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'i DEPARTMENT OF THE ARMY COASTAL ENGINEERING RESEARCH CENTER KINGMAN BUILDING 50-361 FORT DELVOIR. VIRGINI A 22060 50-362 CEREN-DE 2 2 JUN 1973 1
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Mr. R. C. DeYoung Assistant Director for Pressurized Water Reactors
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Division of Reactor Licensing g.
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Dear Mr. DeYoung:
Reference is made to your letter of 16 June 1970 regarding Docket Nos, j
50-361 and 50-362; the Preliminary Safety Analysis Report and subsequent Amendments 1 through 18 thereto for the San Onofre Nuclear Generating Station, Units 2 and 3, of the Southern California Edison and San Diego j
Gas and Electric Companies.
In accordance with our arrangement, an engineer on the CERC staff has I
i reviewed pertinent information in the (PSAR) report leading to the esta-blishment of the maximum and minimum design water levels at the plant site.
It is his opinion, and I concur therewith, that a Probable Maximum water level elevation of 15.6 feet (MLLW) exclusive of the effects of wind j
i generated waves, as proposed by the applicant for a locally generated 1
tsunami, is sufficiently conservative.
This water level, elevation at
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15.6 feet, is composed of a tide component of 7 feet, storm surge component of 1 foot and a tsunami runup component of 7.6 feet.
The Probable Mini-mum low water level elevation of -11.3 feet MLLW is considered appropriate for design conditions.
It is also appropriate to include with the components that comprise the maximum design water level, the effects of either locally generated waves (sea) or distantly generated waves (swell) riding on the tsunami. A storm producing the one-foot storm surge could generate storm waves of height and period sufficient to break on the proposed steel sheet pile seawall fronting the plant site.
Based on available site information, an analysis was made of maximum waves expected to break and runup on the Q -Q'7 Q'L A 0b0 I 70 8710200008 871014 PDR FOIA pop SCHARAe7-462 n,
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Mr.-R. C. DeYoung vertical seawall at various stages of a fluctuating water level induced by the tsunami.
It was found.that when the water level exceeded eleva-1 tion 12.5 feet (MLLW), waves would begin to overtop the seawall at 30 l
feet (MLLW) top elevation thereby creating a flooding potential for the plant site.
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The selection of final design wave conditions to be used for determining the extent of wave overtopping and structure stability will have to await 3
the applicants' selection of the type, quality and configuration of the i
stone protection fronting the seawall.
i Sincerely yours, s..,;,y j,r
@ hb'LW [ M J ES L. TRAYERS
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[tommanderandDirector olonel, Corps of Engineers
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Mr. L. G. Hulman, AEC DAEN-CWZ-R/Maj Smith
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