ASTM E262-03

Standard Method for Determining Thermal Neutron Reaction and Fluence Rates by Radioactivation Techniques

SIGNIFICANCE AND USE
This method can be extended to use any material that has the necessary nuclear and activation properties that suit the experimenter’particular situation. No attempt has been made to fully describe the myriad problems of absolute 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 method does offer a referee method (the standard gold foil irradiation at National Institute of Standards and Technology (NIST) to aid the experimenter when he is in doubt of his ability to measure an absolute thermal fluence rate.
The standard foil 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 4). One important feature of this technique is that it eliminates the need for absolute counting.
SCOPE
1.1 The purpose of this 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 his particular situation the fundamental procedures of the following techniques.
1.1.1 Absolute counting technique using pure cobalt, pure gold, or cobalt-aluminum or gold-aluminum alloy.
1.1.2 Standard foil technique using pure gold, or gold-aluminum alloy, and
1.1.3 Secondary standard foil techniques using pure indium, indium-aluminum alloy, and 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 . 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 E 481 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 indicates the useful neutron-fluence ranges for each detector material.
1.4 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.

General Information

• Status: Historical
• Publication Date: 09-Feb-2003
• ICS: 17.240 - Radiation measurements
• ICS: 27.120.30 - Fissile materials and nuclear fuel technology
• Technical Committee: E10 - Nuclear Technology and Applications
• Drafting Committee: E10.05 - Nuclear Radiation Metrology

Relations

• Replaces: ASTM E262-97 - Standard Method for Determining Thermal Neutron Reaction and Fluence Rates by Radioactivation Techniques
• Effective Date: 10-Feb-2003
• Replaced By: ASTM E262-08 - Standard Test Method for Determining Thermal Neutron Reaction Rates and Thermal Neutron Fluence Rates by Radioactivation Techniques
• Effective Date: 01-Nov-2008
• Referred By: ASTM E704-19 - Standard Test Method for Measuring Reaction Rates by Radioactivation of Uranium-238
• Effective Date: 10-Feb-2003
• Referred By: ASTM E1005-21 - Standard Test Method for Application and Analysis of Radiometric Monitors for Reactor Vessel Surveillance
• Effective Date: 10-Feb-2003
• Referred By: ASTM E944-19 - Standard Guide for Application of Neutron Spectrum Adjustment Methods in Reactor Surveillance
• Effective Date: 10-Feb-2003
• Referred By: ASTM E721-22 - Standard Guide for Determining Neutron Energy Spectra from Neutron Sensors for Radiation-Hardness Testing of Electronics
• Effective Date: 10-Feb-2003
• Referred By: ASTM E720-23 - Standard Guide for Selection and Use of Neutron Sensors for Determining Neutron Spectra Employed in Radiation-Hardness Testing of Electronics
• Effective Date: 10-Feb-2003
• Referred By: ASTM E705-18 - Standard Test Method for Measuring Reaction Rates by Radioactivation of Neptunium-237
• Effective Date: 10-Feb-2003
• Referred By: ASTM E481-23 - Standard Practice for Measuring Neutron Fluence Rates by Radioactivation of Cobalt and Silver
• Effective Date: 10-Feb-2003
• Referred By: ASTM E1854-19 - Standard Practice for Ensuring Test Consistency in Neutron-Induced Displacement Damage of Electronic Parts
• Effective Date: 10-Feb-2003
• Referred By: ASTM E2006-22 - Standard Guide for Benchmark Testing of Light Water Reactor Calculations
• Effective Date: 10-Feb-2003
• Referred By: ASTM E1297-18 - Standard Test Method for Measuring Fast-Neutron Reaction Rates by Radioactivation of Niobium
• Effective Date: 10-Feb-2003
• Referred By: ASTM E261-16(2021) - Standard Practice for Determining Neutron Fluence, Fluence Rate, and Spectra by Radioactivation Techniques
• Effective Date: 10-Feb-2003

