EPA-680/4 75-005
JUNE 1975
Environmental Monitoring Series
TENTATIVE REFERENCE METHOD FOR THE
MEASUREMENT OF GROSS ALPHA AND
GROSS BETA RADIOACTIVITIES
IN ENVIRONMENTAL WATERS
NATIONAL ENVIRONMENTAL RESEARCH CENTER
OFFICE OF RESEARCH AND DEVELOPMENT
US ENVIRONMENTAL PROTECTION AGENCY
LAS VEGAS, NEVADA 89114
-------
RESEARCH REPORTING SERIES
Research reports of the Office of Research and Develop-
ment, U. S. Environmental Protection Agency, have been
grouped into five series. These five broad categories
were established to facilitate further development and
application of environmental technology. Elimination of
traditional grouping was consciously planned to foster
technology transfer and a maximum interface in related
fields. The five series are:
1. Environmental Health Effects Research
2. Environmental Protection Technology
3. Ecological Research
4. Environmental Monitoring
5. Socioeconomic Environmental Studies
This report has been assigned to the ENVIRONMENTAL MONI-
TORING series. This series describes research conducted
to develop new or improved methods and instrumentation
for the identification and quantification of environ-
mental pollutants at the lowest conceivable significant
concentrations. It also includes studies to determine
the ambient concentrations of pollutants in the environ-
ment and/or the variance of pollutants as a function of
time or meteorological factors.
EPA REVIEW NOTICE
This report has been reviewed by the National Environ-
mental Research Center-Las Vegas, EPA, and approved for
publication. Approval does not signify that the contents
necessarily reflect the views and policies of the U.S.
Environmental Protection Agency, nor does mention of
trade names or commercial products constitute endorse-
ment or recommendation of use.
Document is available to the public for sale through
the National Technical Information Service, Springfield,
Virginia 22161.
-------
EPA-680/4-75-005
June 1975
TENTATIVE REFERENCE METHOD FOR THE MEASUREMENT OF GROSS ALPHA
AND GROSS BETA RADIOACTIVITIES IN ENVIRONMENTAL WATERS
by
Quality Assurance Branch
Technical Support Laboratory
National Environmental Research Center
Las Vegas, Nevada
ROAP Nunter 22ACW
Program Element 1HA327
NATIONAL ENVIRONMENTAL RESEARCH CENTER
OFFICE OF RESEARCH AND DEVELOPMENT
U.S. ENVIRONMENTAL PROTECTION AGENCY
LAS VEGAS, NEVADA 89114
-------
CONTENTS
Page
1. Principle and Applicability 1
2. Range and Sensitivity 2
3. Interferences 3
4. Precision and Accuracy 4
5. Apparatus 6
6. Reagents 8
7. Procedure 8
8. Calibration 12
9. Calculations and Reporting 12
References 15
Bibliography 15
APPENDIX. Error and Statistical Calculations 16
iii
-------
TENTATIVE REFERENCE METHOD FOR THE MEASUREMENT OF GROSS ALPHA
AND GROSS BETA RADIOACTIVITIES IN ENVIRONMENTAL WATERS
1. Principle and Applicability
Measurable amounts of alpha and beta emitting radionuclides are
found in most environmental waters. These may be naturally occurring
radionuclides such as uranium, radium, thorium, and potassium-40, or
they may be the result of man-made (artificial) radionuclides. These
naturally occurring elements (radium and thorium), through their
daughter gases, cause an appreciable airborne particulate activity
which may contribute to the radioactivity of environmental waters
through fallout (carried by rain or snow). Artificial radionuclides
may be released to the environment through fallout or by contamination
of process and waste water (resulting) from nuclear reactors, weapons
testing, medical waste, and nuclear reprocessing plants.
Just as there are differences in the toxicities of the various
stable elements, there are differences in the radiotoxicities of the
various radionuclides. Radium-226 and strontium-90 are two radio-
isotopes, found in potable water, with very high radiotoxicities.
