vvEPA
United States
Environmental Protection
Agency
Environmental Monitoring
Systems Laboratory
P.O. Box S3478
Us Vegas NV 89193-3478
EPA/600/2-87/082
March 1989
Research end Development
Two Test Procedures
for Radon in Drinking
Water
Interlaboratory
Collaborative Study
-------
TWO TtST PR0CEOURES FOR RADO~ IN DRINKING WATER
Interlaboratory Collaborative Study
by
E. L. Wh it taker
Lockheed Engineering and Management
Services Company, Incorporated
Las Vegas, Nevada ~9i14
and
J. D. Akridge and J. Giovino
Nuclear Radiation Assessment Division
Environmental Monitoring Systems Laboratory
Las Vegas, Nevada 89114
Contract Number 6d-U3-3249
Project Officer
'1:)
,~
.~')
r~'
Chung-Ki ng Li u
Nuclear Radiation Assessment Division
Environmental Monitoring Systems Laboratory
Las Vegas, Nevada 89114
~
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ENVIRONMENfAL MONITORING SYSTEMS LABORATORY
UFFICE OF RESEARCH AND DEVELOPMENT
U.S. ENVIRONMENTAL PROTECTION AGENCY
LAS VEGAS, NEVADA 89114
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NOTICE
The information in this document has been funded wholly or in part by the
United States Environmental Protection Agency under Contract Number 68-03-3249
to the Lockheed Engineering and Management Services Company, Incorporated,
Las Vegas, Nevada. It has been subject to the Agency's peer ana administrative
review, and it nas been approved for publication as an EPA document. Mention
of trade names or commercial products does not constitute endorsement or
recommendation for use.
i i
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ABSTRACT
Two analytical methods for the determination of radon in water concentra-
tions were tested in a multi laboratory study with twenty-eight participating
laboratories. Eighteen laboratories analyzed prepared samples by the liquid
scintillation (LS) method, and twelve laboratories analyzed the same samples DY
the Lucas Cell (LC) method. Several laboratories analyzed the samples by both
methods.
Because of the short half life of radon-2~2 (3.dZ days), special standards
and samples were prepared in which each standard and each sample contained its
own sealed radium-Z26 source that emanated radon-222 into the standard and
sample water containment. There was a radon hold-back loss factor associated
with the standards and samples that were provided to the participant labora-
tories. However, because the standards and samples were prepared identically,
tne radon hold-back loss was common to standards and samples alike and tnerefore
did not bias the test results.
A comparison of the grand averages for the three samples with the known
values for those samples showed good accuracy for both methods. The accuracy
index was not less than 94 percent for any of the three samples when analyzed
by either method. The average accuracy for the LS method for the three samples
was 95.2 t 2.0 percent and for the LC method it was 100.7 t 4.0 percent at the
95 percent confidence level.
Test results for the LS method showed better precision than test results
for the LC method. The average repeatability (within-laboratory precision) for
the LS method was 3.6 t 3.0 percent at 9~ percent confidence and for the LC
method it was 6.4 t 3.8 percent at 95 percent confidence. The average repro-
ducibility (combined within- and between-laboratory precision) for the LS
method was 10.2 t 4.2 percent at 95 percent confidence and for the LC method
it was 17.6 t 4.2 percent at 95 percent confidence.
The importance of the sampling technique to the analytical accuracy is
discussed in the report.
The authors and the Project Officer recommend that the two analytlcal
methods be considered as validated and equivalent methods.
i i i
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CONTENTS
Ab s tr ac t. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Tab 1 e s. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Abbreviations and Symbols. . . . . . . . . . . . . . . . . . . . . . . .
Acknowledgment. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
I ntroduct ion. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Conclusions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Recommendations. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Experimental Procedures. . . . . . . . . . . . . . . . . . . . . . . . .
Analytical test procedures. . . . . . . . . . . . . . . . . . . . .
Samp 1 i n g . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Liquid scinti'lation method. . . . . . . . . . . . . . . . . . . . .
Lucas Cell method. . . . . . . . . . . . . . . . . . . . . . . . . .
Collaborative test procedures. . . . . . . . . . . . . . . . . . . .
Standard and sample solutions. . . . . . . . . . . . . . . . .
General procedures. . . . . . . . . . . . . . . . . . . . . . .
Data processing procedures. . . . . . . . . . . . . . . . . . . . .
Re s u It san d D i s c u s s ion. . . . . . . . . . . . . . . . . . . . . . . . . .
References.
. . . . .
. . . . . .
. . . . .
........
. . . . . . .
Appendices
A.
List of Participant Laboratories. . . . . .
. . . . .
. . . . . .
B.
Analytical Test Procedure "The Determination of Radon in
Dr ink i n 9 W a te r". . . . . . . . . . . . . . . . . . . . . . . . .
C.
NIRS Sampling Instructions - Radon
. . . . .
. . . . . . .
. . . .
D.
Analytical Test Procedure "Radon/Water Concentration Analysis of
Grab Samples Using Lucas Scintillation Cell Detectors" . . . . .
E.
F.
Radon Sampling. . .
. . . . .
. . . . . . . .
. . . . . . . . . .
Instructions to Participant Laboratories. .
. . . . . .
. . . . .
v
i i i
vi
vi i
ix
1
J
b
b
6
6
6
1
7
7
7
d
11
l~
2u
a
Lb
n
J4
36
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Number
1
2
3
4
b
6
TABLES
Liquid Scintillation Method
. . . . . . . . . .
. . . . . . . .
Liquid Scintillation Method (Accuracy, Bias and Precision
Summary). . . . . . . . . . . . . . . . . . . . . . . . . . .
Liquid Scintillation Method (First Aliquot Test Results). . . .
Liquid Scintillation Method (Test Results of First and Last
A 1 i quots) . . . . . . . . . . . . . . . . . . . . . . . . . .
Lucas Cell Method.
.........
.......
. . . . . .
Lucas Cell Method (Accuracy, Bias and Precision Summary). . . .
vi
Page
13
14
15
16
17
18
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ABBRU lATIONS
ASfM
c/m or cpm
cpm/dpm
cpm/pCi
dim or dpm
EMSL
EPA
HB/TL
LC
LS
mg
NIPDWR
pCi/L
pCi/mL
Ra-~i::6
Rn-222
SYMBOLS
25%
Ajb
n
p
Sij
Sr j
SLj
SRj
Sxj
Vrj%
VLj%
VR ,%
J
X.
Y~
J
LIST OF ABBREVIATIONS AND SYMBOLS
-- the American Society for Testing and Materials
-- counts per minute
-- counts per minute per disintegrations per minute
-- counts per minute per picocurie
-- disintegrations per minute
-- Environmental Monitoring Systems Laboratory
-- Environmental Protection Agency
-- combined hold back/transfer loss
-- Lucas Cell
-- liquid scintillation
-- milligram (0.001 gram)
-- National Interim Primary Drinking Water Regulations
-- picocuries per liter
-- picocuries per milliliter
-- radium-~26
-- radon-222
-- two sigma percent (two standard deviations in percent)
-- the accuracy index for the sample j
-- the number of replicate analyses
-- the number of participant laboratories in the study
-- the standard deviation of the replicate test results for
sample j by lab i
-- the repeatability (within-laboratory) standard deviation
for sample j
the standard deviation of between-laboratories precision
for sample j
-- the reproducibility (combined within- and between-
laboratory) standard deviation for sample j
-- the standard deviation of the grand average for sample j
-- the coefficient of variation for repeatability (within-
laboratory) for sample j
-- the coefficient of variation for between-laboratories
precision for sample j
-- the coefficient of variation for reproducibility (combined
within- and between-laboratory) for sample j
-- the grand average value for sample j
-- the known value of the sample j concentration (pCi/L)
vii
-------
-Xij
Xijh
-- the aritnmetic average of all replicate test results of
sample J by lab i
-- the test result of replicate h of sample j by lab i
viii
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ACKNOWLEDGMENT
The authors and Project Officer would like to thank all of the participant
laboratories for their voluntary effort in this study. They would also like to
thank Howard Kelley of EPA EMSL-Las Vegas and Loren Berge, Ph.D. (now with the
New Mexico State Health Department) for their assistance in the early experi-
mental and planning stage of the study.
ix
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SECTION 1
INTRODUCTION
There has been an increased awareness and a growing concern of the risk of
lung cancer because of exposures to radon, a gaseous decay product of naturally
occurring radium. The short-lived progeny of radon, two alpha particle emitting
and two beta-emitting radioisotopes, are included in that risk concern.
A common source of radon in household air is from the radium in the build-
ing materials and the surrounding soil. In areas where there are high concentra-
tions of radon in the water being supplied to houses, the water can be a major
source of radon in household air. Any aeration of radon-bearing water in the
house, such as showering or washing dishes and clothes, will release a sig-
nificant fraction of the radon to the air.(l) Therefore, radon in water being
supplied to homes is a great concern.
Most homes in the country are being supplied with water from single
sources, and those supplies must, therefore, be potable water supplies. Any
health hazard associated with potable water supplies is a concern of the EPA
Office of Drinking Water, and maximum allowable concentrations for such health
hazards need to De addressed in the National Primary Drinking Water Regulations.
