oERA
United States
Environmental Protection
Agency
Method 903.1, Revision 1.0: Radium-226 in Drinking
Water Radon Emanation Technique

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Questions concerning this document should be addressed to:
Glvnda A. Smith, Ph.D.
U.S. EPA, Office of Ground Water and Drinking Water, Standards and Risk Management Division,
Technical Support Center, 26 W. Martin Luther King Dr., Cincinnati, OH 45268
Phone:(513)569-7652
smith.glvndagepa.gov
Office of Water (MS-140)
EPA 815-B-21-003
January 2021
Authors
Glynda A. Smith, Ph.D., U.S. EPA (Cincinnati, OH)
Steven C. Wendelken, Ph.D., U.S. EPA (Cincinnati, OH)
Ack
John Griggs, Ph.D., National Analytical Radiation Environmental Laboratory (NAREL), Office of Radiation
and Indoor Air (ORIA), USEPA.
Keith McCroan, Ph.D., National Analytical Radiation Environmental Laboratory (NAREL), Office of
Radiation and Indoor Air (ORIA), USEPA.
Bahman Parsa, Ph.D., Environmental and Chemical Laboratory Services, PHEL/PHILEP, New Jersey
Department of Health.
Bob Read, Ph.D., Environmental Chemistry Laboratory, Division of Laboratory Services, Tennessee
Department of Health.
Robert L. Rosson, CSRA, LLC, Alexandria, Virginia.
Bob Shannon, Quality Radioanalytical Support, LLC, Grand Marais, Minnesota.
Larry F. Umbaugh, CSRA, LLC, Alexandria, Virginia.
Disc
Publication of the method, in and of itself, does not establish a requirement, although the use of this
method may be specified by the EPA or a state through independent actions. Terms such as "must" or
"required," as used in this document, refer to procedures that are to be followed to conform with the
method.
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Contents
1	Scope and Application	1
2	Summary of the Method	1
3	Definitions	1
4	Interferences	3
5	Safety	3
6	Equipment and Supplies	3
7	Reagents and Standards	4
8	Sample Collection, Preservation, and Storage	6
9	Quality Control	7
10	Calibration	11
11	Procedure	12
12	Data Analysis and Calculations	14
13	Pollution Prevention	19
14	References	19
15	Figures	21
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1 Scope ..Ik! Mb''1":¦ «i!" ¦!'
1.1	Background
Method 903.1, Revision 1.0 is a method for the determination of radium-226 in drinking water. This
method is specific for Ra-226 and is based on the emanation and alpha scintillation counting of radon-
222, a daughter product of radium-226.
1.2	Drinking Water Regulatory Requirements
The Code of Federal Regulations (CFR) at 40 CFR 141.66(b) specifies a maximum contaminant level
(MCL) for combined radium-226 and radium-228 of 5 pCi/L. Laboratories using Method 903.1 to
measure Ra-226 must be able to achieve the required detection limit for radium-226 of 1 pCi/L as
specified at 40 CFR 141.25(c)(1).
1.3	Sensitivity
The sensitivity of the method is a function of sample size, instrument background, cell calibration factor,
and counting time.
2	Summary of the Method
The radium-226 in a drinking water sample is concentrated and separated by coprecipitation with
barium sulfate. The precipitate is dissolved in basic ethylenediamine tetraacetic acid (EDTA) solution,
placed in a sealed bubbler and stored for ingrowth of radon-222. After ingrowth, the radon is purged
into an alpha scintillation cell. About four hours after radon-222 collection, the alpha scintillation cell is
counted for alpha activity.
3	1
3.1	Activity
Rate of nuclear decay occurring in a body of material, equal to the number of nuclear disintegrations per
unit time.
3.2	Batch, Preparation
A set of up to 20 environmental field samples of the same matrix that are prepared and/or analyzed
together with the same instrumentation and personnel, using the same lot(s) of reagents, with a
maximum time between the start of preparation of the first and last sample in the batch being 24 hours.
3.3	Detection I
The DL for radionuclides in drinking water is defined in 40 CFR 141.25(c) as the radionuclide
concentration that can be counted with a precision of plus or minus 100 % at the 95 % confidence level
(1.96a, where a is the standard deviation of the net counting rate of the sample).
3.4	Duplic
A second aliquot of a field sample that is processed in the same manner as the samples in the
preparation batch. Analysis of the DUP provides a measure of the precision associated with batch
preparation.
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3.5	Field Blank
Samples preserved with reagents that are not provided by the laboratory should be accompanied by a
field blank sample that is preserved in the same manner as the submitted samples. The field blank is a
volume of blank matrix that is placed in a clean sample container, preserved in the field, shipped along
with the samples and subjected to the same analytical procedures as the samples. A sample of the
preservative should also accompany the field samples to determine whether it contributes any
contamination.
3.6	Laboratory Fortified I
The LFB consists of a volume of a blank matrix to which a known activity of a radioisotope has been
added. The LFB is processed in the same manner as the samples in the preparation batch, and its
purpose is to determine whether the methodology is in control, and whether the laboratory is capable
of making accurate measurements.
3.7	Laboratoi ?ent Blank (ILIRB)
The LRB consists of an aliquot of a blank matrix that is processed in the same manner as the samples in
the preparation batch, including exposure to all glassware and equipment that are used in the
preparation batch. The LRB is used to assess the process of handling, preparation and analysis for cross-
contamination and for low-level analytical bias.
Laboratory Fortified Sample Mati i ill II 5M)
An aliquot of a field sample to which a known activity of the radionuclide(s) being measured has been
added. The LFSM is processed in the same manner as the samples in the preparation batch. Its purpose
is to determine whether the sample matrix contributes bias to the results. The native level of the
radionuclide(s) must be determined in an unspiked field sample aliquot in order to correct for levels
already present in a sample that could contribute to the LFSM response.
Laboratory Fortified Sample Matrix Duplicate (ILIFSMID)
An additional aliquot of a field sample that has the same quantity of radionuclide(s) added to it as the
LFSM. The LFSMD is processed in the same manner as the samples in the preparation batch. It may be
used in place of the DUP to assess preparation batch precision.
3.10	Picocurie (pQ)
The pCi is the quantity of radioactive material producing 2.22 nuclear disintegrations per minute.
3.11	Uncer	anting
The component of measurement uncertainty attributable to the random nature of radioactive decay
and radiation counting.
3.12. Uncer
An estimate of the measurement uncertainty expressed as one standard deviation.
3.13 Uinceiri.iiiii , II [• iii
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4 Interferences
4.1 Short-lived Gaseous Alpha - e irn ii 11 ii i Jiion uclliides
Gaseous alpha-emitting radionuclides, namely radon-219 and radon-220, have the potential to interfere.
