ML20116G495

Suggested Spec of Issue Re Soils.Certificate of Svc Encl

ML20116G495
Person / Time
Site:	South Texas
Issue date:	04/26/1985
From:	Axelrad M HOUSTON LIGHTING & POWER CO., NEWMAN & HOLTZINGER
To:	Atomic Safety and Licensing Board Panel
Shared Package
ML20116G453	List: ML20116G447 ML20116G467 ML20116G495
References
OL, NUDOCS 8505010514
Download: ML20116G495 (18)

Text

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UNITED STATES OF AMERICA NUCLEAR REGULATORY COMMISSION

(

DOCMETED USNRC BEFORE THE ATOMIC SAFETY AND LICENSING BOARD 15 APR 30 60 51 In the Matter of

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cFFICE O SECTUMY

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li%"ElIM [;.5N -

HOUSTON LIGHTING & POWER

)

Docket Nos. 50-498'OL" COMPANY, ET AL.

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50-499 OL

)

'(South Texas Project, Units 1

)

and 2)

)

APPLICANTS' SUGGESTED SPECIFICATION OF ISSUE RELATING TO SOILS In the Board's March 29, 1985 Memorandu n and Order (Denying Proposed Contention on Soil Stability but Directing Hearing on Certain Soils Questions) (Order) it put the parties on notice that it regarded "the matter of the Applicants' current organization, procedures and activities in soils areas as likely warranting further exploration in the Phase II hearings."

(Order, p. 8.)

It tentatively identified aspects of the " soils and foundation area" in which it was interested.

(Id., pp. 9-10.)

It indicated that the degree of attention to be given to this topic " depends, in part, on the soils work (ifeany) remaining to be undertaken," and that this subject will be explored at the April 30, 1985 pre-hearing conference.

(Id., p. 10, n.5.)

The amount of Category I backfill that remains to be placed at the South Texas Project (STP) is very limited.

A total of 2,300,900 cubic yards was required for-Unit 1, Unit 2 and Balance C-

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. oof Plant.

Of that total, 1,978,300 cubic yards were placed by Brown & Root and 216,000 cubic yards have been placed by Ebasco as of! March 24,,1985.

Accordingly, as of that date only 106,600 cubic. yards remained to be placed, or less than 5% of the total.

The remaining backfill work is made up of numerous areas re-quiring only small amounts of backfill.

There is no single area where the remaining backfill work is likely to exceed 5000 cubic yards and.no Category I. backfill operations remain to be performed under any major structures of the powerblock.

Such remaining-work can be generally categorized as of a miscellaneous nature involving areas such as backfill operations around manholes and duct banks

-and local areas of the ECW pipe trench.

These facts.suggest'that limited: attention should be given at the forthcoming hearing to the Applicants' organization and procedures for the remaining backfill activities.

Perhaps the Board's principal interest-lies in the adequacy of the backfill placed by Ebasco in light of the two violations referred ~to in I&E Report 83-26 and the two findings (findings 23 and 24) in the programmatic audit submitted by HL&P on May 25, 1984, as alluded to at page 9 of the Order.

Accordingly, Applicants suggest that the issue to be heard in 7.

Phase II concerning the-soils and foundation area be specified as 9.

follows:.

"G.

Is there reasonable assurance that the backfill ~placed at STP by Ebasco is in con-formity with the construction permits and the provisions of Commission regulations in light of'the two violations in the area of ' soils-

r-m and foundation' discussed in I&E Rept. 83-26

-(dated Aprill20, 1984) and findings 23 and 24 in the programmatic. audit filed by HL&P on May 25, 1984 (ST-HL-AE-10 9 5 ) " ?

In suggesting this specific issue, we have noted that the Board pointed out that "the material before us does not reflect monitoring requirements (if any) employed to detect future ex-cessive differential settlement, but it raises certain questions concerning the adequacy of base line data (see, e.g., programmatic

-audit, at pp.-8-9, findings 23 and 24)."

(Order, p. 9.)

To the extent that the Board may have had in mind a concern as to the adequacy of the backfill, such concern is explicitly addressed in our suggested Issue G.

