The Nuclear Fuel Cycle

Why anyone would choose a harder fuel, and who is choosing it

Primer • Foundations • Status as of 20 October 2026

Abstract

Thorium cannot start a reactor on its own, its recycled fuel is fiercely radioactive, and its oxide is hard to dissolve. There is no commercial supply chain for any of it. So why do India, China and a handful of companies keep at it?

This article makes the case for thorium on its physics, sets each advantage against its cost, and then looks at who is pursuing it and why. The short answer is that the advantages are real, but they pay off only for a country with a particular need, or for a reactor designed to use them.

The Question

Read the list of thorium’s problems and it is fair to ask why anyone bothers. Thorium-232 is not fissile: it will not sustain a chain reaction by itself, so every thorium reactor needs a second fuel to drive it [2]. When it is irradiated it turns into uranium-233, and the uranium-233 comes with traces of a contaminant that forces all recycling to be done by remote control [3]. Compared with the uranium cycle the industry already runs, thorium looks like more work for the same electricity.

And yet it keeps coming back. The answer lies in a few pieces of physics that uranium cannot match, and in the circumstances of the countries and companies that need those pieces most. The rest of this article takes them in turn.

What Thorium Offers

It breeds with slow neutrons

The biggest advantage is the least obvious one. Thorium-232 is fertile: when it absorbs a neutron it becomes thorium-233, which decays through protactinium-233 into uranium-233, a good fissile fuel [2]. Uranium-238 does the same thing, turning into plutonium-239. The difference shows up in what the two fissile products do with slow neutrons.

To breed, a reactor has to make at least one new fissile atom for every one it burns. Each fission must therefore release enough neutrons to keep the chain going and still have one left to convert a fertile atom, after losses. Uranium-233 releases more than two neutrons for every neutron it absorbs across a wide range of slow, or thermal, neutron energies. Uranium-235 and plutonium-239 do not [3].

That is why breeding plutonium from uranium needs a fast reactor, with no moderator to slow the neutrons. The World Nuclear Association puts it plainly: breeding in a slow-neutron system is unique to thorium fuels and is not possible with uranium [2]. Thorium is the only practical route to a breeder that uses water or molten salt and graphite to slow its neutrons.

This is what the early American thorium projects were built to test. The light-water breeder and the molten salt reactor breeder were both designed to breed uranium-233 from thorium with thermal neutrons [22]. Shippingport’s light-water breeder ended its core life in 1982 with 1.39 percent more fissile fuel than it started with [2]. Oak Ridge’s Molten Salt Reactor Experiment ran on uranium-233 in its second campaign [2].

The margin is thin, though. Shippingport’s breeding ratio is reported as 1.01 [2], and the World Nuclear Association describes thermal breeding with thorium as possible but quite difficult, needing a reactor that wastes very few neutrons [2]. The physics allows it. It does not make it easy.

It makes less long-lived waste

The second advantage comes from where thorium sits on the chart of isotopes. Thorium-232 is six mass units lighter than uranium-238. A uranium-238 nucleus is one neutron capture away from plutonium-239. A thorium-232 nucleus is seven captures away, and further still from americium and curium.

Those heavy elements, plutonium and the minor actinides neptunium, americium and curium, are what keep spent uranium fuel hazardous for tens of thousands of years. The IAEA’s review of thorium fuels finds that the thorium–uranium-233 cycle forms much less plutonium and long-lived minor actinides than the uranium–plutonium cycle [3]. The World Nuclear Association agrees that production of all actinides is lower than with conventional fuel [2].

The advantage is narrower than it sounds. Fission splits uranium-233 into much the same fission products as uranium-235, at about the same energy per fission [2], so the short- and medium-lived waste is similar. The gain is in the long-lived actinides. Thorium fuel also has long-lived products of its own, such as protactinium-231 and thorium-229, which the IAEA notes may matter in the long term [3].

Its oxide is a better ceramic

The third advantage is the fuel material. Thorium dioxide, or thoria, melts at about 3,350 degrees Celsius against about 2,800 for uranium dioxide [3]. It conducts heat better and expands less as it heats [2] [3]. In the reactor it releases about a tenth as much fission gas as uranium dioxide [3].

Thoria also has only one stable oxide. Uranium dioxide oxidizes readily to U₃O₈ and UO₃; thoria does not oxidize further [3]. The IAEA concludes that this makes long-term storage and disposal of spent thoria fuel simpler [3]. A fuel that is a stable waste form when it comes out of the reactor is a real advantage.

