ML19296B269
| ML19296B269 | |
| Person / Time | |
|---|---|
| Site: | Vogtle  |
| Issue date: | 02/01/1980 |
| From: | Rolonda Jackson Office of Nuclear Reactor Regulation |
| To: | Rubenstein L Office of Nuclear Reactor Regulation |
| References | |
| NUDOCS 8002200351 | |
| Download: ML19296B269 (9) | |
Text
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FEB 011980 MEMORANDUM FOR:
L. Rubenstein, Acting Chief Light Water Reactors Branch No. 4, DPM FROM:
Robert E. Jackson, Chief Geosciences Branch, DSS
SUBJECT:
REVIEW 0F FOUNDATION CONSTRUCTION AND GROUNDWATER CONTROL MEASURES f'_ ANT NA.ME:
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. Stable, LPM STATUS: Awaiting additional information The attached report contains our review ccmments on the information provided to NRC by the licensee in letters dated December 6, 1979, December 12, 1979 and January 8, 1980 (D. Dutton, GPC to J. O'Reilly, NRC).
These letters respond to our request for information contained in my memorandum to you dated December 6, 1979 and transmitted to the licensee on December 10, 1979 (L. Rubenstein, NRC to Ehrensperger, GPC). The licensee's letters also respond to the Confirnation of Concurrence letter dated November 29, 1979 from J. O'Reilly, NRC to J. Miller, GPC.
In my memorandum to you dated December 28, 1979 and January 10, 1980 we approved the licensee's requests to resume specific items of work.. We have completed our review of the licensee's submittals and we now also approve the remainder of the licensee's requests in his January 8, 1980 submittal, subject to the following contingencies:
1.
All relevant soils and dewatering work will be performed under the direction of a qualified ge' technical engineer.
2.
Discharge from the well-point system will be monitored for soil content and pumping will be suspended if the soil content exceeds 5 parts per million.
3.
The investigative approach to the evaluation and correction of damage around Unit 2 tendon gallery foundations will also be applied to Unit 1 tendon gallery foundations at all locations where the existing grade is near foundation elevation.
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Grouting procedures will be more clearly explained io show that the required 5 inch seismic gap between Unit 1 tendon gallery and the auxiliary building will not be compromised.
5.
Evaluation and repair of damaged mud mats in the turbine building will follow the general procedures for other damaged mud nats.
6.
The licensee will verify that there are no safety related appurtenances under the Turbine building mud mat.
7.
The licensee will analyze and report safe set-back distances on temporary slopes for buildings located closer to the slope than that found by an imaginary 2:1 (horizcatal:vcetical) slope.
8.
The licensee will provide photographic documentation of repair operations.
Details of our review comments and approvals to resume spe:ific items of work are attached.
This review has been made by Dr. Owen Thompson, Geotechnical Engineering Section, Grosciences Branch, DSS.
Robert E. Jack n Chief Geosciences B a n Division of Systems Safety
Attachment:
As stated cc: w/o attachment D. Vassallo H. Thornburg S. Varga J. O'Reilly F. Schroeder cc: w/ attachment C. Stable L. Hulman R. Shewmaker W. Bivins C. Murphy T. Johnson F. Cantrell R. Jackson M. Hunt L. Heller J. Harris L. Reiter J. Lenahan
Plant Name:
Vogtle Units 1 & 2 Licensing Stage: Post CP Docket No:
50-424/427 Milestone No.: R-18 Tac No.:
5347 Responsible Branch: LWR-4, C. Stahle, LPM Reviewed by: Owen Thompson, Geotechnical Engineering Section GB, DSS
Subject:
Review of Foundation Construction and Water Control Measures In our memorandum dated December 6, 1979 (R. Jackson to L. Rubenstein) we requested eleven (11) items of informatien from the licensee. We have received and reviewed the licensee's responses dated December 6, 1979, Dec.
12, 1979 and January 8, 1980 (D. Dutton, GPC to J. O'Reilly, URC). The latest response also includes a request from the licensee to resume ten (10) items of work.
Summary of Previous Approvals to Resume Specific Items of Work In our memorandum dated December 28, 1978 (R. Jackson to L. Rubenstein) we approved the licensee's request to a) install piezometers b) install a supplemental settlement monitoring system c) reshape the turbine building south slope.
