Uranium-233
229Th | |
Isotopes of uranium Complete table of nuclides |
Uranium-233 (233U or U-233) is a
Uranium-233 is produced by the
233U usually fissions on
Fissile material
In 1946, the public first became informed of uranium-233 bred from thorium as "a third available source of nuclear energy and atom bombs" (in addition to uranium-235 and plutonium-239), following a United Nations report and a speech by Glenn T. Seaborg.[3][4]
The United States produced, over the course of the Cold War, approximately 2 metric tons of uranium-233, in varying levels of chemical and isotopic purity.[2] These were produced at the Hanford Site and Savannah River Site in reactors that were designed for the production of plutonium-239.[5]
Nuclear fuel
Uranium-233 has been used as a fuel in several different reactor types, and is proposed as a fuel for several new designs
The long-term strategy of the nuclear power program of India, which has substantial thorium reserves, is to move to a nuclear program breeding uranium-233 from thorium feedstock.
Energy released
The fission of one atom of uranium-233 generates 197.9 MeV = 3.171·10−11 J (i.e. 19.09 TJ/mol = 81.95 TJ/kg = 22764 MWh/kg that is 1.8 million times more than the same mass of diesel).[6]
Source | Average energy released (MeV) |
---|---|
Instantaneously released energy | |
Kinetic energy of fission fragments | 168.2 |
Kinetic energy of prompt neutrons | 4.8 |
Energy carried by prompt γ-rays | 7.7 |
Energy from decaying fission products | |
Energy of β− particles | 5.2 |
Energy of anti-neutrinos | 6.9 |
Energy of delayed γ-rays | 5.0 |
Sum (excluding escaping anti-neutrinos) | 191.0 |
Energy released when those prompt neutrons which don't (re)produce fission are captured | 9.1 |
Energy converted into heat in an operating thermal nuclear reactor | 200.1 |
Weapon material
As a potential weapon material, pure uranium-233 is more similar to plutonium-239 than uranium-235 in terms of source (bred vs natural), half-life and critical mass (both 4–5 kg in beryllium-reflected sphere).[7] Unlike reactor-bred plutonium, it has a very low spontaneous fission rate, which combined with its low critical mass made it initially attractive for compact gun-type weapons, such as small-diameter artillery shells.[8]
A declassified 1966 memo from the US nuclear program stated that uranium-233 has been shown to be highly satisfactory as a weapons material, though it was only superior to plutonium in rare circumstances. It was claimed that if the existing weapons were based on uranium-233 instead of plutonium-239, Livermore would not be interested in switching to plutonium.[9]
The co-presence of uranium-232[10] can complicate the manufacture and use of uranium-233, though the Livermore memo indicates a likelihood that this complication can be worked around.[9]
While it is thus possible to use uranium-233 as the fissile material of a nuclear weapon, speculation[11] aside, there is scant publicly available information on this isotope actually having been weaponized:
- The United States detonated an experimental device in the 1955
- The
- In 1998, as part of its Pokhran-II tests, India detonated an experimental 233U device of low-yield (0.2 kt) called Shakti V.[15][16]
The
Overall the United States is thought to have produced two tons of 233U, of various levels of purity, some with 232U impurity content as low as 6 ppm.[21]
232U impurity
Production of 233U (through the irradiation of
- 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
- 230Th (n,γ) → 231Th (β−) → 231Pa (n,γ) → 232Pa (β−) → 232U
The
- 232U (α, 68.9 y)
- 228Th (α, 1.9 y)
- 224Ra (α, 5.44 MeV, 3.6 d, with a γ of 0.24 MeV)
- 220Rn (α, 6.29 MeV, 56 s, with a γ of 0.54 MeV)
- 216Po (α, 0.15 s)
- 212Pb (β−, 10.64 h)
- 212Bi (α, 61 min, 0.78 MeV)
- 208Tl (β−, 1.8 MeV, 3 min, with a γ of 2.6 MeV)
- 208Pb (stable)
This makes manual handling in a
The hazards are significant even at 5
The production of "clean" 233U, low in 232U, requires a few factors: 1) obtaining a relatively pure 232Th source, low in 230Th (which also transmutes to 232U), 2) moderating the incident neutrons to have an energy not higher that 6 MeV (too-high energy neutrons cause the 232Th (n,2n) → 231Th reaction) and 3) removing the thorium sample from neutron flux before the 233U concentration builds up to a too high level, in order to avoid fissioning the 233U itself (which would produce energetic neutrons).[21][23]
The
Further information
Thorium, from which 233U is bred, is roughly three to four times more abundant in the Earth's crust than uranium.[25][26] The decay chain of 233U itself is part of the
Uses for uranium-233 include the production of the medical isotopes
The
See also
Notes
- ^ "Uranium-233 at the Hanford Nuclear Site" (PDF). Washington State Department of Health, Division of Environmental Health, Office of Radiation Protection. December 2002.
