Recommended Procedures for 

Measuring Radon Fluxes from 

Disposal Sites of Residual 

Radioactive Materials 

Manuscript Completed: February 1983 

Date Published: March 1983 

Prepared by 

J. A. Young, V. W. Thomas, P. 0. Jackson 

Pacific Northwest Laboratory 

Richland, WA 99352 

Prepared for 

Division of Waste Management 

Office of Nuclear Material Safety and Safeguards 

U.S. Nuclear Regulatory Commission 

Washington, D.C. 20565 

NRC FIN 82216 

NUREG/CR-3166 

PNL-4597 

ABSIP.P.CT 

This report recornmenrls instrurr,entc.tion and metr,ods suitable for measuring 

radon fluxes t·manatinq h·om co·n~red d·isoosai sites of residual radioactive 

matedal~. such as urc.rdum mill tan·in~rs. Problems of spatial and temporal 

var·iahons 1n radon flux are discussed and the advantages and disadvantages 

of severa·l instriJments ar·e examin<:1L /\year-long measurement program and 

·3. two rnonth measurem(~fl~ rnethodoloq:; ore then oresented based on the inherent 

difficulties of measufii·:q avenqP r·c:.don flu;~. O'J8r ;:~cover using the 

recorrrnenJed ins trumer: t,J +_ion. 

l.' 

TABLE OF CONTENTS 

]. Introduction •••••••••••••••••••• 0 • 0 • 0 • 0 • 0 • 0 •••••••••••••••••••• 1 

II. Spatial and Temporal 

Variations in the Radon Flux .•.•.•.......................... 2 

1. Spatial Variations 

2. Temporal Variations 

A. Introduction 

B. Moisture Content 

••••••••••• 0 0 0 0 ••••••••••••••• 0 •••••••••• 2 

3 

3 

3 

C. Ice . . . . . . . . . . . . . . . . . . . . • . • . . . . . . . . • . • . . . . . . . . . . . . . . • . • . • 4 

D. Pressure 

E. Wind Speed • 0 0 ••••••••• 0 • 0 •••••••••• 0 •••••••••••• 0 •••••• 

F. Season •••••••• 0 0 ••••• 0 • 0 •• 0 •••••••••••••••••••••• 0 0 0 ••• 

G. Diurnal Variations ••••••• 0 • 0 •••••••••• 0 • 0 •••••••••• 0 0 •• 

H. Trends with Time 

III. Radon Flux Measurement Techniques •••••• 0 0 •••••••••• 0 ••••••• 0 • 0 • 

1. Introduction •• 0 0 0 ••••••••• 0 •••••••••• 0 •••• 0 •••••••••••••••• 

2. The Charcoal Canister Method ............................... 

3. The Flow Method ............................................ 

4. The Accumulation Method .................................... 

5. Track Etch® and Thermoluminescent 

5 

5 

5 

6 

6 

7 

7 

7 

8 

10 

Dosimeter (TLD) Detectors .........•..•................. 11 

IV. Procedures for Conducting Radon Flux Surveys 

1. Summary of Recommended Procedures .......................... 

2. Gamma-Ray Surveys .......................................... 

3. Radon Flux Sampling Grid ................................... 

4. Time Schedule of Flux Measurements ......................... 

A. Year-Long Measurement Series ........................... 

v 

12 

12 

13 

13 

14 

14 
B. Two-"'lonth Measurement Series ........................ " 17 

,, ' . Ca "I i brilt l r;n of Radon Flux r~eaSUl'ing iJev ~ ces 

Reference<:. 

vi 

l.7 

20 
J. A. Young~ V. W. Thomas anG P. 0. Jackson 

1. lntroductian 

The U. S. Environmental ProtecUo11 Agency (EPA) inter·im environrner1tal 

stanaards for the dis;Josal of residual radioactiVE: materials from inactive 

uranium ;:>rocessing sites were publi"shed in the Fedc:··ai Reg·i~,ter in January 

193) (tJ.O CFR. 192)~. P,lthough the Department of F.:1ergy (DOE) has tt\e primary 

respons·ibility for the implementation of thesE: EPr1 st:J.?"IdiFds, PL~-9S-604 

requires that the i~uclear Regulatory Comfilissi,Jn U~RC) concur in remedial 

actions. One of the requirements of the interi~l st~ndards is that disposal of r·esHua1 rad:Jactive materials from inactive uranium processing 

sites shall be conducted in a way that provides a reasonable fxpectation 

t'nat the average annual l'elease of radon-222 from the disposal sites to 

t.he atmosp~1er0 by residuai radioactive materials fcd.lovJing -jispJSal will 

not exceed 2 pCi/mLsec for at ·!east 1000 years fullm~·in~, disposal. 

Howc.-.'er, the EPA h<lS recently proposed t1at the starHjad be changed to 

requ'1re that the flux shall not exceed 20 pCi/rn2·-sec fol" at least 200 

yr::ars, dfld to the extent practlcable, 1000 Y<':!lil'S. r~~ lS fC:JI.pectJ:d that 

the radon flux standard will be interpreted to reqJir'e t~1at t'Je a.nnual 

avc;ragt: flux from a tai lhgs pile, rathe·r tha:1 t.re f·r,lx ;lt any location 

on the pile, snal I nc·t ex,:eed the st::..ndard. 

It is anticipated ·that the reduction Jf rcH;or. E!iTJiss·;c;ns from disposa1 sitt~s will be accr;mp1ishec! by covering the taiL:-.qs vlith a layer, or 

layers, of earthen material. Hm1ever·, it is pos~ibie that a layer crF 

materia·! such as asphalt will also be laid down w act as a radon b.J.rrier·, 

The cover will decrease the em·ission of radon into the atmosphere because 

of the rall"ioactive aecay sf the radon during its difFu:~·(cn through t.he 

cov,;r. Tht; radr)n emiss~on will also be decreased because the cover w~ ll 

reduce t~12 concEntration gradier1t and therefo~e the rate af diff~sion of 

radon fl-.:Jnl the ta'r1ing-~;. 

The ra.don f 1 ux T'r·om a. co·vl~red ta 1 ·1 i ngs pi i e \vi 11 cor.:e from both th2 

tai1ings JJ"l'j t.hE· covering mater-iai. The radon emission standard w"ill r;e consid~1·e~ to b~ sati~fien for a disposal site ,~ the radon flux is less 

than 1)r eqi1il.i to the ~::andat'd p~us th~~ exhalation rate of the cover 

fl"ID.tl'ria';. r'•ut:es f'·onl natural soli~: ere ty~lica11y 0.5 to 1 pCi/rn 2-sec, 

nut f1~.;xes up to sr:ve~'a.l tlrr1es thest: values ai--r; ;·J,.,t : .mustEl.·l. Therefore, 

the radon fluxes from possiblE: cover· n;,YJ:e(ie:ls at F:Ci"'1 disposai site 

:,•wuld be determiqed as paft of the di~[E·""~l ~,·:,,;·. 

Tile f"ind·! ~-Pi\ ~;t..:;..,clard cor:cc,~.1 ing radon f"luJ:(:; :e.-_'1 t••.: ':: L11: form .)f 

either d perforwance standard or a design objective. A )trT0rlndnce 

stanoatd l·iould require that radon f1Jx rneasur?rnPnt:~ tle perL·l''IIC!:i t'.J 

v-2r .. 1f~J compliance. 1\ desi:_;r1 obj~:ctive wo,1ld r""Cil .• -;t'f. c;nly tha.t U:c covtJ 

1 
be designed to lower the calculated radon flux below a given value. 

Flux measurements would not be required to verify compliance with a 

design objective. However, radon flux measurements would still be useful for the experimental purpose of verifying that the design cover is 

functioning as planned. 

