ML20136B728
| ML20136B728 | |
| Person / Time | |
|---|---|
| Site: | 05000000, Vogtle |
| Issue date: | 10/04/1984 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML082840446 | List:
|
| References | |
| FOIA-84-663 NUDOCS 8601020885 | |
| Download: ML20136B728 (44) | |
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o ENCLOSURE GEORGIA POWER COMPANY V0GTLE ELECTRIC GENERATING PLANT UNITS 1 AND 2 DOCKET NOS. 50-424 AND 50-425 STRUCTURAL AND GE0 TECHNICAL ENGINEERING BRANCH SAFETY EVALUATION REPORT
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E s Gi ~e. e a i s Q TABLE OF CONTENTS P,,, age.
I 2.5.4 Stability of Subsurface Materials and Foundations.............
2.5.4.1 Site Conditions......................................
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2.5.4.1.1 General...................................
2.5.4.1.2 Site Foundation Description...............
2-2.5.4.1.3 Site Investigations.......................
2b 2.5.4.2 Engineering Properties of Foundation Materials.......
'I 2.5.4.3 Engineering Properties of Backfill Materials.........
Ek 2.5.4.4 Foundation Stability.................................
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2.5.4.4.1 Construction Notes...............'.........
13 2.5.4.4.2 Bearing Capacity..........................
12L 2.5.4.4.3 Settlement................................
1 55 2.5.4.4.4 Lateral Pressures.........................
kG2 L ~I 2.5.4.4.5 Liquefaction Potential....................
2.5.4.4.6 Dynamic' Loading'...........................
\\Eb LEb 2.5.4.5 Instrumentation and Monitoring.......................
2.5.4.6 Remaining Issues.....................................
L9) 2.5.4.7 Conclusions.......'...................................
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o Vogtle Electric Generating Plant, Units 1 and 2 Docket Numbers:
50-424/425
Subject:
Draft Safety Evaluation Report - Geotechnical Engineering Prepared by:
Joseph D. Kane, SGEB, DE NRR The following sections summarize the staff's geotechnical engineering review of the Vogtle Electric Generating Plant, Units 1 and 2, as presented in the Final Safety Analysis Reports (FSAR) through Amendment No. 9, dated August 1984 and the applicant's response to staff questions, nos. '241.1 through 241.24.
The stability of subsurface materials and foundations (FSAR Section 2.5.4) has been evaluated in accordance with the applicable criteria outlined in 10 CFR 50, 10 CFR 100, Appendix A of 10 CFR 100, Regulatory Guide (R.G.) 1.70, " Standard Format and Content of Safety Analysis Reports for Nuclear Power Plants" (Revi-sion 3), R.G._1.132, " Site Investigations for Foundations of Nuclear Power fe s, Plants," R.G.1.138, " Laboratory Investigations of Soils for Engineering Anal-ysis and Design of Nuclear Power Plants," and IfrRESE55Co., " Standard Review Plan (SRP), NUREG-0800, July 1981.
The site conditions which exist at the Vogtle site do not involve stability of slopes nor embankment and dams, and therefore, FSAR Sections 2.5.5 and 2.5.6 are not addressed in this Draft Safety Evaluation Report (SER).
2.5.4 Stability of Subsurface Materials and Foundations 2.5.4.1 Site Conditions i
't 2.5.4.1.1 General I
i The Vogtle Electric Generating Plant (VEGP) is located on the southwest side of the Savannah River in Burke County, Georgia, approximately 26 miles south-west of Augusta, Georgia.
The site topography is one of rolling hills with original ground surface elevations in the immediate plant area (excluding the 7.,
river intake canal and structure) generally ranging from.e1. 225 ft. above 09/21/84 1
VCGTLE SER
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Final plant grade is at el. 219.5 ft. and this level required the removal of-the upper natural soils.
TheSavanghRiverat its closest point is approximately 3000 feet northeast from the main plant area and.has a normal water elevation of 80 ft.
The maximum water level in the Savannah; River has been estimated at el. 165 ft. under assumed Probable Maxi-num Flood (PMF) conditions that include allowance for wave runup.
As described in Section 2.4 of this SER, groundwater movement has been observed in an upper water table aquifer system and a confined aquifer system that is located below approximately el. 70 ft. The foundation designs of seismic Category I struc-tures have been based on a maximum groundwater elevation of 165 ft. and this
-maximum level would be located in the upper water table aquifer system.
2.5.4.1.2 Site Foundation Description The subsurface conditions as revealed by explorations and foundatio em:ava-tions in the plant site area may be divided into three, principal strata.
The top stratum consists of sands (SP), silty sands (SM); and clayey sands (SC)
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7.g and in the FSAR this top layer is identified as the upper sand stratum.
The upper sand stratum is about 85 ft. -in thickness below plant grade and has a
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bottom elevation at approximately el. 135 ft.
A shelly limestone (Utley Lime-stone), which subsurface explorations showed to be subjected to extensive leaching and to solution cavities, is located at the base of the upper sand stratum Sd ranged up to 12 feet in thickness.
The stratum below tne Utley Limestone is the major foundation supporting' layer and is identified as the clay marl be'aring stratum.
The clay marl stratum is approximately 65 feet in thickness in the main plant area and ranges in elevation between 135 ft. and 70 ft.
The clay marl stratum is a gray to greenish gray, calcareous silty l
clay with shell fragments and fnterbedded with limestone and sand lenses.
I Drilling recoveries show the marl to be pre. dominantly a hard to very hard, weakly cemented material with some zones of softer marl.
Seismic explorations indicated a velocity interface about 15 feet below the top of the clay marl stratum which is a reflection of weathering in the upper 15 feet of the marl A thick,. dense, coarse to fine sand zone with minor interbedding of zone.
silty clay and clayey silt layers is located beneath the clay marl stratum.
I, n.
This loweh sand stratum is' estimated to be in excess of 750 feet in thickness g
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and recorded blows counts per foot of penetration in the Standard Penetration Test (SPT) are generally in excess of 100 blows.
A decision to excavate the upper natural soils and extend this excavati'on into the clay earl stratum was made by the Applicant in order to avoid foundation difficulties with the shelly limestone layer and to eliminate any potential for liquefaction.in the upper sand stratum.
Liquefaction had been indicated to be a possibility in the upper sands,when evaluated, allowing for a seismic event equivalent to the Safe Shutdown Earthquake (SSE). This extensive foundation excavation operation required the removal of approximately 5 mil-lion cubic yards of soil to el. 130 ft. and measured approximately 1000 ft.
along each side at the bottom of the excavation which was roughly square in shape.
A deeper excavation to el. 108.5 ft. in the clay marl stratun was made over a rectangular area measuring 120 ft. by 440 ft. to accommodate the base-mat for the deeper portion of the auxiliary butiding.
Description of the geologic mapping, dewatering activities, rebound monitoring, surface clean-up and protection measures, foundation inspection and approval procedures are provided in Appendix 28 of the FSAR.
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The foundations of seismic Category I structures that are evaluated in this draft SER include the reactor containment buildings, nuclear service cooling water (NSCW) towers and pumphouses, auxiliary building, fuel handling build-ing, control-building, diesel generator buildings, diesel fuel oil storage tanks and buildings, condensate storage tanks, auxiliary feedwater pumphouses, refueling water storage tanks, reactor make-up water storage tanks and Category I piping, conduits and tunnels.
Reinforced concrete mat foundations were used for Category I structures with the exception of wall footings for certain tanks, and box culverts for piping and tunnels.
FSAR Figure 241.2-1 provides a plan view of the main plant layout and identifies the outline of seismic Category I structures.
Having excavated the natural soils to the clay marl stratum has the result of placing the foundations of most seismic Category I structures on compacted backfill.
Only the more deeply founded auxiliary building, NSCW towers and instrumentation cavity of the containment building are founded on the clay i
mar 1.
All other foundations of the power block structures are supported on J
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Category I backfill and have foundation elevations ranging from el.158 ft.
f (reactor building) to el. 218 ft. (reactor make-up water storage tanks).
Category 1 backfill was selectively excavated from nearby borrow sources and consisted of medium to fine sands (SP) and sands with some silt (SP-SM).
Although permitted by PSAR and FSAR documentation to contain up to 25 percent by weight passing the No. 200 sieve, the percent of fines actually contained in the Category 1 backfill that was placed and compacted was limited in the l
field to_about 12 percent.
All Category 1 backfill in the power block area was to be compacted to an average of 97 percent of the maximum dry density
. determined by American Society of Testing Materials (ASTM) D1557, with no tests below 93 percent and not more than 10 percent of the tests between 95 and 93 percent.
