EIPIRES OCT. 23.1989 "wbu. Pucsylvania Association of Notaries
)
1
ATTACHMENT 1 SER Confirmatory Item 2 (SER Sections 2.5.4.3.3 and 2.5.4.5) -
Differential Settlements of Buried Pipes:
Part 1 From SER Section 2.5.4.3.3, Page 2-51:
Although the applicant is monitoring the settlements of all seismic Category I structures, as stated above, there is no program to mon-itor the settlement of buried pipelines.
Because the pipelines have been buried in the soil without the instrumentation for settlement monitoring, the applicant will demonstrate the safety of buried pipes against the effects of differenti al settlements by an analytical evaluation of the expected differential movements of buried pipes to determine if the pipes are capable of withstanding such differential movements without exceeding the allowable pipe stresses.
Such an analytical evaluation and demonstration of the adequacy of the buried pipelines against the effects of differenti al settlements is an acceptable alternative to settlement monitoring of buried pipes.
From SER Section 2.5.4.5, Page 2-54:
The staff reviewed the applicant's design criteria and the results of the applicant's field investigations, l abor atory tests, and engineering analyses in accordance with SRP 2.5.4 and concluded that the plant foundations will safely support the seismic Category I structures and systems.
This conclusion is subject to the applicant's furnishing a confirmatory analytical evaluation to demonstrate the adequacy of buried pipes to withstand the effects of differential settlements.
The analysis is expected by early 1986.
Part 2 From SER.iection 2.5.4.3.3, Page 2-51:
Longitudinal sections of pipelines (shown in FSAR Figures 2.5.4-52 and 2.5.4-54 and discussed in response to Question 241.2) indicate a considerable thickness of silty clay directly below compacted gran-ular backfill.
Also, as seen in FSAR Figure 2.5.4-54, a steep gra-dient exists in the embankment slope that contains the 30-inch-diameter-pipelines from the present floodplain to the main plant area.
These conditions can cause differential settlements of the overlying pipelines.
The applicant has been asked to evaluate this differential settlement and include the results in an FSAR amendment; the staff regards this as a confirmatory item.
. = _.
Response
Part 1 The method used for detennining the adequacy of buried piping to withstand the effects of differential settlements is described in the revisions to FSAR Section 2.5.4 provided in Attachment 2.
These revisons will be incorporated into a future FSAR Anendment.
Any related analyses will be informally provided to the NRC upon request.
Part 2 i
The response to this part will be provided at a later date.
f-1 t
3
)
6 i
i e
i l
l
ATTACHMENT 2 BVPS-2 FSAR Replace. w:h hsed. n A
(Pag e 1. 5.+ - 246 )
2.5.4.10.2 Settlement
[This section discusses the estimation of the total static settleme d of the plant structures; the estimation of dynamic settlement during ta seismic event is discussed in Section 2.5.4.8.2.
A summary of the estimated tota) static settlements of the plant structures is provided on Figure 2.5.4-20.
/ Differential. settlement R "
structureswastakenasthedifferencebetweentheestimated]j
[between Ltotal static settlement of the respective structures.,r' Observed' settlements as of January 1, 194 are shown on Figure 2.5.4-46.
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 RHST 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.
Total static settlement of the plant structures founded on granular soils was assumed to consist of two components:
an elastic component and a time-dependent component which was assumed to be equal in magnitude to the elastic component (Swiger 1974).
The elastic settlement of the structures in the main plant area was calculated using the computer program SETTLE II (Jubenville 1976).
This program computes the elastica 11y distributed stress with depth and computes the compression of each layer in the soil profile beneath a selected point on a given structure due to the load imposed on the soil by that structure along with any adjacent structures.
The stresses induced by the loaded areac can be calculated using either Boussinesq or Westergaard solutions; the Boussinesq solution was used in this analysis. The foundation configurations, structural loads, and founding elevations of the plant structures are shown on Figure 2.5.4-41.
Certain assumptions accompany the use of SETTLE II in determining settlement.
