India's Thorium based nuclear power programme

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3. Radioactive waste lasts max 300 years instead of a million years.
Initially a Thorium reactor produces as much radioactivity as other nuclear reactors, since that is what generates the heat by converting mass to heat, but the decay products have a much shorter half-life. See the figure below.



4. Can deplete some of the existing radioactive waste and nuclear weapons stockpiles.
Thorenco LLC is developing a special reactor to purify spent nuclear fuel. This thorium converter reactor is designed to transmute and to "fission away" the heavy transuranic metals, the "nuclear waste" that the world's fleet of 441+ light water reactors produce in spent fuel. This waste is about 4-5% of the volume of the fuel rods. It is composed of neptunium, plutonium, americium and curium. These transuranic elements are radiotoxic for very long periods of time. Thorenco's technology fissions the plutonium and irradiates the transuranics causing the heavy metal elements to fission or to become lighter elements with much shorter decay periods. The thorium fuel cycle provides the neutrons as does the reactor grade plutonium. Nuclear power becomes more sustainable because the volume of the spent fuel from the uranium plutonium cycle is reduced by up to 95%. More importantly, the storage time for the residue from the recycled thorium fuel is materially reduced. This will have to be stored for less than 1% of the time needed for the storage of the untreated transuranics.
5. Produces Plutonium-238 needed for space exploration.
WASHINGTON — The U.S. Senate gave final passage to an energy and water spending bill Oct. 15 2009 that denies President Barack Obama's request for $30 million for the Department of Energy to restart production of plutonium-238 (pu-238) for NASA deep space missions.
The House of Representatives originally approved $10 million of Obama's pu-238 request for next year, but ultimately adopted the Senate's position before voting Oct. 1 to approve the conference report on the 2010 Energy-Water Appropriations bill (H.R. 3183). The bill now heads to Obama, who is expected to sign it.
NASA relies on pu-238 to power long-lasting spacecraft batteries that transform heat into electricity. With foreign and domestic supplies dwindling, NASA officials are worried the shortage will prevent the agency from sending spacecraft to the outer planets and other destinations where sunlight is scarce.
Thorium reactors produce PU-238 as a "free" byproduct.

6. Does not produce Plutonium239 and higher used in nuclear bombs.
The higher Plutonium isotopes are about as nasty as they get, and need expensive protection against terror attacks, and need to be stored for a very long time.
 
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7. Produces isotopes that helps cure certain cancers.
For decades, medical researchers have sought treatments for cancer. Now, Alpha Particle
Immunotherapy offers a promising treatment for many forms of cancer, and perhaps a cure.
Unfortunately, the most promising alpha-emitting medical isotopes, actinium-225 and its
daughter, bismuth-213, are not available in sufficient quantity to support current research, much
less therapeutic use. In fact, there are only three sources in the world that largely "milk" these
isotopes from less than 2 grams of thorium source material. Additional supplies were not
forthcoming.
Fortunately, scientists and engineers at Idaho National Laboratory identified 40-year-old reactor
fuel stored at the lab as a substantial untapped resource and developed Medical Actinium for
Therapeutic Treatment, or MATT, which consists of two innovative processes (MATT-CAR and
MATT-BAR) to recover this valuable medical isotope.
8. Earthquake safe.
Thorium reactors have a very simple and compact design where gravity is the only thing needed to stop the nuclear reaction. Conventional Nuclear reactors depend on external power to shut down after a SCRAM, where poison rods fall down to halt the reaction. The next figure shows the concept of a Thorium reactor.



The idea is to empty the fissile U-233 core through gravity alone. Since the fuel is already molten, it can run out like pig-iron into cooling heat exchangers with water supplied thru gravity alone.



As we can see the reactor hardened structure is compact, and can be completely earthquake and tsunami proof. What can be sheared off are the steam pipes and external power, but the shutdown can complete without additional power.

9. No risk for a meltdown, the fuel is already molten.
The fuel in a Thorium reactor is U-233 in the form of UraniumFluoride (UF4) salt that also contains Lithium and Beryllium, in its molten form it has a very low vapor pressure. The salt flows easily through the heat exchangers and the separators. The salt is very toxic, but it is completely sealed.

10. Very high negative temperature coefficient leading to a safe control.
This is another beauty of the molten salt design. The temperature coefficient is highly negative, leading to a safe design with simple and consistent feedback. What does that mean? It means that if temperature in the core rises, the efficiency of the reaction goes down, leading to less heat generated. There is no risk for a thermal runaway. In contrast, Chernobyl used graphite moderated Uranium , and it suffered a thermal runaway as the operators bypassed three safety circuits trying to capture the last remaining power during a normal shut-down. The reactor splat, the graphite caught fire and the rest is history. Five days later two nuclear installations in Sweden shut down their reactors due to excessive radiation, but it took a while before they could figure out what had happened. First then did the Soviets confess there had been an accident.

11. Atmospheric pressure operating conditions, no risk for explosions.

Materials subjected to high radiation tend to get brittle or soften up. Thorium reactors operate under atmospheric conditions so the choice of materials that can withstand both high temperatures and high radiation is much greater, leading to a superior and less expensive design. There is no high pressure gas buildup and the separation stage can be greatly simplified.
 
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more Reasons

Eleven more reasons to switch to Thorium as Nuclear fuel. � Len Bilen's Blog

12. Scales beautifully from small portable generators to full size power plants.
One of the first applications was as an airborne nuclear reactor.



Granted this was not a Thorium breeder reactor, but it proves nuclear reactors can be made lightweight. Thorium reactor can be made even lighter as long as they are not of the breeder type.

13. No need for evacuation zones, can be placed near urban areas.

Thorium reactors operate at atmospheric pressure and have a very high negative temperature coefficient, so there is no risk for a boil-over. They are easily made earthquake-safe since no pressure vessel is needed.

14. Rapid response to increased or decreased power demands
.
The increase in power output to increased power demand is faster than in coal-fired power plant.
All you have to do is increase the speed of flow in the core and it will respond with raised temperature.

15. Lessens the need for an expanded national grid.

The National Electric grid is at the breaking point. It needs to be expanded, but neighborhood resistance is building in many areas where they need an expansion the most. The grid is also sensitive to terrorism activities.

15. Lessens the need for an expanded national grid.
The National Electric grid is at the breaking point. It needs to be expanded, but neighborhood resistance is building in many areas where they need an expansion the most. The grid is also sensitive to terrorism activities.


As we can see the national grid is extensive, and under constant strain. A way to lessen the dependency on the national grid is to sprinkle it with many small to medium sized Thorium Nuclear Power generators. They can be placed on barges in rivers and along the coast, giving the grid maximum flexibility to respond in case of an emergency.

16. Russia has a Thorium program



This is a self-contained Thorium Nuclear Reactor on a barge. Coolant readily available. Hoist it a couple of cables and the town will have all the power it needs.

17. China is starting up a Thorium program.
The People's Republic of China has initiated a research and development project in thorium molten-salt reactor technology, it was announced in the Chinese Academy of Sciences (CAS) annual conference on Tuesday, January 25. An article in the Wenhui News followed on Wednesday. Chinese researchers also announced this development on the Energy from Thorium Discussion Forum.
Led by Dr. Jiang Mianheng, a graduate of Drexel University in electrical engineering, the thorium MSR efforts aims not only to develop the technology but to secure intellectual property rights to its implementation.
This may be one of the reasons that the Chinese have not joined the international Gen-IV effort for MSR development, since part of that involves technology exchange. Neither the US nor Russia have joined the MSR Gen-IV effort either.
A Chinese delegation led by Dr. Jiang travelled to Oak Ridge National Lab last fall to learn more about MSR technology and told lab leadership of their plans to develop a thorium-fueled MSR.The Chinese also recognize that a thorium-fueled MSR is best run with uranium-233 fuel, which inevitably contains impurities (uranium-232 and its decay products) that preclude its use in nuclear weapons. Operating an MSR on the "pure" fuel cycle of thorium and uranium-233 means that a breakeven conversion ratio can be achieved, and after being started on uranium-233, only thorium is required for indefinite operation and power generation.

18. India has an active Thorium program.

"¢ India has a flourishing and largely indigenous nuclear power program and expects to have 20,000 MWe nuclear capacity on line by 2020 and 63,000 MWe by 2032. It aims to supply 25% of electricity from nuclear power by 2050.
"¢ Because India is outside the Nuclear Non-Proliferation Treaty due to its weapons program, it was for 34 years largely excluded from trade in nuclear plant or materials, which has hampered its development of civil nuclear energy until 2009.
"¢ Due to these trade bans and lack of indigenous uranium, India has uniquely been developing a nuclear fuel cycle to exploit its reserves of thorium.
"¢ Now, foreign technology and fuel are expected to boost India's nuclear power plans considerably. All plants will have high indigenous engineering content.
"¢ India has a vision of becoming a world leader in nuclear technology due to its expertise in fast reactors and thorium fuel cycle.
"¢ India's Kakrapar-1 reactor is the world's first reactor which uses thorium rather than depleted uranium to achieve power flattening across the reactor core. India, which has about 25% of the world's thorium reserves, is developing a 300 MW prototype of a thorium-based Advanced Heavy Water Reactor (AHWR). The prototype is expected to be fully operational by 2011, following which five more reactors will be constructed. Considered to be a global leader in thorium-based fuel, India's new thorium reactor is a fast-breeder reactor and uses a plutonium core rather than an accelerator to produce neutrons. As accelerator-based systems can operate at sub-criticality they could be developed too, but that would require more research. India currently envisages meeting 30% of its electricity demand through thorium-based reactors by 2050.

19.Lawrence Livermore Laboratories is developing a small portable self-contained Thorium reactor capable of being carried on a low-bed trailer.
A Democratic member of the United States House of Congress (Joseph Sestak) in 2010 added funding for research and development for a reactor that could use thorium as fuel and fit on a destroyer-sized ship. Lawrence Livermore national laboratories are currently in the process of designing such a self-contained (3 meters by 15 meters) thorium reactor. Called SSTAR (Small, Sealed, Transportable, Autonomous Reactor), this next-generation reactor will produce 10 to 100 megawatts electric and can be safely transported via ship or truck. The first units are expected to arrive in 2015, be tamper resistant, passively failsafe and have a operative life of 30+ years.

 
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20. The need for a Yucca Mountain nuclear storage facility will eventually go away.
Since Thorium consumes the fissile material as it is getting created, the need for a long term storage facility of the Yucca Mountain type will eventually go away. In remote locations there can be built Thorium Nuclear Power generators that consume spent material from other nuclear processes. The need to do it in remote locations is the hazard of the already existing nuclear wastes. It should be possible to reduce the existing stockpile of nuclear wastes and nuclear bombs by about 90% and make electricity in the process. The cost to do this is higher than the normal process due to the additional cost of security.

21. Produces electricity at a cost of about 4 c/kWh.

The cost to produce electricity with Thorium generators should be about 40% less than Advanced Nuclear and about 30 % less than from Coal (with scrubbers). Solar generation is about 4 times more expensive (without subsidies) Wind power is cheaper when the wind blows, but the generation capacity has to be there even when the wind doesn't blow, so the only gain from wind power is to lessen the mining or extraction of carbon. Even if we double the renewable power we will only go from 3.6% to 7.2% of total energy needed. Hydroelectric power is for all practical purpose maxed out, so all future increase must come from Coal, Natural Gas, Petroleum or Nuclear.Thorium powered Nuclear Generators is the way to go.

22. Save $500 Million and use the 1600 Kg U-233 we have to start Thorium Reactors!

Here is an idea on how to save money that comes from the Thorium community on how to save more than 500 million dollars in the federal budget and energy, scientific and medical benefits as a bonus.The situation: The Department of Energy has 1400 Kg Uranium-233 stored at Oak Ridge National Lab. They are in process of downgrading it to natural uranium by downblending it with depleted uranium. They need 200 tons of depleted uranium to do the task, rendering it unusable for anything. The decommissioning was approved in 2003 and to date 130 million has been spent, but the actual downblending hasn't even started yet.

Proposal 1. Sell it to India which has an active Thorium nuclear reactor program. There it can be used as a fuel producing an estimated 600 million dollars worth of electricity. Sarah Palin is going to India to be the keynote speaker at the India Today Conclave, a good forum to publicize this and other potential cooperation in future of nuclear power generation.

Proposal 2. Stop the decommissioning immediately. Build our own Thorium Nuclear Reactor and over time get 600 million dollars worth of electric power and 45g of Plutonium-238.
 
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India committed to harnessing nuclear energy: PM - Hindustan Times

India committed to harnessing nuclear energy: PM

India on Sunday said it was committed to harness nuclear power and ensure highest levels of safety even as some countries have put their atomic energy plans under review after the Fukushima nuclear accident. In his annual 'Report to the People', Prime Minister Manmohan Singh underlined the committment to ensure highest levels of safety at nuclear installations and rolled out plans to strengthen the nuclear regulator by imparting it greater autonomy.

"We are committed to the highest levels of safety in the nuclear programme, and have initiated the process of strengthening the Atomic Energy Regulatory Board and making it an autonomous and independent regulatory authority," he said.

"The government is committed to harnessing nuclear energy for sustainable economic growth while ensuring the highest levels of safety of the nuclear power programme," the report said.

Some countries, including Germany and China had ordered a review of the nuclear programme in the wake of the Fukushima nuclear accident in Japan.

In the light of the nuclear accident in Fukushima in Japan, technical review teams for assessing safety systems of nuclear plants in India have been setup, the report said.

With the commissioning of the fourth unit of the Kaiga generating station in Karnataka in January, India now has 20 nuclear power reactors with a total installed nuclear power generating capacity of 4,780 MWe.

