Thorium-based nuclear power

Thorium-based nuclear power generation is fueled primarily by the nuclear fission of the isotope uranium-233 produced from the fertile element thorium. A thorium fuel cycle can offer several potential advantages over a uranium fuel cycle
 —including much greater abundance of thorium found on Earth, superior physical and nuclear fuel properties, and reduced nuclear waste production. One advantage of thorium fuel is its low weaponization potential; it is difficult to weaponize the uranium-233/232 and plutonium-238 isotopes largely consumed in thorium reactors. 
Between 1999 and , the number of operational thorium reactors in the world has risen from zero, to a handful of research reactors, to commercial plans for producing full-scale thorium-based reactors for use as power plants on a national scale. 
Some believe thorium is key to developing a new generation of cleaner, safer nuclear power. In 2011 a group of scientists at the Georgia Institute of Technology assessed thorium-based power as "a 1000+ year solution or a quality low-carbon bridge to truly sustainable energy sources solving a huge portion of mankind’s negative environmental impact." However, development of thorium power has significant start-up costs. Development of breeder reactors in general (including thorium reactors, which are breeders by nature) will increase proliferation concerns. 
After studying the feasibility of using thorium, nuclear scientists Ralph W. Moir and Edward Teller suggested that thorium nuclear research should be restarted after a three-decade shutdown and that a small prototype plant should be built.
Background and brief history.
After World War II, uranium-based nuclear reactors were built to produce electricity. These were similar to the reactor designs that produced material for nuclear weapons. During that period, the government of the United States also built an experimental molten salt reactor using U-233 fuel, the fissile material created by bombarding thorium with neutrons. The MSRE reactor, built at Oak Ridge National Laboratory, operated critical for roughly 15,000 hours from 1965 to 1969. In 1968, Nobel laureate and discoverer of plutonium, Glenn Seaborg, publicly announced to the Atomic Energy Commission, of which he was chairman, that the thorium-based reactor had been successfully developed and tested.
In 1973, however, the US government settled on uranium technology and largely discontinued thorium-related nuclear research. The reasons were that uranium-fueled reactors were more efficient, the research was proven, and thorium's breeding ratio was thought insufficient to produce enough fuel to support development of a commercial nuclear industry. As Moir and Teller later wrote, "The competition came down to a liquid metal fast breeder reactor (LMFBR) on the uranium-plutonium cycle and a thermal reactor on the thorium-233U cycle, the molten salt breeder reactor. The LMFBR had a larger breeding rate ... and won the competition." In their opinion, the decision to stop development of thorium reactors, at least as a backup option, “was an excusable mistake.”
Science writer Richard Martin states that nuclear physicist Alvin Weinberg, who was director at Oak Ridge and primarily responsible for the new reactor, lost his job as director because he championed development of the safer thorium reactors. Weinberg himself recalls this period:
Martin explains that Weinberg's unwillingness to sacrifice potentially safe nuclear power for the benefit of military uses forced him to retire:
Despite the documented history of thorium nuclear power, many of today's nuclear experts were nonetheless unaware of it. According to "Chemical & Engineering News", "most people—including scientists—have hardly heard of the heavy-metal element and know little about it...," noting a comment by a conference attendee that "it's possible to have a Ph.D. in nuclear reactor technology and not know about thorium energy." Nuclear physicist Victor J. Stenger, for one, first learned of it in 2012:
Others, including former NASA scientist and thorium expert Kirk Sorensen, agree that "thorium was the alternative path that was not taken … " According to Sorensen, during a documentary interview, he states that if the US had not discontinued its research in 1974 it could have "probably achieved energy independence by around 2000."
Possible benefits.
The World Nuclear Association explains some of the possible benefits
Moir and Teller agree, noting that the possible advantages of thorium include "utilization of an abundant fuel, inaccessibility of that fuel to terrorists or for diversion to weapons use, together with good economics and safety features … "
Thorium is considered the "most abundant, most readily available, cleanest, and safest energy source on Earth," adds science writer Richard Martin.
