ASTM E262-17
(Test Method)Standard Test Method for Determining Thermal Neutron Reaction Rates and Thermal Neutron Fluence Rates by Radioactivation Techniques
Standard Test Method for Determining Thermal Neutron Reaction Rates and Thermal Neutron Fluence Rates by Radioactivation Techniques
SIGNIFICANCE AND USE
4.1 This test method can be extended to use any material that has the necessary nuclear and activation properties that suit the experimenter's particular situation. No attempt has been made to fully describe the myriad problems of counting techniques, neutron-fluence depression, and thick-foil self-shielding. It is assumed that the experimenter will refer to existing literature on these subjects. This test method does offer a referee technique (the standard gold foil) to aid the experimenter when they are in doubt of their ability to perform the radiometric technique with sufficient accuracy.
4.2 The standard comparison technique uses a set of foils that are as nearly identical as possible in shape and mass. The foils are fabricated from any material that activates by an (n, γ) reaction, preferably having a cross section approximately inversely proportional to neutron speed in the thermal energy range. Some of the foils are irradiated in a known neutron field (at NIST) or other standards laboratory). The foils are counted in a fixed geometry on a stable radiation-detecting instrument. The neutron-induced reaction rate of the foils is computed from the counting data, and the ratio of the known neutron fluence rate to the computed reaction rate is determined. For any given foil, neutron energy spectrum, and counting set-up, this ratio is a constant. Other foils from the identical set can now be exposed to an unknown neutron field. The magnitude of the fluence rate in the unknown field can be obtained by comparing the reaction rates as determined from the counting data from the unknown and reference field, with proper corrections to account for spectral differences between the two fields (see Section 5). One important feature of this technique is that it eliminates the need for knowing the detector efficiency.
4.3 This test method follows the Stoughton and Halperin convention for reporting thermal neutron fluence. Other conventions are the Wescott convention (fol...
SCOPE
1.1 The purpose of this test method is to define a general procedure for determining an unknown thermal-neutron fluence rate by neutron activation techniques. It is not practicable to describe completely a technique applicable to the large number of experimental situations that require the measurement of a thermal-neutron fluence rate. Therefore, this method is presented so that the user may adapt to their particular situation the fundamental procedures of the following techniques.
1.1.1 Radiometric counting technique using pure cobalt, pure gold, pure indium, cobalt-aluminum, alloy, gold-aluminum alloy, or indium-aluminum alloy.
1.1.2 Standard comparison technique using pure gold, or gold-aluminum alloy, and
1.1.3 Secondary standard comparison techniques using pure indium, indium-aluminum alloy, pure dysprosium, or dysprosium-aluminum alloy.
1.2 The techniques presented are limited to measurements at room temperatures. However, special problems when making thermal-neutron fluence rate measurements in high-temperature environments are discussed in 9.2. For those circumstances where the use of cadmium as a thermal shield is undesirable because of potential spectrum perturbations or of temperatures above the melting point of cadmium, the method described in Test Method E481 can be used in some cases. Alternatively, gadolinium filters may be used instead of cadmium. For high temperature applications in which aluminum alloys are unsuitable, other alloys such as cobalt-nickel or cobalt-vanadium have been used.
1.3 This test method may be used to determine the equivalent 2200 m/s fluence rate. The accurate determination of the actual thermal neutron fluence rate requires knowledge of the neutron temperature, and determination of the neutron temperature is not within the scope of the standard.
1.4 The techniques presented are suitable only for neutron fields having a significant thermal neutron component, in w...
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This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation: E262 − 17
Standard Test Method for
Determining Thermal Neutron Reaction Rates and Thermal
1
Neutron Fluence Rates by Radioactivation Techniques
This standard is issued under the fixed designation E262; 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 (´) indicates an editorial change since the last revision or reapproval.
1. Scope 1.4 The techniques presented are suitable only for neutron
fields having a significant thermal neutron component, in
1.1 The purpose of this test method is to define a general
which moderating materials are present, and for which the
procedure for determining an unknown thermal-neutron flu-
average scattering cross section is large compared to the
ence rate by neutron activation techniques. It is not practicable
average absorption cross section in the thermal neutron energy
to describe completely a technique applicable to the large
range.
number of experimental situations that require the measure-
ment of a thermal-neutron fluence rate. Therefore, this method 1.5 Table 1 indicates the useful neutron-fluence ranges for
is presented so that the user may adapt to their particular each detector material.
situation the fundamental procedures of the following tech-
1.6 This standard does not purport to address all of the
niques.
safety concerns, if any, associated with its use. It is the
1.1.1 Radiometric counting technique using pure cobalt,
responsibility of the user of this standard to establish appro-
pure gold, pure indium, cobalt-aluminum, alloy, gold-
priate safety, health and environmental practices and deter-
aluminum alloy, or indium-aluminum alloy.
mine the applicability of regulatory limitations prior to use.
1.1.2 Standard comparison technique using pure gold, or
1.7 This international standard was developed in accor-
gold-aluminum alloy, and
dance with internationally recognized principles on standard-
1.1.3 Secondarystandardcomparisontechniquesusingpure
ization established in the Decision on Principles for the
indium, indium-aluminum alloy, pure dysprosium, or
Development of International Standards, Guides and Recom-
dysprosium-aluminum alloy.
mendations issued by the World Trade Organization Technical
Barriers to Trade (TBT) Committee.