An additional 22,500 tonnes of additional uranium resources have been established in Andhra Pradesh, Rajasthan and Meghalaya taking the country's uranium resources to about 1,62,000 tonnes, the report said.

It said a new nuclear Power Reactor Fuel Reprocessing Plant (PREFRE-2) was dedicated to the nation in January at Bhabha Atomic Research Centre, Tarapur which has been designed to process spent fuel from 220 MW PHWRs.

Scientists have also achieved the successful closing of the fast reactor fuel cycle at the Compact Reprocessing facility for advanced fuels in lead cells at Kalpakkam.

The spent fuel subassembly from Fast Breeder Test Reactor was reprocessed and the fissile material was re-fabricated as fuel and loaded back into the reactor, it said.

The report noted that the Civil Liability for Nuclear Damage Act 2010 was passed in September last year which provides for prompt compensation to the victims of a nuclear accident.
 
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thorium propulsion - a knol by Charles Stevens

thorium propulsion

Thorium MaxFeLaser Propulsion System

Thorium MaxFeLaser Propulsion System
There's been another small spate of news articles in the past couple of weeks about Thorium, due to its safer and more environmentally friendly characteristics in comparison to Uranium.

LPS has made design advancements in the developmental research of Thorium as a controlled sub-critical nuclear fuel -- particularly Magnetic contained Accelerator Driven sub-critical laser based reaction systems.

LPS's Thorium lasers potential for use as a controlled sub-critical nuclear power source might one day make it suitable for space propulsion. LPS in visions a MaxFeLaser Jet propulsion system that could be used to power a single-stage spacecraft to travel directly from the Earth to the Moon or the stars. LPS MaxFeLaser power systems harnessed to spacecraft propulsion system, would result in unlimited launch vehicle size and payload lifting capacity? I'm imagining you could build a launch vehicle the size of a Supertanker or the Empire State Building, if you wanted to.

Putting this much higher energy density fuels to work would create a completely new flexibility in the design of aerospace craft. (Not just spacecraft, but even large high-speed heavy-lift aerial intercontinental cargo transports to service our global economy.)
 
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India Designs Thorium-Fueled Reactor for Export :: POWER Magazine

India Designs Thorium-Fueled Reactor for Export


While the global spotlight is fixed on India's massive coal-fired power capacity expansion, the country with meager uranium reserves has been pressing on with a unique long-term program that pushes for research and development of nuclear reactors using all three main fissionable materials: uranium-235, plutonium, and uranium-233. The three-pronged program, developed largely during the country's almost 30-year-long isolation from international nuclear trade, also factors in India's abundant reserves of thorium, which constitute 25% of the world's total reserves.

The program has made some major advancements, as Anil Kakodkar, chair of India's Atomic Energy Commission (IAC) told members at the International Atomic Energy Agency's (IAEA's) General Conference in Vienna this September. The nation has largely completed design of a 300-MW Advanced Heavy Water Reactor (AHWR), a unit that will be fueled by a mix of uranium-233 and plutonium — which will be converted from thorium by previously deployed and domestically designed fast breeder reactors. Construction on the first AHWR is scheduled to start in 2012 — though no site has yet been announced. Civil construction of the nation's first 500-MW prototype fast breeder reactor at Kalpakkam, Tamil Nadu, meanwhile, is under way, scheduled for completion in 2011.

And now the nation has also designed a special version of the AHWR (Figure 5), a 300-MW reactor that uses low-enriched uranium (LEU), replacing plutonium with uranium enriched to 19.75% U-235, the AEC head said. Kakodkar indicated that the vertical, pressure tube type, boiling light water – cooled, and heavy water – moderated AHWR-LEU was intended for export. "This version of the design also can meet the requirement of medium sized reactors, in countries with small grids while meeting the requirements of next generation systems," he said. "While we strongly advocate recycle option, AHWR-LEU would also compete very favourably even in once through mode of fuel cycle."

5. Packing a punch. India, a country that has devoted its nuclear research and development program to making use of its abundant thorium reserves, recently announced it had designed a special version of the Advanced Heavy Water Reactor (AHWR), which uses low-enriched uranium (LEU). According to a brochure distributed at a recent nuclear conference in Vienna, in comparison with modern light water reactors, the 300-MW AHWR-LEU would require about 13% less mined natural uranium for the same quantity of energy produced. The country has indicated that this reactor would be exported to nations with small grids. Courtesy: Bhabha Atomic Research Centre


Kakodkar did not say when the new AHWR variant would be commercially ready. Industry experts said, however, that the announcement was significant because it reaffirmed that India was committed to development of its thorium fuel cycle and that it was doing so with urgency, particularly because of climate change concerns. The matter should also be given weight in light of Indian Prime Minister Manmohan Singh's assertion on Sept. 29 that the nation could generate 470 GW of power by 2050 if it managed the three-stage program well. "This will sharply reduce our dependence on fossil fuels and will be a major contribution to global efforts to combat climate change," he reportedly said at an international conference on the peaceful uses of nuclear energy.
 

RPK

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Uranium mines in India

Mineweb.com - The world's premier mining and mining investment website Protest against uranium mines in India could unravel a $500bn nuclear plan - URANIUM | Mineweb


MUMBAI -

The state of Andhra Pradesh in India was poised to become a major uranium hub, contributing almost 25% of the nuclear fuel for India's future nuclear energy needs. However, Uranium Corporation of India's proposal to expand the production of uranium mining in Thumalapalle in Kadapa district in Andhra Pradesh has come under fire.
Members of the National Alliance for People's Movement have opposed the project and the permission granted to the company's expansion plans. Officials have said the uranium mining would be hazardous to the people living in the region.
It is not just this project. Across India, protests have been growing against old and new nuclear power plants. Nuclear power plants are proposed at Haripur in West Bengal, Mithi Virdi in Gujarat, Madban in Maharashtra, Chutka in Madhya Pradesh and Kadapa in Andhra Pradesh.
The country aims to produce 20,000 mw of nuclear power by the year 2020. Analysts have estimated its atomic energy market at $150-200 billion, predicted to rise to $500 billion if plans are implemented as targeted. The latest developments could however, put a paid to the plan.
Speaking about Andhra Pradesh, analysts said that Tummalapalle and adjoining areas in Super Basin in Kadapa are set to emerge as one of the major uranium provinces in the world, with almost a dozen new places with vast uranium resources being identified there.
It is estimated that as much as five hundred thousand tonnes of uranium resources can be extracted in the Super Basin in Kadapa. Moreover, uranium mineralisation in Vempalle extends over a 160 km belt from Maddimadugu to Chelumpalli, with the area turning into a potential zone for uranium exploitation. As many as 10 new blocks have been identified within a radius of 30 km around Tummalapalle, analysts have said.
However, protesters have noted that the local villagers in the region have been facing an acute shortage of ground water, with the district officials forbidding the digging of new borewells. Earlier, a section of the villagers of Peddamula village had stopped the ongoing reconnaissance survey of uranium deposits near Chitriyal village in Chandampet, in Andhra Pradesh.
Anti-uranium activists had also launched a protest walk earlier to mobilise public support against the Uranium Corporation of India's proposal to set up uranium mining and processing units at Peddagattu and Seripally..
A Human Rights Forum state official had flayed the government's insistence on going ahead with the project when local tribes expressed their opposition against it. ``Development should not be at the cost of people. Sustained development with people's involvement is the need the hour,'' he said.

In jeopardy

With India's annual domestic uranium production expected to double to about 800 tonnes by 2014 from mines in the eastern state of Jharkhand and the southern state of Andhra Pradesh, the opposition to the project has come as a severe setback.
India has been developing a new mine in Tummalapalle in Andhra Pradesh with reserves of 49,000 tonnes. According to a report tabled by the government, an additional 22,500 tonnes of additional uranium resources has been established in Andhra Pradesh, Rajasthan and Meghalaya taking the country's uranium resources to about 1,62,000 tonnes.
India's Prime Minister Manmohan Singh has also reaffirmed the country's commitment to harness nuclear energy for sustainable economic growth.
According to the World Nuclear Association, India has 20 reactors in operation, and four under construction. The country expects to have 20,000 MW of nuclear capacity by 2020 and 63,000 MW by 2032.
But opposition to many projects could well derail this. Take the case of the Jaitapur plant.
The 9,900 mw Jaitapur nuclear power plant, consisting of six nuclear reactors in Madban village, Ratnagiri district, in Maharashtra, was to be the world's largest nuclear power plant. French state owned nuclear engineering firm Areva and India's Nuclear Power Corporation of India had signed a $22-billion agreement in December 2010, to build six nuclear reactors in the presence of Nicolas Sarkozy, the French President.
However, in the wake of the nuclear tragedy at Fukushima in Japan, there has been severe opposition to the setting up of the French European Pressurised Reactors at the proposed Jaitapur nuclear facility, on the grounds that the reactors are of recent origin and therefore, unproven.
French Ambassador to India Jerome Bonnafont has been quoted by newswire agencies as saying that a conference has been scheduled for June 7, to discuss the matter among members of governments in charge of nuclear energy, to improve the safety systems and standards of atomic power plants.
This will be followed in August by the findings of the People's Tribunal on the Safety, Viability and Cost Efficiency of Nuclear Energy on the Jaitapur nuclear power project.

Shoring up

Over the next two decades, India has said it is aiming to increase its atomic energy generation capacity 13-fold. The country is in talks with Kazakhstan, Niger and Namibia to acquire uranium mines, even as talks are on with Canada for importing the reactor fuel.
Besides Tummalapalee, there are six mines in Jharkhand which produce 400 tonnes of uranium a year, along with the project at Lambapur in Andhra Pradesh and in Hubli, Karnataka. According to an official of the Uranium Corporation of India, huge uranium reserves have been identified at Lambapur-Peddagattu region in Nalgonda district of Andhra Pradesh.
Analysts tracking the sector have said that Indian companies have announced about $7 billion of overseas energy acquisitions since January 2010, as compared with $37 billion of bids by Chinese companies.
Opposition to several uranium projects within India could well ensure that India emerges as a buyer of uranium companies around the world, increasing competition for a limited number of assets.
 

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Preparations under way for hot run of Kudankulam nuclear reactor

Preparations under way for hot run of Kudankulam nuclear reactor

The Hindu : States / Tamil Nadu : Preparations under way for hot run of Kudankulam nuclear reactor

Things are getting set for the commissioning of the first unit of 1000 MWe of the Kudankulam Nuclear Power Project (KKNPP) in Tamil Nadu by the end of September or in October this year. Preparations are under way for the hot run of the reactor, an important activity that will take place before the reactor is loaded with the real fuel assemblies made of enriched uranium.

Pre-commissioning activities of the second reactor at the KKNPP, also of 1000 MWe capacity, have already started. It will reach criticality about nine months after the first reactor does so.

The two reactors are Russian ones that belong to the advanced design of VVER family but have been built by the Nuclear Power Corporation of India Limited (NPCIL). These are the biggest reactors to be built in India. They use enriched uranium as fuel, and light water as both coolant and moderator.

"The clearance for starting the hot run of the first unit is expected shortly. The hot run itself will start in some days," said M. Kasinath Balaji, Site Director, KKNPP. The hot run will continuously last about three weeks and it will be completed by the end of June. It will entail heating the primary coolant water to the reactor's operating temperature of 280 degrees Celsius. "We will be operating the reactor systems at the temperature at which the reactor will operate when it has real fuel bundles," he said.

Dummy fuel assemblies

The process of hot run will take place with the dummy fuel assemblies, which were loaded into the reactor several months ago. The dummy fuel assemblies have the same configuration as the real fuel assemblies but have no enriched uranium inside. The reactor vessel houses the 163 fuel assemblies inside.

Right now, the KKNPP engineers are preparing the reactor (the first unit) with the dummy fuel inside and the control rod drives installed, for conducting hydro tests at a pressure of 180 kg per sq. cm. as per the standard operating procedure. A hydro test done in December 2010 at 250 kg per sq. cm validated the strength of the reactor vessel and the primary coolant circuits. The control rod drives, which shut down the reactor in an emergency, were installed subsequently. The test at a pressure of 180 kg per sq. cm. will be done in a few days. After these tests are done, clearance for the hot run is expected.

"Hot run means taking the temperature of the primary coolant water to the operating temperature of 280 degrees Celsius with the help of energy from the primary coolant pumps," Mr. Balaji said. There are four primary coolant pumps, each requiring 6.3 MWe. During the hot run, three primary coolant pumps will be running and they will circulate the water through the dummy fuel assemblies. All safety systems will be tested.

Robotic inspection

After completion of the hot run, Mr. Balaji said, the reactor would be disassembled and the control rod drives removed. The cover of the reactor would be opened up and the dummy fuel assemblies inside the reactor vessel removed. Then the reactor vessel, the main coolant pipelines and all associated systems would be inspected for their integrity using highly sophisticated robotic machines. "These robotic machines have been tested in a mock-up facility and they are ready to carry out inspection operations inside the reactor once the hot run is completed. These inspection operations will last about a month," said Mr. Balaji.

The results of the hot run and inspection by the robotic machines will be reviewed by the Indian specialists along with their Russian counterparts.

After further review by the regulatory authorities, the KKNPP officials will make a request to the regulatory authorities for loading the real fuel assemblies into the reactor. The first fuel assemblies will be loaded in the beginning of September and after all the 163 fuel assemblies are loaded, the approach to its criticality will begin. The reactor will reach criticality by the end of September or the beginning of October. After a few weeks of low power experiments, electricity will be wheeled into the grid. Nine months later, the second unit will be started up.