Summarizing some of the potential benefits, Martin offers his general opinion: "Thorium could provide a clean and effectively limitless source of power while allaying all public concern—weapons proliferation, radioactive pollution, toxic waste, and fuel that is both costly and complicated to process. Moir and Teller estimated in 2004 that the cost for their recommended prototype would be "well under $1 billion with operation costs likely on the order of $100 million per year," and as a result a "large-scale nuclear power plan" usable by many countries could be set up within a decade.
A report by the Bellona Foundation in 2013 concluded that the economics are quite speculative. Thorium nuclear reactors are unlikely to produce cheaper energy, but the management of spent fuel is likely to be cheaper than for uranium nuclear reactors.
Possible disadvantages.
Some experts note possible specific disadvantages of thorium nuclear power:
Thorium-based nuclear power projects.
Research and development of thorium-based nuclear reactors, primarily the Liquid fluoride thorium reactor (LFTR), MSR design, has been or is now being done in the United States, United Kingdom, Germany, Brazil, India, China, France, the Czech Republic, Japan, Russia, Canada, Israel, Denmark and the Netherlands. Conferences with experts from as many as 32 countries are held, including one by the European Organization for Nuclear Research (CERN) in 2013, which focuses on thorium as an alternative nuclear technology without requiring production of nuclear waste. Recognized experts, such as Hans Blix, former head of the International Atomic Energy Agency, calls for expanded support of new nuclear power technology, and states, "the thorium option offers the world not only a new sustainable supply of fuel for nuclear power but also one that makes better use of the fuel's energy content."
Canada.
CANDU reactors are capable of using thorium, and Thorium Power Canada has, in 2013, planned and proposed developing thorium power projects for Chile and Indonesia. The proposed 10 MW demonstration reactor in Chile could be used to power a 20 million litre/day desalination plant. In 2018, the New Brunswick Energy Solutions Corporation announced the participation of Moltex Energy in the nuclear research cluster that will work on research and development on small modular reactor technology.
China.
At the 2011 annual conference of the Chinese Academy of Sciences, it was announced that "China has initiated a research and development project in thorium MSR technology." In addition, Dr. Jiang Mianheng, son of China's former leader Jiang Zemin, led a thorium delegation in non-disclosure talks at Oak Ridge National Laboratory, Tennessee, and by late 2013 China had officially partnered with Oak Ridge to aid China in its own development. The World Nuclear Association notes that the China Academy of Sciences in January 2011 announced its R&D program, "claiming to have the world's largest national effort on it, hoping to obtain full intellectual property rights on the technology." According to Martin, "China has made clear its intention to go it alone," adding that China already has a monopoly over most of the world's rare earth minerals.
In March 2014, with their reliance on coal-fired power having become a major cause of their current "smog crisis," they reduced their original goal of creating a working reactor from 25 years down to 10. "In the past, the government was interested in nuclear power because of the energy shortage. Now they are more interested because of smog," said Professor Li Zhong, a scientist working on the project. "This is definitely a race," he added.
In early 2012, it was reported that China, using components produced by the West and Russia, planned to build two prototype thorium MSRs by 2015, and had budgeted the project at $400 million and requiring 400 workers." China also finalized an agreement with a Canadian nuclear technology company to develop improved CANDU reactors using thorium and uranium as a fuel.
Currently two reactors are under construction in the Gobi desert, with completion expected in 2020. China expects to put thorium reactors into commercial use by 2030.
Germany, 1980s.
The German THTR-300 was a prototype commercial power station using thorium as fertile and highly enriched U-235 as fissile fuel. Though named thorium high temperature reactor, mostly U-235 was fissioned. The THTR-300 was a helium-cooled high-temperature reactor with a pebble-bed reactor core consisting of approximately 670,000 spherical fuel compacts each 6 centimetres (2.4 in) in diameter with particles of uranium-235 and thorium-232 fuel embedded in a graphite matrix.