These are: 1) the load imposed by a structure was placed instantaneously, 2) the loads on all structures were placed simultaneously, and 3) settlements occurred simultaneously with load application.
In calculating settlement, the program sums the vertical strains between the founding elevation and the top of the rock according to Equation 2.5.4-12:
Amendment 9 2.5.4-24 December 1984
BUPS-2 FSAR
[
z n
fc dz=[
i i~
p =
y i
(2.5.4-12) where:
o i=1 d
elastic settlement p
=
total thickness of soil z
=
vertical strain c
=
v number of soil layers n
=
Aqf stress increase at center of layer i due to
=
foundation loading y
thickness of layer i Az
=
g constrained modulus of layer i D
=
The constrained modulus was calculated according to the equation:
E.
(1-u) 1 D.
=
1 (1+p) (1-2u)
(2.5.4-13) l Amendment 9 2.5.4-24a December 1984
Insert "A" This section describes the calculation procedure used to estimate the static settlenent of selected points on plant structures..The same pro-cedure is used to estimate a profile of settlement along buried, safety-related piping that extends from the structures out into the yard.
The settlement profile is used to evaluate stresses imposed on the piping system using procedures described in Section 3.78.3.12.3.
This section also decribes the calculation procedure used to estimate the differential settlements between the closely spaced main plant area structures that are used for pipe stress analysis.
Dynamic settlements during a seismic event are discussed in Section 2.b.4.8.2.
2.5.4-24b I
l I
l
.. _, _.. ~, _.. _...,.,. -,,., _.. -,. _ _ _....,, _ -.
U 1[OJ o C
BVPS-2 FSAR where:
Ei Young's modulus of layer i
=
Poisson's ratio = 0.3
=
y To account for the change in constrained modulus that occurs with changes in effective stress as construction continues and additional load is applied, an average value of constrained modulus was used to estimate the elastic settlement.
Typically, an initial value of constrained modulus was computed based on the in situ stress conditions after excavation but before the structural loads were applied.
SETTLE II was then used to determine the change in stresses at the center of each layer due to structural loads (including loads imposed by adjacent structures).
Using these stress changes, values of the final constrained modulus
'ere determined for each layer.
w Average values of the initial and final constrained moduli were then used in SETTLE II to calculate the settlement of the structures.
Young's modulus was determined by Equation 2.5.4-14:
E = 2G(1 + p)
(2.5.4-14) where E
=
Young's modulus Shear modulus G
=
Poisson's ratio U
=
Low strain shear moduli were estimated using the following Hardin and Black equation (Hardin and Drenevich 1972):
1,230 (2.97-e)2 (
)0.5 G=
(1 + e)
(2.5.4-15) where shear modulus (psi)
G
=
void ratio e
=
effective octahedral stress (psi) o
=
o Shear moduli determined from in situ seismic velocity measurements compared quite favorably with those computed using the Hardin and Black equation as shown on Figure 2.5.4-12.
Standard penetration test N values in the densified zone showed a marked increase after densification as compared to before (DLC 1976).
However, in situ seismic velocity measurements that were made after densification do
~
not show the same marked increase (Figure 2.5.4-18), suggesting that the elastic properties of the densified zone are similiar to those of 2.5.4-25
C$syts b $
ny.
f the naturally dense in situ soil.
Consequently, for the purpose of computing elastic properties for use in the analysis of settlement, no differentiation was made between soils within and outside the densified zone.
The value of low strain shear modulus was reduced by a factor of three to account for the reduction of shear modulus with strain (Swiger 1974).
The settlement of isolated structures outside of the BVPS-2 main plant area were calculated manually using published elastic solutions generally of the form (Poulos and Davis 1974):
= IPS p
E (2.5.4-16) where:
elastic settlement 0
=
influence factor which accounts for the I
=
shape of the loaded area and the position of the point for which settlement is calculated foundation loading
=
p che.racteristic dimension of structure B
=
Young's modulus E
=
As with the analysis of settlement using the computer program SETTLE II, the value of moduli used was the average of the moduli determined for the initial and final stress conditions.
