ASTM E693-23

Standard Practice for Characterizing Neutron Exposures in Iron and Low Alloy Steels in Terms of Displacements Per Atom (DPA)

SIGNIFICANCE AND USE
4.1 A pressure vessel surveillance program requires a methodology for relating radiation-induced changes in materials exposed in accelerated surveillance locations to the condition of the pressure vessel (see Practice E853). An important consideration is that the irradiation exposures be expressed in a unit that is physically related to the damage mechanisms.  
4.2 A major source of neutron radiation damage in metals is the displacement of atoms from their normal lattice sites. Hence, an appropriate damage exposure index is the number of times, on the average, that an atom has been displaced during an irradiation. This can be expressed as the total number of displaced atoms per unit volume, per unit mass, or per atom of the material. Displacements per atom is the most common way of expressing this quantity. The number of dpa associated with a particular irradiation depends on the amount of energy deposited in the material by the neutrons, and hence, depends on the neutron spectrum. (For a more extended discussion, see Practice E521.)  
4.3 No simple correspondence exists in general between dpa and a particular change in a material property. A reasonable starting point, however, for relative correlations of property changes produced in different neutron spectra is the dpa value associated with each environment. That is, the dpa values themselves provide a spectrum-sensitive index that may be a useful correlation parameter, or some function of the dpa values may affect correlation.  
4.4 Since dpa is a construct that depends on a model of the neutron interaction processes in the material lattice, as well as the cross section (probability) for each of these processes, the value of dpa would be different if improved models or cross sections are used. The calculated displacement cross section for ferritic iron, as given in this practice, is determined by the procedure given in 6.3. The currently recommended iron displacement cross section in this practice (Table 1) wa...
SCOPE
1.1 This practice describes a standard procedure for characterizing neutron irradiations of iron (and low alloy steels) in terms of the exposure index displacements per atom (dpa) for iron.  
1.2 Although the methods of this practice apply to any material for which a displacement cross section σd(E) is known (see Practice E521), this practice is written specifically for iron.  
1.3 It is assumed that the displacement cross section for iron is an adequate approximation for calculating displacements in steels that are mostly iron (95 to 100 %) in radiation fields for which secondary damage processes are not important.  
1.4 Procedures analogous to this one can be formulated for calculating dpa in charged particle irradiations. (See Practice E521.)  
1.5 The application of this practice requires knowledge of the total neutron fluence and flux spectrum. Refer to Practice E521 for determining these quantities.  
1.6 The correlation of radiation effects data is beyond the scope of this practice.  
1.7 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, health, and environmental practices and determine the applicability of regulatory limitations prior to use.  
1.8 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.

General Information

• Status: Published
• Publication Date: 31-Dec-2022
• ICS: 77.080.20 - Steels
• Technical Committee: E10 - Nuclear Technology and Applications
• Drafting Committee: E10.05 - Nuclear Radiation Metrology

Standards Content (Sample)