However, the placement of backfill has no relationship to the monitoring for differential settlement nor to the " adequacy of base line data" for such monitoring referred to in the Order.

This was the reason why information pertaining to such subjects was not found in the materials cited by the Board.

The "Evalua--

tion and Location Base Line Control" and the " Settlement Moni-toring Program" for STP are discussed in Sections 2.5.C.2 and

-2 5.C.4, respectively, of Appendix 2.5.C of the FSAR; the loca-tions of horizontal and vertical baseline and control monuments are shown on Figure 2.5.C-1, and permanent structural benchmark locations are shown on Figure 2.5.C-3.

Copies of each of these materials are enclosed for the Board's convenience.

Since the monitoring program and the adequacy of baseline data for such monitoring are not affected by the placement of backfill, they are not brought into question by the NRC and HL&P reports which the

' Board has reviewed and there appears to be no reason to take up such matters at the Phase II hearings.

Moreover, consideration of monitoring for differential settlement in the absence of any new information would be par-ticularly inappropriate since the subject of-criteria for dif-ferential settlement, and monitoring thereof, was raised and resolved to the Licensing Board's satisfaction at the construction permit hearing.

See LBP-75-46, 2 AEC 271 at 315 (1975); LBP 71, 2 AEC 894 at 907 (1975).

Accordingly, Applicants respectfully suggest that the Board adopt Issue G, as formulated above, as the specification of the issue in the " soils and foundation area" to be heard in Phase II of this proceeding.

Respectfully submitted,

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~

Jack R. Newman Maurice Axelrad Alvin H. Gutterman Steven P. Frantz Donald J. Silverman 1615 L Street, N.W.

Washington, D.C.

20036 Finis E. Cowan 3000 One Shell Plaza Houston, Texas 77002 Dated:

April 26, 1985 NEWMAN & HOLTZINGER, P.C.

ATTORNEYS FOR HOUSTON LIGHTING 1615 L Street, N.W.

& POWER COMPANY, Project Manager Washington,.D.C.

20036 of the South Texas Project acting herein on behalf of itself and BAKER & BOTTS the other Applicants, THE CITY 3000 One Shell Plaza OF SAN ANTONIO, TEXAS, acting by Houston, Texas 77002 and through the City Public Service Board of the City of San Antonio, CENTRAL POWER AND LIGHT COMPANY, and CITY OF AUSTIN, TEXAS

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STP FSAR is' C

APPENDIX 2.5.C

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GEOTECHNICAL MONITORING r

2.5.C.1 Introduction A comprehensive geotechnical instrumentation monitoring program has been established to measure the settlement of facility structures, to measure regional ground-surface subsidence, to measure lateral movement of excavation slopes (slope stability), and to monitor the performance of the construction dewatering systems. These monitoring programs were designed to provide basic data for verification of predicted plant foundation performance. Evaluation of the monitoring data pertaining to slope stability and dowatering enhances the safety of the project during construction by giving advance warning of any potentially adverse events. The geotechnical instrumentation monitoring pro-gram was implemented in conjunction with the foundstion verification program (see Section 2.5.4.5 and Appendix 2.5.A) and a geological mapping program (see Section 2.5.1 and Appendix 2.5.B) to provide a comp 2ete evaluation of the supporting stratification and the performance of the foundations of the facil-ity structures.

The settlement portion of the geotechnical instrumentation monitoring program consists of an array of borehole heave points, extensonetsrs, and structural bench marks together with piezometers and pore pressure cells for groundwater observations in the plant area. The regional ground surface subsidence moni-toring program consists of an array of shallow and deep aquifer open standpipe piezometers, a network of vertical and horizontal ground control bench marks.

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and a deep reference bench mark with continuous subsidence monitoring instru-mentation. These monitoring programs and resulting data accumulation and evaluations are discussed in detail in this appendix. The data and evalua-tions for lateral movement of excavation slopes and dewatering are addressed in Sections 2.5.4.5 and 2.5.4.6, respectively. The geotechnical instruments used for lateral movement and dewatering system monitoring and their methods of installation are, however, described in this appendix.