It fed power to Germany's grid for 432 days in the late 1980s, before it was shut down for cost, mechanical and other reasons.
India.
India has the largest supplies of thorium in the world, with comparatively poor quantities of uranium. India has projected meeting as much as 30% of its electrical demands through thorium by 2050.
In February 2014, Bhabha Atomic Research Centre (BARC), in Mumbai, India, presented their latest design for a "next-generation nuclear reactor" that burns thorium as its fuel ore, calling it the Advanced Heavy Water Reactor (AHWR). They estimated the reactor could function without an operator for 120 days. Validation of its core reactor physics was underway by late 2017.
According to Dr R K Sinha, chairman of their Atomic Energy Commission, "This will reduce our dependence on fossil fuels, mostly imported, and will be a major contribution to global efforts to combat climate change." Because of its inherent safety, they expect that similar designs could be set up "within" populated cities, like Mumbai or Delhi.
India's government is also developing up to 62, mostly thorium reactors, which it expects to be operational by 2025. India is the "only country in the world with a detailed, funded, government-approved plan" to focus on thorium-based nuclear power. The country currently gets under 2% of its electricity from nuclear power, with the rest coming from coal (60%), hydroelectricity (16%), other renewable sources (12%) and natural gas (9%). It expects to produce around 25% of its electricity from nuclear power. In 2009 the chairman of the Indian Atomic Energy Commission said that India has a "long-term objective goal of becoming energy-independent based on its vast thorium resources to meet India's economic ambitions."
In late June 2012, India announced that their "first commercial fast reactor" was near completion making India the most advanced country in thorium research. "We have huge reserves of thorium. The challenge is to develop technology for converting this to fissile material," stated their former Chairman of India's Atomic Energy Commission. That vision of using thorium in place of uranium was set out in the 1950s by physicist Homi Bhabha. India's first commercial fast breeder reactor—the 500 MWe Prototype Fast Breeder Reactor (PFBR)—is approaching completion at the Indira Gandhi Centre for Atomic Research, Kalpakkam, Tamil Nadu.
As of July 2013 the major equipment of the PFBR had been erected and the loading of "dummy" fuels in peripheral locations was in progress. The reactor was expected to go critical by September 2014. The Centre had sanctioned Rs. 5,677 crore for building the PFBR and “we will definitely build the reactor within that amount,” Mr. Kumar asserted. The original cost of the project was Rs. 3,492 crore, revised to Rs. 5,677 crore. Electricity generated from the PFBR would be sold to the State Electricity Boards at Rs. 4.44 a unit. BHAVINI builds breeder reactors in India.
In 2013 India's 300 MWe AHWR (pressurized heavy water reactor) was slated to be built at an undisclosed location. The design envisages a start up with reactor grade plutonium that breeds U-233 from Th-232. Thereafter, thorium is to be the only fuel. As of 2017, the design was in the final stages of validation.
Delays have since postponed the commissioning [criticality?] of the PFBR to September 2016, but India's commitment to long-term nuclear energy production is underscored by the approval in 2015 of ten new sites for reactors of unspecified types, though procurement of primary fissile material—preferably plutonium—may be problematic due to India's low uranium reserves and capacity for production.
Indonesia.
P3Tek, an agency of the Indonesia Ministry of Energy and Mineral Resource, has reviewed a thorium molten salt reactor by Thorcon called the TMSR-500. The study reported that building a ThorCon TMSR-500 would meet Indonesia's regulations for nuclear energy safety and performance.
Israel.
In May 2010, researchers from Ben-Gurion University of the Negev in Israel and Brookhaven National Laboratory in New York began to collaborate on the development of thorium reactors, aimed at being self-sustaining, "meaning one that will produce and consume about the same amounts of fuel," which is not possible with uranium in a light water reactor.
Japan.
In June 2012, Japan utility Chubu Electric Power wrote that they regard thorium as "one of future possible energy resources."
Norway.
