&ER&
United Slates
Environmental Protection
Agency
Office of Radiation Programs
Eastern Environmental
Radiation Facility
1890 Federal Drive
Montgomery, AL 36109
EPA 520/5-87-005
June 1987
Radiation
EERF Standard Operating
Procedures for Rn-222
Measurement Using Charcoal
Canisters
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EPA 520/5-87-005
EERF STANDARD OPERATING PROCEDURES FOR
RADON-222 MEASUREMENT USING CHARCOAL CANISTERS
David J. Gray
Sam T. Wtndham
March 1987
U.S. Environmental Protection Agency
Office of Radiation Programs
Eastern Environmental Radiation Facility
1890 Federal Drive
Montgomery, Alabama 36109
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EERF Standard Operating Procedures for
Radon-222 Measurement Using Charcoal Canisters
I. Introduction
Activated charcoal has a large affinity for several gases and vapors
including radon-222 (hereafter referred to as radon). Radon Is sorbed
onto the charcoal grains and decays to several participate decay products:
radium A (polonium-218); radium B (lead-214); radium C (blsmuth-214);
radiunrC1 (polonlum-214); and radium 0 (lead-210). Radon concentration Is
determined by counting the gamna ray emissions of both lead-214 (295 KeY
and 352 KeY) and bismuth-214 (609 KeY). This Is possible due to the
relatively short half-life of these progeny. Within 3 hours the progeny
are In equilibrium with radon-222.
The passive nature of activated charcoal allows both adsorption and
desorption, and, in addition, the adsorbed radon undergoes radioactive
decay during the exposure period. Therefore, the canister cannot
uniformly Integrate over the entire exposure period. However, the
canisters can be calibrated to yield precise results for radon
concentrations In structures during the deployment period of 48 hours used
by the U.S. Environmental Protection Agency (EPA).
The charcoal adsorption method has been reviewed extensively by Cohen
(Co83, Co86), Prichard (Pr85), and George (Ge84). The EPA's canister and
analysis technique most closely resemble George's work, differing only In
calibration aspects.
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II. Materials and Equipment
A. Charcoal Canister
The passive radon charcoal canister used by the EPA consists of the
following materials: (1) 8 ounce metal can with I1d (4 Inch diameter by
1 1/8 Inch deep); (2) 70 ^ 1 grams of 6 X 16 mesh activated charcoal;
(3) metal screen, with an openness of at least 30 to SO percent;
(4) removable, Internally expanding retaining ring; (5) pad material
attached to the Inner surface of the lid; and (6) a 13 Inch strip of
pliant vinyl tape. The materials are assembled as seen In Figure 1.
The activated charcoal must have low radioactivity content.
Specifically, gamma emitters, except for natural potasslum-40, must be
less than 0.1 plcocurles per gram.
B. Counting System
The following components make up the counting system used by the
EPA's Eastern Environmental Radiation Facility: (1) 3' by 3"
sodium-Iodide detector and photomultlpller tube Inside counting shield;
(2) high voltage power supply; (3) pre-amplifier and amplifier; (4) single
channel analyzer and sealer; (5) timer; (6) time of day clock; and
(7) printer.
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Pad attached to lid to retain
screen during shipping
X
Internal expanding
stainless steel
retainer ring
8 ounce metal can
13" strip of vinyl tape
Stainless steel screen,
30-50 percent open
70 + 1 grams of 6 i 16 mesh charcoal
FIGURE 1
Charcoal canister assembly
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Four sodium fodlde detectors are served by a single high voltage
power supply, timer, printer, and time of day clock. Each detector has
Its own pre-ampllfler, amplifier-single channel analyzer, and sealer. The
four detectors are arranged together Inside a shield that has steel walls
8 Inches thick. Within the shield the detectors are separated from each
other by 4 Inches of lead. A wooden jig Is used on each detector to
assure consistent counting geometry for the canisters on the detector.
The arrangement of detectors In the shield and the electronics are shown
In Figures 2 and 3.
The counting system is operated in the single channel mode with a
lower discriminator setting of 270 KeV and an upper discriminator setting
of 720 KeV. All counts in this region are summed during the counting
period. A multi-channel analyzer is used once a week to assure there has
been no shift of the peaks In the region of interest.