2 2.5.C.2 Elevation and Location Base Line Control Base line control for vertical and horizontal datum were established at the STP site during 1973 for the various site explorations and property surveys.

The vertical datum was established by a first-order-level loop from a National Geodetic Survey (NGS) monument near Wadsworth Texas. This monument had ear-lier (1973) been resurveyed (reestablished) by the NGS by their own first-order-level loop from a monument established in bedrock near Austin, Texas. Therefore, the vertical control used at the STP for explorations, construction, and monitoring is 1973 datum.

The horizontal base line control was established at the STP site during 1973 by a first-order traverse between various NGS horizontal control monuments.

This traverse was subsequently used to establish horizontal positions for site explorations and the grid system for plant construction. The STP horizontal control network utilizes the Texas State Plane Coordinate System (Southern Zone), which is a Lambert conformal projection system.

2.5.C-1 Amendment 44

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4 STP FSAR t

The locations of the horizontal and vertical base line monuments for the plant area are provided on Figure 2.5.C-1 together with the regional subsidence g

monuments. Figure 2.5.C-1 identifies several of the vertical control monu-

,r ments as primary reference bench marks as well as a secondary bench mark used for geotechnical monitoring. The primary bench marks were used to establish vertical datum, as subsequently discussed for each monitoring system. The cecondary bench marks were used as vertical reference points for interim peri-cds and periodically, (biweekly) verified or adjusted by a second-order-level loop to a primary bench mark (datum). Temporary bench marks (not shown on Figure 2.5.C-1) were used on a daily basis as vertical points of reference in the plant area and were verified or adjusted by a second-order-level loop to a cecondary bench mark on a daily basis.

2.5.C.3 Data Accumulation Processing, and Storage The measurement data from the settlement, subsidence, and construction dewa-taring monitoring systems are reduced and stored, and can be retrieved in tabular or graphical format by the computer data processing system, GEMIS.

K4 This processing system has the capabilities to store all base line informa-tion, reduce field data to actual elevations (ft mean sea level [MSL]) of the -

cbservation points, calculate differential movement between the field measure,

ments and base line data, print field data in tabular format together with reference point elevations and differential movements, and generate time-history plots of observation points. The time-history plots can be cuperimposed or stacked allowing concurrent observations from several instru-ments or different observation points within an instrument to be depicted.

In March 1982 GEMIS was superseded by CEMP-Geotechnical Engineering Monitoring Program (Ref. 2.5.C-2).

GEMP has the same capabilities, performs the same functions and produces the same output as described for the GEMIS program.

35 All project data previously stored in GEMIS has been transcribed into GEMP ctorage. Monitoring data acquired after March 1982 is compatible with previ-cusly filed information.

2.5.C.4 Settlement Monitoring Program The settlement analysis performed during the design phase is addressed in Section 2.5.4.10.3.

Geotechnical parameters and criteria described in that section are those applied in the preconstruction analysis. An extensive set-tienent monitoring system has been implemented during construction as described in this appendix. The details of the settlement monitoring system cnd the evaluation of the data are described in the following sections.

l35 2.5.C.4.1 Settlement Monitorina System Description. The settlement monitoring program is capable of monitoring heave and settlement of individual coil layers during construction as well as the actual heave or settlement of plant structures. This was accomplished by the installation of 19 borehole heave points (BHPs) in the plant area, 4 BHPs for the Essential Cooling Water piping,14 Sonde extensometers (Sondex), and in excess of 100 structural bench l44 Structure, 12 BHPs and 4 settlement plates for the essential cooling water marks. The locations of Sondex and BHP instruments are shown on Figure 2.5.C-2, and the locations of permanent structural bench marks are shown on Figure 2.5.C-3.

The piesometer and pore pressure cell data used to monitor the effectiveness of the dewatering system (see Section 2.5.4.6) were also 2.5.C-2 Amendment 44

STP FSAR used to evaluate the effects of dewatering on soil deformation during con-struction. In addition, a record of events and foundation loads which affect i

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the stress conditions in the STP plant area was maintained to document the actual construction stress history of the foundation soils.

