ML20040H488
| ML20040H488 | |
| Person / Time | |
|---|---|
| Site: | Dresden, Quad Cities, 05000000 |
| Issue date: | 05/31/1980 |
| From: | Mcdonald J TEXAS TECH UNIV., LUBBOCK, TX |
| To: | NRC OFFICE OF NUCLEAR REGULATORY RESEARCH (RES) |
| Shared Package | |
| ML20040H481 | List: |
| References | |
| NUDOCS 8202180303 | |
| Download: ML20040H488 (29) | |
Text
- - _. _ _ _ _ - - _ _ _ _ _ _
3 1
~ ~ ~ ~
~ ~ ~ ~
l TORNADO AND STRAIGHT WIND HAZARD PROBABILITY
~
s--
.- ~ _
e--
~
~ ~ ~ ~ - =
'- ' ' ~
DRESDEN NUCLEAR POWER REACTOR SITE, ILLINOIS by James R. Mcdonald, P.E.
N'"
ee e.
eg
- e
,,p p em -
k W
.e A
2 8202180303 820210 PDR ADOCK 05000254 PDR G
TORNADO AND STRAIGHT WIND HAZARD PROBABILITY for DRESDEN NUCLEAR POWER REACTOR SITE, ILLIN0IS-by.
James R. Mcdonald, P.E.
}
I k
4 Prepared for U.S. Nuclear Regulatory Commission Site Safety Research Branen Division of Reactor Safety Research May,- 1980 1
i Institute for Disaster Research-i Texas Tech University.
Lubbock, Texas 4
l l
l L
FOREWORD Hazard probability assessment for tornadoes and other extreme winds -
' at the Dresden nuclear power. reactor site are presented herein at the request of Robert F. Abbey, Jr., Site Safety Research Branch, Division-of Reactor Safety Research, U.S. Nuclear Regulatory Commission. The work is supported under NRC Contract NRC-04-76-345.. Principal Investi-gator and Project Manager for_ the Institute for Dissster Research is James.R. Mcdonald, P.E.
4 l
t I
l i
e l-e a
a
I.
INTRODUCTION The objective of this report is to assess tornado and straight wind probability hazards at the Dresden nuclear power reactor site (See Figure 1). The hazard probability analyses are developed using storm records from the geographical region surrounding the site.
Ninety-five percent confidence limits on the probabilities are presented to give an indication of the accuracy of the expected hazard probabilities.
The final hazard probability model is presented graphically in Figure 6.
Windspeeds corresponding to selected probability values are summarized in Table 8.
The basic data used in the calculations are presented in this report.
Derivation of the tornado hazard assessment methodology, the rationale and assumptions are given in Mcdonald (1980)..
Use of the Type I extreme value distribution function for straight wind hazard assessment is well documented in Simiu and Scanlan (197,8).
i O
9 e
1
8 u*
- i:iN!:: i:W:!!i;j:j!ji
!!;li;fj!i'
- .tl:l:fll m*m GLCGAL sk:!!!
'diii REG;cN i
- i j:::!:
s ii:t
!!!$lij w'.SC:7dSN s
._._,i l
R.L1NOS s
i:i i:!:
t!!M:M
!!l {!
i i:i:h:!: :!.l:i p ---
m est a i
O l
l I
I I
4-j PEORIA LOCAL REGION l
l
.I I.
FOANA 040 l
1
.e
<[% ^.
g.
/
FIGURE 1.
LOCAL AND GLOBAL REGIONS FOR DRESDEN l
f l
2
II.
TORNADO HAZARD PROBABILITY ASSESSMENT A.
METHODOLOGY The tornado hazard model developed by the Institute for Disaster Research (IDR) accounts for gradations of damage across the tornado path width and along its length (Mcdonald,1980).
There are four basic steps involved in the methodology:
(1) Determination of an area-intensity relationship in a global region surrounding the site of interest.
(2) Determination of an occurrence-intensity relationship in a local region surrounding the site.
(3) Calculation of the probabilities of a point within the local region experiencing windspeeds in some windspeed interval.
(4) Determination of the probability of windspeeds in the local region exceeding the intervil values.
B.
CALCULATIONS 1.
Site Dresden Nuclear Power Generating Station 2.
