March 1988

U.S. NUCLEAR REGULATORY COMMISSION 

)REGULATORY GUIDE 

OFFICE OF NUCLEAR REGULATORY RESEARCH 

REGULATORY GUIDE 3.63 

(Task ES 401-4) 

ONSITE METEOROLOGICAL MEASUREMENT PROGRAM FOR URANIUM 

RECOVERY FACILITIES-DATA ACQUISITION AND REPORTING

A. INTRODUCTION 

Section 40.31, "Applications for Specific Licenses," 

of 10 CFR Part40, "Domestic Licensing of Source Mate

rial," requires that applicants for a license to receive, 

possess, or use source material in conjunction with 

uranium recovery facilities provide information needed 

to assist in demonstrating that operatiohs can be con

ducted to meet the requirements set forth in 10 CFR 

Part 40. Section 40.65, "Effluent Monitoring Reporting 

Requirements," requires that licensees routinely report 

radionuclide releases to unrestricted areas in liquid and 

gaseous effluents. The Uranium Mill Tailings Radiation 

Control Act (UMTRCA) requires the NRC to conform 

to 40 CFR Part 192, which sets standards for the 

control of releases from tailings related to production 

operations. Meteorological data are also relevant to the 

preparation of environmental reports pursuant to 10 CFR 

Part 51, "Environmental Protection Regulations for 

Domestic Licensing and Related Regulatory Functions" 

(see Regulatory Guides 3.8, "Preparation of Environmental 

Reports for Uranium Mills," and 3.46, "Standard Format 

and Content of License Applications, Including Environ

mental Reports, for In Situ Uranium Solution Mining"). 

Meteorological conditions in the vicinity of the 

facility need to be considered in the design and opera

tion of tailings impoundments, the assessment of the 

potential impact of airborne effluent releases, and the 

monitoring of airborne effluents. This guide provides 

guidance acceptable to the NRC staff regarding the 

meteorological parameters that should be measured, the 

siting of meteorological instruments, system accuracies, 

instrument maintenance and servicing schedules, and the 

recovery, reduction, and compilation of data. 

Any information collection activities mentioned in 

this regulatory guide are contained as requirements in

10 CFR Part 40, which provides the regulatory basis for 

this guide. The information collection requirements in 

10 CFR Part 40 have been cleared under OMB Clearance 

No. 3150-0020. 

B. DISCUSSION 

An onsite meteorological measurement program 

employs instrument systems physically located on or 

near the site that are capable of measuring meteorolog

ical information representative of the site vicinity and 

that are operated under the authority of the applicant 

or licensee. The purpose of such a program at a uranium 

recovery facility is to provide the meteorological informa

tion needed to make assessments to assist in demonstrat

ing that the facility design and the conduct of opera

tions are such that releases of radioactive materials to 

unrestricted areas can be kept as low as is reasonably 

achievable. The information is used (1) for the design 

and operation of tailings impoundments and (2) for 

estimating the maximum potential annual radiation dose 

to the public and the environmental impact resulting 

from the routine release of radioactive materials in 

gaseous and particulate effluents. 

Tailings impoundments need to be designed and 

operated so that they do not overfill or breach the 

impoundment restraints, either of which could result in 

offsite releases. The guidance in the regulatory position 

assumes that changes in the quantity of liquid in the 

impoundment are related only to facility operation and 

to the site precipitation and evaporation characteristics. 

The maximum potential airborne annual radiation 

dose to the public and the environmental impact result

ing from routine releases is dependent on the meteoro

logical characteristics of the site. Wind direction, wind 

speed, and atmospheric stability near the site are factors

USNRC REGULATORY GUIDES 

Regulatory Guides are Issued to describe and make available to the 

public methods acceptable to the NRC staff of implementing 

specific parts of the Commission's regulations, to delineate tech

niques used by the staff In evaluating specific problems or postu

lated accidents, or to provide guidance to applicants. Regulatory 

Guides are not substitutes for regulations, and compliance with 

them Is not required. Methods and solutions different from those set 

out In the guides will be acceptable If they provide a basis for the 

findings requisite to the issuance or continuance of a permit or 

license by the Commission. 

This guide was Issued after consideration of comments received from 

the public. Comments and suggestions for improvements in these 

guides are encouraged at all times, and guides will be revised, as 

appropriate, to accommodate comments and to reflect new Informa

tion or experience. 

