ML19341A449

Task 1 - Analytical Approach,Site-Specific Characteristics at AR Nuclear One

ML19341A449
Person / Time
Site:	Arkansas Nuclear
Issue date:	12/31/1980
From:	DAMES & MOORE
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ML19341A446	List: ML19341A445 ML19341A449
References
5195-051-09, 5195-51-9, NUDOCS 8101230539
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TASK 1 - ANALYTICAL APPROACH SITE-SPECIFIC CHARACTERISTICS AT ARKANSAS NUCLEAR ONE ARKANSAS POWER & LIGHT COMPANY 5195-051-09 31 DECEMBER 1980 LIf s

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December 31, 1980 Arkansas Power & Light Company Post Office Box 551 900 Center Street Little Rock, Arkansas 72201 Attention:

Mr. Allen Smith Re: Task 1 - Analytical Approach Site-Specific Characteristics At Arkansas Nuclear One Gentlemen:

The enclosed report presents the results of Task 1 as presented in our 6 October 1980 proposal entitled " Effects of New NRC Guidelines on the Arkansas Nuclear One Meteorological System".

This task was authorized in your letter of 8 December 1980 (Contract No. D-001G; Task No. 002 Q) and presents the anticipated analytical approach to be used in the assessment of the site-specific characteristics that must be considered in defining any meteorological monitoring program and in the determination of the method-ology to be used in assessing the transport and diffusion processes at Arkansas Nuclear One (AN0). As indicated in the proposal, these approaches should be reviewed by Arkansas Power & Light Company (AP&L) to ensure the investigation takes cognizance of information available to AP&L and their experiences at the ANO site.

It is also suggested that subsequent to inclu-sion of any additional information or modification based on AP&L's review, the approach be discussed with the Nuclear Regulatory Commission (NRC) to l

ensure that the planned efforts benefit from the information available to i

the NRC and to obtain concurrence with the study approach.

Upon completion of this review process and prior to the authorization of any subsequent task presented in the original proposal, we will prepare an updated cost estimate for your consideration based on the final configu-ration of the Task 1 Analytical Approach.

Dzmea & Moore f,},

eli Arkansas Power & Light Company r-December 31, 1980 Page 2 9

Please let us know if you have any questions concerning the enclosed report. We are looking forward to discussing the proposed approaches with you in order to establish a program that will meet both your and the NRC.

requirements.

Sincerely, DAMES & MOOR by )I +/L/

p Hubert B. Vis'scher Partner l

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j Stanley I. Rrivo Senior Peteorologist HBV:SJK:tjr Enclosure xt:

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g TABLE OF CONTENTS 1

i Page 1.0 ' INTRODUCTION AND

SUMMARY

1 2.0 COASTAL INTERNAL,, BOUNDARY LAYER STUDY................

5 4

2.1 GENERAL DESCRIPTION.............................

5 1

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2.2 ONSHORE AIR FL0W............

7 fi 2.2.1 Cold Water / Warm Land.....................

7 2'.2.2 Warm Water / Cold Land.....................

10 2.3 0FFSHORE AIR FL0W...............................

11 i

3.0 TERRAIN EFFECTS......................................

13 4.0 EFFECTS OF HEATED RESERV0lR..........................

15 5.0 EFFECTS OF WIND DIRECTION MEANDER....................

16 6.0 BUILDING AERODYNAMIC WAKE EFFECTS....................

17 APPENDIX..................................................

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1.0 INTRODUCTION

AND

SUMMARY

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sented in the proposal entitled " Effects of New NRC Guidelines on the This report documents the results of the Task 1 analysis as pr t-E Arkansas Nuclear One Meteorological System" (6 October 1980). The

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overall objective of the total investigation is to assist Arkansas Power & Light Company (AP&L) in defining the computer model and meteo-rological monitoring instrumentation needed to satisfy new Nuclear Reg-ulatory Commission (NRC) requirer.ents as applied to the Arkansas Nu-EE clear One (AN0) station.