In late 2012, Norway's privately owned Thor Energy, in collaboration with the government and Westinghouse, announced a four-year trial using thorium in an existing nuclear reactor." In 2013, Aker Solutions purchased patents from Nobel Prize winning physicist Carlo Rubbia for the design of a proton accelerator-based thorium nuclear power plant.
United Kingdom.
In Britain, one organisation promoting or examining research on thorium-based nuclear plants is The Alvin Weinberg Foundation. House of Lords member Bryony Worthington is promoting thorium, calling it “the forgotten fuel” that could alter Britain's energy plans. However, in 2010, the UK's National Nuclear Laboratory (NNL) concluded that for the short to medium term, "...the thorium fuel cycle does not currently have a role to play," in that it is "technically immature, and would require a significant financial investment and risk without clear benefits," and concluded that the benefits have been "overstated." Friends of the Earth UK considers research into it as "useful" as a fallback option.
United States.
In its January 2012 report to the United States Secretary of Energy, the Blue Ribbon Commission on America's Future notes that a "molten-salt reactor using thorium [has] also been proposed." That same month it was reported that the US Department of Energy is "quietly collaborating with China" on thorium-based nuclear power designs using an MSR.
Some experts and politicians want thorium to be "the pillar of the U.S. nuclear future." Senators Harry Reid and Orrin Hatch have supported using $250 million in federal research funds to revive ORNL research. In 2009, Congressman Joe Sestak unsuccessfully attempted to secure funding for research and development of a destroyer-sized reactor [reactor of a size to power a destroyer] using thorium-based liquid fuel.
Alvin Radkowsky, chief designer of the world's second full-scale atomic electric power plant in Shippingport, Pennsylvania, founded a joint US and Russian project in 1997 to create a thorium-based reactor, considered a "creative breakthrough." In 1992, while a resident professor in Tel Aviv, Israel, he founded the US company, Thorium Power Ltd., near Washington, D.C., to build thorium reactors.
The primary fuel of the proposed HT3R research project near Odessa, Texas, United States, will be ceramic-coated thorium beads. The reactor construction has not yet begun. Estimates to complete a reactor were originally set at ten years in 2006 (with a proposed operational date of 2015).
On the research potential of thorium-based nuclear power, Richard L. Garwin, winner of the Presidential Medal of Freedom, and Georges Charpak advise further study of the Energy amplifier in their book Megawatts and Megatons (2001), pp. 153–63.
World sources of thorium.
Thorium is mostly found with the rare earth phosphate mineral, monazite, which contains up to about 12% thorium phosphate, but 6–7% on average. World monazite resources are estimated to be about 12 million tons, two-thirds of which are in heavy mineral sands deposits on the south and east coasts of India. There are substantial deposits in several other countries "(see table "World thorium reserves")". Monazite is a good source of REEs (Rare Earth Element), but monazites are currently not economical to produce because the radioactive thorium that is produced as a byproduct would have to be stored indefinitely. However, if thorium-based power plants were adopted on a large-scale, virtually all the world's thorium requirements could be supplied simply by refining monazites for their more valuable REEs.
Another estimate of reasonably assured reserves (RAR) and estimated additional reserves (EAR) of thorium comes from OECD/NEA, Nuclear Energy, "Trends in Nuclear Fuel Cycle", Paris, France (2001). "(see table "IAEA Estimates in tons")"
The preceding figures are reserves and as such refer to the amount of thorium in high-concentration deposits inventoried so far and estimated to be extractable at current market prices; millions of times more total exist in Earth's 3 tonne crust, around 120 trillion tons of thorium, and lesser but vast quantities of thorium exist at intermediate concentrations. Proved reserves are a good indicator of the total future supply of a mineral resource.
Types of thorium-based reactors.
According to the World Nuclear Association, there are seven types of reactors that can be designed to use thorium as a nuclear fuel. Six of these have all entered into operational service at some point. The seventh is still conceptual, although currently in development by many countries: