ASTM D1890-96
(Test Method)Standard Test Method for Beta Particle Radioactivity of Water
Standard Test Method for Beta Particle Radioactivity of Water
SCOPE
1.1 This test method covers the measurement of beta particle activity of water, as referenced to the beta energy of 137 Cs, not corrected for conversion electrons. It is applicable to beta emitters having maximum energies above 0.1 MeV and at activity levels above 0.02 Bq/mL of radioactive homogeneous water for most counting systems. This test method is not applicable to samples containing radionuclides that are volatile under conditions of the analysis.
1.2 This test method can be used for either absolute or relative determinations. In tracer work, the results may be expressed by comparison with a standard which is defined to be 100%. For radioassay, data may be expressed in terms of a known radionuclide standard if the radionuclides of concern are known and no fractionation occurred during processing, or may be expressed arbitrarily in terms of some other standard such as cesium-137. General information on radioactivity and measurement of radiation may be found in the literature and Practice D3648.
1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
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An American National Standard
Designation:D 1890–96
Standard Test Method for
Beta Particle Radioactivity of Water
This standard is issued under the fixed designation D 1890; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (e) indicates an editorial change since the last revision or reapproval.
This standard has been approved for use by agencies of the Department of Defense.
1. Scope Applicable Methods of Committee D-19 on Water
D3370 Practices for Sampling Water from Closed Con-
1.1 This test method covers the measurement of beta par-
duits
ticleactivityofwater,asreferencedtothebetaenergyof Cs,
D3648 Practice for the Measurement of Radioactivity
not corrected for conversion electrons. It is applicable to beta
emitters having maximum energies above 0.1 MeV and at
3. Terminology
activity levels above 0.02 Bq/mL of radioactive homogeneous
3.1 Definitions of Terms Specific to This Standard:
water for most counting systems. This test method is not
3.1.1 Becquerel—a unit of radioactivity equivalent to 1
applicabletosamplescontainingradionuclidesthatarevolatile
nuclear transformation per second.
under conditions of the analysis.
3.1.2 beta energy, maximum—the maximum energy of the
1.2 This test method can be used for either absolute or
beta-particle energy spectrum produced during beta decay of a
relative determinations. In tracer work, the results may be
given radioactive species.
expressedbycomparisonwithastandardwhichisdefinedtobe
100%. For radioassay, data may be expressed in terms of a
NOTE 1—Since a given beta-particle emitter may decay to several
known radionuclide standard if the radionuclides of concern different quantum states of the product nucleus, more than one maximum
energy may be listed for a given radioactive species.
are known and no fractionation occurred during processing, or
may be expressed arbitrarily in terms of some other standard
3.1.3 counter background—in the measurement of radioac-
such as cesium-137. General information on radioactivity and
tivity, the counting rate resulting from factors other than the
measurement of radiation may be found in the literature and
radioactivity of the sample and reagents used.
Practice D3648.
NOTE 2—Counter background varies with the location, shielding of the
1.3 This standard does not purport to address all of the
detector, and the electronics; it includes cosmic rays, contaminating
safety concerns, if any, associated with its use. It is the
radioactivity and electrical noise.
responsibility of the user of this standard to establish appro-
3.1.4 counter beta-particle effıciency—in the measurement
priate safety and health practices and determine the applica-
of radioactivity, that fraction of beta particles emitted by a
bility of regulatory limitations prior to use.
source which is detected by the counter.
2. Referenced Documents 3.1.5 counter effıciency—in the measurement of radioactiv-
ity, that fraction of the disintegrations occurring in a source
2.1 ASTM Standards:
3 which is detected by the counter.
D1129 Terminology Relating to Water
3 3.1.6 radioactive homogeneous water—water in which the
D1193 Specification for Reagent Water
radioactive material is uniformly dispersed throughout the
D2777 Practice for Determination of Precision and Bias of
volume of water sample and remains so until the measurement
is completed or until the sample is evaporated or precipitating
reagents are added to the sample.
This test method is under the jurisdiction ofASTM Committee D-19 on Water
3.1.7 reagent background—in the measurement of radioac-
andisthedirectresponsibilityofSubcommitteeD19.04onMethodsofRadiochemi-
tivity of water samples, the counting rate observed when a
cal Analysis.
Current edition approved Feb. 10, 1996. Published April 1996. Originally
sample is replaced by mock sample salts or by reagent
published as D1890–61T. Last previous edition D1890–90.
chemicals used for chemical separations that contain no
Friedlander, G., et al., Nuclear and Radiochemistry, 3rd Ed., John Wiley and
analyte.