C. Radon Calibration Chamber
The EERF uses 2 radon calibration chambers to expose charcoal
canisters and* other instruments to known concentrations of radon and radon
decay products in controlled environmental conditions. Radium-226 sources
are used to provide radon which 1s continuously flowed through the
chambers. In the chamber, controlled conditions include relative humidity
(10 to 90 percent), temperature (0* to 40*C), condensation nuclei (10 to
106/ml), radon concentration (10 to 1,000 plcocuries per liter
(pCI/liter), and radon decay product concentration or working level (WL)
(0.01 to 5 WL).
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FIGURE 2
Four detectors 1n counting shield
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FIGURE 3
Two shields with electronics
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The temperature, tumidity, radon concentration, radon decay product
concentration, and condensation nuclei concentration are monitored
continuously and printed out each hour. Radon concentrations are
monitored using a 0.5 liter flow through scintillation cell and decay
product concentrations are monitored by counting, with a surface barrier
detector, the alpha activity from decay products collected on a filter.
Grab samples in conjunction with the hourly printouts are used to
determine radon and decay product concentrations in the chambers. The
grab samples, which are done In conformance with recently published EPA
procedures (EPA86), are used to calibrate the hourly printouts.
0. Standard and Background Canisters
Counting system performance Is determined daily by counting standard
canisters containing known radioactivity and background canisters. The
standard canisters were made by the quality assurance group at the EERF In
the following manner: (1) a known activity of about 20.5 nd, liquid
radium-226 was slurried into the 70 grams of charcoal in a canister with
the retainer screen removed; (2) this was heated to dry all liquid from
the charcoal; (3) the canister was sealed by soldering a galvinized metal
disc in the can where the screen normally is located; (4) the lid was
placed on the canister and secured with tape; and (5) the standard was
stored for thirty days to allow secular equilibrium to be reached between
the radium, the radon, and the progeny. Standard and background canisters
were prepared for each crystal and are counted every morning to establish
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a dally counting efficiency for each detector systea. The counting
efficiency Is determined by counting the standard and background canisters
each for 10 minutes. The background count Is subtracted from the standard
count to get the net count. This Is divided by the tine, 10 mfnutes, to
get net counts per minute (CPM). By dividing the net CPU by the known
activity (pd) of the standard the efficiency (CPM/pCI) of the detector
for that day 1s determined.
E. Scales
Digital scales are used to weigh individual canisters both before
shipment to the user and upon receipt after exposure. This weight
difference, which relates to moisture gain or humidity, Is an integral
part of the calculation of radon concentration and will be explained In
greater detail in the next section. Canisters are weighed to 0.1 gram
accuracy.
8
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III. Laboratory Methods
A. Canister Preparation
Calibrations are run on representative samples of canisters from each
new batch from a supplier. As required by the EPA purchase contract, the
supplier identifies each batch by the color of the vinyl tape used to seal
the lid. Gamma emitter content of the charocal is also checked for each
batch to make sure no contaminated charcoal 1s being used.
Each canister Is given an individual serial number. This number Is
printed on the data label attached to the top of each canister. Once this
label is attached, the canister is weighed and the weight 1s written on
the label and is automatically entered into the EERF computer for that
respective canister serial number. The canister Is now ready to use for
calibration runs or In a home for a radon measurement.
B. Calibration
The response of charcoal canisters depends on the length of time the
canister is exposed and on the amount of water gained during the exposure.
This is because the charcoal has a strong tendency to adsorb water from
air. For this reason the canister calibration Is a two step process
designed to adjust for both water gain and exposure time. The following
steps are used to calibrate canisters:
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1. Chamber Preparation
The charcoal canisters are calibrated to three timidity ranges (low,
medium, and high) over a period of one to six days. Low, medium, and high
humidity correspond approximately to 20, 50, and 80 percent humidity. The
radon concentration In the chamber 1s kept as constant as possible during
the three runs. The first step of this process, therefore, entails
stabilizing the chamber at the desired condition.
2. Canister Exposure Sequence
When the chamber Is stabilized, a set of 30 canisters Is put Into the
chamber and exposed In the following manner: a group of five each for 1,
2, 3, 4, 5, and 6 days, respectively. The canisters are opened Inside the
chamber and the exact start times are recorded. This exposure sequence Is
repeated twice more, once at each of the other two hualditles, to complete
the calibration run.
3. Removal and Counting
At the end of each 1 day period specified above, a group of 5
canisters 1s removed for counting. The lids are placed on the canister
while still Inside the chamber and the canisters are reooved, taped, and
the exact time Is recorded. The canisters are allowed to sit for at least
3 hours to allow progeny to equilibrate with the radon before counting.