From the two units with a total capacity of 2,000 MWe, Tamil Nadu's allocation will be 925 MWe, Karnataka 442 MWe, Kerala 266 MWe, Puducherry 67 MWe and the unallocated is 300 MWe.

Safety features

The Kudankulam reactors have state-of-the-art safety features in terms of the various passive safety systems backing the active safety systems. Twelve huge water tanks are installed inside the reactor building to ensure that the reactor is filled with water with boron in case of loss of water from the reactor fuel core. In addition, the reactor is cooled by way of natural circulation of air in the event of loss of electricity supply. Each reactor at Kudankulam is provided with four diesel generators of 6.3 MWe capacity each. Of the four diesel generators, only one is required to keep the reactor in a cool state under shutdown condition. The diesel generators were installed at a height of nine metres above the mean sea level, isolated from tsunami-like floods, Mr. Balaji said.

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Is it not dangerous, keeping all plants side by side at one place???
it could be a easy target for foes and ants too......
 

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Producing NPP equipment together | Russia & India Report


A Russian-Indian joint venture for the production of equipment for nuclear power plants (NPP) will be set up in India before the end of the year, Director General of the AtomEnergoMash Company Vladimir Kashchenko said on the sidelines of the International Atomexpo-2011 Forum that opened in Moscow.



In his words, the joint venture will be set by an Indian enterprise, which is ready to produce NPP equipment under Russia's technologies.



"Currently, India has got several enterprises of rather high technological market, which may become participants in the Russian-Indian joint venture," Kashchenko said.



"In addition, India is a very promising market of nuclear technological equipment for the entire Asian region," he stressed.



The AtomEnergoMash director general is confident that the joint venture of the kind is "the prototype for the setting up of a regional structure for the production of atomic technological equipment, which may be exported to other countries of the region."



"If the Asian market of nuclear technologies develops rather intensively, then the Russian-Indian joint ventures will be very interesting and promising project, which will be beneficial both for India and Russia," Kashchenko said.



In his words, "the project of the joint venture has always been coordinated in full. It is expected that the first supply contracts will be ready this year."



Touching upon the AtomEnergoMash's economy, Kashchenko said that this year's portfolio of orders is estimated at 80 billion roubles (USD 1 = RUB 27.77). as well as 50 percent of all orders are projects of the atomic industry.
 

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Kudankulam N-plant tsunami safe: Russian builder -  Business News - News - MSN India

Kudankulam N-plant tsunami safe: Russian builder

From Vinay Shukla
Moscow, Jun 8 (PTI) The Kudankulam nuclear power plant being built with assistance of a Russian company in Tamil Nadu is tsunami-safe and use of advanced technology rules out a Fukushima-type accident, a top Russian nuclear builder has said.

The plant is under the final stages of construction.

"Kudankulam with its protection system has withstood devastating tsunami in 2004, which caused massive destruction in neighbouring Sri Lanka and eastern coast of India," Alexander Glukhov, President of ''Atomstroieksport'' Corporation here said.

Talking to reporters on the sidelines of international AtomExpo-2011 congress of the world''s leading nuclear energy powers and consumers Glukhov categorically ruled out repetition of Fukushima type disaster at Kudankulam, built by his corporation.

"The safety system at Kudankulam is very reliable.
Even in case of cooling breakdown its reactors can withstand 30 hours, without meltdown," Glukhov underscored.

The two 1000 MW nuclear power reactors at the Kudankulam are scheduled to be functional by the end of this year.

The nuclear accident following a major earthquake and tsunami in March have raised worldwide concerns over atomic energy with some countries even contemplating a shift in their energy generation policy.

Germany and Switzerland have in fact announced plans and deadlines to end the use of nuclear energy.

India, however, has said it will continue to increase its dependence on atomic energy though it would ensure greater safeguards.
 

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India, Japan to restart talks on nuclear cooperation accord

The Hindu : News / National : India, Japan to restart talks on nuclear cooperation accord
PTI


India and Japan have agreed to restart talks on a bilateral nuclear cooperation agreement aimed at allowing Japanese companies to export atomic power technology and equipment to India.

External Affairs Minister S. M. Krishna and his Japanese counterpart Takeaki Matsumoto agreed on this during their talks on the sidelines of the Asia-Europe Meeting of Foreign Ministers in Hungary, Kyodo news agency reported.

Mr. Krishna and Mr. Matsumoto agreed to continue talks between the two countries, which started in June last year, for a nuclear cooperation agreement aimed at allowing Japan to export nuclear power technology and equipment, it said.

For Japan to formally enact a bilateral pact on a government-backed programme to transfer technology and equipment needed to build a nuclear power plant, an atomic cooperation accord needs to be cleared by Parliament.

While agreeing to enhance strategic dialogue on security and maritime safety issues, the ministers also agreed to accelerate working-level discussions on the Japan-India free trade agreement slated to take effect on August 1, the report said.
 
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IDN-InDepthNews | Analysis That Matters

India Makes Headway in Indigenous Atomic Power Programme


NEW DELHI (IDN) - The inauguration of India's latest nuclear reprocessing plant by Prime Minister Manmohan Singh on January 7, 2010 emphasizes once again the country's commitment to developing a largely indigenous atomic power programme.

The facility at Tarapur in the West Indian state of Maharashtra will break down highly radioactive used nuclear fuel to extract uranium and plutonium for reuse in fast neutron reactors. It comes as a welcome addition to several reprocessing plants in India -- all operated by the Bhabha Atomic Research Centre (BARC) -- at Tarapur, Trombay and Kalpakkam.

Small plants at each site were supplemented in 1998 by a new one of 100 tonnes per year at Kalpakkam, and this is now being extended so that it may handle carbide fuel from the Fast Breeder Test Reactor.

The new plant also has a capacity of 100 tonnes per year, and another entirely new facility is under construction at Kalpakkam.

BARC, named after Dr. Homi Bhabha, the country's pioneer in nuclear research, operates under the umbrella of the Government of India's Department of Atomic Energy.

"We have come a long way since the first reprocessing of spent fuel in India in 1964 at Trombay," said Prime Minister Singh at the inaugural ceremony attended by the country's senior nuclear scientists and engineers. "The recycling and optimal utilization of uranium is essential to meet our current and future energy security needs," he added.

Non-India sources confirm that India has a flourishing and largely indigenous nuclear power programme and expects to have 20,000 MWe (megawatt electricity) nuclear capacity on line by 2020 and 63,000 MWe by 2032. It aims to supply 25 percent of electricity from nuclear power by 2050.

"Because India is outside the Nuclear Non-Proliferation Treaty due to its weapons program, it was for 34 years largely excluded from trade in nuclear plant or materials, which has hampered its development of civil nuclear energy until 2009," says the World Nuclear Association (WNA) in its latest dossier on 'nuclear power in India'.

It adds: Due to these trade bans and lack of indigenous uranium, India has uniquely been developing a nuclear fuel cycle to exploit its reserves of thorium. Now, foreign technology and fuel are expected to boost India's nuclear power plans considerably. All plants will have high indigenous engineering content.

In fact, India has a vision of becoming a world leader in nuclear technology due to its expertise in fast reactors and thorium fuel cycle.

The backdrop to the country's ambitious nuclear power programme, says the London-based WNA, is that electricity demand in India is increasing rapidly, and the 830 billion kilowatt hours produced in 2008 was three times the 1990 output, though it still represented only some 700 kWh per capita for the year. With huge transmission losses, this resulted in only 591 billion kWh consumption.

"Coal provides 68% of the electricity at present, but reserves are limited. Gas provides 8%, hydro 14%. The per capita electricity consumption figure is expected to double by 2020, with 6.3% annual growth, and reach 5000-6000 kWh by 2050," the dossier informs.

Atomic power supplied 15.8 billion kWh (2.5%) of India's electricity in 2007 from 3.7 GWe (of 110 GWe total) capacity. After a dip in 2008-2009 this is expected to increase steadily as imported uranium becomes available and new plants come on line.

The forecast for the year ending March 2010 was 22 billion kWh. In 2010-2011 24 billion kWh is expected. For 2011-2012, 32 billion kWh is now forecast.

Nuclear experts say that India had achieved some 300 reactor-years of operation by mid 2009. "India's fuel situation, with shortage of fossil fuels, is driving the nuclear investment for electricity, and 25% nuclear contribution is foreseen by 2050, when 1094 GWe of base-load capacity is expected to be required. Almost as much investment in the grid system as in power plants is necessary," says the WNA.

India committed almost US$ 9 billion in 2006 for power projects, including 9.35 GWe of new generating capacity, taking forward projects to 43.6 GWe and US$ 51 billion. In late 2009 the government said it was confident that 62 GWe of new capacity would be added in the 5-year plan to March 2012, and best efforts were being made to add 12.5 GWe on top of this.

But only 18 GWe had been achieved by the mid point of October 2009, when 152 GWe was on line. The government's five-year-year plan for 2012-2017 was targeting the addition of 100 GWe over the period. Three quarters of this would be coal- or lignite-fired, and only 3.4 GWe nuclear, including two imported 1000 MWe units at one site and two indigenous 700 MWe units at another.

The U.S. audit, tax and advisory services firm KPMG said in a report in 2007 that India needed to spend US$ 120-150 billion on power infrastructure over the next five years, including transmission and distribution (T&D). It said that T&D losses were some 30-40%, amounting to worth more than $6 billion per year.

The target since about 2004 has been for nuclear power to provide 20 GWe by 2020, but in 2007 the Prime Minister referred to this as "modest" and capable of being "doubled with the opening up of international cooperation."

However, the World Nuclear Association says, that even the 20 GWe target will require substantial uranium imports. Late in 2008 NPCIL -- the Nuclear Power Corporation of India, a public sector enterprise under the administrative control of the Department of Atomic Energy -- projected 22 GWe on line by 2015, and the government was talking about having 50 GWe of nuclear power operating by 2050.

Then in June 2009 NPCIL said it aimed for 60 GWe nuclear by 2032, including 40 GWe of PWR capacity and 7 GWe of new PHWR capacity, all fuelled by imported uranium. This target was reiterated late in 2010.

The Atomic Energy Commission however expects some 500 GWe nuclear on line by 2060, and has since speculated that the amount might be higher still: 600-700 GWe by 2050, providing half of all electricity.

NUCLEAR POWER DEVELOPMENT

These projections are grounded in the fact that nuclear power for civil use is well established in India. Civil nuclear strategy has been directed towards complete independence in the nuclear fuel cycle, necessary because it is excluded from the 1970 Nuclear Non-Proliferation Treaty NPT due to it acquiring nuclear weapons capability after 1970.

Those five countries doing so before 1970 were accorded the status of Nuclear Weapons States under the NPT.

As a result, India's nuclear power programme has proceeded largely without fuel or technological assistance from other countries. Its power reactors to the mid 1990s had some of the world's lowest capacity factors, reflecting the technical difficulties of the country's isolation, but rose impressively from 60% in 1995 to 85% in 2001-2002. Then in 2008-10 the load factors dropped due to shortage of uranium fuel.

WNA says: India's nuclear energy self-sufficiency extended from uranium exploration and mining through fuel fabrication, heavy water production, reactor design and construction, to reprocessing and waste management.

The Atomic Energy Establishment was set up at Trombay, near Mumbai, in 1957 and renamed as Bhabha Atomic Research Centre ten years later. Plans for building the first Pressurised Heavy Water Reactor (PHWR) were finalised in 1964, and this prototype - Rajasthan-1, which had Canada's Douglas Point reactor as a reference unit, was built as a collaborative venture between Atomic Energy of Canada Ltd (AECL) and NPCIL. It started up in 1972 and was duplicated Subsequent indigenous PHWR development has been based on these units.
 
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Why thorium nuclear power shouldn't be written off | Environment | guardian.co.uk

Why thorium nuclear power shouldn't be written off

Climate change is a challenging topic for the green movement. Environmentalists can take the credit for being amongst the first to sound the alarm when the rest of the world chose to ignore the gloomy pronouncements being made by the scientific community.

However, the range of people now concerned about the threat we face has grown hugely in recent years and so too has the range of solutions being put forward. Not all of them have found favour with the green lobby. It is easy to find reasons to object to things but if we are going to successfully decarbonise the global economy then we cannot afford to rule out too many technologies before properly exploring and assessing their pros and cons.

It is tempting to think that all nuclear reactors are the same, and by extension, to place liquid-fluoride thorium reactors (LFTRs) in the same category as existing solid-fueled uranium and plutonium reactors.

However, just as it is possible to abhor nuclear weapons but support the use of radioactive isotopes in lifesaving medicine it is necessary to differentiate between different forms of nuclear power. Most of the problems currently associated with today's solid-uranium-fuelled reactors simply do not apply to LFTRs powered by thorium.

We worry about a "meltdown" in a solid-uranium reactor because it can lead to the release of radioactivity. But many features of a LFTR make it inherently safer. A liquid fuel is the normal mode of operation, which means the reactor can be designed to automatically drain itself into a walk-away safe configuration in the event of a problem.

A well-designed LFTR won't require emergency power or human intervention to shut down safely. The fluoride fuel form doesn't react with air and water and traps potentially dangerous elements like strontium and cesium as chemically-stable salts. LFTRs achieve high temperatures at normal pressure, unlike water-cooled reactors which require operating at high-pressures leading to safety concerns.

We are right to be concerned about the risk of military proliferation, but thorium was rejected early in the nuclear age because it is vastly more difficult to weaponise. There are 70,000 nuclear weapons in the world and none are based on thorium or its derivatives.

Another long-lasting concern is the waste generated in today's reactors because they use less than one per cent of the energy in their fuel and generate plutonium as a waste product. But a LFTR uses thorium and burns it up nearly completely.