The 1962 Public Health Service Drinking Water Standards recommended
limits of 3 pCi/liter for radium-226 and 10 pCi/liter for strontium-90.
In these standards an upper limit of 1000 pCi/liter of gross beta
activity (in the absence* of alpha emitters and strontium-90) was set.
However, the drinking water guidelines currently under consideration
by the EPA set limits for radium-226 and radium-228 at 5 pCi/liter and
* Absence is intended to mean a negligible small fraction of the limits
established for these radionuclides and the limit for unidentified alpha
emitters is taken as the listed limit for radium-226.
-------
gross alpha activity (including radium-226) at 15 pCi/liter. Gross
beta limit is set at 50 pCi/liter corrected for potassium-40 and other
naturally occurring radionuclides.
Methods for the analysis of radium-226 and strontium-90 are com-
plex and time consuming. There are large numbers of water sources that
must be checked routinely for radioactivity. Therefore, the measure-
ment of gross alpha and gross beta radioactivities provides a rapid
screening method which will indicate or negate the need for specific
analysis of the more hazardous radionuclides (radium-226 and
strontium-90).
This method describes the measurement of gross alpha and gross
beta radioactivities and provides for the analysis of radionuclides
in both the soluble and insoluble fractions of environmental water
samples. Radionuclides that are volatile under the sample preparation
conditions required by this method will not be measured.
2. Range and Sensitivity
The method is applicable to the measurement of alpha emitters
having energies above 3.9 megaelectronvolts (MeV) and beta emitters
having maximum energies above 0.1 MeV.
The minimum limit of concentration to which this method is appli-
cable will depend on sample size, counting system characteristics,
background, and counting time.
The decay of radioactivity is random in nature rather than uniform.
Therefore, the emissions of radioactive decay (alpha and beta particles,
and gamma photons) must be counted sufficiently long to obtain the
desired statistical reliability. It is recommended that samples be
counted long enough so that samples with activities as low as the de-
tection limit of the method and counting instrument used will have a
counting error of plus or minus (±) counts per minute (cpm) at the
95 percent confidence level of no more than the sample net count rate
-------
(when counting error cpm equals net cpm, the counting error is 100 per-
cent). For instance, when a 1-liter water sample aliquot containing
200 milligrams (mg) of sample residue solids is evaporated in a 2-inch
diameter counting dish and counted for 20 minutes for gross beta
activity in an external proportional counting system having a back-
ground of 2 cpm, with a counting efficiency of 30 percent, and the
gross count rate is 3 cpm, the sample will have a net count rate of
1 cpm and a counting error of ± 1 cpm at the 95 percent confidence
level. This corresponds to a detection limit of 1.5 ± 1.5 pCi/liter.
Also, when a 1-liter water sample aliquot containing 87 mg of sample
residue solids is evaporated in a 2-inch diameter counting dish and
counted for 50 minutes for gross alpha activity in an alpha scintilla-
tion system having a background of 0.005 cpm, with a counting efficiency
of 30 percent, and the gross count rate is 0.09 cpm, the sample will
have a net count rate of 0.085 cpm and a counting error of ± 0.085 cpm
at the 95 percent confidence level. This corresponds to a detection
limit of 0.13 ± 0.13 pCi/liter. Counting efficiency will increase
with less sample residue resulting in a correspondingly lower detection
limit. Samples having activities above the detection limits and counted
for the times indicated above (20 minutes for gross beta and 50 minutes
for gross alpha) will have correspondingly lower counting error. See
the Appendix.
3. Interferences
Since the radionuclides are not separated from the evaporated
sample residue, the sample residue serves as an' interference, absorbing
alpha and beta particles emitted from the radionuclides. Moisture
adsorbed or trapped by the sample residue also is an interference for
the reason stated above. If a sample is counted in an internal propor-
tional counter, static charge on the sample residue can cause erratic
counting, thereby preventing an accurate count.
-------
Non-uniformity of the sample residue in the counting dish inter-
feres with the precision of the method.