Methodology for the measurement of radon concentrations in water needs to
be validated. This document is a report of a mu1tilaboratory test of two
test procedures for the purpose of validating those test procedures. In one
method liquid scintillation counting of the alpha and beta particle emissions
from the radon and its short-lived progeny in 1u mL portions of water samples
is used to determine radon/water concentrations. In the second method, the
radon gas is emanated from measured portions of water samples into preevacuated
Lucas cells in which only the alpha particle emissions from the radon and its
short-lived progeny are counted to determine radon/water concentrations. A
third method is being tested in a separate study, which is an alpha track method,
and it will be reported separately.
Radon, a gas that dissolves in water and other solvents, is easily dis-
placed from water by air.(l} The sampling technique is critical to representa-
tive sampling and accurate analysis of water supp"lies that are being monitored
for radon/water concentrations. Therefore, the method of analysis to be used
should include a sampling technique description.
Radon-222/water concentrations in u.S. ground waters are typically
thousands of times higher than the radium-226/water concentrations in the same
ground-water supply systems. Radium-226, the progenitor of _radon-222, is
primarily bound up in the ground-water system acquifers.(2-5) It is, therefore,
1
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desirable to use radium-free, radon/water standards and samples in a multi-
laboratory test of andlytical methods for determining radon/water concentrations.
A radium-free radon/water generating source was Rrepared for the EPA,
EMSL-Las Vegas, by the National Bureau of Standards. (5) That source/device did
not lend itself to the preparation of standards and samples of radon/water that
could be used in a multilaboratory test of two methods of analysis. However,
the investigator in this study successfully prepared a number of relatively
inexpensive radium-226/radon-222 sources that would give repetitive generations
of radium-free radon/water concentrations.
This study was conducted by the principal author as an employee of Lockheed
Engineering and Management Services Company, Inc., for the EPA under Contract
Number 68-U3-3249, Task 7u.12.
2
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SECTION 2
CONCLUSIONS
A satisfactory multilaboratory test of the two analytical methods was
demonstrated by the low number of outlier test results (2 out of 60 laboratory
averages for the liquid scintillation method and none tor the Lucas Cell
method).
Equivalency of the two methods was demonstrated by the high accuracy of
the test results obtained by both methods (accuracy index was not less than ~4
percent for any of the three samples when analyzed by either method) and by the
lack of a serious bias by either method.
A comparison of Table ~ (LS method) with Table 0 (LC method) shows the
liquid scintillation (LS) method had better precision than the Lucas Cell (LC)
method. The average repeatability (within-laboratory precision) for the LS
method was 3.6 ~ 3.0 percent at 95 percent confidence, and for the LC method
was 6.4 ~ 3.8 percent at 95 percent confidence. The average reproducibility
(combined within- and between-laboratory precision) for the LS method was
10.2 ~ 4.2 percent at 95 percent confidence, and for the LC method was
17.6 ~ 4.2 percent at 95 percent confidence.
The type of standards and samples that were used in the multi laboratory
study is described in Section 4, Experimental Procedures, Collaborative Test
Procedures, Standard and Sample Solutions. That type of standards and samples
was used for the following reasons:
a.
There was no natural source of high radon/water concentration available
to the investigator.
b.
Radon-222 has a short half-life (3.8~ days), and because most of the
participating laboratories are located in the eastern part of the
country, a significant transit time was required.
c.
The investigator had determined through experimental study that
multiple radon generating sources could be prepared that would give
repetitive generations of radium-free radon/water standards and samples
at very reasonable cost.
d.
The use of standards and samples that contained their own radon
generating source would make the multilaboratory study much less
time-intensive.
3
-------
There was a corrbined hold-back/transfer radon loss (HB/TL) associated witn
the type of standards and samples that were provided to the participants. How-
ever, since standards and samples were the same type and were treatea in the
same way, the hold-back/transfer radon loss was common to standards and samples
alike and therefore did not bias the test results.
The variations in the cpm/pCi factors in Table 1 are not reflected by
corresponding differences in the sample radon-222 concentration test results.
This shows that the differences in the sample aliquot transfer technique used
by the laboratories did not significantly affect the test results because stan-
dards and samples were transferred by the same technique within each laboratory.
A comparison of the cost per analysis between the two methods favors the
LS method significantly when LS counting capability is available to the analyst.
4
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SECTION 3
RECOMMENDATIONS
The authors recommend that the two analytical methods tested in this
multilaboratory test be considered valid and equivalent for the determination
of radon/water concentrations in potable water systems.
It is recommended that sampling be considered as a critical part of the
analytical procedure for analytical methods that are specified for the determi-
nation of radon/water concentrations. A positive pressure sampling or transfer
technique should be used, and negative pressure techniques, aeration, and
turbulence should be avoided whenever possible.
For the LS method, it is recommended that samples be transferred to LS vials
directly at the sampling site as described in the EPA method (Appendix B) using
a positive pressure technique that is similar to the one described in the NIRS
Sampling Instruction-Radon (Appendix C) and that requires filling the LS vial
only to the shoulder of the bottle should be used. Pre-weighing the LS vials
containing 1U mL of mineral oil cocktail and weighing again after water sample
has been added provides for determining sample size. Poly Seal caps on the LS
vials seem to retain the mineral oil cocktail better than other caps.
The emanation bubblers for the LC method are both fragile and expensive.
Therefore, it is recommended that samples be collected in the field in 4-ounce
or larger glass bottles fitted with Poly Seal caps and that the sample bottles
be brought or sent to the laboratory for an early LC method analysis. Samples
should be collected by a positive pressure sampling technique as described in
the Appendix D procedure. An alternative positive pressure sampling technique
has been described by the Sanitation and Radiation Laboratory of the California
Health Department (Appendix E).
s
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SECTION 4
EXPERIMENTAL PROCEDURES
ANALYTICAL TEST PROCEDURES
Sampling
The sampling technique represented in this study was the collection of
water samples in 60-mL bottles capped with Poly Seal caps and shipped to the
laboratory for subsequent analysis oy liquid scintillation or by the Lucas Cell
method. There is a radon loss associated with this sampling technique. For
example, when the water sample is held in the 60-mL bottle for 4 days before
analysis and then 10-mL a1iquots are withdrawn (by a 10-mL Mohr pipette having
the tip ground off to a 1/8 inch diameter opening) and are added to liquid
scintillation vials containing 10 mL of either a detergent type or mineral oil
liquid scintillator cocktail, there is an approximate 15 percent loss of radon.
The loss is due to radon dissolving in the Poly Seal cap liner and to the
negative pressure aliquot transfer.
The analytical method for radon/water concentrations published by the EPA
(7) describes a negative pressure sampling technique. A copy of that method is
included in Appendix B. A description of a positive pressure collection of
water samples in 60-mL glass bottles for subsequent analysis for radon is given
in Appendix C (NIRS Sampling Instructions-Radon).
In this study the sampling consisted of simply transferring measured
portions of water from the standard and sample bottles (60 mL) provided to
liquid scintillation vials containing liquid scintillator cocktail for analysis
by liquid scintillation or to emanation bubblers for the transfer of the radon
from the water to Lucas Cells for counting the radon plus progeny alpha activity.
Liquid Scintillation Method
The EPA method calls for transferring 1u-mL portions of sample water with
a hypodermic syringe and needle, directly from a free-flowing, non-aerating
water tap to liquid scintillation vials containing lu-mL of mineral oil scinti-
lator cocktail, Appendix B. The vials are capped immediately with Poly Seal
caps, are shaken thoroughly to mix, and are sent back to the laboratory for
counting the radon plus progeny alpha and beta activity in a liquid scintilla-
tion counter.
6
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Lucas Cell Method
Participants in this study were referred to Method 9U3.1 in the "Prescribed
Procedures for Measurement of Radioactivity in Drinking Water," EPA-6UU/4-dU-032,
August 198U, for a description of the apparatus and the emanation steps for the
Lucas Cell method of radon/water concentration analysis. A detailed description
of that methodology for grab sample analysis of water samples is given in
Appendix D.
COLLABORATIVE TEST PRUCEDURES
Standard and Sample Solutions
Since most of the ground-water supplies that contain high concentrations
of radon show low concentrations of the radium progenitor, it was desirable to
provide radium-free radon/water standards and samples to the participants in
the multilaboratory test of the two analytical methods. Radon-222 generating
sources were prepared by evaporating known quantities of radium-226 in solution
on 2.4-cm diameter filter paper discs (Whatman 54U filter paper) and then by
sandwiching and sealing the discs in 4 mil thick polyethylene film (Ra-226/Poly
sources). The Ra-226/Poly sources were put into 60-mL glass bottles which were
then completely filled with deionized water and capped with Poly Seal caps.
Radon-222 diffuses through the source poly film.and dissolves in the water
contained in the bottle. As long as the filter paper disc in the source package
appears dry, there should be no radium-226 getting to the water in the bottle.
Such Ra-226/Poly sources were prepared for standard and sample waters for the
multilaboratory test study. Each standard and sample contained its own Ra-226/
Poly source package.