Based on the results of test fill studies, the Applicant indicated his intent was to control the placement moisture content of the Category 1 backfill to within i 2 percent of the optimum moisture content determined by ASTM D1557 (FSAR Section 2.5.4.5.2.7).
The staff's evaluation on the adequacy of the compacted backfill is subsequenty aiscussed in this SER '
' gg in Section 2.5.4.3.
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2.5.4.1.3 Site Investigations Field investigations at the site were initially started in January 1971 and l.
were continued during construction with 38 borings being drilled from the i
bottom of the foundation excavation on the top of the clay marl bearing stra-tum in 1977 in the power block area.
The field investigations have included drilling, geophysical seismic surveys, groundwater studies and geologic map-ping of foundation excavations.
A total of 474 holes have been drilled of which 111 holes were completed subsequent to the PSAR investigations.
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' Table 28-1 of the FSARsprovides a ifst of borings with summary information for foundation investigations completed for the PSAR.
l The site investigations were completed to define the various subsurface materials and stratification, to obtain soil samples for laboratory testing and the establishment of engineering properties, to identify sources of suitable g
borrow, to permit measurement of shear and compression wave velocities, to determine in situ foundation material permeabilities and groundwater movement 09/21/84 4
V0GTLE SER
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and for geologic mapping and inspection (e.g. for faulting, cavities, soft j
zones) of foundation excavations for approval prior to concrete placement.
The investigations completed at the VEGP site did not extend to firm bedrock which is estimated to be approximately 750 feet below the bottom of the clay earl stratum.
On the basis-of its review of the information presented in the FSAR, the staff concludes that the site investigations completed by the Applicant are accept-able and adequate to identify the important subsurface features and foundation conditions, with the exception of the "CS" series holes drilled in 1977 from on top of the clay marl stratum.
The staff in question 241.3 of its review of the FSAR attempted to understand the reasons for the poor core recovery in the clay marl stratum that was indicated in 9 of the 36 borings which were drilled in 1977.
Portions of the Applicant response to question 241.3 which Y provided in Amend. 6 (5/84) are j
not acceptable to the staff and this concern remains an open review item.
The basis for this staff position includes the following:
a.
The Applicant's response to question 241.3 indicates that the 1977 marl sampling program was not an exploration program and was not designed to obtain 100 percent core recovery but rather was' intended to obtain selected samples
- of the clay earl for laboratory testing. The staff has great difficulty in understanding this response.
In our opinion the borings of the "CS" series, I
some'of which were drilled within the foundation limits of the NSCW towers, auxiliary building, containment buildings, control building and fuel handling building, were important to assessing the foundation competency of the clay marl stratum and should have been drilled in accordance with good engineering-practice and the guidelines of R.G. 1.132 " Site Investigations for Foundations of Nuclear Power Plants." Good engineering practice would require a full and
. complete description 'of the materials encountered for the entire depth and an l
explanation on the boring logs for the zero percent recoveries in order to properly assess this condition on the adequacy of foundation design and future building peformance.
Supplementary explorations specifically intended to determine the features of the zones of the poor core recovery would normally be completed.
The Applicant's response that this program was intended to 09/21/84 5
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obtain selected representative samples of the marl stratum needs to be further explained, if it implies only good intact rock core specimens were to be laboratory tested.
b.
The staff is unclear as to the significance in the Applicant's response of indicating-that six of the nine borings with zero recovery are located outside of the limits of seismic CategoryI structures.
Certainly the borings are close enough to safety related structures to reasonably permit extrapolation of the subsurface information to these structures.
The staff recognizes that the Applicant has made similar extrapolation of subsurface data in its assess-ment of the clay marl stratum where it has relied on information from caisson excavations and outcrop locations that are located at considerably greater distances from seismic Category I structures.
The staff also recognizes that widely spaced borings may not, in many instances, allow detection of adverse anomalies, discontinuities or lenses or pockets of unsuitable material and that there is an important need to respond to these indications, such as zero percent recovery when it does occur, particularly at locations where leaching
. and solution cavities have been observed.
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The staff agrees with the Applicant that the preponderance of subsurface o
information indicates that no,pcavities exist below the top of the clay marl stratum. The staff is less certain that zones of softer material do not exist in the clay marl.
The softer zones could be factor by having engineering properties significantly lower than values used in foundation design.
The f
staff attempted to gain confidence in the foundation adequacy of the marl layer, in spite of the difficulties with the "CS" borings, by reviewing the recorded settlements of structures founded on or close to the top of, clay marl stratum. As discussed in Section 2.5.4.4.3 of this SER, the settlement records providedfortheauxiliarybuildingandreactorcontainmentbuilding(areindi-cating total settlements larger than anticipated for the years of plant opera-
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tion with approximately 87 percent of the total static loading already placed.
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Settlement records for the f 'aCW towers have not yet been provided.
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Engineering Properties of Foundation Materials 2.5.4.2
.c Description of the types of foundation materials has been provided in Section 2.5.4.1.2.
The engineering properties of these materials were estab-lished by laboratory testing and field testing and are summarized in the following FSAR tables and figures:
Topic Table No.
Range of Engineering Static Properties for Site 2.5.4-1 (Natural) Soils ngineering Static Properties Adopted in 2.5.4-2 Design - Site (Natural) Soils Engineering Dynamic Properties Adopted in 214.12-1 and Design - Site Soils Figures 3.7.B.1-9 and 3.7.B.1-10 Figures 2.7.8.2-6 and be. spces bebee., dgyehpcs 3.7.s.2-7 h
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? ".=. 2 k. - T On the basis of its review of the information provided in the FSAR, the staff concludes that the engineering properties determined for foundation materials
.are acceptable and meet the applicable portions of the Commission's regulations, SRP, and R.G.1.138, " Laboratory Investigations of Soils for Engineering Analysis and Design of Nuclear Power Plants." The staff also notes, however, the extremely variable properties of undrained shear strength and soil modulus of elasticity for the clay marl that have been established in laboratory testing.
It is the extreme variability which gives the staff concern for the appropriateness of the adopted design values for undrained shear strength and soil. modulus of elasticity (FSAR Table 2.5.4-2) and for the strain-dependent dynamic soil shear moduli and damping curves (Figures 3.7.B.2-6 and 3.7.B.1-9) for the clay marl stratum. ' The staff's concerns are further discussed in this SER'in Sections 2.5.4.1.3, 2.5.4.4.3, and 2.5.4.4.6.
2.5.4.3 Engineering Properties of Backfill Materials A description of the materials placed and compacted as Category 1 backfill soils
- has been provided in Section 2.5.4.1.2.
In localized areas that restricted compaction because of space limitations, lean concrete was used in place of back-fill. The engineering properties of Category 1 backfill were established by laboratory testing and are summarized in the follcwing FSAR tables and figures:
Topic Table No.
Engineering Static Properties Adopted in Design 2.5.4-8 241-Engineering Dynamic Properties Adopted in Design Figures GE R.12-1, 3.7.B.1-8, 3.7.B.2-5 8
09/26/84 255 V0GTLE SER ORAFT SEC 2 INPUT
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Test fills on Category I backfill were constructed to determine the appropriate lift thickness, number of passes and to evaluate the performance of different compactors in order to achieve the required maximum densities.
The FSAR, as originally submitted, did not provide information on the actual results from field control testing on compacted Category 1 backfill.
In response to staff' question 241.4 and to discussions at a March 1984 site visit, the Applicant provided compaction control records for backfill material placed during the first 6 months of 1983.
Following their review and evalu-ation of.'the field records,;the staff expressed the following difficultes with the submitted informaton.
1.
'Many of'the laboratory determined maximum dry densities (ASTM 1557) appeared unusually low in the staff's opinion.
These low densities, when used to establish the percent compactica, would result in the reporting of values in excess of 100 percent.
p 2.
The field procedures used by the Applicant' to demonstrate that fill V
placement moisture contents met FSAR commitments also gave a problem to the staff.
The field procedures followed would consist of running a fill moisture content immediately before compaction to verify that the fill moisture was within the specified range of an average optimum moisture content that had been predetermined on stockpiled fill material.
The staff's problem resulted from the moisture testing of the fill before compaction and using this result to decide on moisture acceptability i
rather than the more normal practice of testing the fill after compac-f tion.
The normal practice of testing after compaction has the advantage I
of verifying the uniform mixing of water throughout the entire lift thickness, which is required by the compaction control specification.
Also it is the compacted condition of the fill (density and molding water content) which will govern the resulting engineering properties.
The Applicant's procedure of using an average optimum moisture content also presented a problem to the staff because it differs from normal procedures where the optimum moisture is directly established in the lab on the same type of material that is field tested for density.