In our memorandum dated January 10, 1980 (R. Jackson to L. Rubenctriq) we approved the licensee's request to install the well point system (supplementai dewaterina syste-O in accordance with procedures outlined in the licensee's letter of December 12, 1979 (D. Dutton, GPC to J. O'Reilly, NRC) which specified that jetting was not to be usec for well point installation.
. At a meeting on January 9, 1980 between NRC GPC, Bechtel Power Corporation and Fugro Consulti, So ng Engineers the licensee presented his submittal dated January 8, 1980 and re ques 6ed immediate release to resume certain additional items of work We agreed to provide an early response.
We indicated that release would be contingent o licensee providing a geotechnical engineer at the n the earthwork and dewatering acti ities.
site durirg critical v
However, the licensee should be aware that theThe lice get.+.echnical engineer should have training and experience equivalent to at l for registration as a professional engiacer east the requirements Furthermore, the geotechnical engineer should be able to make independent professio during construction.
nal judgement decisions At the January 9, 1980 meeting the licensee als o comitted to monitor the discharge from the well point system to ensure no fines during pumping.
are removed Samples will be visually checked five (5) time the first 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> and then daily.
s in for I&E inspection.
Some of the samples will be retained If any visible soil particles are detected in a sa the sample will be tested in the l u. oratory tt
- mple, Cetermine tie exact soil content.
The pumping will be stopped if greater than 5 p million of soil particles are detected.
arts per acceptable.
We found these procedures to be After revier.ing the proposed dewatering system and available piezometer measurements we found that inadequate data had been obt i side of Loth tendon galleries. The licensee ins u llsd two a ned in the north (replacing ST-8 and installing ST-14A) Readings fro new short-tern piezometers m these piezometers are consistent with the other readings and thus the subsurfac been adequately described.
e water regime has Also, adequate settlement monuments are in place
. and we now approve the coninencement of pumping from the well-point system.
This approval was given verbally to I&E Region II on January 11, 1980.
The licensee requested approval to resume other items outlined in a January 7, 1980 inclusion to the licensee's submittai dated January 8, 1980.
Although our review was not complete we were able to approve specific items of work. O n January 18, 1980 we verbally informed I&E Region II d at the lice.nsee could proceed with the following items as itemized ir. the Jan.
7, 933 inclusion:
(1) Groundwater Dewatering System - Operation of the dewatering system.
(2) Control Bailding - Shafts 1 & 2 - Repair of erosien and completion of backfilling of slope to Turbine Building base slab elevation upon reading satisfactory groundwater levels. Moisture and density information will be provided the NRC prior to placement of additional permanent backfill.
(3) Between Unit No. 1 Tendon Gallery and Electrical Tunnel No. 1 - Excavation and repair of erosion damage north of N79 + 85 upon reading satisfactory groundwater levels. Moisture and density information will be provided the NRC prior to placement of additional pernanent backfill.
(7) f.uxiliary Building North Wel: - Excavation as required and rt.sumption of backfilling in this area upon reading satisfactory groundwater levels.
(1) initial Lor. crete Placeaent - Commence work in all areas where wori 5et not been initiated when backfill is tc base slaS elevaticns.
We find that the licensee has adequately described the sut' surface water conditions and has provided satisfactory descriptions of the methods to be used to evaltate and repair tha areas described at.ove.
Remaining Items Requiring NRC Approval to Resume Work The following items listed in the licensee's submittal of January 8, 1980 have not yet been adoressed by us:
. (4) Unit tio. 1 - Containment Area - Excavation of disturbed material and continuation of backfill inside Tendon Gallery upon reading satisfactory groundwater levels. Moisture and density information will be provided the f1RC prior to placement of additional permanent backfill.
(5) Unit tio. 2 - Containment Area - Excavation and further field testing upon reading satisfactory groundwater levels.
Upon completion of engineering evaluation, further submittals will be forwarded to the f1RC. The f1RC will be notified prior to any excavation work so they may be present, if desirec.
(6) Unit 1 Tendon Gallery - (Outside Perimeter) Excavation and repair of erosion areas upon reading satisfactory groundwater levels.
(8) Turbine Building - Continuation of all work in this area upon completion of rework of south slope and backfilling of area around Control Building - Shafts 1 & 2.
