Thorium fuel cycle

Short description: Nuclear fuel cycle

A sample of thorium

The thorium fuel cycle is a nuclear fuel cycle that uses an isotope of thorium, The element Chemistry:Thorium does not exist., as the fertile material. In the reactor, The element Chemistry:Thorium does not exist. is transmuted into the fissile artificial uranium isotope The element Chemistry:Uranium does not exist. which is the nuclear fuel. Unlike natural uranium, natural thorium contains only trace amounts of fissile material (such as The element Chemistry:Thorium does not exist.), which are insufficient to initiate a nuclear chain reaction. Additional fissile material or another neutron source is necessary to initiate the fuel cycle. In a thorium-fuelled reactor, The element Chemistry:Thorium does not exist. absorbs neutrons to produce The element Chemistry:Uranium does not exist.. This parallels the process in uranium breeder reactors whereby fertile The element Chemistry:Uranium does not exist. absorbs neutrons to form fissile The element Chemistry:Plutonium does not exist.. Depending on the design of the reactor and fuel cycle, the generated The element Chemistry:Uranium does not exist. either fissions in situ or is chemically separated from the used nuclear fuel and formed into new nuclear fuel.

The thorium fuel cycle has several potential advantages over a uranium fuel cycle, including thorium's greater abundance, superior physical and nuclear properties, reduced plutonium and actinide production,[1] and better resistance to nuclear weapons proliferation when used in a traditional light water reactor[1][2] though not in a molten salt reactor.[3][4][5]

## Contents

* 1 History
* 2 Nuclear reactions with thorium
* 2.1 Fission product waste
* 2.2 Actinide waste
* 2.3 Uranium-232 contamination
* 3 Nuclear fuel
* 3.1 Advantages
* 3.2 Disadvantages
* 4 Thorium-fueled reactors
* 4.1 List of thorium-fueled reactors
* 5 See also
* 6 References
* 7 Further reading
* 8 External links

## History

See also: Physics:Thorium-based nuclear power

Concerns about the limits of worldwide uranium resources motivated initial interest in the thorium fuel cycle.[6] It was envisioned that as uranium reserves were depleted, thorium would supplement uranium as a fertile material. However, for most countries uranium was relatively abundant and research in thorium fuel cycles waned. A notable exception was India's three-stage nuclear power programme.[7] In the twenty-first century thorium's claimed potential for improving proliferation resistance and waste characteristics led to renewed interest in the thorium fuel cycle.[8][9][10] While thorium is more abundant in the continental crust than uranium and easily extracted from monazite as a side product of rare earth element mining, it is much less abundant in seawater than uranium.[11]

At Oak Ridge National Laboratory in the 1960s, the Molten-Salt Reactor Experiment used The element Chemistry:Uranium does not exist. as the fissile fuel in an experiment to demonstrate a part of the Molten Salt Breeder Reactor that was designed to operate on the thorium fuel cycle. Molten salt reactor (MSR) experiments assessed thorium's feasibility, using thorium(IV) fluoride dissolved in a molten salt fluid that eliminated the need to fabricate fuel elements. The MSR program was defunded in 1976 after its patron Alvin Weinberg was fired.[12]

In 1993, Carlo Rubbia proposed the concept of an energy amplifier or "accelerator driven system" (ADS), which he saw as a novel and safe way to produce nuclear energy that exploited existing accelerator technologies. Rubbia's proposal offered the potential to incinerate high-activity nuclear waste and produce energy from natural thorium and depleted uranium.[13][14]

Kirk Sorensen, former NASA scientist and Chief Technologist at Flibe Energy, has been a long-time promoter of thorium fuel cycle and particularly liquid fluoride thorium reactors (LFTRs). He first researched thorium reactors while working at NASA, while evaluating power plant designs suitable for lunar colonies. In 2006 Sorensen started "energyfromthorium.com" to promote and make information available about this technology.[15]

A 2011 MIT study concluded that although there is little in the way of barriers to a thorium fuel cycle, with current or near term light-water reactor designs there is also little incentive for any significant market penetration to occur. As such they conclude there is little chance of thorium cycles replacing conventional uranium cycles in the current nuclear power market, despite the potential benefits.[16]