The specific requirements under consideration are:

Proposed Revision 1 to Regulatory Guide 1.23, " Meteorological Programs in Support of Nuclear Power Plants".

-* Appendix 2, NUREG-0654, " Meteorological Criteria for Emergency Preparedness at Operating Nuclear Plants".

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NUREG CR-0936, "Recomnendations for Meteorological Measurement.

Programs and Atmospheric Diff'sion Prediction Methods for Use at u

Coastal Nuclear Reactor Sites".

These requirements include the eventual development of two site-spe-cific dispersion models, designated Model A and Model B.

Because the schedule for Mad B has 1982-83 as the time frame for development and because the gu'ieiines for this model are evolving, our investigation, although applicable to Model B, will be aimed at pro-ducing information adequate to the design of the meteorological moni-toring system and the development of the site-specific dispe'sion Model r

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A.

The specific objective of Task 1 is to develop the analytic ap-F proaches to be used in assessing tFe 4ffects of the site-specific fea-tures on the atmospheric tranrror ata dispersion characteristics.

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This obji.tive was accomplik y tnr gh the consideration of all pre-F=

vious infestigations of meteorclogical and dispersion conditions at the q

site, the review of data available for such an investigation, and through the review of the plant and topographic. features of the f acil-ity. ;;

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5 The site-specific characteristics that are considered to have a E"

potential effect on the dispersion and transport characteristics are ta 17 the presence of Lake Dardanelle, the use of the reservoir (Lake Dar-danelle) for heat dissipation, and the terrain features near the site, ige Because the meteorological data obtained from the present meteorologi-cal tower system will be used in assessing effluent dispersion and E-transport, the particular effect of these site-specific characteristics on the measured data are of concern.

Should the measured meteorologi-

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cal data prove affected by characteristics that are not applicable in the assessment of transport and dispersion for given condi.tions, for example, specific wind directions, time of day, etc., then this know-n' ledge will be used in the development of the Model A dispersion model and/or be used to recommend additional meteorological monitoring sta-tions to provide guidance or actual data for this assessment.

In addition to these site-specific considerations, the proper ap-plication of the meander phenomenon during low wind speeds and consid-

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eration of the wake feature will be ' accomplished.

Although the use of the available onsite data will not assist in this determin. tion, the frequency of appropriate conditions for the possible meander will aid 3,

in the evaluation of its significance.

It is expected that review of the plant configuration and review of the applicable literature on these subjects will enable the proper application of these additional site-specific factors in the evaluation of effluent transport and dis-persion.

Of particular interest as a reservoir effect is the possible de-velopment of a coastal internal boundary layer (CIBL), because this ef-fect, if it exists at the ANO site, could have considerable bearing on the atmospheric dispersion of radionuclide releases at ANO during CIBL periods.

The remaining sections of this report present the studies antici-u

r ifc pated for those items that are considered site-dependent and may affect the transport and dispersion conditions.

These sections present the following information:

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• Section 2.0 - Discussion of the CIBL phenomenon, and the analy-f tic techniques proposed to assess its significance at the ANO site.

This section includes detailed presentation of the an-

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ticipated techniques applicable to each of the existing mete-orological parameters measured at the onsite tower.

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techniques, although presented in the.CIBL analysis section,

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may be used in the investigation of other site features and, therefore, may be referreJ to in Sections 3.0, 4.0, and 5.0 of this report.

• Section 3.0 - Discussion of the approach proposed for the as-sessment of terrain effects on atmospheric dispersion of ef-fluents from the ANO sise.

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Section 4.0 - Techniques proposed to assess reservoir heat dis-sipation effects on atmospheric dispersion.

• Section 5.0 - Discussion of wind direction meander correction terms for use in the dispersion Model A.

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• Section 6.0 - Discussion of building aerodynamic wake effects r

for use in dispersion Model A.