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V0GTLE SER ORAFT SEC 2 INPUT
e a In order to address the staff's concern with compaction of Category 1 backfill, a confirmatory laboratory testing program was agreed upon with the Applicant
.and testing was initiated in June 1984.
The major objectives of the confirma-tory testing program consisted of the following:
1.-
Evaluate the acceptability of the quality control test procedures and test l
results for the compacted Category 1 backfill by determining whether FSAR commitments (Section 2.5.4.5.2) had been met in obtaining the required maximum dry densities. The check on acceptability was to be made by requiring both the field lab and an independent testing laboratory to perform control tests (gradation, moisture-density relationships, rela-tive density and permeability) on the same Category 1 backfill material.
Identical samples of fill material were selected from existing stockpiles.
2.
Reexamine the FSAR commitments on compaction control (maximum dry density I
and placement'siioisture contents) after evaluation of the results from the confirmatory testing program and determine if modifications of FSAR commit-
,Ih ments are warranted for the future control of Category 1 backfill that
' remains to be placed.
.The laboratory results of the confirmatory testing program were provided to the NRC in an August 10, 1984 submittal.
The Applicant needs to evaluate the results and submit a report to the NRC which responds to the program objectives.
Prelim-inary observations of the staff based on the results provided in the August 10, 1984 submittal indicate the following:
1.
A comparison of the maximum dry densities determined by the field lab and the independent testing firm indicates that the independent lab i
l results show higher value of maximum densities in all of the twelve tests performed using ASTM D1557.
The increase in densitites ranged from i
0.8 pounds per cubic foot up to 3.5 pounds per cubic foot.
[Themaximum l
difference in dry density from the loosest state to the densest state
.for the medium to finksand (SP) isabout 20 pounds per cubic foot.1f The differences in results between the testing labs for optimum moisture content l
detorminations were more widely scattered with differences ranging from I
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.J NS 7.6 percent moisture below optimum to 2.5 percent above for the tests on the same type of material.
2.
The test results also indicate that the backfill soils which have a small amount of fines (less than 6 percent passing the No. 200 sieve) attained their highest densities when tested in the relative density test (ASTM D4253) in six out of the seven tests performed.
The increase in maximum dry densities between modified Proctor (ASTM D 557) by the field lab and b.
relative density (ASTM 04253) testing range,from 2.4 pounds per cubic foot up to'4.5 pounds per cubic foot.
Recognition of these results would encourage a modification to current control procedures that requires the running of both the relative density test and the modified Proctor test in order to establish the maximum dry densities and percent compaction for this type backfill which has the small amount of fines.
The opportunity for the staff.to observe a portion of the actual testing by the independent lab has helped the staff to underst nd why higher densities are not more consistently obtained in the ASTM D15573 During this laboratory test a large part of the heavy compaction effort that is specified is actually
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lost during compaction, because of the large shear displacements which repeatedly occur in the test sample mold under the impact of the hammer weight.
These displacements and resulting loss in compactive effort appear to be greatest for soils being compacted at moistures on the wet side of optimum moisture content.
The staff believes the large displacements and resulting loss in l
compactive effort are a major reason for the differences in test results between the field lab which was indicated to use a mechanical tamper, and the independent testing lab, which manually compacted the test specimens.
Under manual compaction conditions there is a natural tendency to locate the next hammer blow where the displacements are occurring whereas, in mechanical tamping, a set pattern and sequence in compaction effort is followed.
The differences in results between the testing labs therefore, are more the result of the particular soil behavior under the specified compactor and allowable I
test. procedures of ASTM D1557, rather than being caused by errors or unaccep-(
table test procedures between the labs. The staff also believes the densitites obtained in the relative density tests are higher because the displacements do M
09/26/84 4t=4-V0GTLE SER DRAFT SEC 2 INPUT
.,.. m not occur and that the relative density test is better suited for VEGP backfill materials with less_than 6 percent fines.
The staff anticpates in the Applicant's future report which addresses the objectives of the confirmatory test program, that the higher maximum dry dwnsities obtained, for the three types of backfill materials tested, will be used to establish the percent compaction for all Category 1 backfill compacted to date.
Preliminary observations, when using the higher densities for the field records from the first six months of 1983, indicate that FSAR require-ments have essentially been met but at lower percent compaction values than originally reported.
2.5.4.4 Foundation Stability With the exception of the NSCW towers, the instrumentation cavity of the containment building and the auxiliary building, all seismic Category 1 struc-tures are founded on compacted Category 1 backfill.
The Applicant's response (Q
to staff question ami. 241.17 indicates that little or no settlement data are presently available for the auxiliary feedwater pumphouses, diesel generatork buildings, diesel fuel oil storage pumphouses and Category I tanks since these structures are either in the initial stages of construction or construction has not begun.
Also in response to question 241.17, tha Applicant indicates that settlement records for the NSCW towers and Category 1 tunnels are to be submitted to the NRC., Until.this construction is completed and described and the settlement data are provided to the NRC for evaluation, the staff would not be in a position to complete its final SER on foundation stability.
.The Applicant's response to staff question 241.1 indicates that the radwaste transfer building.and radwaste transfer tunnel, although not seismic Category I structures, could potentially adversely affect seismic Category I structures.
Based on the guidance in R.G. 1.29, the foundation design and construction of these structures would also then be required to meet the equivalent of seismic Category I requirements.
The foundation design and construction information for t.hese structure should therefore be provided for staff review.
The Appli-cant is also requested'to provide the reasons why the radwaste solicification d
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building, which has been founded on drilled caissons (refer to staff question 241.20), would not fall'into this same category.
i 2.5.4.4.1 Construction Notes During the years of plant construction several conditions were exposed or developed which are factors.that could affect long-term foundation stability.
These events included detection and foundation treatment of the solution cavities in the Utley Limestone above the clay marl stratum and the erosion of the already placed Category 1 backfill in November 1979 as a result of the heavy rainfall and surface runoff which entered the foundation excavation area.
Several cavities of varying size were exposed on the slopes of the foundation excavation where the slopes intersected the limestone shell bed.
The largest cavity was located on the northwest corner of the power block area and measured 10 ft by 10 ft at the opening and extended approximately 30 ft back into the
, /OS slope where it narrowed to a small size.
Other small cavities were encountered
- e at varying intervals all along the north side of the power block foundation i
excavation.
The cavities were cleaned of loose debris and then backfilled with crushed rock.
In the larger cavity the crushed rock was forced into the opening for at least a 25 ft length beyond th? opening by a ram attached to the blade of a bulldozer.
Filling of the cavities was performed to provide a buttress on the. foundation excavation slope against which structural backfill could be placed and compacted.
The areas affected by the soil erosion problem in November 1979 included zones 1) between the Control Building Electrical Shafts, Units 1 and 2 and the Turbine Building, 2) between Units 1 and 2 Containment Buildings and the Electrical Tunnels, 3) along the perimeter of Unit 1 Containment' Building and
- 4) beneath the mud slab of Unit 2 Tendon Gallery.- A detailed description of the areas affected and the remedial measures completed has been provided by the Applicant in the August 15, 1980 report, " Final Report on Dewatering and Repair of Erosion in Category 1 Backfill in Power Block Area." The limits of the areas disturbed by erosion were determined by inspection, field explora-j tions and testing using proving ring and dynamic core penetrometers and sand 1
09/26/84 1!4 V0GTLE SER ORAFT SEC 2 INPUT
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cone density tests.
The remedial measures completed between January and August of 1980 included reshaping of foundation excavation slopes and protec-tion with gunite, improvement in surface water controls, installation of additional dewatering measures and piezameters to insure that the water table level was maintained at sufficient depths in the Category 1 backfill to allow remov'al of mud slabs and disturbed soils and their replacement to be performed in the dry,and the pumping of grout into voids in the backfill in space restricted areas.
The Staff concludes that the Applicant's investigations and remedial measures are acceptable, but also recognizes that the success of these actions in addressing the erosion problem and filling of the cavities can best be judged by continued visual inspections of the structures performance and l'ong-term settlement behavior.
The staff requests that the location of all obsrved cavitiesbeidentifiedonappropriateFSARfiguresanddescribgdinorderto better understand their overall extent.
Thisrequestedinforg,couldpoten-tially prove useful when reviewing and evaluating future settlement records.
,a.
2.5.4.4.2 Bearing Capacity The Applicant's responses to staff questions nest.241.5 and 241.15 indicate that the results of bearing capacity analysis under static and dynamic loading will be submitted to the NRC by December 1, 1984.
The staff will complete its safety evaluation on the acceptability of the resulting margins of safety against bearing-capacity-type failure following review of the anticipated December 1984 submittal.
