The Liquid Fluoride Thorium Reactor
http://www.thoriumsingapore.com/content/index.php?option=com_content&view=article&id=50&Itemid=37
Nuclear energy
Nuclear Power Is Extremely Safe — That’s the Truth About What We Learned From Japan
http://thorium.klimabedrag.dk/
In the midst of a still struggling and fragile global economy, Germany has announced that it will shut down seven nuclear plants by the end of the year – which means that Germans will be left to run their factories, heat their homes, and power their economy with 10% less electrical generating capacity. Nine more plants will be shut down over the next decade and tens of billions of dollars in investment will be lost.
The grounds for this move, and similar proposals in Switzerland, Italy, and other countries, is safety. As the Swiss energy minister put it, “Fukushima showed that the risk of nuclear power is too high.”
In fact, Fukushima showed just the opposite. How’s that? Well for starters, ask yourself what the death toll was at Fukushima. 100? 200? 10? Not true. Try zero.
To think rationally about nuclear safety, you must identify the whole context. As the late, great energy thinker Petr Beckmann argued three decades ago in his contrarian classic “The Health Hazards of NOT Going Nuclear,” every means of generating power has dangers and risks, but nuclear power “is far safer than any other form of large-scale energy conversion yet invented.”
To date, there have been devised only five practical means of producing large-scale, affordable, reliable energy: coal, natural gas, oil, hydroelectric, and nuclear. (Although widely hyped and frequently subsidized, solar and wind power – which generate energy from highly diffuse and intermittent sources – have failed for forty years to deliver.) Whether you’re concerned about a dangerous accident or harmful emissions, a nuclear power plant is the safest way to generate power.
The key to nuclear power’s safety, Beckmann explains, is that it uses a radioactive energy source – such as uranium. In addition to having the advantage of storing millions of times more energy per unit of volume than coal, gas, or water, the radioactive material used in power plants literally cannot explode. Ridiculing the scare tactics that a nuclear power plant poses the same dangers as a nuclear bomb, Beckmann observes: “An explosive nuclear chain reaction is no more feasible in the type of uranium used as power plant fuel than it is in chewing gum or pickled cucumbers.”
The one danger of running a nuclear plant is a large release of radiation. This is extremely unlikely, because nuclear plants contain numerous shielding and containment mechanisms (universal in the civilized world but callously foregone by the Soviets in their Chernobyl plant).
But in the most adverse circumstances, as Fukushima illustrated, the cooling system designed to moderate the uranium’s heat can fail, the backups can fail, the radioactive material can overheat to the point that the plant cannot handle the pressure, and a radiation release is necessary.
Yet, even then, it is extremely unlikely that the radiation levels will be high enough to cause radiation sickness or cancer – and radiation in modest quantities is a normal, perfectly healthy feature of life (your blood is radioactive, as is the sun). And even the worst nuclear accident gives neighbors a luxury that broken dams and exploding refineries do not: time.
….
While many, many things went wrong at Fukushima, as might be expected in an unprecedented natural disaster, what is more remarkable is that thanks to the fundamental integrity of the nuclear vessel and the containment building, none of the power plant’s neighbors have died, nor have any apparently been exposed to harmful levels of radiation. (The Japanese government has announced that eight of 2,400 workers have been exposed to higher-than-allowed amounts of radiation, but these amounts are often hundreds of times less than is necessary to do actual damage.)
Now imagine if a 9.0 earthquake and 40 foot tsunami had hit a hydroelectric dam; thousands of people could have died in the ensuing flood.
….
The Fukushima nuclear plants, with their incredible resilience, almost certainly saved many, many lives.
Nuclear power also saves lives that would otherwise be lost to pollution. A nuclear power plant has effectively zero harmful emissions. (It generates a small amount of waste, which France, among other countries, has demonstrated can be both re-used economically and stored safely.) By contrast, fossil fuel plants generate various forms of particulate matter that strongly correlate with higher cancer rates. We should not “knock coal,” Beckmann stressed, as fossil fuel plants are vital for human survival for decades to come, but we should recognize that new nuclear power plants are far safer than the status quo.
….
As a consequence of the anti-nuclear hysteria in Beckmann’s time, the U.S. government made it either impossible or economically prohibitive to build new plants, in the name of “safety.” Fukushima has affirmed that nuclear is the safest form of power in existence. Any government that fails to recognize this is endangering its citizens’ health.
By Alex Epstein Published July 23, 2011, FoxNews.com
Alex Epstein is a fellow at the Ayn Rand Center for Individual Rights, specializing in energy issues. The Ayn Rand Center is a division of the Ayn Rand Institute.
Read the full article at FoxNews …
New age nuclear
Nuclear energy produces no greenhouse gases, but it has many drawbacks. Now a radical new technology based on thorium promises what uranium never delivered: abundant, safe and clean energy – and a way to burn up old radioactive waste.
Download PDF : Thorium
THORIUM Reactor
Download PDF : THORIUM Reactor
Can We Stop the Next Fukushima Times 10,000?
http://readersupportednews.org/opinion2/271-38/7415-can-we-stop-the-next-fukushima-times-10000
13 Sept. 2011
he horrible news from Japan continues to be ignored by the western corporate media.
Fukushima’s radioactive fallout continues to spread throughout the archipelago, deep into the ocean and around the globe – including the US. It will ultimately impact millions, including many here in North America.