This report has been prepared for NRC to recommend procedures for 

measuring radon fluxes from disposal sites of residual radioactive material after they have been covered to reduce the radon flux. It will 

recommend sampling programs, instrumentation, analytical procedures, 

data reporting formats, and statistical analysis of the data that should 

be used in the determination of radon fluxes. 

II. Spatial and Temporal Variations in the Radon Flux 

1. Spatial Variations 

The determination of average radon fluxes from disposal sites 

is complicated by the fact that there may be large spatial and temporal variations in the flux from a given disposal site. The flux 

from a tailings pile varies with location on the pile because of 

variations in thickness of the pile and variations in the particle 

size, 226Ra concentration, moisture content, and emanating power of 

the material added to the pile (the emanating power is the fraction 

of the radon atoms produced by 226Ra that escapes the crystal lattice and is free to diffuse). Measured radon fluxes have varied by 

more than an order of magnitude with location on tailings piles 

(Silker and Heasler, 1979; Ford, Bacon and Davis Utah Inc., 1981). 

According to Leggett, et al. (1978), the number of locations at 

which a parameter must be measured to determine its average value 

with a precision of 25% at the 95% confidence level is given by 

Number ~ 45(coefficient of variation) 2 ( l ) 

The coefficient of variation of the radon flux measurements 

made by Silker and Heasler (1979) at several locations on the Grants, 

New Mexico tailings pile was 0.74. Freeman (1981) found that the 

coefficient of variation with location was 0.84 for the Grand Junction 

tailings pile. The coefficients of variation of the radon flux measurements made by Ford, Bacon and Davis Utah Inc. (1981) also averaged 0.84 for several uncovered tailings piles. According to 

Equation (1), the number of locations at which the flux would have 

to be measured to determine the average within 25% at the 95% confidence level would be 25 if the coefficient of variation were 0.74, 

and 32 if it were 0.84. 

The variation of the radon flux across a covered tailings pile 

could be somewhat less than that across an uncovered pile because 

horizontal diffusion of radon in the cover material would be expected 

2 
to lower horizontal concentration gradients. However, if the cover 

material were not uniform, or if cracks developed in it, the spatial 

variation of the flux from a covered tailings pile could be greater. 

The coefficient of variation of the radon flux measurements made by 

Ford, Bacon and Davis Inc. (19Bl) averaged 0.66 for several tailings 

piles covered by about six inches of soil. According to Equation 

(1), measurements at only 20 locations would be required for this 

coefficient of variation. However, Leggett, et al. (1978) also recommends that measurements be made at a minimum of 30 locations. It 

therefore appears that in most cases flux measurements should be 

made at 30 locations, although in some cases measurements of more 

locations would be required because of higher variations in the radon 

flux. 

2. Temporal Variations 

A. Introduction 

The radon flux from a given location at a disposal site 

will also show considerable variation with time as a result of 

changes in meteorological conditions, moisture content of the 

tailings, and perhaps settling of the cover material. According 

to Baver (1956), the meteorological factors influencing the 

radon flux are, in order of decreasing importance, rainfall, 

variations in barometric pressure, variation of soil and atmospheric temperature, and wind speed. He estimated that together 

these factors are responsible for less than 10% of normal soil 

aereation. 

B. Moisture Content 

The radon flux will depend greatly upon the moisture content 

of the tailings and cover material. The fraction of radon atoms 

produced by 226Ra decay that escape the crystal lattice increases with moisture content. When a 226Ra atom decays by 

alpha particle emission the radon atom that is formed recoils 

in a direction opposite from that taken by the alpha particle. 

If the recoiling atom comes to rest inside a grain of the 

material, it is very likely to remain entrapped, but if it 

comes to rest in a pore it will be free to diffuse into the 

atmosphere. However, the pores of compacted natural materials 

are likely to be smaller than the recoil range of radon atoms 

in a gas, so a recoiling atom that enters a gas-filled pore is 

very likely to cross the pore and become entrapped in a neighboring grain (Tanner, 1980). The recoil range in water is about 

one hundred times less than that in air, so the probability 

that a recoiling atom will stop in a pore is greatly enhanced 

if the pore is water-filled. 

3 
The rate of diffusion ir: ,,·utei' is rr.:ucl: le5:;; t!.dn th.1t in 

air so the rate of diffusion into the <J.t.n::.;·.srl-]ere of the. radon 

atoms that have escaped tn2 uystctl lattice .vll"i be lower-ed by 

increasing the moisture ccr:te:n. of e1thE.r thl:.' tJil ings cr th·~ 

cover material. Therefc.re, inuec\se::l moistur·e content could 

either· raise or lower the ;ad,Jr Fiu:<. .!\cco"'c.ling to ~1om~ni~ .c:t 

al. {1979), the radon flu:( f·:·orr: dornf'·;-:;ic utcrdum ore.s v;::,r·i2s 

only slightly with rnoistur·e c-nL-::Tr b:;t.,t~~t~n lO% and 81,;% s;;t;;-

ration. On the other hand, \\oqv';, et. ,,·1. (1979) -round that 

the flux from tailings decreJsed 11y i1 ~--i:l.ct,_H' of 100 when tb~ 

moisture content increased from dry to saturatitJn. The ?PPM'f'nt 

contradiction of these teS'J:t') is exp1ain-c:c! b_y th: nbser-.. at.-ions 

of Strong and Levins (1982}, wno 1r03sureJ l~e f1ux a~ radon 

from a column of mill taflillClS as~ LJn(tion of moisture CtJrit.enl.-, 

They found that the fl1•x lnCrt:aS·2d by c. ~act,)r of 3.5 wilcn the 

moistut'e c0ntent increased f:or.·, 1J.2 to 5.7% hy ',·;e-19ht r:. t.~u::~ 

increased only s 10w:.Y ·H·iti, in::r·e.a·; :l'l~; rnn·is~~·.:re ccntent unt-il 

saturation was reache~ .. ot ·,..,~\lich t-i-~1::' ~-:~ dccru·;eG sharp-!:y. 

They estimated that tf-!e r·a.Jnn flux f;'.:X·' an infinit2ly th~ck 

tailings pile :hat was s~t~rdted ~itn :._,~~r ~st:l~ l>e 1nl~ ~~ 0f 

that from a one contain-~r:''l 5. 7% ··<~-:.t::·,·. 

According to Mc~eni, et ~:. (1Q7?], -f~~~~.:r~ content of 

0.2% is typic<1l for dry Li:·;r,~s ir; a : .. Y'th,;>:st:.:.r'n ~lirnat2. 

Increasing the moisture 1:Jnt~~~ ~t ~~~~e ~2il i~gs w~uld tc (~X· 

pected to incr9ase the flux. 1-IO"'iitv'ei) n th<; tai'lin9s ,~-~~rc~ 

covered by a ; a._yt;r of eor-til~n rn3.ter i a. ·1, i ncr~ac; in~ th!~ n;<J, s- ~utc 

content of the cover rr,ater i G.1 ,_._.:-_,,.; i d dt::::n; 3.52 the rate of 'j iffusion of radon throtl9h the cover" J::c! Lil!l'i' the f:ux. ~\ he:;vy 

rainfall mig~1t not immediat~~Y it.crease th~ moisture contetl~ cr 

the tailings, but it would i~cre5S2 the mo1stute content of th~ 

cover material, thereby greatly decr~as1ng the ra~on fllil. 

Therefore, flux mf.:a :;vre111en ts mac::~ f·~' hw~ n,J ct 1-'.ea\'Y n. j n sh:)u ~ d 

not be used t0 .jr·t,=rmine avE-rage f\:::~:s. 