Their half-lives are 3.9 seconds and 54.5 seconds, respectively, and they decay before the radon-222 is
counted. Only their alpha-emitting decay products could interfere, but such interference in drinking
water samples is expected to be rare.
5	Safety
The specific toxicity of each reagent used in this method has not been precisely defined. Each chemical
should be treated as a potential health hazard, and exposure to these chemicals should be minimized.
Each laboratory is responsible for maintaining a chemical hygiene plan (CHP) with an awareness of the
appropriate regulations regarding safe handling of chemicals used in this method. A reference file of
safety data sheets (SDSs) should be made available to all personnel involved in the preparation of
samples and their analyses.
6	Equipment and Supplies
6.1 All|f intiiIllation Counter System
For the specific measurement of radium-226 by the radon emanation method, an alpha scintillation
system designed to accept alpha scintillation flasks (e.g. Lucas cells) shall be used. The counter system
consists of a light-tight enclosure capable of accepting alpha scintillation cells (Section 6.2.2),
photomultiplier tube, and appropriate electronics such that the background counting rate for the
system without the presence of an alpha scintillation cell is < 0.03 cpm.
6.2. Radon Emanation apparatus
The complete radon emanation apparatus is shown in Section 15. Figure 1.
6.2.1	Radon Bubblers
Bubblers (Section 15. Figure 2) equipped with gas-tight stopcocks and fritted glass disks of medium
porosity. Use one bubbler for radium-226 standard solution, one for each sample, and one for each QC
check in the preparation batch.
NOTE: The method results in a final volume of at least 20 mLs. Purchase bubblers accordingly.
6.2.2	Alpha Scintillation Cells
Alpha scintillation cells (Section 15. Figure 3), Lucas-type, or equivalent, with volume capacity of 95-140
mL.
6.3	Absorption Tube
Glass drying tube, 100 mm in length and maximum 10 mm inner diameter. Insert a small glass wool plug
at the lower end. Fill the upper half of the tube with magnesium perchlorate and the lower half with
carbon dioxide adsorbent (Section 15. Figure 1).
6.4	Manometer/Vacuum Gauge
Open-end capillary tube or vacuum gauge having a volume that is small relative to the volume of the
alpha scintillation cell, 0 to 760 mm Hg.
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6,5 Electir Plate
Centrifuge
6.7	Beakers
Beakers of various sizes as appropriate for sample preparation.
6.8	Pipettes
Pipettes of various sizes.
Analytical Balance
The analytical balance with a readability of 0.1 mg.
6.10	Drying Oven/He
Drying oven capable of maintaining a temperature of 105 °C ± 2 °C. Alternatively, heat lamps may be
used if a drying oven is not available.
6.11	Desiccator
6.12	Optioi II |iii| merit f hi pi! Determination
6.12.1	pH Meter
Potentiometer with glass electrode, reference electrode, and temperature compensation capability.
6.12.2	pH Paper
Short range (pH 3.0 - 5.5) and wide range (pH 1 - 14).
7 I 1 IS >!. I " >11. I .1 J
Analytical reagent grade or better chemicals should be used. Commercial reagents are often not tested
for trace radioactivity. Therefore, analysts need to carefully monitor their laboratory reagent blank (LRB)
control charts to identify situations where levels of radioactivity may be present in reagents that could
compromise results.
NOTE: Laboratories can adjust reagent and solution volumes as appropriate to meet testing needs
provided the molar ratios are maintained.
7.1	IDiistiiIIIIecl/IDeiioniized Water
Distilled or deionized water meeting the requirements of ASTM Type 1, 2 or 3 reagent water.
7.2	Acetic Acid
Acetic acid, glacial CH3COOH, concentrated (17.4 M), sp.gr. 1.05, 99.8%.
7.3	Aim ni (	J ir oxide
Ammonium hydroxide, NH4OH, concentrated, sp.gr. 0.90, 56.6%.
7.4	Aniirm Sulfate (200 inig/inilL)
Prepare by dissolving 20 grams (NhUhSCU in a minimum amount of water and dilute to 100 mL.
7.5	Carbon Dioxide Adsorbent
Ascarite™, drying sorbent: 8-20 mesh, or equivalent carbon dioxide adsorbent.
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7.6 Barium 11 .1111 ~i ¦ 111 in 1 Ba;' ml "
Prepare carrier by dissolving about 2.8 g BaCl2*2H20 in water, adding 0.5 mL 16 M HN03, and diluting to
100 mL with distilled/deionized water. Alternately, purchase a high purity commercial barium standard
solution and dilute appropriately. Standardize in triplicate using one of the options described below.
Note: Use the appropriate calculations in Section 12.1 to determine yield.
7.6.1 Standardize According to Approach Used to Determine Yield (Review Section 11.15)
7.6.1.1	Standardize Barium for Chemical Yield
Pipette 2.00 mL carrier solution into a centrifuge tube containing 15 mL water. Add 1 mL 9 M H2S04 with
stirring and digest precipitate in a hot (near boiling) water bath for 10 minutes. Cool, centrifuge, and
decant the supernatant. Wash precipitate with 15 mL water. Centrifuge and decant supernatant.
Transfer the precipitate to a tared stainless steel planchet with a minimum of water. Dry in a 105 °C ±
2 °C oven for two hours (or alternately, dry under a heat lamp). Cool and store in a desiccator, and
weigh as BaS04. Verify the average mass is within ±5 % of the expected mass with a relative standard
deviation between the replicates of < 5%. Calculate the barium content:
Ba in mg/mL =	VolumeBa»	
Substituting (137.34 g/mole Ba2+/233.404 g/mole BaS04) = 0.5884, and 2.00 mL carrier volume yields:
_	(mg BaS04) x (0.5884)
Ba+ in mq/mL =	
w/	2.00 mL
NOTE: If barium-133 will be used as a tracer for radiochemical analysis, the barium carrier prepared in
Section 7.6 does not need to be separately standardized.
7.6.1.2	Standardize Using Barium-133 Tracer for Radiochemical Yield
Add barium-133 tracer solution to the prepared barium carrier solution (Section 7.6) at a level that will
yield at least 6000 - 8000 pCi/100 mL. Pipette 2.00 mL of the prepared barium carrier containing the Ba-
133 tracer into a gamma spectrometer-compatible container containing about 18 mL basic EDTA
(Secti ). Ba-133 is gamma counted long enough so about 10,000 counts above background are
accumulated. Verify that the Ba-133 activity is within ±5 % of the expected level with a relative standard
deviation between the replicates of <5%. This method does not discuss specifications related to
analytical requirements for gamma spectrometers; however, laboratories incorporating barium-133 as a
tracer will be expected to document energy and efficiency calibration as well as performance checks
related to verifying detection efficiency, energy calibration, background, and peak resolution. The
procedure for determining yield using the tracer is discussed in Section 11.15.2.