Written comments may be submitted to the Rules and Procedures 

Branch, DRR, ADM, U.S. Nuclear Regulatory Commission, 

Washington, DC 20555.

The guides are Issued in the following ten broad divisions: The guides are Issued in the following ten broad divisions: 

1. Power Reactors 6. Products 

2. Research and Test Reactors 7. Transportation 

3. Fuels and Materials Facilities 8. Occupational Health 

4. Environmental and Siting 9. Antitrust and Financial Review 

5. Materials and Plant Protection 10. General 

Copies of issued guides may be purchased from the Government 

Printing Office at the current GPO price. Information on current 

GPO prices may be obtained by contacting the Superintendent of 

Documents, U.S. Government Printing Office, Post Office Box 

37082, Washington, DC 20013-7082, telephone (202)275-2060 or 

(202)275-2171. 

Issued guides may also be purchased from the National Technical 

Information Service on a standing order basis. Details on this 

service may be obtained by writing NTIS, 5285 Rort Royal Road, 

Springfield, VA 22161.
that determine where the effluent will be transported 

and its concentration. The following guidance applies 

only to routine releases that occur within 30 meters 

(100 feet) of the ground. 

C. REGULATORY POSITION 

1. Meteorological Parameters 

The meteorological parameters needed for the design 

and operation of tailings impoundments are precipitation 

and an indicator of evaporation. The parameters needed 

to estimate the atmospheric dispersion of radioactive 

materials are wind direction, wind speed, and an indica

tion of atmospheric stability. For obtaining an indica

tion of the atmospheric stability, a method such as one of the following (Refs. 1-4) may be used: insolation

cloud cover and wind speed (Pasquili-Gifford and similar 

methods), temperature lapse rate method, wind fluctua

tion method, split-sigma method, or Richardson Number. 

Precipitation and evaporation data should be totaled 

daily and recorded as monthly and annual summaries. 

The basic reduced wind direction, wind speed, and 

atmospheric stability data should be averaged over a period of I hour. At least 15 consecutive minutes of 

continuous data during each hour should be used to 

represent a 1-hour average. Wind direction data should 

be recorded as quarterly and annual wind rose summaries 

for the 16 compass directions. Quarterly and annual 

wind direction, wind speed, and atmospheric stability 

data should also be compiled in joint frequency and 

joint relative frequency (i.e., decimal frequency) form 

for heights representative of effluent releases. An example 

of a suitable format for data compilation and reporting 

purposes is shown in Table 1. Stability categories should 

be established to conform as closely as possible with 

those of Pasquill (Ref. 4). 

The minimum amount of meteorological data needed 

for a siting evaluation is considered to be that amount 

of data gathered on a continuous basis for a consecutive 

12-month period that is representative of long-term (e.g., 

30 years) meteorological conditions in the site vicinity. 

To determine whether the period during which the 

onsite data was collected is representational, compare a concurrent period of meteorological data from a National 

Weather Service (NWS) station with the long-term 

meteorological data from that NWS station. The NWS 

station selected for this comparison should, if possible, 

be in a similar geographical and topographical location 

and be reasonably close (preferably within 50miles 

(80 kilometers)) to the site. In some sections of the 

country, the spacing between NWS stations may neces sitate the selection of an NWS station more than 

50 miles away. The reduced data and supportive docu

mentation should be retained and should be available 

for review for the period of facility operation.

2. Siting of Meteorological Instruments 

The location of the meteorological instruments should 

represent as closely as possible the long-term meteor

ological characteristics of the area for which the measure ments are being made. Whenever possible, the base of 

the instrument tower or mast should be sited at approxi

mately the same elevation as the facility operation. 

Ideally, the instruments should be located in an area where localized singular natural or man-made obstruc

tions (e.g., trees, buildings) will have little or no influence on meteorological measurements. Measurements 

of wind speed, wind direction, and sigma theta (if 

measured) should be made at least 10 obstruction 

heights away from the nearest obstruction (Ref. 5). To 

the extent practicable, these instruments should not be 

located in the prevailing downwind direction of an obstruction. At most facilities, the instruments could all 

be sited at one location. At some sites, instruments may 

need to be sited at more than one location if the 

meteorological conditions are not similar throughout the 

site vicinity. For example, a site could have a milling 

operation on a mesa where the wind blows predominantly 

from one direction and a tailings impoundment on the 

plain below in the lee of the mesa where the wind is 

most frequently from another direction at a lower speed and with an atmospheric stability regime different from 

that at the release point on the mesa. 