The same stability is a cost. A material that resists oxidation also resists the acids used to dissolve it for reprocessing. That point returns below, with the other costs.

There is a lot of it

The fourth advantage is the one most often quoted. Thorium is about three to four times as abundant as uranium in the Earth’s crust [3]. Natural thorium is essentially all thorium-232, so none of it is lost to an enrichment plant’s tails [2].

This is real, but on its own it does not decide much. Uranium is not scarce, and it makes up only a small part of the cost of nuclear electricity [2]. The IAEA says thorium fuels have not been introduced commercially because uranium resources turned out to be sufficient [3]. Abundance matters most to a country that has thorium and cannot get uranium.

Proliferation cuts both ways

The fifth argument is about weapons, and it runs in two directions. Making uranium-233 also makes some uranium-232. Its decay chain includes thallium-208, which gives off a hard gamma ray [3]. That makes the material hard to handle and easy to detect, which the IAEA and the World Nuclear Association both count as proliferation resistance [2] [3].

But uranium-233 can be used in a bomb. In 1955 the United States detonated a device with a core of plutonium and uranium-233 in Operation Teapot [2]. The IAEA treats uranium-233 as direct-use material, like highly enriched uranium. Its significant quantity, the amount it treats as enough for one weapon, is 8 kilograms, against 25 kilograms of uranium-235 [2]. Thorium fuel is harder to misuse than separated plutonium. It is not immune.

Taken together, these five points are a real case. Thorium breeds where uranium cannot, leaves fewer long-lived actinides, and comes in a better ceramic. Each of them, though, comes with a price.

What It Costs

The costs line up against the benefits almost one for one. None of them is a matter of opinion.

It always needs a driver. India’s government told its parliament in 2014 that “it is not possible to build a nuclear reactor using Thorium alone” [1]. The driver has to be uranium-235 from an enrichment plant, plutonium from a reprocessing plant, or uranium-233 bred earlier [2]. A thorium program does not escape the uranium cycle. At the start, it depends on it.

The breeding takes time. Protactinium-233 has a half-life of about 27 days [2]. The IAEA says irradiated thorium fuel needs at least a year of cooling before the uranium-233 can be recovered and used [3].

Recycled fuel must be handled remotely. The same uranium-232 gamma rays that hinder diversion also make every step of recycling hard. Fuel containing recycled uranium-233 has to be reprocessed and made into new fuel behind shielding, by remote control [3]. The World Nuclear Association says this raises the cost of fuel fabrication [2]. How much uranium-232 there is depends on how the uranium-233 was made, as Table 1 shows.

TABLE 1. Uranium-232 in bred uranium-233, by source.

How the uranium-233 was bred	Uranium-232 content (parts per million)
Fast-reactor blankets	About 100 [3]
Thorium oxide in a heavy-water reactor	About 500 [3]
Thorium-plutonium fuel in a VVER, Russia’s pressurized-water design	About 3,500 [3]

The oxide is hard to reprocess. Thoria does not dissolve readily in the concentrated nitric acid that reprocessing plants use. THOREX, the thorium counterpart of PUREX, adds hydrofluoric acid to force it, and that acid corrodes stainless-steel equipment [3]. Making the fuel is harder too: thoria’s high melting point means pellets must be sintered above 2,000 degrees Celsius, or made with additives [3].

There is no commercial fuel chain. The IAEA described experience with thorium fuels as “very limited” compared with uranium and mixed-oxide fuels [3]. A great deal of testing and licensing would be needed before any thorium fuel could enter service, and the World Nuclear Association sees no real commercial incentive for that investment while uranium stays cheap [2]. No commercial power reactor licensed for thorium-based reload fuel was found for this article.

Put the two lists side by side and a pattern appears. The benefits are physical and lasting. The costs are mostly about infrastructure: drivers, shielded plants, and a fuel chain that would have to be built. A country or company will pay those costs only if it needs what thorium offers badly enough. That is the thread that runs through every program still active.

Who Is Pursuing It, and Why

The United States, and why it stopped

It helps to start with the country that walked away. The United States ran most of the early thorium reactors. Shippingport operated from 1977 to 1982. The Molten Salt Reactor Experiment ran from 1965 to 1969. Peach Bottom and Fort St. Vrain burned thorium with enriched uranium in gas-cooled cores [2].

