ML19347E567
| ML19347E567 | |
| Person / Time | |
|---|---|
| Site: | Braidwood  |
| Issue date: | 05/07/1981 |
| From: | Tedesco R Office of Nuclear Reactor Regulation |
| To: | Abel J COMMONWEALTH EDISON CO. |
| References | |
| NUDOCS 8105130010 | |
| Download: ML19347E567 (6) | |
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NUCLEAR REGULATORY COMMissiCN 1,lq7$j' l-f p
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Ducket Nos. STN 50-456 and STN 50-457 1Y Pn s.
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Mr. J. S. Abel
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Dear Mr. Abel:
SUBJECT:
QUESTIONS ON THE BRAIDWOOD OL APPLICATION In the process of our continuing review of the Braidwood Nuclear Power Plant, Unit Nos.1 and 2, for an operating license, we have identified the need for additional information concerning foundation engineering. This request from the Geotechnical Engineering Section is contained in Enclosure 1, Q362.1 to Q362.9. Note that these questions are for the Braidwood site; separate questions for the Byron site will soon be sent. Therefore please identify your responses to these questions as being for Braidwood only.
Sincerely,
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l'h'4 W d t-D Robert L. Tedesco, Assistant Director for Licensing Division of Licensing
Enclosure:
As stated cc w/ encl. :
See next page
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8185120014:
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'tr. J. S. Acel Director of Nuclear Licensing Common ealth Edison Company Post Office Box 767 Chicago, Illinois 60690 ccs:
Mr. William Kortier Mr. Edward R. Crass Atomic Power Distribution Nuclear Safeguards and Licensing Division
'4estinghouse Electric Corporation Sargent & Lundy Engineers P. O. Box 355 55 East Monroe Street Pittsburgh, Pennsylvania 15230 Chicago, Illinois 60603 Faul M. Murphy, Esq.
Nuclear Regulatory Commission, Region !!!
Isnam, Lincuin & Beale Cffice of Inspection and Enforcement One First National Plaza 799 Roosevelt Road 42nd Floor Glen Ellyn, Illinois 60137 Chicago, Illinois 60603 Myron Cherry, Esq.
Mrs. Phillip B. Johnson Cherry, Flynn and Kanter 1907 Stratford Lane 1 IBM Plaza Suite 4501 Rockford, Illinois 61107 Chicago, Illinois 60611 Ms. Julianne Mahler Center for Goverr. mental Studies Northern Illinois University DeKalb, Illinois 60115 C. Allen Bock, Esq.
P. O. Box 342 Urbanan, Illinois 61820 Thomas -J. Gordon, Esq.
Waaler, Evans & Gordon 2503 S. Neil Champaign, Illinois 61820 Ms. Bridget Little Rorem Appleseed Coordinator 117 North Linden Street Essex, Illinois 60935 Kenneth F. Levin, Esq.
Beatty, Levin, Holland, Basofin-& Sarsany 11 South LaSalle Street Suite 2200 Chicago, Illinois 60603
Braidwo;d Nuclear PJwer Plant Docket Nos. 50-456/457 First Round Questiens - Geotechnical Engineering 362.1
. Submit, time-se.ttlement' pibts for all Category I structures where 2.5.4.10.1.1 (RSP) settlements 'are being monitored. The plots should be up-to-date.
Tabulate values of me:sured maximum differential settlements and anticipated differential settlements assumed in the analysis of these structures and appurtenances such as connecting pipes and conduits.
Evaluate the impact of any differences between the neasured and the anticipated settlements on the design and construction of these facilities. Unless the applicant can demonstrate that adequate settlement margins are presently available and the+. future settlement will be negligible, the staff will require that the total and differential settlement of the safety related structures be monitored for a period of 5 years after issuance of the Operating License. The impact of observed settlement, if any, on the design limits of Category I structures and appurtenances should be evaluated annually during this period and reported to the NRC.
For the test data presented in Table 2.5-35 and 2.5-36, identify the and 2.5-36 source or location of the test specimens.
Section 2.5.4.3 of the FSAR indicates that the foundation excavation 362 (2. 6.34.3) was geologically mapped at 29 sections, whereas the sketches of only 3 sections are presented in the FSAR. Submit the detailed sketches of the remaining sections. The documentation related to the presence of coarse grained material (coarse sand, fine gravel, and cobble) in the bottom portion of the Equality fonnation (fine sand stratum) is l
of concern because of its impact on the seepage from the Essential Services Cooling Pond.
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362.4 The coefficient of permeability, K, parameter of the fine sand (2.5.6.6) stratum was determined by laboratory 'te'sts on reconstituted specimens. These tests do not simulate the in-situ flow condition as in'the casi of a field pumping test. Why didn't you perform field permeability tests?
Geologic Section 23 (Figure 2.5-50) and many borings drilled within the limits of the project (presented in FSAR section 2.5.4) reveal the presence of coarse grained material in the bottom 2 feet to 4 feet porticn of the fine sand stratum. The gradation of the sand is from fine to coarse size; fine gravel and cobbles are also present. The cutface in the strip mining area, in the imediate vicinity of the project, revealed the presence of relativ31y more pertneable material e7d showed marks to suspect that water is seeping in the bottom 2 to 4 feet zone of the fine sand stratum.
It is feasible that the rater frcm the Essential Services Cooling Pond (ESCP) may seep down to the more permeable zone beneath and travel horizontally. Does your seepage analysis cover this case?
If so, submit the details of your analysis.
If not, justify the rationality of your assumption that this seepage path does not exist and present your plan to confirm that this seepage path will not be operable.
362.5 In your analysis tne critical condition for maximum seepage from (2.5.6.6.3) the ESCP assumes that the icvel of water in the pond.s at elevation 590.0 feet and the level of water outside the pond is at elevation 580.0 feet. However, the lowest water level recorded in piezometer l
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LW-2, close to ESCP, is at elevation 577.5 feet (Figure 2.4-45). Using this as the' level of water outside ESCP, the differential head causing seepage is 12.5 feet rather than the 10.0 feet used in your analysis. What is the rationale for using 10 feet differential head in your seepage analysis?
Rd.o Ultimate Heat Sink - Essential Services Cooling Pond (ESCP)
(Sect. 2.4, 2.5, and9.2)
Clarify the inconsistencies in your statements (listed below) on the computed drawdown in ESCP due to evaporation and seepage.
Page 2.4-17: Drawdown,in ESCP due to both seepage and evaporation is 2 feet (178.5 acre feet volume).
Page 2.5-10: Drawdown in ESCP is 2 feet due to evaporation and 0.5 foot due to seepage.
Page 9.2-35: Drawdown in ESCP is 1 f oot due to evaporation and 0.5 foot due to seepage.
362.7 What is the value of the coefficient of lateral earth pressure 2.S.4.10.1.3 at-rest used in your design for the compacted backfill around the structures? Describe any conservatism involved in your earth pressure computations. Provide plots of earth pressure v/s depth used to design subsurface walls of various Category I structures.
362.8 Discuss the static stability of Essential Services Water Discharge Section 2.5.4.10 st ucture (Category I). Furnish drawings and detailed information to enable an independent review.
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