The potentially thankful news is that Fukushima’s three melting cores may have not have melted deep into the earth, thus barely avoiding an unimaginably worse apocalyptic reality.
But it’s a horror that humankind has yet to fully comprehend.
As Fukushima’s owners now claim its three melted reactors approach cold shutdown, think of this:
At numerous sites worldwide – including several in the US – three or more reactors could simultaneously melt, side-by-side. At two sites in California – Diablo Canyon and San Onofre – two reactors each sit very close to major earthquake faults, in coastal tsunami zones.
Should one or more such cores melt through their reactor pressure vessels (as happened at Fukushima) and then through the bottoms of the containments (which, thankfully, may not have happened at Fukushima), thousands of tons of molten radioactive lava would burn into the Earth.
The molten mass(es) would be further fed by thousands of tons of intensely radioactive spent fuel rods stored on site that could melt into the molten masses or be otherwise compromised.
All that lava would soon hit groundwater, causing steam and hydrogen explosions of enormous power.
Those explosions would blow untold quantities of radioactive particles into the global environment, causing apocalyptic damage to all living beings and life support systems on this planet. The unmeasurable clouds would do unimaginable, inescapable injury to all human life.
Fukushima is far from over. There is much at the site still fraught with peril, far from the public eye.
Among other things, Unit Four’s compromised spent fuel pool is perched high in the air. The building is sinking and tilting. Seismic aftershocks could send that whole complex – and much more – tumbling down, with apocalyptic consequences.
Fukushima’s three meltowns and at least four explosions have thus far yielded general radioactive fallout at least 25 times greater than what was released at Hiroshima, involving more than 160 times the cesium, an extremely deadly isotope.
Reuters reports that fallout into the oceans is at least triple what Tokyo Electric has claimed. Airborne cesium and other deadly isotopes have been pouring over the United States since a few scant days after the disaster.
Overall the fallout is far in excess of Chernobyl, which has killed more than a million people since its 1986 explosion.
Within Japan, radioactive hotspots and unexpectedly high levels of fallout continue to surface throughout the archipelago. The toll there and worldwide through the coming centuries will certainly be in the millions.
And yet … it could have been far worse.
In the US, in the past few months, an earthquake has shaken two Virginia reactors beyond their design specifications. Two reactors in Nebraska have been seriously threatened by flooding. Now a lethal explosion has struck a radioactive waste site in France.
We have also just commemorated a 9/11/2001 terror attack that could easily have caused full melt-downs to reactors in areas so heavily populated that millions could have been killed and trillions of dollars in damage could have permanently destroyed the American economy.
The only thing we now know for certain is that there will be more earthquakes, more tsunamis, more floods, hurricanes and tornadoes … and more terror attacks.
Horrifying as Fukushima may be, we also know for certain that the next reactor catastrophe could make even this one pale by comparison.
Japan will never fully recover from Fukushima. Millions of people will be impacted worldwide from its lethal fallout.
But the next time could be worse – MUCH worse.
The only good news is that Japan, Germany, Switzerland, Italy, Sweden and others are dumping atomic power. They are committing to Solartopian technologies – solar, wind, tidal, geothermal, ocean thermal, sustainable bio-fuels, increased efficiency and conservation – that will put their energy supplies in harmony with Mother Earth rather than at war with her.
The rest of humankind must do the same – and fast. Our species can’t survive on this planet – ecologically, economically or in terms of our biological realities – without winning this transtion.
The only question is whether we do it before the next Fukushima times ten thousand makes the whole issue moot.
NukeFree.org was founded in 2007 by Bonnie Raitt, Jackson Browne, Graham Nash and friends to stop a proposed $50 billion loan guarantee package meant to finance new nuclear reactor construction. Joining a successful national grassroots campaign, they established this website and recorded the YouTube video on the home page.
Editor Harvey Wasserman has worked with Bonnie, Jackson, and Graham since the late 1970s and the legendary Musicians United for Safe Energy (MUSE) concerts in Madison Square Garden. This website is meant to inform and inspire those who continue to work for a green-powered Earth, free from the plague of atomic energy. Please feel free to write Harvey with your comments and with URLs for articles you’d like to see appear on these pages.
Are Safer Reactors Possible?
But was the escaped plutonium dangerous? The Guardian reported,
Masayoshi Yamamoto, a professor at Kanazawa University, said the level of plutonium in the sample was lower than average levels observed in Japan after nuclear weapons tests conducted overseas.
In conventional Light Water Reactors plutonium is produced inside fuel pellets. The fuel pellet is a ceramic and in almost every case the fuel plutonium will remain there. The only way the plutonium might escape the fuel pellet, would require that the reactor core overheat to such an extent that the ceramic fuel pellets start to melt. Once the plutonium escapes the fuel pellet, it faces a further barrier, the pressure vessel, which contains the reactor core inside a thick steel wall. If the plutonium managed to get past the wall of the pressure vessel, it would face one or more cement barriers, and then the forces of gravity as it pulled the plutonium to the outside grounds of the nuclear power plant. So how did the plutonium manage to travel a mile away from the Fukushima reactors? The answer is probably because it was ejected from the reactor building by a hydrogen explosion. More likely the plutonium was contained inside the spent fuel pellets that were housed in a pool above the Fukushima reactors. It is far from satisfactory that any plutonium managed to escape from the beyond the grounds of the Fukushima reactors, but in fact the amount that escaped was so tiny that it could do no harm.