10
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Each canister 1s counted for ten minutes on a sodium-Iodide detectors
described previously. The count time and detector number are recorded so
that the efficiency of that detector, from previous counting of standard
and background, can be Incorporated In the calculation of calibration
factors. After counting, the canisters are weighed and the weight
difference Is recorded.
4. Calculation of Calibration Factors
A calibration factor 1s calculated for each canister using the
following equation:
CF _ NET CPU (Equation 1) (Ge84)
(Ts) (E) (RN) (OF)
where
CF = Calibration factor, radon adsorption rate (1/mln),
NET CPH = Gross CPM for that canister - background CPM for that
detector for that day,
T = Exposure time of the canister (minutes),
E = Detector efficiency for the appropriate detector (CPM/pCI),
RN = Radon concentration 1n the chamber for the exposure period
(pCI/llter),
OF = Decay factor from the midpoint of exposure to the time of
counting, which Is calculated from
.693t .693t
DF = e' T » i«*-\ or e
'w» R« (min) c 5501 mln
i/t n
where t = time 1n minutes from midpoint of exposure to the start of
counting.
11
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5. Generation of Calibration Curves
Calibration factors as derived from the equation above are used to
generate two tables and two curves. The first table, Table 1, relates
calibration factor to weight gain (water) for the canisters for a 2 day
exposure, the time used by EPA for Its surveys (see IV 0). Data 1n this
table are plotted to generate Figure 4. The second table, Table 2,
relates exposure time to adjustment factors for 20, 50, and 80 percent
humidity. The adjustment factor Is used to modify the calibration factor
for exposure times different from the desired 2 day exposure time. If a
canister Is exposed for exactly 2 days, the adjustment factor Is 1. This
1s explained In more detail In III C 5. Data In this table are plotted to
generate Figure 5.
Figures 4 and 5 are typical calibration data that were developed for
a particular batch of canisters from a supplier. New calibration data are
developed and used with each different lot of canisters.
C. Calculation of Radon 1n an Exposed Canister
Equation 1 above nay be rearranged to solve for the radon
concentration If the calibration factor Is known. This equation will be
RN , MET CPH (Equation 2)
(Ts) (E) (CF) (DF)
12
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where
RN » Radon concentration In pCI/llter,
NET CPM = Gross CPM for the canister - background CPN for that
detector for that day,
T * = Canister exposure time (minutes),
E = Detector efficiency (CPM/pCI),
CF = Calibration factor, and
OF •= Decay factor from the midpoint of exposure to the start of
counting.
Table 1
Water Gain Versus Calibration
Factors For a 2 Day Exposure
Percent Humidity Water Gain (g) CF (I1ter/m1n)
20
20
20
20
20
50
50
50
50
50
80
80
80
80
80
0.0
0.0
0.0
0.0
0.0
1.7
1.8
1.9
1.8
1.8
7.7
7.5
7.7
7.9
7.9
0.105
0.101
0.105
0.110
0.107
0.098
0.094
0.097
0.102
0.096
0.077
0.082
0.076
0.076
0.078
13
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Table 2
Exposure Time Versus Adjustment Factors
for Low. Medium, and High Humidity
Time of Exposure
(Hours)
24
24
24
24
24
48
48
48
48
48
72
72
72
72
72
96
96
96
96
96
120
120
120
120
120
144
144
144
144
Adjustment Factors
20 Percent
0.137
0.143
0.141
0.135
0.138
0.107
0.110
0.105
0.101
0.105
0.087
0.091
0.088
0.083
0.085
0.074
0.080
0.075
0.074
0.075
0.070
0.073
0.071
0.069
0.071
0.064
0.068
0.064
0.062
50 Percent
0.132
0.137
0.132
0.126
0.127
0.096
0.102
0.097
0.094
0.098
0.075
0.079
0.075
0.073
0.075
0.058
0.062
0.059
0.057
0.060
0.051
0.054
0.051
0.050
0.052
0.045
0.047
0.047
0.044
(llter/mln)
80 Percent
0.116
0.125
0.118
0.117
0.118
0.077
0.082
0.076
0.076
0.078
0.048
0.051
0.051
0.046
0.049
0.035
0.034
0.033
0.033
0.034
0.023
0.025
0.024
0.023
0.023
0.018
0.019
0.016
0.018
14
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FIGURE 4. WATER GAIN VERSUS CALIBRATION FACTORS (CF)
FOR A TWO DAY EXPOSURE
-«- --•••••••••••••
:&::::::»......! ••
*********
•••••••••••••••••••••••••••••••••••••a***
--•«••••••••»«••••••••••••*••••••••••*
»•-_. -*•••*•«••••••••«••••••••••••
•••*••••••-. ^•••••••••••••••••••••
.04-
.02'
I
0
2.0
4.0
6.0
8.0
I
10.0
12.0
14.0
160
1
18.0
Water Gain (g)
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Figure 5. EXPOSURE TIME VERSUS ADJUSTMENT FACTORS (AF)
FOR LOW, MEDIUM, AND HIGH HUMIDITY
.14
.12
.10
.06
.06
.04
.02
10 20 30 40 50 60 70 80 90 100 110 120 130 140 150
Exposure Time (Hours)
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The following steps are taken to analyze the canister and calculate
the radon concentration to which a canister has been exposed:
1. Count the standard canister on the detector to be used.
Calculate the efficiency (E) for that detector 1n CPM/pCI as In section
II-D. This efficiency Is used for all counting done on that detector for
that day.
2. Count the background canister on the detector. This background
count Is used for all counting done on that detector for that day.
3. Weigh the canister to be analyzed. This weight gain In grams of
water during the exposure period Is referred to as (g) In Table 1 and
Figure 4.
4. Use the water gain (g) on the X-axis on Figure 4 to obtain an
Initial CF from the Y-axis.
5. If an exposure period other than 48 hours was used, this Initial
CF must be adjusted to reflect the actual exposure time for the canister.
This Is done by using the water gain to select the appropriate humidity
curve on Figure 5. The correct humidity curve Is selected based on the
following criteria:
If (g) Is Use Curve for
less than 1.0 g 20 percent
1.0 g to 4.0 g 50 percent
greater than 4.0 g 80 percent
17
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Using the correct water gain on the X-axis and relative humidity
curve on Figure 5, an adjustment factor (AF) Is selected from the Y-axis
and used to adjust the Initial CF (obtained In step 4 above) for the
exposure time. This Is done as follows:
Final CF used in Eq. 2 = Initial CF X AF for actual exposure time
AF for 2 day (48 hr) exposure time
From this it is seen that If the actual exposure time 1s 48 hours the
AF becomes 1.0 and the initial CF Is actually the 'CF used In Equation 2.
6. The decay factor (OF) Is used to correct for radiological decay
between exposure and counting. It Is calculated from the midpoint of
exposure to the start of counting using the formula
.693t
OF
= 6 ^1/2 ^or rad°n
where t is the tine from midpoint of exposure to the start of counting and
T. iy Is the half-life of radon.
EXAMPLE CALCULATION
To calculate the concentration of radon in a canister we use
Equation 2,
RM= NET CPH
(Ts) (E) (CF) (OF)
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The data gfven for this example calculation are the following:
Weight Out • 158.7 g
Weight In » 161.1 g
Exposure Period = 12-29-86 at 1052 CST to
01-01-87 at 0950 CST
Gross Counts = 2,942 in 10 minutes
Background Counts = 721 in 10 minutes
Standard Counts = 58,423 in 10 minutes for a 20,549 pCI source
From these data, we first determine that
Net CPM =
- 721 = 222 CPM
10 min.
T = 70 hours, 58 minutes = 4258 minutes, and
E = (58.423 - 72D/10 minutes = 0.281 CPM/pCi.
20,549 pCi
To determine the calibration factor (CF), we must refer to the equation
CF , Initial CF X AF for exposure time
AF for 2 day (48 hours)
and use the weight gain in our calculations. In this example, the weight
gain during exposure was 2.4 g (161.1 g - 158.7 g). From Figure 4, we
find that the initial CF for 2.4 g - 0.094; and, according to Figure 5,
19
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a 2.4 9 weight gain requires the use of the curve for SO percent
humidity. Since a 2.4 g weight gain of 50 percent humidity results 1n an
AF for the actual exposure time (~ 71 hours) of 0.080 and an AT for 48
hours of 0.098, the final CF Is 0.077, as calculated by
final CF = 0.094 X °'080 = 0.077 .