The radon/water standards sent to the participating laboratories contained
d25 pCi (some contained 832 pCi) of radium-226 in the Ra-226/Poly sources.
Radon/water samples A, B, and C that were sent to the participating laboratories
contained 102.6 pCi, 1,U36 pCi and 4,205 pCi, respectively, of radium-226. The
radon/water concentrations for those samples (A, B, and C) at full radon
ingrowth were 1,616 pCi/L, 16,321 pCi/L and 66,246 pCi/L, respectively.
General Procedures
Invitations to participate in the multi-laboratory test of the two analyti-
cal methods were sent to 45 laboratories. Forty laboratories agreed to parti-
cipate in the study. Instructions, standards, and samples were sent to the 4U
participating laboratories in November 19d6. The laboratories were instructed
to report their test results by January 15, 19d7. About one-half of the
laboratories had submitted their test results by the January 15 date. Therefore,
the study was extended to March 1, 1987. About two weeks after the March 1
termination date, a letter was sent to each participating laboratory. The letter
contained the known radon-222 concentration values for samples A. B. and C and
two tables (one for each method) of the test result averages of the laboratories.
The laboratories were not identified in those tables; rather, the data was
simply indexed by a number.
7
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DATA PROCESSING PROCEOURES
The data from the participant laboratories were tested for outliers by
the ASTM recommended criterion for rejection (ASTM, 198U). When a particular
laboratory test result was in question, the T value was calculated by Equation 1.
T1 =
(Xl - 1.)/S,
(1 )
where:
T1
= test criterion
x = arithmetic average of all n values
S = the estimate of the population standard deviation based on
the sample data.
If the T1 values exceeded the critical values, the measurement in question was
rejected. Critical values of T for a 5 percent, two-sided level of significance
were used for the reJection criterion.
A statistical evaluation of the test results was carried out by the
procedures described in E-691, E-177, and £-178 of the ASTM Standard Part 41,
1980. The standard deviations and other statistical parameters and equations
for their calculations are listed below. The standard deviation of individual
participant (or laboratory) test results, Sij, was determined by Equation 2.
S. .
1 J
[ni j
= E
h=l
- 2 ]1/2
(Xijh - Xij) /(nij - 1)
(2)
where:
Xijh
1.. .
1 J
nij
= the result reported for the h replicate of the j sample material
by lab i
= the mean of the individual results for sample j for lab i
= the number of replicates reported for sample j by lab i.
The repeatability (within-laboratory standard deviation), Sr.' for each sample
was determined by tquation 3 or 3A. J
Where the number of replicates was the same (three) for all participants,
Equation 3 was used.
Sr .
J
=
(p 2) 1/2
l/P E S..
. 1 1J
1=
(3)
where:
P
= the number of participants in the study.
Where the number of replicates was not the same for all participants,
Equation 3A was used.
d
-------
Sr.
J
=
P
E
i=l [(n1'J - 1) S. 2]
1J
P
E (ni j - 1)
i=1
1/2
(JA)
The standard deviation of the grand average for each sample. Sx.. was
determined by Equation 4. J
Sx. = ['~l (Xij - Xj)2/(P-l)]1/2
J 1=
the average of the test results for sample
(4 )
where:
X' .
1J
=
material j by lab i
Xj =
the grand average for sample material j.
The standard deviation of between-laboratory precision for each sample material.
SL.. was determined by Equation 5.
J
~ 1/2
Sr '
J
SL. = (t»
J n
The reproducibility (combined within- and between-laboratory standard devia-
tion) for each sample. SR.. was determined by [quation 6.
J SR. = (Sr.2 + SL.2) 1/2
J \ J J
The coefficient of variation for repeatability (within-laboratory) for each
sample. Vr ,%. was determined by Equation 7.
J
(6)
Vr.% = 1uu Sr./ Xj
J J
(7)
The coefficient of variation for between-laboratory precision for each sample.
VL .%. was determined by Equation 8.
J
VL.% = 100 SL./ Xj
J J
(8 )
9
-------
The coefficien~ of variation for reproducibility (combined within- and between--
~aboratory) for each sample, VR.%, was determined by Equation 9.
J
VR.% = 1Uu SR./ Xj
J J
(9)
The accuracy index, Aj%, a percent relationship of the grand average, Xj, to
the known value, Yj, for each sample material, was determined by Equation 1U.
X".
A.% - 1UU..l
J -
Yj
(10)
Bias, the difference between the known value and the measured mean value, was
determined by tquation 11.
Bias =' X". - Y
J
(11)
where:
Y
= the known value.
Percent Bias was determined by Equation 1~.
% Bias
=
X". - Y
J
Y
x 10U
(12 )
A comparison of the grand average value, Xj, with the known value, Yj, for
each sample in a significant difference test was determined by Equatl0n 13
(Youden and Steiner, 1975).
t.
J
=
X" - Y .
J J
S- /(p)1/2
x.
J
, (P-1) degrees of freedom
( 13)
where:
p
= number of participants
y.
J
= known value of the sample j contaminant concentration
tc =
critical value for the number of participants; values for tj
greater than tc are significantly different and show a
systematic error. A table of critical values is given in
the above reference.
IV
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SECTION 5
RESULTS AND DISCUSSION
Table 1 lists the test result averages, individual laboratory standard
deviations from replicate analyses, the number of replicates averaged, and the
factor (cpm/pCi) for converting counts per minute to picocuries of radon-222,
for the liquid scintillation (LS) method. Only two laboratory average outliers
were found in those test results (both for Sample B). Laboratory 21 analyzed
the samples two times by the LS method, once by using the mineral oil liquid
scintillator cocktail and once by using a detergent-type liquid scintillator
cocktail (data included in Table 1).
TaDle 2 is a statistical summary of the accuracy, bias, and precision of
the Table 1 test results, as calculated by the equations given in the Section 4,
Data Processing Procedures. A comparison of known values for Samples A, B, and
C with the grand averages of the test results for those samples shows accuracy
indexes of 94.u percent, 96.5 ~ercent, and 9~.0 percent, respectively, for an
average accuracy index of 95.2 percent t 2.u percent (95 percent confidence).
The ~5.2 percent accuracy index corresponds to a negative bias of 4.~ t 2.0
percent (95 percent confidence). The 4.8 t 2.0 percent negative bias is a'sig-
nificant (real) bias as indicated by the T values for the samples being greater
than the critical values for T. However, that bias is not a serious bias and
is likely due to a loss of radon activity in the transfer of successive aliquots
from the same sample bottle water for replicate analyses (compare Table 1 test
result averages with Table j first aliquot test results).
Table 2 shows that the estimated (20 participant average) repeatability
(within-laboratory precision) of the liquid scintillation method for the deter-
mination of radon-222/water concentrations at the l,60U pCi/L level (Sample A)
is 87 pCi/L (5.7 percent); at the 16,000 pCi/L level (Sample B) is 3d5 pCi/L
(2.5 percent); and at the 66,uuO pCi/L level (Sample C) is 1,630 pCi/L (2.6
percent), for an average repeataDility (index precision) of J.6 t 3.0 percent
at 95 percent confidence.
Table 2 shows the estimated (20 participant average) reproducibility
(combined within- and between-laboratory) precision of the liquid scintillation
method for the determination of radon-222/water concentrations at the 1,600 pCi/L
level (Sample A) is 1d9 pCi/L (12.4 percent); at the 16,OuO pCi/L level (Sample
B) is l,1S9 pCi/L (7.4 percent); and at the 66,000 pCi/L level (Sample C) is
6,8J9 pCi/L (10.9 percent), for an average reproducibility (index precision) of
10.2 t 4.2 percent at 95 percent confidence.
Table 3 was prepared to show that the first aliquot analysis is generally
higher in radon/water concentration than the averages of the replicate analyses
11
-------
of aliquots taken from the same sample bottle water. The T tests to show sig-
nificant difference applied to the Table 3 test results for Samples A. B. and C
show that the Sample A. B, and C grand averages are not significantly different
from the respective sample known values (T values for the samples are less than
the critical values).
Tables 4a and 4b were prepared to show differences between first and last
aliquot analyses for the replicate analyses of some of the laboratories where
it was obvious that they took successive aliquots from the same standard and
sample water (one-time generations in the 60-mL bottles provided). Some labora-
tories regenerated standards and samples in their analysis of the samples.
Table 5 lists the laboratory test result averages. their standard devia-
tions from replicate analyses, the number of replicates averaged. and the factor
(cpm/pCi) for converting counts per minute to picocuries of radon-222. for the
Lucas Cell (LC) method. No outliers were found in the Table 5 test result
averages.
Table 6 is a statistical summary of the accuracy. bias, and precision of
the Table 5 test results. as calculated by the equations given in the Section 4.
Data Processing Procedures. A comparison of the known values for Samples A, B,
and C with the respective grand averages of the Table 5 test results shows
accuracy indexes of 101.~ ~ercent, 102.7 percent, and ~7.4 percent, respectively.
for an average accuracy index of 100.7 t 4.6 percent at ~5 percent confidence.