Sons, Inc., New York, NY, 1981.
Price,W.J.,NuclearRadiationDetection,2ndEd.,McGraw-HillBookCo.,Inc.,
NOTE 3—Reagent background varies with the reagent chemicals and
New York, NY, 1964.
analytical methods used and may vary with reagents from different
Lapp, R. E., and Andrews, H. L., Nuclear Radiation Physics, 4th Ed.,
Prentice-Hall Inc., New York, NY, 1972.
Overman,R.T.,andClark,H.M., Radioisotope Techniques,McGraw-HillBook
Co., Inc., New York, NY, 1960.
3 4
Annual Book of ASTM Standards, Vol 11.01. Annual Book of ASTM Standards, Vol 11.02.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
D 1890–96
manufacturers and from different processing lots.
G = point source geometry (defined by the solid angle
p
3.2 Definitions—Fortermsnotdefinedinthistestmethodor subtended by the sensitive area of the detector),
f = backscatterfactororratioof cpswithbackingto cps
in Terminology D1129, reference may be made to other
bs
without backing,
published glossaries.
f = factor to correct for losses due to absorption in the
aw
4. Summary of Test Method
air and window of external detectors. It is equal to
the ratio of the actual counting rate to that which
4.1 Beta radioactivity may be measured by one of several
wouldbeobtainediftherewerenoabsorptionbythe
types of instruments composed of a detecting device and
air and window between the source and sensitive
combined amplifier, power supply, and scaler—the most
volume of the detector. Expressed in terms of
widely used being proportional or Geiger-Müller counters.
absorption coefficient and density of absorber,
Where a wide range of counting rates is encountered (0.1 to
−µx
f = e , where µ = absorption coefficient, in
1300 counts per seconds), the proportional-type counter is aw
square centimetres per milligram, and x=absorber
preferable due to a shorter resolving time and greater stability
density in milligrams per square centimetre.
of the instrument. The test sample is reduced to the minimum
f = factor to correct a spread source counting rate to the
weight of solid material having measurable beta activity by d
counting rate of the same activity as a point source
precipitation, ion exchange resin, or evaporation techniques.
on the same axis of the system,
Beta particles entering the sensitive region of the detector
f = factortocorrectfortheabsorptionandscatterofbeta
produceionizationofthecountinggas.Thenegativeionofthe ssa
particles within the material accompanying the ra-
original ion pair is accelerated towards the anode, producing
dioactive element, and
additional ionization of the counting gas and developing a
f = factor for coincident events to correct the counting
c
voltage pulse at the anode. By use of suitable electronic
rate for instrument resolving time losses and defined
apparatus, the pulse is amplified to a voltage sufficient for
by the simplified equation, f =1− nr, where,
c
operation of the counter scaler. The number of pulses per unit
n = the observed counts per second, and
of time is related to the disintegration rate of the test sample.
r=instrument resolving time in seconds. Generally,
Thebeta-particleefficiencyofthesystemcanbedeterminedby
the sample size or source to detector distance is
use of prepared standards having the same radionuclide com-
varied to obtain a counting rate that precludes
position as the test specimen and equivalent residual plated
coincident losses. Information on the effect of ran-
solids.An arbitrary efficiency factor can be defined in terms of
domdisintegrationandinstrumentresolvingtimeon
some other standard such as cesium-137.
the sample count rate as well as methods for
5. Significance and Use determining the resolving time of the counting
system may be found in the literature.
5.1 This test method was developed for the purpose of
For most applications, a detector system is calibrated using a
measuring the gross beta radioactivity in water. It is used for
singlebetaemittingradionuclideandanefficiencyofdetection,
the analysis of both process and environmental water to
f , response curve generated for various sample residue
determine gross beta activity. o
weights. The efficiency of detection for each sample residual
6. Measurement Variables weight incorporates all the factors mentioned above so that:
6.1 The relatively high absorption of beta particles in the
f 5 cps/Bq 5 ~G !~f !~f !~f !~f !~f ! (2)
o p bs aw d ssa c
sample media and any material interposed between source and
6.1.1 In tracer studies or tests requiring only relative mea-
sensitive volume of the counter results in an interplay of many
surements in which the data are expressed as being equivalent
variables which affect the counting rate of the measurement.