Coordinates Latitude 41 23' 23" N Longitude 88 16' 17" W 3.
Area-Intensity Relationshio Global Region s
Latitude 39 to 44 N Longitude 84 to 90 W Data DAPPLE Tornado Data Tape UT1678 (Fujita, et al.,1979)
Period of Record 1971 - 1978 i
3
See Figure 1 for definition of the global region.
The region is selected to be as large as possible and still give reasonably homoge-nous conditions for tornado formation.
The relatively short period of record is used because the data are more comolete and accurate than that collected prior to 1971, especially with regard to tornado damage path characteristics.
The area-intensity matrix is shown in Table 1.
It gives the number of tornadoes in each corresponding area-intensity classification.
From this information, the mean damage path area per F-scale can be obtained.
TABLE 1 AREA-INTENSITY MATRIX Number of Tornadoes
- Area Mean Area Interval F0 F1 F2 F3 F4 F5 (so mi) 0 91 28 6\\
0 0
0 0.316E-02 17, N NO 0
0 0.100E-01 1
32 51 2
16 61 19 4\\
0 0
0.316E-01 N
3 12 33 31 6
N0 0
0.100E-00
\\
0 0.316E-00 4
6 28 17 5
0 0 \\ 11 0.100E 01 15 2
1 g
5 6
0
\\2 7
8 6
1 0.316E 01 s
0 4
4 0
0.100E 02 7
0 0
8 0
0 N0 1
1 0
0.316E 02 9
0 0
0 N 0
2 0
0.100E 03 10 0
0 0
\\0 0
0 0.316E 03 Totals 157 214 112 30 14 1
- Those tornadoes outside the dashed lines are considered outliers and have been eliminated from the data set.
Mean Damage Path Area Per F-Scale F0 F1 F2 F3 F4 F5 Mean Area,.
sq mi 0.0268 0.1495 0.4141 3.3729 20.826 3.160 Median Windspeed, mph 56 92.5 135 182 233.5 289.5 4
9 Area-Intensity Function Linear regression analysis of the above area-intensity data, based on a log-log plot, yields the following functional relationship:
Log (Area)=3.744LogV-8.173 (1)
The coefficient of determination is 2 = 0.974 r
Area-Intensity Relationship The expected mean area is obtained from Equation (1) above.
Upper and lower bound confidence limits are calculated at the 95 percent level. These values are shown in Table 2.
Figure 2 shows a plot of the area-intensity relationship.
TABLE 2 AREA-INTENSITY RELATIONSHIP WITH 95 PERCENT CONFIDENCE LIMITS F0 F1 F2 F3 F4
' F5 6
Expected Mean area, a, sq mi
.0236
.1546
.6367 1.9486 4.9535 11.0788 j
Lower Limit a,
g sq mi
.0119
.0783
.3221
.9846 2.4990 5.5789 Upper limit a$,
sq mi
.047
.305 1.258 3.856 9.819 22.001 Median F-scale Windspeed, mph 56 92.5 135 182 233.5 289.5 4.
Occurrence-Intensity Relationship Local-Region Latitude 40 to 42 0
Longitude 87 to 90 Area = 21,645 - 650 20,995 sq mi
=
An area of 650 sq mi is deducted from the local region because of Lake Michigan.
There are, of course, no tornadoes recorded over water.
See Figure 1 for definition of local region and its relation-l ship to the site.
5
10 0
/
a
/
2 to
/f's'/
d,
/
u g
/ 0
/
()
/
/
b
/l,'
5'
/
,/
/
' )/
7
/
/
~
/
/
/
l
~
o.1
\\
/
/
m
/
O
/
95% CONFIDENCE f
f
{
/
/
INTERVAL O
/
l 0.01 56 925 13 3.5 18 2 233.5 289.5 3,
x s.j l
WINDSPEED MPH s
l FIGURE 2.
AREA-INTENSITY RELATIONSHIP FOR DRESDEN l
e 6
Data DAPPLE Tornado Data Tape UT1678 (Fujita, et al.,1979)
Period of Record 1950 to 1978 The records used do not necessarily include every tornado that has occurred in the local region.
