ML20209C088

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Forwards Analysis Re Potential for High Winds & Tornados in Response to 830223 Request.Probabilistic Analysis of High Winds,Including Tornado Winds,Performed to Place Design Basis Wind in Proper Perspective
ML20209C088
Person / Time
Site: Rancho Seco
Issue date: 03/09/1983
From: Gammill W
Office of Nuclear Reactor Regulation
To: Parr O
Office of Nuclear Reactor Regulation
References
TAC-48907, NUDOCS 8304130298
Download: ML20209C088 (3)


Text

{{#Wiki_filter:_ _ _ _ - _ - - 4 j '/- ' puerg e . joi UNITED STATES 8 '.. j NUCLEAR REGULATORY COMMISSION WASHINGTON, D. C. 20555 n4 - l \\..CJ... f" man b il G83 Docket No. 50-312 MEMORANDUM FOR: Olan D. Parr, Chief Auxiliary Systems Branch, OSI FROM: William P. Gammill, Chief Meteorology and Effluent Treatment Branch, DSI ~

SUBJECT:

POTENTIAL FOR HIGH WINDS AND TORNADOES AT RANCHO SECO (TA'C NO. 48907) The following analysis is provided in response to your request of February 23, 1983. The licensee-stated that all safety-related components are protected against non-tornado winds of up to 101 mph and the missiles that could be generated by such a wind. To placs..t.his design basis wind in proper perspective, we have performed a probabilistfc analysis of high winds including tornado winds for the Rancho Seco site. A probability distribution of high winds without tornadoes was taken from Simiu, et al, 1979 (" Extreme Wind Speeds of 129 Stations in the Contiguous United Stater," NBS Building Science Series 118). This distribution is based on an analysis of 29 years of fastest mile wind data from Sacramento, CA. For tornadoas, a probability distribution of tornado winds was calculated using the combined methodologies of WASH-1300 and of Thom, 1963 (" Tornado Probabilities," Mon. Wea. Rev., pp. 730-736). This distribution is based on 27 years of tornado 2 data within a 2x2 latitude-longitude " square" (area = 14,767 mi ) centered on yr-1 and the magnitude of a tornado at the 10-' yr-{ornado st Based on these data, the probability gf a the Rancho Spco site. probability is 4.7 x 10-0 level is 200 mph. The expected value probability distributions of non-tornado and tornado winds are shown in Figure 1 (enclosure). These distributions show that'the Rancho Seco non-tornado wind of 101 mph will recur, on the average, about every 1000 speedatthe10gtopimiu(1979),thestandarderrorofestimatingthewindprob years. Accordin yr-

e e i i ~ O. D. Parr M.AR 0 91333 This evaluation was performed by E. Markee, Meteorology Section. If you have any questions about this evaluation, please contact Mr. Markee at x27635. Original signed tr 3 Uinlan Y. M U.,, William P. Garanill. Chief !!cteorology and Effluent Treatment Branch Division of Systems Integration

Enclosure:

Figure 1 cc: R. Mattson D. Muller L. Rubenstein R. Capra R. Lobel E. Sylvester S. Miner I. Spickler E. liarkee DISTRIBUTION: Docket File 50-312 METB Docket File METB Reading File WPGammill 1

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