The bias values of +1.9 percent, +2.7 percent, and -2.6 percent for Samples A,
B, and C, respectively, are within the 95 percent confidence limits of the
average accuracy index. The T tests to show significant difference applied to
known values and grand averages for the samples show that there are no signifi-
cant differences (T values for the samples are less than the critical value).
Table 6 shows that the estimated (12 laboratory average) repeatability
(within-laboratory precision) of the Lucas Cell method for the determination of
radon-222/water concentrations at the 1,600 pCi/L level (Sample A) is 94 pCi/L
(5.7 percent); at the 16,000 pCi/L level (Sample 8) is 776 pCi/L (4.6 percent);
and at the 66,0UU pCi/L level (Sample C) is 5,7~2 pCi/L (9.U percent), for an
average repeatability (index precision) of 6.4 t 3.8 percent at ~5 percent
confidence.
Table 6 shows that the estimated (12 participant average) reproducibility
(combined within- and between-laboratory precision) of the Lucas Cell method for
the determination of radon-222/water concentrations at the 1,600 pCi/L level
(Sample A) is 276 pCi/L (16.8 percent); at the 16.00U pCi/L level (Sample B) is
2,592 pCi/L (lS.5 percent); and at the 66,UOO pCi/L level (Sample C) is lJ.2UU
pCi/L (20.5 percent), for an average reproducibility (index precision) of 17.6
t 4.2 percent at 95 percent confidence.
12
-------
TABLE 1.
LIQUID SCINTILLATION METHOD
================================================================================
Radon-222 pCi/1.UUu g :t S
Labora- Factor Replicates
tory cpm/pCi :t S Sample A Sample B Sample C (n)
1 8.8~ :t O.OU 1.571 :t 31 16.30~ :t 46 67.076 :t 3u ,
2 8.25 :t 0.23 1.57U:t 31 16.U65:t 23~ 65.797 :t 1.16U 6
3 7.26 :t 0.19 1,599 :t 7S lS,4u4 :t 293 50,934 :t 7SlI 4
4 8.45 :t 9.U5 l,568:t 8 16,270 :t 33 S1,916 :t 130 2
6 8.13 :t 0.34 1.2~3:t ~2 16,966:t 419 67,666 :t 1,U14 3
7 7.50:t 0.23 1,656:t 62 16,734:t 237 68,432 :t 1,416 5
10 8.59 :t v.06 1,501 :t 11 14,943:t 1.112 61,u2U:t 660 ,
11 7.51 :t 0.45 1,358 :t 78 (1O.387:t 646}b 68.366 :t 309 3
13 6.75 :t 0.08 1,671:t 33 16,916 :t 174 55,733 :t 1,~78 3
15a 7. 7u :t u.17 1,6u4:t 152 16,548:t 487 4~,940 :t 2,543 6
17 8.JO :t 0.49 1.280:t 20 17 . u6U :t llu 52,OSLI :t 1,140 2
18 8.40 :t 0.08 l,629:t 18 15,158 :t 166 65,862 :t 295 3
18 8.12 :t 0.37 1,568:t 97 14,722 :t 581 63,341 :t 3,22L1 6
20 8.0~ :t 0.10 1,828:t 33 12.968 :t 362 76.640 :t 13, 3
21 8.19 :t O.OS 1.614:t 22 16,660:t 157 69,421 :t ,50 3
21a 9.12:t 0.U9 1,567 :t 28 15.30U:t 229 60,920 :t 627 3
23 6.82 :t 0.Ll03 l,5S6:t 30 lS,281:t 256 6S,37S :t 1,Ll39 2
26 9.00 :t 0.09 1,553:t 31 15,92U :t 360 66,56L1 :t 62S 3
27 3.64 1,29L1 14,200 60,700 1
27 3.34 :t 0.47 1,117 :t 3U9 (9,804:t 5,665)b 66.141 :t 1.380 2
X :t S)t 1,:>2L1 :t 170 lS , 800 :t 1,lU(J 62,900 :t 6,600
Known 1,620 :t 4~ 16,300 :t Sol. 66.,UO :t 2,Ll30
Value
(Y)
================================================================================
aDetergent liquid scintillator was used instead of mineral oil liquid
scintillator.
bOutlier not used in the grand average.
13
-------
TABLE 2. LIQUID SCINTILLATION METHOD
(Accuracy. Bias, and Precision Summary)
===============================================================================
Parametera Sample A Sampl e B Sample C
y. (pCi/L) 1620 :!: 49 16,300 :!: 5L11 66,200 :!: 2,034
J
X. (pCi/L) lS20 15,700 62,900
J
A' (%) 94.0 96.5 9S.0
J
Bias (%)b -6.0 -3.5 -5.0
SXj (pCi/L) 169 1, lULl 6,6S0
Srj (pCi/L) 87 3tiS 1,630
SLj (pCi/L) 168 1,Ll9L1 6,640
SRj (pCi/L) 190 1,200 6,840
Vrj (%) S.7 2.5 2.6
VLj (%) 11.1 7.u 1O.!:)
VRj (%) 12.4 7.4 10.9
T .-1c 2.56 2.a 2.a
J
T-3 1.44 U.35 2.U1
J
Average
% Values:!: S
95.2 :!: 1.0
-4 . 8 :!: 1. U
3.6 :!: lob
9.~ :!: 1.9
10.2 :!: 2.1
------------------------------------------------------------------------------
------------------------------------------------------------------------------
aparameters are described in the text.
bThe sign before the number indicates the direction of bias.
cThe critical value (tc) for significant difference at the 5
cance level for 18 laDs (Sample B) is 2.105 and for 20 labs
i s 2.090.
Tj-l values are calculated from TaDle 1 test results.
Tj-3 values are calculated from Table 3 test results.
14
percent signifi-
(Samples A and C)
-------
TABLE 3. LI QU I D SCINTILLATION METHOD
(First Aliquot Test Results)
===============================================================================
Radon pCi/l,QOO g :t S
Factor
Laboratory cpm/pCi Sample A Sample B Sample C
1 8.8tl 1,540 16,3S4 67,106
2 8.46 1, 6u 1 16,146 66,073
3 7.46 1,719 15,768 59,911
4 8.40 1,560 16,237 52,046
6 8.30 1,360 17,400 69,100
7 7.68 1,618 16,473 67,839
10 8.66 1,513 16,055 61,680
11 8.U2 1, 4S U (9,930)a 68,lUO
13 6.84 1,686 16,798 S8 ,271
15 7.80 1,746 16,9d5 51,8tl4
17 8.68 1,260 16,950 53,190
Itl 8.46 1,604 15,309 66,102
2U 8.21 1,8"13 13,459 74,67U
21 8.2S 1,63U 16,854 69,605
21 9.25 1,582 15,616 61,783
23 0.82 1,586 15,025 64,336
26 9.11 1,553 15,920 66,910
27 3.64 1,29U 14,200 60,70U
X 1,560 16,UOO 63,3UO
Sx 150 998 6,227.
Y 1,620 :t 49 16,300 :t 501 66,£00 :t 2030
T 1.44 0.35 2.01
-------------------------------------------------------------------------------
-------------------------------------------------------------------------------
aOutlier not used in the grand average.
15
-------
TABLE 4a. LIQUID SCINTILLATION METHOD
(Test Results of First and Last A1iquots)
=============================================================
Replicate
Laboratory Analyses First Last First Last
2 6 8.46 7.95 1,601 1,538
3 4 7.46 6.95 1,719 1,60~
6 3 8.43 7.65 1,360 1,17u
15 6 7.80 7.40 1,746 1,462
18 6 8.46 7.41 1,604 1,392
21 6 8.25 7.52 1,629 1,414
21a 6 9.25 7.95 1,582 985
-------------------------------------------------------------
-------------------------------------------------------------
aDetergent type liquid scintillator cocktail was used; all
others used mineral oil liquid scintillator cocktail.
TABLE 4b. LIQUID SCINTILLATION METHOD
(Test Results of First and Last Aliquots)
-------------------------------------------------------------------
-------------------------------------------------------------------
Replicate
LaDoratory Analyses First Last First Last
2 6 16,146 15,708 66,073 63,~37
3 4 1S,769 15,102 59,911 58,501
6 3 17 ,40U 16,400 69,100 66,900
15 6 16,986 15,728 51,884 45,012
18 6 15,309 13,602 66,102 56,850
21 6 16,854 14,668 69,605 63,41L1
21a 6 15,616 12,517 61,783 53,314
===================================================================
aDetergent type liquid scintillator cocktail was used; all others
used mineral oil liquid scintillator cocktail.
16
-------
TABLE 5.