- ^ a b c C. W. Forsburg; L. C. Lewis (24 September 1999). "Uses For Uranium-233: What Should Be Kept for Future Needs?" (PDF). Ornl-6952. Oak Ridge National Laboratory.
- Pittsburgh Press. United Press. 29 September 1946. Retrieved 18 October 2011.
- ^ "Third Nuclear Source Bared". The Tuscaloosa News. United Press. 21 October 1946. Retrieved 18 October 2011.
- .
- ^ "Nuclear fission 4.7.1". kayelaby.npl.co.uk. Retrieved 21 April 2018.
- ^ Nuclear proliferation factbook. Committee on Governmental Affairs. Subcommittee on Energy, N. Proliferation., United States. Congress. House. Committee on Foreign Affairs. Subcommittee on International Economic Policy and Trade., United States. Congress. House. Committee on Foreign Affairs. Subcommittee on Arms Control, I. Security. 1985. p. 295. Retrieved 29 November 2019.
- ^ Hansen, Chuck (2007). Swords of Armageddon: US Nuclear Weapons Development since 1945, Version 2. Chuckelea Publications. pp. I-262, I-270.
- ^ OSTI 79078.
- ^ ISBN 0471465607. "The US tested a few uranium-233 bombs, but the presence of uranium-232 in the uranium-233 was a problem; the uranium-232 is a copious alpha emitter and tended to 'poison' the uranium-233 bomb by knocking stray neutrons from impurities in the bomb material, leading to possible pre-detonation. Separation of the uranium-232 from the uranium-233 proved to be very difficult and not practical. The uranium-233 bomb was never deployed since plutonium-239 was becoming plentiful."
- ISBN 978-3-527-32610-5. Retrieved 19 March 2012. states briefly that U233 is "thought to be a component of India's weapon programbecause of the availability of Thorium in abundance in India", and could be elsewhere as well.
- ^ "Operation Teapot". Nuclear Weapon Archive. 15 October 1997. Retrieved 9 December 2008.
- ^ "Operation Buster-Jangle". Nuclear Weapon Archive. 15 October 1997. Retrieved 18 March 2012.
- International Security4:3 (1979–80) 192–197.
- ^ Rajat Pandit (28 August 2009). "Forces gung-ho on N-arsenal". The Times of India. Retrieved 20 July 2012.
- ^ "India's Nuclear Weapons Program – Operation Shakti: 1998". 30 March 2001. Retrieved 21 July 2012.
- ^ "Historical use of thorium at Hanford" (PDF). hanfordchallenge.org. Archived from the original (PDF) on 12 May 2013. Retrieved 21 April 2018.
- ^ "Chronology of Important FOIA Documents: Hanford's Semi-Secret Thorium to U-233 Production Campaign" (PDF). hanfordchallenge.org. Archived from the original (PDF) on 15 October 2012. Retrieved 21 April 2018.
- ^ "Questions and Answers on Uranium-233 at Hanford" (PDF). radioactivist.org. Retrieved 21 April 2018.
- ^ "Hanford Radioactivity in Salmon Spawning Grounds" (PDF). clarku.edu. Retrieved 21 April 2018.
- ^ a b Robert Alvarez. "Managing the Uranium-233 Stockpile of the United States" (PDF). Science and Global Security.
- ^ Nuclear Materials FAQ
- ^ US patent 4393510
- ^ SA LFTR Energy (Pty.) Ltd. "The Superior Design Advantages over All Other Nuclear Reactor Designs of the Liquid Fluoride Thorium Reactor (LFTR), with an Emphasis on Its Anti-Proliferation Features" (PDF). The South Africa Independent LFTR Power Producer Project. p. 10.
- ^ "Abundance in Earth's Crust: periodicity". WebElements.com. Archived from the original on 23 May 2008. Retrieved 12 April 2014.
- ^ "It's Elemental — The Periodic Table of Elements". Jefferson Lab. Archived from the original on 29 April 2007. Retrieved 14 April 2007.