Uranium-232

Properties and data of the isotope ²³²U.

Contents

General Data

Radioactive Decay

Parent Nuclides

Use

Isotones und Isobares

Literature

Uranium-232 is the radioisotope of the element Uranium, whose atomic nucleus has 140 neutrons in addition to the element-specific 92 protons, resulting in a mass number of 232.

See also: List of individual Uranium isotopes (and general data sources).

General data

Name of the isotope:Uranium-232; U-232Symbol:²³²U or 23292UMass number A:232 (= number of nucleons)Atomic number Z:92 (= number of protons)Neutrons N:140Nucleon pairing (Z - N):even - evenNuclear ratio (N/Z ratio):1.5217391304348 (= neutron-proton ratio)Neutron excess (N-Z):48Isotopic mass:232.0371549(1) u (atomic weight of Uranium-232)Nuclide mass:231.9866922 u (calculated nuclear mass without electrons)Mass excess:34.60957 MeVMass defect:1.895836284 u (per nucleus)Nuclear binding energy:1765.96012353 MeV (per nucleus)
7.61189708 MeV (average binding energy per nucleon)Separation energy:S_N = 7.2678(28) MeV (first neutron)
S_P = 6.1038(19) MeV (first proton)Half-life:68.9(4) aDecay constant λ:3.190110367083 × 10^-10 s^-1Specific activity α:828073016781.14 Bq g^-1
22.380351804896 Ci g^-1Spin and parity:
(nuclear angular momentum)0+Year of discovery:1949

Radioactive Decay

Half-life T_½ = 68.9(4) a respectively 2.1728 × 10⁹ seconds s.

Decay mode	Daughter	Probability	Decay energy	γ energy (intensity)
α	²²⁸Th	ca. 100 %	5.41363(9) MeV
SZ	div	trace

Parent Nuclides

Direct parent isotopes are: ²³⁶Pu, ²³²Np, ²³²Pa.

Use

Uranium-232 occurs in the thorium cycle and is used as a tracer in nuclear fuel. The U-232 decay chain produces a penetrating gamma radiation that is difficult to shield. With regard to thorium fuel, the presence of highly radiotoxic ²³²U means that the spent fuel must be handled using remote techniques in heavily shielded containment chambers.

Isotones and Isobars

The following table shows the atomic nuclei that are isotonic (same neutron number N = 140) and isobaric (same nucleon number A = 232) with Uranium-232. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.

Z	Isotone N = 140	Isobar A = 232
83	²²³Bi
84	²²⁴Po
85	²²⁵At
86	²²⁶Rn
87	²²⁷Fr	²³²Fr
88	²²⁸Ra	²³²Ra
89	²²⁹Ac	²³²Ac
90	²³⁰Th	²³²Th
91	²³¹Pa	²³²Pa
92	²³²U	²³²U
93	²³³Np	²³²Np
94	²³⁴Pu	²³²Pu
95	²³⁵Am	²³²Am
96	²³⁶Cm	²³²Cm
97	²³⁷Bk
98	²³⁸Cf

External data and identifiers

Adopted Levels, Gammas:NuDat 232U

Literature and References

[1] - Stephen F. Ashley, Geoffrey T. Parks, William J. Nuttall, Colin Boxall, Robin W. Grimes :
Thorium fuel has risks.
In: Nature, (2012), DOI 10.1038/492031a.

[2] - Andrzej Wojciechowski:
The U-232 production in thorium cycle.
In: Progress in Nuclear Energy, (2018), DOI 10.1016/j.pnucene.2018.03.011.

[3] - Joshua Rhodes, G. Ivan Maldonado:
Exploration of producing Uranium-232 for use as a tracer in uranium fuels.
In: Applied Radiation and Isotopes, (2022), DOI 10.1016/j.apradiso.2022.110275.