For one reason or another, some tornadoes go unreported. Because the population density of the local region is high (greater than 800 persons per square mile) and because the terrain is such that identifiable paths can be seen should a tornado touch down (damage to structures, trees, fences, or power lines), the number of unreported tornadoes in the region is likely.to be less than five percent. The number of reported tornadoes in the local region is shown in Table 3.
TABLE 3 1
NUMBER OF TORNAD0ES'IN THE LOCAL REGION a
F0 F1 F2 F3 F4 F5 s
Number of Tornadoes 86 122 79 24 7
0
' Cumulative Number 318 232 1,10 31 7
0 s
LowerBound;F-Scale Windspeed, mph 40 73 113 158 207 261 Occurrence-Intensity Function The function used is obtained by performing a linear regression analysis using the FO and F1 tornadoes an,d another linear regression analysis using the F2 to F5 tornadoes.
Linear regression analysis of the data in Table 3 on a semi-log plot gives the following functio;'al relationships:
~
-0. 00415x y = (466.02)l0 (x < 96 mph)
-0.01273x (2) y = (3077.02)l0 (x > 96 mph)
N whe,re y is the cumulative number of tornadoes with windspeeds greater
\\
than or equal to x.
k
'l..
7
J 4
(r, 0ccurrence-Intensity Relationship
?
,t
//
'MThe expected number of tornadoes in the 29 year period is obtained i
f, rom the occurrence-intensity function (Equation 2).
Upper and lower F[ Lqund confidence limits are also obtained at the 95 percent level.
. These values are then divided by the period of record (29 years) to obtain the number of tornadoes per year for each F-scale classifica-tion Aj, which is the needed occurrence-intensity relationship required a
g
' for the hazard probability assessment.
Table 4 lists the values u:ed in the probability calculation.
Figure 3 shows a plot of the occurrence-intensity relationship.
}
TABLE 4 OCCURREf1CE-IflTEllSITY RELATI0tiSHIP WITH 95 PERCErlT C0t1FIDEtlCE LIMITS
/
1
)"
F0 F1 F2 F3 F4 F5 j,
t L Expected number of
\\
tornadoes in inter-val, n 86.00 119.99 82.07 22.82 5.66 1.46 f
Lower limit 6 70.48 103.05 66.78 13.80 1.04
,,4 Upr.er limit 6 101.53 136.93 97.36 31.84 10.28 3.83 Expected number of tornadoes per year A 2.97 4.14 2.83 0.79 0.20 0.05 1
Lower limit A 2.43 3.55 2.30 0.48 0.04 Upper limit A 3.50 4.72 3.36 1.10 0.35 0.13 l
4, 5.
Tornado Hazard Probability f
The tornado hazard probability calculations are performed by computer, although they can easily be'done by hand.
The expected l
[
hazard probabilities are obtained by using the expected area-intensity relationship (aj) and the expected occurrence-intensity relationship (Aj).
Upper and lower limits of hazard probability are obtained by using the upper and lower limit Aj's and aj's respectively.
The
\\
computer printouts for these calculations are contained in Aopendix A.
l Table 5 summarizes the tornado hazard probabilities, and includes
- 4 the 95 percent confidence limits. The tornado hazard probability
', ~
model is plotted in Figure 4.
Final hazard probability results are c'
summarized in Section IV of this report.
u h
l l 'Q 14 8
I
ll1ll zO. Oi FOgZ4OOWm 5s 5EOOLWWOg LC n
y0WO L gW8 OS
_ 0W 1
9 a
1 0
0 0
o, i0 0
0 10 0
0 0
0 s
F I
G 9'v%
2 F
U
. O R
5 E
0 3
- F l
PO EC W
1 RC CU ER I
0
.s NR N
0 TE D
N F
N CC S
OE P
N E
s s
N-FI IN E
DT D
1 g
N EE 5
NN 0
\\
\\
3F Cs EI
\\
s T
9 LY
\\
M I E P
N I
MR TL H
2 3
SA 0
T 0
N
\\
. F I
4 O
\\
s N
N SH N
\\
I P
2 N
W 5 Nh 5
0 I
F TH 9
N 5
N 30 x 0
350 l
llll
TABLE 5 TORNADO HAZARD PROBABILITIES WITH 95 PERCENT CONFIDENCE LIMITS Mean Hazard Tornado Windspeeds, mph Recurrence Probability Expected Lower Upper Interval Per Year Value Limit Limit 10,000 1.0 x 10~4 102 56 162
-5 100,000 1.0 x 10 195 138 242
-6 1,000,000 1.0 x 10 261 200 321
-7 10,000,000 1.0 x 10 337 259 417 m
b t
e 9
M' O
O e
e 10
9
-3 o
g r io s
h W
N l
E N
h N
N l
-4 I x 10 Z$
\\
OW N
,W>
N
\\
W N
g
-5 Z
l x 10 o
N
\\
'o N
\\
z
\\
N
(
\\
\\,
Fo
-6
\\
i Jw ixto s
g Eg
\\
N
< v>
\\
8e N
5
-7
\\
1xlo so 10 0 iso zoo 250 soo 350 WINDSPEED MPH FIGURE 4.