The physics did not end those programs. History did. The American nuclear industry grew out of the weapons program, which needed enriched uranium and plutonium. Oak Ridge’s enrichment plants and the Hanford reactors were built for bombs, and the first commercial power reactors were adapted from the Navy’s submarine reactors [23]. Oak Ridge National Laboratory itself was founded in the war with one mission, to show that plutonium could be made safely [25]. A fuel cycle that made little plutonium was, in that setting, a drawback [23].

Thorium’s strongest advocate lost his place in the early 1970s. Alvin Weinberg directed Oak Ridge National Laboratory and led its molten salt reactor program [26]. His growing concern about reactor safety put him at odds with the Atomic Energy Commission. In 1972 Union Carbide, which ran the laboratory for the Commission, told him he was being fired, and he resigned in December 1973 [24]. His molten salt breeder also competed with the fast breeder the Commission had made its priority [22] [23].

The Commission’s own reasons were technical and budgetary. It wanted fewer breeder candidates, and it judged the molten salt breeder’s projected breeding ratio low compared with fast reactors [22]. It ordered Oak Ridge to stop the work in January 1973, revived it briefly, and shut it down again in 1976 for budget reasons [22].

Underneath all of this was the point the IAEA makes: uranium turned out to be plentiful [3]. Once enrichment plants, fuel factories, regulations and trained crews were all built around uranium, any alternative had to compete with those institutions, not just with uranium’s physics [23]. Thorium never got a reason to catch up. The countries still pursuing it are the ones that have such a reason. Chapter 3 of the book tells this history at more length.

India: self-sufficiency, not just geology

India is the clearest case, and its reason is as much political as geological. It holds one of the world’s largest thorium resources. Its uranium resources are modest, about 293,000 tonnes in the Red Book [4]. Table 2 gives three published figures for its thorium, which differ because they count different things [1] [2] [4].

TABLE 2. India’s thorium resource, three ways.

Source	Basis	India’s thorium
Government reply to parliament, 2014	Monazite deposits established by the Atomic Minerals Directorate	About 1.07 million tonnes [1]
World Nuclear Association, from the 2016 Red Book	Identified resources in situ, all categories	846,000 tonnes, the largest entry in a world total of about 6.36 million tonnes [2]
World Nuclear Association, India page	Reasonably assured resources	319,000 tonnes, about 13 percent of the world total [4]

The politics made the geology matter. India stayed outside the Non-Proliferation Treaty. After its 1974 nuclear test, the Nuclear Suppliers Group was formed and began to regulate nuclear trade, particularly with India [4]. For 34 years India was largely cut off from trade in nuclear plant and materials, until a waiver in September 2008 [4]. A country that cannot rely on buying uranium has every reason to plan around the fuel it has at home.

The plan is in three stages. Stage one burns natural uranium in heavy water reactors. Stage two burns the plutonium from stage one in fast breeder reactors, building up more fissile material. Stage three uses that material to drive thorium, breeding uranium-233 [1] [2]. Notably, India reaffirmed the thorium plan in 2009, after the trade restrictions were eased [2].

The second stage has just begun. The Prototype Fast Breeder Reactor (PFBR) at Kalpakkam, a sodium-cooled reactor of 500 megawatts electric, reached first criticality on 6 April 2026 [6]. Construction had started in 2004, against a plan to operate in 2010 [5]. A parliamentary committee put its cost at 81.81 billion rupees, more than twice the original estimate [5].

The reactor does not yet use thorium. Its core is uranium-plutonium mixed oxide and its blanket, the outer layer where breeding happens, is uranium-238. The Department of Atomic Energy says it is “designed to eventually use Thorium-232 in the blanket” [6]. For now it breeds plutonium. The operator planned to feed power to the grid in phases from December 2026 [7].

The third stage is still on paper. The Advanced Heavy Water Reactor (AHWR), a design of 300 megawatts electric, would draw about 75 percent of its power from thorium [2]. In August 2025 India’s minister told parliament that it “is not formally launched” [9]. In 2013 the Bhabha Atomic Research Centre put thorium deployment beyond 2070 [4].

India does run one reactor on uranium-233 today. KAMINI, a 30-kilowatt research reactor at Kalpakkam, has operated since 1996 on about 600 grams of uranium-233, bred from thorium irradiated in India [2] [3]. The World Nuclear Association calls it the only uranium-233-fuelled reactor in the world [2]. India has also used thoria bundles in the first cores of its heavy water reactors to even out power at start-up [3].