To isolate the heave and settlement deformations resulting from plant con-struction from the deformations (regional subsidence) resulting from regional groundwater withdrawals, a primary reference bench mark (denoted "VP" on Fig-ure 2.5.C-1) was established in near-surface soils outside the range of influ-ence (heave / settlement effects) of the plant construction. The establishment of this bench mark as datum from the settlement monitoring program and the maintenance of this datum unchanged (although the bench mark was subject to regional subsidence effects) allowed effective isolation of the two phenomena, 2.5.C.4.1.1 Subsoil Instrumentation: Sonde extensometers (Sondex) were t

installed to depths of 230 ft and 300 ft below the ground surface. The Sondex consists of horizontally corrugated plastic tubing with gaging rings fixed at selected increments (typically 5-ft spacing) throughout the depth of the installation. The flexible nature of the Sondex tubing, which permits the gaging rings to move vertically as the soil expands and/or compresses during construction, allowed an accurate determination of the movement of individual soil layers in the depth range of the Sondex.

Borehole heave points were installed below the final excavation bottom. The BHPs are deep bench mark monuments that permit periodic monitoring of hea,ve and/or settlement of the soil at the level of the BHP anchor. The BHPs.

allowed measurement of the total accumulated heave and/or settlement of the

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soil below the anchor elevation.

At several locations the BHP and Sondex instruments were installed adjacent to each other, as shown on Figure 2.5.C-2.

This redundancy permitted a check of the observations by direct comparison of the observed deformations at corre-l sponding elevations. The designs of the Sondex and BHP instruments are shown

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on Figure 2.5.C-4.

2.5.C.4.1.2 Structural Bench Marks:

Structural bench marks have been l

installed on plant structures as plant foundation and substructure construc-l tion proceeded to allow monitoring of heave and/or settlement both during j

construction and plant operation. The locations of the permanent structural bench marks are shown on Figure 2.5.C-3.

During initial foundation construc-tion, temporary structural bench marks were established in proximity to the permanent installations so that there could be continuity of measurements until the permanent structural bench marks were installed.

2.5.C.4.2 Instrument and Installation Description.

l 2.5.C.4.2.1 Sonde Extensometer:

The Sonde extensometer (Sondex) con-i sists of 3-in. (nominal) inside diameter (ID) corrugated plastic tubing with j

metal wire gaging rings affixed at approximately 5-ft intervals as shown on Figure 2.5.C-4, detail A.

A 2-1/2-in. (nominal) diameter polyvinyl chloride i

(PVC) pipe mandrel was places inside the corrugated tubing to facilitate

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installation, to provide added support for the tubing, and to guide the sensor probe. The corrugated plastic tubing and mandrel were installed in

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8-3/4-in.-diameter, rotary-drilled boreholes stabilized by 6-in.-diameter

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steel casing during the Sondex installation.

2.5.C-3 Amendment 44

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STP FSAR To facilitate installation, the Sondex corrugated plastic tubing and PVC pipe mandrel were divided into segments and spliced together when lowered into the

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borehole. Drainholes were cut in the bottom segment, and it was weighted to overcome the hydrostatic pressure of the drilling fluid in the borehole. The annular space between the corrugated Sondex tubing and the soil of the bore-hole wall was backfilled with pea gravel as the steel casing was extracted.

The pea gravel functioned as a medium to transmit vertical strains from the soil to the corrugated plastic Sondex tubing. The upper portions of the Sondex were dismantled in short segments as the excavation exposed them and 5

the mandrels were subsequently spliced together in short segments as the backfill was placed. The Sondex was extended through the concrete foundations to allow continued monitoring during plant construction until the piezometric levels in the ground (and hence through the Sondex) increased because of dewatering system shutdown to the point that further measurements were 2

impractical because of upward flow of water.