The settlement of the clay layer underlying the northern portion of the safeguards and the RWST was analyzed using one-dimensional consolidation theory.
The estimated total settlement included both j
the clay layer consolidation and the elastic settlement of the in situ sand and compacted fill computed using SETTLE II.
The properties of the stiff silty clay layer for use in the settlement analysis were developed from consolidation tests presented in Appendix 2.5D.
The active and passive earth pressure coefficients were computed for the case of a vertical wall, horizontal backfill, and no soil / wall friction according to the Rankine equations (Bowles 1977):
2.5.4-26
I BVPS-2 FSAR K
=
tana (45 - f/2) a K
=
tana (45 + f/2) p where:
a coefficient of active earth pressure K
=
coefficient of passive earth pressure K
=
&p effectiva friction angle of soil
=
For the in situ sands and gravels, the coefficient of lateral earth pressure at rest, Ko, was computed from the equation (Bowles 1977):
l-sini
= 0.5 (2.5.4-17)
K
=
g The value of Ko for compacted select granular fill used for design was 0.6, which is larger than that. which would be obtained from Equation 2.5.4-17, and was selected to account for the increase in lateral earth pressure due to compa; tion.
The calculated
- active, passive, and at-rest earth pressure q
coefficients for the in situ sands and the compacted select granular J
fill are given in Table 2.5.4-5.
No safety factors have been applied k
to the coefficients presented.
4-q.
Equations for determining the static and dynamic lateral earth and g
.. water pressure distributions against unyielding walls are shown on Figure 2.5.4-42.
Lateral earth pressures due to horizontal and vertical ground accelerations were determined according to the
\\q analysis developed by Monabe-Okabe and described by Seed and Whitman a
(1970).
These procedures were used for all Category I plant
[
structures except the reactor containment which was analyzed 4
acccrding to the procedures given in Section 2.6.5.4 of the BVPS-2 L
PSAR (DLC 1972g).
N h
Design basis for structure hydrostatic loading is discussed in Section 2.4.13.5.
2.5.4.11 Design Criteria State-of-the-art methods were used in the analysis of foundation stability of Category I structures. Methods used to evaluate bearing
- capacity, settlement, and lateral earth pressure are discussed in Section 2.5.4.10.
The liquefaction potential and an estimate of the dynamic settlement of the granular soils at the site are discussed in Section 2.5.4.8.
Soil properties used in the analyses are provided in Sections 2.5.4.2 and 2.5.4.5.
Minimum design factors of safety are as follows:
Bearing capacity 3.0 for all loading conditions.
2.5.4-27
~
Insert "B" The differential settlements for safety-related piping that spans the shake spaces between adjacent main plant area structures are estimated by using the settlement data obtained from the settlement monitoring program described in Section 2.5.4.13.
The observed settlement data is used to make a prediction of the total settlement of the two adjacent structures that are penetrated by the pipe.
An average line is drawn through the log-time plots of observed settlement and extrapolated over an assumed 40-year plant life. The total settlement at the end of 40 years is reduced by the settlement that occurred prior to the date of the final weld connecting the pipe to the structures.
Since settlement markers are typically not located at piping penetrations, it is necesary to interpolate between adjacent markers to estimate the total settlement at the penetration.
The differential settlement of the pipe is the difference between the total settlements of the two adjacent structures at the piping penetration points subsequent to the final weld.
An analysis is made of the stresses imposed on the piping system by this differential movement.
For the purpose of pipe stress analysis, a minimum differential settlement of 0.5 inch has been used for initial analysis.
If this assumption proves to be too conservative, the predicted dif ferential settlement is used instead.
I f
i 2.5.4-27a
BVPS-2 FSAR hj fi f
Slope stability 1.5 for all permanent loading conditions; 1.1 for SSE loading conditions and for construction slopes.
Hydrostatic uplift 1.1 for maximum water levels.
Sliding 1.5 for all permanent loading conditions; 1.1 for SSE loading conditions.
A discussion of loads and load combinations used in the design of Category I structures is provided in Sections 3.8.1.3 and 3.8.4.3.