## Nuclear reactions with thorium

In the thorium cycle, fuel is formed when The element Chemistry:Thorium does not exist. captures a neutron (whether in a fast reactor or thermal reactor) to become The element Chemistry:Thorium does not exist.. This normally emits an electron and an anti-neutrino (ν) by β− decay to become The element Chemistry:Protactinium does not exist.. This then emits another electron and anti-neutrino by a second β− decay to become The element Chemistry:Uranium does not exist., the fuel:

nneutron+23290Th⟶23390Th→βA−23391Pa→βA−A92233A2922233Ufuel

### Fission product waste

Nuclear fission produces radioactive fission products which can have half-lives from days to greater than 200,000 years. According to some toxicity studies,[17] the thorium cycle can fully recycle actinide wastes and only emit fission product wastes, and after a few hundred years, the waste from a thorium reactor can be less toxic than the uranium ore that would have been used to produce low enriched uranium fuel for a light water reactor of the same power. Other studies assume some actinide losses and find that actinide wastes dominate thorium cycle waste radioactivity at some future periods.[18] Some fission products have been proposed for nuclear transmutation, which would further reduce the amount of nuclear waste and the duration during which it would have to be stored (whether in a deep geological repository or elsewhere). However, while the principal feasibility of some of those reactions has been demonstrated at laboratory scale, there is, as of 2024, no large scale deliberate transmutation of fission products anywhere in the world, and the upcoming MYRRHA research project into transmutation is mostly focused on transuranic waste. Furthermore, the cross section of some fission products is relatively low and others - such as caesium - are present as a mixture of stable, short lived and long lived isotopes in nuclear waste, making transmutation dependent on expensive isotope separation.

### Actinide waste

In a reactor, when a neutron hits a fissile atom (such as certain isotopes of uranium), it either splits the nucleus or is captured and transmutes the atom. In the case of The element Chemistry:Uranium does not exist., the transmutations tend to produce useful nuclear fuels rather than transuranic waste. When The element Chemistry:Uranium does not exist. absorbs a neutron, it either fissions or becomes The element Chemistry:Uranium does not exist.. The chance of fissioning on absorption of a thermal neutron is about 92%; the capture-to-fission ratio of The element Chemistry:Uranium does not exist., therefore, is about 1:12 – which is better than the corresponding capture vs. fission ratios of The element Chemistry:Uranium does not exist. (about 1:6), or The element Chemistry:Plutonium does not exist. or The element Chemistry:Plutonium does not exist. (both about 1:3).[6][19] The result is less transuranic waste than in a reactor using the uranium-plutonium fuel cycle.

Transmutations in the thorium fuel cycle | 237Np

|

| ↑
|  | 231U | ←  | 232U  | ↔  | 233U  | ↔  | 234U  | ↔  | 235U | ↔  | 236U  | →  | 237U
|  | ↓ |  | ↑ |  | ↑ |  | ↑
|  | 231Pa  | →  | 232Pa | ←  | 233Pa | →  | 234Pa
|  | ↑ |  |  |  | ↑ |
230Th  | →  | 231Th | ←  | 232Th | →  | 233Th
(Nuclides before a yellow background in italic have half-lives under 30 days;
nuclides in bold have half-lives over 1,000,000 years;
nuclides in red frames are fissile)

The element Chemistry:Uranium does not exist., like most actinides with an even number of neutrons, is not fissile, but neutron capture produces fissile The element Chemistry:Uranium does not exist.. If the fissile isotope fails to fission on neutron capture, it produces The element Chemistry:Uranium does not exist., The element Chemistry:Neptunium does not exist., The element Chemistry:Plutonium does not exist., and eventually fissile The element Chemistry:Plutonium does not exist. and heavier isotopes of plutonium. The The element Chemistry:Neptunium does not exist. can be removed and stored as waste or retained and transmuted to plutonium, where more of it fissions, while the remainder becomes The element Chemistry:Plutonium does not exist., then americium and curium, which in turn can be removed as waste or returned to reactors for further transmutation and fission.