So is there anyway, to insure that no plutonium ever escapes from a reactor core? Yes there is, in fact no plutonium can escape from a reactor if plutonium is not produced inside the core. But how is that possible? First while a lot of plutonium is produced in uranium fuel cycle reactors, less than 10% of that amount is produced in the thorium fuel cycle. A 1 GW LFTR would produce about 40 Pounds of Plutonium a year. If the goal is to minimize plutonium production this can be easily done. If the goal is to destroy plutonium, the presence of thorium in a reactor core facilitates the burning of plutonium. Finally if the goal is to produce no plutonium, then the use of fluid fuel thorium breeders (LFTRs) is highly recommended, because Neptunium-237, a plutonium predecessor isotope can be cleaned from a molten salt coolant before it can be converted from neptunium into plutonium by absorbing a neutron. Cleaning NP-237 from molten salt fluid is a relatively easy and low cost procedure. Once out of the LFTR core the neptunium can be destroyed in a burner reactor.
Thus if preventing the escape of plutonium from a reactor core is a major nuclear safety goal, designing molten salt thorium fuel cycle reactors that feature neptunium cleaning from core salts, would prevent the production of plutonium. If there is no plutonium production there can be no escape of plutonium.
Thus we have a choice of safety approaches to plutonium management, with the possibility of complete elimination of plutonium from waste stream a real possibility if it was desirable to do so. Total burn of plutonium would be yet another option.
http://theenergycollective.com/charlesbarton/59635/are-safer-reactors-possible
The Nuclear Disaster That Could Destroy Japan
The Asia-Pacific Journal Vol 9, Issue 21 No 2, May 23, 2011.
Hirose Takashi and C. Douglas Lummis
On the danger of a killer earthquake in the Japanese Archipelago.
Translated and with an introduction by C. Douglas Lummis
(Nuclear) Power Corrupts
A puzzle for our time: how is it possible for a person to be smart enough to make plutonium, and dumb enough actually to make it?
Plutonium has a half life of 24,000 years, which means that in that time its toxicity will be reduced by half. What could possess a person, who will live maybe one three-hundredth of that time, to produce such a thing and leave it to posterity to deal with? In fact, “possess” might be the right word. Behind all the nuclear power industry’s language of cost efficiency or liberation from fossil fuel or whatever, one can sense a kind of possession – a bureaucratized madness. Political science has produced but one candidate for a scientific law – Power Corrupts and Absolute Power Corrupts Absolutely. But the political scientists haven’t noticed that the closest thing we have to absolute power is nuclear power. Nuclear power corrupts in a peculiar way. It seems to tempt the engineers into imagining they have been raised to a higher level, a level where common sense judgments are beneath them. Judgments like (as my grandmother used to say) “Accidents do happen”.
At their press conferences, the Tokyo Electric Co. (Tepco) officials say, as if it were an excuse, that the 3/11 earthquake and tsunami in northeastern Japan were “outside their expectations”. Look it up in the dictionary; that’s the definition of “accident.” For decades common-sense opponents of nuclear power, in Japan and all over the world, have been asking the common-sense question, What if there is an accident? For this they were ridiculed and scorned by the nuclear engineers and their spokespersons. We, suffer an accident? In our world there are no accidents!
Playing with nuclear power is playing God, which is by far the most corrupting game of all.
In Japan, one of the loudest, most persistent and best informed of the voices asking this common sense question has been that of Hirose Takashi. Mr. Hirose first came into public view with a Swiftean satire he published in 1981, Tokyo e, Genpatsu wo! (Nuclear Power Plants to Tokyo!).(Shueisha) In that work, he made the argument that, if it is really true that these plants are perfectly safe (“accidents never happen”) then why not build them in downtown Tokyo rather than in far-off places? By putting them so far away you lose half the electricity in the wires, and waste all that hot water by pumping it into the ocean instead of delivering it to people’s homes where it could be used for baths and cooking. The book outraged a lot of people – especially in Tokyo – and revealed the hypocrisy of the safety argument.
In the years since then he has published volume after volume on the nuclear power issue – particularly focusing on the absurdity of building a facility that requires absolutely no accidents whatsoever, on an archipelago famous as the earthquake capital of the world. Again and again he made frightening predictions which (as he writes in the introduction to his latest book Fukushima Meltdown (Asahi, 2011) he was always praying would prove wrong. Tragically, they did not. In the present article he reminds readers that the recent earthquake was not the last, but one in a series, and that the situation at Japan’s other nuclear power plants is as dangerous as ever. The nuclear power industry would like us to believe the 3/11 catastrophe was an “exception”. But all accidents are exceptions – as will be the next. CDL
C. Douglas Lummis is the author of Radical Democracy and other books in Japanese and English. A Japan Focus associate, he formerly taught at Tsuda College.
Earthquakes and Nuclear Power Plants
The nuclear power plants in Japan are ageing rapidly; like cyborgs, they are barely kept in operation by a continuous replacement of parts. And now that Japan has entered a period of earthquake activity and a major accident could happen at any time, the people live in constant state of anxiety.