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: E693 − 23
Standard Practice for
Characterizing Neutron Exposures in Iron and Low Alloy
1
Steels in Terms of Displacements Per Atom (DPA)
This standard is issued under the fixed designation E693; 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 2. Referenced Documents
2
2.1 ASTM Standards:
1.1 This practice describes a standard procedure for charac-
E170 Terminology Relating to Radiation Measurements and
terizing neutron irradiations of iron (and low alloy steels) in
Dosimetry
terms of the exposure index displacements per atom (dpa) for
E521 Practice for Investigating the Effects of Neutron Ra-
iron.
diation Damage Using Charged-Particle Irradiation
1.2 Although the methods of this practice apply to any
E706 Master Matrix for Light-Water Reactor Pressure Vessel
material for which a displacement cross sectionσ (E) is known
Surveillance Standards
d
(see Practice E521), this practice is written specifically for iron.
E821 Practice for Measurement of Mechanical Properties
During Charged-Particle Irradiation
1.3 It is assumed that the displacement cross section for iron
E853 Practice for Analysis and Interpretation of Light-Water
is an adequate approximation for calculating displacements in
Reactor Surveillance Neutron Exposure Results
steels that are mostly iron (95 to 100 %) in radiation fields for
which secondary damage processes are not important.
3. Terminology
1.4 Procedures analogous to this one can be formulated for
3.1 Definitions for terms used in this practice can be found
calculating dpa in charged particle irradiations. (See Practice
in Terminology E170.
E521.)
4. Significance and Use
1.5 The application of this practice requires knowledge of
4.1 A pressure vessel surveillance program requires a meth-
the total neutron fluence and flux spectrum. Refer to Practice
odology for relating radiation-induced changes in materials
E521 for determining these quantities.
exposed in accelerated surveillance locations to the condition
1.6 The correlation of radiation effects data is beyond the
of the pressure vessel (see Practice E853). An important
scope of this practice.
consideration is that the irradiation exposures be expressed in
a unit that is physically related to the damage mechanisms.
1.7 This standard does not purport to address all of the
safety concerns, if any, associated with its use. It is the
4.2 A major source of neutron radiation damage in metals is
responsibility of the user of this standard to establish appro-
the displacement of atoms from their normal lattice sites.
priate safety, health, and environmental practices and deter-
Hence, an appropriate damage exposure index is the number of
mine the applicability of regulatory limitations prior to use. times, on the average, that an atom has been displaced during
an irradiation. This can be expressed as the total number of
1.8 This international standard was developed in accor-
displaced atoms per unit volume, per unit mass, or per atom of
dance with internationally recognized principles on standard-
the material. Displacements per atom is the most common way
ization established in the Decision on Principles for the
of expressing this quantity. The number of dpa associated with
Development of International Standards, Guides and Recom-
a particular irradiation depends on the amount of energy
mendations issued by the World Trade Organization Technical
deposited in the material by the neutrons, and hence, depends
Barriers to Trade (TBT) Committee.
on the neutron spectrum. (For a more extended discussion, see
Practice E521.)
1
This practice is under the jurisdiction of ASTM Committee E10 on Nuclear
Technology and Applications and 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 Jan. 1, 2023. Published January 2023. Originally contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
approved in 1979. Last previous edition approved in 2017 as E693 – 17. DOI: Standards volume information, refer to the standard’s Document Summary page on
10.1520/E0693-23. the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
1

---------------------- Page: 1 ----------------------
E693 − 23
4.3 No simple correspondence exists in general between dpa 5.2.1 If the
...

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: E693 − 17 E693 − 23
Standard Practice for
Characterizing Neutron Exposures in Iron and Low Alloy
1
Steels in Terms of Displacements Per Atom (DPA)
This standard is issued under the fixed designation E693; 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 This practice describes a standard procedure for characterizing neutron irradiations of iron (and low alloy steels) in terms of
the exposure index displacements per atom (dpa) for iron.
1.2 Although the methods of this practice apply to any material for which a displacement cross section σ (E) is known (see
d
Practice E521), this practice is written specifically for iron.
1.3 It is assumed that the displacement cross section for iron is an adequate approximation for calculating displacements in steels
that are mostly iron (95 to 100 %) in radiation fields for which secondary damage processes are not important.
1.4 Procedures analogous to this one can be formulated for calculating dpa in charged particle irradiations. (See Practice E521.)
1.5 The application of this practice requires knowledge of the total neutron fluence and flux spectrum. Refer to Practice E521 for
determining these quantities.
1.6 The correlation of radiation effects data is beyond the scope of this practice.
1.7 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, health, and environmental practices and determine the applicability of
regulatory limitations prior to use.
1.8 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
E521 Practice for Investigating the Effects of Neutron Radiation Damage Using Charged-Particle Irradiation
E706 Master Matrix for Light-Water Reactor Pressure Vessel Surveillance Standards
1
This practice 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.
Current edition approved Aug. 1, 2017Jan. 1, 2023. Published September 2017January 2023. Originally approved in 1979. Last previous edition approved in 20122017
ɛ1
as E693 – 12E693 – 17. . DOI: 10.1520/E0693-17.10.1520/E0693-23.
2
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM Standards
volume 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 ----------------------
E693 − 23
E821 Practice for Measurement of Mechanical Properties During Charged-Particle Irradiation
E853 Practice for Analysis and Interpretation of Light-Water Reactor Surveillance Neutron Exposure Results
3. Terminology
3.1 Definitions for terms used in this practice can be found in Terminology E170.
4. Significance and Use
4.1 A pressure vessel surveillance program requires a methodology for relating radiation-induced changes in materials exposed
in accelerated surveillance locations to the condition of the pressure vessel (see Practice E853). An important consideration is that
the irradiation exposures be expressed in a unit that is physically related to the damage mechanisms.
4.2 A major source of neutron radiation damage in metals is the displacement of atoms from their normal lattice sites. Hence, an
appropriate damage exposure index is the number of times, on the average, that an atom has been displaced during an irradiation.
This can be expressed as the total number of displaced atoms per unit volume, per unit mass, or per atom of the material.
Displacements per atom is the most common way of expressing this quantity. The number of dpa associated with a particular
irradiation depends on the amount of energy deposited in the material by the
...