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- *4 NUCLEAR REGULATORY COMMISSION WASHINGTON, D. C. 20555 yy Il0V 21 1977 Docket No. 50-424/425 MEMORANDUM FOR:
J. Carl Stepp, Chief, Geosciences Branch, DSE FROM:
Lyman W. Heller, Leader, Geotechnical Engineering Section, Geosciences Branch, DSE
SUBJECT:
INSPECTION OF EXCAVATION - V0GTLE 1 & 2 On November 16, 1977, I inspected the excavation for foundations of the Vogtle Plant, Unit 1 & 2.
The applicant's personnel involved in this inspection included: Jim Baily (Southern Services), Walt Ferris, Mike Thakar, Cole McClure and Warren Pederson (all of Bechtel),
and Larry Bryant (Georgia Power).
Plant grade is to be at elevation 220 ft.
Excavation is completed to and into a competent, unweathered, flat-lying (dip of about 1 percent to the east) formation some 90 to 110 ft. below plant grade. Except for a few thin stringers of indurated marl (limestone), the weathered and unweathered marl was removed with backhoes and rubber-tired pans.
Rock is at a depth of about 1000 ft.
Most of the exposed marl had been covered by construction activities - the concrete bottom of the deep auxiliary. building foundation, and the backfill to support reactor and turbine buildings. Exposures on the peripheral slopes of the excavation had been obliterated by riprap and coarse filter stone used to alleviate erosion of the slope material into the excavation.
A perimeter ditch and sump at the base of the excavations is being used to dewater the overburden and to drain the excavation. Heave monunents, established prior to excavating the overburden, have been used to establish the total heave of the top of the marl at about 2 inches. Bore-holes into and through the marl are reportedly grouted shut. A cased water well previously placed through the marl is still in place and is said to be the source for makeup water supplying the makeup service water storage basins for the seismic Category I mechanical draft cooling towers.
Seismic Category I structural backfill was beJng placed in the excavation in 6 irich lifts (loose) directly on the freshly exposed marl and compacted
.with four passes of steel drum vibratory rollers which weigh about 15,000
,. pounds. CP compaction critoria is said to be attained. We inspected stock-piles of safety-class fill and one working borrow area. Considerable l
cementation of borrow sands was evident. It was reported that an adequate 8505280287 841015 htLy
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NOV 2 1 577 supply of geod (criteria) quality f'ill ints expected to -be available from on-site borrow areas.
t A Mr. Dan Cordell (Bechtel) arrived at the Augusta airport on the evening.
- of November'16, 1977, with draft geologic maps of-the Vogtle excavation.
Because the vertical excavation exposures were no longer visible at the site, we reviewed the mapping and correlated photographic. logging in
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some detail. The map scale is one inch for each five feet of exposure.
M p detailing in the auxiliary building foundation area, which penetrates a
the earl to elevation 109 ft., was satisfactory. Representations of the stratigraphy on the excavation slopes were also adequate. The photo-graphic logs were unusually complete and detailed.but will not be
. submitted as part of the docket information. Color photographs of fresh marl cores were reviewed.
, In summary, the inspection revealed no evidence of varped marker beds or
.of offsets, shears, folds and deformation zones within the excavation.
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Groundwater control appeared adequate and backfill quality measured up j'
to CP commitments. All safety-related, facilities are to be founded on or in earl or compacted backfill. No geological or geotechnical items adverse to the safety of the plant were revealed.during this inspection.
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bbN Lyman M. Heller, Leader Geotechnical Engineering Section Geosciences Branch Division of Site safety and Environmental Analysis cc:
W. Gammill J. Knight L. Hulman
'1 R. Hofmann L. Heller s
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Bechtel Power Cor ation Engineers - Constructors I y/
12400 East imperial Highway Norwalk. California 90650 Io so ed. TEWmL weEX. LOS ANGRES. CALFOMA 90000 TELEPHONE (213)e644011 December 15, 1977 Mr. W. M. Moore Project Administration Manager Georgia Power Company P. O. Box 4545 Atlanta, Georgia 30302
Subject:
Georgia Power Company Alvin W. Vogtle Nuclear Plant Bechtel Job 9510-001 Conference Notes CN325 Supplement No. 3 to PSAR Chapter 3.7 File X7M00.0-S3, X7M03.7, X2BR01 Log BG 4298
Dear Mr. Moore:
Enclosed are the Bechtel Conference Notes CN325 on the Supplement No. 3 to PSAR Chapter 3.7 meeting held on November-15, 1977 at the Nuclear Regulatory Commission, Bethesda, Maryland, with Southern Company Services, Georgia Power Company, Riclear Regulatory Commission and Bachtel Power. Corporation participating.
Very truly yottra, BECHTEL POWER CORPORATION
{ J. D. Duffin '
Project Encffneer Los Angeles Power Division RCC/MRT/ms Enclosure cc:
See attached distribution list l
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I DISTRIBUTION LIST Georgia Power Company Bechtel Power Corporation D. E. Dutton D. S. Jagannathan H. P. Walker R. C. Chao s