7.6.1.3	Standardize Using Atomic Spectroscopy Methods for Chemical Yield
Standardize barium carrier prepared in Section 7.6 using approved atomic spectroscopy methods (e.g.
ICP-AES, ICP-MS). The average barium level determined should be within ±5 % of the expected level with
a relative standard deviation between the replicates of <5%. This method does not define specifications
related to the analytical requirements for the instrumentation discussed in the atomic spectroscopy
methods. Laboratories will be expected to document calibration and quality control performance checks
as described in those methods. The procedure for determining yield is discussed in Section 11.15.3.
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7.7 Ell11II II . I- II ¦" gent (0.25 M)
Prepare by dissolving 20 g NaOH in 750 mL water, heat and slowly add 93 g ethylenediamine tetraacetic
acid disodium salt dihydrate (Ci0Hi4N2Na2O8*2H2O). Heat and stir until dissolved, filter through coarse
filter paper and dilute to 1 L.
7.3 Gas Supply
Preferably helium in a high-pressure gas cylinder with a two-stage pressure regulator and needle valve.
Alternately, nitrogen or aged air may be used.
7.9	Hydrochloric Acid (12 M)
Hydrochloric acid, HCI, concentrated (12 M), sp.gr. 1.19, 37.2%
7.10	Magin	chlorate
Magnesium perchlorate, Mg(CI04)2, reagent grade
7.11	Sodium Hydroxi
Prepare by dissolving 40 g NaOH in 50 mL water and dilute to 100 mL.
ant
Radium-226 standard traceable to a national metrology institute (such as the National Institute of
Standards and Technology [N 1ST]). Prepare a standard working solution equivalent to about 50 pCi
radium-226 per mL.
NOTE: After making a working solution from the standard, verify the concentration by conducting at
least three separate verification measurements to confirm that each individual measurement is within
5 % of the expected value.
NOTE: Prepared standards and working solutions should be assigned unique identification numbers
traceable to the original standard and labeled with expiration dates.
7.13	Sulfuric ^
Sulfuric acid, H2S04, concentrated (18 M), sp.gr. 1.84
7.14	Sulfuric £
Carefully mix one volume concentrated H2S04 (18 M) with one volume of water.
7.15	Sulfuric A 05 M)
Prepare by mixing one volume 9 M H2S04 with 179 volumes of water.
8 Sample Collection, Preservation, and Storage
8.1 Containers
Collect samples in glass or plastic containers. A sample volume of 1 gallon (approximately 4 liters) is
recommended for collection of drinking water samples, but collection volume is left to the discretion of
the laboratory.
Sample Collection for Drinking Water
Open the cold water tap and allow the system to flush until the water temperature has stabilized (about
3 to 5 minutes). Collect samples from the flowing system. If the samples are preserved with reagents
(i.e. nitric acid) that are not provided by the laboratory, the samples should be accompanied by a Field
Blank (Section 3.5) that is preserved in the same manner as the samples. A sample of the preservative
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used in the field should also accompany the samples and Field Blank to the laboratory to determine the
contribution, if any, from the addition of the preservative.
NOTE: This section describes collection of drinking water samples at the entrance to the distribution
system. Other guidance may apply for collection of water samples for other programs.
8.3	Preservation
Sample should generally be preserved at the time of collection by adding enough nitric acid to the
sample to bring it to a pH < 2 (e.g. 1-2 mL 16 M HN03 per liter of sample will generally yield a pH < 2).
Alternate concentrations of HN03 are permitted, although the volume added to achieve a pH < 2 should
not exceed 30 mL/L. If the samples are preserved in the field using acid that has not been supplied by
the laboratory, add the same level of acid to a Field Blank (Section 3.5). The pH of all samples must be
verified upon receipt in the laboratory. If the pH is > 2, treat the sample as if it were collected without
preservation as described in Section 8.4.
NOTE: Drinking water samples do not require thermal preservation.
8.4	I	served Samples and Storage
If samples are collected without preservation, they must be received by the laboratory within 5 days,
then preserved with 16 M HN03 to a pH < 2 and held in their original containers for a minimum of 16
hours. The 16-hour waiting period helps solubilize finely suspended materials or surface adsorbed
materials. Verify that the pH is < 2 before preparing the samples for analysis.
NOTE: Screen sample preservatives used by the laboratory (or by field samplers) for radioactive content
by lot number prior to use if possible, to verify that preservatives will not introduce radioactive
contamination.
NOTE: Drinking water compliance samples must be prepared 'as received' (i.e. not filtered). Other
programs/projects may have alternate requirements. If such programs/projects specify filtration, it must
be performed prior to preservation.
NOTE: The requirement for pH < 2 adequately addresses radionuclides of concern for drinking water
compliance samples; however, that may not be adequate for programs evaluating other radionuclides in
non-drinking water matrices. Other programs should optimize sample preservation as appropriate to
address such radionuclides of concern.
NOTE: The laboratory needs to have appropriate segregation procedures in place to prevent cross
contamination of samples.
9 Quality Control
9.1 QC Requirements
QC requirements include an Initial Demonstration of Capability (IDC), ongoing Demonstration of
Capability, and ongoing QC requirements that must be met when preparing and analyzing drinking
water compliance samples. This section describes QC parameters, their required frequencies, and
performance criteria that must be met in order to meet EPA quality objectives for drinking water
analyses. These QC requirements are considered the minimum acceptable QC criteria. Laboratories are
encouraged to institute additional QC practices to meet their specific needs.
9.1.1 In II Demonstration of Capability
A successful IDC must be performed by each analyst prior to analyzing any field samples. Before
conducting the IDC, set up and calibrate the instrument as described in Section 10. The IDC consists of
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the following: demonstration of low system contamination (Section 9.1.1.1). demonstration of accuracy
(Section 9.1.1.2) and confirmation of method sensitivity through a DL study (Section 9.1.1.3).
NOTE: The primary analyst is responsible for conducting a full DL study along with the demonstration of
low system contamination and demonstration of accuracy. Other analysts/technicians that may also be
responsible for performing the method can document their IDCs by either conducting a DL study or by
evaluating four LRBs (Section 9.1.1.1) and four LFBs (Section 9.1.1.2) and successfully meeting the
specified acceptance criteria.