C. Ice 

Several investigator5 have dlss ot~t-r-v2n tn~t a cav~r :1f 

ice will sharply reduce the radDn fl'ix -(r-~>rl ,·;rlJst.al sur·f.K25, 

Pearson a.'ld Jones ( 1965, 1966) o:;s\:rv,~d t:"-etl. the flux inc:-easc-d 

by a factor of two or more when a w:r.ter· :f;c~w r~sulted ·ir, t!",e 

disappearance of iln ice coJer. Count~~s (lq77) observed ti,Bt 

a 1000-fold reductior1 in the flt!X fror" J tQi1ings pile persisted 

for several weeks fcllmv·,'r1g the formt-i'_jr; ftf an ·i.-:-t.· cover on 

the plle. Therefov--~, the aw~·:cqr; i··:>· f-~_..,, •J ,._,;_iJ',ngs ;:;i> 

should not be deterrr·inecl by f 1dx "'·C\3.',.~r-:•!H!1.S :1·:d·~ wh"'~~ ,;hr: 

pile is coverecl with ~ct. 
D. Pressure 

Decreasing atmospheric pressure draws interstitial gas 

toward the surface. thereby increasing the radon flux; and increasing pressure pumps it away from the surface, thereby decreasing the flux. According to Clements and Wilkening (1974) atmospheric pressure changes of 1% or less cause 50 to 100% changes 

in the exhalation rate of soil, with the actual change depending 

upon the rate of change of the pressure and the duration of the 

change. A frequently quoted figure is that a 1% atmospheric 

pressure change will cause approximately a 60% change in the 

radon flux (Colle, et al., 1981). Bogoslovskaya, et al. 

(1932) found that the flux from uranium ore would vary by an 

order of magnitude with atmospheric pressure, even if the ore 

were buried five meters below the surface. 

E. Wind Speed 

It is not known for certain how significant a role wind 

speed plays in determining radon fluxes. The uncertainty is 

partly due to the fact that radon flux measuring devices interrupt the flow of air across the material whose flux is being 

measured. Therefore, it is not possible to be certain that the 

flux from the material is the same as it 'Nould be if the flux 

measuring device were not there. Pearson and Jones (1966) found 

no obvious correlation between wind speed and the radon flux 

from grass-covered soil in Illinois at the very low wind speeds 

that normally occurred near the scil surface. However, at 

abnormally high wind velocities the flux increased linearly 

with velocity. Kraner, et al. (1964) measured higher fluxes on 

unstable days with higher wind speeds. They postulated that 

the increase occurred because the microoscillations in barometric pressure that are associated with wind gave rise to 

turbulent pumping that resulted in the exchange of a layer of 

soil gas with radon free air from above the surface. Israel 

and Harbert (1970) measured about a four-fold increase in the 

radon flux from soil when the wind speed increased from 1 to 13 

msec-1. However, their measurements were performed on moist 

soil, and they concluded that the increase in the flux was due 

to a decrease in the soil moisture content at higher wind 

speeds. Because of the possibility that radon fluxes increase 

with increasing wind speed, fluxes should not be measured during high winds. 

F. Season 

The radon flux can be expected to show seasonal variations 

at locations that show seasonal variations in factors such as 

soil moisture or ice cover. Megumi and Mamuro (1973), however, 

found little seasonal variation at Osaka .. Bakulin (1969) found 

5 
that the seasonal variations were not more than 10%, with maximums occurring in summer. Because of the possibility of systematic seasonal variations, the radon flux should be measured at 

uniform intervals throughout the course of a year in order to 

obtain a reliable value for the average flux. 

G. Diurnal Variations 

The radon flux may be expected to show diurnal variations 

because of (1) the diurnal pressure wave, which produces a minimum in the pressure in the afternoon; (2) turbulent mixing in 

the atmosphere which leads to an increase in the flux during 

the day; and (3) changes in convective flow due to temperature 

differences in the soil between day and night. Pearson and 

Jones (1966) found that the flux from soil in Illinois was highest near sunrise and in the mid-afternoon when the atmosphere 

was most turbulent near the soil surface. The maximum (hourly) 

radon fluxes during the day were around seven times the fluxes 

measured during the stable nighttime. Duwe (1976) concluded 

'f"rom a study of the measurements by seve11 investigators that 

the most likely pattern of radDn flux is a broad nighttime minimum, an increase during the morning to an average value of about 

2.5 times the minimum, a decrease during the early afternoon, 

and a second increase during the late afternoon to an average 

value of about 1.5 times the minimum. Duwe also concluded from 

model calculations that soils with low permeability would show 

lower diurnal flux variations. Because of the likelihood of 

diurnal variation~ in the radon flux, radon flux measurements 

should, if possible, be made over time periods that are multiples 

of 24 hours. 

H. Trends with Time 

Radon fluxes from stabilized tailings piles could show 

systematic trends with time because of factors such as (1) changes in the moisture content of the tailings and cover material. 

(2) development of fissures in the cover, (3) erosion, (4) the 

action of burrowing animals, and (5) the growth of vegetation. 

Changes in the moisture content would be particularly likely to 

cause significant trends. If the cover material were sprinkled 

with water during its addition, the radon flux might be expected 

to increase rapidly with time at first, and then change more 

slowly after that as equilibrium moisture content was approached. 

This author is not aware of any available data that could be 

used to determine the time period required for moisture content 

and radon fluxes to approach equilibrium leve1s. The time required 

would depend upon the climate and the nature of the cover material. 

Therefore, radon flux measurements at a few locations on at 

least two tailings piles should be made at least once a month 

for about a year-to determine the time that should be allowed 

6 
for the fluxes to approach equilibrium values before extensive 

measurements to determine the average flux are initiated. After 

the fluxes have approached equilibrium values on these two piles, 

the flux measurements should be continued on a once a year sampling 

schedule for as long as possible to determine the nature of any 

long-term trends. 

III. Radon Flux Measurement Techniques 

1. Introduction 

Several investigators have used various types of accumulators 

or charcoal canisters to measure radon fluxes. However, at the present 

time there exists no facility that can be used to accurately calibrate 

these flux measuring devices under varying meteorological conditions. 

The flux is generally calculated by dividing the total quantity of 

radon collected in the device by the area covered by the device and 

by the sampling time. Therefore, it is not really possible at the 

present time to compare the accuracies with which the various devices 

measure the radon flux. 

2. The Charcoal Canister Method 

Several investigators have employed various types of passive 

charcoal canisters to measure the radon flux. The canister containing charcoal is placed directly in contact with the surface. The 

charcoal adsorbs the emanating radon, and after a period of time 

ranging from a few hours to a few days the charcoal is removed and 

the average flux determined from the quantity of radon adsorbed on 

the charcoal. The radon is usually measured by sealing the charcoal 

in an air tight container, allowing the charcoal to sit for a few 

hours to allow the short-lived radon daughters to come to equilibrium 

with the radon, and counting the gamma-rays emitted by the shortlived radon daughter, 21

~Bi, using either a Nai(Tl) or a germanium 

diode gamma-ray spectrometer. However, the radon can also be desorbed from the the charcoal and counted in a ZnS scintillation 

detector cell. The charcoal canister method has the advantage that 

many measurements can be made inexpensively because of the low cost 

of the canisters and the ease with which they can be deployed and 

recovered. 

Countess (1977) has used a modified U.S. Army Mll gas mask 

charcoal canister to measure radon fluxes. This canister covers an 

area of 87 cm2 and contains 148 g of activated charcoal. Countess 

(1977) reports that a lower limit of detection of 0.03 pCi/m2 -sec 

can be obtained for a four-day exposure using this canister. This 

detection limit should be more than adequate for determining whether 

the flux is greater than 2 pCi/m2

-sec. Mine Safety Appliance Co. 

manufactures an activated charcoal cartridge type GMA No. 459315 

that is suitable for measuring radon fluxes. It will cover an area 

7 
of 41 cm2 and contains 36 g of charcoal (Countess, 1977). It is 

also quite easy to construct charcoal canisters using PVC pipe or 

similar material. 