TORNADO HAZARD PROBABILITY MODEL WITH 95 PERCENT CONFIDENCE LIMITS t
11
III.
STRAIGHT WIND HAZARD ASSESSMENT A.
METHODOLOGY A set of annual extreme fastest-mile windspeeds are used to fit a cumulative probability distribution function in order to obtain the straight wind hazard probabilities.
The Type I extreme value function generally fits the data well.
In view of the studies by Simiu and
.Filliben (1975), the Type I distribution function is used in lieu of the Type II that was used previously (ANSI,1972). A detailed description of
^
the methodology is given in Simiu and Scanlan (1978).
B.
CALCULATIONS Annual extreme fastest-mile windspeed data are not available at the power reactor site.
Although the closest weather station with the needed data is Midway Airport (located approximately 40 mi northwest of the site),
it is felt that the data at Peoria, Illinois (located 83 mi southwest of the site) is a better representative for wind conditions at the site.
The data are taken from Simiu, Changery and Filliben (1979) and covers the 35-year period 1943 to 1977.
Statistical tests performed by Simiu (1979) indicate that the Type I extreme value distribution does not fit the Peoria data quite as well as some other locations within the United States (the tail length parameter y is 350 rather than infinity as required for a true Type I distribution).
However, because the Type II distribution predicts windspeed values at' low probability levels that exceed the physical characteristics of the wind, the Type I distribution function is recommended 'for straight wind hazard probability assessment at this site.
The Type I distribution as found in Simiu, Changery and Filliben (1979) for Peoria is used for the straight wind model at the Dresden reactor site.
12
The set of annual extreme fastest-mile windspeeds for Peoria, Illinois are given in Table 6, along with the date and direction.
The windspeeds have been adjusted to a standard anemometer height of 10 m.
The straight wind hazard probabilities for various mean recurrence intervals, along with 95 percent confidence limits, are shown in Table 7.
The same data are plotted in Figure 5.
TABLE 6 ANNUAL EXTREME FASTEST-MILE WINDSPEEDS AT PEORIA, ILLIN0IS Windspeed Year mph Direction Date 1943 63 NW 07/28 1944 52 E
04/11 1945 52 SW 11/08 1946 52 W
06/12 1947 69 SW 04/05 1948 54 SW 12/05 1949 49 W
01/ 27 1950 57 SW 05/05 1951 47 W
09/26 1952 47 SW 11/26 1953 70 NW 07/05 1954 51 SW 05/31 1955 47 NW 03/22 1956 61 W
08/13 1957 49 SW 03/14 1958 56 SW 10/09 1959 56 W
09/26 1960 51 NW 05/24 1961 47 SW 03/27 1962 44 W
04/30 1963 45 NW 07/19 1964-61 W
11/20 1965 56 W
09/14 1966 44 NW 03/31 1967 50 NW 02/23 1968 43 NW 12/04 1969 47 W
06/25 1970 48 NE 05/13 1971 50 SW 12/15 1972 -
41 W
01/24 1973 59 NW 06/16 1974 54 W
07/14 1975 55 W
07/23 1976 47 W
03/04 1977 48 SW 03/30 13
TABLE 7 STRAIGHT WIND HAZARD PROBABILITIES WITH 95 PERCENT CONFIDENCE LIMITS Mean Expected Upper Lower Recurrence Hazard Fastest-Mile Limit Limit Interval Probability Windspeed, moh mph mph 10 1.0 x 10-I 62 67 57 20 5.0 x 10-2 66 72 60
-2 50 2.0 x 10 71 79 63 100 1.0 x 10-2 75 84 66
~
200 5.0 x 10-3 79 90 69
-3 500 2.0 x 10 84 96 72 1,000 1.0 x 10-3 88 102 75 10,000 1.0 x id'4 102 119 84 100,000 1.0 x 10-5 115 137 93
-6 1,000,000 1.0 x 10 128 154 102 e
0 4
e S
6 14
I O
.J h
Ix10
\\
g 0
\\
\\
=
I
\\
\\
F-
\\
-2 lx10
\\
\\
e e
!5
\\
\\
W>
\\
\\
-3
\\
(-
1x10 O
\\
\\
u*5
\\
\\
\\
Fo
-4
\\
\\
g g
\\
\\
E
\\
CL.