Precipitation and evaporation are usually measured near ground level. If an evaporation pan is used to 

estimate evaporation, a fence or other barrier may be 

needed to minimize animal intrusion. Parameters such as air temperature, atmospheric moisture, and the pan 

water temperature should be monitored as appropriate 

for the type of evaporation model assessment being made. 

For atmospheric dispersion assessments, wind speed 

and wind direction should be monitored at approximately 

10 meters (33 feet) above ground level. For an open 

lattice tower, instruments should be located on booms 

oriented into the prevailing wind direction at a minimum 

distance of two tower widths from the tower to preclude 

substantial influence of the tower upon measurements 

(Ref. 5). Siting of the instruments used to estimate 

atmospheric stability is dependent on the methodology 

used. If instrumentation is used to measure incoming 

solar radiation, it should be located in an area as free as possible from terrestrial shadows. If the temperature 

difference with height method is used to estimate the 

atmospheric stability, the lower temperature-difference 

sensor should be located at 10 meters (33 feet) above 

the ground and the upper sensor should be positioned 

not less than 30 meters (100 feet) above the lower sensor. Aspirated temperature shields should either be 

pointed downward or laterally toward the north.

3.63-2
TABLE I

PERIOD OF RECORD: PASQUILL STABILITY CATEGORY 

Wind Speed at 10-m Level 

Wind 0.22-1.7 1.8-3.5 3.6-5.8 5.9-8.5 8.6-11.2 >-11.2 m/s 

Direction (0.5-3.9) (4.0-7.9) (8.0-12.9) (13.0-18.9) (19.0-24.9) ;>(25) (mph) Total 

N 

NNE 

NE 

ENE 

E 

ESE 

SE 

SSE 

S 

SSW 

SSW 

WSW 

W 

WNW 

NW 

NNW 

Total 

Number of Calms* 

Number of Invalid Hours 

Number of Valid Hours 

*A calm is any average wind speed below the starting threshold of the wind speed or direction sensor, whichever is 

greater. Calms should be included in the table above by assigning to each calm a wind speed that is equal to the 

starting threshold of the wind speed or direction sensor, whichever is greater. Wind direction during calm conditions 

should be assigned in proportion to the directional distribution of noncalm winds in the lowest noncalm wind speed 

category. The directional distribution of calms should then be included in the lowest noncalm wind speed category.

3.63-3
3. System Accuracy and Instrumentation Specifications 

System accuracy refers to the composite accuracy 

reflecting the errors introduced by the entire system 

from the sensor to the data reduction process. This 

system normally consists of sensor, cable, signal condi

tioner, recorders, the humidity and temperature environ

ment for signal conditioning and recording, and the data 

reduction process. The errors introduced by each of the 

separate components of the system should be determined 

by statistical methods (Ref, 6). The accuracies of all 

systems should be appropriate to the use to be made of 

the information over the range of environmental condi

tions expected to occur during the lifetime of facility 

operation and should be consistent with the current 

state of the art for the measurement. 

The accuracies for time-averaged values of each param

eter should be: 

a. Precipitation: as measured by a recording rain 

gauge with a resolution of 0.25 mm (0.01 in.). The 

accuracy of the recorded value should be within 10 per

cent of the total accumulated catch for amounts in 

excess of 5 mm (0.2 in.). 

b. Evaporation: consistent with the current state 

of the art. For information on installation and a descrip

tion of measurement techniques using an evaporation 

pan, see Reference 7. An aspirated shielded device such 

as a lithium chloride or optical dewpoint hygrometer 

(Ref. 8) is suggested for measurement of humidity. Use 

of a hair hygrometer is not recommended. Temperature 

sensors should be consistent with the current state of 

the art for their use. 

c. Wind direction: ±5* of azimuth with a starting 

threshold (the minimum wind speed above which the 

measuring instrument is performing within its minimum 

specification) of less than 0.5 m/s (1.0 mph). 

d. Wind speed: ± 0.2 m/s (0.5 mph) for speeds less 

than 2 m/s (5 mph), 10% for speeds between 2 m/s 

(5 mph) and 22 m/s (50 mph), with a starting threshold 

of less than 0.5 m/s (1.0 mph). 