2.5.4.12 Techniques to Improve Subsurface conditions A zone of loose granular material from approximately el 640 to 660 feet was discovered in the BVPS-2 area during the excavation for the containment foundation.
The extent of the loose zone was conservatively defined from exploratory borings as' a zone containing a significant number of samples having N values less than 10, as 1
determined by the Gibbs and Holtz (1957) relationship. A discussion of the criteria used to establish the limits of the densified zone is provided in Section 2.5.4.8.
Subsequent investigation revealed that the loose zone was. present under roughly the northern half of the containment and extended east and west beneath most of the Category I
-structures.
The loose zone was successfully densified using the pressure injected footing technique. The densification program and its evaluation are fully described in the Keport on soil Densification Program (DLC 1976).
Plots of N values obtained during 3
the verification program are presented on Figures 3-29, 3-30, and 3-31 of the report. These plots show that all samples of the loose sand and gravel zone have been densified to obtain N values greater 3
than 10.
Figure 3-30 shows five data points with N values that are 1
less than 10; however, these samples are not sand.
The removal of uncontrolled fill that was placed during the construction of SAPS and BVPS-1 is discussed in Section 2.5.4.5.
The removal of a lens of stiff silty clay found during the containment excavation is also discussed in Section 2.5.4.5.
The approximate limits of densification of the lower terrace sands and gravels beneath the BVPS-1 circulating water lines and river water lines (WR) and the BVPS-2 service water lines (SWS) are shown on Figure 2.5.4-16.
This densification program is described in responses ta USAEC questions 2.26 and 2.27 in the-BVPS-2 PSAR (DLC 1972e).
Initially, BVPS-1 had been designed with a once-through cooling system with an intake structure located near the present location of the BVPS-1 cooling tower. The Category I river water lines for BVPS-I had been located directly adjacent to the 108-inch circulating water lines leading to this intake structure.
Concern had been expressed that in the event of the liquefaction of soils along the Amendment 6 2.5.4-28 April 1983 i
~_,_.
BVPS-2 FSAR
%U hf~
circulating water lines, erosion resulting from their possible rupture could disturb the adjacent river water lines and it was decided to densify the sands and gravels beneath the circulating water lines using vibroflot.ation to preclude this problem.
After completion of the densification program, but before the installation of the circulating water lines, the decision was made to change from a once-through cooling system to closed-cycle cooling towers.
Due to space limitations on the site, it was necessary that the intake structure be relocated to its present location as shown on Figure 2.5.4-16.
The soil conditions underlying the service water and river water i
lines from the point where they cross the circulating water lines to the present location of the intake structure are similar to the previous location and are typical of the low level terrace.
The subsurface profile extending from the valve pit to the intake structure is provided on Figure 2.5.4-54.
Although the results of al liquefaction analysis of the soils north of the circulating water!
lines to the intake indicated an adequate factor of safaty againstI liquefaction (Appendix 2H, BVPS-1PSAR),itwasdecidedtodensifyj the sands and gravels beneath the river water and service water system lines also.
A typical section through the densified zone is l' shown on Figure 2.5.4-58.
l The granular soil to the south of the densified zone on thei intermediate terrace will not be subject to liquefaction (DLC 1976).!
If zones of granular material underlying the lower terrace outside of ;
the densified zone were liquefied, flow slides are improbable since slope toward the river appreciably butl the rock surface does not remains relatively flat at el 620 feet.
Although some surface subsidence of the soils outside of the densified zone could occur, major movements affecting the support of the service water and river water lines are not likely.
The densified area would be constrained against movement towards the river by the densified area adjacent to the intake structure itself.
The limits of densification of the lower terrace sands and gravels beneath the Category II circulating water lines and the Category I service water lines to the intake structure are shown on Figure 2.5.4-16.
As shown, the soil was densified to the top of rock using vibroflotation under two of the circulating water lines from just west of the service water lines eastward to near the cooling tower.