MacBeth, et al. (1978) reported that the prec1s1on and accuracy 

of the charcoal canister method is ±15%. This figure may be optimistic, however, because a two-laboratory comparison study performed to 

determine whether the actual analysis of the charcoal canister is a 

major contributor to variations in measured fluxes found that the 

average difference in the measurements between the two laboratories 

was 16% (Horton, 1979). However, with careful counter calibration 

it should be possible to measure the radon with a considerably better 

precision than this. 

Charcoal canisters have the drawback that they can on'ly be used 

to measure the flux over a very limited area for a limited period of 

time. Therefore, they should be used to measure the flux at several 

locations and at several times at each location to determine the 

average radon flux. 

Magum1 and Mamuro (1972) increased the measurement area to 

2,450 cm 2 by spreading the charcoal over a netting laid on the 

ground. The charcca1 ~tJas isolated from the atmosphere by covering 

1t witr1 P'JC film. l<isleleski, et al. (1980) increased the area 

measured by attaching an army gas mask canister to the center of a 

collector lid covering an area of 2,300 cm 2 • However, the diffusion 

of the radon under the collector lid to the charcoal canister may be 

too slow to prevent the radon concentration under the lid from rising 

to the level at which it lowers the net radon flux from the emanating 

surface, so this method could give results that are too lo~;;. Therefore) 

it should not be used to measure radon fluxes until it can be proved 

to provide accurate measurements. Any time the charcoal canister 

method is used, care should be taken to minimize the distance between 

the charcoal and the emanating surface to prevent the radon concentration from building up above the emanating surface. 

3. The Flow Method 

Several investigators have measured the average radon flux over 

a relatively large area by circulating the air under a collector 

through a charco~l bed. Pacific Northwest Laboratory (PNL) developed 

a recirculating, pressure balanced, flow-tllrough radon flux measuring 

system that uses a 76 X 122 X 5 r:m (9300 cm 2 area) aluminum tent to 

cover the area to be measured (Thomas, et al., 1982; Fr-eeman, 1981). 

A diaphragm vacuum pump draws air through a drierite column to remove 

water vapor, through a filter to remove particulates, and then through 

an activated carbon trap to remove radon. The carbon trap consists 

of a 4.8 em diameter convoluted tube that is filled with 400g of 

Pittsburgh Carbon Company 8-12 mesh activated carbon. This trap has 

8 
been shown to absorb 99.9% of the radon in air that is circulating 

through the trap at a rate of 2 liters per minute at a temperature 

of 44°C (Hartley, et al., 1981). This sytem is sealed to tailings 

by pushing the lip of the tent into the tailings. It is sealed to 

asphalt by means of caulking compound. After about four hours of 

sampling, the charcoal is transferred to a petri dish and counted 

after a few hours delay for 214Bi using either a Nai(Tl) or an 

intrinsic germanium gamma-ray spectrometer to obtain the radon concentration. 

The coefficient of variation of the radon flux across the area 

covered by the PNL flux measuring system is expected to be much less 

than the coefficient of variation between the fluxes at widely separated locations on the tailings pile. Freeman (1981) found that the 

coefficient of variation of the fluxes measured at different locations on the Grand Junction tailings pile using the PNL system was 

0.84. This is much larger than the coefficient of variation of 0.29 

that Silker and Heasler (1981) measured between four locations within 

an area of 200 crn 2 using a 41 cm 2 area charcoal canister. Countess 

(1977) found an even smaller coefficient of variation between multiple 

measurements of radon flux over a one to two square meter area on 

several test surfaces. He found that the coefficient of variation 

ranged from 0.06 for an outdoor location in the phosphate region of 

Florida to 0.15 for measurements on soil in New Jersey. The variation in the flux across a covered tailings p"ile will be dependent 

upon the degree of heterogeneity of the tailings and cover material. 

However, if it is assumed that the coefficient of variation of the 

flux (as measured by a charcoal canister) across the PNL system will 

be 0.29, and the coefficient of variation in the flux (as measured 

by the PNL system) across the entire tailings pile will be 0.84, 

then it can be calculated that using a charcoal canister rather than 

the PNL system will only increase the coefficient of variation of 

the measured fluxes from 0.84 to {0.842 + 0.29 )~ = 0.89. According 

to Equation (1), this would only increase from 32 to 36 the number 

of locations at which it was necessary to measure the flux in order 

to determine the average flux with a 25% accuracy at the 95% confidence level. It therefore appears that the average flux over a large 

area could be determined just as accurately with a charcoal canister 

as with the PNL system, although a few more measurements might be 

required. It should be remembered also that a charcoal canister can 

be used to measure the radon flux over a longer time period than 

can the flow system, so a single measurement using a charcoal canister 

would probably provide a better estimate of the temporal average 

than would a single measurement using a flow system. In summary, 

comparisons between a charcoal canister system ard a flow system 

indicate that charcoal canisters are more effect·ive in terms of cost 

and effort for measuring the average :aden flux across a large area 

such as a rec~aimed disposal site. However, the accuracies of the 

two techniqu~s must still be compared using a calibration facility befon~ a choice can be made between them. 

9 
4. The Accumulation Method 

The accumulation method involves the measurement of the radon 

that accumulates in an open-faced container that is inverted and 

sealed to the emanating surface. The accumulator is generally sealed 

to a soil surface using wet bentonite or by imbedding the rim of the 

accumulator several centimeters into the soil. The accumulator is 

sealed to rigid surfaces such as bui1ding materials using epoxy resins 

or other caulking agents. Accumulators of many sizes and shapes 

have been used, with large barrel accumulators being popular. 

The radon flux is determined by measuring the initial rate of 

change in the radon concentrations in samples of air that are withdrawn periodically from the accumulator through a sampling port. 

The air in the accumulator is generally mixed with a small fan to 

insure that representative samples are obtained. The flux is calculated using the equationE ~*(~~+An) (Z) 

where E ~ radon flux (a toms/ cm 2 -sec) 

v ~ volume of accumulator (em') 

A ~ surface area of accumulator (em') 

n ~ radon concentration (atoms/em') 

t ~ time (sec) 

A = radon decay constant (sec-1) 

The rate of change in the radon concentration in the accumulator 

can be used to calculate the radon flux only until such time as the 

concentration reaches a level that is a significant fraction of the 

concentration in the emanating material. At that time back diffusion 

into the emanating material will decrease the concentration gradient 

in the emanating material and thereby lower the net flux into the 

accumulator. Wilkening, et al. (1972) recommends that the concentration in the accumulator be kept below 10% of the soil gas concentration at a depth of 13 em. For most soils this concentration is 

reached in a matter of hours. 

Errors may arise in the measurement of radon fluxes using accumulators because of errors in the measurement of the quantity of r'adon 

in the accumulator, and because the accumulator (1) changes the flux 

by disturbing the soil, (2) changes the soil temperature, which may 

change the thermal stability or the amount of radon adsorbed onto 

soil grains, (3) reduces the flux because 0f increased radon concentrations inside the accumulator and (4) changes the temperature, 

wind velocity, and turbulence above the soil surface (Duwe, 1976). 

However, the same difficulties are faced by the charcoal canister 

and flow methods. 

10 
Wilkening (1977) reported that typical error limits for the 

accumulation method are 6 to 10%. Bernhardt, et al. ( 1975) performed 

the most extensive evaluation and verification of the accumulation 

method. They found that although the counting errors were generally 

less than 5% for each radon sample, the precision for replicate flux 

measurements was typically 20% for fluxe~ of 100 pCi/m 2

-sec and 50 

to 100% for fluxes of less than 10 pCi/m -sec. 