9.1.1.1	Demonstration of Low System Contamination
Contamination due to sample processing is assessed by counting at least four LRBs (Section 3.7). For
drinking water, the LRB volume should be the same as the volume used in establishing detection
capability (Section 9.1.1.3) and representative of typical drinking water sample volumes. LRBs are
prepared and handled like samples following the procedure described in Section 11. Each LRB result
must be below the radium-226 detection limit of 1 pCi/L.
9.1.1.2	Demonstration of Accuracy
Initial demonstration of accuracy is verified by preparing and counting at least four LFBs (Section 3.6)
according to the procedure in Section 11. The recommended LFB fortification with radium-226 standard
is about 2.5 - 5 pCi/L. The average recovery for the LFBs must be within ±10 % of the known amount of
added radium-226 activity.
9.1.1.3	Detection Limit Study
Laboratories testing drinking water samples for Safe Drinking Water Act compliance monitoring need to
confirm detection capability by performing a Detection Limit (DL) study. After calibrating the instrument
as described in Section 10. fortify seven LFBs with the radium-226 standard at activity concentrations
near the 1 pCi/L required detection limit. Prepare and analyze the LFBs following the procedure
described in Section 11. Calculate the DLs as described in Section 12.6.
NOTE: Further discussion of the drinking water DL procedure along with derivation of the final DL
equation from the 40 CFR 141.25(c) definition can be found in Procedure for Safe Drinking Water Act
Program Detection Limits for Radionuclides, USEPA 815-B-17-003, April 2017.
NOTE: Programs that do not analyze drinking water compliance samples may have alternate detection
capability requirements.
9.1.1.4	Excep tion for Experienced Analysts
If an analyst has at least one year of experience preparing and analyzing LRBs and LFBs for a radon
emanation method for Ra-226 determination (such as a previous version of EPA Method 903.1), and
there have been no changes to the instrumentation, previously documented data may be used to fulfill
the IDC low system contamination and accuracy requirements. Ongoing demonstrations of capability
(Section 9.1.2) will verify analyst conformance to the criteria described in this revised method.
9.1.2 Ongoing Demonstration of Capability
Ongoing demonstrations of capability may be fulfilled by repeating the IDC studies described in Sections
9.1.1.1-9.1.1.2 annually or by documenting batch QC LRBs and LFBs that an analyst has processed during
the year since the last demonstration of capability. The data for at least four LRBs processed in different
batches can be used to assess sample processing contamination and the data for at least four LFBs
processed in different batches can be used to assess accuracy. The amount of the Ra-226 standard
added to the sample batch LFBs should follow the guidance described in Section 9.I.I.2.
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9.2 Ongoing QC Criteria
This section summarizes ongoing QC criteria that must be followed when processing and analyzing
drinking water compliance samples.
9.2.1	Alpha Scintillation Counter System Calibration Stability Checks
The calibration stability of each alpha scintillation counter system is checked either weekly or each day
prior to use (whichever is more frequent) to verify the instrument response has not changed since it was
calibrated. Calibration stability is verified by counting a QC check source. The check source does not
have to be NIST-traceable but must have a documented count rate. Count the check source long enough
to obtain about 10,000 counts (1% counting uncertainty). Record and monitor measurements on a
control chart. If instrument control measurements exceed their control limits or exhibit a significant
change in performance, the counter system is placed out of service until stability of the system relative
to the initial calibration can be demonstrated.
9.2.2	Alpha Scintillation Cell Factor Verification Checks
Each alpha scintillation cell factor is verified either quarterly or every ten uses (whichever is more
frequent) by performing the calibration described in Sections 10.3-10.4 using the retained radium-226
standard (Section 10.5) or a freshly prepared standard, as needed. Record and monitor calculated cell
factor values on individual alpha scintillation cell control charts. If a cell factor exceeds its control limits,
re-analyze the radium-226 standard. If the change in the cell factor is confirmed, it is left to the
discretion of laboratory management whether to accept the new cell factor for subsequent data
reduction or place the alpha scintillation cell out of service.
NOTE: Each alpha scintillation cell is calibrated relative to a specific alpha scintillation counter system. If
there are multiple counters available, be sure each cell is attached to the correct system.
9.2.3	Alpha Scintillation Cell Background Determination
Each alpha scintillation cell's background is measured and recorded prior to measurement of compliance
monitoring samples in order to determine the background subtraction value used for calculations.
Attach the alpha scintillation cell to the radon emanation apparatus (Section 15. Figure 1). The radon
bubbler (normally used for samples) is substituted with a glass tube with a stopcock so the gas can be
admitted directly to the alpha scintillation cell. With the stopcock to the gas closed, open the stopcock
on the alpha scintillation cell and then open the stopcock to the vacuum source to evacuate the cell.
Close the stopcock to the vacuum source and monitor the manometer (or vacuum gauge, depending on
set-up) to verify there are no leaks. Open the stopcock to the gas and allow gas to fill the alpha
scintillation cell until atmospheric pressure is attained. Close the stopcock to the cell and shut off the
gas. Place the alpha scintillation cell on the photomultiplier tube within its assigned counter system. It is
recommended that counting be delayed 3-4 hours in order to allow any non-purged Rn-222 progeny to
decay. Then count to assess background count rate (usually over a period of about 100 minutes). Record
and monitor background measurements on control charts. If the alpha scintillation cell background
exceeds its control limits, place the cell out of service until background decays to a level that will allow
the required detection limit to be met within a reasonable counting time.
9.2.4	Control Charts
Analysts are responsible for preparing and maintaining control charts. After a sufficient number of
checks have been obtained (usually at least 20 measurements), calculate the mean values on the control
charts. Establish warning limits at ±2 standard deviations and control limits at ±3 standard deviations
relative to the mean values. Monitor control charts to ensure measurements remain in statistical control
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relative to the control limits. Also, monitor control charts to ensure performance does not change
significantly (i.e., drifting or trending of responses) relative to the time of the initial calibration.
9.2.5	Laboratory Reagent Blank (ILRIB)
An LRB (Section 3.7) must be prepared with each preparation batch to confirm there is no significant
contamination introduced in processing the batch which would contribute bias to the analytical results.
Ensure that LRB activity does not exceed the regulatory DL as described in Section 9.1.1.1, Record LRB
activities on control charts and monitor for trends that could indicate the need for corrective action.
9.2.6	Laboratory Fortified Blank (LFB)
An LFB (Section 3.6) must be prepared with each preparation batch to assess batch accuracy
independent of sample matrix effects. Fortify with radium-226 standard at a level between the required
detection limit and the MCL. Accuracy as percent recovery must be within ±10 % of the amount of
activity added. If the LFB fails to meet the recovery criterion, the batch is considered compromised
which may be due to a change in the alpha scintillation cell response. Re-prepare the sample batch with
new QC checks provided sufficient volume is available. Otherwise, a new set of samples should be
collected. Record and monitor LFB recoveries on control charts.
