ASTM E693 - 12

    Standard Practice for Characterizing Neutron Exposures in Iron and Low Alloy Steels in Terms of Displacements Per Atom (DPA), E 706(ID)

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

    Book of Standards Volume: 12.02


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    ASTM E693

    Significance and Use

    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.

    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.)

    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

    BinEngA (MeV)σd (barns)BinEngA (MeV)σd (barns)BinEngA (MeV)σd (barns)
    10.100E-09158.354320.1050E-09154.620930.110E-09151.1395
    40.1150E-09147.889550.120E-09144.105460.1275E-09139.9202
    70.1350E-09136.086080.1425E-09132.544590.150E-09128.7502
    100.160E-09124.7860110.170E-09121.1728120.180E-09117.8527
    130.190E-09114.8137140.200E-09111.9561150.210E-09109.3199
    160.220E-09106.8646170.230E-09104.5694180.240E-09101.8930
    190.2550E-0998.93331200.270E-0996.65981210.280E-0994.12717
    220.300E-0991.05218230.320E-0988.24872240.340E-0985.68787
    250.360E-0983.33912260.380E-0981.17265270.400E-0978.92472
    280.4250E-0976.63646290.450E-0974.53734300.4750E-0972.59930
    310.500E-0970.81827320.5250E-0969.14790330.550E-0967.59222
    340.5750E-0966.13822350.600E-0964.64189360.630E-0963.12039
    370.660E-0961.70157380.690E-0960.37332390.720E-0958.92732
    400.760E-0957.39681410.800E-0955.97892420.840E-0954.65984
    430.880E-0953.43220440.920E-0952.28703450.960E-0951.21545
    460.100E-0850.07727470.1050E-0848.89598480.110E-0847.79609
    490.1150E-0846.76870500.120E-0845.57125510.1275E-0844.25006
    520.1350E-0843.03653530.1425E-0841.91761540.150E-0840.71708
    550.160E-0839.46333560.170E-0838.32018570.180E-0837.26968
    580.190E-0836.30967590.200E-0835.40710600.210E-0834.57391
    610.220E-0833.79705620.230E-0833.06956630.240E-0832.22424
    640.2550E-0831.28942650.270E-0830.57002660.280E-0829.76999
    670.300E-0828.79791680.320E-0827.91048690.340E-0827.10139
    700.360E-0826.35879710.380E-0825.67357720.400E-0824.96309
    730.4250E-0824.23960740.450E-0823.57548750.4750E-0822.96268
    760.500E-0822.39920770.5250E-0821.87094780.550E-0821.37982
    790.5750E-0820.91994800.600E-0820.44705810.630E-0819.96509
    820.660E-0819.51724830.690E-0819.09670840.720E-0818.63984
    850.760E-0818.15581860.800E-0817.70708870.840E-0817.29049
    880.880E-0816.90205890.920E-0816.54074900.960E-0816.20166
    910.100E-0715.84242920.1050E-0715.46908930.110E-0715.12094
    940.1150E-0714.79594950.120E-0714.41855960.1275E-0714.00095
    970.13050E-0713.61661980.1425E-0713.26338990.150E-0712.88403
    1000.160E-0712.487591010.170E-0712.126331020.180E-0711.79428
    1030.190E-0711.490391040.200E-0711.207601050.210E-0710.94298
    1060.220E-0710.697451070.230E-0710.468041080.240E-0710.20132
    1090.2550E-079.9067171100.270E-079.6794491110.280E-079.427035
    1120.300E-079.1187451130.320E-078.8388191140.340E-078.582926
    1150.360E-078.3479621160.380E-078.1316181170.400E-077.907534
    1180.4250E-077.6788091190.450E-077.4688051200.4750E-077.276812
    1210.500E-077.0975981220.5250E-076.9307671230.550E-076.775607
    1240.5750E-076.6307011250.600E-076.4820831260.630E-076.330435
    1270.660E-076.1889631280.690E-076.0566311290.720E-075.913148
    1300.760E-075.7602981310.800E-075.6186171320.840E-075.486900
    1330.880E-075.3643371340.920E-075.2500291350.960E-075.143171
    1360.100E-065.0292541370.1050E-064.9114271380.110E-064.801945
    1390.1150E-064.6997141400.120E-064.5815851410.1275E-064.450361
    1420.1350E-064.3296141430.1425E-064.2182221440.150E-064.099185
    1450.160E-063.9743041460.170E-063.8604021470.180E-063.756055
    1480.190E-063.6607611490.200E-063.5713131500.210E-063.488699
    1510.220E-063.4116161520.230E-063.3394661530.240E-063.256051
    1540.2550E-063.1632761550.270E-063.0916281560.280E-063.013147
    1570.300E-062.9169451580.320E-062.8294031590.340E-062.749808
    1600.360E-062.6767501610.380E-062.6088351620.400E-062.527930
    1630.4250E-062.4408971640.450E-062.3743841650.4750E-062.313606
    1660.500E-062.2574621670.5250E-062.2053311680.550E-062.154114
    1690.5750E-062.1087331700.600E-062.0601341710.630E-062.011735
    1720.660E-061.9660451730.690E-061.9235861740.720E-061.877395
    1750.760E-061.8285961760.800E-061.7830081770.840E-061.741254
    1780.880E-061.7034171790.920E-061.6677921800.960E-061.632082
    1810.100E-051.5957541820.1050E-051.5587201830.110E-051.522295
    1840.1150E-051.4902001850.120E-051.4515541

    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 and health practices and determine the applicability of regulatory limitations prior to use.


    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 Neutron Radiation Damage Simulation by 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, E706(IA)


    ICS Code

    ICS Number Code 77.080.20 (Steels)

    UNSPSC Code

    UNSPSC Code 11101704(Steel)


    DOI: 10.1520/E0693-12

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