Nuclear energy may have hit a rough patch here in the United States but at least overseas and especially in Asia, it is revving up and preparing to go faster than ever before. What’s less known, however, is just what type of nuclear reactors for which China has plans: molten salt reactors that run on thorium.
On the periodic table, thorium rests just two spots away from uranium, which is the prevailing fuel used by today’s nuclear reactors. Once uranium is used as a fuel, it becomes highly radioactive. That waste is then cooled in spent fuel pools before is stored in above-ground, concrete-encased steel caskets. As the world learned from Japan’s Fukushima nuclear accident, that radioactive material could escape and do a lot of potential harm.
Thorium, on the other hand, is also abundant in nature and can also be used to generate nuclear energy. But its proponents are saying that “molten salt reactors” that burn such fuels won’t “meltdown” because, unlike today’s high-pressured units, they are low-pressured and won’t vaporize. When used as a nuclear fuel, the whole cycle also produces less radioactive waste than does uranium.
China has the most aggressive research program into molten salt reactors and thorium. They are referred to as fourth generation nuclear reactors, which it hopes to commercialize in 15 years. If it is able to do so, experts say that nuclear energy would be more efficient, cheaper and safer than today’s uranium-based reactors. India and Canada are also pursuing the technology.
“In 2012, I visited the Chinese molten salt reactor labs near Shanghai and it was clear that they are taking the time to get the basics right and to build a strong program from the ground up,” says David Martin, deputy director of research for the Weinberg Foundation in London, in a series of emailed questions.
In total, China has 34 nuclear plants, says the World Nuclear Association, and 20 more are under construction. By 2020, nuclear energy will make up 58,000 megawatts of the country’s energy mix. By 2030, it is expected to be 150,000 megawatts of third-generation reactors. That is still much less than the country’s coal portfolio, which comprises about 70 percent of its electricity generation.
The US still relies on second-generation light-water, solid-fuel reactors that operate, on average, at more than 90 percent capacity. Georgia-based Southern Company and South Carolina-based Scana Corp. are building third-generation light-water reactors that are more efficient and even safer.
Thorium is most suited to run in fourth-generation molten salt reactors, which operate at lower pressures and which many consider to be fail-proof. Such reactors must reach high level temperatures to melt a salt solid. That liquid and fuel mixture is then used as a coolant in the fuel cycle.
“All fourth generation reactors make much less waste and run at higher temperatures,” says John Kutsch, executive director of the Thorium Energy Alliance in Chicago, who previously spoke with this writer. “But the similarity ends there. Inherently, thorium is much more abundant and easier to handle.”
The US, however, will find it difficult to transition to thorium because of its cold-war decision to invest in uranium fuels, which could be more easily enriched to make nuclear bombs. Even if there is a breakthrough in thorium technology, it would be too costly to retrofit America’s existing nuclear energy infrastructure. The supply chain is now fully stocked and includes everything from uranium suppliers to reactor designers.
The reality is that solid fuel reactors using uranium are now supplying 19 percent of this country’s electric generation. Molten salt reactors that use thorium will not replace them. But the thorium technology still has place in the mix, as evidenced by the international research now occurring. China is furthest along and if it succeeds, the science will be applied elsewhere.