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The approaches for the major site-specific characteristics of concern (Sections 2.0, 2.0, and 4.0) have as a goal the identification of any effect the site-specific chac acteris'.ics have on the meteorological parameters, the determination as to whether the meteorological monitor-ing system measures these effects, and the applicability and/or needed

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modification that should be considered in the use of these data for the assessment of dispersion and transport.

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A list of anticipated additional data required to perform the pro-posed study is presented in the Appendix. The precise periods for which detailed meteorological data will be needed can only be deter-mined during the course of the study.

'2 From the results of Task 3 of the proposal, the actual performance IS of the analyses presented herein or as amended following discussions between Dames & Moore and AP&L, site-specific information adequate to t

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address the new NRC requirements with respect to all the effects of y;

concern should be developed.

Because the proposed investigation will 5

be limited by the data available, the presence of a CIBL and definitive determination of other objectives may not be possible.

These available c

data have been acquired for other purposes, as the monitoring program was not designed.to detect the presence of a CIBL nor to detect other reservoir effects. Should the approaches presented herein not be ade-quate to determine the effects of the site-specific characteristics, or to characterize the meteorological conditions under which the effects of the CIBL, topography, and reservoir are not properly accounted for

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a in the present monitoring program, additional studies and/or monitoring programs may be required and presented as part of the conclusions reached in this investigation.

For example, an acoustic radar study at the site may prove necessary in order to assess the effects of possible CIBL formation on local dispersion conditions.

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2.0 C0ASTAL INTERNAL BOUNDARY LAYER STUDY

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2.1 GENERAL DESCRIPTION The development of a Coastal Internal Boundary Layer (CIBL) is a common occurrence at ocean coastal locations and on the shores of other large bodies of water. The land and water surf aces at the coastline generally have distinct roughness and thermal characteristics, and these craracteristics strongly affect the atmospheric turbulence of air flowing anove the two types of surface.

For air flow perpendicular to the shoreline, air having turbulence features due to one surf ace type may override air having features due to the other surf ace type. Thus, I

a relatively thin surface layer of air may be capped by air of very different characteristics, with a sharp boundary separating the two at-

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mospheric regimes. This is the situation referred to as a CIBL.

The presence of a CIBL can have profound effects on the dispersion of pollutants. For example, the most common type of CIBL consists of relatively cold stable air in an onshore flow overlying warmer, more turbulent air developed over the warmer land area.

In this situation, effluent plumes released above the CIBL boundary will have initially limited dispersion under stable conditions but, upon' encountering the boundary, become very quickly mixed to ground level in a process known as fumigation.

Effluents released below the boundary can remain trap-ped by the low-lying lid resulting in diminished dispersion.

In either case, the existence of the CIBL can result in higher ground-level con-centrations than would occur without the CIBL.

Lake Dardanelle at the Arkansas Nuclear One (AN0) site is much smaller than the bodies of water that are known to routinely produce

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CIBL's (for example, the oceans, the Great Lakes, and Tampa Bay).

How-ever, in principle the same mechanisms could possibly give rise to CIBL formation around the Lake Dardanelle shore. Therefore, the possible

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be considered in the development of the site-specific dispersion Model.

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5 The questions to be addressed in the proposed study are as fol-lows:

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Does a significant CIBL formation occur at the ANO site?

If so, what meteorological conditions are required for or condu-

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cive to CIBL formation?

2.

What are the particular characteristics of any CIBL formed at v:.

the ANO site?

3.

Are the onsite meteorological measurements affected by CIBL formation?

4.

How should a CIBL affect the assessment of dose for radionu-clide releases at the site, given the available meteorological data and the requirements for the dispersion Model A?

Because of the limited extent Ef Lake Dardanelle, land areas can be affected by radionuclide releases from ANO for both onshore and off-shore air flow.

Therefore, both of these conditions must be considered in assessing CIBL formation and any possible effects. Another factor strongly affecting the CIBL is the temperature difference between the land and water surfaces.

The anticipated approach involves separating

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these factors as presented in Sections 2.2 and ? 3.