Seismologists and geologists agree that, after some fifty years of seismic inactivity, with the 1995 Hanshin-Awaji Earthquake (Southern Hyogo Prefecture Earthquake), the country has entered a period of seismic activity. In 2004, the Chuetsu Earthquake hit Niigata Prefecture, doing damage to the village of Yamakoshi. Three years later, in 2007, the Chuetsu Offshore Earthquake severely damaged the nuclear reactors at Kashiwazaki-Kariwa. In 2008, there was an earthquake in Iwate and Miyagi Prefectures, causing a whole mountain to disappear completely. Then in 2009 the Hamaoka nuclear plant was put in a state of emergency by the Suruga Bay Earthquake. And now, in 2011, we have the 3/11 earthquake offshore from the northeast coast. But the period of seismic activity is expected to continue for decades. From the perspective of seismology, a space of 10 or 15 years is but a moment in time.
Because the Pacific Plate, the largest of the plates that envelop the earth, is in motion, I had predicted that there would be major earthquakes all over the world.
And as I had feared, after the Suruga Bay Earthquake of August 2009 came as a triple shock, it was followed in September and October by earthquakes off Samoa, Sumatra, and Vanuatu, of magnitudes between 7.6 and 8.2. That means three to eleven times the force of the Southern Hyogo Prefecture Earthquake. As you can see in the accompanying chart, all of these quakes occurred around the Pacific Plate as the center, and each was located at the boundary of either that plate or a plate under its influence. Then in the following year, 2010, in January there came the Haiti Earthquake, at the boundary of the Caribbean Plate, pushed by the Pacific and Coco Plates, then in February the huge 8.8 magnitude earthquake offshore from Chile. I was praying that this world scale series of earthquakes would come to an end, but the movement of the Pacific Plate shows no sign of stopping, and led in 2011 to the 3/11 Earthquake in northeastern Japan and the subsequent meltdown at the Fukushima Nuclear Plant.
Is the Rokkasho Reprocessing Plant Safe?
There are large seismic faults, capable of producing earthquakes at the 7 or 8 magnitude level, near each of Japan’s nuclear plants, including the reprocessing plant at Rokkasho. It is hard to believe that there is any nuclear plant that would not be damaged by a magnitude 8 earthquake.
A representative case is the Rokkasho Reprocessing Plant itself, where it has become clear that the fault under the sea nearby also extends inland. The Rokkasho plant, where the nuclear waste (death ash) from all the nuclear plants in Japan is collected, is located on land under which the Pacific Plate and the North American Plate meet. That is, the plate that is the greatest danger to the Rokkasho plant, is now in motion deep beneath Japan.
The Rokkasho plant was originally built with the very low earthquake resistance factor of 375 gals. (Translator’s note: The gal, or galileo, is a unit used to measure peak ground acceleration during earthquakes. Unlike the scales measuring an earthquake’s general intensity, it measures actual ground motion in particular locations.) Today its resistance factor has been raised to only 450 gals, despite the fact that recently in Japan earthquakes registering over 2000 gals have been occurring one after another. Worse, the Shimokita Peninsula is an extremely fragile geologic formation that was at the bottom of the sea as recently as the sea rise of the Jomon period (the Flandrian Transgression) 5000 years ago; if an earthquake occurred there it could be completely destroyed.
The Rokkasho Reprocessing Plant is where expended nuclear fuel from all of Japan’s nuclear power plants is collected, and then reprocessed so as to separate out the plutonium, the uranium, and the remaining highly radioactive liquid waste. In short, it is the most dangerous factory in the world.
At the Rokkasho plant, 240 cubic meters of radioactive liquid waste are now stored. A failure to take care of this properly could lead to a nuclear catastrophe surpassing the meltdown of a reactor. This liquid waste continuously generates heat, and must be constantly cooled. But if an earthquake were to damage the cooling pipes or cut off the electricity, the liquid would begin to boil. According to an analysis prepared by the German nuclear industry, an explosion of this facility could expose persons within a 100 kilometer radius from the plant to radiation 10 to 100 times the lethal level, which presumably means instant death.
On April 7, just one month after the 3/11 earthquake in northeastern Japan, there was a large aftershock. At the Rokkasho Reprocessing Plant the electricity was shut off. The pool containing nuclear fuel and the radioactive liquid waste were (barely) cooled down by the emergency generators, meaning that Japan was brought to the brink of destruction. But the Japanese media, as usual, paid this almost no notice.
The Hamaoka Nuclear Plant and the Approaching Killer Earthquake
The Hamaoka Nuclear Plant is located at Shizuoka City, on Suruga Bay. Despite predictions of a magnitude 8 earthquake on Suruga Bay, it has continued in operation. If you look at the illustration showing the configuration of the plates beneath the Pacific Ocean, you will see that there is a point at which the Philippine Sea Plate, the huge Pacific Plate, the North American Plate, and the Eurasian Plate all meet; directly over that point is the Japanese Archipelago. And the very center of the area where these four plates press together is Shizuoka.
Large scale earthquakes in the eastern and southern seas have occurred regularly at intervals of between 100 and 250 years. Today in 2011, 157 years have passed since the Great Ansei Earthquake of 1854, so we are in a period when the next big one could come at any time. And the predicted center of this expected major earthquake is – though this is hard to believe – exactly under the location of the Hamaoka Nuclear Plant. (Editor’s note: On May 6, 2011, following a request from Prime Minister Kan, the Hamaoka Plant was temporarily closed in light of the prediction that there was an 87% chance that an earthquake of magnitude 8.0 or more would strike the area in the next thirty years.)
