[ad_1]
The tropical beaches of India are probably reminiscent of sun-drenched palm trees, hot curry fish and dreadlocks.
But they also keep a surprising secret .
Their sand is rich in ] chemical element considered a cleaner and safer alternative to conventional nuclear fuels.
The country was eager to exploit its some 300,000 to 850,000 tons of thorium, probably the reserves . Largest of the world, although progress has been slow.
But this effort is again attracting attention, while the renewed interest in technology .
In 2017, Dutch scientists launched the first experimental thorium reactor for decades, new companies are promoting technology in the West and China has committed last year to spend 3,300 million dollars to develop reactors that can operate in thorium.
Proponents of this technology explain that it promises a decarbonized energy with less hazardous waste a lower risk of collapse and more difficult to become in the weapons compared to the other. conventional nuclear energy.
However, rapid progress in renewable energies, expensive development, and questions about the safety and cleanliness of future plants, are signs that their commercialization route seems uncertain.
The search for thorium in India is based on unique historical and geographical conditions which gives it considerable momentum.
Some believe this fanciful research is unlikely to succeed, but the country's nuclear scientists are considering a long-term strategy for carbon-free energy security in a country whose population could reach . 1,700 million inhabitants in 2060
"We are a nation that is hungry for energy," says Srikumar Banerjee, former secretary of the Department of Energy and Energy. Atomic Energy of India (DAE). "We must rely on local raw materials to ensure the long-term sustainability of a country that will host a fifth of humanity."
Today, all commercial nuclear power plants operate with uranium a fact that is partly due to geopolitics.
The development of nuclear energy in the West was closely related to the development of atomic bombs and the uranium derived products are much easier to convert into weapons.
"At another time, a different decision could have been made and we would have taken the thorium route in the 1950s … but we are where we are," says Geoff Parks, a nuclear engineer at University of Cambridge. 19659009] uranium "clbad =" img-responsive "src =" https://c.files.bbci.co.uk/3FBC/production/_104061361_uranio.jpg "/>
The Strategy
The country's rare uranium deposits convinced the founding father of its nuclear program, Homi Bhabha, that any long-term strategy should exceed thorium, its fuel more abundant.
Thus was launched a three-step program that continues to be the central element of Indian nuclear energy policy.
Thorium does not undergo spontaneous fission . (The nucleus of an atom is divided and releases energy that can generate electricity), on the contrary , it decomposes very slowly by emitting alpha radiation that can not even penetrate human skin, You should not worry about tanning on beaches of thorium.
To convert thorium into nuclear fuel, it is necessary to badociate a fissile material such as plutonium which releases neutrons during fission.
] They are captured by the thorium atoms and converted into a fissile uranium isotope called U233. An isotope is a variant of an element with a different number of neutrons.
"Thorium is like wet wood ," says Ratan Kumar Sinha, who succeeded Banerjee as secretary of the DAE. He explains that wet wood is not good for lighting a fire, but once placed in an oven that burns dry wood, it can catch the spark.
The first two stages of India's strategy are therefore oriented. to convert its abundant thorium reserves into fissile material
In the first stage, conventional uranium-fueled reactors produce plutonium as a by-product. The next step combines this with more uranium in "fast-breeder" reactors, which generate more plutonium than they use.
This makes it possible to build more breeding reactors, and once the fleet is large enough, they are converted. the thorium in U233. The last step combines U233 with more thorium to power the "Autonomous Thermal Reactors ", which can be recharged using raw thorium.
Bhabha's vision proved to be a challenge .
The West's attention to uranium means that India has dug a lonely furrow . Its nuclear weapons program and its refusal to sign the Nuclear Non-Proliferation Treaty isolated it for decades from world trade in nuclear fuel and technologies.
The lifting of these barriers According to Sinha, the civil-nuclear agreement reached in 2008 between India and the United States should accelerate progress.
While the country developed pressurized heavy water reactors fueled with uranium in the 1970s, the second step was slow in coming.
An experimental breeding reactor which entered service in 1985, but still has not reached the 40 MW capacity for which it was designed.
The prototype of the 500 MW fast-breeder reactor (PFBR, for its sigl as in English), which will serve as a model for a future fleet should be put online this year, but the first official launch date was 2010.
In other words,
India will also have to accumulate operational experience before any expansion, says Banerjee, and it will take time to produce fuel necessary, about 10 years to double the plutonium needed for construction. another reactor.
The process is even longer for thorium, the plutonium will be used to build the network before moving to thorium conversion. The extraction of U233 from thorium also poses significant challenges, because another by-product of the fuel cycle is the U232, which emits highly radioactive gamma rays .
