Tag Archives: thorium

A New Page in History of Nuclear Energy?

A new page in the history of nuclear energy could be written this September 2021, in the middle of the Gobi Desert, in the north of China. At the end of August 2021, Beijing announced that it had completed the construction of its first thorium-fueled molten-salt nuclear reactor, with plans to begin the first tests of this alternative technology to current nuclear reactors within the next two weeks…

The Chinese reactor could be the first molten-salt reactor operating in the world since 1969, when the US abandoned its Oak Ridge National Laboratory facility in Tennessee. “Almost all current reactors use uranium as fuel and water, instead of molten salt and thorium,” which will be used in China’s new plant. These two “new” ingredients were not chosen by accident by Beijing: molten-salt reactors are among the most promising technologies for power plants

With molten-salt technology, “it is the salt itself that becomes the fuel”….The crystals are mixed with nuclear material – either uranium or thorium – heated to over 500°C to become liquid, and are then be able to transport the heat and energy produced. Theoretically, this process would make the installations safer. “Some accident risks are supposedly eliminated because liquid burning avoids situations where the nuclear reaction can get out of control and damage the reactor structures.”

There’s another advantage for China: this type of reactor does not need to be built near watercourses, since the molten salts themselves “serve as a coolant, unlike conventional uranium power plants that need huge amounts of water to cool their reactors”.  As a result, the reactors can be installed in isolated and arid regions… like the Gobi Desert.

Thorium belongs to a famous family of rare-earth metals that are much more abundant in China than elsewhere; this is the icing on the cake for Chinese authorities, who could increase its energy independence from major uranium exporting countries, such as Canada and Australia, two countries whose diplomatic relations with China have collapsed in recent years.

According to supporters of thorium, it would also a “greener” solution. Unlike the uranium currently used in nuclear power plants, burning thorium does not create plutonium, a highly toxic chemical element…

Among the three main candidates for nuclear reaction – uranium 235, uranium 238 and thorium – the first is “the only isotope naturally fissile”, Sylvain David explained. The other two must be bombarded with neutrons for the material to become fissile (able to undergo nuclear fission) and be used by a reactor: a possible but more complex process. Once that is done on thorium, it produces uranium 233, the fissile material needed for nuclear power generation….”This is an isotope that does not exist in nature and that can be used to build an atomic bomb,” pointed out Francesco D’Auria.

Excerpts from Why China is developing a game-changing thorium-fueled nuclear reactor, France24, Sept. 12, 2021

Thorium Reactors are Less Radioactive

Existing  nuclear reactors use uranium or plutonium—the stuff of bombs.  Thorium, though, is hard to turn into a bomb; not impossible, but sufficiently uninviting a prospect that America axed thorium research in the 1970s. It is also three or four times as abundant as uranium. In a world where nuclear energy was a primary goal of research, rather than a military spin-off, it would certainly look worthy of investigation. And it is, indeed, being investigated.

India has abundant thorium reserves, and the country’s nuclear-power programme, which is intended, eventually, to supply a quarter of the country’s electricity (up from 3% at the moment), plans to use these for fuel. This will take time. The Indira Gandhi Centre for Atomic Research already runs a small research reactor in Kalpakkam, Tamil Nadu, and the Bhabha Atomic Research Centre in Mumbai plans to follow this up with a thorium-powered heavy-water reactor that will, it hopes, be ready early next decade.

China’s thorium programme looks bigger. The Chinese Academy of Sciences claims the country now has “the world’s largest national effort on thorium”, employing a team of 430 scientists and engineers, a number planned to rise to 750 by 2015. This team, moreover, is headed by Jiang Mianheng, an engineering graduate of Drexel University in the United States who is the son of China’s former leader, Jiang Zemin (himself an engineer). Some may question whether Mr Jiang got his job strictly on merit. His appointment, though, does suggest the project has political clout. The team plan to fire up a prototype thorium reactor in 2015. Like India’s, this will use solid fuel. But by 2017 the Shanghai Institute of Applied Physics expects to have one that uses a trickier but better fuel, molten thorium fluoride…

One of the cleverest things about (Liquid Fluoride Thorium Reactors) LFTRs is that they work at atmospheric pressure. This changes the economics of nuclear power. In a light-water reactor, the type most commonly deployed at the moment, the cooling water is under extremely high pressure. As a consequence, light-water reactors need to be sheathed in steel pressure vessels and housed in fortress-like containment buildings in case their cooling systems fail and radioactive steam is released. An LFTR needs none of these.

Thorium is also easier to prepare than its rivals… By contrast thorium, once extracted from its ore, is reactor-ready…[T]horium reactors can run non-stop for years, unlike light-water reactors. These have to be shut down every 18 months to replace batches of fuel rods.  Thorium has other advantages, too. Even the waste products of LFTRs are less hazardous than those of a light-water reactor. There is less than a hundredth of the quantity and its radioactivity falls to safe levels within centuries, instead of the tens of millennia for light-water waste.

Paradoxically, though, given thorium’s history, it is the difficulty of weaponising thorium which many see (as it were) as its killer app in civil power stations. One or two 233U bombs were tested in the Nevada desert during the 1950s and, perhaps ominously, another was detonated by India in the late 1990s. But if the American experience is anything to go by, such bombs are temperamental and susceptible to premature detonation because the intense gamma radiation 233U produces fries the triggering circuitry and makes handling the weapons hazardous. The American effort was abandoned after the Nevada tests….. Rogue nations interested in an atom bomb are thus likely to leave thorium reactors well alone when there is so much poorly policed plutonium scattered around the world. So a technology abandoned because it could not be turned into weapons may now, in part for that very reason, be about to resurface.

Excerpts from Thorium reactors: Asgard’s fire, Economist,  April 12, at 78