Even the miniscule amount of waste has beneficial uses in medicine and exploration. The fluoride fuel used in a LFTR is impervious to radiation damage, allowing us to recycle the fuel into another reactor when the current one finishes its useful life. We can also use LFTRs to destroy existing stocks of separated plutonium rather than waiting tens of thousands of years for it to decay away. LFTRs can use up plutonium or highly-enriched uranium from decommissioned weapons to get the fission reaction started and thereafter run only on thorium.

Yet another problem is that today's reactors need to be built big and only produce one product—electricity. But LFTRs can be built small and they can be distributed geographically – even to generate combined heat and power. They can also be operated in a responsive and flexible manner – thus complementing rather than competing with intermittent renewables.

We worry about the environmental effects of mining and processing uranium. But thorium is far more abundant than uranium and is being mined already in the search for rare-earth minerals for renewable energy generators. Thus we don't need new mining for LFTRs—actually much less—and we can use thorium highly efficiently.

Despite the many potential benefits, as things stand, generating energy from thorium remains unproven although R&D projects are being pursued in France, China and India.

In the UK eight sites for potential new nuclear reactors have recently been announced. We are poised to go down the same road pursued by the Conservative Government in the 1980's when they announced a programme to build 10 new reactors.

In the end only one was built – late and massively over budget. But it cannot be denied that even that one station helped to reduce the UK's output of carbon dioxide from electricity generation. This fact has lead to a reversal in fortunes for the existing nuclear industry but the problems with uranium-based technologies have not gone away.

To successfully reduce the risk of climate change we need to commericalise affordable, safe, flexible, long-lasting, low carbon sources of energy. We do not know yet if LFTRs fit the bill but they look extremely promising. It would be irresponsible to dismiss them out of hand before finding out. If the UK is serious about pursuing nuclear power, and it appears that it is, then we must include the pursuit of thorium power in this endeavour. On paper it looks like it may just save us.
 
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Uranium Is So Last Century — Enter Thorium, the New Green Nuke | Magazine

Uranium Is So Last Century — Enter Thorium, the New Green Nuke

he thick hardbound volume was sitting on a shelf in a colleague's office when Kirk Sorensen spotted it. A rookie NASA engineer at the Marshall Space Flight Center, Sorensen was researching nuclear-powered propulsion, and the book's title — Fluid Fuel Reactors — jumped out at him. He picked it up and thumbed through it. Hours later, he was still reading, enchanted by the ideas but struggling with the arcane writing. "I took it home that night, but I didn't understand all the nuclear terminology," Sorensen says. He pored over it in the coming months, ultimately deciding that he held in his hands the key to the world's energy future.

Published in 1958 under the auspices of the Atomic Energy Commission as part of its Atoms for Peace program, Fluid Fuel Reactors is a book only an engineer could love: a dense, 978-page account of research conducted at Oak Ridge National Lab, most of it under former director Alvin Weinberg. What caught Sorensen's eye was the description of Weinberg's experiments producing nuclear power with an element called thorium.

At the time, in 2000, Sorensen was just 25, engaged to be married and thrilled to be employed at his first serious job as a real aerospace engineer. A devout Mormon with a linebacker's build and a marine's crew cut, Sorensen made an unlikely iconoclast. But the book inspired him to pursue an intense study of nuclear energy over the next few years, during which he became convinced that thorium could solve the nuclear power industry's most intractable problems. After it has been used as fuel for power plants, the element leaves behind minuscule amounts of waste. And that waste needs to be stored for only a few hundred years, not a few hundred thousand like other nuclear byproducts. Because it's so plentiful in nature, it's virtually inexhaustible. It's also one of only a few substances that acts as a thermal breeder, in theory creating enough new fuel as it breaks down to sustain a high-temperature chain reaction indefinitely. And it would be virtually impossible for the byproducts of a thorium reactor to be used by terrorists or anyone else to make nuclear weapons.

Weinberg and his men proved the efficacy of thorium reactors in hundreds of tests at Oak Ridge from the '50s through the early '70s. But thorium hit a dead end. Locked in a struggle with a nuclear- armed Soviet Union, the US government in the '60s chose to build uranium-fueled reactors — in part because they produce plutonium that can be refined into weapons-grade material. The course of the nuclear industry was set for the next four decades, and thorium power became one of the great what-if technologies of the 20th century.

Today, however, Sorensen spearheads a cadre of outsiders dedicated to sparking a thorium revival. When he's not at his day job as an aerospace engineer at Marshall Space Flight Center in Huntsville, Alabama — or wrapping up the master's in nuclear engineering he is soon to earn from the University of Tennessee — he runs a popular blog called Energy From Thorium. A community of engineers, amateur nuclear power geeks, and researchers has gathered around the site's forum, ardently discussing the future of thorium. The site even links to PDFs of the Oak Ridge archives, which Sorensen helped get scanned. Energy From Thorium has become a sort of open source project aimed at resurrecting long-lost energy technology using modern techniques.

And the online upstarts aren't alone. Industry players are looking into thorium, and governments from Dubai to Beijing are funding research. India is betting heavily on the element.

The concept of nuclear power without waste or proliferation has obvious political appeal in the US, as well. The threat of climate change has created an urgent demand for carbon-free electricity, and the 52,000 tons of spent, toxic material that has piled up around the country makes traditional nuclear power less attractive. President Obama and his energy secretary, Steven Chu, have expressed general support for a nuclear renaissance. Utilities are investigating several next-gen alternatives, including scaled-down conventional plants and "pebble bed" reactors, in which the nuclear fuel is inserted into small graphite balls in a way that reduces the risk of meltdown.

Those technologies are still based on uranium, however, and will be beset by the same problems that have dogged the nuclear industry since the 1960s. It is only thorium, Sorensen and his band of revolutionaries argue, that can move the country toward a new era of safe, clean, affordable energy.

Named for the Norse god of thunder, thorium is a lustrous silvery-white metal. It's only slightly radioactive; you could carry a lump of it in your pocket without harm. On the periodic table of elements, it's found in the bottom row, along with other dense, radioactive substances — including uranium and plutonium — known as actinides.

Actinides are dense because their nuclei contain large numbers of neutrons and protons. But it's the strange behavior of those nuclei that has long made actinides the stuff of wonder. At intervals that can vary from every millisecond to every hundred thousand years, actinides spin off particles and decay into more stable elements. And if you pack together enough of certain actinide atoms, their nuclei will erupt in a powerful release of energy.

To understand the magic and terror of those two processes working in concert, think of a game of pool played in 3-D. The nucleus of the atom is a group of balls, or particles, racked at the center. Shoot the cue ball — a stray neutron — and the cluster breaks apart, or fissions. Now imagine the same game played with trillions of racked nuclei. Balls propelled by the first collision crash into nearby clusters, which fly apart, their stray neutrons colliding with yet more clusters. Voilè0: a nuclear chain reaction.

Actinides are the only materials that split apart this way, and if the collisions are uncontrolled, you unleash hell: a nuclear explosion. But if you can control the conditions in which these reactions happen — by both controlling the number of stray neutrons and regulating the temperature, as is done in the core of a nuclear reactor — you get useful energy. Racks of these nuclei crash together, creating a hot glowing pile of radioactive material. If you pump water past the material, the water turns to steam, which can spin a turbine to make electricity.

Uranium is currently the actinide of choice for the industry, used (sometimes with a little plutonium) in 100 percent of the world's commercial reactors. But it's a problematic fuel. In most reactors, sustaining a chain reaction requires extremely rare uranium-235, which must be purified, or enriched, from far more common U-238. The reactors also leave behind plutonium-239, itself radioactive (and useful to technologically sophisticated organizations bent on making bombs). And conventional uranium-fueled reactors require lots of engineering, including neutron-absorbing control rods to damp the reaction and gargantuan pressurized vessels to move water through the reactor core. If something goes kerflooey, the surrounding countryside gets blanketed with radioactivity (think Chernobyl). Even if things go well, toxic waste is left over.

When he took over as head of Oak Ridge in 1955, Alvin Weinberg realized that thorium by itself could start to solve these problems. It's abundant — the US has at least 175,000 tons of the stuff — and doesn't require costly processing. It is also extraordinarily efficient as a nuclear fuel. As it decays in a reactor core, its byproducts produce more neutrons per collision than conventional fuel. The more neutrons per collision, the more energy generated, the less total fuel consumed, and the less radioactive nastiness left behind.

Even better, Weinberg realized that you could use thorium in an entirely new kind of reactor, one that would have zero risk of meltdown. The design is based on the lab's finding that thorium dissolves in hot liquid fluoride salts. This fission soup is poured into tubes in the core of the reactor, where the nuclear chain reaction — the billiard balls colliding — happens. The system makes the reactor self-regulating: When the soup gets too hot it expands and flows out of the tubes — slowing fission and eliminating the possibility of another Chernobyl. Any actinide can work in this method, but thorium is particularly well suited because it is so efficient at the high temperatures at which fission occurs in the soup.

In 1965, Weinberg and his team built a working reactor, one that suspended the byproducts of thorium in a molten salt bath, and he spent the rest of his 18-year tenure trying to make thorium the heart of the nation's atomic power effort. He failed. Uranium reactors had already been established, and Hyman Rickover, de facto head of the US nuclear program, wanted the plutonium from uranium-powered nuclear plants to make bombs. Increasingly shunted aside, Weinberg was finally forced out in 1973.

That proved to be "the most pivotal year in energy history," according to the US Energy Information Administration. It was the year the Arab states cut off oil supplies to the West, setting in motion the petroleum-fueled conflicts that roil the world to this day. The same year, the US nuclear industry signed contracts to build a record 41 nuke plants, all of which used uranium. And 1973 was the year that thorium R&D faded away — and with it the realistic prospect for a golden nuclear age when electricity would be too cheap to meter and clean, safe nuclear plants would dot the green countryside.

The thick hardbound volume was sitting on a shelf in a colleague's office when Kirk Sorensen spotted it. A rookie NASA engineer at the Marshall Space Flight Center, Sorensen was researching nuclear-powered propulsion, and the book's title — Fluid Fuel Reactors — jumped out at him. He picked it up and thumbed through it. Hours later, he was still reading, enchanted by the ideas but struggling with the arcane writing. "I took it home that night, but I didn't understand all the nuclear terminology," Sorensen says. He pored over it in the coming months, ultimately deciding that he held in his hands the key to the world's energy future.

Published in 1958 under the auspices of the Atomic Energy Commission as part of its Atoms for Peace program, Fluid Fuel Reactors is a book only an engineer could love: a dense, 978-page account of research conducted at Oak Ridge National Lab, most of it under former director Alvin Weinberg. What caught Sorensen's eye was the description of Weinberg's experiments producing nuclear power with an element called thorium.

At the time, in 2000, Sorensen was just 25, engaged to be married and thrilled to be employed at his first serious job as a real aerospace engineer. A devout Mormon with a linebacker's build and a marine's crew cut, Sorensen made an unlikely iconoclast. But the book inspired him to pursue an intense study of nuclear energy over the next few years, during which he became convinced that thorium could solve the nuclear power industry's most intractable problems. After it has been used as fuel for power plants, the element leaves behind minuscule amounts of waste. And that waste needs to be stored for only a few hundred years, not a few hundred thousand like other nuclear byproducts. Because it's so plentiful in nature, it's virtually inexhaustible. It's also one of only a few substances that acts as a thermal breeder, in theory creating enough new fuel as it breaks down to sustain a high-temperature chain reaction indefinitely. And it would be virtually impossible for the byproducts of a thorium reactor to be used by terrorists or anyone else to make nuclear weapons.

Weinberg and his men proved the efficacy of thorium reactors in hundreds of tests at Oak Ridge from the '50s through the early '70s. But thorium hit a dead end. Locked in a struggle with a nuclear- armed Soviet Union, the US government in the '60s chose to build uranium-fueled reactors — in part because they produce plutonium that can be refined into weapons-grade material. The course of the nuclear industry was set for the next four decades, and thorium power became one of the great what-if technologies of the 20th century.

Today, however, Sorensen spearheads a cadre of outsiders dedicated to sparking a thorium revival. When he's not at his day job as an aerospace engineer at Marshall Space Flight Center in Huntsville, Alabama — or wrapping up the master's in nuclear engineering he is soon to earn from the University of Tennessee — he runs a popular blog called Energy From Thorium. A community of engineers, amateur nuclear power geeks, and researchers has gathered around the site's forum, ardently discussing the future of thorium. The site even links to PDFs of the Oak Ridge archives, which Sorensen helped get scanned. Energy From Thorium has become a sort of open source project aimed at resurrecting long-lost energy technology using modern techniques.

And the online upstarts aren't alone. Industry players are looking into thorium, and governments from Dubai to Beijing are funding research. India is betting heavily on the element.

The concept of nuclear power without waste or proliferation has obvious political appeal in the US, as well. The threat of climate change has created an urgent demand for carbon-free electricity, and the 52,000 tons of spent, toxic material that has piled up around the country makes traditional nuclear power less attractive. President Obama and his energy secretary, Steven Chu, have expressed general support for a nuclear renaissance. Utilities are investigating several next-gen alternatives, including scaled-down conventional plants and "pebble bed" reactors, in which the nuclear fuel is inserted into small graphite balls in a way that reduces the risk of meltdown.

Those technologies are still based on uranium, however, and will be beset by the same problems that have dogged the nuclear industry since the 1960s. It is only thorium, Sorensen and his band of revolutionaries argue, that can move the country toward a new era of safe, clean, affordable energy.