9.2.7	Laboratory Fortified Sample Matrix (LFSIIVI)
Prepare one LFSM (Section 3.8) per preparation batch. Spike the LFSM with a known activity of radium-
226 standard that is approximately 10 times the anticipated level in the samples or at least 10 times the
DL (i.e. 10 pCi/L). Accuracy as percent recovery must be within ±20 % of the amount of activity added. If
the LFSM fails to meet the recovery criterion, recount the samples, if practical or re-prepare the sample
batch with new QC checks provided sufficient volume is available. Otherwise, flag sample results in the
batch as possibly biased low or high (as the LFSM result indicates) due to matrix effects. Record and
monitor LFSM recoveries on control charts.
NOTE: If Ba-133 tracer is incorporated in each sample, a LFSM is not required with each batch. The
tracer yield will indicate if there are matrix interference issues.
9.2.3 Duplicate (DUIP) or Laboratory Fortified Sample Matrix Duplicate (LFSMD)
Batch precision is assessed through preparation of either a DUP (Section 3.4) or a LFSMD (Section 3.9)
with every preparation batch. The LFSMD is spiked at the same level as the LFSM. Precision is assessed
by calculating the relative percent difference (RPD). RPD must be < 20 %. If the RPD exceeds 20 %, and a
duplicate sample measurement is < 5X the DL, calculate the normalized absolute difference (NAD).
Calculations for the RPD and NAD are provided in Section 12.7. A sample/DUP or LFSM/LFSMD that fail
the batch precision requirement need to be recounted. If the reanalysis fails, it may be an indication of a
lack of sample homogeneity and all sample results in the preparation batch should be reported with a
qualifier indicating questionable precision. If a client requires unqualified results, prepare a new sample
batch with new QC checks provided sufficient volume is available. Otherwise, a new set of samples
should be collected. Record and monitor RPD and NAD on control charts.
9.2.9 Field IB Ian I sded)
If a Field Blank (Section 3.5) is provided with the samples, prepare and analyze it to confirm that field-
supplied preservative does not contribute radioactive contamination to the analytical results.
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10 Calibration
10.1	Instrument Setup
Establish appropriate operating conditions as recommended by the alpha scintillation counter
manufacturer. Calibrate each alpha scintillation cell counter system, determine the alpha scintillation
cell calibration factor and background as described below. Following instrument repairs, perform a
counter system calibration stability check, alpha scintillation cell factor verification check and
background check as described in Sections 9.2.1 - 9.2.3. If the counter system calibration stability check
fails, take corrective action (which may entail re-establishing instrumental operating conditions and
recalibration). Corrective actions for cell factor verification and background check failures are discussed
in Sections 9.2.2 and 9.2.3. respectively.
10.2	Prepare Bubbler with Ra-I inclaircl
Properly secure a radon bubbler (e.g. clamp to a ring stand or other sturdy apparatus). Attach to gas
supply but keep the inlet stopcock closed. Add 1 mL of radium-226 standard solution (Section 7.12). 2
mL prepared barium carrier (Section 7.6, see Note below also) and 1 mL concentrated HCI (Section 7.9).
Add 16 mL distilled/deionized water to yield a total volume of about 20 mL in the bubbler.
NOTE: If Ba-133 is used as a yield monitor, do not incorporate it in the barium carrier added to the Ra-
226 standard bubbler.
10.3	Pui bbler and Begin Rn-222 Ingrowth
Attach an outlet stopcock to the bubbler and keep it open. Adjust the gas regulator so a slow stream of
gas will flow with the needle valve open. Attach the gas supply to the bubbler inlet and slowly open the
inlet stopcock to control the rate of bubbling. Allow the gas to bubble through the solution for 15 - 20
minutes to flush out all radon-222. In rapid succession, close the inlet stopcock, the outlet stopcock and
shut off and remove the gas connection. Record the date and time to establish the zero point for radon-
222 ingrowth. Store the bubbler for at least 18 hours.
NOTE: At 18 hours, the fraction of ingrowth is less than 20 %. A longer ingrowth period is encouraged
when practical.
10.4	Collect and Count Rn-222
Proceed with steps in Sections 11.8 - 11.14 for radon emanation and counting. The alpha scintillation
cell calibration factor is determined from the radium-226 activity and ingrowth of radon-222 as
described in Section 12.3. The calibration factor includes the emanation efficiency of the system, the
counting efficiency of the alpha scintillation cell, and assumes that polonium-218 and polonium-214 will
be in full secular equilibrium with radon-222 when the sample is counted 4 hours after the emanation
procedure. A 100-minute counting time will usually be sufficient for the standard.
10.5	Re	ler with Ra-226 for Ongoing Verification of Cell Factors
The bubblers used for the calibration with radium-226 standard solutions are not used for sample
analysis. They should be set aside and retained with the standard solution prepared in Section 10.2 for
future alpha scintillation cell factor calibrations and verifications. Verify the cell factor for each alpha
scintillation cell prior to initial use and, thereafter, at least quarterly or every ten uses (whichever occurs
more frequently).
11
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11 Pro
11.1	Prepare Drinking Water Sample(s)
To each 1000-mL drinking water sample, add 20 mL 12 M HCI and 2.0 mL standardized barium carrier
(16 mg/mL, Section 7.6). Optionally, add barium carrier containing Ba-133 tracer as described in Section
7.6.I.2. Heat to boiling.
NOTE: If there is solid matter in a sample, do not filter before starting the analysis. Follow the
procedural steps through Section 11.4. then address as described in that section.
11.2	Precipitate BaSCH
Cautiously, with vigorous stirring, add 20 mL 9 M H2S04. Digest at a low boil for 5 to 10 minutes, turn off
the heat, and allow the BaS04 precipitate to settle overnight.
11.3	Isolate Precipitate
Decant and discard the supernatant. Slurry the precipitate and transfer to a centrifuge tube with a
minimum amount of 0.05 M H2S04. Centrifuge and discard the supernatant. Wash the precipitate with
approximately 10 mL 0.05 M H2S04. Centrifuge and discard the supernatant. Wash the precipitate again
with approximately 10 mL 0.05 M H2S04. Centrifuge and discard the supernatant.
11.4	Dissolve Precipitate with Basil	>llutiion
Dissolve the precipitate by adding 20 mL basic EDTA reagent (Section 7.7). Heat gently (e.g. in a hot
water bath) and stir well. If the precipitate does not readily dissolve, add a few drops 10 M NaOH. If the
precipitate still does not dissolve, verify the pH is greater than 6.9 and adjust if needed. If the original
sample contained solid material and it still has not dissolved at this point, filter the solution into a clean
centrifuge tube.