LUCAS CELL METHOD
===============================================================================
Labora-
tory
Factor
cpm/pCi t S
Radon-222 pCi/1,000 9 t S
Sample A
Sample B
Sample C
Replicates
(n)
5
8
12
14
16
17
19
21
22
24
25
28
r
$-
x
Known
Value
(Y)
3.79 t .08
4.24 t .U4
2.50 t .04
4.78 t .13
4.89 t .04
4.67 t .~l
4.66 t .15
4.57 t .24
lob3 t .13
0.1053
1,838 t 96 17,450 t 815 72,280 t 12,418
1,608 t 26 14,514 t 72 45,730 t 392
1,552 17,55U 60,780
1,702 t 93 16,493 t 1,452 73,921 t 2,604
1,510 t 84 16,746 t 935 6:>,854 t 2,510
1,495 t 265 16,950 t 300 49.200 t 5~0
1,636 t 60 16,680 t 827 67,756 t 2,459
1,586 t 68 16,466 t 277 66,197 t 1,445
13,537 t 379
2,059 t 81 19,690 t 580 79,670 t 5.752
1,550 t 8:> 19,257 t 1':l2 77, 90U t 2,339
2,100 t 200 21,000 t 2,000 70,000 t 7,000
1,6bU 16.80U 64,50U
261 2.480 12,OOU
1,620 t 49
16.300 t 501
66,200 t 2.030
5
2
1
3
6
2
6
3
5
5
2
1
===============================================================================
17
-------
TABLE 6. LUCAS CELL METHOD
(Accuracy, Bias, and Precision Summary)
===============================================================================
Parametera Sample A Sample B Sample C
y. (pCi/L) 1,620 t 49 16,300 t 5U1 66,200 t 2,03u
J
1. (pCi/L) 1,650 16,800 64,500
J
Aj (%) 101. 9 102.7 97.4
Bias (%)b +1.9 +2.7 -2.6
Sxj (pCi/L) 261 2,4tiO 12,UOU
Sr j (pCi/L) 94 776 5,7'jU
SLj (pCi/L) 2t>9 2,47U 11,900
SRj (pCi/L) 276 2,590 13,200
Vrj (%) 5.7 4.6 9.0
VLj (%) 15.7 14.8 18.4
V Rj (%) 16.8 15.5 20.5
T.c 0.411 0.624 0.498
J
Average
% Values t S
lOU.7 t 2.;)
6.4 t 1.9
16.3 :t 1.5
17.6t2.1
------------------------------------------------------------------------------
------------------------------------------------------------------------------
aparameters are described in the text.
bThe sign before the number indicates the direction of bias.
cThe critical value (Tc) for significant difference at the 5 percent signifi-
cance level for 12 laDS (Sample B) is 2.18 and for 11 labs (Samples A and C)
is 2.20.
1ti
-------
REFERENCES
1.
Patridge, J. E., T. R. Horton, and E. L. Sensintaffar, A Study of Radon-
222 Released from Water During Typical Household Activities, ORP/EERF-
79-1 March 1979, Eastern Environmental Radiation Facility, Montgomery,
Alabama.
2.
Smith, B. M.. W. N. Grane, F. B. Higgins, Jr.. and J. G. Terrill, Jr..
Natural Radioactivity in Ground Water Supplies in Maine and New
Hampshire. Journal American Water Works Association, Vol. SJ, No.1
January 1961, pp. 7S-~8.
3.
Aldrich, L. K., III, M. K. Sasser, and D. A. Conners, IV, Evaluation of
Radon Concentrations in North Carolina Ground Water Supplies, Dept. of
Human Resources, Division of Facility Services, Radiation Protection Branch,
Raleigh, North Carolina, January 1975.
4.
O'Connell, M. F., and R. F. Kaufman, Radioactivity Associated with Geothermal
Waters in the Western United States, U.S. Environmental Protection Agency
Technical Note, ORP/LV-7b-8A, March 1976.
5.
Duncan, D. L., T. F. Gesell, and R. H. Johnson, Jr., Radon-222 in Potable
Water, Proceedings of the Health Physics Society 10th Midyear Topical
Symposium: Natural Radioactivity in Manis Environment, October 1976.
Hutchinson, J.M.R., R. A. Mullen and R. Colle~ Development of a
Regenerative Radon-In-Water Radioactivity ~tandard, National Bureau
of Standards, Washington, D.C., USA.
6.
7.
EPA/EERF - Manual-78-1 Radon in Water Sampling Program.
19
-------
APPENDIX A
PARTICIPANT LABORATORIES
(NOT LISTED IN ORDER OF TABLE LABORATORY NUMBERING)
North Carolina State Laboratory
of Publ ic Health
Department of Human Resources
Raleigh, North Carolina
Argonne National Laboratory
Argonne, 111inois
Air-N-So1 Corporation
Frenchtown, New Jersey
U.S. Environmental Protection Agency
Environmental Montoring Systems
Laboratory
Cincinnati, Ohio
State of Connecticut Health
Laboratory
Hartford, Connecticut
State of California
Department of Health Services
Berkeley, California
Atlantic Environmental Laboratory
West Haven, Connecticut
U.S. EPA Eastern Environmental
Radiation Facility
Montgomery, Alabama
New Hampshire Water Supply and
Pollution Control Commission
Concord, New Hampshire
Texas Department of Health
Austin, Texas
Kentucky Radiation Control
Branch Laboratory
Commonwealth of Kentucky
Frankfort, Kentucky
Clean Harbors, Inc.
Braintree, Massachusetts
Environmental Laboratories, Inc.
Gu1fport, Mississippi
Radiological Hygiene Laboratory
Department of Environmental Science
and Engineering
University of North Carolina
Chapel Hill, North Carolina
U.S. EPA - Region VIII
Denver Federal Bldg.
Denver, Colorado
USAF Occupational and Environmental
Health Laboratory
Brooks Air Force Base, Texas
USGS - Gulf Coast Hydroscience
National Space Technology
Laboratories
NSTL, Mississippi
Center
Maine Public Health Laboratory
Stat ion 12
Augusta, Maine
20
-------
Oak Ridge Associated Universities -
RSAP
Oak Ridge, Tennessee
Wisconsin State Laboratory of Hygiene
Madison, Wisconsin
Thermo Analytical Inc. - EAL
Richmond, California
New York State Department of Health
Radiological Sciences Laboratory
Albany, New York
Kutzman University
Department of Physical Sciences
Kutztown, Pennsylvania
Teledyne Isotopes
Westwood, New Jersey
Kansas Department of
Environment
Radiation Laboratory
Topeka, Kansas
Health and
University of Maine
Department of Physics
Orono, Maine
New Jersey Department of Environmental
Protection
Bureau of Environmental Laboratories
Trenton, New Jersey
Radiation Surveys, Inc.
Wayne, New Jersey
Colorado State University
Department of Radiology and
Biology
Fort Collins, Colorado
Radiation
21
-------
L-. --~- .
APPENDIX B
ANAL YTICAL TEST PROCEDURE "THE DETERMINATION OF RADON IN DRINKING WATER"
(EPA EASTERN ENVIRONMENTAL
RESEARCH FACILITY, MONTGOMERY, ALABAMA)
THE DETERMINATION OF RADON IN DRINKING WATER
There are several pUblished methods for the determination of radon
(Rn-222). Those include de-emanation into a scintillation flask or Lucas Cell,
gamma spectrometry, high volume extraction followed by liquid scintillation
counting, and direct low-volume liquid scintillation counting.
Of the aforementioned methods, the last one is probably the most rapid and
simplest while other methods may exhibit higher sensitivity. Good precision
and accuracy have been shown for samples having radon concentrations of several
hundred pCi/L or greater using direct, low-volume liquid scintillation
counting. It is especially suited for large numbers of samples over a short
period of time. For reasons previously stated, direct low volume scintillation
counting is the recommended procedure for determining radon in drinking water,
since high sensitivity (e.g., 1 pCi/L or less) is not necessary.
Principle
Samples are collected using the sampling procedure described in
EPA/EERF-MANUAL-78-1. Samples are counted by liquid scintillation counting and
radon concentration is computed from total count rate due to alpha and beta
decay.
Special Apparatus
1.
Sampling kit which includes a sampling funnel and tube with standard
faucet fitting, two 12 mL disposable syringes with 20 gauge
1-1/2 inch hypodermic needles, and glass scintillation vials with 10
mL of liquid scintillation mix. See Note 1.
Optional mailing tubes.
Liquid scintillation counter, ambient temperature, with
automatic sample changer.
2.
3.
22
-------
Reagents
Procedure
1.
Mineral oil based liquid scintillation mix PSS-QU7H or equivalent,
if mailing via regular mail. Otherwise, a toluene based liquid
scintillation mix is acceptable. See Note 2. .
Distilled water.
A traceable National Bureau of Standards (NBS) radium-226 standard
solution.
2.
3.
1.
2.
Attach the sampling funnel and tube to a faucet with the standard
faucet fitting.
Slowly turn on the water and allow a steady stream to flow out of the
funnel for approximately 2 minutes. This purges the tube and assures
a fresh sample.
Reduce the flow of water and invert the funnel. The flow should be
adjusted to a level that does not cause turbulence in the pool of
water contained in the funnel. Allow excess water to spillover one
edge of the funnel.
Examine the hose connection and tubing for air bubbles or pockets.
If these are visible, raise or lower the funnel until they are
removed.
Place the tip of the hypodermic needle approximately 3 cm under the
surface of the water in the funnel and withdraw a few mL of water
and eject this water. Using this procedure, rinse the syringe and
hypodermic needle two or three more times.