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2.5.4.4.3 Settlement The Applicant has responded to staff questions 241.17 and 241.18 by providing a portion of the settlement records for seismic Category 1 structures. The settle-ment records that remain to be submitted are identified in SER Section 2.5.4.4 The settlement records which were provided in reponse to question 241.17 are in a form that makes review and evaluation unnecessarily difficult.
These usm.9 submitted settlement records need to be improved by t,- {5a consistent interval of time for both settlement versus time and application of loading versus time information.
Both types of information should be plotted at the same time scale in order to permit a reasonable evaluation of settlement behavior under structure loading. The staff considers these provements -iw r' ry' ; th
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se essential
_,, hi. i; au_ before deciding on long-term settlement monderiq requirements for the Technical Specifications.
The Applicant's reply to staff question 241.18 is not responsive and is not acceptable for the following reasons:
C.nbg % conegved, 1.
dhere is no discussion or comparison of total and differential settlements allowed for in design with actual settlement records at specific struc-ture locations.
The Applicant's statement, that because all major seismic Category 1 structures are separated from each other by seismic gaps they are therefore unaffected by differential settlements, fails to recognize that excessive settlements can cause unacceptable structural cracking and high stresses and unacceptable tipping of the structure.
The staff's review of the limited settlement records that have been provided to date indicates that values of total settlement larger than the upper predicted
-values have been recorded for certain settlement markers (Nos. 128, 133, 134, 234, 235, 323, 324, 325) at the auxiliary building and Unit 1
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containment building.
These larger settlements have been recorded with 15 09/26/84
- d:h V0GTLE SER SEC 2 INPUT
approximately 87 percent of the total static load applied in comparison to the predicted values which were estimated for the 40 ar plant life.
The discussion requested in staff question 241.18 -is askEEg that the specific maximum recorded settlements be identified for each structure 2-
'dd'+4aa
--- /he recorded and be compar d to design estimates.
settlementDig"nificantandgpotentialadverseimpacty/h o future struc-ture performance (e.g.gracking, high stresses)4. -Art ments being observe D result of the clay marl stratum being less competent thanorginallyanticipgtedor:
M g possibly related to the soil erosionproblem).4ae.foundationdesignmodificationharranted).The engineering basis for the response to the above considerations should be clearly described in the Applicant's response.
2.
The Applicant's response to question 243.18 dees providesgeneral informa-tionondifferentialsettlementswhicharetypQallyaddressedinthe design of seismic Category 1 piping,but the response needs to be completed by providing specific VEGP information (locations, sectional views where appropriate) where total and differential settlements have been recorded q
and the significance of these settlements on the piping system's capability to safely withstand themgebeu dsscussef 2.5.4.4.4 Lateral Pressures The walls of seismic Category I structures below plant grade el. 219.5 feet were designed for static loading to resist at-rest lateral earth pressures using the equivalent fluid pressure concept.
The adopted design pressure diagrams are presented in response to question 241.21 and are discussed in FSAR Section 2.5.4.10.5.
An at-rest lateral earth pressure coefficient of 0.7 was used in design for the backfill materials.
A water level at el. 165 ft was conservatively used to establish the hydrostatic pressure contribution to lateral pressures.
For dynamic loading conditions, the Seed simplified version of the Mononobe-Okabe method was used for active earth pressures.
Dynamic passive pressures were calculated using a method Kapila that is based on the Mononobe-Okabe 4
09/26/84 V0GTLE SER SEC 2 INPUT
y..
method.
A peak horizontal ground surface acceleration of 0.20 g was used for SSE condition to estimate inertial forces.
With the exception of the approach for dynamic passive pressures, the staff concludes that the methods used to estimate later.a1 earth pressures are conser-vative and acceptable and are in accordance with current state-of-the-art engineering practice.
The staff needs to complete its. evaluation on the method used to establish dynamic passive pressures.
2.5.4.4.5 Liquefaction Potential The Applicant's decision to remove all the upper sand stratum materials and excavate the pr.,wer block area to the top of the clay marl stratum has the significant advantage of eliminating the potential for liquefaction that was indicated for the upper sand material.
The staff is in agreement with the Applicant that neither the clay marl stratum nor the deeper, dense lower sand stratum is susceptible to liquefaction under SSE conditons assuming a peak
{3 horizontal ground surface acceleration of 0.20 g.
To demonstrate that an acceptable margin of safety against liquefaction is available for structures and piping founded in the Category 1 backfill, the Applicant conducted cyclic shear strength tests on a representative range of backfill materials which were compacted to 97 percent of maximum dry density determined by ASTM 01557.
The lowest factors of safety against liquefaction type failure were on the order of 1.9 to 2.0 using the Seed-Idriss (1971) simplified method and the cyclic test results.
The staff concurs with the Applicant's findings that an acceptable margin of safety against liquefaction potential does exist for Category 1 backfill trat is compacted to 97 percent of maxium dry density.
The staff plans to reexam'ne this. conclusion on liquefaction potential following resolution of the concern discussed in SER Section 2.5.4.3 on compaction control procedures.
4 09/26/84 V0GTLE SER SEC 2 INPUT l
2.5.4.4.6 Dynamic Loading In staff questions 241.11 and 241.12 the Applicant was requested to provide the soil properties (shear modulus and damping values) for the soil springs used in the finite-element and lumped parameter dynamic studies and to compare these properties with the results from field geophysical surveys and lab cyclic triaxial testing completed for VEGP.
We have reviewed the Appli-cant's responses and have concluded the following:
1.
The strain-dependent soil damping curves for the compacted sand backfill (FSAR Figure 3.7.B.1-8) and the lower sand stratum (FSAR Figure 3.7.B.1-10) are reasonable best estimates and are acceptable to the staff.
The staff does not understand the basis for the change made by the Applicant for the damping curve (FSAR Figure 3.7.B.1-9) for the clay marl stratum between the time of FSAR docketing and Amendment 6 (5/84).
The staff requires that the basis for this change be provided and include a compar-ison that permits evaluation of the effects on structure behavior (e.g., reponse spectra) when both soil damping curves are used in design.
^
2.
The staff finds the strain-dependent shear moduli curves (FSAR Figures 3.7.B.2-5 through 3.7.B.2-7) to be reasonable best estimates and acceptable.
The staff requires, however, that the results of the study which varied the soil shear moduli values (Discussed in FSAR Section 3.7.8.2.4.1) by a factor of i 1.5 be provided and discussed and that the results permit a comparison of the resulting response spectra with final design spectra for the range of shear moduli values considered.
2.5.4.5 Instrumentation and Monitoring Because of the primary importance of the groundwater regime in the solution process and the resulting potential for ground subsidence, the staff will require adequate monitoring of both groundwater levels and settlement during the life of the VEGP project.
-T..; e....:;: :f/heobservationwellswhichwillbeactiveasindicatedinthe Applicant's response to question 241.10 need to be supplemented with additional Fe>
09/26/84 1==t-V0GTLE SER SEC 2 INPUT
- p., _. -
wells closer to the main plant complex and be located in both the upper water tabla aquifer and in the clay marl stratum at representative depths.
The staff requires that the Applicant provide a plan which locates the requested additional wells and the pertinent information on well installation and moni-re vash4 toring that is
_--t:J in question 241.10.
We ask clarification of the Applicant's response to question 241.19 as to whether it is intended that all settlement markers shown on FSAR Figure 241.19-1 are to be monitored for the entire life of the VEGP.
The staff feels it is initially important to resolve the issues identified in SER Section 2.5.4.4.3, to particularly,havp,uy a better understanding of the significance of the settle-ments which have already occurred.
Following resolution of the concerns express g ng eg i g g 4 4.3, g e staff feels it would be in a better posi-tion to, % long-term s b ement monitoring
,"'-^-^ +.
2.5.4.6 Remaining Issues
- ,m The remaining operating license safety review items which have been identified and discussed in the preceding SER sections are listed in Table 2.1.
Table 2.1 Remaining safety review items Review item SER Sections 1.
Foundation competency of clay marl 2.5.4.1.3, 2.5.4.2, stratum 2.5.4.4.3 2.
Verification of FSAR commitments on compaction of Category 1 backfill 2.5.4.3 3.
Submittal and evaluation of settlement records 2.5.4.4, 2.5.4.4.3 4.
Foundation design and construction information on radwaste buildings and tunnels 2.5.4.4 5
Locations and description of observed cavities 2.5.4.4.1 6.
Bearing capacity stability 2.5.4.4.2 7.
,Long-term groundwater and settlement monitoring requirements 2.5.4.4.3, 2.5.4.5 8.