0.098
The decay factor for Equation 2 Is calculated by
.693t
DF • •• ^
where t = midpoint of exposure time to start of counting time,
2
= 6,441 minutes,
and Tj ,2 of radon = 3.82 days or 5,501 minutes. The decay factor then
Is calculated by
(.693) (6,441)
OF = e~ »
5,501
= 0.444.
20
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The final radon concentration Is calculated by substituting the above
values Into Equation 2 as follows:
222
RN =
(4258) (0.281) (0.077) (0.444)
= 5.4 pCi/liter.
The 2-sigma counting error Is calculated as follows:
2o.error = 2 YGross counts * Background Counts
Gross counts - Background Counts
2o error = 2 V2.942 * 721 §
2,942 - 721
= .054.
= 5.4 percent.
Therefore, the radon concentration was 5.4 pC1/liter ^ 5.4 percent.
D. Calculation of Minimum Detectable Activity
The minimum detectable activity (MDA) for measuring radon using
charcoal canisters 1s a function of the background counting rate of the
counter system and the counting time (A163). The MDA at the 3-sigma
significance level Is given by
HDA . 3 X V
BKG Count Time
21
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where
MDA = MOA as function of counts above background,
BKG Count = Total background counts, and
BKG Count Time = Counting time of background.
For the ECRF counting system, this calculates as
r750"
MDA (CPU) = 3 X ,
10
= 8.2 counts per minute.
This may be converted to activity of radon In pd/llter by assuming
exposure conditions. For our desired exposure conditions, this calculates
as follows:
Assumed conditions:
Exposure time = 2 days (48 hours)
Relative humidity - 50 percent (2 gram water gain)
Time in shipment = 3 days (4,320 minutes)
Counter efficiency = 0.28 CPM/pCi
MDA (CPM) =8.2 (from above)
MDA (CPH)
MOA (pd/llter) = (Exposure Tfme) (E) (CF) (DF)
8.2
(2.880) (0.28) (.098) (.48)
= 0.22 pd/llter
Since assumed conditions are not always met, In EERF data reports the MDA
Is conservatively reported as less than 0.5 pC1/liter.
22
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E. Quality Assurance Procedures
The EERF radon calibration chambers are the principal source of
quality assurance exposures for charcoal canisters. After the Initial
calibration run on each new batch of canisters from a supplier, periodic
checks are made on randomly selected canisters to assure no deviation.
Reliability of the EERF calibration chambers Is assured through
several programs. As described previously, the chamber Is monitored
continuously while In operation. Also, dally checks on the radon and
t
radon decay product concentrations are made using grab sampling
techniques. These same techniques are used by the EERF In national and
International measurement cross-check programs. The EERF participates In
these programs every time they are offered, usually several times per
year. The EERF also sends groups of Us canisters to operators of other
radon calibration chambers for blind exposures as verification checks.
As part of the EERF's participation 1n the state radon survey
program, we request that the participating states expose duplicate
canisters and return them to the EERF for routine processing. This Is
usually done In 5 percent of the homes surveyed. The EERF also requests
that the states submit blank canisters back to the EERF for analysis.
These are sent In by each state at a rate of approximately 2 canisters
per week.
23
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The sodium Iodide detectors and counting systems used for the
analysis of canisters are calibrated dally using standard sources
described 1n section II-D. The standard count for each detector system
each day Is entered Into a computer maintained control chart (Ro65). If
the dally standard count exceeds the 2 slgma variation of the average of
all previous counts for that system, the system Is not used for counting
until the cau'se of the excessive variation Is determined. The same type
analysis Is also performed dally for a background canister on each system.
In actual field use the coefficient of variation of a canister should
not exceed 10 percent at a radon concentration of 4 pCI/llter or greater.
This precision Is monitored using duplicate canisters (EPA86).
24
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IY. Survey Methods
A. Shipping of Canisters
Canisters are prepared for use as described In section III-A. After
preparation they are Individually boxed and the Individual boxes are
packed Into a shipping case, usually 150 canisters per case. These are
shipped to the users through normal commercial carriers. An Individual
canister In its box may be mailed to a user. Prepaid labels are used to
ship the Individual boxes to the user and a prepaid label Is provided to
return the canister from the user to the EERF. Each Individual box has a
gummed flap for sealing the box prior to shipment.