11.5	Prepare Bubbler
Quantitatively transfer the solution to a radon bubbler.
NOTE: The volume of the bubblers should be greater than 20 mL allowing for some air space above the
liquid level and top of the bubbler. In those instances where the precipitate was difficult to dissolve and
additional basic EDTA was needed to effect dissolution, it may be necessary to place the tube containing
the solution in a boiling water bath to reduce the solution volume prior to transferring it to the bubbler.
11.6	Pui bbler
Attach and open the outlet stopcock on the bubbler, attach the gas supply and purge the solution as
described in Section 10.3. Allow the gas to bubble through the solution for 15 - 20 minutes.
11.7	Begin Rn-222 Ingrowth
In rapid succession, close the inlet stopcock, the outlet stopcock and shut off and remove the gas
connection. Record the date and time to establish the zero point for radon-222 ingrowth. Store the
solution in the bubbler for at least 4 to 8 days.
11.8	Ot . intiiIllation Cell Background
Prior to beginning the analyses, each alpha scintillation cell's background must be determined as
described in Section 9.2.3.
12
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11.9	Prepare Gas Purification Absorption Tube
At the end of the ingrowth period, fill the lower half of an absorption tube (Section 6.3) with carbon
dioxide adsorbent (Section 7.5) and the upper half with magnesium perchlorate (Sectic ).
NOTE: Voids above the bubbler must be kept as small as possible. Capillary tubing should be used when
possible and the drying tube volume with carbon dioxide adsorbent and magnesium perchlorate should
be kept to a minimum. A typical system consists of a drying tube 10 cm x 1.0 cm (ID) with each of the
drying agents occupying 4 cm and separated by small glass wool plugs. The column can be reused
several times before the chemicals need to be replaced.
11.10	Assemble Radon Emanation Apparatu iii'U 		 I| !i cintiiIllation Cell
Attach the absorption tube to the radon bubbler, then attach an alpha scintillation cell to the top of the
tube as shown in Section 15. Figure 1. Be sure all stopcocks are in the closed position. Open the stopcock
to the vacuum source, then open the stopcock to the alpha scintillation cell. Evacuate the alpha
scintillation cell and gas purification absorption tube. Close the stopcock to the vacuum source and
monitor the manometer (or vacuum gauge) reading to check for leaks. Any leaks must be corrected
before proceeding.
11.11	Adj u st G a s IF II ow
Adjust the gas regulator so a slow stream of gas will flow with the needle valve open. The gas pressure
should be adjusted so that the gas flows at slightly above atmospheric pressure, low enough that the
helium flow is sufficient to replace the air drawn through the bubbler by the vacuum created within the
alpha scintillation system and cell. Attach the gas supply to the bubbler inlet but do not open the inlet
stopcock yet.
Pressure
Slowly open the bubbler outlet stopcock to begin equalizing system pressure. Take care to avoid a surge
of pressure forcing liquid out of the bubbler that could clog the absorption tube. When the stopcock is
fully open and bubbling slows and nearly stops, close the bubbler outlet stopcock.
11.13	De-e	in-222
Slowly open the inlet stopcock using bubbling as a guide. When the stopcock can be fully opened
without a significant amount of bubbling, the bubbler is essentially at atmospheric pressure. Open the
outlet stopcock very slightly and allow bubbling to proceed such that 15 to 20 minutes are required to
complete de-emanation. This amount of time is needed to effectively purge radon from the solution and
into the alpha scintillation cell. Toward the end of the de-emanation, when the vacuum is no longer
effective and the system approaches ambient pressure, the helium gas pressure can be increased a
slight amount to facilitate completion of the bubbling. In rapid succession close the stopcock to the
alpha scintillation cell, the bubbler inlet and outlet stopcocks and shut off and disconnect the helium gas
supply. Record the date and time as this is the beginning of radon-222 decay and ingrowth of radon-222
progeny. Save the solution in the bubbler for yield determination (See Section 11.15).
11.14	Ston . iintiiIIlatiion Cell at Least Four Hours then Count
Store the alpha scintillation cell for at least four hours to allow equilibrium between radon-222 and its
progeny. Place the alpha scintillation cell on the photomultiplier tube with the enclosed alpha
scintillation cell counter system. Allow the cell to dark adapt, then begin counting. Record the date and
time counting began and finished in order to correct for radon-222 decay.
13
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11,15 Yield Determination
11.15.1	Yield Determination Based on BaS04 Precipitation
Quantitatively transfer the bubbler solution to a centrifuge tube using several small rinses (1-3 mL) of
distilled or deionized water. Add 1 mL ammonium sulfate (200 mg/mL, Section 7.4) and swirl the tube to
mix well. Add glacial acetic acid (17.4 M) dropwise until precipitation begins, then add 2 mL extra. Digest
in a hot water bath 5 to 10 minutes. Centrifuge, then discard the supernatant. Wash the BaS04
precipitate with 15 mL water, centrifuge and discard the supernatant. Transfer the precipitate to a tared
weighing vessel with a minimum of water. Dry under a heat lamp or in a 105 °C ± 2 °C oven for a couple
of hours or until constant weight is obtained. Cool in a desiccator and weigh. The calculated yield
(Section 12.1.1) must be within 70-110 %. If upon further drying, the yield exceeds 110 %, the sample
may contain a high level of natural barium causing interference. Evaluation of an aliquot of the original
sample by an atomic spectroscopy method can be used to verify native barium levels. Otherwise, the
excess mass may be due to inadequate rinsing of the precipitate and residual ammonium sulfate.
11.15.2	Yield Determination Based on Barium-133 Gamma Activity
Transfer the final solution obtained in Section 11.4 into a container appropriate for gamma counting.
Count the barium-133 gamma activity. The calculated yield (Section 12.1.2) must be within 70 - 110%.
Then quantitatively transfer the solution to a bubbler and continue the procedure as described in
Section 11.6. This approach is used because t it is easier to quantitatively transfer a solution into a
bubbler than out of it.
11.15.3	Yield Determination Using Atomic Spectroscopy Methods
This is best accomplished by preparing a reference standard by pipetting 2.0 mL of prepared barium
carrier that has been standardized as described in Section 7.6.1.3 into a centrifuge tube at the same
time the sample batch is being prepared. Evaporate to dryness and then add 20 mL basic EDTA. Remove
a couple of hundred microliters from this reference standard solution and each of the sample bubblers.
Dilute in parallel to a level that is approximately in the middle of the instrument calibration range.