Acceptability of variations in soil dynamic properties 2.5.4.4.6 0
09/26/84 W
V0GTLE SER SEC 2 INPUT
2.5.4.7 Conclusions On the basis of the staff's review of the information provided by the Applicant in the FSAR, the staff has concluded that the following features of foundation stability are acceptable, except as impacted by items in Table 2.1.
1.
Site Investigations 2.
Engineering static properties of foundation materials 3.
Foundation preparation measures including treatment of cavities 4.
Methods for estimating lateral earth pressures 5.
Margin of safety against ifquefaction potential 6.
Engineering dynamic soil properties Final overall conclusion on plant foundation stability requires resolution of the remaining issues identified in Table 2.1.
(.'~'
Co 09/26/84 E=&
V0GTLE SER SEC 2 INPUT
STRUCTURAL ENGINEERING 3.3 Wind and Tornado Loadings 3.3.1 Wind Design Criteria A11' Category I structures exposed to wind forces were designed to withstand the effects of the design wind. The design wind specified has a velocity of 110 mph at-30 ft. above grade based on a recurrence interval of 100 years.
The procedures that were used to transform the wind velocity into pressure loadings on structures and the associated vertical distribution of wind pres-sures and gust factors are in accordance with " Building Code Requirements for Minimum Design Loads in Buildings and Other Structures," ANSI Standard A 58.1 and BC-TOP-3A.
l The staff concludes that the plant design is acceptable and meets the require-ments of General Design Criterion 2.
This conclusion is based on the following:
The applicant has met the requirements of GDC 2 with respect to capability of the structures to withstand design wind loadings so that the design reflects 1.
appropriate consideration for the most severe wind recorded for the site with an appropriate margin; 2.
appropriate combinations of the effects of normal and accident conditions with the effects of natural phenomena; and 3.
the importance of the safety function to be performed.
The applicant has met these requirements by using ANSI A58.1 and BC-TOP-3A, which the staff has reviewed and found acceptable, to transform the wind
'09/26/84 3-1 V0GTLE SER INPUT - SEC. 3
y 5
9 velocity into an effective pressure on structures and for selecting pressure coefficients corresponding to the structural geometry and physical configuration.
Pending review and acceptance of the design report to be submitted in November, 1984, and the outcome of the design audit scheduled in December, the following conclusion will apply:
i The applicant has designed the plant structures with sufficient margin to pre-vent structural damage during the most severe wind loadings that have been determined appropriate for the site so that the requirements of item I above are met'.
In addition, the design of seismic Category 1 structures, as required by item 2 above, has included in an acceptable manner load combinations which occurksaresultofthemostseverewindloadandloadsresultingfromnormal and accident conditions.
The procedures used to determine the loadings on structures induced by the design wind specified for the plant are acceptable because these procedures i
n
- have'oeen'used in the design of conventional structures and been proven to provide a conservative basis which together with other engineering design.
considerations, assures that the structures will withstand such environmental forces. The use of these procedures provides reasonable assurance that in the event of design basis winds, the structural integrity of the plant structures that have to be designed for the design wind will not be impaired and, in consequence, safety-related systems and components located within these struc-tures are adequately protected and will perform their intended safety functions if needed. Thus, requirement of item 3 above is satisfied.
3.3.2 Tornado Design Criteria All Category I structures exposed to tornado forces and needed for the safe shutdown of the plant were designed to resist a tornado of 290 mph tangential wind velocity at a radius of 150 feet and a 70 mph translational wind velocity.
The simultaneous atmospheric pressure drop was assumed to be 3 psi at rate of 2 psi per second.
Tornado missiles are also considered in the design as dis-cussed in'Section 3.5 of this report.
7.
09/26/84 3-2 V0GTLE SER INPUT - SEC. 3
e The procedures that were used to transform the tornado wind velocity into pressure loadings are similar to those used for the design wind loadings as discussed in Section 3.3.1 of this report.
The tornado missile effects were determined using procedures to be discussed in Section 3.5 of this report.
The total effect of the design tornado on Category I structures is determined by appropriate combinations of the individual effects of the tornado wind pressure, pressure drop and tornado associated missiles.
Structures are arranged on the plant site and protected in such a manner that collapse of structures not designed for the tornado will not affect other safety-related structures.
Pending a satisfactory review of the design report to be submitted in November, 1984 and the outcome of the design audit scheduled in December,1984, the following conclusion will apply:
s.The staff concludes that the plant design is acceptable and meets the require-ments of General Design Criterion 2.
This conclusion is based on the following:
The applicant has met the requirements of GDC 2 with respect to the structural capability to withstand design tornado wind loading and tornado missiles so that the design reflects 1.
appropriate consideration for the most severe tornado recorded for the site with an appropriate margin; 4
2.
appropriate combinations of the effects of normal and accident conditions with the effects of the. natural phenomena; and 3.
the importance of the safety function to be performed.
The applicant has met these requirements by using ANSI A58.1 and BC-TOP-3A to transform the wind velocity generated by the tornado into an effective pressure on structures and for selecting pressure coefficients corresponding to the
~
structural geometry and physical configuration.
09/26/84 3-3 V0GTLE SER INPUT - SEC. 3
The applicant has designed the plant structures with sufficient margin to pre-vent structural damage during the most severe tornado loadings that have been determined appropriate for the site so that the requirements of item 1 above are met.
In addition, the design of seismic Category 1 structures, as required by item 2 above, has included in an acceptable manner, load combinations which occur as a result of the most severe tornado wind load and the loads resulting from normal and accident conditions.
The procedures used to determine the loadings on structures induced by the design basis tornado specified for the plant are acceptable because these pro-cedures have been used in the design of conventional structures and been proven to provide a conservative basis which together with other engineering design considerations assures that the structures will withstand such environ-mental forces.
The use of these procedures provides reasonable assurance that in the event of design basis tornado, the structural integrity of the plant structures that have to be designed for the tornadoes will not be impaired and, in consequence, safety-related systems and components located within these structures are ade-quately protected and will perform their intended safety functions if neede1.
Thus the requirements of item 3 above are satisfied.
3.4.2 Water Level (Flood) Design Procedures The design flood level resulting from the most unfavorable condition or combi-nation of conditions that produce the maximum water level at the site is dis-cussed in Section 2.4.
The hydrostatic effect of the flood was considered in the design of all Category I structures exposed to the water head.
The procedures utilized to determine the loadings on seismic Category I struc-tures induced by the design flood or highest groundwater level specified for the plant are acceptable because the procedures provide a conservative basis for engineering design to ensure that the structures will withstand such
~
environmental forces.
09/26/84 3-4 VCGTLE SER INPUT - SEC. 3
~
- The staff concludes that the applicant has met the requirements of GDC 2 with respect to the structural capability to withstand the effects of the flood or highest groundwater level so that the design reflects 1.
appropriate consideration for the most severe flood recorded for the site with an appropriate margin;
. 2.
appropriate combinations of the effects of normal and accident conditions with the effects of the natural phoonmena; and l
3.
the importance of the safety function to be performed.
i l
The applicant has designed the plant structures with sufficient margin to pre-i vent structural damage during the most severe flood or groundwater and the l
associated dynamic effects that have been determined appropriate for the site so that the requirements of item 1 above are met.
In addition, the design of i-seismic Category 1 structures, as required by item 2 above, has included in an I[,
acceptable manner load combinations which occur as a result of the most severe flood or groundwater-related load and the loads resulting from normal and accident conditions.
The procedures utilized to determine the loadings on seismic Category I struc-t l
tures induced by the design flood or highest groundwater level specified for
{
the plant are acceptable because these procedures have been used in the design of conventional structures and been proven to provide a conservative basis which together with other engineering design considerations ensures that the structures will withstand such environmental forces.
The use of these procedures provides reasonable assurance that in the event of I
floods or high groundwater, the structural integrity of the plant seismic Category I structures will not be impaired and, in consequence, seismic Cate-4 l
gory I. systems and components located within these structures will be adequately l.
protected and may be expected to perform necessary safety functions, as required, thus' satisfying requirement of item 3 above.
!,e i
I 09/26/84 3-5 V0GTLE SER INPUT - SEC. 3
A 3.5.3 Barrier Design Procedures The plant Category I structures, systems, and components are shielded from, or designed for, various postulated missiles.
Missiles considered in the design of structures include tornado generated missiles and various containment internal missiles, such as those associated with a loss-of-coolant accident.
Information has been provided indicating procedures that were used in the design of the structures, shields and barriers to resist the effect of missiles.
The analysis of structures, shields and barriers to determine the effects of missile impact is accomplished in two steps.
In the first step, the local effect is considered and the potential damage that could be done by the missile in the immediate vicinity of impacts is investigated.
This is accomplished by estimating the depth of penetration of the missile into the impacted structure.