to a defined standard, the above correction factors can be
Thus, for reliable relative measurements, hold all variables
simply combined into a counting efficiency factor. The use of
constant while counting all test samples and standards. For
a counting efficiency factor requires that sample mounting,
absolute measurements, appropriate correction factors are ap-
density of mounting dish, weight of residue in milligrams per
plied. The effects of geometry, backscatter radiation, source
squarecentimetre,andradionuclidecomposition,inadditionto
diameter, self-scatter and self-absorption, absorption in air and
conditions affecting the above described factors, remain con-
detector window for external counters, and counting coinci-
stant throughout the duration of the test and that the compara-
dence losses have been discussed and may be described by
tive standard be prepared for counting in the same manner as
the following relation:
the test samples. The data from comparative studies between
cps 5 Bq ~G !~f !~f !~f !~f !~f ! (1)
b p bs aw d ssa c
independentlaboratories,whennotexpressedinabsoluteunits,
are more meaningful when expressed as percentage relation-
where:
shipsorastheequivalentofadefinedstandard.Expressingthe
cps = recorded counts per second corrected for back-
data in either of these two ways minimizes the differences in
ground,
counters and other equipment and in techniques used by the
Bq = disintegrations per second yielding beta particles,
b
laboratories conducting the tests.
6.2 The limit of sensitivity for both Geiger-Muller and
proportional counters is a function of the background counting
American National Standard Glossary of Terms in Nuclear Science and
Technology (ANSI N1.1). rate. Massive shielding or anti-coincidence detectors and
D 1890–96
circuitry, or both, are generally used to reduce the background useofadetectorwithoutashieldwillsignificantlyincreasethe
counting rate to increase the sensitivity. background and the detection capability.
8.1.3 Scaler—Normally the scaler, mechanical register,
7. Interferences
power supply, and amplifier are contained in a single chassis,
7.1 Material interposed between the test sample and the
generally termed the scaler. The power supply and amplifier
instrumentdetector,aswellasincreasingdensityinthesample
sections are matched by the manufacturer with the type of
containing the beta emitter, produces significant losses in
detectortoproducesatisfactoryoperatingcharacteristicsandto
sample counting rates. Liquid samples are evaporated to
provide sufficient range in adjustments to maintain controlled
dryness in dishes that allow the sample to be counted directly
conditions. The manufacturer shall provide resolving time
by the detector. Since the absorption of beta particles in the
information for the counting system. The scaler shall have
sample solids increases with increasing density and varies
capacity for storing and visually displaying at least 10 counts
inversely with the maximum beta energy, plated solids shall
and with a resolving time no greater than 250µ s for use with
remain constant between related test samples and should
Geiger Muller detectors or 5 µs for use with proportional
duplicate the density of the solids of the plated standard.
detectors. The instrument shall have an adjustable input sensi-
7.2 Most beta radiation counters are sensitive to alpha,
tivity matched and set by the manufacturer to that of the
gamma, and X-ray radiations, with the degree of efficiency
dependent upon the type of detector. The effect of interfering detector, and a variable high-voltage power supply with indi-
radiations on the beta counting rate is more easily evaluated cating meter.
withexternal-typecounterswhereappropriateabsorberscanbe
8.2 Sample Mounting—Sample mounting shall utilize
used to evaluate the effects of interfering radiation.
dishes having a flat bottom of a diameter no greater than that
of the detector window preferably having 3.2-mm high side
8. Apparatus
walls with the angle between dish bottom and side equal to or
8.1 Beta Particle Counter, consisting of the following
greater than 120° to reduce side-wall scattering (Note 4).
components:
Dishes shall be of a material that will not corrode under the
8.1.1 Detector—The end-window Geiger-Muller tube and
plating conditions and should be of uniform surface density
the internal or external sample gas-flow proportional chambers
preferably great enough to reach backscatter saturation.
are the two most prevalent commercially available detector
types. The material used in the construction of the detector
NOTE 4—Sample dishes with vertical side walls may be used but the
should be free from detectable radioactivity. When detectors
exactpositioningofthesedishesrelativetothedetectorisveryimportant.
contain windows, the manufacturer shall supply the window
This factor becomes critical for dishes having the same diameter as the
density expressed in milligrams per square centimetre. To
detector. Dishes having side walls more than 3.2 mm in height are not
establish freedom from undesirable characteristics, the manu-
recommended. Stainless steel has been found to be satisfactory for this
facturer shall supply voltage plateau and background counting purpose.
ratedata.Voltageplateaudatashallshowthethresholdvoltage,
8.3 Alpha Particle Absorber—Aluminum or plastic, having
slope, and length of plateau. Detectors requiring external
a uniform density such that total absorbing medium (air plus
positioningofthetestsamplearemountedonatubesupportof
window plus absorber) between sample and sensitive volume
low-density material (aluminum or plastic) and positioned so
of detector is approximately equal to 7 mg/cm of aluminum.
thecenterofthewindowisdirectlyabovethece
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