The soil underlying the service water lines to the intake structure was also densified. The subsurface profile extending from the valve pit to the intake structure is presented on Figure 2.5.4-54.
The locations of verification borings 537 through 562 are shown on Figure 2.5.4-13.
The results of the verification borings are presented on Figure 2.5.4-56.
The minimum allowable relative density for this area was 75 percent. Only two of 178 sand and gravel samples show relative densities less than 75 percent; Amendment 6 2.5.4-28a April 1984
Dju [ bb ff-d BVPS-2 FSAR therefore, the program was successful. The mean relative density indicated by the verification boring data was 97.7 percent and the a
mean-less-one-standard-deviation relative density was 91.4 percent.
The densification under the circulating water lines was done because the intake structure was originally planned for a different location, near the present BVPS-1 cooling tower, and the service water lines were to run parallel to the circulating water lines.
This work is described in the BVPS-2 PSAR response to USNRC Questions 2.26 and 2.27 addressed in Appendix 2A of the BVPS-2 FSAR.
There was a concern that the nondensified granular soils adjacent to the main intake structure, should they liquefy during cn SSE, could block the intake channel and/or clog the pumps. To prevent this from occurring, two areas approximately 75 feet by 90 feet on the east and the west side of the main intake structure were densified in 1974 by the L. B. Foster Company of Union, llew Jersey using the Terra Probe method.
The approximate limits of the densification program are ;
shown on Figure 2.5.4-16.
Amendment 6 2.5.4-28b April 1984
BVPS-2 FSAR C
yf h%
- I The Terra Probe consists of a vibratory pile driving hammer to which a 30-inch diameter open-ended tubular probe is attached. The unit is suspended from a crane and vibrated into the soil.
Densification occurs as the vibrating probe is withdrawn from the soil.
Forty-six verification borings were performed to evaluate the effectiveness of the densification program, the locations of which are shown on Figure 2.5.4-32.
The median relative density at each boring location was required to be not less than 75 percent in the sands and gravels as determined using the Gibbs and Holtz l
relationship.
In any one boring, not more than one sample point l
within the sands and gravels was allowed a relative density less than 1
70 percent and none were allowed to be less than 65 percent.
If these criteria were not met, the area around the failing boring was redensified.
l A test program was conducted to determine the optimum grid spacing for the Terra Probe.
Three borings, TH-1 through TH-3, were performed before the test densification and three borings, TH-4 through TH-6, were performed afterwards.
It was decided that a 5-foot grid spacing would be adequate to achieve the densification requirements.
Prior to beginning the production densification program, 12 borings
..were performed to allow a comparison of relative densities before and after densification.
(Figure 2.5.4-32).
A summary plot of relative densities before and after densification is given on Figure 2.5.4-43.
Relative density plots of each individual verification boring are provided in Appendix 2.5C.
Boring logs are provided in Appendix 2.5B.
Upon the completion of the initial series of borings, both of the areas were densified using the 5-foot grid spacing.
Prior to densification, the material between the sheetpile walls was excavated to expose the tie rods at approximately el 663 feet to facilitate the insertion of the Terra Probe.
After densification, backfill material was placed before performing the verification borings.
Verification borings performed subsequent to the initial densification revealed that the de.-ired densities were not being achieved in all cases.
A second test panel was conducted in which a single Terra Probe was inserted and withdrawn from the soil.
Three verification borings were performed, one in the center of the probe location and two at increasing distances from the probe (Borings 559T, 560T, 561T).
It was found that in this particular area, densification was occurring within the probe itself and for a distance of about 8 inches outside the probe.
Selected areas offshore were redensified using a 5-foot grid spacing which overlapped the original densification pattern.
The onshore areas were redensified using a
2.5-foot grid spacing.
Figure 2.5.4-32 shows the approximate areas in which each of the densification patterns were performed.
2.5.4-29
'3 BVPS-2 FSAR 4
v d@9 Eleven borings performed after the final densification program indicated that the densification requirements had been achieved. The D'
boring locations are given on Figure 2.5.4-32 and summaiy plots of relative density before and after densification are given on Figure 2.5.4-43.
