Uranium-232

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Uranium-232, ²³²U

General
228Th
Isotopes of uranium Complete table of nuclides

Uranium-232 (²³²
U
) is an isotope of uranium. It has a half-life of around 69 years and is a side product in the

(a daughter of ²³²U, produced relatively quickly) makes the ²³³U contaminated with it more difficult to handle.

Production of ²³³U (through the neutron irradiation of ²³²Th) invariably produces small amounts of ²³²U as an impurity, because of parasitic (n,2n) reactions on

:

²³²Th (n,γ) ²³³Th (β⁻) ²³³Pa (β⁻) ²³³U (n,2n) ²³²U

²³²Th (n,γ) ²³³Th (β⁻) ²³³Pa (n,2n) ²³²Pa (β⁻) ²³²U

²³²Th (n,2n) ²³¹Th (β⁻) ²³¹Pa (n,γ) ²³²Pa (β⁻) ²³²U

Another channel involves neutron capture reaction on small amounts of thorium-230, which is a tiny fraction of natural thorium present due to the decay of uranium-238:

²³⁰Th (n,γ) ²³¹Th (β⁻) ²³¹Pa (n,γ) ²³²Pa (β⁻) ²³²U

The decay chain of ²³²U quickly yields strong gamma radiation emitters:^[1]

²³²U (α, 68.9 years)

²²⁸Th (α, 1.9 year)

²²⁴Ra (α, 3.6 day, 0.24 MeV) (from this point onwards, the decay chain is identical to that of

²³²Th

; thorium-232 is nevertheless much less dangerous because its extremely long half-life of about 14-15 billion years means that not as much of its dangerous daughters builds up)

²²⁰Rn (α, 55 s, 0.54 MeV)

²¹⁶Po (α, 0.15 s)

²¹²Pb (β⁻, 10.64 h)

²¹²Bi (α, 61 min, 0.78 MeV)

²⁰⁸Tl (β⁻, 3 min, 2.6 MeV) (35.94% branching ratio)

²⁰⁸Pb (stable)

This makes manual handling in a glove box with only light shielding (as commonly done with plutonium) too hazardous, (except possibly in a short period immediately following chemical separation of the uranium from its decay products) and instead requiring remote manipulation for fuel fabrication.

Unusually for an isotope with even

(thermal 73 b, resonance integral 280 b).

Lighter: uranium-231	Uranium-232 is an isotope of uranium	Heavier: uranium-233
protactinium-232 (β− )	Decay chain of uranium-232	thorium-228 (α)

References