1.2 Thetechniquespresentedarelimitedtomeasurementsat
room temperatures. However, special problems when making
2. Referenced Documents
thermal-neutron fluence rate measurements in high-
2
temperature environments are discussed in 9.2. For those
2.1 ASTM Standards:
circumstances where the use of cadmium as a thermal shield is
E170Terminology Relating to Radiation Measurements and
undesirable because of potential spectrum perturbations or of
Dosimetry
temperatures above the melting point of cadmium, the method
E177Practice for Use of the Terms Precision and Bias in
described in Test Method E481 can be used in some cases.
ASTM Test Methods
Alternatively, gadolinium filters may be used instead of cad-
E181Test Methods for Detector Calibration andAnalysis of
mium. For high temperature applications in which aluminum
Radionuclides
alloys are unsuitable, other alloys such as cobalt-nickel or
E261Practice for Determining Neutron Fluence, Fluence
cobalt-vanadium have been used.
Rate, and Spectra by Radioactivation Techniques
E481Test Method for Measuring Neutron Fluence Rates by
1.3 This test method may be used to determine the equiva-
Radioactivation of Cobalt and Silver
lent 2200 m/s fluence rate. The accurate determination of the
actual thermal neutron fluence rate requires knowledge of the
3. Terminology
neutron temperature, and determination of the neutron tem-
perature is not within the scope of the standard.
3.1 cadmium ratio—see Terminology E170.
3.2 Calibration Techniques:
1
This method is under the jurisdiction of ASTM Committee E10 on Nuclear
Technology and Applicationsand is the direct responsibility of Subcommittee
2
E10.05 on Nuclear Radiation Metrology. For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Current edition approved Aug. 1, 2017. Published September 2017. Originally contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
approved in 1965. Last previous edition approved in 2013 as E262-13. DOI: Standardsvolume information, refer to the standard’s Document Summary page on
10.1520/E0262-17. the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
1
---------------------- Page: 1 ----------------------
E262 − 17
TABLE
...
This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
Designation: E262 − 13 E262 − 17
Standard Test Method for
Determining Thermal Neutron Reaction Rates and Thermal
1
Neutron Fluence Rates by Radioactivation Techniques
This standard is issued under the fixed designation E262; 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 (´) indicates an editorial change since the last revision or reapproval.
1. Scope
1.1 The purpose of this test method is to define a general procedure for determining an unknown thermal-neutron fluence rate
by neutron activation techniques. It is not practicable to describe completely a technique applicable to the large number of
experimental situations that require the measurement of a thermal-neutron fluence rate. Therefore, this method is presented so that
the user may adapt to histheir particular situation the fundamental procedures of the following techniques.
1.1.1 Radiometric counting technique using pure cobalt, pure gold, pure indium, cobalt-aluminum, alloy, gold-aluminum alloy,
or indium-aluminum alloy.
1.1.2 Standard comparison technique using pure gold, or gold-aluminum alloy, and
1.1.3 Secondary standard comparison techniques using pure indium, indium-aluminum alloy, pure dysprosium, or dysprosium-
aluminum alloy.
1.2 The techniques presented are limited to measurements at room temperatures. However, special problems when making
thermal-neutron fluence rate measurements in high-temperature environments are discussed in 9.2. For those circumstances where
the use of cadmium as a thermal shield is undesirable because of potential spectrum perturbations or of temperatures above the
melting point of cadmium, the method described in Test Method E481 can be used in some cases. Alternatively, gadolinium filters
may be used instead of cadmium. For high temperature applications in which aluminum alloys are unsuitable, other alloys such
as cobalt-nickel or cobalt-vanadium have been used.
1.3 This test method may be used to determine the equivalent 2200 m/s fluence rate. The accurate determination of the actual
thermal neutron fluence rate requires knowledge of the neutron temperature, and determination of the neutron temperature is not
within the scope of the standard.
1.4 The techniques presented are suitable only for neutron fields having a significant thermal neutron component, in which
moderating materials are present, and for which the average scattering cross section is large compared to the average absorption
cross section in the thermal neutron energy range.
1.5 Table 1 indicates the useful neutron-fluence ranges for each detector material.
1.6 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 safety, health and healthenvironmental practices and determine the
applicability of regulatory limitations prior to use.
1.7 This international standard was developed in accordance with internationally recognized principles on standardization
established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued
by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
2. Referenced Documents
2
2.1 ASTM Standards:
E170 Terminology Relating to Radiation Measurements and Dosimetry
E177 Practice for Use of the Terms Precision and Bias in ASTM Test Methods
E181 Test Methods for Detector Calibration and Analysis of Radionuclides
1
This method is under the jurisdiction of ASTM Committee E10 on Nuclear Technology and Applicationsand is the direct responsibility of Subcommittee E10.05 on
Nuclear Radiation Metrology.
Current edition approved Jan. 1, 2013Aug. 1, 2017. Published February 2013September 2017. Originally approved in 1965. Last previous edition approved in 20082013
as E262-08.-13. DOI: 10.1520/E0262-13.10.1520/E0262-17.
2
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
Standardsvolume information, refer to the standard’s Document Summary page on the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
1
---------------------- Page: 1 ----------------------
E262 − 17
TABLE 1 Useful Neutron Fluence Ranges of Foil Material
' Useful Range
Foil Material Form
...
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