Again, place the tip of the needle approximately J cm below the
surface of the water and withdraw approximately 12 mL.
3.
4.
5.
6.
NOTE:
The water should be pulled into the syringe slowly to avoid
extreme turbulence and collection of air bubbles. If
large air bubbles are noticed in the syringe, the sample
should be ejected and redrawn.
7.
8.
Invert the syringe and slowly eject any small air bubbles and extra
water. Retain precisely 10 mL of water in the syringe.
Remove the cap from a vial and carefully place the tip of the needle
into t~e bottom of the liquid scintillation solution. Slowly eject
the water from the syringe into the vial.
NOTE:
The water is injected under the liquid scintillation solution
to prevent loss of radon from the sample. If the water
is forced out of the syringe with much pressure. it will cause
turbulence in the solution and could result in loss of radon.
9.
Carefully withdraw the hypodermic needle from the vial and replace
the cap. The cap should be tightly secured to prevent leakage.
Repeat the previous steps to obtain two separate samples from each
source. This completes the sample collection.
10.
23
-------
11.
If the vials are to be mailed, the two samples from each source
should be individually wrapped with packing material such as
newspaper or paper toweling, placed in the mailing tube, and
mailed as soon as possible. Due to the short half-life of radon
(3.82 days), the quick return of the samples for analysis is of
primary importance.
Counting Procedure
1.
2.
Scintillation vials are cleaned with alcohol and shaken while
allowing 3 hours before counting.
A background sample, consisting of 10 mL of distilled water and
10 mL of scintillation solution, and a standard radium-226
solution sample are counted for 50 minutes at the beginning of
counting and after every 10 drinking water samples. Drinking
water samples are also counted for 50 minutes.
An optional second counting of samples is desirable.
3.
Preparation of Standard
Calculations
1.
Add a known quantity of traceable NBS radium-226 standard solution
to a known volume of distilled water.
Combine a 1U mL aliquot of the radium-£26 standard solution with
10 mL of scintillation mix in a 20 mL glass scintillation vial.
Allow approximately 21 days for buildup of radon (i.e., secular
equilibrium with radium-226).
Shake vial to transfer nearly all the radon to the scintillation
mix phase (radon is highly soluble in the scintillation mix).
The radium-226 remains in the aqueous phase and, therefore, does
not contribute significantly to the count rate.
Allow the buildup of the radon short-lived progeny by waiting
3 hours before counting.
Count the standard and background samples for 50 minutes or longer.
Subtract the background counts per minute (cpm) from the gross cpm
for the standard and divide by the known radon activity (i.e., radon
activity equals radium-226 activity at secular equilibrium) to obtain
the cpm/pCi conversion factor.
2.
3.
4.
5.
6.
7.
Calculate the picocuries per liter of radon in the sample by using
the following equation:
A =
(CS - CB) (lUOO mL)
(CF) (D) (10 mL) (1 liter)
where:
A = picocuries of radon per liter of, sample
Cs = sample CQm
CB = backgrou~d cpm
CF = cpm/pCi conversion factor
D = Decay correction.
24
-------
Decay Correction:
Decay correction (D) = e
O.693(T)
t1/2
T = Time in days from collection time to midpoint of
counting time.
t1/2 = Radiological half-life of radon, 3.82 days.
Notes
1.
Liquid scintillation vials are standard 20 mL capacity. White caps
having polyethylene inner seals are used.
PSS-007H is available from Pilot Chemicals Division, New England
Nuclear, Watertown, MA 02172. Do not use a scintillation mix
containing emulsifier.
2.
References
1.
2.
Homma, Y. and Murakami, Y., 1977, J. Radioanalyt. Chern. 36, 177.
Horton, T. R., 1983, "Methods and Results of EPAls Studyof Radon in
Drinking Water," EPA 52U/5-83-027.
Lucas, H. F., 1957, "Improved Low-Level Alpha-Scintillation Counter
for Radon," Rev. Sci. Inst. 28, 680.
Lucas, H. F., 1964, "A Fast and Accurate Survey Technique for Both
Radon-222 and Radium-226," in The Natural Radiation Environment,
U. of Chicago Press. 315.
Noguchi. M.. 1964, Radioisotopes 13. 362 (in Japanese).
Prichard, H. M. and Gesell, T. F.:-1977, "Rapid Measurements of Rn-222
Concentrations in Water with a Commercial Liquid Scintillation
Counter." Health Phys. 33, 577.
U.S. Environmental Protection Agency, 1978, "Radon in Water Sampling
Program." EPA/EERF-MANUAL-78-1.
3.
4.
5.
6.
7.
25
-------
APPENDIX C
NIRS SAMPLING INSTRUCTIONS - RADON
(
1. R8don sampling equipment - 60 mL amber bonles,
Teflon septa, caps, universal faucet connector with
Tygon tu"ing, and labels.
-....,..
2. Fill out label with spraal pen (enclosed) and attach to
bonle before sampling.
~
~#t\Io"
~~
~~
r-
~'i;
:~
3. Anach tubing to faucet and allow
water to run for 3 min., then adjust
for slow flow.
6. Slowly remove tube allowing a
miniscus to form.
4. Remove cap with septum in place and
insert tube to bonom of bonle.
"'-
7. Replace the cap with the Teflan
septum (shiny side) in contact with
the water sample.
26
5. Slowly fill bonle to top while keeping
end of tUbe submerged.
.
!
,\\" )
- ~\. (~
8. Screw cap on tightly, invert and tap
side to check for bubbles. If found,
repeat steps 4 thru 8.
-------
APPENDIX D
ANALYTICAL TEST PROCEDURE "RADON/WATER CONCENTRATION ANALYSIS OF
GRAB SAMPLES USING LUCAS SCINTILLATION CELL DETECTORS"
SAMPLE COLLECTION
Since the radon emanation bubblers (Figure 2) are both fragile and
expensive, instead of collecting samples directly in the bubblers it is
recommended that grab samples be collected in glass bottles and brought to
the laboratory for early analysis using the Figure 1 apparatus.
Sampling Procedure
1.
The water faucet from which grab samples are to be taken should be a
non-aerating faucet. Remove the aerating attachment if one is attached
and can be removed.
2.
Attach a universal faucet hose attachment that has been provided with
approximately two feet of Tygon tubing (1/4 inch inside diameter and
1116 inch wall thickness).
3.
Open the faucet to a fast flow (not splashing) and allow water to flow
for 3 mi nutes.
4.
Stop the water flow only long enough to place the outlet end of the Tygon
tubing at the inside bottom of a sample bottle. Turn the water on care-
fully and with minimal turbulence fill the bottle completely, withdrawing
the Tygon tubing and keeping the outlet end of the tubing below the
surface of the water as the bottle fills. Turn off the water and cap the
bottle immediately.
Label the bottle to show location of sampling, the date and time of day
and the sample number.
5.
6.
If more than one sample is to be taken, open the faucet and allow fast
flow for 1 minute. Then repeat Step 4 with a separate sample bottle.
Send the sample bottles to the laboratory for early radon/water concen-
tration analyses.
7.
MATERIALS NEtDED
1.
Sample bottles (see Note 2)
27
-------
..
Scintillation Cell
..
Stopcock #3
Stopcock #4
..
Manometer, 1 Y2mm,I.D.
..
Anhydrous
Magnesium Perchlorate
Ascarite (8-20 mesh)
,"
..
Stppcock # 2
Helium (from Regulator)
~
Stopcock # 1
Radon Bubbler
...
Mercury Reservoir
Fi gure 1.
Radon emanation apparatus with scintillation cell.
28
-------
Liquid /"
level
135mm
....
17mm
~.
O.D.
~
33mm
,
~35~
mm
Figure 2.
Corning No.2
or Equivalent
Bubble Trap
7mm LD.
Rigidity Brace
7mm Capillary Tubing
1Y2mm LD. .
Fritted Glass Disc
1 0-1 5 micron pores
Volume to be kept
at minimum
A typical radon bubbler.
29
-------
2.
Universal faucet/hose attachment, provided with approximately 2 feet
of Tygon tubing (1/4 inch inside diameter and 1/16 inch wall thickness).
3. Figure 1 apparatus components
4. At least 10 Lucas scintillation cell detectors
5. At least 10 radon gas bubblers
6.
7.
8.
Vacuum pump
Lucas scintillation cell counting instrument that will accept the Lucas
cells in a light-free placement
Compressed helium or aged air cylinder with a two-stage pressure
regulator, a shutoff valve, and a hose bib attached.
For a 14 mL/minute He gas flow, attach a 10-inch length of thermometer
capillary tubing to the hose bib of the regulator and a length of 1/4 inch
diameter Tygon tube from the capillary tube outlet to the radon bubbler
inlet. Adjust the regulator pressure to 10 psi.
CALIBRATION OF LUCAS CELLS
1.
2.
Each Lucas Cell should be checked for background alpha activity before
it is used for standards or samples.
a.
Attach the Lucas cell to the emanation system.
Put a clean and dry bubbler in the system.
b.
c.
Evacuate the system including the Lucas cell.
Charge the system with He gas to atmospheric pressure.
d.
e.