4. Precision and Accuracy
4.1 Gross alpha and gross beta measurement by this method has a built-
in inaccuracy in that samples may contain alpha and beta emitters
with energies different from the standards used. In such circumstances
the counting efficiencies used will not give accurate information
(counts per minute to disintegrations per minute) for the radionuclides
in the sample. However, the method at best is good only for screening
or checking trends. The importance of precision (or repeatability)
is that a given water source will be checked periodically for gross
alpha and beta and any significant changes in the results from one
time to the next may require specific analysis for radium-226,
strontium-90, or other suspected radionuclides. It is necessary then
that such changes be real and not a result of poor precision.
Water samples containing no more than 200 mg of evaporated (dried)
residue per liter with gross beta activity as low as 50 pCi/liter can be
analyzed with a precision of less than ± 10 percent at the 95 percent
confidence level (200 mg of sample residue in a 2-inch diameter count-
ing dish, counted for 20 minutes in a thin-window external proportional
gas flow counting system, with a counting efficiency of 30 percent).
Water samples containing no more than 87 mg of evaporated (dried)
residue per liter with gross alpha activity of 5 pCi/liter can be ana-
lyzed with a precision of less than ± 10 percent at the 95 percent
confidence level and with gross alpha activity of 500 pCi/liter, a
precision of less than ± 6 percent at the 95 percent confidence level
(87 mg of sample residue in a 2-inch diameter counting dish, counted
for 50 minutes in a thin-window external proportional gas flow counting
system, with a counting efficiency of 6 percent).
Precision of the gross alpha analysis can be improved by counting
the samples in an alpha scintillation system (mounting a zinc sulfide
-------
film directly on the sample residue, held in close contact by an o-ring
in the counting dish-, and counting in a light-tight system with a
photomultiplier tube detector).
Analytical results of spiked water samples prepared to contain as
low as 50 pCi/liter of cesium-137 (for gross beta) and 5 pd'/liter of
americium-241 (for gross alpha), analyzed by this method, and counted
in an external thin-window proportional counting system, should show
accuracies with deviations from the known values of less than ± 10 per-
cent at the 95 percent confidence level.
4.2 Counting Instruments
4.2.1 Internal Proportional Counter
There are inherent problems with this type of counting system;
however, it has been widely used in the past. Some problems in this
type of system are poor repeatability in counting due to static charges
building up on the sample surface and detector contamination from loose
sample residue. Also, it does not lend itself to automatic changing of
samples. A thin film of Lucite is dried on the sample residue to hold
the residue in place. Then a conductive film is also dried on the
Lucite film to reduce the buildup of static charges (1). Both coatings
add solids to the sample, thus adding to the sample self-absorption of
the emitted alpha and beta particles. Conductive solutions presently
available do not seem to improve substantially the counting repeat-
ability.
4.2.2 External Proportional Counter, Thin Window
This type of counting system is much the same as the internal
proportional counting system except that a thin window separates the
sample from the counting chamber. The window then acts as an absorber;
however, the window can be made sufficiently thin to minimize absorp-
tion. There is also air space between the sample dish and the detector
-------
window which absorbs to some extent, especially alpha particles. How-
ever, this type of counting system does give good repeatability in
counting and is, therefore, a recommended type of counting instrument.
Instruments of this type are available that have low background counts
and automatic sample changing.
4.2.3 Scintillation Counter
The detector for this type of counting system consists of a
photomultiplier tube on which is mounted a zinc sulfide (silver acti-
vated) coated film for alpha detection or a thin (0.020-inch) plastic
phosphor disc for beta detection. For alpha counting, efficiency can
be increased by placing the zinc sulfide film on or very close to the
sample instead of on the phototube. The cost of the zinc sulfide film
is low enough to allow for a one-sample use (about 20 cents for a
1-15/16-inch diameter film which can be used with a 2-inch diameter
counting dish). The cost of plastic phosphor discs is too high to
allow for a one-sample use (about $13.50 per disc).