W. M. Johnston, Jr.
W. R. Ferris. (S.F. Office)
R. E. Conry W. R. Holland M. R. Thakar Southern Company Services Nuclear Regulatory Commission R. A. Thomas I. Sibweil O. Batum D. C. Jeng J.'A. Bailey S. P. Chan G. F. Trowbridge P. T. Kuo S. A. Treby L. W. Heller R. Lipinski D. Lynch A. T. Cardone
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e ALVIN W. VOGTLE NUCLEAR PLAliT BECHTEL JOB 9510-001 UNITS 1 AND 2 CONFERENCE NOTES CN325 Meeting Held:
November 45, 1977 at NRC, Bethesda, Maryland
Subject:
Supplement No. 3 to PSAR Chapter 3.7 File:
X7M00.0-S3, X7M03.7, X2BR01 Prepared by:
R. C. Chao Present:
BECHTEL POWER CORPORATION SOUTHERN COMPANY SERVICES W. R. Holland R. A. Thomas M. R. Thakar O. Batum W. R. Ferris (S.F. Office)
J. A. Bailey D. S.'Jagannathan G. F. Trowbridge (Counsel)
R. C. Chao NUCLEAR REGULATORY COMMISSION GEORGIA POWER COMPANY I. Sihweil L. W. Heller D. E. Dutton D. C. Jeng R. Lipinski S. P. Chan D. Lynch P. T. Kuo A. T. Cardone S. A. Treby Purpose of Meeting The purpose of this meeting was to present to the NRC staff an outline of the proposed supplement to the Vogtle Nuclear Plant PSAR, Chapter 3.7, relative to the analytical procedure of seismic anaysis of deeply embedded structures.
Opening Statements 1.
1br. D. Lynch of NRC stated that:
- 1) no action will be taken by the NRC staff until the supplement was. formally submitted; 2) NRC staff was not ready to approve or disapprove in the meeting any proposed changes; 3) no decision will be made by the NRC staff in the meeting whether pre-notice was required.
1 CN325 2.
Mr. R. A. Thomas stated that the main purpose of the meeting was to have a' good communication between VNP project and the NRC staff so that understanding can be reached on the proposed supplement.
Mr. Thomas also pointed out that " time" was of the essence.
All VNP equipment is either on order or being procured using the current seismic analysis results.
Any update in the analysis procedure needs to be incorporated in a timely manner onto our engineering activity or face the consequences of costly delay.
A quick turn-around in reviewing this supplement by the NRC staff will be. deeply appreciated.
Mr. Thomas also remarked that the meeting will be divided in two parts:
Technical presentation and discussion on legal require-ments.
Technical Presentation and Discussion 1.
R. C..Chao of BVNP presented the outline of the proposed supple-ment as follows:
A.
Regarding seismic input, the VNP's current commitment in the PSAR for design spectra is the modified Newmark curve.
In the supplement, VNP proposes to use Reg.
Guide 1.60 design spectra.
Similarly, Reg. Guide 1.61 is proposed to replace the current commitment for damping.
These were requested by the NRC. staff in the September 27 meeting.
As mentioned in the September meeting, it is also proposed that input motion be applied at finished grade level instead of at the foundation level.
B.
Regarding the method of analysis, it is proposed that the computer code FLUSH be used instead of LUSH.
VNP will also perform 3-dimensional analysis for structures using interacted motion as input.
Torsional and coupling (with NS3S equipment) effects shall be considered in the analysis.
This'was also requestd by NRC staff.
C.
Regarding soil properties, Seed and Idriss standard curves for strain-dependency were used in the original PSAR.
Data have been developed from testing of compacted 1
backfill and standard curves have been modified for the site soil condition.
These curves are included in the supplement.
The variation of soil properties will be considered in the analysis.
The range of variation, as recommended by Prof. H. B. Seed, is that the mean values of shear moduli be-multiplied by 1.5 and divided by 1.5.
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CN325 2.
R. C. Chao also pointed out that even with this variation, the motion at the base of structures will not envelop completely the 60% design spectra.
NRC staff stated that the 60% design spectra must be enveloped.
3.
Mr. P. T. Kuo asked what motion will BVNP use as input to the 3-D models of structures.
R. C. Chao responded that there were methods available to generate an average set of motions from motions of several nodal points.
One of the methods proposed by Prof. Lysmer is the least-square-fit technique.
However, VNP is currently investigating various alternatives for this application.
NRC staff requested that VNP should describe the method to be used for this application in the supplement.
4.
Mr. L. W. Heller of NRC asked how the strain-dependency curves were developed.
Mr. W. R. Ferris responded that strain-dependency curves for compacted backfill have been developed by testing of samples taken from 93% and 95% compaction backfill but will be verified when tests are performed on 97% compaction backfill.
The strain-dependency curves for marl and lower sand stratum were recommended by Prof. Seed.
Backup information from Prof. Seed can be obtained.
5.
Mr. R. A. Thomas stated that VNP seismic analysis had been based on two-component earthquake and it was VNP's intention to maintain this basis.
NRC staff responded that three-component earthquake using Reg. Guide 1.92 for combination of responses must be used in conjunction with the current proposed changes.
Di~scussion on Legal Requirements 1.
Mr. G. F. Trowbridge (SCS legal counsel) stated that the proposed changes in the supplement are in conformance with current NRC regulatory. position and therefore should not warrant a pre-notice.
If NRC staff deem it is necessary to have pre-notice, VNP requests that a prompt action should be taken so as to avoid delay in the construction activity.
Mr. S. A. Treby of NRC responded that NRC staff will review the eupplement and then decide whether pre-notice is required.
2.
Mr. R. A. Thomas requested NRC staff to review the preliminary copy of supplement which had been handed to NRC personnel to shorten the decision making period.
The formal submittal of Supplement No. 3 will be transmitted by November 23, 1977.
'.CN325 -
Conclusion 1.-
VNP PSAR Supplement No. 3 will be formally subnitted to NRC without any changes from the preliminary copy.
(Only typo graphyical errors will be corrected).
The submittal date will be November 23,-1977.
2.
'Any revision of'the supplement will be handled by responses to NRC
. questions.
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R. C. Chao RCC/MRT/ms
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