t 4 to
\\
E Q
\\
\\.
-5 i
lx10 50 10 0 15 0 200 250 300 350 l
WINDSPEED MPH I
FIGURE 5.
STRAIGHT WIND HAZARD PROBABILITIES WITH 95 i
PERCENT CONFIDENCE LIMITS l
e 15
IV. WINDSPEED HAZARD PROBABILITY MODEL Windspeed hazard probability, which includes both tornadoes and straight winds, is the probability of a point within some defined geographical region experiencing windspeeds greater than or equal to some threshold value in one year. Tornado hazard probabilities are thc-same at any point within j
J the defined local region.
The Type I extreme value distribution function obtained from data collected at Peoria, Illinois is used for the straight wind probability hazard assessment at the Dresden reactor site.
- Thus, in effect, Peoria and the reactor site are contained in a common local region.
Tornado windspeeds are referenced to 30 ft above ground level (approx-imately 10 m) and are the maximum horizontal windspeeds. According to Fujita (1971), F-scale windspeeds are fastest-one-quarter mile winds.
l However, because of the translational speed of a tornado, winds acting on a structure may be of considerably shorter duration.
Because tornado '
windspeeds are based on appearance of damage, they are considered to be effective velocities, which include effects of gust, structure size and structure frequency.
For design purposes, the gust response factor for tornado winds may be taken as unity.
The straight winds are fastest-mile windspeeds which have a variable time duration, depending on the magnitude of the windspeeds.
Values are normalized to a 10 m anemometer height.
For design purposes, gust response factors greater than unity are appropriate (See ANSI A58.1,1972).
The tornado and straight wind models are combined in Figure 6 to obtain the final windspeed mddel.
For design or evaluation purpose,s, one needs to know the type of storm that controls the criteria.
For windspeeds less than 102 mph, the straight wind model governs.
For windspeeds greater than 16
102 mph, the tornado model governs.
In the case of a tornado, the atmospheric pressure change and missiles must be taken into account in addition to the wind effects.
Because of this, the union of the two events (tornado and straight winds) is not of particular interest. Table 8 sumarizes the final windspeed hazard probabilities.
9 1
9 4
e 17
-_ ---_ _ _.-.-_ _ ~.
-I l x lO q
\\
\\
\\
\\
\\
"'2
\\
\\
O d
\\
\\
4 Tag?"r
\\ I E
\\
\\
\\
F l x io-3
-\\ \\
\\
~
e EE
\\\\(k
\\
\\
w
_4 l x io i
gg
$5
(
s 1
N
\\
E h
\\
O
-5 i x 10 N-bO TORNADTSb
\\-
g
__ w s
k
\\
,x io
\\
\\ \\
-e 13 95 PERCENT
\\
\\
CONFlDENCE
\\
k LIMITS
\\
-7 l x lO 50 10 0 LSO 200 250 300 350 WINDSPEED MPH FIGURE 6.
TORNADO AND STRAIGHT WIND HAZARD PROBABILITY MODEL FOR THE DRESDEN POWER REACTOR SITE, ILLIN0IS e
18
TABLE 8
SUMMARY
OF WINDSPEED HAZARD PROBABILITIES FOR DRESDEN Mean Expected Recurrence Hazard Windspeed Interval Probability mph Type of Stonn
-l 10 1.0 x 10 62 Straight Winds
-2 100 1.0 x 10 75 Straight Wind
-3 1,000 1.0 x 10 88 Straight Wind
-4 10,000 1.0 x 10 102 Straight Wind or Tornado
-5 100,000 1.0 x 10 195 Tornado
-6 1,000,000 1.0 x 10 261 Tornado
-7 10,000,000 1.0 x 10 337 Tornado 4
4 k
O O
9 6
4 19
REFERENCES 1.