B. Deployment
The charcoal canisters should be used as directed In the Interim
Indoor Radon and Radon Decay Product Measurement Protocols,
EPA 520/1-86-04, April 1986. The protocols specify house conditions at
the time of measurement, provide Instructions on selecting the location
In the house at which to make the measurement, and suggest how to
interpretation of results. Copies of the Interim Indoor Radon and Radon
Decay Product Measurement Protocol may be obtained by written request to
either of the following addresses:
U.S. Environmental Protection Agency Eastern Environmental
Office of Radiation Programs (ANR-458) Radiation Facility
401 M Street, S.W. 1890 Federal Drive
Washington, DC 20460 Montgomery, AL 36109
25
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Hurt te rim 9* Oortoel
Mem Orte MTO that ft* It ho«r» before wd d*rlof the >-«v MlSoroBMl period:
• HndoM end enternil doors art Uft closed, tuoot for oorwl entry oaf ortt,
• ran or wettlatlM sjrstees that m wui* ilr. toe* M •UU fiat. w« aot eetrete*.
If jrour bouse has I botaMat. place ttt ctnltUr i^vtert li tin liM««t. iict»t t» •
|tri|i. rwt nlltr. or crtvl ifttt. If i««r kewu tow «et *•«• • b*it«tiit. »1tM tk* cMlitor
li «V rev w UM loMtt floor of tta ten*, tietpt 1o t ttUroca. kluhtn. or porck.
Mttdi tt» MltcUd room. U» cmliUr ikouK Mt to lo o locttloo frtqytntlji MpoiH U
Mtknblt drifU of on open door, vlnden. flrtplKt. etc. Ao unlitor «ho«U tt ti^ot»d to «1r
•toolo brtttht. It thovltf to p1*co« oo o Ublt or thtlf ot looit t foot obon ttt floor MM
itald bt In optfl tfr. not In o clout. o>uor, cupbo*r4, ott.
The unftttr should be opened ind eiyoted U the olr for t full dk/f (41 hours) «»d the*
returned towdliUljr for procftslng. foil* the HOCCDUK btloi for optntng wd nttiMn( Ut
ckircpsl c«Miter. Do not open the coilstor to begin U* octsvreocnt If jov annot end the
to f dfys.
MKIDUU
1. hone the tept fro* oround U« ceilttcr. Sin the Upe to retool the cutster ot the end of
the BiiBrcotrt.
t. Hoove OH lid fr» the unlsur. Piece the lottr holf of the twister, wltt the screen si*
op lottft the open olr, on o Uble or shelf to the roc* chosen occordlof to the ibOM
listrvctloM.
L Mil to the tUrt fete end Hot oo the label on the uoliUr 114.
4. After 2 foil d»/i (48 Hours), replace the lid on the unfitcr ind rtMil It *1U the Upe.
I. fill In tht step diU end tloe on tte libel. Tkls Is tirj totwrUnt. Mso. pleise fill lo
V* Inforttttlon requested (To Be tacleud B/ Occvpint) OB the other side of this sheet.
I. Floce the canlsUr end this sheet lo tht bo* provided. Scol the boi is shorn beloo end plice
the iddreiwd. posuge-psld libel « the be*.
I. Ml the boi «tthlo 1 diy of reieilloi the emitter, fc poiUoo Is roojilrod.
FIGURE 6
Instruction sheet
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C. Forms
A combination data-Information form 1s shipped with each canister.
The Information side of the form contains detailed Instructions for use
and return of the canister. This form 1s shown In Figure 6. The other
side of the form consists of blanks to be completed by the homeowner and
the government agencies conducting the study. This data form Is shown In
Figure 7. Accurate and complete answers In the blanks are very Important.
0. Time Restrictions
The following time restrictions, In regard to exposure time and the
time In transit during return of the canister, are used 1n the EERF
programs. The exposure time for the canister must not be less than 24
hours (1 day) nor longer than 144 hours (6 days). The desired exposure
time Is 48 hours (2 days). The time delay In returning the canister to
the EERF for processing should be as short as possible to avoid excessive
decay. All canisters received at the EERF are counted, regardless of the
delay time. If the 3 slgma counting error 1s less than 100 percent, the
results are calculated. If the 3 slgma counting error Is greater than 100
percent, the canister Is not calculated.