The accumulator has the advantage that it can be used to measure 

the radon flux over a larger area than is generally measured using a 

charcoal canister. However, sampling time is limited because of the 

build-up of radon in the accumulator. The accumulator is a much 

more complicated and expensive device than a charcoal canister, and 

the measurement of radon is more complicated using the accumulator. 

It also appears that the precision of accumulator measurements at 

low radon fluxes is not very good. These factors would seem to indicate that the accumulator method would be a less satisfactory method 

for conducting radon flux surveys than is the charcoal canister method. 

However, the accumulator method could still be the method of choice 

if it could be shown to provide more accurate flux measurements than 

other techniques. 

5. l!:.<!C2t..£!:ch"' and Thermoluminescent Do~i_me-t:_er (TLD) Detectors 

Radon fluxes show large temporal variations, so average annual 

fluxes should be determined from several measurements during the 

course of a year if a measurement technique is used that is not capa- ble of making a measurement over a period of longer than a few days. 

Therefore, it might seem more practical to measure the radon flux 

using a Track Etch"' or TLD detector which was buried beneath the 

soi 1 surface, or attached to the surface of a material such as asphalt 

or concrete, and left in place for a year or more. Extensive measurements of soil gas concentrations have been made using these devices 

by many investigators, especially during the exploration for uranium 

deposits. However, the Track Etch® and TLD detectors measure the 

radon concentration rather than the flux. Therefore, the radon concentrations would have to be measured at several depths and the effective diffusion coefficient determined before fluxes could be calculated from these concentration measurements. Alternatively, it might 

be possible to derive approximate empirical factors relating singledepth radon concentrations to radon fluxes from simultaneous measurements of concentration and flux for var·ious materials. Wilkening, 

et al. (1972) found that there was a good correlation between radon 

flux and soil gas concentration near Socorro, New H'exico. However, 

the derived factors m·ight be expected to be differ·ent for different 

mat.eri a 1 s, and might be expected to change with meteoro logical cond itions and soil moisture. Therefore, it appears that the measurement 

of radon fluxes using Track Etch"' or TLD detectors would not be 

practical until extensive simultaneous measurements of concentrations and fluxes had been made to derive empirical factors relating 

cJncentrations to fluxes for various materials and conditions. 

11 
IV. Procedures for Conducting Radon Flux Surveys 

1. Summary of Recommended Procedures 

A gamma-ray survey should be performed using a detector system such as a micro-R-meter to measure the gamma-ray exposure rates at 

an elevation of 80 to 140 em at the grid points of 350 by 350 em 

grid. If an increase in the exposure rate is detected at any location, a search around that location should be made at the surface 

for elevated contact readings. Radon fluxes should be measured at 

locations showing exposure rates greater than three standard deviations above the average for the tailings pile. Flux measurements 

should also be made at enough locations on a rectangular grid to 

bring the total number of measurements up to the number required by 

Equation {1) or to 30, whichever is greater. 

Each flux measurement should be made over as long a period of 

time as is practical, preferably two or three days. The measurements should not be made after a heavy rain, when there is an ice 

cover, or during high winds. If the cover material has been sprinkled 

wlth water during application, then flux measurements should not be 

begun until the covered tailings pile has dried out enough so that 

the radon fluxes have stopped increasing rapidly with time. Repeated 

measurements at a few locations on at least two of the first piles 

measured should be used to estimate how long a time should be waited. 

Ideally, the flux measurements should be made every other month over 

the course of at least one year. However, if the flux measurements 

are being made to determine whether the flux exceeds a performance 

standard, it may be necessary to complete the measurements within a 

shorter period of time, so that a decision can be made as to whether 

further remedial action is required. In that case, flux measurements 

should be made once a week for two months at each location. 

If the measurements are being made to determ1ne whether the 

average flux exceeds a performance standard, they should be discontinued whenever it becomes possible to be reasonably certain whether 

or not the average flux will exceed the standard. The measurements 

should be discontinued if at any time it is calculated that there is 

either a less than 5% probability that the average net flux will be 

greater than the existing flux standard, or a greater than 95% probability that the average net flux wi11 exceed the standard (net flux 

equals total flux minus the flux from the cover material). After 

the measurements have been completed, the average and the coefficient 

of variation of the measured fluxes should be used to calculate the 

probability that the true average flux exceeds the standard. 

On the other hand, if the flux measurements dre being made to 

determine whether the cover is performing as designed, fluxes from 

at least a few tailings piles should be measured every other month 

for at least one year, because the fluxes could change systematically 

12 
with time as a result of factors such as changes in soil moisture, 

erosion, settling of the cover material, growth of vegetation, and 

the action of burrowing animals. After the first year the measurements should be made once a year until it is certain that there are 

no significant long-term trends in the radon fluxes. 

2. Gamma-Ray Surveys 

Considerably elevated radon fluxes could occur at isolated locations on a covered tailings pile because of (1) fissures in the material used to stabilize the tailings pile, (2) elevated exhalation 

rates from the underlying tailings material, or (3) variations in 

the thickness of the stabilizing material. Elevated gamma-ray exposure rates could occur at these locations because of the emission 

of gamma-rays from radon daughters that would deposit on the cover 

material. It is quite 1 ikely that at least some of these "hot spots" 

would be missed during a radon flux survey consisting of measurements 

at 30 or so locations. Therefore, it would be desirable to determine 

the locations of these hot spots, and to make flux measurements at 

these locations. 

For the above reasons, gamma-ray surveys should be conducted 

before radon flux measurements are made. The measurements should be 

made using micro-R-meters at an elevation of about 80 to 140 em at 

the grid points of about a 3.5 X 3.5 m grid (Young, et al, 1982). 

This is a considerably denser grid than is likely to be used for the 

radon flux measurements. If an increase in the gamma-ray exposure 

rate is detected at any location, a careful search should be made at 

the surface around that location for elevated contact exposure rates. 

The average exposure rate and the coefficient of variation of the 

exposure rates should then be calculated from the measurements at 

the grid points. Radon flux measurements should be made at locations showing exposure rates greater than three standard deviations 

above the average. 

It may be that the garrrna-ray surveys will detect no signif·icant 

hot spots. If this is found to be the case for the first few tailings piles measured, then the gamma-ray surveys may be discontinued 

for subsequent piles. 

3. Radon Flux Sampling Grid 

According to Leggett, et al. (1978), a parameter should be measured at 30 locations, or at a number of locations equal to 45 times 

the square of the coefficient of variation of the measurements between the sampling locations, whichever is greater. Therefore, in 

addition to the flux measurements made at locations of elevated gammaray exposure rates, measurements should be made at enough grid points 

on a rectangular grid to bring the total number of measurements up 

to at least 30. The coefficient of variation of the measurements 

13 
should then be calculated to determine from Equation (1) whether 

additional measurements should be made. If additional measurements 

are required, they should be made at locations where the original 

measurements have indicated that elevated radon fluxes might be 

present. It may turn out to be cost-effective to make more than 30 

flux measurements initially to insure that it does not turn out to 

be necessary to go back later to make additional measurements. 

4. Time Schedule of Flux Measurements 

A. Year-Long Measurement Series 

The radon flux at any location will fluctuate with time as 

a result of meteorological conditions and the moisture content 

of the emanating material. Since the fluctuations could have a 

seasonal component, radon fluxes should be measured every other 

month throughout at least a year to obtain the annual average. 

If the measurements are being conducted to determine whether 

the cover is performing as designed, then measurements should 

be made once a year after the first year or so until it appears 

certain that the flux is not changing significantly with time. 