Researchers at the Bhabha Atomic Research Center (BARC) have experimentally demonstrated the process, but to do so on a large scale, installations with armor armored against strong radiation will have to be installed. and complex robotics to isolate workers.
The design of the first Indian reactor capable of burning thorium is complete: Advanced Heavy Water Reactor (AHWR). But its construction is not imminent and Sinha, who led the design, points out that it is not a plan for the third stage.
It will still need refills of fissile material and will be more focused on the fuel cycle experience and the demonstration of new features.
A third stage reactor could be an autonomous "thermal reproducer" requiring U233 and thorium to start, but can then be filled with natural thorium
. this reactor is still unknown but it is generally accepted that reactors using a mixture of molten salt as fuel and coolant are the most promising.
This is a concept sought by promoters in Western countries. China and the first research and development work is already underway in India
Even the Indian nuclear establishment admits that it is unlikely that the country will generate substantial energy from thorium by the 2050s.
Others are more optimistic . "Thorium has been the subject of discussion for 70 years and I think we will continue to talk about it in the future," said University professor MV Ramana. from British Columbia (Canada), who has written a book on India's nuclear policy.
According to Ramana, conventional nuclear energy is no longer economically convincing, so it is untenable to add the cost of developing reactors suitable for treating thorium and complex fuel .
They say that the benefits of thorium outweigh these costs, but Ramana feels that they exaggerate.
One frequently mentioned benefit is safety, since thorium reactors should be less likely to collapse; but Ramana says that it's not possible to predict possible failures before running large-scale models.
" Chernobyl and Fukushima etc., were all accidents that should not occur"
While the presence of U232 means that thorium residues are more dangerous in the short term, their isotopic mixture is less dangerous for longer periods, because of the amount and type of radiation that releases.
This means that it will probably be easier to manage and store in the long run, according to the engineer. Parks, but the benefits are marginal and possibly of limited relevance, as we have not yet found a convincing way to treat existing nuclear waste.
Perhaps the most compelling sale is the difficulty of turning it into a weapon, he adds. The U233 can be used to make atomic bombs, but its complex processing makes it less attractive.
However, none of these potential benefits actually drives the Indian program, says Ramamurti Rajaraman, a professor of physics at the university. Jawaharlal Nehru, New Delhi.
"It's partly an institutional pride ," he explains.
The nuclear establishment is reluctant to abandon a long-standing flagship program. But more importantly, Bhabha's argument about self-sufficiency has remained powerful, he added, especially after the period of nuclear isolation in the country.
India is trying to meet the growing demand for energy while it is taking off from the rest of the world. chronic dependence on coal .
Renewable energies are certainly part of the picture, Anil Kakodkar believes. which is part of the Indian Atomic Energy Commission. The country plans to reach 175 GW of installed renewable energy capacity by 2022.
It is the fourth in the world in terms of installed wind capacity and the fifth by means of solar energy.
But the sun and the winds are too intermittent to feed the whole country. "Nuclear power is the only option for large-scale non-fossil energy production," he said. "And in the case of India, it must be essentially thorium."
If self-sufficiency is necessary for energy security, it is the subject of discussion.
When Bhabha devised India's strategy, it was thought that global uranium deposits were smaller and a rapid nuclear expansion was to put pressure on supplies. But global nuclear capacity has declined since the 1990s and there is more uranium than previously believed.
William Nuttall, professor at the Open University, specialist in energy policies, understands how the historical perspective of India can make thorium attractive .
But there are few signs of an impending decline of uranium, so the world markets are a sustainable way to ensure energy security
It's also all indeed it was possible to "decarbonize" without resorting to nuclear energy. "Nuclear energy has attributes that make it beneficial for climate change and energy security, but its thesis is unclear," he said.
However, India does not put all its eggs in one basket. In addition to its ongoing work in the fields of wind and solar energy the government has approved the construction of 12 heavy water reactors that will add to the 22 in operation and the nine in construction.
He also studies reactor offers. designed abroad with Russia, France and the United States . But, given its progress to date, Parks believes that thorium makes sense as a long-term source of supply for India.
"They should be commended for having a plan and sticking to it," he adds.
Even Scientists Indian nuclear companies doubt prospects for thorium in developed countries. With little room for energy consumption and uranium-based technology, they have little incentive to take the risk of a change of direction, Kakodkar says.
The opportunity lies in the growth of energy consumption in the developing world Kakodkar believes that the abundance of thorium and the proliferation resistance make this element a promising supplier of carbon-free energy.
"If you really want to switch to carbon-free energy, I do not see how it could happen without nuclear energy and how nuclear energy can develop without thorium," he added. "Then someone has to take the initiative ."
YOU ARE INTERESTING
[ad_2]
Source link