The densification program required that the mean f}%
relative density at each boring location be not less than 75 percent
~4 for the sands and gravels as determined by the Gibbs and Holtz (1957) d{
relationships.
In any one boring, not more than one sample within the sands and gravels was allowed a relative density less than 70 Eg percent and none were allowed to be less than 65 percent.
It E q q The results of the after-densification borings are summarized on i b, Figure 2.5.4-43.
Only three of 93 sand and gravel samples have relative densities less than 65 percent, and of these, two are very m C $ close to the soil surface.
- Thus, it is concluded that adequate r
b d 00 densification of the sands and gravels was achieved with a mean
.I R *[ t relative density of 92.3 percent and a mean-less-one-standard-3 g g Q deviation relative density of 79.8 percent.
[
1
-t-2.5.4.13 Surface and Subsurface Instrumentation Insed "C" 0%e. 33.4 -30b)
The settlements of all BVPS-2 Category I structures are being g
monitored during con truction and will be monitored throughout the 4
life of the plant. f comprehensive program was establistied in mid-l
p977tomonitorthesettlementsduringconstruction and to aid in establishing the long-term, post-construction settlement monitoring; (program.g During construction, settlement markers are monitored monthly
)dhen the (individual}Ttructures at e fully loaded and their settlement -
profiles begin to level out, the period between readings will be increased.
Permanent bench marks er installed at various locations around the site to provide reliable survey reference points.
Several piezometers Get=e installed tofmonitor changes in ground-water elevation 6n orderh_to evaluate possible correlations between settlement data and changes in ground-water elevation.
In each g
5e structureTa_ series of) settlement markers 6ere or will beIinstalled M ~ (during construction 6 $liel) are /GlocatedJthat they can' be monitored clor% d.
tfirDUglicut the e v n 3Utu i. iv a uim w as well a [after ccustruction. The locations of the bench marks and piezometers are shown on Figure 2.5.4-14 and the locations of the settlement markers installed at present are shown on Figures 2.5.4-44 and 2.5.4-45.
The observed settlements to date (Figure 2.5.4-46) can be compared with the predicted total static settlements Q shown on Figure 2.5.4-20.
2.5.4.13.1 Bench !! arks Six permanent bench marks were installed at the locations shown on Figure 2.5.4-14.
A typical bench mark installation detail is shown on Figure 2.5.4-47.
It consists of a 2-inch diameter extra strong Amendment 8 2.5.4-30 February 1984
BVPS-2 FSAR YI O
steel pipe anchored into bedrock inside of a 3 1/2-inch diameter t
casing extending to the top of rock. The bench marks are identified by a brass monument inscribed with the bench mark number, elevation, coordinates, and date of initial survey.
The elevations of the bench marks were checked at three-month intervals for the first year after installation and once per year thereafter.
In addition, the elevations of bench marks in the 1
Amendment 8 2.5.4-30a February 1984 i
n.
' - ~ ' '
^^~
Insert "C" Differential settlements along buried, safety-related piping that extends i
from the structures out into the yard and differential settlements of piping that spans the shake spaces between the closely spaced main plant area structures are not monitored as part of the settlement monitoring progran.
Section 2.5.4.10.2 describes the calculation procedures used to estimate the differential settlements that are used for pipe stress analysis.
l 4
1 f
4 2.5.4-306 j
i I
,9--_t-9---.
, - _,,. -, ~.. _, - -
.,.,.,__w,_-,-.-
m-. _ - -. -. - -
-.n
..,. -. - ~ ~ ~ ~. _ - ~ _ -,,, _ - -. _ _, ~. _.. _ _. _ _ _ _. _
t BVPS-2 FSAR 0
qJ kJ f3p immediate vicinity of construction activities are monitored monthly I.
and any bench mark that is disturbed or is suspected ~
being of disturbed is resurveyed.
Bench marks are checked by running one or a series of leveling loops within the established bench marks.
If, by comparison with the elevation measured during the original survey, it has been determined that a bench mark has been disturbed, a new brass monument is installed ar.d the bench mark resurveyed.
