ML20082P837

Testimony of J Purvis Re Meteorology of Region

ML20082P837
Person / Time
Site:	Catawba
Issue date:	12/02/1983
From:	Purvis J CAROLINA ENVIRONMENTAL STUDY GROUP
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ML20082P830	List: ML20082P826 ML20082P837 ML20082P844
References
NUDOCS 8312090201
Download: ML20082P837 (7)

Text

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UNITED STATES OF AMERICA  !

NUCLEAR REGTTLATORY COMMISSION BEFORE THE ATOMIC SAFETY AND LICENSING BOARD i l

In the Matter of )

)

DUKE POWER COMEANY, et. al. ) Docket Nos. 50-413

) 50-414 (Catawba Nuclear Station, )

Units 1 and 2) )

. . - a .

DIRECT TESTIMONY OF JOHN PURVIS ON BEHALF OF CESG Please state your name and business address.

John Purvis, Department of Natural Resources, State of South Carolina, 3803 Forest Drive, Columbia, South Carolina.

What is your position?

I am State C11matologist.

Do you have experience as a meteorologist? '

Yes. I was director of inversion studies for the United States Weather Bureau in Columbia, South Carol na.

Are you acquainted with the meteorology of this region?

4 .

Yes. ,

How would you characterize it?

In the context of the relationship of the Catawba nuclear station j to the City of Charlotte: The Catawba plant is precisely 17.6 miles

directly southwest from the intersection of Trade and Tryon Streets,

! the center of the business section of Charlotte. The closest approach to the plant is a distance of 9 7 miles from the city limit in the 22 sector to the northeast of the plant... The prevailing winds are generally from a southwesterly direction. There is an unusually high incidence of atmospheric inversions. There is also more than average rainfall in Charlotte.

What is the incidence of winds from Catawba over the City of Charlotte?

. 8312090201 831202 i PDR ADOCK 05000413 0 PDR

The data are somewhat limited but they are fairly consistent.

Based on observation made by Duke at the plant ' site at an elevation (

of 30 feet, June 30, 1971 to June 30, 197M wind from SW has a t probability of occurrence of 20 7%, from WSW of 8.7% and SSW of 5.6%. }

These winds carry over Charlotte. The total probability is 35.0%. [

If the wind blew at random, the probability would be 18.8%. This is f significantly directional. It is confirmed by data rpported by i Duke for the period 1976-1977 From the data in Table ER 2 3 0-2 at 40m above ground the corresponding occurrences are: SW 13 5%,

WSW 5 9~5 and and SSW 16.3% for a total of 35.7%. At 10m above j ground, about 33 feet, the occurrences are: SW 13 5%, WSW 7 1% and .

SSW 13.8% for a total of 34 4%. These occurrences are compatible f with and should relate to Charlotte weather Bureau records. The a records for the period 1941-1970 show a prevailing wind direction f from the SW at a mean speed of 7.5 miles per hour. For 8 months of i the year the prevailing wind direction was either from the SW or

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from the SSW. In 1982, under the National Oceanic and Atmospheric

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Administration a different system was used for reporting wind k direction. Direction was reported in 10 increments. SSW would i correspond to 191.25 to 213 75 from north; SW to 213 25 to 236.25 ;  :

and WSW to 236.25 to 258 75 from north. The range of these three -

directions is very nearly from 190 to 260 In 1982 for five months  !

the prevailing wind direction fell within this sector. Result, ant [

speeds for these months ranged from 0.5 miles per hour in March to ir 2 4 miles per hour in July. The maximum wind speeds during these _

months was 20 miles per hour. This indicates a pattern of directional' changes, including reversals. The probability of a plume released  ;

at the Catawba plant being carried over Charlotte is about twice [

that of random chance. The wind speeds are such that the probable -

minimum time for a release to reach the city limit would be half an hour. As the mean wind speed is 7 5 miles per hour it would on the average take an hour and twenty minutes to reach the city j limit, about two hours to reach city center. Under some circumstances -

a change in wind direction could carry the plume back over the path by which it arrived.

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i How frequent are calms in this region?

The Environmental Report indicates a 4 3% incidence of calms in -

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the period 1969-1973 and of 9.6% in 1976-1977 0bservations made in 1976-1977 report an 8 77% occurrenes o'f winds between 1.0 and 3 3 miles per hour at 40m; of 25.68% at 10d. To the extent that a plume deposits particulates, relatively still air results in a higher ground concentration of particulates. The length of exposure to radioactive gases in the plume would be increased, and the dilution by mixing of both gases and suspended particulates would be slowed.

Calms are also the cause of' inversions.

What are inversions?