Analyze using the same atomic spectroscopy method used to standardize the barium carrier. The yield is
determined by assessing the ratio of each sample concentration to the reference standard
concentration. The calculated yield (Section 12.1.3) must be within 70-110%.
11.16 Flush and Evacuate Alpha Scintillation Cell
After each analysis, prepare the alpha scintillation cell for reuse. Evacuate and slowly refill the cell with
counting gas. Repeat the evacuation and filling process at least two more times and store the cell filled
with helium at atmospheric pressure. This procedure removes radon from the cell and prevents build-up
of radon progeny.
I il ".
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Theoretical yield of barium sulfate must be determined based on the standardized concentration of the
barium carrier (Section 7.6.1.1). If the standardized carrier concentration is 16 mg/mL, then the
theoretical 100 % yield of barium sulfate would be 54.38 mg.
The fractional yield would thus be:
m, — mn
Y = —	-
54.38
where
ms= mass of planchet with the dried barium sulfate precipitate, mg
mp= mass of planchet, mg
54.38 = mass of barium sulfate precipitate if all the added barium carrier (32 mg) is recovered. If the
standardized concentration of the barium carrier differs from the 16 mg/mL prepared in Section 7.6. or
if the volume added differs from 2.0 mL, adjust the theoretical Ba2+ concentration accordingly.
12.1.2	Radiochemical Yield (Ba-133 Activity)
Alternately, radiochemical yield based on addition of barium-133 as a tracer is calculated using the
following equation:
Y	= ^-
As
Where
Am= activity of Ba-133 measured in the sample, pCi/mL
y4s= activity of standardized Ba-133 solution, pCi/mL
12.1.3	Chemical Yield (Atomic Spectroscopy)
If chemical yield is determined by employing atomic spectroscopy methods, calculate the yield as:
Ms
Y	= —
Mr
Where
Ms = mass of barium measured in the sample, mg
Mr = mass of barium in reference standard, mg
12.2	Count Rate
The net count rate, i?N, for any single count (sample or standard) is calculated as
_Cs Cb
R"-h tB
where
i?N = net count rate in counts per minute (cpm, min"1)
Cs = number of counts observed over the sample counting period
ts = duration of the sample counting period (i.e., live time) in minutes
CB = number of counts observed over the background counting period
tB = duration of the background counting period (i.e., live time) in minutes
12.3	Allf. Hi iiintiiIllation Cell Calibration II lor
Determination of the alpha scintillation cell calibration factor is described in Section 10. Calculate the
factor for each cell as follows:
Rn	1	1	-^-£3
Ey —	X	TT X TT X	T~
j4Stci 1 — e_/lti e_/lt2 1 — e~Ati
where
15
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sx = calibration factor for alpha scintillation cell x
i?N = net count rate of the Ra-226 standard, counts per minute (cpm, min"1)
j4Std = activity of the Ra-226 standard in the bubbler, disintegrations per minute (dpm, min"1)
A = decay constant for radon-222, in reciprocal days (0.1813 d"1)
f ,= ingrowth time of radon-222, in days (see Section 10.3)
t2= radon-222 decay between de-emanation and initiation of the count, in days (see Section 10.4)
t3 = counting time (real time), in days
NOTE: It is acceptable to perform calculations based on hours using the appropriate radon-222 decay
constant (0.007554 h"1) or minutes (radon-222 decay constant is 0.0001259 min"1). Be consistent to
ensure decay constant and elapsed times are in the same units.
12.4 Uncer
Each Rn-222 atom yields three short-lived alpha-emitting progeny (Po-218, Pb-214 and Bi-214). When
half-life is short relative to the counting time and detector efficiency is high, there is increased
probability of observing a count not only from the parent, but also from the progeny. Lucas and
Woodward (Secti , Reference 10) discussed the effect of non-Poisson counting uncertainty that
results. Thus, for Rn-222, the standard uncertainty ("one-sigma") of i?N is then given by
where J is the variance-to-mean ratio for the counts produced by one atom of 226Ra in the sample.
where t3 is the elapsed time from beginning to end of the counting period (real time) in days, the decay
constants Ai through A4 and coefficients ci through c4 are given by:
Ai = A(222Rn) = 0.181300 d"1
if Rn < 0
; = i + ¦
+ c4( 1 - e-^3)
A2 = A(218Po) = 325.0 d"1
A3 = A(214Pb) = 37.083 d"1
A4 = A(214Bi) = 50.41 d"1
and the coefficients ci through c4 are given by:
ci =	0.666 536
c2 =	-0.000126
c3 =	-0.008 737
c4 =	0.004 843
The square of the standard uncertainty is denoted by u2(i?N).
12,5 Radium- tivity
Calculate the radium-226 activity concentration for each sample.
16
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Radium — 226 Activity pCi/L, =
R*
x
1

1

At3

X

X

1 _ e-At1_
e-At2
1 — Q-^3
£ x V x 2.22 x Y
where
i?N = net count rate, counts per minute (cpm, min"1)
e = alpha scintillation cell calibration factor (as calculated in Section 12.3)
V	= volume of sample aliquot, in liters (L)
2.22 = conversion factor from dpm to pCi
Y	= yield (as calculated in Section 12.1)
A = decay constant for radon-222, in reciprocal days (0.1813 d"1)
f ,= elapsed time between the first and second de-emanations (Sections 11.7 - 11.13), in days
t2= elapsed time between second de-emanation and initiation of counting (Sections 11.13 - 11.14), in
days
t3= counting time (real time), in days
NOTE: It is acceptable to perform calculations based on hours using the appropriate radon-222 decay
constant (0.007554 h"1) or minutes (radon-222 decay constant is 0.0001259 min"1). Be consistent to
ensure decay constant and elapsed times are in the same units.
The radium-226 standard counting uncertainty and expanded counting uncertainty (95 % confidence)
are calculated as:
u(c) =
u2(Rn)
sxVx 2.22 X Y
x
1

1

At3
.(1 — e~Atl).

[(e-Atz)J

1 —
and U95o/o = 1.96 x u(c)
where
u(c) = radium-226 standard counting uncertainty ("one-sigma") in pCi/L
i?N = net count rate, counts per minute (cpm, min"1)
u2(/?n) = standard uncertainty of RN, calculated as in Section 12.4
s = alpha scintillation cell calibration factor
V	= volume of sample aliquot, in liters (L)
2.22 = conversion factor from dpm to pCi
Y	= yield (as calculated in Section 12.1)
A = decay constant for radon-222, in reciprocal days (0.1813 d"1)
f ,= elapsed time between the first and second de-emanations (Sections 11.7 - 11.13), in days
t2= elapsed time between second de-emanation and initiation of counting (Sections 11.13 - 11.14), in
days
t3= counting time (real time), in days
U95o/0 = expanded counting uncertainty (95 % confidence) in pCi/L
1.96 = coverage factor for 95 % level of confidence
NOTE: It is acceptable to perform calculations based on hours using the appropriate radon-222 decay
constant (0.007554 h"1) or minutes (radon-222 decay constant is 0.0001259 min"1). Be consistent to
ensure decay constant and elapsed times are in the same units.