And sonar readings at the site indicate that from thirty years back the Eurasian plate has been bending, which means that it is in a condition where it can be expected eventually to spring back.
C. Douglas Lummis is the author of Radical Democracy and other books in Japanese and English. A Japan Focus associate, he formerly taught at Tsuda College.
New regulations urged to force city to cut back on its use of energy
South China Morning Post — April 26, 2011
New regulations are needed to force Hongkongers to cut energy consumption if they don’t want to rely on nuclear power, Council for Sustainable Development chairman Bernard Chan warns.
The former Executive Council member made the comment as concerns mount locally over the use of nuclear power amid the crisis at the Fukushima plant following the devastating quake and tsunami in Japan.
“Increasing nuclear supply is an option for cutting carbon emissions, but clearly the option has now become controversial after the crisis [in Japan],” he said.
Public pressure is intensifying for the Hong Kong government to give up on a target for increasing nuclear use from 23 per cent to 50 per cent of the fuel mix in 10 years. Chan said the controversy could be a blessing in disguise: “It highlights the importance of demand-side control.”
Chan said the council was preparing for a consultation to gauge public views on how the city should tackle climate change in the second half of this year. It will focus on ways to control public demand for energy and make recommendations to the government early next year.
Measures being considered include forcing big consumers such as developers, listed companies and management firms of commercial buildings and shopping malls to audit and disclose their carbon emissions and energy consumption.
Electricity consumed by buildings contributes to about 60 per cent of the city’s greenhouse gas emissions, of which commercial buildings take up 65 per cent.
Apart from tightening existing energy efficiency standards for commercial buildings, the council would also explore the feasibility of installing meters in commercial buildings to measure electricity consumption; establishing best practice guidelines for different industries in energy consumption; and encouraging companies to become carbon-neutral – which means offsetting carbon emissions by investing in green projects.
To set an example, Chan, who is head of Asia Insurance, invested HK$100,000 in a reforestation project in Sichuan province to offset 709 tonnes of carbon emitted by the company in 2009. His company conducted a carbon audit to determine its emissions. He said cutting energy use was far more effective than paying for carbon emissions.
But one obstacle he found was that no matter how much on air conditioning his office saved, the saving would not be reflected on electricity bills as a management company run by the MTR Corp charged an air-conditioning fee in terms of office size but not the amount consumed.
He was also told that it was impossible to install meters to record energy consumed by offices as the management company must gain the consensus of all individual owners of World Wide House, Central, where his office is located.
“There’s a lack of incentive to cut energy. They won’t do it unless we have some mandatory measures that are feasible,” he said.
Thorium
March 2011
http://www.world-nuclear.org/info/inf62.html
Thorium continues to be a tanatalising possibility for use in nuclear power reactors, though for many years India has been the only sponsor of major research efforts to use it. Other endeavours include the development of the Radkowsky Thorium Reactor concept being carried out by US company Thorium Power (now Lightbridge Corporation) with Russian collaboration.
In mid-2009, AECL signed agreements with three Chinese entities to develop and demonstrate the use of thorium fuel in the Candu reactors at Qinshan in China. Another mid-2009 agreement, between Areva and Lightbridge Corporation, was for assessing the use of thorium fuel in Areva’s EPR, drawing upon earlier research. Thorium can also be used in Generation IV and other advanced nuclear fuel cycle systems.
Nature and sources of thorium
Thorium is a naturally-occurring, slightly radioactive metal discovered in 1828 by the Swedish chemist Jons Jakob Berzelius, who named it after Thor, the Norse god of thunder. It is found in small amounts in most rocks and soils, where it is about three times more abundant than uranium. Soil commonly contains an average of around 6 parts per million (ppm) of thorium.
Thorium-232 (Th-232) decays very slowly (its half-life is about three times the age of the Earth) but other thorium isotopes occur in its and in uranium’s decay chains. Most of these are short-lived and hence much more radioactive than Th-232, though on a mass basis they are negligible.
When pure, thorium is a silvery white metal that retains its lustre for several months. However, when it is contaminated with the oxide, thorium slowly tarnishes in air, becoming grey and eventually black. Thorium oxide (ThO2), also called thoria, has one of the highest melting points of all oxides (3300°C). When heated in air, thorium metal turnings ignite and burn brilliantly with a white light. Because of these properties, thorium has found applications in light bulb elements, lantern mantles, arc-light lamps, welding electrodes and heat-resistant ceramics. Glass containing thorium oxide has a high refractive index and dispersion and is used in high quality lenses for cameras and scientific instruments.
The most common source of thorium is the rare earth phosphate mineral, monazite, which contains up to about 12% thorium phosphate, but 6-7% on average. Monazite is found in igneous and other rocks but the richest concentrations are in placer deposits, concentrated by wave and current action with other heavy minerals. World monazite resources are estimated to be about 12 million tonnes, 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 below). Thorium recovery from monazite usually involves leaching with sodium hydroxide at 140°C followed by a complex process to precipitate pure ThO2.