Standards Content (Sample)

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information
Designation:E262–03
Standard Test Method for
Determining Thermal Neutron Reaction and Fluence Rates
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by Radioactivation Techniques
This standard is issued under the fixed designation E 262; 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.
1. Scope 2. Referenced Documents
1.1 The purpose of this method is to define a general 2.1 ASTM Standards:
procedure for determining an unknown thermal neutron- E 177 Practice for Use of the Terms Precision and Bias in
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fluence rate by neutron activation techniques. It is not practi- ASTM Test Methods
cabletodescribecompletelyatechniqueapplicabletothelarge E 181 Test Methods for Detector Calibration and Analysis
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number of experimental situations that require the measure- of Radionuclides
ment of a thermal-neutron fluence rate. Therefore, this method E 261 Practice for Determining Neutron Fluence Rate, Flu-
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is presented so that the user may adapt to his particular ence, and Spectra by Radioactivation Techniques
situation the fundamental procedures of the following tech- E 481 Test Method for Measuring Neutron Fluence Rate by
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niques. Radioactivation of Cobalt and Silver
1.1.1 Absolute counting technique using pure cobalt, pure
3. Significance and Use
gold, or cobalt-aluminum or gold-aluminum alloy.
3.1 This method can be extended to use any material that
1.1.2 Standard foil technique using pure gold, or gold-
aluminum alloy, and has the necessary nuclear and activation properties that suit the
experimenter’s particular situation. No attempt has been made
1.1.3 Secondary standard foil techniques using pure indium,
indium-aluminum alloy, and dysprosium-aluminum alloy. to fully describe the myriad problems of absolute counting
techniques, neutron-fluence depression, and thick-foil self-
1.2 Thetechniquespresentedarelimitedtomeasurementsat
room temperatures. However, special problems when making shielding. It is assumed that the experimenter will refer to
existing literature on these subjects. This method does offer a
thermal-neutron fluence rate measurements in high-
referee method (the standard gold foil irradiation at National
temperature environments are discussed in 8.2. For those
circumstances where the use of cadmium as a thermal shield is Institute of Standards and Technology (NIST) to aid the
experimenter when he is in doubt of his ability to measure an
undesirable because of potential spectrum perturbations or of
temperatures above the melting point of cadmium, the method absolute thermal fluence rate.
3.2 The standard foil technique uses a set of foils that are as
described in Test Method E 481 can be used in some cases.
Alternatively, gadolinium filters may be used instead of cad- nearly identical as possible in shape and mass. The foils are
fabricated from any material that activates by an (n, g)
mium. For high temperature applications in which aluminum
alloys are unsuitable, other alloys such as cobalt-nickel or reaction, preferably having a cross section approximately
inversely proportional to neutron speed in the thermal energy
cobalt-vanadium have been used.
1.3 Table 1 indicates the useful neutron-fluence ranges for range. Some of the foils are irradiated in a known neutron field
(at NIST) or other standards laboratory). The foils are counted
each detector material.
1.4 This standard does not purport to address all of the in a fixed geometry on a stable radiation-detecting instrument.
Theneutroninducedreactionrateofthefoilsiscomputedfrom
safety concerns, if any, associated with its use. It is the
responsibility of the user of this standard to establish appro- the counting data, and the ratio of the known neutron fluence
rate to the computed reaction rate is determined. For any given
priate safety and health practices and determine the applica-
bility of regulatory limitations prior to use. 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
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fluencerateintheunknownfieldcanbeobtainedbycomparing
This method is under the jurisdiction of ASTM Committee E10 on Nuclear
Technology and Applications and is the direct responsibility of Subcommittee
E10.05 on Nuclear Radiation Metrology.
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Current edition approved Feb. 10, 2003. Published March 2003. Originally Annual Book of ASTM Standards, Vol 14.02.
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approved in 1965 T. Last previous edition approved as E 262 – 97. Annual Book of ASTM Standards, Vol 12.02.
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