Each flux measurement should be made over as long a time 

period as is practical for the measurement techniques being 

used. If charcoal canisters are used, each measurement should 

be made over a period of at least one, and preferably two or 

three days because of the possibility of diurnal and other shortterm variations. It is not practical to sample over much longer time periods than this because radon has only a 3.8 day halflife, so the radon originally collected would mostly decay away 

before measurement if longer sampling periods were used. Also, 

the saturation of the charcoal by moisture and radon during 

longer sampling periods might lower the adsorption efficiency 

of the charcoal. The adsorption efficiency of the charcoal 

canister system used should be determined as a function of 

sampling time by making side-by-side measurements on homogene-· 

ous tailings material whose moisture content and radon flux is 

higher than would be expected for the actual covered tailings 

piles that are to be measured. The measured radon fluxes for 

given time periods should then be compared with fluxes measured 

simultaneously over shorter time periods to determine how long 

a time it takes for the collection efficiency to begin to 

decrease. The measurement periods for tailings piles should be 

kept short compared to this time. 

Radon fluxes will be measured during only a small fraction 

of the total time even with an ambitious measurement program, 

so the measurements should not be made at times when it is expected ~hat the fluxes will depart considerably from average 

values. lherefore, measurements should not be made following a 

14 
heavy rain, when there is ice cover. or during high winds. It 

is also likely that flux measurements should not be made for a 

period of time following the completion of the stabilization of 

the tailings pile. It is probable that the cover material will 

be sprinkled with water following its placement on the tailings 

pile so that it can be packed down more readily. If this is 

done, the radon flux should remain below normal until the cover 

and tailings material dry out enough to approach equilibrium 

moisture conditions. Therefore, flux measurements should be 

made at intervals at a given location on the tailings pile to 

determine when fluxes appear to stop changing systematically 

with time. At that time extensive measurements to determine 

the average flux at a given location from the covered pile may 

be begun. After measurements have been made on a couple of 

piles it may be possible to estimate the time it takes fluxes 

to approach representative values, so that flux measurements 

may be begun following this delay period on subsequent piles. 

However, the time required for the cover material to approach 

equilibrium moisture content could vary greatly with the nature 

of the cover material and climatic cond"itions. 

The number of measur-ements that would be required to determine the average flux at a given locdtion with a precision of 

25% at the 95% confidence level is given by Equation (1). There 

have been some repeated measurements at given locations on tailings piles over extended periods of time. On the average, the 

measurements of Silker and Heasler (1979), Marple and Clements 

(l9l7), and Clements, et al. (1978) show a coefficient of variation with time of 0.4. According to Equation (1), six measurements would be required if the measurements showed this coefficient of variation. The variation would be expected to be different at different locations, so the total number of measurements 

that would be required at any location would have to be determined from the coefficient of variation of the first few measurements at that location. 

It may be that the radon fluxes from a given tailings pile 

will e·ither be so low V1at it will be clear after a few measurements that the net flux will be less than the radon flux stan- dard~ or so high that it will be clear that the average will be 

greater than the standard. Therefore, if the flux measurements 

are being conducted to determine whether the average flux exceeds 

a performance standard, the average and coefficient of variation 

of the flux should be calculated at each sampling location after 

the second (and each subsequent) measurement, and then be used 

to calculate the average and the coefficieflt of variation of 

the flux for the lotal oile. If it is calculated that there is 

either a less than 5% or a greater than 95% probability that 

the average flux will exceed the standard, the flux measurements 

should be discontinued. 

15 
After the flux measurements have been completed, the average and coefficient of variation of the measured fluxes should 

be calculated to determine the probability that the true average 

flux exceeds the standard. If the average flux exceeds the 

standard, and the decision is made to add additional cover material to locations showing fluxes greater than the standard, 

then additional flux measurements should be made at these loca-· 

tions following the addition of the cover material. These measurements should be continued until the probability that the 

average flux from the pile will exceed the standard is calculated 

to be less than 5% or greater than 95%, or until the total number 

of measurements required by Equation (1) is completed. 

It is possible that the measurements over an extended period 

of time will indicate that there is a continued change in the 

flux with time. In that case, if an extrapolation of the data 

indicates that net flux could change from less than to greater 

than the standard (or vice versa) in the future, periodic measurements should be continued, if possible, until it is possible to be reasonably certain whether the final average net 

flux will be greater than the standard. 

The average flux calculated in the above manner will probably be somewhat higher than the true average because sampling 

locations have been selected where elevated fluxes are expected. The coefficient of variation of the measurements might also be 

expected to be greater because of this selection of sampling 

locations, so the number of required sampling locations calculated from Equation (1) would be expected to be greater than 

would be the case if measurements were made only at grid points. 

However, there are significant experimental errors in the mea-· 

surements, and the temporal variations of the radon flux will 

limit the accuracy of the calculated average fluxes. Therefore, 

the bias in the calculated average flux caused by the selection 

of sampling locations should be useful in decreasing the prob-· 

ability that the true average flux will be greater than the 

standard even though the measured average flux is 'less than the 

standard. 

The possibility does exist, however, that tailings piles 

will have a large enough number of small areas of high radon 

flux (hot spots) to cause the average flux, calculated in the 

above manner, to exceed the true average flux by an unacceptable 

amount. Model calculations by Mayer and Zimmerman ( 1981) indicate that a 1.5 em diameter hole that extends completely through 

a 100 em thick cover will increase the average flux over a 150 

cm2 area by a factor of about 30. Therefore, if a large number 

of hot spots are detected, the areas of these hot spots should 

be estimated. Each flux measurement, including the measurements 

at the grid po;nts, should then be weighted according to the 

area it represents when the average flux is calculated. 

16 
B. Two-Month Measurement Series 

It is possible that it will be decided that the requirement 

of a year-long flux measurement series would produce an unacceptable delay in the verification of compliance with a performance 

standard. In that case, the flux measurements should be made 

once a week for two months, even though this shortened measurement schedule would probably result in a decrease in the accuracy 

of the determination of the average flux. The flux measurements 

should not be begun until the radon flux has approached equilibrium values. Repeated measurements at a few locations on at 

least two piles should be used to estimate how long to wait. 

If the measured fluxes change systematically with time, it may 

be necessary to continue the measurements, perhaps with lower 

frequency, until it can be predicted with reasonable certainty 

whether the average flux will be greater than the standard. 

V. Calibration of Radon Flux Measuring Devices 

At the present time there exists no standard calibration facility 

that can be used to calibrate radon flux measuring devices. Such a facility is needed to determine whether these devices are providing accurate 

measurements of radon fluxes. The following paragraphs will describe 

the characteristics of a facility that cou-ld be constructed and used for 

calibrating radon flux measuring devices. It is based upon a design 

proposed by Kearney and Kretz (1981). 

The flux calibration facility should be constructed in an air-tight 

chamber having dimensions of at least 2x2x2 meters. A horizontal, perforated metal plate should be attached to the inside of the chamber about 

30 em above the bottom of the chamber. The plate should extend completely 

across the chamber. A sheet of porous fabric should be laid on the plate 

and then covered by a layer of s~nd or other earthen material having low 

226Ra content. A standard NBS 2 6Ra source should be d·issolved in an 

acid solution and placed in a bubbler in the air space underneath the 

layer of sand. A pump should be used to recirculate the air undern~~th 

the sand bed through the bubbler to transfer the radon produced by Ra 

decay into the air beneath the sand bed~ 26 The air should be bubbled through 

water before being bubbled through the Ra solution to prevent the 

226Ra solution from evaporating away. After· leaving the bubbler the 

humidity of the air may be reduced by passing it through a dessicant. 

Care must be taken to insure that the ·radon becomes well mixed in the 

space beneath the sand bed, but is not forced up through the bed. 

