ASTM E693 - 17

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

    Active Standard ASTM E693 | Developed by Subcommittee: E10.05

    Book of Standards Volume: 12.02


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    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.

    TABLE 1 ENDF/B-VI-based Iron Displacement Cross Section

    Bin

    EngA (MeV)

    σd (barns)

    Bin

    EngA (MeV)

    σd (barns)

    Bin

    EngA (MeV)

    σd (barns)

    1

    0.100E-09

    158.3543

    2

    0.1050E-09

    154.6209

    3

    0.110E-09

    151.1395

    4

    0.1150E-09

    147.8895

    5

    0.120E-09

    144.1054

    6

    0.1275E-09

    139.9202

    7

    0.1350E-09

    136.0860

    8

    0.1425E-09

    132.5445

    9

    0.150E-09

    128.7502

    10

    0.160E-09

    124.7860

    11

    0.170E-09

    121.1728

    12

    0.180E-09

    117.8527

    13

    0.190E-09

    114.8137

    14

    0.200E-09

    111.9561

    15

    0.210E-09

    109.3199

    16

    0.220E-09

    106.8646

    17

    0.230E-09

    104.5694

    18

    0.240E-09

    101.8930

    19

    0.2550E-09

    98.93331

    20

    0.270E-09

    96.65981

    21

    0.280E-09

    94.12717

    22

    0.300E-09

    91.05218

    23

    0.320E-09

    88.24872

    24

    0.340E-09

    85.68787

    25

    0.360E-09

    83.33912

    26

    0.380E-09

    81.17265

    27

    0.400E-09

    78.92472

    28

    0.4250E-09

    76.63646

    29

    0.450E-09

    74.53734

    30

    0.4750E-09

    72.59930

    31

    0.500E-09

    70.81827

    32

    0.5250E-09

    69.14790

    33

    0.550E-09

    67.59222

    34

    0.5750E-09

    66.13822

    35

    0.600E-09

    64.64189

    36

    0.630E-09

    63.12039

    37

    0.660E-09

    61.70157

    38

    0.690E-09

    60.37332

    39

    0.720E-09

    58.92732

    40

    0.760E-09

    57.39681

    41

    0.800E-09

    55.97892

    42

    0.840E-09

    54.65984

    43

    0.880E-09

    53.43220

    44

    0.920E-09

    52.28703

    45

    0.960E-09

    51.21545

    46

    0.100E-08

    50.07727

    47

    0.1050E-08

    48.89598

    48

    0.110E-08

    47.79609

    49

    0.1150E-08

    46.76870

    50

    0.120E-08

    45.57125

    51

    0.1275E-08

    44.25006

    52

    0.1350E-08

    43.03653

    53

    0.1425E-08

    41.91761

    54

    0.150E-08

    40.71708

    55

    0.160E-08

    39.46333

    56

    0.170E-08

    38.32018

    57

    0.180E-08

    37.26968

    58

    0.190E-08

    36.30967

    59

    0.200E-08

    35.40710

    60

    0.210E-08

    34.57391

    61

    0.220E-08

    33.79705

    62

    0.230E-08

    33.06956

    63

    0.240E-08

    32.22424

    64

    0.2550E-08

    31.28942

    65

    0.270E-08

    30.57002

    66

    0.280E-08

    29.76999

    67

    0.300E-08

    28.79791

    68

    0.320E-08

    27.91048

    69

    0.340E-08

    27.10139

    70

    0.360E-08

    26.35879

    71

    0.380E-08

    25.67357

    72

    0.400E-08

    24.96309

    73

    0.4250E-08

    24.23960

    74

    0.450E-08

    23.57548

    75

    0.4750E-08

    22.96268

    76

    0.500E-08

    22.39920

    77

    0.5250E-08

    21.87094

    78

    0.550E-08

    21.37982

    79

    0.5750E-08

    20.91994

    80

    0.600E-08

    20.44705

    81

    0.630E-08

    19.96509

    82

    0.660E-08

    19.51724

    83

    0.690E-08

    19.09670

    84

    0.720E-08

    18.63984

    85

    0.760E-08

    18.15581

    86

    0.800E-08

    17.70708

    87

    0.840E-08

    17.29049

    88

    0.880E-08

    16.90205

    89

    0.920E-08

    16.54074

    90

    0.960E-08

    16.20166

    91

    0.100E-07

    15.84242

    92

    0.1050E-07

    15.46908

    93

    0.110E-07

    15.12094

    94

    0.1150E-07

    14.79594

    95

    0.120E-07

    14.41855

    96

    0.1275E-07

    14.00095

    97

    0.13050E-07

    13.61661

    98

    0.1425E-07

    13.26338

    99

    0.150E-07

    12.88403

    100

    0.160E-07

    12.48759

    101

    0.170E-07

    12.12633

    102

    0.180E-07

    11.79428

    103

    0.190E-07

    11.49039

    104

    0.200E-07

    11.20760

    105

    0.210E-07

    10.94298

    106

    0.220E-07

    10.69745

    107

    0.230E-07

    10.46804

    108

    0.240E-07

    10.20132

    109

    0.2550E-07

    9.906717

    110

    0.270E-07

    9.679449

    111

    0.280E-07

    9.427035

    112

    0.300E-07

    9.118745

    113

    0.320E-07

    8.838819

    114

    0.340E-07

    8.582926

    115

    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 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.


    2. Referenced Documents (purchase separately) The documents listed below are referenced within the subject standard but are not provided as part of the standard.

    ASTM Standards

    E170 Terminology Relating to Radiation Measurements and Dosimetry

    E521 Practice for Investigating the Effects of Neutron Radiation Damage Using Charged-Particle Irradiation

    E821 Practice for Measurement of Mechanical Properties During Charged-Particle Irradiation

    E853 Practice for Analysis and Interpretation of Light-Water Reactor Surveillance Results


    ICS Code

    ICS Number Code 77.080.20 (Steels)

    UNSPSC Code

    UNSPSC Code 11101704(Steel)


    Referencing This Standard
    Link Here
    Link to Active (This link will always route to the current Active version of the standard.)

    DOI: 10.1520/E0693-17

    Citation Format

    ASTM E693-17, Standard Practice for Characterizing Neutron Exposures in Iron and Low Alloy Steels in Terms of Displacements Per Atom (DPA), ASTM International, West Conshohocken, PA, 2017, www.astm.org

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