ML20244A779
| ML20244A779 | |
| Person / Time | |
|---|---|
| Site: | Crane  |
| Issue date: | 08/25/1972 |
| From: | Harold Denton US ATOMIC ENERGY COMMISSION (AEC) |
| To: | Muller D US ATOMIC ENERGY COMMISSION (AEC) |
| References | |
| NUDOCS 7911150504 | |
| Download: ML20244A779 (4) | |
Text
_ _ _.
1 AUG 2 5 BR D.
R.
Muller, Assistant Director for Environmental Projects HYDROLOGIC ENGINEERING COMMENTS ON EPA LTR OF AUGUST 16, 1972 PLANT NAME:
Three Mile Island, Units 1 & 2 LICENSING STAGE:
OL DOCKET NUMBERS:
S N 320 RESPONSIBLE BRANCH:
PWR 13 REQUESTED COMPLETION DATE:
N/A APPLICANTS RESPONSE DATE NECESSARY FOR NEXT ACTION PLANNED ON PROJECT:
N/A DESCRIPTION OF RESPONSE:
N/A REVIEW STATUS:
N/A Enclosed are hydrologic engineering comments on the dis-cussion of floods contained in the August 16, 1972, EPA m.,, _
lett'er to DR'on the subject" plant for your'us'e'in
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preparing the final environmental statement.
.ca dz J :. 3caba /
Harold R.
Denton, Assistant Director for Site Safety Directorate of Licensing
Enclosure:
As stated cc:
w/o enclosure DISTRIBUTION:
A.
Ciambusso
' Docket File 50-289 & 320 W.
Mcdonald L:Rdg.
L:SAB cc:
w/ enclosure L:AD/SS S.
3.
Hanauer J.
Hendrie J.
Youngblood R.
Regan H.
Faulkner L.
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THREE MILE ISLAND FLOODS UNITS 1 & 2 D0C. NOS. 50 - 289 6 320 HYDROLOGIC ENGINEERING COMMENTS (Response based on Comment on P.7 of Aug. 16, EPA Ltr to Muntzing)
The plant is to be protected from floods in excess of those with flow rates of up to 1,100,000 cfs by an extensive levee system around the northern part of the island.
The northern or upstream portion of the levec was completed prior to the flood, but had not been completed on the downstream or southern portion of the island.
The June 1972 flood, as a result of the presence of only a partial Es45E4 levee around the plant, flooded the westerly portion of the plant construction area around the four cooling towers by backing in through downstream uncompleted 1cvee areas.
For floods greater than the levee design flood up to the PMF (1,645,000 cfs), the plant is designed to be shut down, waterproofed, and the levee is designed to allow water to back into the plant area from the downstream southern end of the island.
The PMF (probable maximum flood) is based on the maximization of numerous hydro-meteorological parameters, of which storm precipitation and its time and space distribution are only a few.
Comparison of the Agnes precipitation with similar data used in the PMF determination indicates no need for modification of extreme precipitation estimates and, j
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therefore, no need to modify PMF runoff estimates accordingly.
Preliminary high water data from the June 1972 flood in the site vicinity have been reviewed to determine the adequacy of coefficients used to determine both the levee design water surf ace profile, and the PMF water surface used to assure that water will back into the plant area (rather than overtop the levee upstream).
In both cases, it is concluded that conservative l
coefficients have been selected and the flood design bMWON bases for the plant are conservative.
For instance, the Agnes water level at the intake structure was approximately elevation 300.0 ft. MSL, while the computed level is about elevation 302 ft. MSL.
During FSAR review of the plant the adequacy of riprap protection for the levee, and general maintenance of flood protection, was reviewed extensively.
Inspection L
i of the levee after the June 1972 flood indicated that although the riprap in place at the time appeared generally adequate, periodic maintenance of both the rock and the earth levee should indeed be undertaken at the intervals proposed by the applicant (annually and after every major flood).
It was noted that j
removal of riprap fines by floods, and extensive
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. vegetative growth in the levee as now exists, could reduce flood control effectiveness.
The hypothetical PMF is considered the upper limit of potential flooding at a particular site.
The staff does not consider larger floods credible and, therefore, does not require the design of nuclear facilities for more severe events.
It is concluded that the flood design bases for Three Mile Island have been conservatively estimated as a ENb@h result of a review of the record June 1972 floods on the Susquehanna River.
Through the August 16 EPA letter, the staff only first became aware of the proposed pump storage facility on Stony Creek.
We are reviewing the potential impact facility of the proposed
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on Three Mile Island and will require increased plant flood protection if any safety implications can be identified.
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