All survey work performed in conjunction with checking and reestablishing bench marks is done using first order vertical control.
2.5.4.13.2 Piezometers Six stand pipe piezometers were installed at the locations shown on Figure 2.5.4-14.
Typical piezometer installation details are shown on Figure 2.5.4-27 and specific installation data are given in Appendix 2.5A.
Tip elevations range between el 646 and el 651 feet and all of the piezometers are located within the in situ sand and gravel.
Piezometer data and Ohio River elevation data are recorded weekly and
,'are included in Appendix 2.5A.
With the exception of one period during February 1979, the ground-water levels recorded in the piezometers show very good correlation with the Ohio River elevations.
During February 1979, the river rose to el 681 feet and the piezometer data indicate ar. apparent time lag.
- However, the piezometers were only read weekly during the period of high water and in the interim between readings the water level in the piezometers may have continued to rise, thereby reducing the apparent elevation difference between the ground-water levels and the Ohio River elevation.
2.5.4.13.3 Settlement Markers The locations of the currently installed settlement markers are shown on Figures 2.5.4-44 and 2.5.4-45.
Details of the several types of markers are shown on Figure 2.5.4-48.
Construction activity in certain structures requires that settlement markers be relocated periodically in order to provide continuing access to the markers.
In such structures, temporary markers have been installed instead of permanent markers. Temporary settlement markers have been installed on the reactor containment building, the safeguards area, the fuel and decontamination
- building, and the cooling tower.
When construction activity diminishes to the point that markers are no longer subject to periodic relocation, the temporary settlement markers are replaced with permanent ones.
I I
Amendment 8 2.5.4-31 September 1984
BVPS-2 FSAR 2.5.4.13.4 Data Processing Data processing is accomplished using a SWEC computerized data storage system entitled Settlement Monitoring System (IS-233).
The settlement marker elevations are input into the computer storage files and a computer printout providing the complete settlement record of each marker is produced. A specimen page of output is given on Figure 2.5.4-49.
For each settlement marker, ettlement versus ie lots have been prepared.usina arithmetic and foo time scales.) These plots are not included" herein but are provided in dhe report ordttlemen[
onitorina Proaram (DLC,1980 7 A summary of the observed settlements to date is provided on Figure 2.5.4-46.
The Ohio River elevation and piezometer data is included in Appendix 2.5A.
2.5.4.14 Construction Notes The removal of uncontrolled fill placed during the construction of SAPS and BVPS-1 is discur, sed in Section 2.5.4.5.
The removal of a lens of stiff silty clay found during the reactor containment excavation is also discucted in Section 2.5.4.5.
'A zone of loose granular material was discovered in the BVPS-2 area during the excavation for the reactor containment excavation.
It was densified using the pressure injected footing technique.
The densification program and its evaluation are fully described in the Report on Soil Densification Program, (DLC 1976).
2.5.4.15 References for Section 2.5.4
- Audibert, J. !!. E.
and Nyman, K.J.
1977.
Soil Restraint Against Horizontal Motion of Pipes. Journal of the Geotechnical Engineering Division. ASCE October, 1977.
- Bowles, J.
E.
1977.
Foundation Analysis and Design. McGraw-Hill Book Company, New York, N.Y.
- Bullen, K.
E.
1963.
An Introduction to the Theory of Seismology.
Cambridge University Press, Cambridge, England.
Christian, J. T. 1976.
Relative !!otion Between Two Points During an i
Journal of the Geotechnical Engineering Division, Vol.
102, No. GT11.
November, ASCE.
Dravo Corporation 1974.
Subsurface Investigation Routing of Sludge Transportation Pipes Around Beaver Valley Power Station, Little Blue Amendment 10 2.5.4 !!ay 1985 i
i
__.,_.,_,___..,_.-._..,--g_,_.
, _.. - _ - - _ _ -,. _ _ _ _,. _,,.,, _ _ _,,,,, -,,, -, _ _ _ _ ________.m._
_