The Sonde extensometers are monitored by lowering an electronic probe with a W

steel surveyor's tape through the PVC pipe mandrel; the probe produces a sig-

+

'nel by inductance as it passes the moral wire gaging rings. The probe is connected by cable to a sensitive readout device. When the readout device g

indicates that the probe is adjacent to a metal wire gaging ring, the location of a 1-ft marker on the surveyor's tape is recorded relative to the scale mounted on the tripod. The elevation of this scale is established by survey-ing to an accuracy of 0.01 ft before and after each set of measurements is obtained. The actual depth readings to the gaging rings are likewise obtained-to an accuracy of 0.01 ft.

The readings are obtained from the bottom of the instrument moving up. The recorded data include the surveyed elevation of the scale and the depth measurements to each gaging ring.

2.5.C.4.2.2 Borehole Heave Points: The BHP consists of a lower, 2-in.-diameter steel pipe anchor unit and an upper, detachable steel riser pipe of the same diameter. A 1-1/2-in.-ID inner pipe sleeve is welded to the anchor and extends into the riser pipe, but is free to move vertically rela-tive to the riser pipe. Details of this instrument are shown on Figure 2.5.C-4.

The BHPs were installed in an 8-3/4-in.-diameter, rotary-drilled hole pene-trating 10 ft below the excavation bottom. The hole was stabilised with drilling mud which was flushed out before the anchor was placed. The anchor j

was grouted in place and the riser pipe lifted about 1 ft 3 in. above the top of the anchor to permit unencumbered movement of the anchor. A packer was placed around the riser pipe about 11 ft above the bottom of the anchor to assure adequate space for free movement, and the remainder of the hole was backfilled with pea gravel.

The equipment used to obtain measurements of BHPs consists of a mechanical The torpedo with spring-loaded pawls connected to a steel measuring tape.

4 torpedo is lowered with the pawls extended, and the pawls catch the lower edge of the 1-1/2-in. pipe sleeve in the anchor unit, which is the observation 4'

point (see Figure 2.5.C-4 Detail B). The distance from the top of the riser pipe to the observation point is then recorded. The elevation of the top of 5

j the riser pipe is determined by surveying each tima a measurement is obtained.

Amendment 44 2.5.C-4 j

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s STP FSAR 2.5.C.4.2.3 Structural Bench Marks: The structural bench marks consist of 2-1/2-in.-diameter brass markers with a convex head anchored in the con-(

crete by a 2-in.-long ribbed shaft. The elevations of structural bench marks are established by conventional survey techniques.

2.5.C.4.3 Fractuency of Observation. The heave / settlement monitoring instrumentation is observed on a weekly, bimonthly, or monthly basis, depend-ing upon the rate of the imposed construction loads, the instrument type, and the accessibility of the instrument. The minimum observation frequencies are given in Table 2.5.C-1.

In general, during the heave cycle (resulting from plant area excavation) the Sondex and BHP instrumentation was read on a weekly basis. Following installation of the structural bench marks on the various foundations and during the commencement of the recompression cycle, the i

instruments continued to be read on a weekly basis assuring overlap of the l

subsoil data with the structural bench mark data. Thereafter, the frequency of observation of the subsoil instruments and their counterpart (adjacent) i structural bench marks varies from weekly to bimonthly readings; while, the k

frequency of observation of structural bench marks that were not immediately

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adjacent to subsoil instrumentation is varied from bimonthly to monthly read-ings.

2.5.C.4.4 Interpretation of Field Data. The heave / settlement monitoring data are subject to evaluation by geotechnical engineering personnel. The processed data are also reviewed before the information is used for subsequent studies and analysis.

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For the preliminary construction plans settlement studies (1979 & 1981) the j{,

behavior of the instrument data (time-histories) was studied with respect to:

Reliability, i.e., the field measurements were obtained with the required l 35 l.

accuracy.

2.

Validity, i.e., the measurements as observed represent ground movement i

at the observation point. The validity study is focused sequentially on: l 35 i

l a.

Reasonableness, i.e. the observation being in general agreements l 35 i

with the expectations.

b.

Responsiveness, i.e., the observed movements correlate positively with known stress changes and that the movements are in the expected direction.

c.