This type of counting system does not lend itself to automatic
sample counting as well as the external proportional type because the
photomultiplier tube must be protected from light whenever high voltage
is applied. The scintillation-type counting system does give good
counting repeatability, good counting efficiencies, and has low back-
ground. Therefore, this is a recommended type of counting system.
Such systems for both alpha and beta scintillation counting have been
described in the literature (2,3).
5. Apparatus
One-liter (or one-quart) tight-sealing polyethylene
sample bottles
Tags or labels for sample identification
Filter holder for 47-millimeter filters
-------
47-millimeter diameter 0.45 micrometer membrane
filters (cellulose triacetate type)
Two-liter filter flask with stopper adapter for
filter holder
Tygon tubing (3/8-inch ID x 5/8-inch OD)
Graduated cylinders, 100, 250, and 1000 milliliter
Suction pump
Four-ounce polyethylene bottles with Poly-Seal caps.
To be used for taking portions of 8N nitric acid into
the field for sample collection (15 milliliter of
8N nitric acid per liter of sample)
Stainless steel counting dishes (2-inch diameter
by 1/4-inch deep) and o-rings to fit tight inside
of dishes
Drying oven
Desiccator and desiccant
Alpha and beta counting systems, such as:
Internal proportional counter - windowless
External proportional counter - thin window
Scintillation counting system:
Phototube with zinc sulfide film detector
for alpha counting
Phototube with thin plastic scintillator
disc for beta counting
Beakers, 250 and 400 milliliter
Zinc sulfide film discs, 1-15/16-inch diameter
(available from William B. Johnson and Associates, Inc.,
Research Park, Montville, New Jersey 07045)
-------
Plastic scintillator disc, 2-inch diameter (available
from Nuclear Enterprises, 935 Terminal Way, San Carlos,
California 94070)
6. Reagents. All chemicals should be of "reagent-grade" or
equivalent whenever they are commercially available.*
Concentrated nitric acid (16N)
1+1 nitric acid-water solution (volume dilution) (8N)
1+30 nitric acid-water solution (volume dilution) (0.5N)
30 percent hydrogen peroxide
7. Procedure
7.1 Sampling
Sampling may be accomplished as described in "Environmental
Radioactivity Surveillance Guide," published by the U.S. Environmental
Protection Agency as report ORP/SID 72-2. It is recommended that
samples be preserved at the time of collection by the addition of 15 ml
of 1+1 nitric acid-water solution (8N) per liter of sample collected.
This will make the sample normality about 0.1N and should reduce loss
of sample radioactivity to the container walls. However, if the radio-
activity in the separate dissolved and suspended fractions of the
sample is to be measured, those fractions must be separated before a
preservative is added since a preservative may change the distribution
* "Reagent Chemicals, American Chemical Society Specifications,"
American Chemical Society (ACS), Washington, DC. For reagents not
listed by the ACS see "Reagent Chemicals and Standards" by Joseph
Rosin, D. Van Nostrund Company, Inc., New York, NY, or the "United
States Pharmacopeia" for purity tests.
8
-------
of the sample radioactivity. Rather than separating the dissolved and
suspended solids fractions in the field, samples can be brought to the
laboratory without perservative added. Separation is then done by
filtering out the suspended solids on a tared 0.45 micrometer membrane
filter. The filter is dried, weighed, and set aside for further analy-
sis. The preservative solution is then added to the filtrate which is
returned to the original sample container and held there overnight or
longer before analysis is begun.
7.2 Analysis
7.2.1 Sample Size and Counting Efficiency
Sample residue self-absorption must be considered for both
alpha and beta radioactivities when choosing the sample aliquot size.
Therefore, the analyst must know the mass "abundance of the dissolved
and the suspended solids fractions of each water sample to be analyzed.
Such a determination is made by taking a measured aliquot of the water
sample, filtering it through a weighed 0.45 micrometer pore size mem-
brane filter, evaporating the filtrate in a tared beaker, drying the
filter and filtrate residue, and reweighing both to get increase due
to the dissolved and suspended solids fractions of the water sample.