An additional con-sideration, addressed in Section 4.0, is the ch.nge in the lake's sur-f ace temperature distribution due to heat dissipation from operation of ANO Unit 1.

This heat load could conceivably affect CIBL formation to such an extent that the MODEL A characterization should differ accord-ing to whether Unit 1 is operating or not.

The information resources available for the proposed study corsist primarily of onsite meteorological data, other ANO data such as histor-ical operating schedules and measured lake surf ace temperatures, and the existing literature of coastal effects on atmospheric dispersion, Bec'ause none of the onsite monitoring efforts to date have been design-m E

ed to detect or characterize CIBL formation, the proposed study may not result in a completely realistic or definitive resolution of this is-i sue.

In such case, the important features to be included in a monitor-ing program and in the dose assessment calculations (by dispersion

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Model A) will be determined from the application of applicable results 5

presented in the existing literature to the specific site features at E

Lake Dardanelle.

The conclusions reached by the proposed study may include a recom-m mended program whereby the importance of the particular features of the ANO site can be better ascertained and quantified.

The recommended program may include. additional meteorological monitoring and the use of special techniques such as acoustic sounding of the atmosphere to de-

.l tect possible CIBL formation.

2.2 ONSHORE AIR FLOW 2.2.1 Cold Water / Warm Land

. A flow onshore of colder, more stable air from above a colder wa-5 ter surface to the warmer land surface is the general seabreeze condi-tion.

This is generally the most important flow condition in terms of frequency of occurrence, likelihood of CIBL formation at the site, and effects of CIBL formation on the atmospheric dispersion features at the site. Under this condition, fumigation or limited mixing are possibil-ities.

The location of the meteorological tower and the topography of the site indicate that the tower will be exposed to onshore air flow for winds blowing from the directions between ENE and SSE, and primarily from due East.

In the other directions, significant fetches of land

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intervene between the tower and the reservoir.

However, it is noted that the directions from the tower for which winds would pass over no part of the reservoir are restricted to the sector between NW and N.

To ascertain the importance of the onshore, cold water / warm land flow at the ANO site, the meteorological data from the onsite tower and the available surface water temperature data will be analyzed as fol-lows:

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1.

Determine the months of the year during which the surf ace tem.

perature difference between land and water is largest. This g

determination +ill be separately performed for the reservoir heated by Unit 1 operation, and for the unheated reservoir.

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For the months found in step 1, select the hourly periods when

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onshore air flow occurred concurrently with a positive lard-b' water surf ace temperature difference greater than some minimum cut-off value. A reasonable minimum cut-off value will be de-g 5!

fined from the existing scientific literature on CIBL forma-

. tion.

3.

Using the selected data subset, perform the indicated analysis for each meteorological parameter:

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• Temperature difference - Determine the Pasquill stability class associated with each temperature difference (AT) mea-surement between the 10 m and 57 m levels of the tower.

Compare the resulting stability frequency distribution to the distribution for the total data period, to onshore flows not within this selected subset, and to offshore air flows for a similar period.

Should the subset stability frequency distribution exhibit uncharacteristic features, determine the AT characteristics of the anomalous hours and examine the ambient conditions that could explain the anomalies, if possible.

A comparison between the stability class calcu-lated from AT, and the stability class at each level, calcu-lated from the horizontal variance of the wind direction (ce), will be made for selected anomalous hours to see if differences exist that would be characteristic of a CIBL lying between the tower measurement levels.

(Becausece values are not automatically calculated for the upper tower level, these will be reduced by hand from strip chart re-cordings during the anomalous periods.)

• Ambient temperature / dewpoint temperature - Review these data concurrent with the selected AT data, to determine if the air shows characteristics indicative of recent overwater e

passage.

This will involve comparisons between the upper and lower dewpoint measurements, and between the frequency distributions for onshore and offshore flow.

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• Wind direction - The data selection indicated above will be based on the wind direction values measured at the 10-meter level of the tower.

