ASTM E385-90(1996)
(Test Method)Standard Test Method for Oxygen Content Using a 14-MeV Neutron Activation and Direct-Counting Technique
Standard Test Method for Oxygen Content Using a 14-MeV Neutron Activation and Direct-Counting Technique
SCOPE
1.1 This test method covers the measurement of oxygen concentration in almost any matrix by using a 14-MeV neutron activation and direct-counting technique. Essentially, the same system may be used to determine oxygen concentrations ranging from over 50% to about 10 [mu]g/g, or less, depending on the sample size and available 14-MeV neutron fluence rates. Note 1-The range of analysis may be extended by using higher neutron fluence rates, larger samples, and higher counting efficiency detectors.
1.2 This test method may be used on either solid or liquid samples, provided that they can be made to conform in size, shape, and macroscopic density during irradiation and counting to a standard sample of known oxygen content. Several variants of this method have been described in the technical literature. A monograph is available which provides a comprehensive description of the principles of activation analysis using a neutron generator (1).
1.3 The values stated in either SI or inch-pound units are to be regarded separately as the standard. The values given in parentheses are for information only.
1.4 This standard does not purport to address all of the safety problems 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. Specific precautions are given in Section 8.
General Information
Relations
Standards Content (Sample)
Designation: E 385 – 90 (Reapproved 1996)
Standard Test Method for
Oxygen Content Using a 14-MeV Neutron Activation and
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Direct-Counting Technique
This standard is issued under the fixed designation E 385; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (e) indicates an editorial change since the last revision or reapproval.
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1. Scope by Radioactivation Techniques
2.2 U.S. Government Document:
1.1 This test method covers the measurement of oxygen
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Code of Federal Regulations, Title 10, Part 20
concentration in almost any matrix by using a 14-MeV neutron
activation and direct-counting technique. Essentially, the same
3. Terminology
system may be used to determine oxygen concentrations
3.1 Definitions (see also Terminology E 170):
ranging from over 50 % to about 10 μg/g, or less, depending on
3.1.1 accelerator, n—a machine that ionizes a gas and
the sample size and available 14-MeV neutron fluence rates.
electrically accelerates the ions onto a target. The accelerator
NOTE 1—The range of analysis may be extended by using higher
may be based on the Cockroft-Walton, Van de Graaff, or other
neutron fluence rates, larger samples, and higher counting efficiency
design types (1). Compact sealed-tube, mixed deuterium and
detectors.
tritium gas, Cockcroft-Walton neutron generators are most
1.2 This test method may be used on either solid or liquid
commonly used for 14-MeV neutron activation analysis. How-
samples, provided that they can be made to conform in size,
ever, “pumped” drift-tube accelerators that use replaceable
shape, and macroscopic density during irradiation and counting
tritium-containing targets are also still in use. A review of
to a standard sample of known oxygen content. Several
operational characteristics, descriptions of accessory instru-
variants of this method have been described in the technical
mentation, and applications of accelerators used as fast neutron
literature. A monograph is available which provides a compre-
generators is given in Ref (2).
hensive description of the principles of activation analysis
3.1.2 comparator standard, n—a reference standard of
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using a neutron generator (1).
known oxygen content whose specific counting rate (counts
−1 −1
1.3 The values stated in either SI or inch-pound units are to
min [mg of oxygen] ) may be used to quantify the oxygen
be regarded separately as the standard. The values given in
content of a sample irradiated and counted under the same
parentheses are for information only.
conditions. Often, a comparator standard is selected to have a
1.4 This standard does not purport to address all of the
matrix composition, physical size, density and shape very
safety concerns, if any, associated with its use. It is the
similar to the corresponding parameters of the sample to be
responsibility of the user of this standard to establish appro-
analyzed. Comparative standards prepared in this way may be
priate safety and health practices and determine the applica-
used directly as “monitors” (see 3.1.4) in order to avoid the
bility of regulatory limitations prior to use. Specific precau-
need for monitor-sample calibration plots, in those cases where
tions are given in Section 8.
the usual monitor reference standard is physically or chemi-
cally dissimilar to the samples to be analyzed.
2. Referenced Documents
3.1.3 14-MeV neutron fluence rate, n—the areal density of
2.1 ASTM Standards:
neutrons passing through a sample, measured in terms of
−2 −1
E 170 Terminology Relating to Radiation Measurements
neutrons cm s , that is produced by the fusion reaction of
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and Dosimetry
deuterium and tritium ions accelerated to energies of typically
E 181 Test Methods for Detector Calibration and Analysis
150 to 200 keV in a small accelerator. Fluence rate is also
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of Radionuclides
commonly referred to as “flux density.” The total neutron
E 496 Test Method for Measuring Neutron Fluence Rate
fluence is the fluence rate integrated over time.
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3 4
and Average Energy from H(d,n) He Neutron Generators
3.1.3.1 Discussion—The H(d,n) He reaction is used to pro-
duce approximately 14.7-MeV neutrons. This reaction has a
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Q-value of + 17.586 MeV.
This test method is under the jurisdiction of ASTM Committee E-10 on Nuclear
Technology and Applicationsand is the direct responsibility of Subcommittee 3.1.4 monitor, n—any type of detector or comparison ref-
E10.05on Nuclear Radiation Metrology.
erence material that can be used to produce a response
Current edition approved Oct. 26, 1990. Published August 1991. Originally
published as E 385 – 69 T. Last previous edition E 385 – 80.
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The boldface numbers in parentheses refer to a list of references at the end of
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the text. Available from the Superintendent of Documents, U.S. Government Printing
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Annual Book of ASTM Standards, Vol 12.02. Office, Washington,
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