In the second step of the analysis, the overall structural response of the target when impacted by a missile is determined by methods of impactive analy-sis, i.e., the force-time solution, the response chart solution, and the energy balance solution.
i Pending review and acceptance of the design report to be submitted in November, 1984, and the outcome of the design audit seneduled in December, the following conclusion will apply:
The staff concludes that the barrier design is acceptable and meets the require-ments of GCC 2 and 4 with respect to the capabilities of the structures, shields, and barriers to provide sufficient protection to equipment that must withstand the effects of natural phenomena (tornado missiles) and environmental effects including the effects of missiles, pipe whipping, and discharging I
fluids.
This conclusion is' based on the following.
The procedures utilized to determine the effects and loadings on seismic Category I structures and missile shields and barriers induced by design basis missiles selected for the plant are acceptable because these procedures provide
~
a conservative basis for engineering design to ensure that the structures or barriers are adequately resistant to and will withstand the effects of such 7
forces.
09/26/84 3-6 V0GTLE SER INPUT - SEC. 3
o,.
Tha use of these procedures provides reasonable assurance that in the event of design basis missiles striking seismic Category I structures or other missile shields and barriers, tne structural integrity of the structures, shields and barriers will not be impaired or degraded to an extent that will result in a loss of required protection.
Seismic Category I systems and components pro-tected by these structures are, therefore, adequately protected against the effects of missiles and will perform their intended safety function, if needed.
Conformance with these procedures is an acceptable basis for satisfying in part the recommendations of Standard Review Plan 3.5.3 and the requirements of General Design Criteria 2 and 4.
3.7.1 Seismic Input In the design of Vogtle Electric Generating Plant seismic Category I structures, systems, and componeats, an operating basis earthquake (OBE) of 0.12 g and a safe shutdown earthquake (SSE) of 0.20 g were specified.
The input seismic design response spectra (OBE and SSE) are defined at the finished grade level p
of the nuclear power plant structures.
This is in contradiction with the current Standard Review Plan 3.7.1, Revision 1 and Appendix A to 10 CFR 100 which requires that the design motion be applied at the foundation level.
The applicant is required to comply with this position and provide necessary analyses for all Category I structures.
Until the problem of design ground motion or seismic input is satisfactorily resolved, this is considered as open issue.
The synthetic time-history motions are scaled to 0.12 g and 0.20 g to obtain respectively the OBE and SSE design time-histories.
The response spectra obtained in the free field at the foundation level are compared with 60% of the design response spectra as stipulated in Regulatory Guide 1.60 instead of tha full design response spectra and are therefore unacceptable.
Until the problem of synthetic time history is resolved, we consider this as an open issue.
The specific percentage of critical damping values used in the seismic analysis of Category I structures, systems and components are in conformance with Regulatory Guide 1.61.
09/26/84 3-7 V0GTLE SER INPUT - SEC. 3
9;
'L Pebding resolution of the above oper# issues, a satisfactory review of the design report to be submitted in November, 1984, and the outccme of the design audit scheduled in December, the following conclusion will apply:
The applicant has met the recommendations of Standard Review Plan 3.7.1 Revision 1, the relevant requirements of GDC 2, end Appendix A to 10 CFR Part 100 by appropriate consideration for loads g nerated by the most severe earthquake recorded for the site, as defined in TSAR Section 2.5, with an appropriate margin and considerations for two levels of earthquakes--the safe shutdown earthquake (SSE) and operating basis earthquake'(OBE).
The applicant has met these requirements by the use'o'f the methods and procedures indicated below.
The seismic design response spect"ra (08E and SSE) applied in the design of seismic Category I structures, systems, and components comply with the recom-mandations of Regulatory Guide 1.60.
The specific percentage of critical damping values used in the seismic analysis of Category I structures, systems, and components are in conformance with Regulatory Guide 1.61.
The artifical (B) synthetic timo history used for seismic design'of CategoryiI plant structures, systems, and components is adjusted in amplitude and frequency content to obtain response spectra that envelope the design response spectra specified for the site.
Conformance with the recommendations of Regulatory Guides 1.60 and 1.61 assures that the seismic inputs to Category I structures, systems,
.and components are adequately defined so as to form a conservative buis for the design of such structures, systems, and components to withstand seismic loadings.
372 Seismic System Analysis
~'
v Combined with Section 3.7.3
.q'
'~
i 3.7.3 Seismic Subsystem An'alysh The ' cope of review of thy seismic system and subsystem analysis for the plant i
s includedtheseismicanalysismethodsforallCategoryIstructures, systems, f.
l-
' 09/26/84 5
3-8 V0GTLE SER INPUT - SEC. 3 3,
s s
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+
and components.
It included review of procedures for modeling, seismic soil-
^
)
structure interaction, development of floor response spectra, inclusion of torsional effects, evaluation of Category I structure overturning, and deter-mination of composite damping.
The review has included design criteria and procedures for evaluation of the interaction of non-Category I structures and piping with Category I structures and piping and the effects of parameters variations on floor response spectra.
The review has also included criteria and seismic analysis procedures for Category I buried piping outside containment.
The system and subsystem analyses are performed by the applicant on an elastic and linear basis.
Time history methods form the bases for the analyses of all major Category I structures, systems, and components.
When the modal response spectrum method is used the methods used in combining modal responses are in conformance with the Regulatory Guide 1.92.
The square root of the sum of the squares of the maximum codirectional responses is used in accounting for three components of the earthquake motion for both the time history and response spectrum methods.
Floor spectra inputs to be used for design and test verifi-7" cations of structures, systems, and components are generated from the time
',%,,, )history method and they are in conformance with the position of Regulatory Guide 1.122.
A vertical seismic system dynamic analysis is employed for all structures, systems, and components where analyses show significant structural amplification in the vertical direction.
Torsional effects and stability against overturning are considered.
A coupled structure and soil model is used to evaluate soil-structure interaction effects upon seismic responses.
The lumped parameter method is used for modeling of the structures.
The finite boundary methods are used for modeling of the supporting soil.
In the soil-structure interaction analysis, the applicant has not demonstrated compliance with the requirements of Sections 3.7.1 and 3.7.2 of the Standard Review Plan Revision 1 - July 1981.
To comply with the SRP requirements the applicant should show that:
1.
The design ground motion has been applied in the free field at the foundation level of the plant structure.
09/26/84 3-9 V0GTLE SER INPUT - SEC. 3
e i
2.
The impedance (half-space) method has been used to obtain floor response spectra.
t 3.
Comparisons have been made between the use of the impedance (half-space) and the finite boundary (finite element) methods.
4.
Envelope of results of the two methods has been used for design,of' Category I structures, systems and components.
i 5.
The confirmatory study and sensitivity study have confirmed the conserva-
~
tism in the analytical method used by the applicant.
6.
The acceptance criteria of Standard Review Plan 3.7.1 and 3.7.2 Rev. 1 7* (July 1981) have been satisfied.
< Information on significant natural frequencies of major Category I structures as required by Section 3.7.2.2 of the Standard Format and Content of Safety -
g Analysis Reports for Nuclear Power Plants has not been provided.
=
j Pending resolution of the above open issues, a satisfactory review of the design report,to be submitted in November, 1984, and the outcoke!of the design audit scheduled in' December, the following conclusien will apply:
The staff concludes that the plant design is acceptable and meets the recom-mendations of SRP 3.7.2 and 3.7.3 and the requirements of GDC 2 and Appendix A to 10 CFR Part 100.
The conclusion is based on the following:
The applicant has met the requirements of GDC 2 and Appendix A to 10 CFR Part 100 with respect to the capability of the structures to withstand the effects o'f the earthquakes so that their design reflects 1.
appropriate consideration,for the most severe earthquake recorded for the site with an appropriate' margin (GDC 2); consideration of two levels of earthquakes (Appendix A,610'CFR Part 100);
r
?
09/26/84 3-10 V0GTLE SER INPUT - SEC. 3 4
=,sh-
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2.
appropriate combination of the effects of normal and accident conditions with the effect of the natural phenomena; and 3.
the importance of the safety functions to be performed (GDC 2); the use of a suitable dynamic analysis or a suitable qualification test to demon-strate that structures, sytems, and components can withstand the seismic and other concurrent loads, except where it can be demonstrated that the use of an equivalent static load method provides adquate consideration (Appendix A, 10 CFR Part 100).
The applicant has met the requirements of. item 1 listed above by use of the acceptable seismic design parameters, as per SRP Section 3.7.1.
The combina-tion of earthquake-resulted loads with those resulting from normal and accident conditions in the design of Category I structures as specified in SRP Sections 3.8.1 through 3.8.5 will be in conformance with item 2 listed above.