Parameters not covered above but used to determine 

atmospheric stability should be measured with accuracies 

consistent with the current state of the art for measure

ment of these parameters (Refs. 1, 3). 

The recording system for data acquisition may be 

either analog or digital. Analog recorders should be of 

the continuous strip chart recording type. Digital recorders

should sample data at intervars no longer than 60 seconds 

for wind direction and speed measurements. 

for analog records of parameters SAccuracies thatmay 

vary rapidly with time (e.g., wind direction and wind 

speed) should not be more than 1.5 times those stated 

above. The system accuracies should include the reduc

tion of data from the strip chart recorder to digital 

form. 

4. System Maintenance, Servicing Schedules, and Data 

Recovery 

The systems should be protected against severe 

environmental conditiops such as blowing sand, lightning, 

and icing that may occur at the site. Meteorological 

systems should be inspected at least once every 15 days 

and serviced at a frequency that will minimize extended 

periods of outage and ensure an annual data recovery of 

at least 90% for each individual parameter measured (at 

least an annual 75% joint data recovery for wind speed, 

wind direction, and atmospheric stability). The use of 

redundant sensors and recorders may be an acceptable 

means of achieving this recovery goal. Systems should be 

calibrated at least semiannually to ensure that the system 

accuracies in this guide are met. In areas with high 

ambient aerosol or particulate loadings in the atmosphere 

(e.g., deserts), calibrations should be performed on a 

more frequent basis to maintain system accuracies. 

Sufficient records should be retained and should be 

available for review for the period of uranium recovery 

facility operation to document any activities that may 

iffect the quality of the meteorological data. The 

records should include operating logs and results of 

reviews, inspections, maintenance, calibrations, and 

audits; a description of the types of observations taken 

with the results and their acceptability; and actions 

taken in connection with any deficiencies noted. 

D. IMPLEMENTATION 

The purpose of this section is to provide information 

to applicants and licensees regarding the NRC staffs 

plans for using this regulatory guide. 

Except in those cases in which an applicant proposes 

an acceptable alternative method for complying with 

specified portions of the Commission's regulations, the 

methods described in this guide will be used by the 

NRC staff in evaluating pertinent portions of applications 

submitted to the NRC for new uranium recovery facility 

licenses and for amendments to existing licenses involv

ing major modification of current facilities.

3.63-4
REFERENCES , "

1. International Atomic Energy Agency, "Atmospheric 

Dispersion in Nuclear Power Plant Siting," Safety 

Series No. 50-SG-$3, Vienna, Austria, 1980. 

2. S. R. Hanna, G. A. Briggs, et al., "AMS Workshop 

on Stability Classification Schemes and Sigma Curves

Summary and Recommendations," Bulletin of 

American Meteorological Society, Vol. 58, No. 12, 

pp. 1305-1309, December 1977. 

3. American Nuclear Society, "American National 

Standard for Determining Meteorological Information 

at Nuclear Power Sites," ANSI/ANS-2.5-1984, 1984. 

4. F. Pasquill, "The Estimation of Windborne Material," 

Meteorological Magazine, Vol. 90, pp. 33-49, 1961.

5. R. C. Hilfiker, "Exposure of Instruments," in Air 

Pollution Meteorology, USEPA Air Pollution Training 

Institute, Research Triangle' "Park, 'North Carolina, 

September 1975. 

6. C. E. P. Brooks and N. Carruthers, Handbook of 

Statistical Methods in Meteorology, M.O. 538, Chap

ter 5, Her Majesty's Stationery Office, London, 

1953. 

7. U.S. Department of Commerce, Substation Observa

tions, Weather Service Observing Handbook No. 2, 

Chapter 5, 1972. 

8. L. J. Fritschen and L. W. Gay, Environmental Instru

mentation, Chapter 6, Springer-Verlag, New York, 1979.

3.63-5
VALUE/IMPACT STATEMENT

A draft value/impact statement was published with Task 

ES 401-4 when the draft guide was published for public 

comment in September 1985. No changes were necessary, 

so a separate value/impact statement for the final guide

has not been prepared. A copy of the draft value/impact 

statement is available for inspection and copying for a fee 

at the Commission's Public Document Room at 1717 H 

Street NW., Washington, DC, under Task ES 401-4.

3.63-6
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