(9) Resumption of Concrete Work - Resumption of concrete work in (1) the Unit 1 Electrical Tunnel upon completion of backfilling to above base slab elevation on the east side and nortn side; (2.) the Unit 1 Containment and Tendon Gallery upon completion of repairs and backfilling to above Tendon Gallery Base Slab elevation; (3) the Unit II Electrical Tunnel upon completion of backfilling to above the base slab elevation.
Items 4, 5 and 6 are all related to the tendon galleries and our concern with these areas is that there could have been water flowing under the foundations and c;ncomitant erosion or deterioration of the fill soils supporting the foundations. The areas of concern are approximately from ST-14A to ST-13 and from ST-8 to ST-ll. After reviewing the licensee's submit:? h
5 we find that the licensee has provided as much information as can be provided at this time. The procedures specified for Unit 2 (item 5) are acceptable. However, the same investigative approach also is necessary for Unit 1, both inside and outside the tendon gallery (items 4 and 6). We consider the relevant areas to be any areas where the ground surface on either side of the tendon gallery (either Unit 1 or Unit 2) was near foundation level at the time of high subsurface water levels.
In addition, tnc proposed grouting of a small area at the southwest corner of Unit 1 tendon gallery must be more clearly explained since it appears that the grouting will fill the 5 inch seismic gap. Thus, we approve the licensee proceeding with item 5(Unit No. 2-Containment Area) as proposed. We require work on items 4 and 6 (Unit No. 1 - Containment area - inside and outside tendon galleries, respectively) to proceed in accordance with the procedures established for item 5, except that we require additional explanation of proposed grouting between Unit 1 ana the auxiliary building.
Item 8 requests release of all parts of the Turbine Building for continued construction. We have not required the submittal of detailed analyses of the erosion damage caused to and under the Turbine Building mud mat. Howc/er, during our site visit we noted erosion gulleys extending more than 4 ft. under mud mats and unusual cracking patterns, including openings as much a s 1 inch in the Turbine building nud mat. This building is not seis"lic Category I but we need a commitment from the licensee to make ev&luations and repai s in the Turbine building under the direction of the geotechnical engineer using the general procedures adopted for the seismic Category I foundations.
Furthermore release of this itemis contingent upon confirmation from the licensee that beneath tne Turbine Building there are no safety-related appurtenances such as pipes, cond. tits etc which are required for safe shutdawn of the plant.
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, ggt],,3g Item 9, Resumption of Concrete Work, can continue in proper sequence, as specified by the licensee, after repairs are made with respect to soils and foundations. Concrete work can resume after release by che geotechnical engineer.
Additional Information fleeded In attachment 1 to the licensee's submittal dated January 8, 1980, at page 1-14 the rtatenent is made that minimum set-back distances for structures at the tw of temporary stopes will be ar.alyzed on an individual case tasis. We require such analyses to be made for any safety-related structures located closer to the slope than that defined by an imaginary 2:1 (horizor.tal:
vertical) slope. The analyses should be documented and available at the site for our inspection.
The licensee is required to document all aspects of f1CR's and their resolution. We also request that the licensee document the repair ooerations by photographs.
E g ary L.e ;oncur in the licensee's request to resume the items of work outlined in the January 7, 1980 enclosure te his Jar.uary 8, 1980 submittal certi1;cr:t upon thc following conditions:
All relevant soils and dr,.;atering work will be performed under the
.ir.t 2 :n o' a o nlif La y te:nr.ical c ;irmer.
lis:hrgE f. om t a t. ell-; cint cy: ten ';ill be rar.:t n ir.r s i1 cc itcnt and pumping will be suspended if the soil centent excceds 5 parts per nillion.
3.
The e s t y ive wpr nch to t he c.1h: t < c.,
.' m. i xti;.7 of a- :2 around Unit 2 tendon gallery foundations will also be applied to Unit 1 tendon gallery foundations at all locations '..here the existing grade is near founcation elevation.
. 4.
Grouting procedures will be more clearly explained to shcw that the required 5 inch seismic gap between Unit 1 tendon gallery and the auxiliary building will not be compromised.
5.
Evaluation and re.cair of damaged mud mats in the turbine building will follow the general procedures for other dainaged mud mats.
6.
The licensee will verify that there are no safety related appurtenances under the Turbine building mud nat.
7.
The licensee will analyze safe set-back distances on terporary slopes for buildinjs located closer to the slooe than that forned by an inacinary 2:1 (horizontal vertical) slope.
8.
The licensee will provide photographic docurentation of repair operations.