However, the The element Chemistry:Protactinium does not exist. (with a half-life of 3.27×104 years) formed via (n,2n) reactions with The element Chemistry:Thorium does not exist. (yielding The element Chemistry:Thorium does not exist. that decays to The element Chemistry:Protactinium does not exist.), while not a transuranic waste, is a major contributor to the long-term radiotoxicity of spent nuclear fuel. While 231Pa can in principle be converted back to 232Th by neutron absorption, its neutron absorption cross section is relatively low, making this rather difficult and possibly uneconomic.

### Uranium-232 contamination

The element Chemistry:Uranium does not exist. is also formed in this process, via (n,2n) reactions between fast neutrons and The element Chemistry:Uranium does not exist., The element Chemistry:Protactinium does not exist., and The element Chemistry:Thorium does not exist.:

23290Th→+n23390Th→βA−23391Pa →βA−23392U→+n-2n23292U23290Th→+n23390Th→βA−23391Pa →+n-2n23291Pa→βA−23292U23290Th→+n-2n23190Th→βA−23191Pa →+n23291Pa→βA−23292U

Unlike most even numbered heavy isotopes, The element Chemistry:Uranium does not exist. is also a fissile fuel fissioning just over half the time when it absorbs a thermal neutron.[20] The element Chemistry:Uranium does not exist. has a relatively short half-life (68.9 years), and some decay products emit high energy gamma radiation, such as The element Chemistry:Radon does not exist., The element Chemistry:Bismuth does not exist. and particularly The element Chemistry:Thallium does not exist.. The full decay chain, along with half-lives and relevant gamma energies, is:

The 4n decay chain of 232Th, commonly called the "thorium series"

The element Chemistry:Uranium does not exist. decays to The element Chemistry:Thorium does not exist. where it joins the [[thorium series|decay chain of The element Chemistry:Thorium does not exist.]]

A92232A2922232U→αA90228A2902228Th (68.9 years)A90228A2902228Th→αA88224A2882224Ra (1.9 year)A88224A2882224Ra→αA86220A2862220Rn (3.6 day, 0.24 MeV)A86220A2862220Rn→αA84216A2842216Po (55 s, 0.54 MeV)A84216A2842216Po→αA82212A2822212Pb (0.15 s)A82212A2822212Pb→βA−A83212A2832212Bi (10.64 h)A83212A2832212Bi→αA81208A2812208Tl (61 m, 0.78 MeV)A81208A2812208Tl→βA−A82208A2822208Pb (3 m, 2.6 MeV)

Thorium-cycle fuels produce hard gamma emissions, which damage electronics, limiting their use in bombs. The element Chemistry:Uranium does not exist. cannot be chemically separated from The element Chemistry:Uranium does not exist. from used nuclear fuel; however, chemical separation of thorium from uranium removes the decay product The element Chemistry:Thorium does not exist. and the radiation from the rest of the decay chain, which gradually build up as The element Chemistry:Thorium does not exist. reaccumulates. The contamination could also be avoided by using a molten-salt breeder reactor and separating the The element Chemistry:Protactinium does not exist. before it decays into The element Chemistry:Uranium does not exist..[3] The hard gamma emissions also create a radiological hazard which requires remote handling during reprocessing.

## Nuclear fuel

As a fertile material thorium is similar to The element Chemistry:Uranium does not exist., the major part of natural and depleted uranium. The thermal neutron absorption cross section (σa) and resonance integral (average of neutron cross sections over intermediate neutron energies) for The element Chemistry:Thorium does not exist. are about three and one third times those of the respective values for The element Chemistry:Uranium does not exist..

