ML19211C619
| ML19211C619 | |
| Person / Time | |
|---|---|
| Site: | Vogtle, 05000426, 05000427  |
| Issue date: | 12/28/1979 |
| From: | Rolonda Jackson Office of Nuclear Reactor Regulation |
| To: | Rubenstein L Office of Nuclear Reactor Regulation |
| References | |
| NUDOCS 8001140064 | |
| Download: ML19211C619 (3) | |
Text
._ _ ___
~
n sVY.
pn nsa ff jo,,
UNITED STATES c,
g NUCLEAR REGULATO3Y COMMISSION y
E WA$mNGTON, D. C. 20655 g
r
\\..... #
DEC 2 9 1979 MEMORANDUM FOR:
L. Rubenstein, Acting Chief Light Water Reactors Branch No. 4, DPM FROM:
Robert E. Jackson, Chief Geosciences Branch, DSS
SUBJECT:
REVIEW 0F LICENSE REQUEST TO RESUME SPECIFIC ITEMS OF WORK PLANT NAME: Vogtle Units 1 & 2 LICENSING STAGE: Post CP DOCKET NUMBERS: 50-424/427 MILESTONE NUMBER: R-18 TAC NUMBER:
5347 RESPONSIBLE BRANCH: LWR-4; C. Stahle, LPM STATUS: Awaiting additional information In a letter and amendments dated December 6, 1979, from D. Dutton, GPC to J. O'Reilly, NRC, the licensee requested permission to resume your of the items of work which had been restricted by NRC letter dated November 29, 1979 from J. O'Reilly, NRC to J. Miller, GPC. We have reviewed the information submitted to us by the licensee and our coments on the four specific items are as follows:
1.
Installation of Piezometers within the Powerblock Excavation The methods of installing and monitoring both the short term and long term piezometers are acceptable. We emphasize the need to provide casiny in the piezometer holes to prevent collapsing and possible deterioration o' surrounding soils. Monitoring of the piezameters should start immediately after they are installed. We request submittal of the licensee's plans for abandoning the temporary piezometers for our review.
2.
Installation of a Supplemental Dewatering System The licensee has raquested permission to install a series of well doints between the auxiliary building and the control building for temporary dewa:ering during construction.
In discussions with the licensee we have expressed the opinion that a dewatering system in the selected area may not be necessary or may not be adequate, depending on the subsurface water regime. We have no objections to the licensee proceeding, at his own risk, with the temporary installation of an approved dewatering system. However, the proposed method of installing the well 1743 309 8001140 b
DEC 2 e S79 L. Rubenstein points is not approved because of our concern for potential deterioration of the structural backfill, as discussed below.
The proposed well points will extend about 10 ft through controlled structural backfill to native marl soils. The backfill will support seismic Category I structures and thus there must be assurance that there is no loss in supporting capability of the structural backfill. The proposed method of installing the well points is to advance an 8-inch diameter casing by a combined jetting and driving technique. This method is a common drilling techniq e but is unacceptable in this situation because a) the jet dire:ts water downward and there is the possibility of loosening backfill material outside the casing.
b) the inner tube, acting as a combined jet and hamrnr, does not appear to be heavy enough to impact significant driving energy to the casing. The proposed installation procedure, therefore, cannot be considered to be comparable to thepreferred method of a driven casing cleaned out by washing.
c) the proposed method for checking to ensure that voids are not created outside the casing i:3 to compare the actual volume of filter material used to backfill the hole with the estimated volume of the drilled hole as the casing is renoved. However, there could be significant and detrimental loss of the structural backfill density outside the casing even though there were no measurable voids.
The licensee must submit, for our review and approval, a method of installing the well points which will ensure that no deterioration of the structural backfill occurs.
3.
Installation and Implementation of a Supplemental Settlement Monitoring System The proposed supplemental settlement monitoring system is acceptable and should be implemented as soon as possible.
4.
Reshapine of the Turbine Building South Backfill Slope The proposed dressing and protecting of slopes is acceptable and should proceed as soon as possible in the specified areas away from the centrol building.
I 1743 310
DEC 2 8 579 L. Rubenstein We require responses to the remaining requests for information outlined in my memo to you dated December 6, 1979, before we can recommend release of other This review is being perfcmed by Dr. Owen Thompson, Geotechnical items of work.
Engineering Section, Geosciences Branch, 055.
Robert E.
son, Chief Geoscien Branch Division of Systems Safety ec:
D. Vassallo S. Varga C. Stahle H. Thornburg R. Shewmaker J. O'Reilly C. Murphy F. Cantrell M. Hunt J. Harris J. Lenahan F. Schroeder J. Knight F. Schauer S. Chan L. Hulman W. Bivins T. Johnson R. Jackson L. Heller J. Kane L. Reiter
- 0. Thompson F. Williams POR Local POR l
1743 311
..