Named for the Norse god of thunder, thorium is a lustrous silvery-white metal. It's only slightly radioactive; you could carry a lump of it in your pocket without harm. On the periodic table of elements, it's found in the bottom row, along with other dense, radioactive substances — including uranium and plutonium — known as actinides.

Actinides are dense because their nuclei contain large numbers of neutrons and protons. But it's the strange behavior of those nuclei that has long made actinides the stuff of wonder. At intervals that can vary from every millisecond to every hundred thousand years, actinides spin off particles and decay into more stable elements. And if you pack together enough of certain actinide atoms, their nuclei will erupt in a powerful release of energy.

To understand the magic and terror of those two processes working in concert, think of a game of pool played in 3-D. The nucleus of the atom is a group of balls, or particles, racked at the center. Shoot the cue ball — a stray neutron — and the cluster breaks apart, or fissions. Now imagine the same game played with trillions of racked nuclei. Balls propelled by the first collision crash into nearby clusters, which fly apart, their stray neutrons colliding with yet more clusters. Voilè0: a nuclear chain reaction.

Actinides are the only materials that split apart this way, and if the collisions are uncontrolled, you unleash hell: a nuclear explosion. But if you can control the conditions in which these reactions happen — by both controlling the number of stray neutrons and regulating the temperature, as is done in the core of a nuclear reactor — you get useful energy. Racks of these nuclei crash together, creating a hot glowing pile of radioactive material. If you pump water past the material, the water turns to steam, which can spin a turbine to make electricity.

Uranium is currently the actinide of choice for the industry, used (sometimes with a little plutonium) in 100 percent of the world's commercial reactors. But it's a problematic fuel. In most reactors, sustaining a chain reaction requires extremely rare uranium-235, which must be purified, or enriched, from far more common U-238. The reactors also leave behind plutonium-239, itself radioactive (and useful to technologically sophisticated organizations bent on making bombs). And conventional uranium-fueled reactors require lots of engineering, including neutron-absorbing control rods to damp the reaction and gargantuan pressurized vessels to move water through the reactor core. If something goes kerflooey, the surrounding countryside gets blanketed with radioactivity (think Chernobyl). Even if things go well, toxic waste is left over.

When he took over as head of Oak Ridge in 1955, Alvin Weinberg realized that thorium by itself could start to solve these problems. It's abundant — the US has at least 175,000 tons of the stuff — and doesn't require costly processing. It is also extraordinarily efficient as a nuclear fuel. As it decays in a reactor core, its byproducts produce more neutrons per collision than conventional fuel. The more neutrons per collision, the more energy generated, the less total fuel consumed, and the less radioactive nastiness left behind.

Even better, Weinberg realized that you could use thorium in an entirely new kind of reactor, one that would have zero risk of meltdown. The design is based on the lab's finding that thorium dissolves in hot liquid fluoride salts. This fission soup is poured into tubes in the core of the reactor, where the nuclear chain reaction — the billiard balls colliding — happens. The system makes the reactor self-regulating: When the soup gets too hot it expands and flows out of the tubes — slowing fission and eliminating the possibility of another Chernobyl. Any actinide can work in this method, but thorium is particularly well suited because it is so efficient at the high temperatures at which fission occurs in the soup.

In 1965, Weinberg and his team built a working reactor, one that suspended the byproducts of thorium in a molten salt bath, and he spent the rest of his 18-year tenure trying to make thorium the heart of the nation's atomic power effort. He failed. Uranium reactors had already been established, and Hyman Rickover, de facto head of the US nuclear program, wanted the plutonium from uranium-powered nuclear plants to make bombs. Increasingly shunted aside, Weinberg was finally forced out in 1973.

That proved to be "the most pivotal year in energy history," according to the US Energy Information Administration. It was the year the Arab states cut off oil supplies to the West, setting in motion the petroleum-fueled conflicts that roil the world to this day. The same year, the US nuclear industry signed contracts to build a record 41 nuke plants, all of which used uranium. And 1973 was the year that thorium R&D faded away — and with it the realistic prospect for a golden nuclear age when electricity would be too cheap to meter and clean, safe nuclear plants would dot the green countryside.
Illustrations: Martin Woodtli


The core of this hypothetical nuclear reactor is a cluster of tubes filled with a fluoride thorium solution. 1// compressor, 2// turbine, 3// 1,000 megawatt generator, 4// heat exchanger, 5// containment vessel, 6// reactor core.
Illustration: Martin Woodtli

When Sorensen and his pals began delving into this history, they discovered not only an alternative fuel but also the design for the alternative reactor. Using that template, the Energy From Thorium team helped produce a design for a new liquid fluoride thorium reactor, or LFTR (pronounced "lifter"), which, according to estimates by Sorensen and others, would be some 50 percent more efficient than today's light-water uranium reactors. If the US reactor fleet could be converted to LFTRs overnight, existing thorium reserves would power the US for a thousand years.

Overseas, the nuclear power establishment is getting the message. In France, which already generates more than 75 percent of its electricity from nuclear power, the Laboratoire de Physique Subatomique et de Cosmologie has been building models of variations of Weinberg's design for molten salt reactors to see if they can be made to work efficiently. The real action, though, is in India and China, both of which need to satisfy an immense and growing demand for electricity. The world's largest source of thorium, India, doesn't have any commercial thorium reactors yet. But it has announced plans to increase its nuclear power capacity: Nuclear energy now accounts for 9 percent of India's total energy; the government expects that by 2050 it will be 25 percent, with thorium generating a large part of that. China plans to build dozens of nuclear reactors in the coming decade, and it hosted a major thorium conference last October. The People's Republic recently ordered mineral refiners to reserve the thorium they produce so it can be used to generate nuclear power.

In the United States, the LFTR concept is gaining momentum, if more slowly. Sorensen and others promote it regularly at energy conferences. Renowned climatologist James Hansen specifically cited thorium as a potential fuel source in an "Open Letter to Obama" after the election. And legislators are acting, too. At least three thorium-related bills are making their way through the Capitol, including the Senate's Thorium Energy Independence and Security Act, cosponsored by Orrin Hatch of Utah and Harry Reid of Nevada, which would provide $250 million for research at the Department of Energy. "I don't know of anything more beneficial to the country, as far as environmentally sound power, than nuclear energy powered by thorium," Hatch says. (Both senators have long opposed nuclear waste dumps in their home states.)

Unfortunately, $250 million won't solve the problem. The best available estimates for building even one molten salt reactor run much higher than that. And there will need to be lots of startup capital if thorium is to become financially efficient enough to persuade nuclear power executives to scrap an installed base of conventional reactors. "What we have now works pretty well," says John Rowe, CEO of Exelon, a power company that owns the country's largest portfolio of nuclear reactors, "and it will for the foreseeable future."

Critics point out that thorium's biggest advantage — its high efficiency — actually presents challenges. Since the reaction is sustained for a very long time, the fuel needs special containers that are extremely durable and can stand up to corrosive salts. The combination of certain kinds of corrosion-resistant alloys and graphite could meet these requirements. But such a system has yet to be proven over decades.

And LFTRs face more than engineering problems; they've also got serious perception problems. To some nuclear engineers, a LFTR is a little "¦ unsettling. It's a chaotic system without any of the closely monitored control rods and cooling towers on which the nuclear industry stakes its claim to safety. A conventional reactor, on the other hand, is as tightly engineered as a jet fighter. And more important, Americans have come to regard anything that's in any way nuclear with profound skepticism.

So, if US utilities are unlikely to embrace a new generation of thorium reactors, a more viable strategy would be to put thorium into existing nuclear plants. In fact, work in that direction is starting to happen — thanks to a US company operating in Russia.

Located outside Moscow, the Kurchatov Institute is known as the Los Alamos of Russia. Much of the work on the Soviet nuclear arsenal took place here. In the late '80s, as the Soviet economy buckled, Kurchatov scientists found themselves wearing mittens to work in unheated laboratories. Then, in the mid-'90s, a savior appeared: a Virginia company called Thorium Power.



Founded by another Alvin — American nuclear physicist Alvin Radkowsky — Thorium Power, since renamed Lightbridge, is attempting to commercialize technology that will replace uranium with thorium in conventional reactors. From 1950 to 1972, Radkowsky headed the team that designed reactors to power Navy ships and submarines, and in 1977 Westinghouse opened a reactor he had drawn up — with a uranium thorium core. The reactor ran efficiently for five years until the experiment was ended. Radkowsky formed his company in 1992 with millions of dollars from the Initiative for Proliferation Prevention Program, essentially a federal make-work effort to keep those chilly former Soviet weapons scientists from joining another team.

The reactor design that Lightbridge created is known as seed-and-blanket. Its core consists of a seed of enriched uranium rods surrounded by a blanket of rods made of thorium oxide mixed with uranium oxide. This yields a safer, longer-lived reaction than uranium rods alone. It also produces less waste, and the little bit it does leave behind is unsuitable for use in weapons.

CEO Seth Grae thinks it's better business to convert existing reactors than it is to build new ones. "We're just trying to replace leaded fuel with unleaded," he says. "You don't have to replace engines or build new gas stations." Grae is speaking from Abu Dhabi, where he has multimillion-dollar contracts to advise the United Arab Emirates on its plans for nuclear power. In August 2009, Lightbridge signed a deal with the French firm Areva, the world's largest nuclear power producer, to investigate alternative nuclear fuel assemblies.

Until developing the consulting side of its business, Lightbridge struggled to build a convincing business model. Now, Grae says, the company has enough revenue to commercialize its seed-and-blanket system. It needs approval from the US Nuclear Regulatory Commission — which could be difficult given that the design was originally developed and tested in Russian reactors. Then there's the nontrivial matter of winning over American nuclear utilities. Seed-and-blanket doesn't just have to work — it has to deliver a significant economic edge.

For Sorensen, putting thorium into a conventional reactor is a half measure, like putting biofuel in a Hummer. But he acknowledges that the seed-and-blanket design has potential to get the country on its way to a greener, safer nuclear future. "The real enemy is coal," he says. "I want to fight it with LFTRs — which are like machine guns — instead of with light-water reactors, which are like bayonets. But when the enemy is spilling into the trench, you affix bayonets and go to work." The thorium battalion is small, but — as nuclear physics demonstrates — tiny forces can yield powerful effects.
 
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Thorium nuclear reactor « Hinducivilization

Thorium nuclear reactor

thoriumreactor.jpgThorium occurs in several minerals, the most common being the rare earth-thorium-phosphate mineral, monazite, which contains up to about 12% thorium oxide, but average 6-7%"¦

In India, both Kakrapar-1 and -2 units are loaded with 500 kg of thorium fuel in order to improve their operation when newly-started. Kakrapar-1 was the first reactor in the world to use thorium, rather than depleted uranium, to achieve power flattening across the reactor core. In 1995, Kakrapar-1 achieved about 300 days of full power operation and Kakrapar-2 about 100 days utilising thorium fuel. The use of thorium-based fuel was planned in Kaiga-1 and -2 and Rajasthan-3 and -4 (Rawatbhata) reactors.

With about six times more thorium than uranium, India has made utilisation of thorium for large-scale energy production a major goal in its nuclear power program, utilising a three-stage concept:

* Pressurised Heavy Water Reactors (PHWRs, elsewhere known as CANDUs) fuelled by natural uranium, plus light water reactors, produce plutonium.
* Fast Breeder Reactors (FBRs) use this plutonium-based fuel to breed U-233 from thorium. The blanket around the core will have uranium as well as thorium, so that further plutonium (ideally high-fissile Pu) is produced as well as the U-233. Then
* Advanced Heavy Water Reactors burn the U-233 and this plutonium with thorium, getting about 75% of their power from the thorium.

The spent fuel will then be reprocessed to recover fissile materials for recycling.

This Indian program 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.

http://www.uic.com.au/nip67.htm

Source:
Thorium

UIC Briefing Paper # 67

May 2007

* Thorium is much more abundant in nature than uranium.
* Thorium can also be used as a nuclear fuel through breeding to uranium-233 (U-233).
* When this thorium fuel cycle is used, much less plutonium and other transuranic elements are produced, compared with uranium fuel cycles.
* Several reactor concepts based on thorium fuel cycles are under consideration.

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 occurs in several minerals, the most common being the rare earth-thorium-phosphate mineral, monazite, which contains up to about 12% thorium oxide, but average 6-7%. There are substantial deposits in several countries (see table). Thorium-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.

World thorium resources
(economically extractable):
Country Reserves (tonnes)

Australia


300 000

India


290 000

Norway


170 000

USA


160 000

Canada


100 000

South Africa


35 000

Brazil


16 000

Other countries


95 000

World total


1 200 000

source: US Geological Survey, Mineral Commodity Summaries, January 1999 The 2005 IAEA-NEA "Red Book" gives a figure of 4.5 million tonnes of reserves and additional resources, but points out that this excludes data from much of the world. Geoscience Australia confirms the above 300,000 tonne figure for Australia, but stresses that this is based on assumptions, not direct geological data in the same way as most mineral rsources.

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.

Thorium as a nuclear fuel Thorium, as well as uranium, can be used as a nuclear fuel. Although not fissile itself, thorium-232 (Th-232) will absorb slow neutrons to produce uranium-233 (U-233), which is fissile. Hence like uranium-238 (U-238) it is fertile.

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-235 or Pu-239), a breeding cycle similar to but more efficient than that with U-238 and plutonium (in slow-neutron reactors) can be set up. The Th-232 absorbs a neutron to become Th-233 which normally decays to protactinium-233 and then U-233. 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.

Over the last 30 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, so some 40 times the amount of energy per unit mass might theoretically be available (withouit recourse to fast breeder reactors).

