ML19347A578
| ML19347A578 | |
| Person / Time | |
|---|---|
| Site: | Midland |
| Issue date: | 02/03/1969 |
| From: | COMMERCE, DEPT. OF |
| To: | |
| Shared Package | |
| ML19347A577 | List: |
| References | |
| NUDOCS 8007290995 | |
| Download: ML19347A578 (3) | |
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Comments on Midland Plant Units 1 and 2 Consumers Power Company Preliminary Safety Analysis Report Volunes I and II dated October 30, 1968 Prepared by Air Resources Environmental Laboratory Environmental Science Services Administration February 3, 1969 The location of the site in the east central part of Michigan in flat terrain where elevations range between 600 ar.J 625 feet above mean sea level, would indicate that atmospheric flow ic iargely governed by the large-scale, continental pressure patterns. Thus, in winter and spring when frequent storm tracks pass through the area, the ventilation rate would be high and atmospheric diffusion relatively good. From the Climatic atlas of the United States [1] this region of Michigan shows an average annual wind speed of about 11 mph, with a maximum of 13 mph in March and a miaimum of 8 mph in August.
The immediate approach to the plant from the south, west, and east is over rural, often marsh-like terrain uninterrupted by large buildings. Tne approach from the north includes the surface roughness and heat source effects of the city of Midland and the Dow Chemical romplex. However, this effect would be largely dissipated by the time tbe flow reached the southern site boundary. An on-site measurement of pertinent meteorological parameters such as the standard deviation of the horizontal wind (03) and the wind speed (Q) would inherently include the distant upwind turbulent effects provided the effect of the reactor building complex wake could be avoided.
The only near on-site wind data available is a 5-year record from two Dow Chemical wind stations about 1-1/2 miles to the northwest and the Saginaw Tri-City Airport climatological record about 8 miles to the s outheast. The Dow station shows an average annual wind speed of. 6.8 mph while the Saginaw station shows a value of 10.3 mph. The frequency of winds of 3 mph or less (incloding ccims) is 147. for Dow and 87. for Saginaw.
It is difficult to axplain the rather low wind speeds at Dow, especially since the data were taken atop a 60-ft telephone pole whereas the Saginaw data were taken at a height of 20 feet. The Caginaw data more nearly agree with the climatological wind data for.the region.
The cverage monthly gustiness data for Dow (Table 2A-11) 1,'dicates that in September 1966 the atmospheric diffusion rate was lesc than Pasquill Type E at a speed of 2 m/s for about 50% of the time during the sunrise hours.
- Since no joint frequency distribution data between gustiness and wind speed are given, it is not possible to quantitatively asses the probability of specific diffusion rates.
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Beside the reservations the applicant has with regard to the use of the Dow data (see p. 2A-32), we have the following reasons for questioning the validity of the Dow data in assessing the atmospheric diffusion from
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_1) wind speeds which seem un-Ed a ground source at the Midland nuclear site:the climatological averages of the region, usually low when compared to che ' difficulty in being able to classify "gustiness" by the range of 2)azimuth wind direction under low wind speeds (10% calm or i mph during September 1966 and 1967), and 3) since a ground source is postulated, the Dew wind data at a 60-f t height above the ground may not be appropriate.
The basis for the applicant's 2-hour diffusion model is the method by which routine hourly weather data (Saginaw) is used to obtain Pasquill diffusion categories. - Nine months of data were chosen on the basis of being the Each hour
" worst" diffusion months as judged by the Dow "gustinesa" data.
of the' 270 days of Saginaw data were then categorized. 2 to Pasquill Type 2
It should be pointed out that this method is an and wind speed.
approximate one which is used when more precise categorization, as with og,
The method, by definition, limits Pasquill Types E and F is not possible.
to nighttime hours and conversely limits Types A, B and C to daytime hours.
The applicant selected from each of the 270 days the " worst" consecutive two-hour pe*iod and then averaged the data over the whole sample to produce Thus, the first hour of the period contained the statistics for the model.
219, 32, and 19 hours2.199074e-4 days <br />0.00528 hours <br />3.141534e-5 weeks <br />7.2295e-6 months <br /> respectively for categories F, E, and D and the second The average wind speed hour contained 192, 46, and 32 hours3.703704e-4 days <br />0.00889 hours <br />5.291005e-5 weeks <br />1.2176e-5 months <br />, respectively.
for all the F cases was about 2 m/s.
In summary, since the Saginaw data shows that over a period of nine non-consecutive, " worst", months the frequency of moderate to strong inversions existed about 20% of the time at a speed of 2 m/s, it would seem (Type F) reasonably conservative to assume for the 2-hour' postulated release of The radioactivity, a diffusion rate equivalent to Type F and 1 m/sec.
resulting relative concontration at a distance of 1170 m would be 5 x 10 4 see m-3 as compared to the applicant's value of 1.75 x 10 '.
Reference
[1] U. S. Dept. of Commerce (ESSA), " Climatic Atlas of the United S*.ces",
June 1968, 80 pp.
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DATE RECEIVED NO.8 a e 9
Feb 7, 1969 Feb 10, 1969 FROMt aufi
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(Milton Shaw) onia.:
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To, Dr. Peter A. Morris 1
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ACTION NECESSARY O
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COMMENT BY:
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' REFERMED TO DATE RECElVED BY CATE DE.SQtlPTIONI ( Mvst Se Uncistsded j Memo tranemittings P. Howe 2-10 w/2 cye for ACTIC5 EHcusuaEr> dtd 2-3-69, ColeENIS/ PREPARED BY ESSA ON MIDLAND lafo Copias tc e PLANI, Units 1 and 2, Consumers Power H. Prike & 5 taff Co., PSAR Vols 1 and 2 (2 cys rec'd)
Morris /se" -d er Mason /treland (Palisades only Orig &.
Causetts, dtd 2-3-69, prepared by RSSA 1 ew=)
on Palisades Plant FSAR. Vols I, II &
31ust/;es11er (Midland only; Oritt &
1 cva) 111 (2 cys rec'd)
Royd Levine Skovholt aEmaaai
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