India’s path shows the cost of the driver in plain terms. Stage three cannot start until stage two has bred enough fissile material, and stage two has only just reached criticality. That leads to the other large program, which is trying a different route.

China: the molten salt route

China’s interest follows the second and third advantages: breeding with slow neutrons, and a liquid fuel that sidesteps the hardest steps of solid thoria. In a molten salt reactor the fuel is dissolved in the salt. The World Nuclear Association notes that this avoids normal fuel fabrication, and that the salt can pass through a chemical processing circuit that removes fission products and recovers uranium-233 while the reactor runs [2].

That answers two of thorium’s costs at once: no shielded pellet plant and no dissolving of thoria. The World Nuclear Association says some of the handling problems are overcome in molten salt designs, though online processing is more complex than the uranium–plutonium cycle [2].

The Shanghai Institute of Applied Physics (SINAP) runs TMSR-LF1, a molten salt reactor with a heat output of 2 megawatts at Wuwei in Gansu province [10]. Table 3 gives its dated steps. The Chinese Academy of Sciences launched the program in January 2011 and has described it as the world’s largest national effort on thorium molten salt reactors [2].

TABLE 3. TMSR-LF1: dated steps.

Date	Step
January 2020	Construction starts, after the construction licence [11]
June 2023	Operating licence [11]
11 October 2023	First criticality [10] [11]
June 2024	Full power [11]
October 2024	First thorium added to the operating reactor [11]
1 November 2025	SINAP announces the first conversion of thorium to uranium fuel in a molten salt reactor [10] [11]

The scale is small, and the result is preliminary. The reactor is driven by uranium enriched to under 20 percent uranium-235 and holds about 50 kilograms of thorium [13]. Its conversion ratio, new fissile atoms made per atom burned, is about 0.1, far below the more than one a breeder needs [13]. SINAP has not released detailed data on the conversion it announced [10] [12].

The next step is planned but not yet licensed. A SINAP environmental impact report posted in November 2024 describes a small thorium molten salt research reactor of 10 megawatts electric, aiming for full power in 2030 [14]. No construction licence for it was found. SINAP’s director has named a demonstration of 100 megawatts of heat by 2035 as the step after that [10].

Companies: each with its own reason

The private efforts each pick one of thorium’s advantages and build around it. None has a reactor running.

Clean Core Thorium Energy is after the fuel material, without the recycling. Its ANEEL fuel mixes thorium with HALEU, high-assay low-enriched uranium, in bundles for heavy water reactors, and is meant to be used once [15]. Test rodlets went into Idaho National Laboratory’s Advanced Test Reactor in May 2024, and the last four passed 60 gigawatt-days per tonne in 2026 [15]. Burnup, measured in gigawatt-days per tonne, is the energy taken from each tonne of fuel.

In October 2026 the company reported that the laboratory’s examinations showed less cracking and swelling than in a uranium dioxide comparison pellet [16]. That interpretation is the company’s. A once-through fuel also gives up thorium’s breeding: India’s AHWR300-LEU, a similar idea, would take only about 39 percent of its power from thorium [4].

Copenhagen Atomics, in Denmark, and Thorizon, in the Netherlands, are after the molten salt fit. Copenhagen Atomics agreed in July 2024 to work with the Paul Scherrer Institute toward a critical experiment targeted for 2026 or 2027 [17]. Thorizon plans a cartridge-core molten salt reactor and aims to start building by 2030 [18]. Flibe Energy, in the United States, develops a lithium fluoride thorium reactor; in May 2026 the Department of Energy selected it for talks on using surplus plutonium as fuel [19]. Plutonium, in that case, would be the driver.

One company shows the pull the other way. ThorCon’s planned plant in Indonesia included thorium in a 2015 design, but its current design uses uranium enriched to 5 percent [20]. When a company needs a licensable reactor soon, the uranium cycle that already exists is the easier choice.

TABLE 4. Thorium programs by status, driver and reason.