Under normally windy conditions there is good mixing both horizontally and vertically of the atmosphere. As the temperature of the upper atmosphere is lower than that of the earth's surface, a negative temperature gradient results. That is, the higher above the earth's surface, the lower the temperature. Under conditions of low air flow the atmosphere near the surface is appreciably warmed. When, through heat loss by radiation, the earth cools more ,

rapidly than the air above it, a positive temperature g.radient results. The intersection of the lower positive gradient air with the higher negative gradient air is a barrier to the mixing of the lower air with the upper air. Warm air will, due to density differ-ences rise in a negative gradient, decline in a positive gradient.

Attachment A shows the behavior of plumes under six gradient ponditions.

By retarding vertical mixing, inversions further contribute to the maintenance of high concentrations in pollutant releases, exacerbating the problem of poor mixing and slow transport which I earlier referred l to.

Are inversions frequent in the Catawba / Charlotte vicinity?

They are among the highest known in the United States. The thirty year weather record shows that this locality experiences on the average more than 350 inversions a year.. In contrast, Chicago is in the 50 a year zone. Inversions there were notorious because the amount of soot in the atmosphere was high enough to cause black days.

A radioactive plume staying close to habitations will cause more l exposure than one rising and mixing upward.

Whnt effect does rainfall have on a plume?

-h-Rain washes particulates out of the atmosphere and brings them to earth. Under dry conditions the particulates in a plume are t

brought down by gravity. Larger, denser particulates settle more f

rapidly than smaller, less dense particulates. We are all familiar l

with the conveyance of pollen and dust by the wind. ,

l What do we know about the nature of the particulates in the release from a nuclear accident?

Very little. Assumptions are made about the particle size distribution. One can conceive of the particulates in an accident l j

release differing with the nature of the ' accident. But of one thing we can be sure. In dry weather small particles will be borne

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farther from the release than large particles. If rain is encountered I both large and small particles will be brought down at a distance j nearer to the point of release than would otherwise have occurred and at a higher concentration because there will have been less 1

l opportunity for mixing.

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i What is the incidence of rainfall in the Charlotte area? 4 On the average there have been 112 days with recordable rain in Charlotte. In 1982 there were 120 days. This is one day in three.

How much rain falls in Charlotte?

• 3 The thirty year average is 42 72 inches water equivalent. This includes snow and ice pellets. In 1982 the total precipitation was 41.69 inches. -

How does this compare to other parts of the country?

There is a listing of weather data from 29 weather" stations of the rainfall in typical meteorological years in NUREG/CR'-2239. The average of these values is 29.9 inches. Charlotte receives 43%

more rain than the average station reported.

How heavy or light is this rainfall? .

It covers the range from mists or drizzle to heavy. In a 30 year period the heaviest 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> fall was 5.34 inches. In 1982 the heaviest fall was 2.17 inches in 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />. A h6avy enough rainfall will tend to wash away pollutants. The average Charlotte rainfall is 0 38 inches, hardly a cleansing downpour.

6 f.

Are there any other weather factors in relation to an atmospheric I release of radioactivity that you would call to our attention?  ;

Yes. Snow would probably entrain particulates with about the b same efficiency as rain. The larger surface to mass ratio of snow j flakes would make them more efficient scavengers than spherical drops. @

There are strong attractive forces between small particles and larger [

masses; the snow would not need to have a moist surface to capture  !

aerosol dimension particles. The particles would be immobilized f l where the snow fell. Depending on the rate of the thaw, there could j be little or no runoff and efficient deposition of the particles 5 on the ground and other snowed-on surfaces.

f Is this the only effect snow would have?

Not necessarily. Dpending on the rate of fall, depth, wetness, [:

etc., it could seriously impede automobile travel--in this context, a

i evacuation.. Other severe weather conditions could interfere with a communication by siren or bullhorn such as high.. winds and the noise background that would be generated. 1 2

Does this complete your testimony in regard to weather influences j E

in the ovent of an ac'cidental release of radioactivity into the atmosphere? 3 a

Yes.  :

A 5

How would you sum up your testimony? , i The prevailing winds are such that Charlotte has twice a random h chance of.having a release from the Catawba plant come over it. Low [ .

wind speeds and frequent inversions would make for prolonged exposure [

1 in the event of such a release. The probability of ra'inout of [

particulates over Charlotte is about 40% more than for average reported national weather conditions. Insofar ne meteorological conditions 5 affect the consequences of an accidental release of radioactivity,

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Charlotte is substantially more at risk than a representative community of the same size at the same distance from a nuclear plant.

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, Attcchm2nt A t 4 * .=

POLLUTANT CONCENTRATION VARIATION D. B. Turner *

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THE INFLUENCE OF VERTICAL TEMPER- elevation of the plume is encountered.

ATURE STRUCTURE UPON STACK EFFLU- -

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ENTS -

Clear skies with light winds during the_ . i

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night are favorable conditions for fanning.

