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Radionuclide Dosimetric Data Sheets
Uranium-231
Summary data
General
Classification
Isotope: U-231
Atomic number (Z): 92
Mass number (A): 231
Neutron number (N): 139
Radioactive decay
Decay modes: α, Electron capture
Half-life: 4.2 [d]
Decay constant: 1.9101e-06 [1/s]
Daughters: Pa-231 (100.0%), Th-227 (0.004%)
Radioactive daughters: Pa-231, Th-227
Dosimetric constants
Mean alpha energy: 0.0002 [MeV]
Mean electron energy: 0.08467 [MeV]
Mean photon energy: 0.08964 [MeV]
Air kerma rate constant, Γ10: 3.172e-17 [Gy·m2/Bq·s]
Air kerma coefficient, Kair: 3.172e-17 [Gy·m2/Bq·s]
Equilibrium dose constant for weakly-penetrating radiations (α and/or
electrons), Δwp: 1.360e-14 [Gy·kg/Bq·s]
Equilibrium dose constant for alphas, Δα: 3.204e-17
[Gy·kg/Bq·s]
Equilibrium dose constant for betas/electrons, Δβ-,β+,e-:
1.357e-14 [Gy·kg/Bq·s]
Equilibrium dose constant for photons, Δp: 1.436e-14
[Gy·kg/Bq·s]
Dose point kernels (plot)
Dose point kernel source: Graves, et al. Medical Physics. 2019 Nov.; 46(11):5284-5293.
Note: Bins are spaced every 0.1 mm until a radius of 10 cm, and every 1 mm until a radius of 2 m.
Download tabulated dose point kernel file here: www.mirdsoft.org/products/MIRDspecs/U-231 DPK.csv
Summary spectra (plot)
Spectra source: ICRP Publication 107: Nuclear Decay Data for Dosimetric Calculations. Ann. ICRP 2008, 38 (3).
Download tabulated summary spectra file here: www.mirdsoft.org/products/MIRDspecs/U-231 Summary Spectrum.csv
Tabulated data
Summary spectra (table)
Spectra source: ICRP Publication 107: Nuclear Decay Data for Dosimetric Calculations. Ann. ICRP 2008, 38 (3).
Note: Radiations with yield < 0.01 are excluded from the table, but are available in the linked *.csv data.
Download tabulated summary spectra file here: www.mirdsoft.org/products/MIRDspecs/U-231 Summary Spectrum.csv
|
Energy [MeV] |
Yield [#/nt] if > 0.01 |
Radiation type |
|
7.65216e-05 |
3.374e+01 |
X-ray |
|
3.15895e-03 |
1.944e-01 |
X-ray |
|
1.14081e-02 |
3.112e-02 |
X-ray |
|
1.31269e-02 |
5.132e-02 |
X-ray |
|
1.32994e-02 |
4.510e-01 |
X-ray |
|
1.59993e-02 |
1.027e-02 |
X-ray |
|
1.60398e-02 |
9.387e-02 |
X-ray |
|
1.61112e-02 |
2.203e-02 |
X-ray |
|
1.66446e-02 |
1.739e-02 |
X-ray |
|
1.67859e-02 |
2.581e-01 |
X-ray |
|
1.69536e-02 |
1.967e-02 |
X-ray |
|
1.96582e-02 |
5.794e-02 |
X-ray |
|
2.02959e-02 |
1.097e-02 |
X-ray |
|
2.56500e-02 |
1.460e-01 |
Gamma |
|
8.42300e-02 |
7.300e-02 |
Gamma |
|
9.26782e-02 |
1.745e-01 |
X-ray |
|
9.63371e-02 |
2.806e-01 |
X-ray |
|
1.02300e-01 |
1.256e-02 |
Gamma |
|
1.08078e-01 |
3.226e-02 |
X-ray |
|
1.08921e-01 |
6.301e-02 |
X-ray |
|
1.12089e-01 |
1.620e-02 |
X-ray |
|
6.46633e-05 |
8.218e+00 |
Auger electron |
|
1.56144e-04 |
5.526e-02 |
Auger electron |
|
1.65010e-04 |
8.921e+00 |
Auger electron |
|
1.93398e-04 |
5.042e+00 |
Auger electron |
|
5.14018e-04 |
1.464e+00 |
Auger electron |
|
1.29803e-03 |
4.813e-01 |
Auger electron |
|
1.32700e-03 |
2.360e-01 |
Conversion electron |
|
2.37978e-03 |
2.914e+00 |
Auger electron |
|
2.82493e-03 |
5.252e-01 |
Auger electron |
|
3.42338e-03 |
3.053e-02 |
Auger electron |
|
4.53700e-03 |
9.041e-02 |
Conversion electron |
|
5.24800e-03 |
1.679e-01 |
Conversion electron |
|
8.90700e-03 |
2.218e-01 |
Conversion electron |
|
9.82260e-03 |
7.114e-01 |
Auger electron |
|
1.30363e-02 |
3.571e-01 |
Auger electron |
|
1.39106e-02 |
2.076e-01 |
Conversion electron |
|
1.62790e-02 |
4.223e-02 |
Auger electron |
|
1.80700e-02 |
7.281e-02 |
Conversion electron |
|
2.14906e-02 |
1.259e-01 |
Conversion electron |
|
2.56500e-02 |
4.184e-02 |
Conversion electron |
|
3.74370e-02 |
1.003e-02 |
Conversion electron |
|
3.81480e-02 |
2.905e-01 |
Conversion electron |
|
4.18070e-02 |
2.422e-01 |
Conversion electron |
|
5.43906e-02 |
1.500e-01 |
Conversion electron |
|
5.85500e-02 |
5.225e-02 |
Conversion electron |
|
6.31170e-02 |
6.091e-02 |
Conversion electron |
|
6.38280e-02 |
3.947e-02 |
Conversion electron |
|
6.74870e-02 |
3.681e-02 |
Conversion electron |
|
7.36405e-02 |
1.227e-02 |
Auger electron |
|
8.00706e-02 |
3.372e-02 |
Conversion electron |
|
8.42300e-02 |
1.159e-02 |
Conversion electron |
Useful Links
Isotope decay characteristics are periodically updated as better measurements can be made - changes that may not be reflected on this page. Please see useful links:
National Nuclear Data Center (NNDC): https://www.nndc.bnl.gov/nudat3/mird/
International Atomic Energy Agency (IAEA) Livechart: https://www-nds.iaea.org/relnsd/vcharthtml/VChartHTML.html
Reference Links
ICRP Report 107: https://www.icrp.org/publication.asp?id=ICRP%20Publication%20107
Graves et al. Dose Point Kernels: https://doi.org/10.1002/mp.13789
MIRD Decay Schemes 2nd Edition: https://sites.snmmi.org/SNMMI-MAIN/iCore/Store/StoreLayouts/Item_Detail.aspx?iProductCode=0-932004-80-6
MIRDsoft MIRDspecs version 20250101 (www.mirdsoft.org)
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