Comparisons will be made between the upper and lower wind direction values to identify periods during which these differ by more than about 45 degrees.

The other meteorological data on the selected periods will then be studied along with synoptic charts to see if these

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periods should be eliminated from the data base because of particular, non-representative conditions, or to illuminate 5

or explain the reason for the vertical wind shear.

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• ce - The standard deviation of the horizontal wind di, rec-

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tion, c, is a valuable parameter to review because it pro-e vides a measure of stability at each measured level.

Unfor-tunately, a statistical comparison between the upper and lower tower levels is not practical because the upper level I

og is not operationally reduced to digital form.

It may prove of value to review the wind direction chart traces for selected periods of interest, in order to directly compare the ce figures at each level. The ce data for the lower level will be segregated into onshore and offshore flows, and the resulting frequency distributions compared.

The presence of reservoir-modified air at the tower would be in-P dicated if the onshore flow conditions consistently result valves.

in relatively smaller ce

• Synoptic weather conditions - The general synoptic condi-tions for the selected periods of interest will be reviewed,

.c in order to help explain unusual features, and to eliminate periods for which the criteria of interest were met not be-f:

cause of the effects of site-specific features, but rather because of synoptic conditions, t;:

f5 It was noted in the. AND Final Safety Analysis Report (FSAR) that winds blowing from the reservoir were ' associated with a higher frequen-cy of unstable atmospheric conditions (as determined from AT measure-ments) than were winds blowing overland. This observation will be

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2 examined in greater detail in the proposed study.

We note at this En time that this observation admits to two (and possibly more) interpre-A tations, namely:

1) that onshore flows do not result in restricted dispersion, or 2) that CIBL formation is common at the site, because _a y

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CIBL lying between the sensing levels on the tower could result in an unrepresentative " unstable" AT value.

2.2.2 Warm Water / Cold Land The situation in which the water surf ace is warmer than the land

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surface can also give rise to CIBL formation, altnough the nature of

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the CIBL formed in this case is somewhat different than in the cold water / warm land case. The stability of air above cold water is' en-

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hanced because both thermal and roughness contributions to turbulence are small. Above warm water, the thermal contribution to turbulence. is increased, but there remains little contribution to turbulence due to the mechanical effects of surface roughness.

In general, one expects that, given the same surf ace temoerature,. the stability of air above water is considerably greater than that of air above land, and experi-mental measurements bear out this expectation.

Thus, any CIBL formed in the warm water / cold land situation will, in general, require a larger difference in land-water surf ace temperature than is required

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for the cold water / warm land case, and also will usually be much less intense (that is, there will usually be a smaller difference in the stability of the air on either side of'the CIBL).

For onshore air flow, a warm water / cold land CIBL involves warmer, more turbulent air overlying a layer of colder, stable air at the land surface. This situation is conducive to dispersion of pollutants.

Plumes released into the upper turbulent layer will be maintained alof t g

above the boundary layer and will therefore not impinge on the ground.

'F Plumes released inside the lower stable layer will often not be affed-ed by the CIBL at all; if they do impinge on the CIBL, they will tend g

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from the ground.

One also expect that a CIBL of this type will quickly disappear with distance downwind.

The warm, moist air that is lifted above the

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9 colder stable land layer has been removed from its source of turbu-lent energy (that is, the warm water surface), and the resulting verti-cal density profile is inherently stable.

Thus, the.CIBL will probably

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disappear into a uniformly stratified air mass when the turbulent m

energy of the upper air layer is' dissipated.

f5' B[tcause the reservoir is heated durin'g operation of ANO Unit 1,

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s the prevalence of the warm water / cold land situation may be greater d

.than would otherwise be expecte. The proposed study will determine the frequency of occurrence of this situation and the magnitude of the water-land surf ace temperature difference, based on the available on-

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f5 site data. These results should allow a conclusion regarding the im-portance of this situation to atmospheric radionuclide dispersion at 4

the ANO site.