1. ' The' manner in which stack effluents diffuse. - " ' ' '

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is primarily a function of the stability of. LOFTING the atmosphere. Church (1949) has typed  ;

the behavior of smoke plumes into five classes. j Hewson (1960) has added a sixth class taking Lofting occurs when there is a superadia-  ;

into account inversions aloft. batic layer above a surface inversion. *

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Under this condition diffusion is rapid up-

--" ward but downward diffusion does not LOOPING

_~ out. With these conditions gases will not Looping occurs with a superadiabatic lapse reach the surface but particles with rate. Large thermal eddies are developed appreciable settling velocities will drop in the unstable air and high concentrations through the inversion. Near sunset on a 3 may be brought to the ground for short time clear evening in open country is most favor-

able for lofting. Lofting is generally a

] intervals. Diffusion is good however when considering longer time periods. The transition situation and as the inversion [+

superadiabatic conditions causing looping . deepens 'is replaced by fanning. ~

occurs only with light winds and strong solar

" heating. ';1oudiness or high winds will 'I FUMIGATION prevent such unstable conditions from forming.

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y As solar heating increases the lower layers N

, CONING are h~tted and a super-adiabatic lapse rate - I occurs through a deeper and deeper layer.' I With vertical temperature gradient between When the layer is deep enough to reach the fanning plume, thermal turbulence will j

dry adiabatic and isothermal, slight instability bring high concentrations to the ground 1

occurs with both horizontal and vertical along the fulliength of the plume. This mixing but not as intense as in the looping i<

situation. The plume tends to be cone shaped is favored by clear skies and light winds and i ,

hence the name. The plume reaches the is apt to' occur more frequently in summer I"

due to increased heating.

ground at greater distances than with looping. '

Coning is prevalent on cloudy or windy days or nights. Diffusion equations are more Another type of fumigation may occurlin the successfulin calculating concentrations for early evening over cities. Heat sources i

this type of plume than for any other, and mechanical turbulence due to surfa'ce L '

roughness causes a lapse condition in the

) 19 wer layers of the stable air moving into L FANNING the city from non-urban areas where radiation inversions are already forming, 9 If the temperature increases upward the air is This causes a fumigation until the city loses i stable and vertical turbulence is suppressed, enough heat so that the lapse condition can no longer be maintained.

Horizontal mixing is not as great as in coning 'I L but still occurs. The plume will therefore '

} 2 y spread horizontally but little if any vertically.  ; n TRAPPING l j

J Since the winds are usually light the plume .

- will also meander in the horizontal. Plume When an inversion occurs aloft such as a

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concentrations are high but little effluent from

. I, elevated sources reaches the ground with this frontal or subsidence inversion a plume

.I situation except when the inversion is broken released beneath the inversion will be trapped..'.D, j l 1 due to surface heating, or terrain at the beneath it. Even if the diffusion is good , ..._.. _ ;

beneath the inversion such as a coning plume, 1j Meteorologist, Air Resources Cincinnati '

Laboratory ESSA, NAPCA, Cincinnati, Ohio 1 PA. ME. sd. 30a. 8. 62 24 li S

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d Pellutant Conenntr*ti*n V*riati*n 1

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( the limit to upward diffusion willincrease g

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4 concentration in the plume and at ground l tevei. ..._ 3 i

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The six plume classes are diagrammed in E y the accompanying figure.

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2 ss Q J S

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Diurnal Variations of Ground-Level Concen

,, trations from Elevated Urban Sources i- ... ..

m 1 The prin,ary maximum around 10 AM is  !

Q due to fumigation. The rapid decrease in j Ij j >._,' g3, . _ .,..L tonea*

concentration following this is due to the heating of a progressively deeper layer -

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and mixing of pollutants through this layer. .

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'" " Tile increase of concentrations during the g ',* late afternoon are due to the slight increase j in stability after the period of maximum , j j heating. During this period the lapse

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$ rate is generally changing from strong 1 6 ,3r/, "'..

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, lapse to weak lapse. l y; - ............... .'

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\ "' *wr **= nas The secondary maximum that occurs in i

the evening is a phenomena observed only r N

• VARIATIGN OF POLLUTANT COCENTRA- in the urban area. During the late afternoon (

TIONS DUE TO METEOROLOGIC VARIATIONS and early evening a radiation invez sion. "

begins to form at the earth's surfage in the '

'.j An example of the diurnal variation of non-urban areas, i.e., the surrounding '

pollutant concentrations is given in this countryside. The air over the city,'how-j{

figu r e. These are the concentrations ever, does not have a radiation inversion some distance down-wind f rom a contin- in the lower layers due to release of heat .

uous elevated urban source on a day when from the buildings and pavings of the city.

stability reaches extremes, i. e. , on a. However, later in the evening, an inversion clear day with light winds. This shows. above the weak lapse layer forms above the l:.. .

only the variations on the order of an city and a mixing of the pollutants in this hour's duration rather that the rapid varia- layer produces the higher concentrations.

tions which may occur a few minutes .

This has been described by Munn and Katz g duration. . .

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