ANSI, 1972:
" Building Code Requirements for Minimum Design Loads in Buildings and Other Structures," A58.1, American National Standards Institute, Inc., iiew York, New York.
2.
Fujita, T.
T., 1971:
" Proposed Characterization of Tornadoes and Hurricanes by Area and Intensity," SMRP No. 91, The University of Chicago, Chicago, Illinois.
3.
Fujita, T. T., Tecson, J. J, and Abbey, R. F.,1979:
" Statistics of U. S. Tornadoes Based on the DAPPLE Tornado Tape," lith Conference on Severe Local Storms, Kansas City, Missouri, October 2-5, 1979, published by American Meteorological Society, Boston, Massachusetts.
4.
Mcdonald, J. R.,1980:
"A Methodology for Tornado Hazard Assessment "
Institute for Disaster Research, Texas Tech University, Lubbock, Texas.
5.
Simiu, E., Changery, M. J. and Filliben, J. J.,1979:
" Extreme Wind-speeds at 129 Stations in the Contiguous United States," NBS Building Science Service 118, National Bureau of Standards, Washington, D.C.
6.
Simiu, E. and Scanlan, R. H.,1978: Wind Effects on Structures, John Wiley and Sons, New York, New York.
7.
Simiu, E. and Filliben, J.
J., 1975:
" Statistical Analysis of Extreme Winds," Technical Note No. 868, National Bureau of Standards, Washington, D. C.
8.
U. S. Nuclear Regulatory Commission,1979:
Demographic Statistics Pertaining to Nuclear Power Reactor Sites, NUREG-0348, Office of Nuclear Reactor Regulation, Washington, D. C.
e e
O e
1 e
9 20
e.
L. ~
.1-
~
x.. w..,.,..
_. v.s.
~-. _..
.*C
~
L L Uk 7
- r.:. ~- - :.
-.~.,
~~..
e
...%. =.
-v
. O-
,L.3 r-w e C. A, S. er o
~
-a O...
~.
O O O ~.-
- ~-
e
~ m :-..-
2..
4/)
H 3O n.
~.,~.
e
,,,u C.
. r, M
w Cd
" C v,. ' '. C
. ~~..
c.
w g
S.
LAJ l--
3 Q.
d C. C.C.av,C.N C 0 0.,0 *- *
."s O
c v
y L
O. C....
C
~
n.
CC~e
+
- w
., +.
C" t.
m O
,~..
n n
..,., L.
na..... -...
4.tJ
..e c+,
.. e
~,
e -
, w, D.
e.,.......
Q.
C C O C C. O O ~ O O O '-
e Ot.,
e:C
~.
s A
g.
e.,,.
..e.
s, e.3
. C f.,...-
.......s
-.. n. <
.~. m
.e e,, cn c e.
ww -.
.e. n ~.
m
. s
- s. n,
.~..
e n
. a.
P.
~. ;.
~
O O
.r.
4 w
.C
~
w
~ ~_ *-
O C..' '. ~ *
~
a.
C.
~
~. * > <
n e,,,.
. ~. r..e. e. _
.m- *e,,,
=-
C, L es s.
......s. v
.m.
O
~;
4 OCCCC0 C "/ O ; O C
- "4 *. ;
~. ~ ~.
f 4
C,,
e.
.L
.~
..O '. N, ~.
e.
.. - e.
., ~.<.. r.
c.
..o e.3
~
~
y ~
g
- - ~
Oe-~OO me-e.
%.=
.n he e
a-f.
m g,
g 21
g___
Q e
s
-. _. - n
, ~.,,.,N..a
, f 6
... r.,..
s.-
aa
._.. ~
e
. r s.
~m.. -.
s.
% n c c.
,.. s..
d.
- w e
. s V
%.. ~ c.
a.
w.- 6 e
.n.
~-,.,. -
~. C -
- a. O.
s.-
.+ n-.