### Advantages

The primary physical advantage of thorium fuel is that it uniquely makes possible a breeder reactor that runs with slow neutrons, otherwise known as a thermal breeder reactor.[6] These reactors are often considered simpler than the more traditional fast-neutron breeders. Although the thermal neutron fission cross section (σf) of the resulting The element Chemistry:Uranium does not exist. is comparable to The element Chemistry:Uranium does not exist. and The element Chemistry:Plutonium does not exist., it has a much lower capture cross section (σγ) than the latter two fissile isotopes, providing fewer non-fissile neutron absorptions and improved neutron economy. The ratio of neutrons released per neutron absorbed (η) in The element Chemistry:Uranium does not exist. is greater than two over a wide range of energies, including the thermal spectrum. A breeding reactor in the uranium–plutonium cycle needs to use fast neutrons, because in the thermal spectrum one neutron absorbed by The element Chemistry:Plutonium does not exist. on average leads to less than two neutrons.

Thorium is estimated to be about three to four times more abundant than uranium in Earth's crust,[21] although present knowledge of reserves is limited. Current demand for thorium has been satisfied as a by-product of rare-earth extraction from monazite sands. Notably, there is very little thorium dissolved in seawater, so seawater extraction is not viable, as it is with uranium. Using breeder reactors, known thorium and uranium resources can both generate world-scale energy for thousands of years.

Thorium-based fuels also display favorable physical and chemical properties that improve reactor and repository performance. Compared to the predominant reactor fuel, uranium dioxide (UO2), thorium dioxide (ThO2) has a higher melting point, higher thermal conductivity, and lower coefficient of thermal expansion. Thorium dioxide also exhibits greater chemical stability and, unlike uranium dioxide, does not further oxidize.[6]

Because the The element Chemistry:Uranium does not exist. produced in thorium fuels is significantly contaminated with The element Chemistry:Uranium does not exist. in proposed power reactor designs, thorium-based used nuclear fuel possesses inherent proliferation resistance. The element Chemistry:Uranium does not exist. cannot be chemically separated from The element Chemistry:Uranium does not exist. and has several decay products that emit high-energy gamma radiation. These high-energy photons are a radiological hazard that necessitate the use of remote handling of separated uranium and aid in the passive detection of such materials.

The long-term (on the order of roughly 103 to 106 years) radiological hazard of conventional uranium-based used nuclear fuel is dominated by plutonium and other minor actinides, after which long-lived fission products become significant contributors again. A single neutron capture in The element Chemistry:Uranium does not exist. is sufficient to produce transuranic elements, whereas five captures are generally necessary to do so from The element Chemistry:Thorium does not exist.. 98–99% of thorium-cycle fuel nuclei would fission at either The element Chemistry:Uranium does not exist. or The element Chemistry:Uranium does not exist., so fewer long-lived transuranics are produced. Because of this, thorium is a potentially attractive alternative to uranium in mixed oxide (MOX) fuels to minimize the generation of transuranics and maximize the destruction of plutonium.[22]

### Disadvantages

There are several challenges to the application of thorium as a nuclear fuel, particularly for solid fuel reactors:

In contrast to uranium, naturally occurring thorium is effectively mononuclidic and contains no fissile isotopes; fissile material, generally The element Chemistry:Uranium does not exist., The element Chemistry:Uranium does not exist. or plutonium, must be added to achieve criticality. This, along with the high sintering temperature necessary to make thorium-dioxide fuel, complicates fuel fabrication. Oak Ridge National Laboratory experimented with thorium tetrafluoride as fuel in a molten salt reactor from 1964 to 1969, which was expected to be easier to process and separate from contaminants that slow or stop the chain reaction.

In an open fuel cycle (i.e. using The element Chemistry:Uranium does not exist. in situ), higher burnup is necessary to achieve a favorable neutron economy. Although thorium dioxide performed well at burnups of 170,000 MWd/t and 150,000 MWd/t at Fort St. Vrain Generating Station and AVR respectively,[6] challenges complicate achieving this in light water reactors (LWR), which compose the vast majority of existing power reactors.