The staff concludes that the use of seismic structural analysis procedures and j::rts criteria delineated above by the applicant provides acceptable bases for the
)
. seismic design, which are in conformance with the requirements of item 3 listed above.
'3.7.4 Seismic Instrumentation Program The type, number, location, and utilization of strong motion accelerographs to record seismic events and to provide data on the frequency, amplitude, and phase relationship of the seismic response of the containment structure comply with Regulatory Guide 1.12.
Supporting instrumentation is being installed on Category I structures, systems, and components in order to provide data for.
the verification of the seismic responses determined analytically for such Category I items.
The applicant stated that the details of the seismic instrumentation inservice surveillance program will be provided in the Technical Specifications. There-fore, subject to the review and acceptance of this item in the Technical Specifications, the following conclusion will apply:
09/26/84 3-11 V0GTLE SER INPUT - SEC. 3
. _. ~.
t The staff concludes that the seismic instrumentation system provided for the plant is acceptable and meets the requirements of General Design Criteria 2, 10 CFR Part 100,-Appendix A and 10 CFR Part 50, S 50.55a.
This conclusion is based on the following:
The applicant has met the requirements of 10 CFR Part 100, Appendix A by pro-viding the instrumentation that is capable of measuring the effects of an earthquake which meets the requirements of GDC 2.
The applicant has met the requirements of 10 CFR 50.55a by providing the inservice inspection program that will verify operability by performing channel checks, calibrations, and functional test at acceptable intervals.
In addition, the installation of the specified seismic instrumentation in the reactor containment structure and other Category I structures, systems, and components constitutes an acceptable program to record data on seismic ground motion as well as data on the fre-quency and amplitude relationship of the seismic response of major structures and systems.. A prompt readout of pertinent data at the control room can be expected to yield sufficient information to guide the operator on a timely gfg basis for the purpose of evaluating the seismic response in the event of an earthquake.
Data obtained from such installed seismic instrumentation will be sufficient to determine that the seismic analysis assumptions and the analyti-cal model used for the design of the plant are adequate and that allowable stresses are not exceeded under conditions where continuity of operation is
- intended.
Provision of such seismic instrumentation complies with Regulatory Guide 1.12.
3.8.1 Concrete Containment The containment consists of a prestressed reinforced concrete cylinder and hemispherical dome supported on a flat, conventionally reinforced concrete basemat with a central cavity and instrumentation tunnel to house the reactor vessel.
The inside diameter of the containment cylinder is 140 feet, and the cylinder wall and dome are both 3 ft. 9 in. thick.
The foundation consists of a circular basemat which is 154 ft. 6 in. in diameter and 10 ft. 6 in. thick.
The "inside face of the containment is lined with steel plates welded together to form a.leaktight barrier.
The liner is typically 1/4 in. thick, thickened
, p.
09/26/84 3-12 V0GTLE SER INPUT - SEC. 3
-..-..a
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O The prestressed reinforced concrete containment is designed for a pressure load of 52 psi resulting from the design base accident, and is designed and constructed to the requirements of the American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code,Section III, Division 2, 1975 Edition through the Winter 1975 Addenda, Article CC-3000 only.
The containment steel liner is designed following the analysis methods and procedures of BC-TOP-1.
The containment ultimate capacity will be calculated and presented in the containment design report.
Pending review and acceptance of the des.ign report to be submitted in November, 1984, and the outcome of the design audit scheduled in December, the following lP'q conclusion will apply:
The staff finds that the containment design is acceptable.
This conclusion is based on the following:
1.
The applicant has met the requirements of Section 50.55a and GDC 1 with respect to ensuring that the concrete containment is designed, fabricated, erected, constructed, tested, and inspected to quality standards commen-surate with its safety function to be performed by meeting the guidelines of Regulatory Guides and industry standards indicated below.
2.
The applicant has met the requirements of GDC 2 by designing the concrete containment to withstand the most severe earthquake that has been estab-lished for-the site with sufficient margin and the combinations of the effects of normal and accident conditions with the effects of environ-mental loadings such as earthquakes and other natural phenomena.
9 09/26/84 3-13 V0GTLE SER INPUT - SEC. 3 s
7^=
s 3.
The applicant has met the requirements of GDC 4 by ensuring that the design of the concrete containment is capable of withstanding the dynamic effects associated with missiles, pipe whipping, and discharging fluids.
4.
The applicant has met the requirements of GDC 16 by designing the concrete containment so that it is an essentially leaktight barrier to prevent the i
uncontrolled release of radioactive effluents to the environment.
L 5.
The applicant has met the requirements of GDC 50 by designing the concrete containment to accommodate, with sufficient margin, the design leakage rate and calculated pressure and temperature conditio'ns resulting from accident conditions, and by ensuring that the design conditions are not exceeded during the full course of the accident condition.
In meeting these design requirements, the applicant has used the recommendations of regulatory guides and industry standards indicated below.
The criteria used in the analysis, design, and construction of the concrete
'Q containment structure to account for anticipated loadings and postulated
.,f conditions that-may be imposed upon the structure during its service lifetime are in conformance with established criteria, and with codes, standards, guides, and specifications acceptable to the staff.
These include meeting the intent of Regulatory Guides 1.31 and 1.55 and ASME Boiler and Pressure Vessel Code,'Section III, Division 1 and Division 2.
The use of these criteria as defined by applicable codes, standards, guides, and specifications, the loads and loading combinations; the design and analysis procedures; the structural acceptance criteria; the materials, quality control
_ programs, and special construction techniques; and the testing and inservice surveillance requirements provide reasonable assurance that, in the event of winds, tornadoes, earthquakes and various postulated accidents occurring within and outside the containment, the structure will withstand the specified design conditions without impairment of structural integrity or safety function of limiting the release of radioactive material.
=
09/26/84 3-14 V0GTLE SER INPUT - SEC. 3
s.
i 3.8.2 Steel Containment Not Applicable.
3.8.3 Concrete and Structural Steel Internal Structures The internal structures are those concrete or steel structures inside of the containment pressure boundary which support the reactor coolant system components and related piping systems and equipment.
The concrete structures also provide radiation shielding.
The internal structures consist of the primary shield wall, secondary shield and pressurizer compartment walls, refueling canal walls, operating floor, intermediate slabs and platforms, and the polar crane runway girders.
The major code used in the design of concrete internal structures was American Concrete Institute Standard 318-71, " Building Code Requirements for Reinforced Concrete." For steel internal structures, the American Institute of Steel Construction Specification, " Specification for the Design, Fabrication and
,/
Erection of Structural Steel for Buildings," was used.
SRP Section 3.8.3 specifies that the code to be used in the design of concrete internal structures is American Concrete Institute Standard 349 as augmented by Regulatory Guide 1.142.
The applicant addressed that the differences between ACI 349 and ACI 318 are minor, except for the load combination equa-tions which, in the case of Vogtle Electric Generating Plant, are in accor-dance with_the Standard Review Plan.
Thus, the design procedures and construc-tion practices delineated in the FSAR ensure that the structure will withstand the specified design conditions without impairing structural integrity or the performance of required safety functions.
Pending review and acceptance of the design report to be submitted in November, 1984, and the outcome of the design audit scheduled in December, we conclude that the design of containment internal structures is acceptable and meets the relevant requirements of 10 CFR $50.55a and GDC 1, 2, 4, 5 and 50.
This conclusion is based on the following:
09/26/84 3-15 V0GTLE SER INPUT - SEC. 3
1.
The applicant has met the requirements of Section 50.55a and GDC 1 with respect to assuring that the containment internal structures are designed, fabricated, erected, constructed, tested, and inspected to quality stan-dards commensurate with its safety function to be performed by meeting the guidelines of regulatory guides and industry standards indicated below.
2.
The applicant has met the requirements of GDC 2 by designing the containment internal structure to withstand the most severe earthquake that has been established for the site with sufficient margin and the combinations of the effects of normal and accident conditions with the effects of environmental loadings such as earthquakes and other natural phenomena.
3.
The applicant has met the requirements of GDC 4 by ensuring that the design of the internal structures is capable of withstanding the dynamic effects associated with missiles, pipe whipping, and discharging fluids.
i.&
4.
The applicant has met the requirements of GDC 5 by demonstrating that structures, systems, and components are not shared between units or that if shared they have demonstrated that sharing will not impair their ability to perform their intended safety function.
5.
The applicant has met the requirements of GDC 50 by designing the containment internal structures to accommodate, with sufficient margin, the design leakage rate, and calculated pressure and temperature condi-tions resulting from accident conditions and by assuring that the design conditions are not exceeded during the full course of the accident condi-tion.