Thorite (ThSiO4) is another common mineral. A large vein deposit of thorium and rare earth metals is in Idaho.
The 2007 IAEA-NEA publication Uranium 2007: Resources, Production and Demand (often referred to as the ‘Red Book’) gives a figure of 4.4 million tonnes of total known and estimated resources, but this excludes data from much of the world. Data for reasonably assured and inferred resources recoverable at a cost of $80/kg Th or less are given in the table below. Some of the figures are based on assumptions and surrogate data for mineral sands, not direct geological data in the same way as most mineral resources.
| (Reasonably assured and inferred resources recoverable at up to $80/kg Th) |
||
| Country | Tonnes | % of total |
| Australia | 489,000 | 19 |
| USA | 400,000 | 15 |
| Turkey | 344,000 | 13 |
| India | 319,000 | 12 |
| Venezuela | 300,000 | 12 |
| Brazil | 302,000 | 12 |
| Norway | 132,000 | 5 |
| Egypt | 100,000 | 4 |
| Russia | 75,000 | 3 |
| Greenland | 54,000 | 2 |
| Canada | 44,000 | 2 |
| South Africa | 18,000 | 1 |
| Other countries | 33,000 | 1 |
| World total
|
2,610,000
Thorium as a nuclear fuelThorium, as well as uranium, can be used as a nuclear fuel. Although not fissile itself, Th-232 will absorb slow neutrons to produce uranium-233 (U-233)a, which is fissile (and long-lived). The irradiated fuel can then be unloaded from the reactor, the U-233 separated from the thorium, and fed back into another reactor as part of a closed fuel cycle. Alternatively, U-233 can be bred from thorium in a blanket, the U-233 separated, and then fed into the core. In one significant respect U-233 is better than uranium-235 and plutonium-239, because of its higher neutron yield per neutron absorbed. Given a start with some other fissile material (U-233, U-235 or Pu-239) as a driver, a breeding cycle similar to but more efficient than that with U-238 and plutonium (in normal, slow neutron reactors) can be set up. (The driver fuels provide all the neutrons initially, but are progressively supplemented by U-233 as it forms from the thorium.) However, there are also features of the neutron economy which counter this advantage. In particular the intermediate product protactinium-233 (Pa-233) is a neutron absorber which diminishes U-233 yield. Over the last 40 years there has been interest in utilising thorium as a nuclear fuel since it is more abundant in the Earth’s crust than uranium. Also, all of the mined thorium is potentially useable in a reactor, compared with the 0.7% of natural uranium in today’s reactorsb, so some 40 times the amount of energy per unit mass might theoretically be available (without recourse to fast neutron reactors). But this relative advantage vanishes if fast neutron reactors are used for uranium. Thorium R&D historyThe use of thorium-based fuel cycles has been studied for about 40 years, but on a much smaller scale than uranium or uranium/plutonium cycles. Basic research and development has been conducted in Germany, India, Japan, Russia, the UK and the USA. Test reactor irradiation of thorium fuel to high burn-ups has also been conducted and several test reactors have either been partially or completely loaded with thorium-based fuel. Noteworthy experiments involving thorium fuel include the following, the first three being high-temperature gas-cooled reactors:
There have also been several experiments with fast neutron reactors. Power reactors Much experience has been gained in thorium-based fuel in power reactors around the world, some using high-enriched uranium (HEU) as the main fuel:
Light Water Breeder Reactor The Light Water Breeder Reactor (LWBR) concept is a major potential application for conventional pressurised water reactors (PWRs) and was successfully demonstrated at the Shippingport reactor in the USA2. Shippingport commenced commercial operation in December 1957 as the first large-scale nuclear power reactor to be operated solely for electricity production. In 1965 the Atomic Energy Commission began designing a uranium-233/thorium core for the reactor and in 1976, the Energy Research and Development Administration (now the Department of Energy) established the Advanced Water Breeder Applications programme to evaluate the LWBR concept for commercial-scale applications. Shippingport operated as an LWBR between August 1977 and October 1982, when the station was finally shut down. During this period, the demonstration LWBR operated for over 29,000 effective full power hours with an availability factor of 76% and had a gross electrical output of over 2.1 billion kilowatt hours. Following operation, inspection of the core found that 1.39% more fissile fuel was present at the end of core life than at the beginning, proving that breeding had occurred. The core of the Shippingport demonstration LWBR consisted of an array of seed and blanket modules surrounded by an outer reflector region. In the seed and blanket regions, the fuel pellets contained a mixture of thorium-232 oxide (ThO2) and uranium oxide (UO2) that was over 98% enriched in U-233. The proportion by weight of UO2 was around 5-6% in the seed region, and about 1.5-3% in the blanket region. The reflector region contained only thorium oxide at the beginning of the core life. U-233 was used because at the time it was believed that U-235 would not release enough neutrons per fission and Pu-239 would parasitically capture too many neutrons to allow breeding in a PWR. Current thorium fuel cycle researchSeveral advanced reactors concepts are currently being developed, including:
Radkowsky Thorium Reactor The work at Shippingport (see section above on the Light Water Breeder Reactor) was developed by Alvin Radkowsky, who was the chief scientist of the United States Navy’s nuclear propulsion programme from 1950 to 1972 and headed the team that built the Shippingport plant. The Radkowsky Thorium Reactor (RTR) addresses the aspects of the thorium fuel cycle that are considered sensitive from the point of view of weapons proliferation. In particular the RTR avoids the need to separate U-233. Radkowsky proposed the use of a heterogenous seed-blanket fuel assembly geometry, which separates the uranium (or plutonium) part of the fuel (the seed) from the thorium part of the fuel (the blanket). In the blanket part, U-233 is generated and fissioned, while the seed part supplies neutrons to the blanket. Either uranium enriched to 20% U-235 or plutonium can be used in the seed region3. One method of increasing the proliferation resistance of the design is to include some U-238 in the thorium blanket. Any uranium chemically separated from it (for the U-233 ) would not be useable for