In a once-through thorium fuel cycle, thorium-based fuels produce far less long-lived transuranics than uranium-based fuels, but some long-lived actinide products still constitute a long-term radiological impact, especially The element Chemistry:Protactinium does not exist. and The element Chemistry:U does not exist..[17] In a closed cycle,The element Chemistry:U does not exist. and The element Chemistry:Protactinium does not exist. can be reprocessed. The element Chemistry:Protactinium does not exist. is also considered an excellent burnable poison absorber in light water reactors.[23]

Another challenge associated with the thorium fuel cycle is the comparatively long interval over which The element Chemistry:Thorium does not exist. breeds to The element Chemistry:Uranium does not exist.. The half-life of The element Chemistry:Protactinium does not exist. is about 27 days, which is an order of magnitude longer than the half-life of The element Chemistry:Neptunium does not exist.. As a result, substantial The element Chemistry:Protactinium does not exist. develops in thorium-based fuels. The element Chemistry:Protactinium does not exist. is a significant neutron absorber and, although it eventually breeds into fissile The element Chemistry:Uranium does not exist., this requires two more neutron absorptions, which degrades neutron economy and increases the likelihood of transuranic production.

Alternatively, if solid thorium is used in a closed fuel cycle in which The element Chemistry:Uranium does not exist. is recycled, remote handling is necessary for fuel fabrication because of the high radiation levels resulting from the decay products of The element Chemistry:Uranium does not exist.. This is also true of recycled thorium because of the presence of The element Chemistry:Thorium does not exist., which is part of the The element Chemistry:Uranium does not exist. decay sequence. Further, unlike proven uranium fuel recycling technology (e.g. PUREX), recycling technology for thorium (e.g. THOREX) is only under development.

Although the presence of The element Chemistry:Uranium does not exist. complicates matters, there are public documents showing that The element Chemistry:Uranium does not exist. has been used once in a nuclear weapon test. The United States tested a composite The element Chemistry:Uranium does not exist.-plutonium bomb core in the MET (Military Effects Test) blast during Operation Teapot in 1955, though with much lower yield than expected.[24]

Advocates for liquid core and molten salt reactors such as LFTRs claim that these technologies negate thorium's disadvantages present in solid fuelled reactors. As only two liquid-core fluoride salt reactors have been built (the ORNL ARE and MSRE) and neither have used thorium, it is hard to validate the exact benefits.[6]

## Thorium-fueled reactors

Thorium fuels have fueled several different reactor types, including light water reactors, heavy water reactors, high temperature gas reactors, sodium-cooled fast reactors, and molten salt reactors.[25]

### List of thorium-fueled reactors

It has been suggested that this section be split out into another page titled List of thorium-fueled reactors. (Discuss) (August 2020)

|

| This physics needs to be updated. Please update this physics to reflect recent events or newly available information. (August 2020)

|

From IAEA TECDOC-1450 "Thorium Fuel Cycle – Potential Benefits and Challenges", Table 1: Thorium utilization in different experimental and power reactors.[6] Additionally from Energy Information Administration, "Spent Nuclear Fuel Discharges from U. S. Reactors", Table B4: Dresden 1 Assembly Class.[26]