12.6 Safe Drinking Water Act Detection Limit
The detection limit (DL) requirement for drinking water compliance samples is defined in Section 3.3 and
determination of method detection capability is described in Section 9.I.I.3. From the definition, the
equation in Section 12.6.1 can be derived (see reference 9 in Section 14).
17
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12.6.1 IDIL Equation
The single sample drinking water detection limit is calculated as:
DL =
1.962 X
2ts
£ x V x 2.22 x Y x (1 - e-^i) x (e"^)
1 — e-^3
At¦
3
where
ts = sample count time (i.e., live time), in days
tB = background count time, in days
CB = number of background counts
J = variance-to-mean ratio for the counts produced by one atom of 226Ra in the sample (Section 12.4)
s = alpha scintillation cell calibration factor
V	= volume of sample aliquot, in liters (L)
2.22 = conversion factor from dpm to pCi
Y	= yield (as calculated in Section 12.1)
A = decay constant for radon-222, in reciprocal days (0.0181 d"1)
f ,= elapsed time between the first and second de-emanations (Sections 11.7 - 11.13), in days
t2= elapsed time between second de-emanation and initiation of counting (Sections 11.13 - 11.14), in
days
t3= counting time (real time), in days. NOTE: Technically, the difference between ts and t3 is very small
and it can be assumed that ts = t3
NOTE: It is acceptable to perform calculations based on hours using the appropriate radon-222 decay
constant (0.007554 h"1) or minutes (radon-222 decay constant is 0.0001259 min"1). Be consistent to
ensure decay constant and elapsed times are in the same units.
12.6.2 DL Study
The DL study described in Section 9.1.1.3 consists seven replicate laboratory fortified blanks that are
prepared and counted as specified in the method. The replicate results are assessed using a chi-square
statistic to test whether the relative standard deviation of the results exceeds the maximum value
allowed at the required DL.
Calculate the mean of the measured values and the chi-square statistic as follows:
where
n = number of replicate measurements
= activity fortified in sample replicates
To be deemed acceptable, the value of x2 should be less than or equal to the 99th percentile of the^2
distribution with (n-1) degrees of freedom.
n
j=1
And
18
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12.7 Relative Percent Different	:iioin
As described in Section 9.2.8, relative percent difference (RPD) is used to evaluate precision of duplicate
measurements. The RPD is calculated as
where
y4s = net activity of the first aliquot of sample
^dup = net activity of the measurement obtained from a second aliquot of the same sample
If a duplicate sample measurement has an activity < 5x the detection limit and the calculated RPD >
20 %, calculate the normalized absolute difference (NAD). The NAD of the two measurements made
from the same sample assesses whether they are within 2 standard deviations of their aggregate
measurement uncertainty of each other. Calculate the NAD as
where
y4s = net activity of the first aliquot of sample
y4dup = net activity of the measurement obtained from a second aliquot of the same sample
u2(As) = square of the standard counting uncertainty ("one-sigma") associated with ^4S
u2(^dup) = square of the standard counting uncertainty ("one-sigma") associated with ^4dup
If the NAD is less than or equal to 2, then the two measurements are within 2 standard deviations of
each other and therefore acceptable. If, however, the NAD exceeds 2, it is unacceptable since it means
there is > 2 standard deviations of difference between the two measurements drawn from the same
sample. Recount the sample and duplicate. If RPD/NAD evaluation still fails, a new sample and duplicate
should be prepared.
13	Pollution Prevention
The procedures described in this method generate relatively small amount of waste since only small
amounts of reagents are used. The matrices of concern are finished drinking water or source water.
Laboratory waste practices must be conducted consistent with the laboratory's radioactive materials
license and all applicable rules and regulations, and that laboratories protect the air, water, and land by
minimizing and controlling all releases from fume hoods and bench operations. Also, compliance is
required with any sewage discharge permits and regulations, particularly the hazardous waste
identification rules and land disposal restrictions.
14	References
1.	Standard Methods for the Examination of Water and Wastewater, 22nd Ed., American Public
Health Association, Washington, D.C. (2011).
2.	Manual for the Certification of Laboratories Analyzing Drinking Water, Criteria and Procedures
Quality Assurance, 5th Ed., USEPA 815-R-05-004, January 2005.
3.	Multi-Agency Radiological Laboratory Analytical Protocols Manual (MARLAP), NTIS PB2004-
105421, July 2004.
RPD = —i4dup^ X 100 %
NAD =
Ms -^dup
19
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4.	Blanchard, R. L, Uranium Decay Series Disequilibrium in Age Determination of Marine Calcium
Carbonates. Doctoral Thesis, Washington University, St. Louis, Missouri (June 1963).
5.	Ferri, E., Magno, P. J., Setter, L. R., Radionuclide Analysis of Large Numbers of Food and Water
Samples, U. S. Department of Health, Education and Welfare, Public Health Service Publication
No. 999-RH-17 (1965).
6.	Rushing, D. E., The Analysis of Effluents and Environmental Samples from Uranium Mills and of
Biological Samples for Uranium, Radium and Polonium, SM/41-44, Symposium on Radiological
Health and Safety, Vienna, Austria (August 1963).
7.	Youden, W. J., Statistical Techniques for Collaborative Tests, Statistical Manual of the AOAC
Association of Official Analytical Chemists, Washington, D. C. (1975).
8.	Steiner, E. H., Planning and Analysis of Results of Collaborative Tests, Statistical Manual of the
AOAC Association of Official Analytical Chemists, Washington, D. C. (1975).
9.	Procedure for Safe Drinking Water Act Program Detection Limits for Radionuclides, USEPA 815-B-
17-003. April 2017.
10.	Lucas, H.F., Woodward, D.A., Effect of Long Decay Chains on the Counting Statistics in the
Analysis of Radium224 and Radon222, Journal of Applied Physics, 35(2), 452-456. 1964.
20
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15 Figures
Figure 1. Ration emanation apparatus with scintillation cell
21
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Figure 2. A typical radon bubbler
22
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67 mm

90 mm
C1«ar SIie«
Window
1
JUIIilUiHmUllliWttllil
jg—
SO mm
«l
Corning No. 2
or Equivalent
Brass Collar
¦ Kovor Metal
ore 3, A typical scint111 at1 on cell for radon count!
23
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