weapons. Used blanket fuel would also contain U-232, which decays rapidly and has very gamma-active daughters creating significant problems in handling the bred U-233 and hence conferring proliferation resistance. Plutonium produced in the seed will have a high proportion of Pu-238, generating a lot of heat and making it even more unsuitable for weapons than normal reactor-grade plutonium. Radkowsky’s designs are currently being developed by Thorium Power (now Lightbridge Corporation)d, based in McLean, Virginia. Since 1994, Thorium Power Ltd has been involved in a Russian programme to develop a thorium-uranium fuel, which more recently has moved to have a particular emphasis on utilization of weapons-grade plutonium in a thorium-plutonium fuel. The program is based at Moscow’s Kurchatov Institute and receives US government funding to design fuel for Russian VVER-1000 reactors. The design has a demountable centre portion and blanket arrangement, with the plutonium in the centre and the thorium (with uranium) around ite. The blanket material remains in the reactor for nine years but the centre portion is burned for only three years (as in a normal VVER). Design of the seed fuel rods in the centre portion draws on extensive experience of Russian navy reactors. The thorium-plutonium fuel claims four advantages over the use of mixed uranium-plutonium oxide (MOX) fuel: increased proliferation resistance; compatibility with existing reactors – which will need minimal modification to be able to burn it; the fuel can be made in existing plants in Russia; and a lot more plutonium can be put into a single fuel assembly than with MOX fuel, so that three times as much can be disposed of as when using MOX. The used fuel amounts to about half the volume of MOX and is even less likely to allow recovery of weapons-useable material than used MOX fuel, since less fissile plutonium remains in it. With an estimated 150 tonnes of surplus weapons plutonium in Russia, the thorium-plutonium project would not necessarily cut across existing plans to make MOX fuel. Liquid Fluoride Thorium Reactor A quite different concept is the Liquid Fluoride Thorium Reactor (LFTR), utilizing U-233 which has been bred in a liquid thorium salt blanket. The core consists of fissile U-233 tetrafluoride in molten fluoride salts of lithium and beryllium at some 700°C and at low pressure within a graphite structure that serves as a moderator and neutron reflector. Fission products dissolve in the salt and are removed progressively – xenon bubbles out, others are captured chemically. Actinides are less-readily formed than in fuel with atomic mass >235, and those that do form stay in the fuel until they are transmuted and eventually fissioned. The blanket contains a mixture of thorium tetrafluoride in a fluoride salt containing lithium and beryllium, made molten by the heat of the core. Newly-formed U-233 forms soluble uranium tetrafluoride (UF4), which is converted to gaseous uranium hexafluoride (UF6) by bubbling fluorine gas through the blanket solution (which does not chemically affect the less-reactive thorium tetrafluoride). Uranium hexafluoride comes out of solution, is captured, then is reduced back to soluble UF4 by hydrogen gas in a reduction column, and finally is directed to the core to serve as fissile fuel. The LFTR is not a fast reactor, but with some moderation by the graphite is epithermal (intermediate neutron speed). Safety is achieved with a freeze plug which if power is cut allows the fuel to drain into subcritical geometry in a catch basin. There is also a negative temperature coefficient of reactivity due to expansion of the fuel. The China Academy of Sciences in January 2011 launched an R&D program on LFTR, known there as the thorium-breeding molten-salt reactor (Th-MSR or TMSR), and claimed to have the world’s largest national effort on it, hoping to obtain full intellectual property rights on the technology. India’s plans for thorium cycleWith about six times more thorium than uranium, India has made utilization of thorium for large-scale energy production a major goal in its nuclear power programme, utilising a three-stage concept:
This Indian programme has moved from aiming to be sustained simply with thorium to one ‘driven’ with the addition of further fissile uranium and plutonium, to give greater efficiency. In 2009, despite the relaxation of trade restrictions on uranium, India reaffirmed its intention to proceed with developing the thorium cycle. Another option for the third stage, while continuing with the PHWR and FBR stages, is the use of subcritical accelerator driven systems. Thorium and accelerator driven systemsIn an accelerator driven system (ADS), high-energy neutrons are produced through the spallationf reaction of high-energy protons from an accelerator striking heavy target nuclei (lead, lead-bismuth or other material). These neutrons can be directed to a subcritical reactor containing thorium, where the neutrons breed U-233 and promote the fission of it. There is therefore the possibility of sustaining a fission reaction which can readily be turned off, and used either for power generation or destruction of actinides resulting from the U/Pu fuel cycle. The use of thorium instead of uranium reduces the quantity of actinides that are produced. (See also information page on Accelerator-Driven Nuclear Energy.) Developing a thorium-based fuel cycleDespite the thorium fuel cycle having a number of attractive features, development has always run into difficulties. The main attractive features are:
The problems include:
Much development work is still required before the thorium fuel cycle can be commercialised, and the effort required seems unlikely while (or where) abundant uranium is available. In this respect, recent international moves to bring India into the ambit of international trade might result in the country ceasing to persist with the thorium cycle, as it now has ready access to traded uranium and conventional reactor designs. Nevertheless, the thorium fuel cycle, with its potential for breeding fuel without the need for fast neutron reactors, holds considerable potential in the long-term. It is a significant factor in the long-term sustainability of nuclear energy. |
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Unclear On Nuclear? Try Thorium – Nuclear Energy Without The Side Effects
HomeInventor Inventor Spot 23 March 2011
If the current events in Japan have demonstrated one thing, it’s that nuclear energy in its current form is not safe. Put simply, if the Japanese can’t do it right with their impeccable approach to workmanship, then heaven help the rest of us.
