ML19256E653
| ML19256E653 | |
| 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 7911130541 | |
| Download: ML19256E653 (4) | |
Text
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AUG 2 51972 D.
R.
Muller, Assistant Director for Environmental Projects EYDROLOGIC ENGINEERING COMMENTS ON EPA LTR OF AUGUST 16, 1972 PLANT NAME:
Three Mile Island, Units 1& 2 LICENSING STAGE:
OL 5@f 3 320 DOCIET NUMBERS:
PWR RESPONSIBLE BRANCH:
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 hydrologie engineering comments on the dis-cussion of floods contained in the August 16, 1972, EPA letter to DR on the s ubj e c t plant for your use in preparing the final environmental statement.
- ,.+. :.d s' r.ed bz iL R. Dentoaf Harold R.
Denton, Assistant Director for Site Safety Directorate of Licensing
Enclosure:
As stated cc:
w/o enclosure DISTRIBUTION:
A.
Giambusso d ocket File 50-289 & 320 W. Mcdonald L:Rdg.
L:SA3 cc:
w/ enclosure L:AD/SS S.
'd. Hanauer J.
Hendrie J.
Youngblood R.
Regan 3.
Paulkner 1
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8/23/72 I
1%rtn A EC-318 (Rev. 9-53)
U.S. GOVERNuENT PWumMG OmCI dse,-o-24 5ge
THREE MILE ISLAND FLOODS UNITS 1 & 2 DOC. 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 levee 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 levee around the plant, flooded the westerly portion of the plant construction area around the four cooling towers by backing in through downstream uncompleted levee 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 downstrea=
southern end of the island.
The PMF (p rob ab le maximum flood) is based on the maximization of numerous hydro-me teorologi:a1 parameters, of which storm precipiration 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, 1647 346
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 coefficients have been selected and the flood design 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 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 maj or flood).
It was noted that lhk[ 34[
removal of riprap fines by floods, and extensive
m 3-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 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
/
on Three Mile Island and will require increased plant flood protection if any safety implications can be identified.
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