The radon should diffuse up through the sand bed at a constant rate 

to produce a constant flux of radon from the top of the bed. The radon 

emanating from the bed should be removed immediately to prevent radon 

concentrations from increasing above the bed and decreasing the radon 

flux. Therefore, the air above the bed should be circulated through a 

charcoal trap that is cooled with dry ice. The circulation system should 

17 
be designed so that the speed of the air across the surface of the bed 

can be varied and can be measured. 

The radon flux will depend upon the strength of the 226 Ra source and 

the fraction of the radon that decays before it diffuses through the 

bed. Different source strengths can be used to produce varying radon 

fluxes. The fraction of the radon that decays before passing through 

the bed can be calculated from the one-dimensional diffusion equation. 

It can be shown that for a 10 em thick layer of sand, more than 95% of 

the radon should pass through the sand before decaying. 

The radon flux through the sand bed can also be determined by measuring the rate at which radon is collected in the charcoal trap through 

which the air above the bed is being circulated. The quantity of radon 

collected in the charcoal trap can be measured either by gamma-ray spec--

trometry or by heating the trap to desorb the charcoal into a ZnS scintillation cell, and measuring the alpha particle emission rate with a photomultiplier. The charcoal trap should be replaced periodically, and the 

radon concentration measured to determine whether the measured radon 

flux is constant. If it is not, the r·eason for the variation must be 

discovered and eliminated. 

The radon fluxes through the sand bed determined by the above two 

methods should agree within a few percent. If they do not, then the 

reason for the discrepancy should be determined before the chamber is 

used for calibrating the flux measuring devices. 

It is important to insure that the radon flux through the sand bed 

does not vary with location on the bed, so care must be taken to insure 

that the sand has a constant thickness across the bed. The radon f1ux 

should be measured at several times and locations across the bed using 

charcoal cannisters to determine whether there is a spatial or temporal 

variation in the flux. If there is, the variation could, of course, be 

due to inaccuracies in the measurements, but if there is no significant 

variation, then it can be concluded that the flux is constant. If the 

measured flux does vary, the reason for the variation must be discovered 

before the chamber is used for calibrating flux measuring devices. 

It could be that it will not be possible to obtain sufficiently constant fluxes using the chamber described above. In that case, it may be 

possible to obtain constant fluxes by placing layers of well-blended 

mixtures of sand and tailings on the floor of an air-tight chamber. The 

ratio of sand to tailings can be varied to give radon fluxes covering 

the range over whicn the flux measuring devices are expected to be used. 

The flux, and the temporal variation of the flux, can be measured by 

circulating the air above the tailings through a charcoal trap that is 

cooled with dry ice and measuring the rate at which radon is collected 

in the trap. The temporal and spatial variation in the flux from the 

bed would be determined by measuring the flux at different times and 

locations with charcoal cannisters. The objection to this method is 

that the radon flux could not be related to a standard source of radon. 

18 
Once a facility has been constructed that will produce a constant, 

known radon flux, it should be used to determine the rates at which the 

various radon flux measuring devices collect radon as a function of the 

radon flux. The rate of collection should be given by 

C = AF ( 3) 

where c = rate of radon collection (atoms/sec) 

2 A = proportionality constant (em ) 

and F radon flux (atoms/em 2 = . sec). 

It is expected that A will approximately equal the area covered by the 

device. Each device should be used to measure the radon flux over a 

range of (1) radon flux, (2) air speed across the surface of the bed, 

{3) temperature and moisture content of the bed and the air, and (4) pressure to determine the magnitude of the variation of A. If the variation 

is too great, then the device cannot be used to measure radon fluxes 

accurately. However, even if A does not change with air speed in the 

calibration facility, it still may change with wind speed in the field 

because turbulence may cause changes in the radon flux, and the turbulence 

spectrum of the atmosphere w'ill not be duplicated in the calibration 

faci 1 ity. 

19 
References 

Baver, L. D., 1956. Soil Physics, 3rd ed. New York, John Wiley and Sons, 

pp 209-222. 

Bakulin, V. N., 1969. Dependance of Radon Exhalation and Its Concentration in the Soil on Meteorological Conditions (in Russian), Uch. Zap. 

Kirov. Gas. Pedagog. Inst., 30:70-79. 

Bernhardt, D. E., F. B. Jones and R. F. Kaufmann, 1975. Radon Exhalation 

from Uranium Mill Tailings Piles: Description and Verification of the 

Measurement Method, U. s·. Environmental Protection Agency, Technical 

Note ORP/LV-75-7(A). 

Bogoslovskaya, I. N., A. G. Grammakov, A. P. Kirkov and P. N. Tverskov, 

1932. Report of the work of the Kavgolovo Experimental-Methodical Party 

in the Year 1931, Izu. Vses. Geol-Razved. Ob"yed 51:1283-1293. 

Caplan, P. E., 1972. Calibration of Air Sampling Instruments I -General 

Considerations and Flow Metering, in Air Sampling Instruments, American 

Conference of Governmental Industrial Hygienists, pp. H-1 to H-8. 

Clemer1ts, W. E., S. Garr, and M. L. Marple, 1973. Uranium Mill Tailings 

Piles as Sources of Atmospheric Radon-222, Natural Radiation Environment 

III, pp 1559-1583. 

Clements, W. E. and M. H. Wilkening, 1974. Atmospheric Pressure Effects 

on 

222 Rn Transport Across the Earth-air Interface, Journal of Geophys;cal 

Research, 79:5025-5029. 

Colle', R., R. J. Rubin, L. I. Khab, J. M. R. Hutchinson, 1981. Radon 

Transport Through and Exhalation from Building Materials, NBS Technical 

Note 1139. 

Countess, R. J., 1977. Measurements of 222 Rn Flux with Charcoal Canisters, 

Workshop on Methods for Measuring Radiation in and Around Uranium Mills, 

Albuquerque, New Mexico, pp. 139-147. 

Duwe, M. F., 1976. The Diurnal Variation in Radon 

due to Atmospheric Pressure Change and Turbulence. 

of Wisconsin - Madison. 

Flux from the Soil 

PhD Thesis, University 

Ford, Bacon and Davis Utah, Inc., 1981. Engineering Assessment of Inactive 

Uranium Mill Tailings. 

(a) Durango, Colorado, DOE/UMT 103, FBDU-360-06 

(b) Shiprock, New Mexico, DOE/UMT 104, FBDU-360-02 

(c) Grand Junction, Colorado, DOE/UMT 105, FBDU-360-09 

(d) Riverton, Wyoming, DOE/UMT 106, FBDU-360-19 

20 
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· x!1-J ·,at. i c; Fr·.-:.1: Ph..:;:;r '1 ::Jte Gyp~~wr: P·! 1es a.r,d llc.:tc'l:i ve 1..iran :~.,,·: !il-i , i ~- rl i lings 

ro: i,?·,, ~qJ\vt Ei-'li·-5/0/5-n-004, U.S. r:nv~ronmer·:tal Pnrt.e,: 1·.-i,_::: i1g•.'r.C_r', 

~.Ft.e:·;·: f:.r,v·irn!l'~cr:lol Ri:;Jiation f":t·.:ilit_•_:, t•lcrltgc-~nHy, A-i.:.lJit-~:c. 

i::,:<·c-'1 1 H, -::Jf1~1 ro,1, rlorbert, 'i97C. Tracing f>.tmc>Sph2l H: Edc:y r"::;;;~ f\·:'lnsfer 

~,j_. r~·;c'i:li,-; ':.f r~::li:,rr<rl f(;1dir.3.cl ivity, ~:our no~ of (leoph:y-.;:. ic.:1-i ~-(,:· .. ec.rch" 

rJ: 2('9-1-2'29?. 

l<t3.·~'!</, ~·- i:·. 0.JH.i r·'. LL i(r,_:t:!, l98l. Pacinn i;bx ML:::tsurer;rePt~:~ ~·. 