But nuclear energy produces about 13,000 times the amount of energy per pound of fuel than coal, and considerably less waste. The only problem with the waste, of course, is that uranium and plutonium produce immeasurably more dangerous waste than coal, or oil, or natural gas, or any other energy source currently in widespread use: not only does it need to be stored safely for thousands of years (like that’s going to happen), but if it gets in the wrong hands, well, use your imagination.
With so many unknowns surrounding nuclear power – the impossibility of 100% safe operation; the unlikeliness of ensuring safe storage of nuclear waste across millennia; the probability of some of that waste ending up in the hands of terrorists or rogue states – you could justifiably be wondering why there are nearly 450 nuclear power stations operating around the world, with a further 65 under construction.
You could especially be wondering why, if you knew that a way to process a much safer form of nuclear energy has been available for nearly the last half a century. And then if you discovered that the source of this energy was four times more abundant than uranium (which contains all the plutonium), you could well be vigorously shaking and slapping your head simultaneously.
Don’t do it to yourself! Even if it is true that thorium possesses all these properties.
The primary advantage of thorium is probably safety. As reported recently in The Telegraph, thorium expert Kirk Sorensen claims that, “If it begins to overheat, a little plug melts and the salts drain into a pan. There is no need for computers, or the sort of electrical pumps that were crippled by the tsunami. The reactor saves itself. They operate at atmospheric pressure so you don’t have the sort of hydrogen explosions we’ve seen in Japan. One of these reactors would have come through the tsunami just fine. There would have been no radiation release.” This is largely because thorium is not fissile: it cannot sustain a nuclear chain reaction without a catalyst.
But that’s not all. Because thorium is lighter than uranium (which is lighter than plutonium), it doesn’t produce as many heavy, radioactive byproducts. It produces considerably less waste than its heavier cousins, and that is waste that only needs to be managed for 500 years – still a long time, but nowhere near the 10,000 years that some existing nuclear waste requires. That’s if you want to store it. Alternatively, you could add a bit of plutonium to the mix, and you’d burn it all up as part of the energy creation process. That’s right: handled properly, a thorium reactor produces no radioactive waste.
Oh, and thorium comes out of the ground as 100% thorium. It doesn’t need to be enriched, like uranium, which contains less than 1% fissionable material. So, while there is around four times as much thorium in the ground as uranium, there is closer to 6,000 times more usable thorium than usable uranium.
In the USA, which possesses the world’s largest thorium reserves, an experimental thorium reactor was built at the Oak Ridge National Laboratory in Tennessee back in the ’60s, operating for around five years before its funding was cut. Today, there is an operating thorium reactor in India, and plans for them in China, Russia and Norway.
Liquid Fluoride Thorium Reactor
A quite different concept is the Liquid Fluoride Thorium Reactor (LFTR), utilizing U-233 which has been bred in a liquid thorium salt blanket.
The core consists of fissile U-233 tetrafluoride in molten fluoride salts of lithium and beryllium at some 700°C and at low pressure within a graphite structure that serves as a moderator and neutron reflector. Fission products dissolve in the salt and are removed progressively – xenon bubbles out, others are captured chemically. Actinides are less-readily formed than in fuel with atomic mass >235, and those that do form stay in the fuel until they are transmuted and eventually fissioned.
The blanket contains a mixture of thorium tetrafluoride in a fluoride salt containing lithium and beryllium, made molten by the heat of the core. Newly-formed U-233 forms soluble uranium tetrafluoride (UF4), which is converted to gaseous uranium hexafluoride (UF6) by bubbling fluorine gas through the blanket solution (which does not chemically affect the less-reactive thorium tetrafluoride). Uranium hexafluoride comes out of solution, is captured, then is reduced back to soluble UF4 by hydrogen gas in a reduction column, and finally is directed to the core to serve as fissile fuel.
The LFTR is not a fast reactor, but with some moderation by the graphite is epithermal (intermediate neutron speed). Safety is achieved with a freeze plug which if power is cut allows the fuel to drain into subcritical geometry in a catch basin. There is also a negative temperature coefficient of reactivity due to expansion of the fuel.
The China Academy of Sciences in January 2011 launched an R&D program on LFTR, known there as the thorium-breeding molten-salt reactor (Th-MSR or TMSR), and claimed to have the world’s largest national effort on it, hoping to obtain full intellectual property rights on the technology.