- e. - w.
w w e -,
n.
~
n.
e n., -.
v..w.n-
- n.. n, a., CC a
w.,.
www n.~,
n
. w r
I e.
- e.,.
e.,. C, - ~. c, e.,,..
+.......
w w
O,.. w,.
i w
C.. e..
C..n.....,. ~..
- s. s C.
m
. m C w.
~
e.
e.
e e w
s s.
b 4
e.
- .w p' ~.
e.
y.
e.
.,.r.e.
w
. e
,.~ +.
w,..,..
_s n.
r.
. r.
w
....s.
C.,.,.
L-,w e.
- v..-
w w w
..s
.e c.
N e
.s..
e.
O_~
~. ~. <
e,.
,a.. n.
- s....
. e.
e,..e s
s.
- r. s, a.
. e..o'.
.~
.~.. n w C w.
e-w e
e e...
a N
m t
- 4.. <
e
.s.c.
f,
=
.,. r4 e _ s a.
C.
e.,..
. =-
s.r.
.... e
. w
- s. v-a O
e.
w C e,.-
n w w-w
. f.
e n
e-e
~ =
v.
s.
D.-
r.
w
-a 9-c.
r~
~,,,
O. e C. * <.
~
C. *'.2?
.~
..,.s 3..,..
._.c s. s....
...3 e.e.
e.
n s
s.
-g
's'.'.
C..<.".
O 1
e.
.. c.
w
.. C,.
~
.e e.
.s e
h.
4.#
.h e.
,e w
e,p.
e.
p.
e.-
w W
b.,
-M h
s 4
b 96 22
9 1
o i:...,i.,
,o.n..
i..,
.Ii i.
i,
- l...Iii..
..i.
, s is l' L ' I L s *s-he t s,0 it.
,hr i't
- I l's. e 'l l i t l l ist il i i1:i's.l'as ;! l !. i.s I
- l. J al i i er a.+
1 '
6'.
h' 14 i*.
- 00
.l l y *.
4 8 i/ 1t 41 1 tehs li k
- t' I Mr - 1.*18 '
It '.. I l i s t i all it 'l l i.a *. ' I I.
It s alt).11
.:1 o,
. 't e r e t.1:1 4 ' Itt j tel
'J f. s; 8
- t*'!.
.i'*l.
- t ' i t,
'. L 's' ; =
f.L**l-
'.. L *.' l.
Li ) l l'
- i'.8 titli I s *l'is ti.
I"
'.**/
t /
- i t t i,
- 1 VL4*/
i.)c**'1 1
i l
- t so
(.t*O c ';'o'
- i 1<*f*I u s *b.
l
.t t
- O 14 0
'O
',*/ t 1
/t.*t t 4.
.'s.;
l 00-)
s.
- V-o
- )il l
- t i t O *.
.. '.,;*t Od #
- O g Oip
- s
- i.
( < s'
- l s'i/l*d i o';
- t (508)* O oJO*O O d ')
- u in eJ
- o f ;'.Y
- d C(0*d r
I s.OJ'o 000'O 000 0 pos
- o 0 0..
- O
.s bi' O 1
l h
M N
1 tr!;i ' O b l H '.S OutI* t)
% *k' k0' h
e
[I I I
- . V i,I i ' 4) bO g.
4 4 LI
$E
/f eo
- O
- 41. ' 'l
- O IW*
- O 1,' t
- d a Y.3*Q 11/.O
- I 9 t ;11
- C dOb'O 000*O L* / I
- O Olld'O i'it t
- 0
- A'O
/ C.P
- n ll' *4
- 1 000'O isOO O
('.00
- O 66d'O i.li O s' Y O
- I
. : :,
- L.
8.O'i ' O O id e.
000 0 OOu'O 000*O 8;'iv ' O oJL't 19';*t Jt o O
.hus
- O 000'O 000*O 0u9 0 OOO*O
- /is s I !!V f 1U
). l.'l l Vl4 '4 i Ill t !.:) I i h l i fallil!
l'i j.*l llH l:i.PDI i
i /./ /h /t i j
- l*It'1%4t ol:lli. l *. ti f'.
U1 O ').'t:Ju *l. f
'I'l l.'j ll.I' 'Wlu i til I t l.41... f. i')
e i
f.
4 y
MCDONALD. MEHTA AND MINOR CONSULTING CNGINEERS BOX 4543 TECH STATION LUBCOCK. TEXAS 79409 Js.M ES R. MCDONALD, P.E.
KIIHOR C. MENTA. P E.
JOTEPH E, MINOR, P.E.
1 February 5,1982 Mr. Rob Fitzgibbons Isham, Lincoln and Beale One First National Plaza Suite 4200 Chicago, IL 60603 RE: -Tornado Risks at the Quad Cities Nuclear Power Reactor Site
Dear Mr. Fitzgibbons:
The purpose of this letter is to address two questions which you raised in our telephone conversation of February 3,1982:
- 1) Are the results of the tornado risk analysis that I prepared for the Dresden nuclear reactor site valid for the Guad Cities site?
- 2) Does the topography at the Quad Cities site, i.e. the Mississippi River Valley, play a role in tornado risk that is not eflected in the risks calculated for the Dresden site, which is surrounded by relatively flat open country?
The Quad Cities sita is approximately 120 mi west of the Dresden site.
The attached Figure 1 gives the total number of reported tornadoes per one-degree square of latitude and longitude. The data are obtained fram the tornado data base assembled by Dr. Ted Fujita at the University of Chicago. The one-degree square surrounding the Quad Cities site experienced 55 tornadoes while the one surrounding the Dresden site recorded 59 tornadoes in the period 1950 - 1979.
The table below shows a breakdown of tornadoes by F-scale for the two sites.
Number of Tornadoes F-Scale Quad City Dresden F0 11 13 F1 24 23 F2 14 18 F3 5
5 F4 1
0 j
F5 0
0-TOTAL 55 59
Letter to Mr. Fitzgibbons February 5,1982 Page Two The number of tornadoes per one-degree square in Wisconsin, Iowa and Missouri is about 30-40 percent less than the number in degret squares in Illinois.
However, the degree square surroundine, the Quad Cities site appears to match best with the number of occurrences in Illinois. Thus, from the occurrences and intensity points of view the two sites appear to be very svailar.
Allen (1980) in an effort to regionalize tornado hazard probability identified a " Midwest" region in which tornadoes have a common area-intensity relationship.
The Quad Cities and Dresden sites are located in the approximate center of this region.
Thus, the two main ingredients in a tornado hazard probability assessment appear to be similar for the two sites. A site specific assessment of tornado risks at the Quad Cities site would produce results almost identical with those o' tained for the Dresden site.
a With regard to the effect of topography on tornado risks, damage documentation indicates that on the scale of a river valley, the effect may be undiscernible.
Tornadoes have been reported by Fujita that traveled over mountainous terrain from 1800 ft to 3000 ft elevation (Blue Ridge tornado of April 3,1974). The writer flew over more than two hundred miles of tornado path in northern Alabama following the April 3, 1974 outbreak. The paths went over hills and into tiie valleys (estimate 300-500 ft changes in elevation), sometimes lifting up but oftentimes producing continuous devastation. These paths crossed streams, rivers, ponds and lakes without interruption of the path.
The Brandenburg, Kentucky tornado (April 3,1974) passed through the city producing F5 damage, crossed the Ohio River and continued uninterrupted or.
the other side.
Numerous other examples of tornadoes crossing rivers and lakes can be cited.
Large topographic features such as mountain ranges can influence tornado formation.
They produce the so-called " shadow effect." The lack of tornado formation in these cases is because the topographic feature forms a barrier to moisture encroachment, which is needed for tornado formation. Two examples of the shadow effect are the Southern Rocky Mountains and the Appalachian Mountains. There are no barriers to moisture in the Quad Cities area.
Thus, in my opinion, topography at the Quad Cities site is not likely to affect tornado risks in a way that would make risks at Quad Cities substantially different from the Dresden site.
Letter to Mr. Fitzgibbons February 5,1982 P3ge Three I hope my responses to your questions have satisfactorily addressed the issues.
If there are questions I will be happy'to respond.
I can be reachedat(806)'742-3479.
Very'truly-yours, f
$^2-6t40MfnL.
e r
James.R. Mcdonald, Ph.D., P.E.
JRM:sas
/.
Attachment I
J