:.~\i~ration fari1ily. lwPnty-Sixth Annual Meetinq of the ~:c1l+h P~ijSlCS 

'-:-.-;-_i';-~~y, Lc ... i-::vi: 1 t"!, Ke.,tucky. 

-.·; :. >::>~;'-:i \~. '- ., J .. [-_, t>lrson, 1':. E. [:ungey, N. [i, Ki·et:~, ,L r.'. 

~.:r i·;Li'>'W·, H. fi. f•1,-hTic~ni, ~~-fl. R<lYliO, C, \ .. ~);ltJau, 'l91lC. r:a,J:;n ~~o--iE''.J'~l: 

c;n:-! t:·-!sp .:;r':;ion -r··-o;,~ :Jri C:per1 FH Utcmiw~ M~nt:<, NlJRC_G/C:R-1~:.;::-J 

\c:r 't<il" f(2qi1l :~U!r'J Com11- i ~;s ic·n. 

., 

• 0 

Krarer, h. ~., C. W. Schraeder, ar1d R. D. ~vans, 1964. ~rbsurrments of 

tire E'fL:Lt~ cf ,~ti1'0Spherlc Variab'lcs on Radon-222 Flux :1nJ Sojl :-;a<; C('n--

rentr~t1ors. T~e Natt1ral Radl6tior E1viron~Ent, pp 1Yl-215. 

[.f~\r:ett, i~. ~~·.,H. W. [h~:kst:.n and r. !". HC.J'lt!Ofld, H7fL /• S'ti'EI~-T,i(.(1.1 

~-·'.-_ct~~'dOl:JSJ;t fL'lr Rttd-iolr:.~ical ~ur·vE:yirrq, ]At;\ ~~ymposi~Hil ur; _-\ch;:,'.<·,.,_.; in 

:-:.-~~!·ioJ, i(w Prct.r;ct i')n ~tnr:itorinq, Jr-\Ei\·5i·~ .. 2:_!Y/ :O~L 
Macbeth, P. J., C. M. Jensen, V. C. Rogers and R. F. Overmeyer, 1978. 

Laboratory Research on Tailings Stabilization Methods and Their Effectiveness in Radiation Containment, Department of Energy report GJT-21. 

Marple, M. L. and Clements, 1977. Measurements of Radon-222 Flux from 

Inactive Uranium Mill Tailings Piles, ERDA Report LA-6898-PR, Los Alamos 

Scientific Laboratory, NTIS. 

Mayer, D. W. and D. A. Zimmerman, 1981. Radon Diffusion Through Uranium 

Mill Tailings and Cover Defects, NUREG/CR-2457, PNL-4063. 

Megumi, K. and T. Mamuro, 1972. A Method for Measuring Radon and Thoren 

Exhalation from the Ground, Journal of Geophysical Research, 77:3052-

3056. 

Megumi, K. and T. Mamuro, 1973. Radon and Thoron Exhalation from the 

Ground, Journal of Geophysical Research, 78:3357-3360. 

Momeni, M. H., W. E. Kisieleski, S. Tyler, A. Zielen, Y. C. Yuan, and J. 

Roberts, 1979. Radiological Impact of Uranium Tailings and Alternatives 

for their Management, presented at the Health Physics Society Twelfth 

Midyear Topical Symposium on Low Level Radioactive Waste Management, 

February ll, 1979. 

Pearson, J. E. and G. E. Jones, 1965. Emanation of Radon-222 from Soils 

and its Use as a Tracer, Journal of Geophysical Research, 70:5279-5290. 

Pearson, J. E. and G. E. Jones, 1966. Soil Concentrations of "Emanating 

Radium-226" and the Emanation of Radon-222 from Soils and Plants, Tellus 

18:655-662. 

Rogers, V., R. F. Overmeyer, C. M. Jensen and E. Canon, 1979. Characterization of Uranium Tailings Cover Material for Radon Flux Reduction, prepared by Argonne National Laboratory for Ford, Bacon and Davis Utah, 

Inc., FBONI-218-l. 

Silker, W. B., and P. G. Heasler, 1979. Diffusion and Exhalation of 

Radon from Uranium Tailings, NUREG/CR-1138, PNL-3207. 

Silker, W. B. and P. G. Heasler, 1979. Diffusion and Exhalation of Radon 

from Uranium Tailings, NUREG/CR-1138, PNL-3207. 

Styra, B. I., 1968. Se1fpurging of the Atmosphere of Radioactive Contamination. Hydrometeorological publication, Leningrad, English translation 

by M. Lang. 

Strong, K. P. and D. M. Levins, 1982. Effect of Moisture Content on 

Radon Emanation from Uranium Ore and Tailings, Health Physics, 42:27-32. 

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review, in Natural Radiation Environment III, Vol. 1, 

22 

A supplementary 

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Release from Open Pit Uranium Mining, NUREG/CR-2407, PNL-4071. 

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Measurements in Widely Separated Regions, The Natural Radiation Environment II, Proceedings of the Second International Symposium on the Natural 

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Workshop on Methods for Measuring Radiation in and Around Uranium Mills, 

Albuquerque, New Mexico, May 23-26, 1977, pp. 131-138. 

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NRC FO"M 335 U.S. NUCLEAR REGULATORY CCNMISSION 

1. REPORT NUMBEFIIA"''~d by DOC} 

17·771 NUREG/CR-3166 

BIBLIOGRAPHIC DATA SHEET PNL-4597 

4. TITLE AND SUBTITLE /AddV_,_ No., iffiPProprN•I z.tu-bllltk} 

Recommended Procedures for Measuring Radon Fl uxes from 

Di sposa 1 Sites of Residual Radioactive Materials 1 RECIPIENT'S ACCESSION NO. 

7. AUTHOR IS) &. DATE REPORT COMPLEJC.O 

J.A. Young, v.w. Thomas, and P.O. Jackson MONTH ~!lEA" 

Februa rv 1983 . 

9. PERFORMING ORGANIZATION NAME AND MAILING ADDRESS (lrJChlde Zip Co*) DATE REPORT ISSUED 

MONTH 1rm Pacific Northwest Laboratory March 

Richland, WA 99352 6. fL•- bl.nt) 

8. a..- bl.nk) 

12. SPONSORING ORGANIZATION NAME AND MAILING ADDRESS (Inch/de Zip Co*) 10. PROJECTfTASKIWORK UNIT NO. Division of Waste Management 

Off.ice of Nuclear Material Safety and Safeguards 11. CONTRACT NO. US Nuclear Regulatory Commission 

Washington, DC 20555 FIN 82216 

1"£"100 COVl,.EO UncJu,r,. IU,;rJ 

. .. 13. TYPE OF REPORT 

Fi na 1 Report Sept., 1980 to March, 1983 

15. SUPPLEMENTARY NOTES 14. IU-I:Jir~ttl 

16. ABSTRACT QOO wonlr or ltu} 

This report recommends instrumentation and methods '!'tlitable for measuring radon 

fluxes emanating from covered dis posa 1 sites of residual radioactive materials such 

as uranium mill tailings. Problems of spatial and tempera 1 variations in radon 

flux are discussed and the advantages Jnd disadvantages of several instruments are 

examined. A year-long measurement program and a two month measurement methodology 

are then presented based on the inherent difficulties of measuring average radon 

flux over a cover using the recommended inStrumentation. 

17. KEY WORDS AND DOCUMENT ANALYStS.· 17L DESCRIPTORS 

17b. IDENTIFIERS/OPEN<NDEO TERMS 

18. AVAtLASIL.ITY STATEMENT 10. fn'f(RITY ~fffl mo• "P"rl 21. NO. OF PAGES 

nc ass1 1e 

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