A major potential application for conventional PWRs involves fuel assemblies arranged so that a blanket of mainly thorium fuel rods surrounds a more-enriched seed element containing U-235 which supplies neutrons to the subcritical blanket. As U-233 is produced in the blanket it is burned there. This is the Light Water Breeder Reactor concept which was successfully demonstrated in the USA in the 1970s.

It is currently being developed in a more deliberately proliferation-resistant way. The central seed region of each fuel assembly will have uranium enriched to 20% U-235. The blanket will be thorium with some U-238, which means that any uranium chemically separated from it (for the U-233 ) is not useable for weapons. Spent blanket fuel also contains 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 Pu.

A variation of this is the use of whole homogeneous assembles arranged so that a set of them makes up a seed and blanket arrangement. If the seed fuel is metal uranium alloy instead of oxide, there is better heat conduction to cope with its higher temperatures. Seed fuel remains three years in the reactor, blanket fuel for up to 14 years.

Since the early 1990s Russia has had a program to develop a thorium-uranium fuel, which more recently has moved to have a particular emphasis on utilisation of weapons-grade plutonium in a thorium-plutonium fuel.

The program is based at Moscow's Kurchatov Institute and involves the US company Thorium Power and US government funding to design fuel for Russian VVER-1000 reactors. Whereas normal fuel uses enriched uranium oxide, the new design has a demountable centre portion and blanket arrangement, with the plutonium in the centre and the thorium (with uranium) around it*. The Th-232 becomes U-233, which is fissile – as is the core Pu-239. Blanket material remains in the reactor for 9 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.

*More precisely: A normal VVER-1000 fuel assembly has 331 rods each 9 mm diameter forming a hexagonal assembly 235 mm wide. Here, the centre portion of each assembly is 155 mm across and holds the seed material consisting of metallic Pu-Zr alloy (Pu is about 10% of alloy, and isotopically over 90% Pu-239) as 108 twisted tricorn-section rods 12.75 mm across with Zr-1%Nb cladding. The sub-critical blanket consists of U-Th oxide fuel pellets (1:9 U:Th, the U enriched up to almost 20%) in 228 Zr-1%Nb cladding tubes 8.4 mm diameter – four layers around the centre portion. The blanket material achieves 100 GWd/t burn-up. Together as one fuel assembly the seed and blanket have the same geometry as a normal VVER-100 fuel assembly.

The thorium-plutonium fuel claims four advantages over MOX: proliferation resistance, compatibility with existing reactors – which will need minimal modification to be able to burn it, and the fuel can be made in existing plants in Russia. In addition, a lot more plutonium can be put into a single fuel assembly than with MOX, so that three times as much can be disposed of as when using MOX. The spent fuel amounts to about half the volume of MOX and is even less likely to allow recovery of weapons-useable material than spent MOX fuel, since less fissile plutonium remains in it. With an estimated 150 tonnes of weapons Pu in Russia, the thorium-plutonium project would not necessarily cut across existing plans to make MOX fuel.

In 2007 Thorium Power formed an alliance with Red Star nuclear design bureau in Russia which will take forward the program to demonstrate the technology in lead-test fuel assemblies in full-sized commercial reactors.

R&D history The use of thorium-based fuel cycles has been studied for about 30 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 burnups 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:

* Between 1967 and 1988, the AVR experimental pebble bed reactor at Julich, Germany, operated for over 750 weeks at 15 MWe, about 95% of the time with thorium-based fuel. The fuel used consisted of about 100 000 billiard ball-sized fuel elements. Overall a total of 1360 kg of thorium was used, mixed with high-enriched uranium (HEU). Maximum burnups of 150,000 MWd/t were achieved.
* Thorium fuel elements with a 10:1 Th/U (HEU) ratio were irradiated in the 20 MWth Dragon reactor at Winfrith, UK, for 741 full power days. Dragon was run as an OECD/Euratom cooperation project, involving Austria, Denmark, Sweden, Norway and Switzerland in addition to the UK, from 1964 to 1973. The Th/U fuel was used to 'breed and feed', so that the U-233 formed replaced the U-235 at about the same rate, and fuel could be left in the reactor for about six years.
* General Atomics' Peach Bottom high-temperature, graphite-moderated, helium-cooled reactor (HTGR) in the USA operated between 1967 and 1974 at 110 MWth, using high-enriched uranium with thorium.
* In India, the Kamini 30 kWth experimental neutron-source research reactor using U-233, recovered from ThO2 fuel irradiated in another reactor, started up in 1996 near Kalpakkam. The reactor was built adjacent to the 40 MWt Fast Breeder Test Reactor, in which the ThO2 is irradiated.
* In the Netherlands, an aqueous homogenous suspension reactor has operated at 1MWth for three years. The HEU/Th fuel is circulated in solution and reprocessing occurs continuously to remove fission products, resulting in a high conversion rate to U-233.
* There have 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:

* The 300 MWe THTR reactor in Germany was developed from the AVR and operated between 1983 and 1989 with 674,000 pebbles, over half containing Th/HEU fuel (the rest graphite moderator and some neutron absorbers). These were continuously recycled on load and on average the fuel passed six times through the core. Fuel fabrication was on an industrial scale.
* The Fort St Vrain reactor was the only commercial thorium-fuelled nuclear plant in the USA, also developed from the AVR in Germany, and operated 1976 – 1989. It was a high-temperature (700°C), graphite-moderated, helium-cooled reactor with a Th/HEU fuel designed to operate at 842 MWth (330 MWe). The fuel was in microspheres of thorium carbide and Th/U-235 carbide coated with silicon oxide and pyrolytic carbon to retain fission products. It was arranged in hexagonal columns ('prisms') rather than as pebbles. Almost 25 tonnes of thorium was used in fuel for the reactor, and this achieved 170,000 MWd/t burn-up.
* Thorium-based fuel for Pressurised Water Reactors (PWRs) was investigated at the Shippingport reactor in the USA using both U-235 and plutonium as the initial fissile material. It was concluded that thorium would not significantly affect operating strategies or core margins. The light water breeder reactor (LWBR) concept was also successfully tested here from 1977 to 1982 with thorium and U-233 fuel clad with Zircaloy using the 'seed/blanket' concept.
* The 60 MWe Lingen Boiling Water Reactor (BWR) in Germany utilised Th/Pu-based fuel test elements.

India

In India, both Kakrapar-1 and -2 units are loaded with 500 kg of thorium fuel in order to improve their operation when newly-started. Kakrapar-1 was the first reactor in the world to use thorium, rather than depleted uranium, to achieve power flattening across the reactor core. In 1995, Kakrapar-1 achieved about 300 days of full power operation and Kakrapar-2 about 100 days utilising thorium fuel. The use of thorium-based fuel was planned in Kaiga-1 and -2 and Rajasthan-3 and -4 (Rawatbhata) reactors.

With about six times more thorium than uranium, India has made utilisation of thorium for large-scale energy production a major goal in its nuclear power program, utilising a three-stage concept:

* Pressurised Heavy Water Reactors (PHWRs, elsewhere known as CANDUs) fuelled by natural uranium, plus light water reactors, produce plutonium.
* Fast Breeder Reactors (FBRs) use this plutonium-based fuel to breed U-233 from thorium. The blanket around the core will have uranium as well as thorium, so that further plutonium (ideally high-fissile Pu) is produced as well as the U-233. Then
* Advanced Heavy Water Reactors burn the U-233 and this plutonium with thorium, getting about 75% of their power from the thorium.

The spent fuel will then be reprocessed to recover fissile materials for recycling.

This Indian program 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.

Another option for the third stage, while continuing with the PHWR and FBR programs, is the subcritical Accelerator-Driven Systems (ADS), – see below.

Emerging advanced reactor concepts Concepts for advanced reactors based on thorium-fuel cycles include:

* Light Water Reactors – With fuel based on plutonium oxide (PuO2), thorium oxide (ThO2) and/or uranium oxide (UO2) particles arranged in fuel rods.
* High-Temperature Gas-cooled Reactors (HTGR) of two kinds: pebble bed and with prismatic fuel elements.
Gas Turbine-Modular Helium Reactor (GT-MHR) – Research on HTGRs in the USA led to a concept using a prismatic fuel. The use of helium as a coolant at high temperature, and the relatively small power output per module (600 MWth), permit direct coupling of the MHR to a gas turbine (a Brayton cycle), resulting in generation at almost 50% thermal efficiency. The GT-MHR core can accommodate a wide range of fuel options, including HEU/Th, U-233/Th and Pu/Th. The use of HEU/Th fuel was demonstrated in the Fort St Vrain reactor (see above).
Pebble-Bed Modular reactor (PBMR) – Arising from German work the PBMR was conceived in South Africa and is now being developed by a multinational consortium. It can potentially use thorium in its fuel pebbles.
* Molten salt reactors – This is an advanced breeder concept, in which the fuel is circulated in molten salt, without any external coolant in the core. The primary circuit runs through a heat exchanger, which transfers the heat from fission to a secondary salt circuit for steam generation. It was studied in depth in the 1960s, but is now being revived because of the availability of advanced technology for the materials and components.
* Advanced Heavy Water Reactor (AHWR) – India is working on this, and like the Canadian CANDU-NG the 250 MWe design is light water cooled. The main part of the core is subcritical with Th/U-233 oxide, mixed so that the system is self-sustaining in U-233. A few seed regions with conventional MOX fuel will drive the reaction and give a negative void coefficient overall.
* CANDU-type reactors – AECL is researching the thorium fuel cycle application to enhanced CANDU-6 and ACR-1000 reactors. With 5% plutonium (reactor grade) plus thorium high burn-up and low power costs are indicated.
* Plutonium disposition – Today MOX (U,Pu) fuels are used in some conventional reactors, with Pu-239 providing the main fissile ingredient. An alternative is to use Th/Pu fuel, with plutonium being consumed and fissile U-233 bred. The remaining U-233 after separation could be used in a Th/U fuel cycle.

Use of thorium in Accelerator Driven Systems (ADS) In an ADS system, high-energy neutrons are produced through the spallation 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 means that less actinides are produced in the ADS itself. (see paper on Accelerator-Driven Nuclear Energy).

Developing a thorium-based fuel cycle Despite the thorium fuel cycle having a number of attractive features, development even on the scale of India's has always run into difficulties. Problems include:

* the high cost of fuel fabrication, due partly to the high radioactivity of U-233 chemically separated from the irradiated thorium fuel. Separated U-233 is always contaminated with traces of U-232 (69 year half life but whose daughter products such as thallium-208 are strong gamma emitters with very short half lives);
* the similar problems in recycling thorium itself due to highly radioactive Th-228 (an alpha emitter with 2 year half life) present;
* some weapons proliferation risk of U-233 (if it could be separated on its own); and
* the technical problems (not yet satisfactorily solved) in reprocessing.

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 international moves to bring India into the ambit of international trade will be critical. If India has ready access to traded uranium and conventional reactor designs, it may not persist with the thorium cycle.

Nevertheless, the thorium fuel cycle, with its potential for breeding fuel without the need for fast-neutron reactors, holds considerable potential long-term. It is a significant factor in the long-term sustainability of nuclear energy.

Sources:
Thorium based fuel options for the generation of electricity: Developments in the 1990s, IAEA-TECDOC-1155, International Atomic Energy Agency, May 2000.
The role of thorium in nuclear energy, Energy Information Administration/Uranium Industry Annual, 1996, p.ix-xvii.
Nuclear Chemical Engineering (2nd Ed.), Chapter 6: Thorium, M Benedict, T H Pigford and H W Levi, 1981, McGraw-Hill, p.283-317, ISBN: 0-07-004531-3.
See also: lead paper in Indian Nuclear Society 2001 conference proceedings, vol 2.
Kazimi M.S. 2003, Thorium Fuel for Nuclear Energy, American Scientist Sept-Oct 2003.
Morozov et al 2005, Thorium fuel as a superior approach to disposing of excess weapons-grade plutonium in Russian VVER-1000 reactors. Nuclear Future?
OECD NEA & IAEA, 2006, Uranium 2005: Resources, Production and Demand