Once the residue fractions have been determined for a given water
source there is no need to repeat the determination unless the source
has noticeably changed.
For each counting instrument to be used the analyst should pre-
pare a graph of water sample residue versus counting efficiency using
known amounts of cesium-137 for beta radioactivity and americium-241
for alpha radioactivity, varying the sample residue from 0 to 5 mg per
square centimeter (sq cm) of counting dish area for alpha and 0 to 10
mg per sq cm for beta. See Calibration (Section 8).
-------
7.2.2 Gross Alpha and Gross Beta Measurement of the Combined
Solids (Dissolved and Suspended)
7.2.2.1 If gross alpha and gross beta counts are to be made from
separate water sample aliquots, use an aliquot size that will
result in no more total solids than 10 mg per sq cm of counting dish
area for beta and 5 mg of solids per sq cm for alpha. It follows then,
that if both alpha and beta measurements are to be made from the same
water sample aliquot that the aliquot-solids limitation should be 5 mg
per sq cm of counting dish area.
7.2.2.2 Before taking aliquots, shake the sample bottle to mix its
contents.
7.2.2.3 To count an aliquot of the water sample, either evaporate
to dryness in small increments directly in a tared counting
dish or transfer the aliquot to a Pyrex beaker, evaporate to a small
volume, quantitatively transfer the concentrate to a tared counting
dish with 0.5N nitric acid and then evaporate to dryness. Do not allow
the sample residue to go to dryness in the beaker. A uniform deposition
of the sample residue in the counting dish is necessary for obtaining
reliable comparative counting data. This can be achieved by carefully
evaporating the sample concentrate in the counting dish on a variable-
temperature hot plate at a sufficiently low temperature to prevent the
sample from boiling or spattering. Evaporate the sample concentrate
in small portions (not more than 5 milliliters (ml) at a time) to mini-
mize solids deposition on the dish walls.
7.2.2.4 Dry the sample residue in a drying oven at 105° C for at
least 2 hours, cool in a desiccator, weigh, and count. If
the counting of the sample is to be delayed, store the sample residue
in a desicca'tor until the counting is to be done. Sample residue should
be very dry when counting is done because vapors from moist residue
will attack the detector window and/or detector.
10
-------
7.2.2.5 Count for alpha and beta radioactivities at their respective
voltage plateaus. If the sample is to be recounted for decay
information, store it in a desiccator.
7.2.2.6 For water sources that are turbid, it is recommended that a
sample aliquot be wet-ashed to reduce the solids. Evaporate
a sample aliquot to near dryness and then treat the residue with one
or more portions of 20 ml of concentrated nitric acid plus 2 ml of
30 percent hydrogen peroxide, heating and evaporating to near dryness
with each treatment. Then continue with the sample according to steps
7.2.2.3 through 7.2.2.5.
7.2.3 Gross Alpha and Gross Beta Measurements of the
Separate Dissolved and Suspended Solids
7.2.3.1 These samples should be filtered or preservative should be
added to them before they are sent to the laboratory. The
dissolved and the suspended solids fractions are separated by filtering
the sample through a weighed 0.45 micrometer pore size membrane filter.
Return the dissolved solids fraction (filtrate) to the original con-
tainer, add 15 ml of 8N nitric acid per liter of sample, and wait over-
night or longer before continuing the analysis on the dissolved solids
fraction. Place the filter in a weighed counting dish and place a
weighed o-ring in the dish to hold the filter flat (o-ring should be
tight fitting in the dish). Dry the filter for 2 hours at 105° C,
cool to room temperature and reweigh. An aliquot of the dissolved
solids is treated as in Section 7.2.2. If the suspended fraction
weighs not more than 5 mg per sq cm of counting dish area, count as
is for gross alpha and gross beta, and normalize the count to the
aliquot size used for the dissolved solids fraction. If the suspended
fraction weighs more than 5 mg per sq cm of counting dish area, that
fraction plus the filter should be wet ashed by the following step.