Program	Status	Fissile driver	What it is after
KAMINI, India	Operating since 1996 [2]	Uranium-233	Research on a uranium-233 core
PFBR, India	Critical 6 April 2026; breeding plutonium; thorium blanket a design intent [6]	Plutonium	Stage two: fissile material for a future thorium stage
AHWR-300, India	Design; not formally launched (August 2025) [9]	Plutonium or uranium-233	Stage three: power mostly from thorium
TMSR-LF1, China	Operating (experimental); conversion announced 1 November 2025 [10]	Uranium under 20 percent uranium-235	Thermal breeding in a liquid fuel
ANEEL fuel (Clean Core)	Irradiation test; results reported 14 October 2026 [16]	HALEU	Better fuel material, used once
Copenhagen Atomics; Thorizon	Design [17] [18]	Uranium (Copenhagen Atomics); not stated (Thorizon)	Molten salt fit
Flibe Energy	Design; DOE selection 27 May 2026 [19]	Plutonium	Molten salt fit; burning surplus plutonium
Shippingport; MSRE; Peach Bottom; Fort St. Vrain; AVR; THTR; Halden tests	Ended, last in 2018 [2] [21]	Uranium-233, enriched uranium or plutonium	Past demonstrations

What This Means

So why pursue thorium? Because it does things uranium cannot. It breeds with slow neutrons, it leaves fewer long-lived actinides, and its oxide is a sturdier fuel and waste form [2] [3]. Those are settled physics, not claims.

But each advantage pays off only under particular conditions. Breeding pays off only if you recycle uranium-233, and that means shielded, remote plants and a hard-to-dissolve oxide, or a molten salt reactor built for the job. Abundance pays off only if uranium is hard to get. That is why the United States, with cheap uranium and a working uranium industry, stopped, and why India, cut off from uranium for 34 years, kept going [3] [4] [22].

Today the picture is small. One research reactor runs on uranium-233, one experimental reactor holds about 50 kilograms of thorium, and India’s breeder has reached criticality without any thorium in it yet [2] [6] [13]. The things to watch are the first thorium loaded into the PFBR blanket, measured conversion data from TMSR-LF1, a construction licence for China’s next reactor, and a formal launch of the AHWR.

Notes

1. Lok Sabha, Unstarred Question No. 1669, “Generation of Atomic Energy through Thorium,” answered 3 December 2014. https://eparlib.nic.in/bitstream/123456789/709589/1/7805.pdf

2. World Nuclear Association, “Thorium,” Information Library, updated 1 October 2026; includes the Red Book 2016 resource table and the historical reactor record. https://world-nuclear.org/information-library/current-and-future-generation/thorium

3. International Atomic Energy Agency, “Thorium fuel cycle — Potential benefits and challenges,” IAEA-TECDOC-1450, May 2005. https://www-pub.iaea.org/MTCD/Publications/PDF/TE_1450_web.pdf

4. World Nuclear Association, “Nuclear Power in India,” Information Library, updated 15 July 2026; cited for thorium resources, the AHWR, thoria irradiation in PHWRs and BARC’s deployment timing. https://world-nuclear.org/information-library/country-profiles/countries-g-n/india

5. International Panel on Fissile Materials, “India’s Prototype Fast Breeder Reactor reaches criticality – over 15 years behind schedule,” IPFM Blog, April 2026; cites the Parliamentary Standing Committee on cost and the fuel cycle facility. https://fissilematerials.org/blog/2026/04/indias_prototype_fast_bre_2.html

6. Department of Atomic Energy, Government of India, “Prototype Fast Breeder Reactor at Kalpakkam, Tamil Nadu attains First Criticality,” April 2026. https://dae.gov.in/prototype-fast-breeder-reactor-at-kalpakkam-tamil-nadu-attains-first-criticality/

7. DT Next, “BHAVINI seeks transmission line operation ahead of Kalpakkam PFBR launch,” 27 May 2026; reports the minutes of the 238th Operation Coordination Committee meeting of 11 May 2026. https://www.dtnext.in/news/tamilnadu/bhavini-seeks-transmission-line-operation-before-pfbr-deadline

8. News Karnataka, “Kalpakkam PFBR targets March 2027 completion,” 1 October 2026; general news report of a July 2026 parliamentary reply, not itself retrieved. https://newskarnataka.com/india/kalpakkam-pfbr-targets-march-2027-completion/01102026/

9. Nuclear Engineering International, “More delays for India’s PFBR,” 7 August 2025; also reports the minister’s statement on the AHWR. https://www.neimagazine.com/news/more-delays-for-indias-pfbr/

10. World Nuclear News, “Chinese molten salt reactor achieves conversion of thorium-uranium fuel,” 4 November 2025. https://www.world-nuclear-news.org/articles/chinese-msr-achieves-conversion-of-thorium-uranium-fuel