In meeting these design requirements, the applicant has used the recommendations of regulatory guides and industry standards indicated below.
The criteria used in the design, analysis, and construction of the containment
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internal. structures to account for anticipated loadings and postulated condi-tions that may be imposed during their service lifetime are in conformance with establishment criteria, and with codes, standards, and specifications l
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acceptable to the staff.
These include meeting the intent of Regulatory Guides 1.10, 1.15, 1.55, 1.94, 1.142; ACI-318.71, ASME Code,Section III, Division 1, Subsection NF; and AISC, " Specifications for the Design, Fabri-cation, and Erection of Structural Steel for Buildings."
The use of these criteria as defined by applicable codes, standards, and specifications, the loads and loading combinations; the design and analysis prucedures; the structural acceptance criteria; the materials, quality control programs, and special construction techniques; and the testing and inservice surveillance requirements provide reasonable assurance that, in the event of earthquakes and various postulated accidents occurring within the containment, the interior structures will withstand the specified design conditions without impairment of structural integrity or the performance of required safety functions.
3.8.4 Other Category I Structures p.,
Category I' structures other than containment and its interior structures are all of structural steel and concrete.
The structural components consist of slabs, walls,. beams, and columns.
The major code used in the design of con-crete Category I structures is the ACI 318-71.
For steel Category I structures, the AISC, " Specification for the Design, Fabrication, and Erection of Structural Steel for Buildings," is used. The applicant addressed that the differences between ACI 349 and ACI 318 are minor, except for the load combination equations which, in the case of Vogtle Electric Generating Plant, are in accordance with the Standard Review Plan.
Thus, the design procedures and construction prac-tices delineated in the FSAR ensure that the structure will withstand the specified design conditions without impairing structural integrity or the
. performance of required safety functions.
Pending review and acceptance of the design report to be submitted in November, 1984, and the outcome of the design audit scheduled in December, we conclude that the design of safety-related structures other than containment is accept-able and meets the relevant requirements of 10 CFR 50.65a and GDC 1, 2, 4, and 5.
This conclusion is based on the following:
s 09/26/84 3-17 V0GTLE SER INPUT - SEC. 3 e
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s 1.
The applicant has met the requirements of Section 50.55a, and GDC 1 with respect to assuring that the safety-related structures other than contain-ment, are designed, fabricated, erected, constructed, tested and inspected to quality standards commensurate with its safety function to be performed by meeting the guidelines of regulatory guides and industry standards indicated below.
2.
The applicant has met the requirements of GDC 2 by designing the safety-related. structures other than containment to withstand the most severe earthquake that has been established for the site with sufficient margin and the combinations of the effects of normal and accident conditions with the effects of environmental loadings such as earthquakes and other natural phenomena.
3.
The applicant has met the requirements of GDC 4 by ensuring that the design of the safety-related structures is capable of withstanding the dynamic effects associated with missiles, pipe whipping and discharging
,.o fluids.
-s 4.
The apolicant has met the requirements of GDC 5 by demonstrating that structures, systems, and components are not shared between units or that if shared they have demonstrated that sharing will not impair their ability to perform their intended safety function.
5.
The applicant has met the requirements of Appendix B because his quality assurance program provides adequate measures for implementing guidelines relating to structural design audits.
The criteria used in the analysis, design, and construction of all the plant Category I structures to account for anticipated loadings and postulated conditions that may be imposed during their service lifetime are in conformance with established criteria, and with codes, standards, and specifications acceptable to the staff.
These include meeting the intent of Regulatory
~
Guides 1.10, 1.15, 1,91, 1.94, 1.142; ACI 318-71; and AISC, " Specifications for the Design, Fabrication, and Erection of Structural Steel for Buildings."
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e 09/26/84 3-18 V0GTLE SER INPUT - SEC. 3
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The use of these criteria as defined by applicable codes, standards, and specifications, the load and loading combinations; the design and analysis procedures. the structural acceptance criteria; the materials, quality control programs, and special construction techniques; and the testing and inservice surveillance requirements provide reasonable assurance that, in the event of winds, tornadoes, earthquakes and various postulated accidents occurring within and outside, the structures will withstand the specified design condi-tions without impairment of structural integrity or the performance of required safety functions.
3.8.5 Foundations Foundations of Category I structures are described in FSAR Section 3.8.5.
Primarily, these foundations are reinforced concrete and of the mat type.
The-major code used in the design of the concrete mat foundations is ACI 318-71 Code. These concrete foundations have been designed to resist various combi-nations of dead loads; live loads; environmental loads including winds, fc 73 tornados, OBE, and SSE; and loads generated by posulated ruptures of high energy pipes.
The design and analysis procedures that were used for these Category I founda-tions are the same as those approved on previously licensed applications and, in general, are in accordance with procedures delineated in the ACI 318-71 Code.
The various Category I foundations were designed and proportioned to remain within limits established by the staff. under the various load combina-tions.
These limits are, in general, based on the ACI 318-71 Code and on the AISC specification for concrete and steel structures, respectively, modified as appropriate for load combinations that are considered extreme. The appli-cant has provided an assessment and justifications of all deviations of his design from the applicable requirements of ACI 349 code as augmented by Regulatory Guide 1.142.
The staff has reviewed the applicant's submittal and find it acceptable.
09/26/84 3-19 V0GTLE SER INPUT - SEC. 3
a V
The materials of constructions, their fabrication, construction and installa-tion are in accordance with the ACI 318-71 Code and AISC Specification for concrete and steel structures, respectively.
The criteria that were used in the analysis, design, and construction of all the plant Category I foundations to account for anticipated loadings and postulated conditions that may be imposed upon each foundation during its service lifetime are in conformance with established criteria, and with codes, standards, and specifications acceptable to the NRC staff.
Pending the resolution of the abcve open items, we conclude that the design of the seismic Category I foundations is acceptable and meets the relevant require-ments of 10 CFR 50.55a ancf GDC 1, 2, 4, and 5.
This conclusion is based on the following:
1.
The applicant has met the requirements of Section 50.55a and GDC 1 with respect to assuring that the seismic Category I foundations are designed,
,c7-fabricated, erected, constructed, tested, and inspected to quality stan-5 dards commensurate with its safety function to be performed by meeting the guidelines of regulatory guides and industry si.6r. dart indicated below.
2.
The applicant has met the requirements of GDC 2 by designing the seismic Category I foundation to withstand the most severe earthquake that has been established for the site with sufficient margin and the combinations of the effects of normal and accident conditions with the effects of environmental loadings such as earthquakes and other natural phenomena.
3.
The applicant has met the requirements of GDC 4 by assuring that the design of the seismic Category I foundations is capable of withstanding the dynamic effects associated with missiles, pipe whipping, and dis-charging fluids.
4.
The applicant has met the requirements of GDC 5 by demonstrating that
' structures, systems, and components are not shared between units or that if shared they have demonstrated that sharing will not impair their
. ability to perform their intended safety function.
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. 35?l';.
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The criteria used in the design, analysis, and construction of the plant seismic Category I foundations to account for anticipated loadings and postu-lated conditions that may be imposed upon each foundation during its service lifetime are in conformance with established criteria, and with codes, stan-t dards, and specifications acceptable to the Regulatory staff.
These include meeting the positions of Regulatory Guide 1.142 and industry standards ACI-318-71, AISC, " Specifications for the Design, Fabrication, and Erection of Structural Steel for Buildings."
The use of these criteria as defined by applicable codes, standards, and s,,ecifications, the loads and loading combinations; the design and analysis procedures; the structural acceptance criteria; the materials, quality control, and special construction techniques; the testing and inservice surveillance requirements provide reasonable assurance that, in the event of winds, torna-does, earthquakes and various postulated events, seismic Category I foundations will withstand the specified design conditions without impairment of structural integrity or the performance of required safety functions.
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3.8.6 Structural Audit From December 3 through December 7, 1984, the staff will meet with the appli-cant and his consultants to conduct the st'ructural audit.
The audit covered each major safety-related structure at the Vogtle Electric Generating Plant.
- The staff will conduct the audit in order to accomplish the following objectives:
1.
To investigate in detail how the applicant has implemented the structural and seismic design criteria that he committed to use, prior to obtaining construction permits for the facility.
2.
Te verify that the key structural and seismic design and the related calculations have been conducted in an acceptable way.
09/26/84 3-21 VCGTLE SER INPUT - SEC. 3
T e.. ;:
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s. -
3.
'To identify and assess the safety significance of those areas where the plant structures were designed and analyzed using methods other than those recommended by the NRC Standard Review Plan (NUREG-0800).
Results of the audit will be reported and evaluated in the final safety evaluation reports or supplements.
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p.
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