http://www.uic.com.au/nip67.htm

Transcript, links and further information for 'Thorium Reactors'Narration Energy: it's something you normally don't think about. It pours in from the burning of coal, oil and gas, or from hydro-electric dams. And we keep needing more and more of it — but that means more greenhouse gases. Nuclear power doesn't generate any gases — but you try and say that in polite company. Wilson da Silva PTC It's not every day you hear about a potential solution to the energy problems of the 21st century in a cafe. But I did — from my friend Andrew. Dr Andrew Studer, Physicist Heard about a great new idea the other day; a thing called an energy amplifier. It's like a nuclear reactor driven by a particle accelerator. And the whole point is you can use thorium instead of uranium, and apparently this produces a heap less waste. The thing can never melt down or blow up. And you can actually use it to reprocess plutonium and nuclear waste from old bombs. Wilson da Silva Are we talking about a green nuclear reactor here? Dr Andrew Studer, Physicist Well, the whole thing is that it uses thorium which you can't do in an ordinary reactor. You don't have to have this particle accelerator driving it to make it work. Wilson da Silva And, what, you can turn it off if there's a risk of a meltdown? Dr Andrew Studer, Physicist Well, it can't meltdown because you are in complete control of how much energy's going into it in the first place. So there's no way the thing can ever overheat and blow up. Narration It sounds too good to be true, doesn't it? But there's a whole community of scientists out there working on this rather novel idea of a thorium reactor, otherwise known as an energy amplifier "¦ calculating, designing and experimenting. Three prototype reactors are to be built in Spain, and more are on the drawing boards. Wilson da Silva PTC It's sort of like a regular reactor, only it uses thorium instead. You know what we really need? We need to see how a regular nuclear reactor works. But it's not like we have that many of them in Australia. Wilson da Silva PTC I'm with Dr Sue Town who's a physicist here at the HIFAR reactor at Lucas Heights in Sydney. Dr Sue Town, physicist Looking in here you're basically looking at he top of the reactor, 25 uranium fuel elements that we have, various control arms and safety rods that we have, Wilson da Silva Ok, so those things in the middle are basically the fuel rods that drive the reactor? Dr Sue Town Yes"¦ we've got 25, they're Uranium 235 that have been enriched to 60%, the total weight is 280g per fuel element of Uranium 235 plus 238. Wilson da Silva And uranium is what powers most reactors around the world? Whether research reactors or power reactors? Dr Sue Town Right. Basically you have a neutron which bombards an Uranium 235 atom which splits the atom which gives rise to further neutrons coming out of the atom and that then produces fission. Wilson da Silva That's what causes criticality isn't it, when you get it to the point where there's a chain reaction occurring? Dr Sue Town Yes, that's what a reactor's all about, basically producing that and being able to control and maintain it "¦ Narration It's pretty easy really: just pack enough uranium together and a chain reaction occurs. That's criticality. Now this may be a research reactor, but power reactors work the same way: except that the superhot uranium core turns water instantly into steam, driving turbines and generating electricity — and lots of it. But they do have their drawbacks: they produce tonnes of radioactive waste that stays dangerous for a quarter of a million years. A byproduct is plutonium, which is great for making nuclear weapons. And there's always the chance, however remote, of a catastrophic meltdown. Wilson da Siva PTC Thorium is also radioactive, although not as much as uranium. No matter how much you pour into the core of a reactor, it can never go critical, or 'try to blow up'. So what you do is you heat it up. Not with a microwave oven, but with a particle accelerator. Basically a big particle gun which fires neutrons into the core of the thorium reactor — to the point where it is tickling criticality. The only Australian researching thorium reactors is Dr Reza Hashemi-Nezhad of High Energy Physics "¦ We're going to try to catch a physicist in is natural habitat "¦ (knock, knock). Wilson da Silva So what is this thing going to look like? Dr Reza Hashemi-Nezhad It's principle is very simple. It's made of a big container which is 30 metres deep. It contains a coolant vessel inside which is filled with the lead. We have the fuel here, which is made of thorium. And then this beam of the protons is fired through a tube into the middle of the fuel. And you produce a lot of neutrons, and produce "¦ nuclear fission and generate energy. Narration This is one reactor that ain't ever gonna meltdown. If it tries to overheat, you simply switch off the accelerator "¦ and the reaction just fizzles out. And it produces zero plutonium — so no bombs. The thorium core is so efficient it can even burn old plutonium, as well as nuclear waste, cooking the whole lot into oblivion. Dr Reza Hashemi-Nezhad This sub-critical nuclear reactor is the only logical way of burning the plutonium, producing energy, and getting rid of one of the most dangerous substances on the Earth. Wilson da Silva PTC Thorium reactors do produce some waste, but not much. (points to pile of toilet rolls) If this was the amount of waste produced by a conventional reactor, a thorium reactor would generate about this much. (pull one out, others collapse) Three per cent. The good news is, thorium waste is radioactive for only five hundred years. If you think that's long, try a quarter of a million. Narration That's how long conventional waste, on average, stays dangerous. But some of it is radioactive for 20 million years. In a small way, Dr Hashemi-Nezhad is contributing to the design of thorium reactors. He had these samples irradiated at a powerful accelerator in Moscow to try and predict how neutrons might behave in the core of the reactor. Dr Reza Hashemi-Nezhad This is a joint group: couple of teams from Russia, couple of teams from Germany; in Strasbourg, France; and China and India are involved in this project and are doing different bits of work. The final results will be compared with each other. When thorium reactors were first suggested in 1989, scientists just couldn't believe such a simple idea would work. As often happens in science, the discovery was always there to be made: it just took someone to see the possibility, and pounce on it. Dr Reza Hashemi-Nezhad If you look at it from any angle, it is much safer than existing reactors, and less harmful than even coal-burning power station. Narration There are plans for three reactors in Spain by 2005, while American scientists want to build them to incinerate weapons plutonium. If the science holds true, the first power reactors could be on-line within decades. And there's enough thorium in the ground to power the planet for another 4,400 centuries. Further Information· Dr Reza Hashemi Nezhad
 
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Thorium nuclear reactor « Hinducivilization

Thorium nuclear reactor

thoriumreactor.jpgThorium occurs in several minerals, the most common being the rare earth-thorium-phosphate mineral, monazite, which contains up to about 12% thorium oxide, but average 6-7%"¦

In India, both Kakrapar-1 and -2 units are loaded with 500 kg of thorium fuel in order to improve their operation when newly-started. Kakrapar-1 was the first reactor in the world to use thorium, rather than depleted uranium, to achieve power flattening across the reactor core. In 1995, Kakrapar-1 achieved about 300 days of full power operation and Kakrapar-2 about 100 days utilising thorium fuel. The use of thorium-based fuel was planned in Kaiga-1 and -2 and Rajasthan-3 and -4 (Rawatbhata) reactors.

With about six times more thorium than uranium, India has made utilisation of thorium for large-scale energy production a major goal in its nuclear power program, utilising a three-stage concept:

* Pressurised Heavy Water Reactors (PHWRs, elsewhere known as CANDUs) fuelled by natural uranium, plus light water reactors, produce plutonium.
* Fast Breeder Reactors (FBRs) use this plutonium-based fuel to breed U-233 from thorium. The blanket around the core will have uranium as well as thorium, so that further plutonium (ideally high-fissile Pu) is produced as well as the U-233. Then
* Advanced Heavy Water Reactors burn the U-233 and this plutonium with thorium, getting about 75% of their power from the thorium.

The spent fuel will then be reprocessed to recover fissile materials for recycling.

This Indian program 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.

http://www.uic.com.au/nip67.htm

Source:
Thorium

UIC Briefing Paper # 67

May 2007

* Thorium is much more abundant in nature than uranium.
* Thorium can also be used as a nuclear fuel through breeding to uranium-233 (U-233).
* When this thorium fuel cycle is used, much less plutonium and other transuranic elements are produced, compared with uranium fuel cycles.
* Several reactor concepts based on thorium fuel cycles are under consideration.

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 occurs in several minerals, the most common being the rare earth-thorium-phosphate mineral, monazite, which contains up to about 12% thorium oxide, but average 6-7%. There are substantial deposits in several countries (see table). Thorium-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.

World thorium resources
(economically extractable):
Country Reserves (tonnes)

Australia


300 000

India


290 000

Norway


170 000

USA


160 000

Canada


100 000

South Africa


35 000

Brazil


16 000

Other countries


95 000

World total


1 200 000

source: US Geological Survey, Mineral Commodity Summaries, January 1999 The 2005 IAEA-NEA "Red Book" gives a figure of 4.5 million tonnes of reserves and additional resources, but points out that this excludes data from much of the world. Geoscience Australia confirms the above 300,000 tonne figure for Australia, but stresses that this is based on assumptions, not direct geological data in the same way as most mineral rsources.

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.

Thorium as a nuclear fuel Thorium, as well as uranium, can be used as a nuclear fuel. Although not fissile itself, thorium-232 (Th-232) will absorb slow neutrons to produce uranium-233 (U-233), which is fissile. Hence like uranium-238 (U-238) it is fertile.

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-235 or Pu-239), a breeding cycle similar to but more efficient than that with U-238 and plutonium (in slow-neutron reactors) can be set up. The Th-232 absorbs a neutron to become Th-233 which normally decays to protactinium-233 and then U-233. 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.

Over the last 30 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, so some 40 times the amount of energy per unit mass might theoretically be available (withouit recourse to fast breeder reactors).

A major potential application for conventional PWRs involves fuel assemblies arranged so that a blanket of mainly thorium fuel rods surrounds a more-enriched seed element containing U-235 which supplies neutrons to the subcritical blanket. As U-233 is produced in the blanket it is burned there. This is the Light Water Breeder Reactor concept which was successfully demonstrated in the USA in the 1970s.

It is currently being developed in a more deliberately proliferation-resistant way. The central seed region of each fuel assembly will have uranium enriched to 20% U-235. The blanket will be thorium with some U-238, which means that any uranium chemically separated from it (for the U-233 ) is not useable for weapons. Spent blanket fuel also contains 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 Pu.

A variation of this is the use of whole homogeneous assembles arranged so that a set of them makes up a seed and blanket arrangement. If the seed fuel is metal uranium alloy instead of oxide, there is better heat conduction to cope with its higher temperatures. Seed fuel remains three years in the reactor, blanket fuel for up to 14 years.

Since the early 1990s Russia has had a program to develop a thorium-uranium fuel, which more recently has moved to have a particular emphasis on utilisation of weapons-grade plutonium in a thorium-plutonium fuel.

The program is based at Moscow's Kurchatov Institute and involves the US company Thorium Power and US government funding to design fuel for Russian VVER-1000 reactors. Whereas normal fuel uses enriched uranium oxide, the new design has a demountable centre portion and blanket arrangement, with the plutonium in the centre and the thorium (with uranium) around it*. The Th-232 becomes U-233, which is fissile – as is the core Pu-239. Blanket material remains in the reactor for 9 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.

*More precisely: A normal VVER-1000 fuel assembly has 331 rods each 9 mm diameter forming a hexagonal assembly 235 mm wide. Here, the centre portion of each assembly is 155 mm across and holds the seed material consisting of metallic Pu-Zr alloy (Pu is about 10% of alloy, and isotopically over 90% Pu-239) as 108 twisted tricorn-section rods 12.75 mm across with Zr-1%Nb cladding. The sub-critical blanket consists of U-Th oxide fuel pellets (1:9 U:Th, the U enriched up to almost 20%) in 228 Zr-1%Nb cladding tubes 8.4 mm diameter – four layers around the centre portion. The blanket material achieves 100 GWd/t burn-up. Together as one fuel assembly the seed and blanket have the same geometry as a normal VVER-100 fuel assembly.

The thorium-plutonium fuel claims four advantages over MOX: proliferation resistance, compatibility with existing reactors – which will need minimal modification to be able to burn it, and the fuel can be made in existing plants in Russia. In addition, a lot more plutonium can be put into a single fuel assembly than with MOX, so that three times as much can be disposed of as when using MOX. The spent fuel amounts to about half the volume of MOX and is even less likely to allow recovery of weapons-useable material than spent MOX fuel, since less fissile plutonium remains in it. With an estimated 150 tonnes of weapons Pu in Russia, the thorium-plutonium project would not necessarily cut across existing plans to make MOX fuel.

In 2007 Thorium Power formed an alliance with Red Star nuclear design bureau in Russia which will take forward the program to demonstrate the technology in lead-test fuel assemblies in full-sized commercial reactors.

R&D history The use of thorium-based fuel cycles has been studied for about 30 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 burnups 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:

* Between 1967 and 1988, the AVR experimental pebble bed reactor at Julich, Germany, operated for over 750 weeks at 15 MWe, about 95% of the time with thorium-based fuel. The fuel used consisted of about 100 000 billiard ball-sized fuel elements. Overall a total of 1360 kg of thorium was used, mixed with high-enriched uranium (HEU). Maximum burnups of 150,000 MWd/t were achieved.
* Thorium fuel elements with a 10:1 Th/U (HEU) ratio were irradiated in the 20 MWth Dragon reactor at Winfrith, UK, for 741 full power days. Dragon was run as an OECD/Euratom cooperation project, involving Austria, Denmark, Sweden, Norway and Switzerland in addition to the UK, from 1964 to 1973. The Th/U fuel was used to 'breed and feed', so that the U-233 formed replaced the U-235 at about the same rate, and fuel could be left in the reactor for about six years.
* General Atomics' Peach Bottom high-temperature, graphite-moderated, helium-cooled reactor (HTGR) in the USA operated between 1967 and 1974 at 110 MWth, using high-enriched uranium with thorium.
* In India, the Kamini 30 kWth experimental neutron-source research reactor using U-233, recovered from ThO2 fuel irradiated in another reactor, started up in 1996 near Kalpakkam. The reactor was built adjacent to the 40 MWt Fast Breeder Test Reactor, in which the ThO2 is irradiated.
* In the Netherlands, an aqueous homogenous suspension reactor has operated at 1MWth for three years. The HEU/Th fuel is circulated in solution and reprocessing occurs continuously to remove fission products, resulting in a high conversion rate to U-233.
* There have 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:

* The 300 MWe THTR reactor in Germany was developed from the AVR and operated between 1983 and 1989 with 674,000 pebbles, over half containing Th/HEU fuel (the rest graphite moderator and some neutron absorbers). These were continuously recycled on load and on average the fuel passed six times through the core. Fuel fabrication was on an industrial scale.
* The Fort St Vrain reactor was the only commercial thorium-fuelled nuclear plant in the USA, also developed from the AVR in Germany, and operated 1976 – 1989. It was a high-temperature (700°C), graphite-moderated, helium-cooled reactor with a Th/HEU fuel designed to operate at 842 MWth (330 MWe). The fuel was in microspheres of thorium carbide and Th/U-235 carbide coated with silicon oxide and pyrolytic carbon to retain fission products. It was arranged in hexagonal columns ('prisms') rather than as pebbles. Almost 25 tonnes of thorium was used in fuel for the reactor, and this achieved 170,000 MWd/t burn-up.
* Thorium-based fuel for Pressurised Water Reactors (PWRs) was investigated at the Shippingport reactor in the USA using both U-235 and plutonium as the initial fissile material. It was concluded that thorium would not significantly affect operating strategies or core margins. The light water breeder reactor (LWBR) concept was also successfully tested here from 1977 to 1982 with thorium and U-233 fuel clad with Zircaloy using the 'seed/blanket' concept.
* The 60 MWe Lingen Boiling Water Reactor (BWR) in Germany utilised Th/Pu-based fuel test elements.