Name | Operation period | Country | Reactor type | Power | Fuel

|
|
|
|
|

NRX & NRU | 1947 (NRX) + 1957 (NRU); Irradiation–testing of few fuel elements |  Canada | MTR (pin assemblies) | 020000 20 MW; 200 MW (see) | Th+The element Chemistry:Uranium does not exist., Test Fuel
Dresden Unit 1 | 1960–1978 |  United States | BWR | 300000 197 MW(e) | ThO2 corner rods, UO2 clad in Zircaloy-2 tube
CIRUS; DHRUVA; & KAMINI | 1960–2010 (CIRUS); others in operation |  India | MTR thermal | 040000 40 MWt; 100 MWt; 30 kWt (low power, research) | Al+The element Chemistry:Uranium does not exist. Driver fuel, ‘J’ rod of Th & ThO2, ‘J’ rod of ThO2
Indian Point Unit 1 | 1962–1965[27] |  United States | LWBR, PWR, (pin assemblies) | 285000 285 MW(e) | Th+The element Chemistry:Uranium does not exist. Driver fuel, oxide pellets
BORAX-IV & Elk River Station | 1963–1968 |  United States | BWR (pin assemblies) | 002400 2.4 MW(e); 24 MW(e) | Th+The element Chemistry:Uranium does not exist. Driver fuel oxide pellets
MSRE ORNL | 1964–1969 |  United States | MSR | 007500 7.5 MWt | The element Chemistry:Uranium does not exist. molten fluorides
Peach Bottom Unit 1 | 1966–1972 |  United States | HTGR, Experimental (prismatic block) | 040000 40 MW(e) | Th+The element Chemistry:Uranium does not exist. Driver fuel, coated fuel particles, oxide & dicarbides
Dragon (OECD-Euratom) | 1966–1973 |  UK (also  Sweden,  Norway and  Switzerland) | HTGR, Experimental (pin-in-block design) | 020000 20 MWt | Th+The element Chemistry:Uranium does not exist. Driver fuel, coated fuel particles, oxide & dicarbides
AVR | 1967–1988 |  Germany (West) | HTGR, experimental (pebble bed reactor) | 015000 15 MW(e) | Th+The element Chemistry:Uranium does not exist. Driver fuel, coated fuel particles, oxide & dicarbides
Lingen | 1968–1973 |  Germany (West) | BWR irradiation-testing | 060000 60 MW(e) | Test fuel (Th,Pu)O2 pellets
SUSPOP/KSTR KEMA | 1974–1977 |  Netherlands | Aqueous homogeneous suspension (pin assemblies) | 001000 1 MWt | Th+HEU, oxide pellets
Fort St Vrain | 1976–1989 |  United States | HTGR, Power (prismatic block) | 330000 330 MW(e) | Th+The element Chemistry:Uranium does not exist. Driver fuel, coated fuel particles, Dicarbide
Shippingport | 1977–1982 |  United States | LWBR, PWR, (pin assemblies) | 100000 100 MW(e) | Th+The element Chemistry:Uranium does not exist. Driver fuel, oxide pellets
KAPS 1 &2; KGS 1 & 2; RAPS 2, 3 & 4 | 1980 (RAPS 2) +; continuing in all new PHWRs |  India | PHWR, (pin assemblies) | 220000 220 MW(e) | ThO2 pellets (for neutron flux flattening of initial core after start-up)
FBTR | 1985; in operation |  India | LMFBR, (pin assemblies) | 040000 40 MWt | ThO2 blanket
THTR-300 | 1985–1989 |  Germany (West) | HTGR, power (pebble type) | 300000 300 MW(e) | Th+The element Chemistry:Uranium does not exist. Driver fuel, coated fuel particles, oxide & dicarbides
TMSR-LF1 | 2023; in operation[28] |  China | Liquid fuel thorium-based molten salt experimental reactor | 002000 2 MWt | Thorium-based molten salt
Petten | 2024; planned |  Netherlands | High Flux Reactor thorium molten salt experiment | 060000 45 MW(e) | ?
SINAP | 2030; planned[29] |  China | thorium-based molten-salt reactor | 060000 10 MWt | Thorium-based molten salt

## See also

* Thorium
* Thorium-232
* Occurrence of thorium
* Thorium-based nuclear power
* List of countries by thorium resources
* List of countries by uranium reserves
* Advanced heavy-water reactor
* Alvin Radkowsky
* CANDU reactor
* Fuji MSR
* Peak uranium
* Radioactive waste
* Thorium Energy Alliance
* Weinberg Foundation
* World energy resources and consumption