11. Chinanews (中国新闻网), “国际首次、目前唯一 中国建成钍基熔盐实验堆引领世界” (“First in the world, currently the only one: China builds a thorium molten salt experimental reactor that leads the world”), 1 November 2025. https://www.chinanews.com.cn/sh/2025/11-01/10508065.shtml

12. POWER Magazine, “China’s Molten Salt Reactor Reaches Thorium-Uranium Conversion Milestone,” November 2025. https://www.powermag.com/chinas-molten-salt-reactor-reaches-thorium-uranium-conversion-milestone/

13. World Nuclear News, “Operating permit issued for Chinese molten salt reactor,” 15 June 2023. https://www.world-nuclear-news.org/Articles/Operating-permit-issued-for-Chinese-molten-salt-re

14. Shanghai Institute of Applied Physics, environmental impact report (siting stage) for the small modular thorium molten salt reactor research facility (小型模块化钍基熔盐堆研究设施环境影响报告书（选址阶段）), posted by the Ministry of Ecology and Environment, November 2024. https://www.mee.gov.cn/ywdt/gsgg/gongshi/gsq/202411/W020241126360387490476.pdf

15. World Nuclear News, “Innovative thorium-based fuel concludes irradiation campaign,” 7 May 2026. https://www.world-nuclear-news.org/articles/innovative-thorium-based-fuel-concludes-irradiation-campaign

16. Clean Core Thorium Energy, “CCTE’s Thorium Fuel Demonstrates Unprecedented Fuel Performance and Remains Intact Beyond 45 GWd/MTU at Idaho National Laboratory,” GlobeNewswire, 14 October 2026. https://www.globenewswire.com/news-release/2026/10/14/3380707/0/en/ccte-s-thorium-fuel-demonstrates-unprecedented-fuel-performance-and-remains-intact-beyond-45-gwd-mtu-at-idaho-national-laboratory.html

17. World Nuclear News, “Copenhagen Atomics enlists PSI to validate reactor technology,” 1 July 2024. https://www.world-nuclear-news.org/articles/copenhagen-atomics-enlists-psi-to-validate-reactor

18. World Nuclear News, “New funding to advance Thorizon molten salt reactor development,” 12 March 2025. https://wnn.world-nuclear.org/articles/new-funding-to-advance-thorizon-molten-salt-reactor-development

19. Flibe Energy, “Flibe Energy Selected for DOE Surplus Plutonium Utilization Program,” 27 May 2026. https://flibe.com/news/fei-spup-1/

20. Nuclear Engineering International, “Site approval for ThorCon NPP,” 6 August 2025. https://www.neimagazine.com/news/thorcon-clears-first-hurdle/

21. World Nuclear News, “Third round of thorium test irradiation starts,” 31 January 2018; also recounts the earlier rounds from 2013. https://world-nuclear-news.org/articles/third-round-of-thorium-test-irradiation-starts

22. Thomas B. Cochran, Harold A. Feiveson, Walt Patterson, Gennadi Pshakin, M.V. Ramana, Mycle Schneider, Tatsujiro Suzuki and Frank von Hippel, “Fast Reactor Development in the United States,” Science & Global Security 18(1), 2010; covers the light-water and molten salt breeder programs and the AEC’s 1973 and 1976 decisions. https://www.tandfonline.com/doi/full/10.1080/08929880903445514

23. J. Hill, The Nuclear Fuel Cycle: A Complete Primer, Chapter 3, “Beyond Uranium”, section on why uranium won (weapons-first origin, military infrastructure, Weinberg, path dependency).

24. National Academy of Engineering, “Alvin M. Weinberg (1915–2006),” Memorial Tributes, Volume 12, National Academies Press, 2008. https://www.nationalacademies.org/read/12473/chapter/56

25. Oak Ridge National Laboratory, “State of the Laboratory – 1973,” ORNL Review 7(1), 1974; Weinberg’s resignation and the laboratory’s wartime plutonium mission. https://www.ornl.gov/sites/default/files/ORNL%20Review%20v7n1%201974.pdf

26. Oak Ridge National Laboratory, “Time Warp: Molten Salt Reactor Experiment—Alvin Weinberg’s magnum opus,” ORNL blog. https://www.ornl.gov/blog/time-warp-molten-salt-reactor-experiment-alvin-weinbergs-magnum-opus