11
-------
7.2.3.2 Wet ashing of suspended solids can be accomplished by one
or more treatments with 20 ml of concentrated nitric acid
and 2 ml of 30% hydrogen peroxide in a 250-ml beaker, heating and
evaporating to near dryness with each treatment. Transfer the wet-
ashed residue with 0.5N nitric acid to a tared counting dish and con-
tinue with drying and counting as in Section 7.2.2. If the wet-ashed
residue is still more than 5 mg per sq cm of counting dish area, then
redissolve the residue, dilute to a known volume, and take an aliquot
equal to or less than 5 mg per sq cm of counting dish area and proceed
as in Section 7.2.2.
8. Calibration
Using standard solutions of cesium-137 (for beta radioactivity),
americium-241 (for alpha activity) and tap water, prepare reference
data for counting efficiency versus water solids per unit area of
counting surface. Add known amounts of alpha and beta radioactivity
to varying size aliquots of tap water. Evaporate the water aliquots,
transfer the solids concentrate to tared counting dishes, dry, and
count according to the procedure of Section 7.2.2. Correct the count-
ing data for background activity and plot counting efficiency versus
mg of solids per sq cm of counting dish area. Such a curve should be
determined for each counting instrument for both alpha and beta and
should cover the range of 0-10 mg per sq cm for beta and 0-5 mg per
sq cm for alpha. Counting efficiencies for calculating gross alpha
and gross beta radioactivities of environmental water sources are read
from these curves.
9. Calculations and Reporting
It is recommended that the gross alpha and gross beta radio-
activities be determined and reported in pCi/liter. When counting
beta radioactivity by gas flow proportional counting systems, alpha
radioactivity present in the sample (or sample fraction) is counted
12
-------
also unless the particular instrument being used is designed and has
been set for discriminating out the alpha pulses (higher energy).
Without instrumental discrimination it is necessary to subtract the
alpha activity (which had been counted at the alpha voltage plateau)
from the beta plus alpha activity (counted at the beta voltage plateau)
Determine alpha radioactivity by the following equation:
Alpha (pCi/liter) = net cPfflitx Cl
C26V
where net cpm = gross alpha counts minus the background
counts at the alpha voltage plateau
ci = 1000 ml/liter
c2 = 2.22 dpm/pCi
e = efficiency fraction, read from graph of
efficiency versus mg of water solids per
sq cm of counting dish area (alpha curve)
V•- volume of the aliquot analyzed, in ml
Determine beta radioactivity by the following equation:
Beta (pCi/liter) = net cpm..x Cl - alpha (pCi/liter)*
C26V
where GI = 1000 ml/liter
c2 = 2.22 dpm/pCi
e = efficiency fraction, read from graph of
efficiency versus mg of water solids per
sq cm of counting dish area (beta graph)
* The subtraction of alpha activity is necessary if the beta count is
performed without instrumental discrimination for alpha counts.
13
-------
net cpm = gross counts at the beta plateau voltage
minus the background counts at the beta
plateau voltage
Total water sample gross alpha and gross beta radioactivity is the
sum of dissolved solids and suspended solids radioactivities if sepa-
rated and analyzed separately.
Error associated with the results of the analysis should also
be reported. See the appendix for error and statistical calculations.
14
-------
REFERENCES
1. Standard Methods for the Examination of Water and Wastewater,
13th Edition, American Public Health Association, Washington, D.C.,
1971.
2. Harley, J. H., N. A. Hallden, and I. M. Fiscenna, "Beta Scintilla-
tion Counting with Thin Plastic Phosphors," Nucleonics, 20:59,
1961.
3. Hallden, N. A., and J. H. Harley, "An Improved Alpha-Counting
Technique," Analytical Chemistry, 32:1861, 1960.