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-Should the warm water / cold land condition prove significant, a subset of onsite meteorological data will be selected to meet the cri-teria of onshore air flow together with water surf ace temperature greater than the land surface temperature.

This selected data set will

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then be subjected to an analysis similar to that described in Section 2.2.1 to assess the importance of this feature at the ANO site, and to

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. address the requirements of the monitoring system and the dose assess-ment methodology.

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2.3 0FFSHORE AIR FLOW Because of the limited extent of Lake Dardanelle, the dose assess-ment on land areas on the other side of the reservoir from the ANO site may be Offected by CIBL formation downwind of the site; i.e., occurring over either the water and/or downwind land surfaces. The onsite meteo-rological data cannot provide any specific information on such phenom-c=

k ena occurring downwind of the site.

It may prove possible, however, to relate the information obtained for onshore air flows (Sections 2.2.1 and 2.2.2) to conditions.over the reservoir and over downwind land areas for offshore air flows.

If the results of this analysis do not ffff

. appear to be adequate for the dose assessment, then additional meteoro-logical monitoring locations across the reservoir from the ANO site may lq be recommended.

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The downwind CIBL formation for offshore flows can occur for either the cold water / warm land or the warm water / cold land situations.

g It should be noted that such downwind CIBL formation will, in most cases, enhance dispersion rather than retard dispersibn. For offshore cold water / warm land flows, a plume released in the turbulent land lay-er will. tend to be lofted above any stable layer overwater, thereby in-

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creasing the effective plume canterline height.

For offshore warm water / cold land flows, a pollutant plume released in the stable land

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layer will have the effective plume cross-section enlarged by entrain-ment of the plume into the turbulent layer overwater.

It should also b'e recognized that fumigation and plume trapping conditions can also

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occur under these warm water / cold land configurations and, therefore, enhanced' dispersion can not always be assumed.

Consideration of these conditions, in terms of frequency of occurrence, affect on dispersion, and methodology for Model A adjustment, must be made to properly ad-

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3.0 TERRAIN EFFECTS l

A previous study (Atmospheric Transport Processes at Arkansas Nuclear One, Dames & Moore, 10 September 1976) indicated that signifi-

_ cant channeling of the wind occurs at the Arkansas Nuclear One site;

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I with winds strongly oriented in directions parallel to the Arkansas River valley. However, it was also concluded in the previous study e

that the site is not affected by a " valley wind" recirculation regime,

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which involves up-valley flow during daylight hours and down-valley h

flow (cold air drainage) during nighttime.

The present study will update the 1976 study and, in addition, will develop recommendations concerning the adequacy of the Arkansas Nuclear One meteorological monitoring program to meet the meteorologi-

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cal criteria for emergency preparedness, as stipulated in Appendix 2 of NUREG 0654.

The recommendations wiil address the question of whether or not additional meteorological monitoring sites are required in order to quantify terrain effects and if they are recommended, their antici-pated general locations.

It is tentatively assumed that the main results of the 1976 Dames & Moore study will be found to prevail after review of the more recent meteorological data.

Given the channeling of winds indicated by the measurements at the onsite meteorological tower, the issue of con-cern is a need to consider the effects of major terrain features on wind trajectories from the ANO site.

The presence of a mountain, for example, downwind of the release point can affect the transport direc-tion and the dispersion characteristics of the effluent plume.

The specific effects of downwind terrain cannot be determined from the existing onsite meteorological data. Therefore, the consideration

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of terrain and the incorporation of terrain effects on dispersion in the Model A will necessarily be limited in the proposed study to quali-

}ll tative estimates based on the topographic features near the site and on the application of concepts available in the scientific literature on g

the subject.

The specific qualitative study tasks to be performed in the proposed study are:

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Evaluate the representativeness of the existing meteorological data fce use in the dispersion and transport calculations for e:

radionuclide releases from both Arkansas Nuclear One Units 1 and 2.