Representativeness, i.e., assessment of the mass of soil represented by the instrument and the correlation of the observed movement to 35 this defined mass.

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2.5.C.4.4.1 Construction Phase Settlement Studies: The heave / settlement behavior to be expected during the plant construction period was analyzed 35 during the design phase (1974-1975). A preliminary construction phase re-analysis was started during 1977 using the came model and parameters as used during the design studies; however, the actual schedule and load applica-j tion events were used as input for the stress history. Reasonable comparisons i f between predictions and actual performance were generally obtained near the i \\

foundation elevations.

l 35 A"*"d**"t 4' 2.5.C-5

STP FSAR The preliminary construction phase re-analysis also included using a deeperThe ctratigraphic column and a more efficient and versatile computer program.

preliminary (1979) studies included two of the three regimes of heave / settle-

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ment process, that is, heave and recompression of heave. The third regime.

net settlement, was being approached when the preliminary study was completed.

In 1983, an additional settlement evaluation was made which included projec-tions of the movement curves. This evaluation included the use of the revised 35 construction load schedule, and the use of the field instrument data obtained through April 1983. The study also considered the effect of the main cooling reservoir (MCR) embankment load and water load (Ref. 2.5.C-1).

The study utilized the information from the previous (1979) analysis, an interim (1981) etudy, and the trend line plots of instrumentation data from construction day

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1500 (approximately 19 October 1979) to construction day 2800 (approximately 11 May 1983).

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The projections of future settlement were made using the previous analyses and instrument data. This was confirmed with an analysis using a consolidated model based on a compressibility concept similar to a compression / tension spring analogy.

The results of the construction phase settlement analysis described herein are

• further addressed in Section 2.5.C.4.5 below. The settlement projection curves for the behavior of the structures are shown on Figure 2.5.C-9 2.5.C-9A 2.5.C-10, and 2.5.C-10A superimposed on the actual observations.

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35 2.5.C.4.5 Predicted and Actual Movement.

2.5.C.4.5.1 Unit 1 Area: The actual movements for the Reactor Contain-ment, Fuel Handling, Mechanical-Electrical Auxiliaries, and Diesel-Generator 26 Buildings are shown on Figures 2.5.C-9 and 2.5.C-9A.

These curves have been taken directly from Sondex, BHP, and Structural Bench Mark observations at l43 points near the foundation elevations for the buildings, as noted on the fig-

'O1N The projected movement curves, based on the settlement analysis as 26 ure.

described in Section 2.5.C.4.4.1 above, have been superimposed on the observed q movement curves for each building. These projected movement curves are based 241 on the settlement analysis for actual construction loads and instrument data The projected movement curves show an agreement with the actu- [O1N 44 to April 1983.

si observed heave, recompression, and settlement.

35 The projected maximum differential settlement between structural bench mark l

(SBM) locations, see Figure 2.5.C-3, is shown on Table 2.5.C-4.

The projected tilt within the various structures is shown on Table 2.5.C-5.

The observed The differential movement between buildings is shown on Figure 2.5.C-11.

5 differential movement profile within buildings (tilt) is shown on Figures F

2.5.C-13A and 2.5.C-135.

The effect of the embankment load and water load of the essential cooling pond was considered in the Design Phase (1974-1975) analysis and the recent (1983)

The essential cooling pond has little effect on the settlement projections.

settlement of Unit 1 because there is very little load and subsequent subsur-j face stress field change. The pond is but a rearrangement of' load due to the shallow excavation and low dikes.

4 2.5.C-6 Amendment 44

3 STP FSAR The effects of the MCR embankment and water load have been considered (Ref.

2.5.C-1).

The effect of the embankment, which has been in place some time, is accounted for in the field instrument data and subsequently the current (1983) settlement projections which used the instrument data. The effect of the MCR water load (Ref. 2.5.C-3) on the structures will be eas11. It is on the order 35 of 0.005 feet (approximately 1/16 inch) and was not taken into direct account because it is such a small value.

Very little differential settlement has been observed between the Unit 1 buildings. Also, very little anticipated differential settlement is projected for the Unit 1 structures (Table 2.5.C-4).