BIBLIOGRAPHY
1974 Annual Book of ASTM Standards, Part 31, American Society for
Testing and Materials, Philadelphia, Pennsylvania.
Friedlander, G., 0. W. Kennedy, and J. Miller, Nuclear and Radio-
chemistry, John Wiley and Sons, Inc., New York, New York, 1964.
15
-------
APPENDIX. ERROR AND STATISTICAL CALCULATIONS
Because of the random nature of radioactivity disintegrations there
is an error associated with any measured count of these disintegrations.
The variability of any measurement is indicated by the standard devia-
tion. The standard deviation in the counting rate is determined by
the following equation:
« (R) •
B^
where RQ = gross count rate
ti = counting time for the gross count
B = background count rate
t2 = counting time for the background count
The counting error for a given sample expressed in pCi/liter and
at the 95% confidence level is shown by:
c _ Cia(R) x c2
where Ci = 1.96 = 95% confidence factor
c2 = 1000 ml /liter
C3 = 2.22 dpm/pCi
e = efficiency factor, cpm/dpm
V = volume of the aliquot analyzed, in ml
16
-------
The standard deviation associated with the overall random un-
certainty may be estimated by performing replicate analyses on a given
sample, and is calculated from the following equation:
n
m
- n)2/(m -
where n - activity (pCi/liter) of a given sample
n = mean activity (pCi/liter) of a series of analyses
m = the number of replicate analyses
17
-------
TECHNICAL REPORT DATA
(Please read Instructions on the reverse before completing)
REPORT NO.
EPA-680/4-75-005
3. RECIPIENT'S ACCESS!OI*NO.
4. TITLE AND SUBTITLE
Tentative Reference Method for the Measurement of
Gross Alpha and Gross Beta Radioactivities in
Environmental Waters
5. REPORT DATE
June 1975
6. PERFORMING ORGANIZATION CODE
7. AUTHOR(S)
Quality Assurance Branch
Technical Support Laboratory
8. PERFORMING ORGANIZATION REPORT NO.
PERFORMING ORG \NIZATION NAME AND ADDRESS
National Environmental Research Center
U.S. Environmental Protection Agency
P.O. Box 15027
Las Vegas, NV 89114
10. PROGRAM ELEMENT NO.
1HA327
11. CONTRACT/GRANT NO.
12. SPONSORING AGENCY NAME AND ADDRESS
Office of Research and Development
U.S. Environmental Protection Agency
Washington, DC 20460
13. TYPE OF REPORT AND PERIOD COVERED
14. SPONSORING AGENCY CODE
15. SUPPLEMENTARY NOTES
16. ABSTRACT
A tentative reference method for the measurement of gross alpha and gross beta
radioactivities in environmental waters is described. Samples of environmental
water sources are collected, preserved by acid treatment, and aliquots of the
samples are evaporated to dryness in a counting dish and counted for alpha and
beta activity. Counting efficiencies for sample aliquots are read from curves
prepared from counting data of prepared standards, using a known quantity of
cesium-137 and 0-10 milligrams of evaporated water dissolved solids per square
centimeter of counting dish area for gross beta, and a known quantity of
americium-241 and 0-5 milligrams of evaporated water dissolved solids per square
centimeter of counting dish area for gross alpha. Results are reported in
pCi/liter.
17.
KEY WORDS AND DOCUMENT ANALYSIS
DESCRIPTORS
b.lDENTIFIERS/OPEN ENDED TERMS
c. COSATI Field/Group
reference method
gross alpha
gross beta
environmental water
calibration
standards
Radiation Chemistry
Quality Assurance
Water Chemistry
Radioactivity
07 05
08 08
14 04
18 02.
20 08
04, 08
18. DISTRIBUTION STATEMENT
Release unlimited
19. SECURITY CLASS (ThisReport)
Unclassified
21. NO. OF PAGES
20
20. SECURITY CLASS (Thispage)
Unclassified
22. PRICE
EPA Form 2220-1 (9-73)
GPO 693-742/39
------- |