Repeat the evacuation and He charging two more times, finally
leaving the cell charged with He to atmospheric pressure.
Remove the Lucas Cell from the emanation system, place the cell in the
scintillation counting system and count for alpha activity for a least
1 hour.
f.
~repare a standard radon bubbler (Figure 2) as follows:
a.
Use a clean dry radon bubbler.
b.
Lubricate the two stopcocks sparingly with silicone stopcock grease
(excess grease will block the stopcock passages). Open the bubbler
at the 1U/30 standard taper joint.
Add four drops of Photoflo or other non-foaming wetting agent to the
fritted glass disc of the radon bubbler to pre-wet the disc.
c.
30
-------
3.
4.
5.
6.
7.
8.
d.
Close the gas inlet stopcock of the bubbler and add 10 mL of distilled
or deionized water to the bubbler.
e.
Spike the bubbler water with a known quantity of radium-226 (100 p Ci
range) .
f.
Close the bubbler at the 10/30 standard taper (SIT) joint (lubri-
cated sparingly with silicone grease).
g.
Attach the He gas source to the bubbler inlet. Open bubbler
inlet and outlet stopcocks and adjust the He gas pressure to 10 psi
(through the capillary tube for 14 mLlmin gas flow).
Flush the radon from the spiked water standard for 30 minutes at
14 mL/min.
h.
1.
Shut off the He gas purge, close inlet and outlet stopcocks of the
bubbler, and record the data and time of day for the beginning of
radon ingrowth.
j.
Allow the radon to ingrow for one week or longer.
Attach the standard radon bubbler to the emanation apparatus (Figure 2),
leaving the bubbler stopcocks closed (stopcock 1 and 2 of Figure 2).
Evacuate the emanation system by opening stopcocks 3 and 4 to the vacuum
source (stopcocks 1 and 2 should still be closed).
Check the system for leaks by turning stopcock 4 to close off the vacuum
source but still open between the manometer and the emanation system
(stopcocks 1 and 2 should still be closed). Read the pressure on the
manometer. If the system does not leak more than 1 cm on the manometer
in 30 minutes, the system can be considered leak-free enough to proceed
with radon emanation from the standard radon bubbler.
The approximate volume of the Lucas Cell should be known. Using the
volume of the Lucas Cell calculate how many minutes of 14 mL/min. He gas
emanation of the bubbler will be needed to satisfy the volume of the Lucas
Cell at one atmosphere of pressure. For 314 of the emanation time the
manometer will be isolated from the emanation system and for the last 1/4
of emanation time the manometer will be part of the emanation system.
Turn stopcock 4 to close off the manometer and the vacuum source from
the emanation system. Record the date and time of day as the end of
radon ingrowth. Then very carefully open stopcock 2 to allow the
pressure of the bubbler and the emanation system to come to equilibrium
(bubbles in the radium water subside as equilibrium is reached).
Then open stopcock 1 to allow He gas to flush through the water. Regulator
should be set at 10 psi and He should be passing through a 10-inch length
of thermometer capillary tubing.
31
-------
9.
When 3/4 of the emanation time has passed, close the Lucas Cell stopcock 3
(Figure 1) and turn stopcock 4 to open the manometer (but not the vacuum)
to the emanation system, then open the Lucas Cell stopcock again, and
observe the manometer pressure. As the system approaches atmospheric
pressure or a few millimeters before, close the Lucas Cell stopcock, close
stopcocks 1, 2 and 4, and turn off the He gas at the cylinder regulator.
Remove the Lucas Cell from the emanation system, and after 4-hours
or more delay, place the Lucas Cell in the scintillation counting system
and count the alpha activity. Record the time between the end of
radon ingrowth and the mid-point of the alpha count as the decay time
to be corrected for radon decay.
10.
11.
After recording the alpha counts the
to the emanation system with a clean
the system. Purge the Lucas Cell as
cell alpha background.
Calculations - Determine the factor cpm/pCi for each cell and label each
cell with that factor.
Lucas Cell should soon be returned
and dry bubbler also attached to
desired in Step 1 and re-count for
12.
net cpm x decay factor
net cpm x e t2
= cpm/pCi
=
Ra-226 pCi
Ra-226 pCi
(1 - e- \)
x radon ingrowth factor
x
where:
t1 = Radon ingrowth time in days
t2 = Radon decay time in days
0.693
0.693
=
= 0.1814d-1
= -
T1/2 days
3.82
Tl/2 = half life of Radon-222 is 3.82 days.
SAMPLE ANALYSIS PROCEDURE
1.
Prepare a sample radon bubbler (Figure 2) as follows:
a.
Use a clean dry radon bubbler.
Lubricate the two stopcocks and the 10/30 SIT connection sparingly
with silicone stopcock grease (excess grease will block the stop-
cock passage).
b.
c.
Close both stopcocks and open the bubbler and at the 10/30 SIT
connection.
d.
Add four drops of Photoflo or other non-foaming wetting agent
to the fritted disc of the radon bubbler to pre-wet the disc.
32
-------
e.
Transfer a 10.0 mL aliquot of the water sample from the sample bottle
to the radon bubbler. Close the bubbler immediately and attach
it to the radon emanation system. Attach the He source to the gas
inlet of the bubbler. The bubbler stopcocks (1 and 2 in Figure 1)
should be closed at this time.
2.
Proceed with Step 4 in the Calibration Section and continue through
Step 11.
3.
Calculations
net cpm x decay factor x
1000 mL/L
10 mL
= pCi/L
cpm/pCi
where:
net cpm
decay factor
cpm/pCi
pCi/L
= gross cpm for 10 mL aliquot-background cpm
= e At, a number greater than unity
= factor determined from calibration of each
scintillation cell
= picocuries per liter of water sample.
33
-------
APPENDIX E
State of California
Department of Health Services
Berkeley, California
RADON SAMPLING
(SEB/SRL)
SAMPLI NG KIT
1.
2.
3.
4.
Small plastic bucket
Tygon tubing with faucet fitting
4 oz. glass prescription bottles with caps
SRL Radiological Analysis Forms and Labels
bottle
- one for each sample
SAMPLING PROCEDURE
1.
Attach Tygon tubing to faucet and direct delivery end to the bottom
of the bucket. Slowly run the water into the bucket for approximately
5 minutes. Discard the water in the bucket at least once and allow
the water to overflow during the remainder of the sampling.
2.
Remove the prescription bottle cap and by hand, with the bottle in
an upright position, carefully submerge the bottle and cap. Avoid
agitating the water and minimize creation of bubbles. With the bottle
under water, insert the end of the tubing into the bottle and allow
the water to exchange to assure a fresh sample. Cap the bottle tightly
while they are both under water.
3.
After removing the capped bottle from the bucket, invert the bottle
and check to see if any bubbles are present. If bubbles are present,
empty the bottle and re-sample beginning with Step 2. However, in
order to obtain duplicate samples representative of the same source,
one must repeat Steps 1-3 above. Ordinarily, duplicates are taken at
a frequency of at least one per every tenth sample but may be taken at
a greater frequency depending upon program needs.
4.
Wipe bottles thoroughly and attach an identification label to each
dried bottle. Fill in the SRL Radiological Analysis Form completely.
Note carefully that, because of the short half-life of radon (3.8
days), it is essential that date and time of collection be exact.
34
-------
5.
Return the samples to the laboratory as soon as possible, preferably
by overnight mail or courier.
SRL (1/23/87)
35
-------
APPENDIX F
INSTRUCTIONS TO PARTICIPANT LABORATORIES
October 29, 1986
Dear Colleague:
The following information and instructions are given for the multilaboratory
test of two methods for Radon-222 (Rn-222) in water. In the letter, to which
you responded, I described two types of water that are naturally occurring and
contain Radon-22 (Rn-222). I planned at that time to include samples
representing both types of water. However, since radium-226 (Ra-226) has its
own concern and has been addressed extensively, I will use only the second type
of water, one in which the radon-222 baring water is removed from its parent
source.
Because of the short half life of Radon-222 and the relatively long transit
times in shipping samples across the country, I have prepared standards and
samples that contain their own sealed Ra-226/Rn-222 generating source. The
source package is simply a 2.4 cm diameter filter paper on which a known amount
of Ra-226 standard solution has been evaporated and air dried, and then sand-
wiched and sealed between two pieces of polyethylene film (5 mil). Radon-222
ingrown from the Ra-226 will transfer through the polyfilm to the water in
which the source package is contained. As long as the filter paper in the
package remains dry, there should be no Ra-226 getting to the water. A
distinct advantage of these standards and samples is that new standard and
sample Rn-222 source water can be made by simply changing the water in the
bottle and allowing for another ingrowth of Rn-222.