E Estimate any needed adjustment or limitation ' hat should be ap-plied to the meteorological data or the dispenf on calculations to account for terrain effects on the dispersion and transport of both elevated and low-level releases from ANO.

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S 4.0 EFFECTS OF HEATED RESERVOIR An objective of the proposed study will be to establish any dif-

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ferences in local atmospheric dispersion characteristics that may be r-engendered by heat dissipation in Lake Dardanelle during operation of ANO Unit 1.

Such effects, if of a sufficient size and frequency,

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should be taken into consideration iii designing the dispersion method-ology to be incorporated into the Model A.

If the available data prove inadequate to characterize these effects or to show them to be insig-g nificant, then the proposed study may result in recommendations for additional studies to provide the necessary data.

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The technique to be employed will te similar if not the same as those presented in Section 2.0.

Subsecs of the available meteorologi-cal data will be generated corresponc'ing to periods when the reservoir was being heated.

The.resulting data subset will then be compared to other data periods and the total data record will then be compared for each of the measured meteorological parameters, as described in Section 2.0, to determine the character':stic atmospheric effects due to the heating of the reservoir.

The study should also indicate the signifi-cance and frequency of occurrence of any effects.

The study will ex-piore any correlation of the effect with onshore and offshore air flow, and with the surf ace temperature difference between land and water.

Recommendations will be presented for the incorporation of these heat reservoir effects into the dose assessment calculations of the dispersion Model A.

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5.0 EFFECTS OF WIND DIRECTION MEANDER

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- The proposed study will address the incorporation into the dose assessment calculations of effects due to meander of wind direction.

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(Wind direction. meander refers to a generally stable atmospheric condi-E tion with steady, low speed winds whose direction varies slowly with time contributing to a decrease in point dosage due to total plume meander.) The existing methods of calculating doses due to releases at the ANO site incorporate a method of handling meander that was develop,

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ed for inland locations.

The application of the presently-used meander correction. terms to the ANO site should be justified, or modified ac-cording to site-specific characteristics.

For example, the appropriate ANO site meander correction may prove to be wind direction dependent.

It is expected that the determination and justification of the proper meander correction terms will primarily depend upon review of applicable studies in the scientific literature on the subject.

The existing onsite meteorological data will, however, also be of value in the study.

Specifically, the dependence of measured values of horizon-tal wind direction standard deviation (o ) on wind direction, wind e

speed, and stability (as measured by the temperature-difference between the tower sensing levels) may provide empirical evidence of the meander affect at the ANO site.

Because the effects of meander may be masked by hourly average ce values, examination of strip chart records of wind direction may be required for selected periods.

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$.... D 6.0 BUILDING AER0 DYNAMIC WAKE EFFECTS The existing methods of calculating' doses due to radionuclide re-leases at' ANO incorporate aerodynamic wake correction factors that de-pend upon the spatial relationships between the effluent release points m-and the onsite plant buildings. The wake correction factors also de-pend upon a constant whose value has been empirically determined.

As for' the meander correction terms discussed in Section 5.0, the applica-tion of the building wake correction terms to the ANO site should be

~ justified,~or modified according to site-specific characteristics.

The proposed. study will include a review of the scientific litera-ture on the subject to provide a recommendation concerning possible

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l~g applicable building wake correction term. The onsite meteorological data cannot be' used in an assessment of building wake effect because the meteorological tower must, of n6cessity, be located outside the influence of the building aerodynamic wakes.

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' r2 is APPENDIX l.?

Additional Data Requirements 1.

Tower meteorological data for selected periods (several years) in computer input format.

2.

High temporal resolution meteorological data.(15 minute or smaller la:].

if averages) for selected periods (several days), or strip chart re-cordings for the selected days.

7 3.

Operating history of Arkansas Nuclear One Unit 1.

4.

All available data on lake surface temperatures that are concurrent b

with the meteorological data period.

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5.

Topographical map of the site indicating the precise location of th'e existing meteorological tower and specific actual and potential release points.

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