## References

1. ↑ 1.0 1.1 Robert Hargraves; Ralph Moir (January 2011). "Liquid Fuel Nuclear Reactors". American Physical Society Forum on Physics & Society. http://www.aps.org/units/fps/newsletters/201101/hargraves.cfm.
2. ↑ Sublette, Carey (20 February 1999). "Nuclear Materials FAQ". http://nuclearweaponarchive.org/Nwfaq/Nfaq6.html.
3. ↑ 3.0 3.1 Kang, J.; Von Hippel, F. N. (2001). "U-232 and the proliferation-resistance of U-233 in spent fuel". Science & Global Security 9 (1): 1–32. doi:10.1080/08929880108426485. Bibcode: 2001S&GS....9....1K. "Archived copy". http://www.torium.se/res/Documents/9_1kang.pdf.
4. ↑ ""Superfuel" Thorium a Proliferation Risk?". 5 December 2012. http://www.popularmechanics.com/science/energy/nuclear/is-the-superfuel-thorium-riskier-than-we-thought-14821644.
5. ↑ Ashley, Stephen; Parks, Geoffrey (2012-12-05). "Thorium fuel has risks". Nature 492 (7427): 31–33. doi:10.1038/492031a. PMID 23222590. "We are concerned, however, that other processes, which might be conducted in smaller facilities, could be used to convert 232Th into 233U while minimizing contamination by 232U, thus posing a proliferation threat. Notably, the chemical separation of an intermediate isotope — protactinium-233 — that decays into 233U is a cause for concern. ... The International Atomic Energy Agency (IAEA) considers 8 kilograms of 233U to be enough to construct a nuclear weapon1. Thus, 233U poses proliferation risks.".
6. ↑ 6.0 6.1 6.2 6.3 6.4 6.5 6.6 "IAEA-TECDOC-1450 Thorium Fuel Cycle – Potential Benefits and Challenges". International Atomic Energy Agency. May 2005. http://www-pub.iaea.org/MTCD/publications/PDF/TE_1450_web.pdf.
7. ↑ Ganesan Venkataraman (1994). Bhabha and his magnificent obsessions. Universities Press. p. 157.
8. ↑ "IAEA-TECDOC-1349 Potential of thorium-based fuel cycles to constrain plutonium and to reduce the long-lived waste toxicity". International Atomic Energy Agency. 2002. http://www-pub.iaea.org/MTCD/publications/PDF/te_1349_web.pdf.
9. ↑ Evans, Brett (April 14, 2006). "Scientist urges switch to thorium". ABC News. http://www.abc.net.au/news/newsitems/200604/s1616391.htm.
10. ↑ Martin, Richard (December 21, 2009). "Uranium Is So Last Century – Enter Thorium, the New Green Nuke". Wired. https://www.wired.com/magazine/2009/12/ff_new_nukes/. Retrieved 2010-06-19.
11. ↑ Moore, Willard S. (1981-05-01). "The thorium isotope content of ocean water" (in en). Earth and Planetary Science Letters 53 (3): 419–426. doi:10.1016/0012-821X(81)90046-7. ISSN 0012-821X. Bibcode: 1981E&PSL..53..419M. https://dx.doi.org/10.1016/0012-821X(81)90046-7.
12. ↑ Miller, Daniel (March 2011). "Nuclear community snubbed reactor safety message: expert". ABC News. http://www.abc.net.au/news/2011-03-18/nuclear-community-snubbed-reactor-safety-message/2649768.
13. ↑ Dean, Tim (April 2006). "New age nuclear". Cosmos. http://www.cosmosmagazine.com/features/print/348/new-age-nuclear?page=0,3.
14. ↑ MacKay, David J. C. (February 20, 2009). Sustainable Energy – without the hot air. UIT Cambridge Ltd.. p. 166. http://www.inference.phy.cam.ac.uk/withouthotair/c24/page_166.shtml. Retrieved 2010-06-19.
15. ↑ "Flibe Energy". Flibe Energy. http://flibe-energy.com/.
16. ↑ ﻿The Future of the Nuclear Fuel Cycle﻿ (Report). MIT. 2011. p. 181. https://energy.mit.edu/wp-content/uploads/2011/04/MITEI-The-Future-of-the-Nuclear-Fuel-Cycle.pdf.
17. ↑ 17.0 17.1 Le Brun, C.; L. Mathieu. "Impact of the MSBR concept technology on long-lived radio-toxicity and proliferation resistance". Technical Meeting on Fissile Material Management Strategies for Sustainable Nuclear Energy, Vienna 2005. http://hal.archives-ouvertes.fr/docs/00/04/14/97/PDF/document_IAEA.pdf.