36
-------
For Rn-222 in-water standards using this type of Ra-226/Rn-222 generating
~ource, it is important to know the transfer factor for Rn-222 getting to the
water in which the source package is contained. In an experiment to determine
the transfer factor 5 Ra-226/Rn-222 source packages were prepared by the
techniques described above. Those 5 source packages were put into 60 ml glass
bottles. To 5 other 60 ml glass bottles was added the same amount of Ra-226
activity (an aqueous solution) as was used for the 5 source packages. All 10
bottles were completely filled witn deionized water and capped with Poly Seal
caps. After an ingrowth period of 7 days, 10 ml aliquots of each bottle were
analyzed for Rn-222 by the oil based liquid scintillator method. A comparison
of the average cpm/pCi for the two sets of bottles showed the transfer factor
to be 96.1$ + 3.4$ at 95$ confidence. This transfer factor is valid for
standard and-sample source packages that have been prepared as described above
and have been contained in water in glass bottles with 20 mm Poly Seal caps.
If these source packages were contained in water in glass bottles with another
type of cap the transfer factor may be slightly different because it includes a
small Rn-222 loss factor that is characteristic of each type of cap (the cap
liner being the differentiating componen~).
I am sending one standard Ra-226/Rn-222 source and three sample Ra-226/Rn-222
sources to each participant. The Ra-226 activity of the standard Ra-226/Rn-222
source is listed on the standard bottle. The standard and sample source pack-
ages have been placed in 60 ml bottles, then completely filled with deionized
water and capped with Poly Seal caps. Since Rn-222 will be ingrowing and
transferring to the water in each bottle, the start of ingrowth is marked on
each bottle. To report the Rn-222 concentration of the water samples you will
need to know the total sample water content in each bottle. The total sample
water weight is marked on each bottle.
By sending you this type of samples. I am modifying the sampling end of the
commonly used liquid scintillation method. the modification being, collecting a
full glass bottle of water from a free-flow non-aerating water tap. capping the
bottle with a Poly Seal cap and sending it to the laboratory for analysis. In
the commonly used liquid scintillation method. 10 ml portions of water from a
free-flowing, non-aerating water tap are taken by a hypodermic syringe and
added to liquid scintillation vials containing 10 ml of oil based liquid
scintillator solution and shaken vigorously to extract the larger portion of
the Rn-222 into the oil phase of the system. The vials are then taken or
shipped to the laboratory for counting the Rn-222 activity. The significance
of this modification of the sampling end of the liquid scintillation method may
need to be addressed in a separate study.
The Rn-222 will be uniformly distributed in the standard and sample bottles
without mixing before taking aliquots of the water for analysis. In an experi-
ment to check the Rn-222 distribution without mixing, three 1u ml aliquots from
each of 5 samples were taken and counted by liquid scintillation. The precision
was 1.7 percent at 9S percent confidence.
When water samples are shipped to the laboratory as water-only samples (not as
water/liquid scintillator mixtures), a detergent type liquid scintillator can
be used. If the analyst is concerned about Ra-226 also present in the sample,
37
-------
a second count about one week from the first count will indicate the signifi-
cance of the Ra-226 fraction. A detergent liquid scintillator will give about
28% higher counting efficiency than the oil based liquid scintillator. You
will note on the data sheets provided that both types of liquid scintillators
are indicated. Please indicate which solution you used in the "Method Used"
column.
Aeration and negative pressure should be minimized when transferring aliquots
of the standard and sample water. All of the aliquots to be analyzed should be
transferred to liquid scintillation vials or gas bubblers (for Lucas cell
analysis) within a short time (within one hour) after opening the bottle to
avoid 10ss of Rn-222 to the air layer above the water. Aliquots should be
transferred to preweighed liquid scintillation vials containing 10 ml of liquid
scintillator. or to preweighed gas bubblers. so that aliquot weights can be
determined.
The following calculations can be used for both methods.
Using the standard provided. the Rn-222 cpm/pCi factor (F) is determined.
A
g- x D x E
Rn-222 cpm/pCi.
F =
C x G x H
then. using the factor F, the sample Rn-222 pCi/1000 g or p Ci/l is determined.
A
g- x D x E x
1000 g
A
Sample Rn-222 p Ci/1000 9 (or pCi/l)
=
C x F x 1 (1000 g)
where:
A = Total standard or sample weight (g)
B = Standard or sample aliquot weight (g)
C = Rn-2~2 ingrowth factor. see attached table (see Note 1)
D = Aliquot net cpm at the midpoint of the count
E = Decay factor (decay time from the end of ingrowth to
the midpoint of the count) see attached table)
F = Rn-222 cpm/pCi (see note 2)
G = Ra-226 pCi in the standard source package
H = Rn-222 transfer factor (the fraction of the ingrown
Rn-222 in the standard source package that transferred
to the water).
Note 1:
An ingrowth factor is needed for the standard and samples provided
because they are supplied with Rn-222 generating sources. An ingrowth
factor will not be used for environmental samples. Only a decay
factor will be needed for environmental samples.
38
-------
Note 2:
This factor can be used for the standard provided or other Ra-226/
Rn-222 source packages prepared as described herein and contained in
water in a glass bottle capped with a 20 mm Poly Seal cap. This
factor can also be applied in the calculation for Rn-222 concentra-
tions in environmental water samples that are collected in glass
bottles, filled completely and capped with 20 mm Poly Seal caps.
If you have any questions about these instructions or the standards and samples
provided, please contact Earl Whittaker at (702) 798-2134 (FTS 545-2134).
Please send your test results to the following address by January 15, 1987.
Thank you for your interest and participation in this study.
Sincerely,
Earl Whittaker
Lockheed Engineering and
Management Services Co., Inc.
Environmental Programs Office
105U E. Flamingo Road, Suite 120
Las Vegas, NV 89119
EW:meo
cc:
J.O. 70.12
WP-0802C
39
-------
DATA REPORT SHEET - STANDARD Ra-226/Rn-222
Std No.
Ra-226 Source Activity
Total Standard Water Weight
Methods of measuring the Water for Rn-222
g
l.
2.
Lucas Cell (LC)
Liquid Scintillation (LS)
a. Oil based scintillator
b. Detergent scintillator
solution (LS-O)
solution (LS-D)
Aliquot
wt. g
Rn-222
Ingrowth
(days)
Ttl Std.
Water
cpm
Factor
Method cpm/
Used pCi
Ingrown Aliquot
Ingrowth Rn-222 . Net cpm
Factor pCi (decay 6t=0)
l.
2.
3.
4.
5.
6.
40
pCi
-------
DATA REPORT SHEET - SAMPLE A
Sample A
. Total Sample Water Weight
Methods of measuring the Water Sample for Rn-222
1. Lucas Cell (LC)
2. Liquid Scintillation (LS)
a. Oil based scintillator
b. Detergent scintillator
solution (LS-O)
solution (LS-D)
Aliquot
Grams (g)
Rn-222 Aliquot
Ingrowth (decay 6t=0) Method
days Net CPM Used
Tota 1 Tota 1
Sample Sample
CPM Rn-222 pCI
RN-222
pCi/1000g
1.
2.
3.
4.
5.
6.
41
g
-------
DATA REPORT SHEET - SAMPLE B
Sample B
, Total Sample Water Weight
Methods of measuring the Water Sample for Rn-222
1. Lucas Cell (LC)
2. Liquid Scintillation (LS)
a. Oil based scintillator solution
b. Detergent scintillator solution
Aliquot
Grams (g)
Rn-222 Aliquot
Ingrowth (decay ~t=O) Method
days Net CPM Used
1.
2.
3.
4.
5.
6.
(LS-O)
(L S-D )
Total Total
Sample Sample
CPM Rn-222 pCi.
42
RN-222
pCi /l OOOg
9
-------
DATA REPORT SHEET - SAMPLE C
Sample C
. Total Sample Water Weight
Methods of measuring the Water Sample for Rn-222
1. Lucas Cell (LC)
2. Liquid Scintillation (LS)
a. Oil based scintillator
b. Detergent scintillator
solution (LS-O)
solution (LS-D)
Aliquot
Grams (g)
Rn-222 Aliquot
Ingrowth (decay 6t=O) Method
days Net CPM Used
Total Total
Sample Sample
CPM Rn-222 pCi
RN-222
pCi/lOOOg
1.
2.
3.
4.
5.
6.
43
g
-------
6t (days)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
25
30
RADON-222 INGROWTH
Factor (l-e-At)
0.16590
0.30428
0.41970
0.51597
0.59627
0.66325
0.71911
0.76571
0.80458
0.83700
0.86404
0.88660
0.90541
0.92110
0.93419
0.94511
0.95422
0.96181
0.96815
U.97343
0.97784
0.98927
0.99567
44
-------
l1t (Hrs)
1
2
3
4
5
6
7
8
9
. 10
11
12
13
14
15
16
17
18
19
.20
21
22
23
24
Factor (Ao = At eAt)
1. 00758
1. 01523
1.02293
1.03069
1. 03851
1.04639
1.05433
1.06233
1.07039
1.07851
1.08669
1.09494
1.10325
1.11162
1.12005
1.12855
1.13711
1.14574
1.15443
1.16319
1.17201
1.18091
1. 18986
1.19889
RADON-222 DECAY
l1t (days)
1
2
2
4
5
6
7
8
9
10
45
Factor (Ao = At eAt)
1. 19889
1. 43735
1. 72323
2.06597
2.47688
2.96952
3.56014
4.26823
5.11716
6.13494
------- |