The anticipated tilt after day i

3400 (Approximately end of 1984) for Unit 1 (Table 2.5.C-5) is projected to be 39 small.

2.5.C.4.5.2 Unit 2 Area: The actual movements for the Reactor Contain-ment Fuel Handling, Mechanical-Electrical Auxiliaries, and Diesel-Generator 26 Buildings are shown on Figures 2.5.C-10 and 2.5.C-10A.

These curves have been Q

3.

obtained directly from Sondex, BHP, and Structural Bench Mark observations at 241 t

points near the foundation elevations for the buildings as noted on the fig-

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ure.

1 The projected movement curves are based on the settlement analysis as de-scribed in Section 2.5.C.4.4.1, above, have been superimposed on the observed 35 movement curves for each building. The projected movement curves are based on the settlement analysis for actual construction loads and instrument data.to l

May 1983 and the anticipated Unit 2 construction loads and schedule. The.

l44 projected movement curves show an agreement with the actual observed heave.

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recompression and settlement.

The projected maximum differential settlement between locations (see Figure 1

2.5.C-3) are shown on Table 2.5.C-6.

The projected tilt within the various structures is shown on Table 2.5.C-7.

The observed differential movement between buildings is shown on Figure 2.5.C-12.

The differential movement profile within buildings (tilt) is shown on Figure 2.5.C-14.

The effect of the essential cooling pond embankment load an water load was not 35 i

considered for the Unit 2 settlement evaluation and projection. It was not l

considered because it is quite distant from Unit 2 and has no effect on the i

stress field beneath Unit 2.

The effect of MCR is the same as previously discussed for Unit 1.

A small amount of differential settlement has been observed between the Unit 2 buildings. Generally only a small amount of future differential settleeent is anticipated. The anticipated tilt for Unit 2. Table 2.5.C-7, is generally j

small.

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2.5.C.4.6 conclusions.

2.5.C.4.6.1 Behavior of Foundation Soils and Structures: The current geotechnical instrumentation data show that the foundations soils in the plant area did heave and recompress in good agreement with the projections obtained from the preliminary construction phase analysis. The projections have been 35

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updated (1983) to reflect the actual load history, the projected loading, and l

l 2.5.C-7 Amendment 44

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STP FSAR l

schedule to completion, and are shown on Figures 2.5.C-9 and 2.5.C-9A for Unit 35 1 and Figures 2.5.C-10 and 2.5.C-10A for Unit 2.

9 The differential movements between Unit 1 structures measured as of aid 1984 are shown on Figures 2.5.C-11 and 2.5.C-11A.

The recorded differential move-ments vary from negligible between the Isolation Valve Cubicle (IVC) and the Reactor Containment Building (RCB) to about 1 in. between the IVC and the 44 Turbine-Generator Building (TGB).

The differential movements between the Unit 2 structures measured as of aid 1984 are shown on Figures 2.5.C-12 and 2.5.C-12A.

These differential move-ments vary f-em negligible between the Mechanical Electric Auxiliary Building (MEAB) and the RCB to 0.4 in. between the MEAB and the FHB.

The measured differential movements between structures for Unit 1 and Unit 2 35 to date are within the design criteria defined in Section 2.5.4.11.

The measured differential movements within the structures of Unit 1, as of aid 44 1984 are shown on Figures 2.5.C-13A and 2.5.C-13B.

These figures indicate that there was very little change in the differential movements since February.

35 1982. The maximum differential movements were 0.2 in. in the RCB, 0.6 in. in the FHB (north-south section). 0.7 in. in the MEAR (east-west section) and 0.1.l44 in. in the DGB.

35 The measured differential movements within the structures of Unit 2 as of aid 1984 are shown on Figures 2.5.C-14 and 2.5.C-14A.

The measured anximum dif-44 forential movements were 0.1 in. in the RCB, 0.6 in. in the FHB (north-south section) 0.6 in the MEAB (east-west section) and 0.2 in. in the DGB.