India

In India, both Kakrapar-1 and -2 units are loaded with 500 kg of thorium fuel in order to improve their operation when newly-started. Kakrapar-1 was the first reactor in the world to use thorium, rather than depleted uranium, to achieve power flattening across the reactor core. In 1995, Kakrapar-1 achieved about 300 days of full power operation and Kakrapar-2 about 100 days utilising thorium fuel. The use of thorium-based fuel was planned in Kaiga-1 and -2 and Rajasthan-3 and -4 (Rawatbhata) reactors.

With about six times more thorium than uranium, India has made utilisation of thorium for large-scale energy production a major goal in its nuclear power program, utilising a three-stage concept:

* Pressurised Heavy Water Reactors (PHWRs, elsewhere known as CANDUs) fuelled by natural uranium, plus light water reactors, produce plutonium.
* Fast Breeder Reactors (FBRs) use this plutonium-based fuel to breed U-233 from thorium. The blanket around the core will have uranium as well as thorium, so that further plutonium (ideally high-fissile Pu) is produced as well as the U-233. Then
* Advanced Heavy Water Reactors burn the U-233 and this plutonium with thorium, getting about 75% of their power from the thorium.

The spent fuel will then be reprocessed to recover fissile materials for recycling.

This Indian program 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.

Another option for the third stage, while continuing with the PHWR and FBR programs, is the subcritical Accelerator-Driven Systems (ADS), – see below.

Emerging advanced reactor concepts Concepts for advanced reactors based on thorium-fuel cycles include:

* Light Water Reactors – With fuel based on plutonium oxide (PuO2), thorium oxide (ThO2) and/or uranium oxide (UO2) particles arranged in fuel rods.
* High-Temperature Gas-cooled Reactors (HTGR) of two kinds: pebble bed and with prismatic fuel elements.
Gas Turbine-Modular Helium Reactor (GT-MHR) – Research on HTGRs in the USA led to a concept using a prismatic fuel. The use of helium as a coolant at high temperature, and the relatively small power output per module (600 MWth), permit direct coupling of the MHR to a gas turbine (a Brayton cycle), resulting in generation at almost 50% thermal efficiency. The GT-MHR core can accommodate a wide range of fuel options, including HEU/Th, U-233/Th and Pu/Th. The use of HEU/Th fuel was demonstrated in the Fort St Vrain reactor (see above).
Pebble-Bed Modular reactor (PBMR) – Arising from German work the PBMR was conceived in South Africa and is now being developed by a multinational consortium. It can potentially use thorium in its fuel pebbles.
* Molten salt reactors – This is an advanced breeder concept, in which the fuel is circulated in molten salt, without any external coolant in the core. The primary circuit runs through a heat exchanger, which transfers the heat from fission to a secondary salt circuit for steam generation. It was studied in depth in the 1960s, but is now being revived because of the availability of advanced technology for the materials and components.
* Advanced Heavy Water Reactor (AHWR) – India is working on this, and like the Canadian CANDU-NG the 250 MWe design is light water cooled. The main part of the core is subcritical with Th/U-233 oxide, mixed so that the system is self-sustaining in U-233. A few seed regions with conventional MOX fuel will drive the reaction and give a negative void coefficient overall.
* CANDU-type reactors – AECL is researching the thorium fuel cycle application to enhanced CANDU-6 and ACR-1000 reactors. With 5% plutonium (reactor grade) plus thorium high burn-up and low power costs are indicated.
* Plutonium disposition – Today MOX (U,Pu) fuels are used in some conventional reactors, with Pu-239 providing the main fissile ingredient. An alternative is to use Th/Pu fuel, with plutonium being consumed and fissile U-233 bred. The remaining U-233 after separation could be used in a Th/U fuel cycle.

Use of thorium in Accelerator Driven Systems (ADS) In an ADS system, high-energy neutrons are produced through the spallation 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 means that less actinides are produced in the ADS itself. (see paper on Accelerator-Driven Nuclear Energy).

Developing a thorium-based fuel cycle Despite the thorium fuel cycle having a number of attractive features, development even on the scale of India's has always run into difficulties. Problems include:

* the high cost of fuel fabrication, due partly to the high radioactivity of U-233 chemically separated from the irradiated thorium fuel. Separated U-233 is always contaminated with traces of U-232 (69 year half life but whose daughter products such as thallium-208 are strong gamma emitters with very short half lives);
* the similar problems in recycling thorium itself due to highly radioactive Th-228 (an alpha emitter with 2 year half life) present;
* some weapons proliferation risk of U-233 (if it could be separated on its own); and
* the technical problems (not yet satisfactorily solved) in reprocessing.

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 international moves to bring India into the ambit of international trade will be critical. If India has ready access to traded uranium and conventional reactor designs, it may not persist with the thorium cycle.

Nevertheless, the thorium fuel cycle, with its potential for breeding fuel without the need for fast-neutron reactors, holds considerable potential long-term. It is a significant factor in the long-term sustainability of nuclear energy.

Sources:
Thorium based fuel options for the generation of electricity: Developments in the 1990s, IAEA-TECDOC-1155, International Atomic Energy Agency, May 2000.
The role of thorium in nuclear energy, Energy Information Administration/Uranium Industry Annual, 1996, p.ix-xvii.
Nuclear Chemical Engineering (2nd Ed.), Chapter 6: Thorium, M Benedict, T H Pigford and H W Levi, 1981, McGraw-Hill, p.283-317, ISBN: 0-07-004531-3.
See also: lead paper in Indian Nuclear Society 2001 conference proceedings, vol 2.
Kazimi M.S. 2003, Thorium Fuel for Nuclear Energy, American Scientist Sept-Oct 2003.
Morozov et al 2005, Thorium fuel as a superior approach to disposing of excess weapons-grade plutonium in Russian VVER-1000 reactors. Nuclear Future?
OECD NEA & IAEA, 2006, Uranium 2005: Resources, Production and Demand

http://www.uic.com.au/nip67.htm

Transcript, links and further information for 'Thorium Reactors'Narration Energy: it's something you normally don't think about. It pours in from the burning of coal, oil and gas, or from hydro-electric dams. And we keep needing more and more of it — but that means more greenhouse gases. Nuclear power doesn't generate any gases — but you try and say that in polite company. Wilson da Silva PTC It's not every day you hear about a potential solution to the energy problems of the 21st century in a cafe. But I did — from my friend Andrew. Dr Andrew Studer, Physicist Heard about a great new idea the other day; a thing called an energy amplifier. It's like a nuclear reactor driven by a particle accelerator. And the whole point is you can use thorium instead of uranium, and apparently this produces a heap less waste. The thing can never melt down or blow up. And you can actually use it to reprocess plutonium and nuclear waste from old bombs. Wilson da Silva Are we talking about a green nuclear reactor here? Dr Andrew Studer, Physicist Well, the whole thing is that it uses thorium which you can't do in an ordinary reactor. You don't have to have this particle accelerator driving it to make it work. Wilson da Silva And, what, you can turn it off if there's a risk of a meltdown? Dr Andrew Studer, Physicist Well, it can't meltdown because you are in complete control of how much energy's going into it in the first place. So there's no way the thing can ever overheat and blow up. Narration It sounds too good to be true, doesn't it? But there's a whole community of scientists out there working on this rather novel idea of a thorium reactor, otherwise known as an energy amplifier "¦ calculating, designing and experimenting. Three prototype reactors are to be built in Spain, and more are on the drawing boards. Wilson da Silva PTC It's sort of like a regular reactor, only it uses thorium instead. You know what we really need? We need to see how a regular nuclear reactor works. But it's not like we have that many of them in Australia. Wilson da Silva PTC I'm with Dr Sue Town who's a physicist here at the HIFAR reactor at Lucas Heights in Sydney. Dr Sue Town, physicist Looking in here you're basically looking at he top of the reactor, 25 uranium fuel elements that we have, various control arms and safety rods that we have, Wilson da Silva Ok, so those things in the middle are basically the fuel rods that drive the reactor? Dr Sue Town Yes"¦ we've got 25, they're Uranium 235 that have been enriched to 60%, the total weight is 280g per fuel element of Uranium 235 plus 238. Wilson da Silva And uranium is what powers most reactors around the world? Whether research reactors or power reactors? Dr Sue Town Right. Basically you have a neutron which bombards an Uranium 235 atom which splits the atom which gives rise to further neutrons coming out of the atom and that then produces fission. Wilson da Silva That's what causes criticality isn't it, when you get it to the point where there's a chain reaction occurring? Dr Sue Town Yes, that's what a reactor's all about, basically producing that and being able to control and maintain it "¦ Narration It's pretty easy really: just pack enough uranium together and a chain reaction occurs. That's criticality. Now this may be a research reactor, but power reactors work the same way: except that the superhot uranium core turns water instantly into steam, driving turbines and generating electricity — and lots of it. But they do have their drawbacks: they produce tonnes of radioactive waste that stays dangerous for a quarter of a million years. A byproduct is plutonium, which is great for making nuclear weapons. And there's always the chance, however remote, of a catastrophic meltdown. Wilson da Siva PTC Thorium is also radioactive, although not as much as uranium. No matter how much you pour into the core of a reactor, it can never go critical, or 'try to blow up'. So what you do is you heat it up. Not with a microwave oven, but with a particle accelerator. Basically a big particle gun which fires neutrons into the core of the thorium reactor — to the point where it is tickling criticality. The only Australian researching thorium reactors is Dr Reza Hashemi-Nezhad of High Energy Physics "¦ We're going to try to catch a physicist in is natural habitat "¦ (knock, knock). Wilson da Silva So what is this thing going to look like? Dr Reza Hashemi-Nezhad It's principle is very simple. It's made of a big container which is 30 metres deep. It contains a coolant vessel inside which is filled with the lead. We have the fuel here, which is made of thorium. And then this beam of the protons is fired through a tube into the middle of the fuel. And you produce a lot of neutrons, and produce "¦ nuclear fission and generate energy. Narration This is one reactor that ain't ever gonna meltdown. If it tries to overheat, you simply switch off the accelerator "¦ and the reaction just fizzles out. And it produces zero plutonium — so no bombs. The thorium core is so efficient it can even burn old plutonium, as well as nuclear waste, cooking the whole lot into oblivion. Dr Reza Hashemi-Nezhad This sub-critical nuclear reactor is the only logical way of burning the plutonium, producing energy, and getting rid of one of the most dangerous substances on the Earth. Wilson da Silva PTC Thorium reactors do produce some waste, but not much. (points to pile of toilet rolls) If this was the amount of waste produced by a conventional reactor, a thorium reactor would generate about this much. (pull one out, others collapse) Three per cent. The good news is, thorium waste is radioactive for only five hundred years. If you think that's long, try a quarter of a million. Narration That's how long conventional waste, on average, stays dangerous. But some of it is radioactive for 20 million years. In a small way, Dr Hashemi-Nezhad is contributing to the design of thorium reactors. He had these samples irradiated at a powerful accelerator in Moscow to try and predict how neutrons might behave in the core of the reactor. Dr Reza Hashemi-Nezhad This is a joint group: couple of teams from Russia, couple of teams from Germany; in Strasbourg, France; and China and India are involved in this project and are doing different bits of work. The final results will be compared with each other. When thorium reactors were first suggested in 1989, scientists just couldn't believe such a simple idea would work. As often happens in science, the discovery was always there to be made: it just took someone to see the possibility, and pounce on it. Dr Reza Hashemi-Nezhad If you look at it from any angle, it is much safer than existing reactors, and less harmful than even coal-burning power station. Narration There are plans for three reactors in Spain by 2005, while American scientists want to build them to incinerate weapons plutonium. If the science holds true, the first power reactors could be on-line within decades. And there's enough thorium in the ground to power the planet for another 4,400 centuries. Further Information· Dr Reza Hashemi Nezhad
 
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The Liquid Fluoride Thorium Reactor (LFTR), a Possible Contendor for Nuclear Propulsion Systems | Propulsiontech's Blog


The Liquid Fluoride Thorium Reactor (LFTR), a Possible Contendor for Nuclear Propulsion Systems


The Liquid Fluoride Thorium Reactors (LFTR) are purportedly safer (no harmful radioactive wastes produced), less expensive, smaller in size, does not use weapons-grade radioactive fuels and run on thorium-232, which is apparently an abundant heavy metal. The nuclear reactions in an LFTR can be started and stopped easily. The fuel does not have to be refined or enriched or made into pellet shapes. The reaction products are supposedly less harmful and have short half-lives.

Thus, I feel that the above qualities make LFTRs a potential fit for nuclear propulsion applications. LFTRs can be made smaller to fit an air/space vehicle. The controllability of the reactions gives us the ability to throttle power output on a vehicle. The reactors can be designed to withstand explosions. At present, aircraft black boxes are made tough and rugged, and designed to withstand crashes and submersion in water. So is the case with nuclear warheads on missiles. In the event of an explosion, the fuel is in such small quantities and the fission products are short-lived that there may not be the danger of contaminating radioactive fallout as is the case with Plutonium-239/241 or Uranium-235/238 reactors.

LFTRs could be used to power scramjets, since scramjets require massive amounts of energy to accelerate the working fluids to hypersonic speeds. But LFTRs could also find use in subsonic (bombers, freighters, fuel-tankers, etc.) and supersonic aircraft or even the single-stage-to-orbit (SSTO) aerospace planes.
 

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