18. ↑ "Nuclear Energy With (Almost) No Radioactive Waste?". Laboratoire de Physique Subatomique et de Cosmologie (LPSC). July 2001. http://lpsc.in2p3.fr/gpr/english/NEWNRW/NEWNRW.html#foot284. "according to computer simulations done at ISN, this Protactinium dominates the residual toxicity of losses at 10000 years"
19. ↑ "Interactive Chart of Nuclides". http://www.nndc.bnl.gov/chart/. "Thermal neutron cross sections in barns (isotope, capture:fission, f/f+c, f/c) 233U 45.26:531.3 92.15% 11.74; 235U 98.69:585.0 85.57% 5.928; 239Pu 270.7:747.9 73.42% 2.763; 241Pu 363.0:1012 73.60% 2.788."
20. ↑ "9219.endfb7.1". http://atom.kaeri.re.kr/nuchart/getEvaf.jsp?mat=9219&lib=endfb7.1.
21. ↑ "The Use of Thorium as Nuclear Fuel". American Nuclear Society. November 2006. http://www.ans.org/pi/ps/docs/ps78.pdf.
22. ↑ "Thorium test begins". World Nuclear News. 21 June 2013. http://www.world-nuclear-news.org/ENF_Thorium_test_begins_2106131.html.
23. ↑ Kulikov, G.G.; Kulikov, E.G.; Shmelev, A.N.; Apse, V.A. (2017). "Protactinium-231 – New burnable neutron absorber". Nuclear Energy and Technology 3 (4): 255–259. doi:10.1016/j.nucet.2017.10.002.
24. ↑ "Operation Teapot". 11 November 2017. http://nuclearweaponarchive.org/Usa/Tests/Teapot.html.
25. ↑ "IAEA-TECDOC-1319 Thorium Fuel Utilization: Options and trends". International Atomic Energy Agency. November 2002. http://www.iaea.org/inisnkm/nkm/aws/fnss/fulltext/te_1319_f.pdf.
26. ↑ Spent Nuclear Fuel Discharges from U. S. Reactors. Energy Information Administration. 1995. p. 111. ISBN 978-0-7881-2070-1. https://books.google.com/books?id=uwJr2SAEdqUC&pg=PA111. Retrieved 11 June 2012. They were manufactured by General Electric (assembly code XDR07G) and later sent to the Savannah River Site for reprocessing.
27. ↑ "Indian Readied for New Uranium". Mount Vernon Argus (White Plains, New York): p. 17. March 16, 1966. https://www.newspapers.com/clip/121388402/indian-readied-for-new-uranium/.
28. ↑ Krepel, Jiri (22 January 2025). "Overview and Update of MSR Activities within GIF". https://www.gen-4.org/resources/webinars/education-and-training-series-97-overview-and-update-msr-activities-within-gif. "At 11:08 on October 11, 2023, TMSR-LF1 achieved first criticality. At 12:10 on June 17, 2024, 2MWt full power operation was achieved. On October 8, 2024, TMSR-LF1 operated at full power for 10 days with thorium fuel, and Pa-233 was detected"
29. ↑ "Why China is building a thorium molten-salt reactor". https://spectrum.ieee.org/chinas-thorium-molten-salt-reactor.

## Further reading

* Kasten, P. R. (1998). "Review of the Radkowsky Thorium reactor concept" Science & Global Security, 7(3), 237–269.
* Duncan Clark (9 September 2011), "Thorium advocates launch pressure group. Huge optimism for thorium nuclear energy at the launch of the Weinberg Foundation", The Guardian
* Nelson, A. T. (2012). "Thorium: Not a near-term commercial nuclear fuel". Bulletin of the Atomic Scientists 68 (5): 33–44. doi:10.1177/0096340212459125. Bibcode: 2012BuAtS..68e..33N. https://zenodo.org/record/1235552.
* B.D. Kuz'minov, V.N. Manokhin, (1998) "Status of nuclear data for the thorium fuel cycle", IAEA translation from the Russian journal Yadernye Konstanty (Nuclear Constants) Issue No. 3–4, 1997
* Thorium and uranium fuel cycles comparison by the UK National Nuclear Laboratory
* Fact sheet on thorium at the World Nuclear Association.
* Annotated bibliography for the thorium fuel cycle from the Alsos Digital Library for Nuclear Issues

## External links

* Template:Wikidata-inline
* International Thorium Energy Committee

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