E. Reporting
Usually, all canisters received at the EERF are counted on the day
they are received. The EERF reports results from canisters processed each
two weeks. The report contains data for the canisters received during the
27
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canna » KOTO?
kit Ml ttM JM lUltH Ml
f Urt *tt / / TIM
IMMt
HM
m
U8 teU / /
Q*
M III
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t. T»t of bv1141»t In «ti«di •Nivrioent MS Mdi: Q |1*«1« fully tarn
Q HUI-f«
U; building Q builntu Q Khoel Q othtr
I. Poor of kwlldlfig i**r* •"wcwnt nt Hdt: Q biumit Q ftrtl Hoar
MC«rv4 floor or tbmt
fMll/ roM Q ll»1ng roM
* othtr
4. IOCB t* «Meh HiiureHnt Hi Hdt: Q btdreoB Q_f
Q uiffnlihctf tatncnt Q offlci Q cl»iveo J]
I. Vert tiUrler doort tnd wtadoas Httljr oota or closttf Airing Ktuirnntt
Q Hottl/ optn Q Hoitlj cloud
intt:
•ouu I.D. Code
ttologk Region Co*
FOR GOrUNCn OH
bnliter
(On unliUr 1tb*l)
kit iKtlvtd
(M HI
BlU Counted
Dttector liatar
Mlgkt Ait
tnUrtd tar
• d jrr
lr«u Ce»»U
thlgkt I»
R
Ckcctod tgr.
fcrtflod tgr
FIGURE 7
Data form
28
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previous two week period. Summary reports may be provided on request.
The reports contain all the responses to questions on the data forms. If
a form was not fully completed, this section will be blank on the report.
Certain omissions, such as a start or stop date/time, make It Impossible
to calculate a radon value. The canister, however, Is counted and the
count data filed by canister serial number. If the missing data are
supplied at a later date, the results will be calculated and reported on
the next repqrt. If any Irregularities are noted In a canister, such as
the top not taped properly, this will be noted in the comment section of
the report. The responsible agency conducting the survey will be notified
i
by telephone if any canister result Is greater than 100 pCI/Hter.
Agencies conducting surveys with the EERF canisters who have the
appropriate computer equipment may access their data directly in the CERF
computer. They will be given access only to their own data and will only
be able to receive data from the EERF system. The EERF also can arrange
to send data directly to agencies who have access to electronic mall.
Interested persons should contact the EERF to arrange to get computer
access or electronic mail.
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REFERENCES
A163 Altshuler, B. and Paste mack, B., Statistical Measures of the
Lower Limit of Detection of a Radioactivity Counter, Health
Physics, Vol. 9, pp. 293-298.
Co83 Cohen, B.L. and Cohen, E.S., Theory and Practice of Radon
Monitoring by Adsorption In Charcoal, Health Physics, Vol. 45,
No. 50, 1983.
Co86 Cohen, B.L. and Nason, R., A Diffusion Barrier Charcoal
Adsorption Collector for Measuring Radon Concentration In Indoor
Air, Health Physics, Vol. 50, No. 4, 1986.
EPA86 Environmental Protection Agency, Interim Indoor Radon and Radon
Decay Product Measurement Protocols, EPA 520/1-86-04.
Ge84 George, A.C., Passive, Integrated Measurement of Indoor Air Using
Activated Carbon, Health Physics, Vol. 46. No. 4. 1984.
Pr85 Prkhard, H.M. and Marlon, K., A Passive Diffusion Rn-222 Sampler
Based on Activated Carbon Adsorption, Health Physics, Vol. 48,
No. 6, 1985.
Ro65 Rosensteln, M. and Goldln, A.S., Statistical Techniques for
Quality Control of Environmental Radloassay, Health Laboratory
Science, Vol. 2, pp. 93-102.
30
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EWIROWEMM. RADIATION DMA (ERD) is published quarterly
(January, April, July, CctoEerT by the 0* S. Environmental
Protection Agency's Office of Radiation Programs.
Requests for information concerning publication and distribution
of ERD should be directed to:
Charles H. Petto
Technical Support Branch
Eastern Environmental Radiation Facility
1890 Federal Drive
Montgomery, Alabama 36109
Requests for information concerning the operation of ERAMS
should be directed to:
Charles R. Phillips, Chief
Monitoring and Analytical Services Branch
Eastern Environmental Radiation Facility
1890 Federal Drive
Montgomery, Alabama 36109
or to:
James H. Gunter, Chief
Environmental Studies and Statistics
Analysis and Support Division (ANR-461)
U. S. Environmental Protection Agency
Waterside Mall East
401 H Street, SW
Washington, DC 20460
***
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