The measured differential movements and tilt within structures for Unit 1 and 35 2 are within the design criteria defined in Section 2.5.4.11.

2.5.C.4.6.2 Predictions of Differential Movements Durina Plant Operation: The design criteria for differential settlement affecting piping systems are defined in Section 2.5.4.11 and are applicable after the actual pipe connections between the buildings have been made. It is estimated that l43 no pipe connections are to be made prior to the end of 1984.

l39 The projected tilt and differential settlement for Unit 1, af ter c%struction l35 day 3400 (end of 1984) are reported in Tables 2.5.C-4 and 2.5.C-5.

The values ate acceptably small.

The projected tilt aci differential settlement for Unit 2, after construction 39 day 3400, are reported in Tables 2.5.C-6 and 2.5.C-7.

The projected tilt and differential settlement for Unit 2 after day 3400 will be acceptably small.

1 2.5.C.5 Regional Subsidence Monitoring Program zThG,51_Jtezional Subsidence Monitorina System Description. The regional subsidence h *=! oro ran is capable of monitoring both vertical and horizontal ground surface movemen TP site. This is accomplished by the installation of a deep reference bench mark, a..._: -ar ace monuments for measurement of vertical ground surface movement, and 9 near-sur a = x x ments for measurement of horizontal ground surface movement (see Figure 2.5.C-8 Amendment 44

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UNITED STATES OF AMERICA NUCLEAR REGULATORY COMMISSION BEFORE THE ATOMIC SAFETY AND LICENSING g g,

USNRC In the Matter of

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15 APR 30 A10:51 HOUSTON LIGHTING & POWER

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Docket Nos. 50-498 OL GFFICE OF ?Ebi (South Texas Project, Units 1 )

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CERTIFICATE OF SERVICE I hereby certify that a copy of Applicants' letter enclosing (1) " Applicants' Reply to CCANP Response to ASLB Memorandum and Order of February 26, 1985 and Applicants' Suggested Specification of Quadrex Findings To Be Litigated," and (2) " Applicants' Sug-gested Specification of Issue Relating to Soils," has been served on the following individuals and entities either by deposit in the United States mail, first class, postage prepaid, on April 26, 1985, or by air courier as indicated by "*" on April 26, 1985.

C* Charles Bechhoef er, Esq.

• Brian Berwick, Esq.

Chairman, Administrative Judge Assistant Attorney General Atomic Safety and Licensing for the State of Texas Board Panel Environmental Protection U.

S. Nuclear Regulatory Commission Division Washington, D.C.

20555 411 W.

13th Street

• Dr. James C. Lamb, III Administrative Judge Kim Eastman, Co-coordinator 313 Woodhaven Road (Saturday Barbara A. Miller Chapel Hill, NC 27514 Delivery)

Pat Coy Citizens Concerned About

• Ernest E. Hill Nuclear Power Administrative Judge 5;06 Casa Oro Hill Associates San Antonio, TX 78233 210 Montego Drive (Saturday delivery)

Danville, California 94526

• • Lanny Alan Sinkin 3022 Porter St.

N.W.,

1. 304 Mrs. Peggy Buchorn Washington, D.C.

20008 Executive Director Citizens for Equitable

• Ray Goldstein, Esq.

Utilities, Inc.

Gray, Allison & Decker Route 1, Box 1684 100 Vaughn Building Brazoria, TX 77422 807 Brazos (Monday Austin, Texas 78701-2553 Delivery)

Additional copies to be hand delivered on April 29, 1985 where designated by "**"

h

- **Oreste Russ Pirfo, Esq.

Robert G. Perlis, Esq.

Office of the Executive Legal Director U.S. Nuclear Regulatory Commission Washington, D.C.

20555 Atomic Safety and Licensing Board U.S. Nuclear Regulatory Commission Washington, D.C.

20555 Atomic Safety and Licensing Appeal Board U.S. Nuclear Regulatory Commission Washington, D.C.

20555 Docketing and Service Section office of the Secretary U.S. Nuclear Regulatory Commission Washington, D.C.

20555 Ify (AM t j

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