Exploring Hydrocarbon Depletion
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Page added on April 21, 2012
When it comes to nuclear power, there’s talk of all sorts of technologies and fuels — things that could make the average guy’s head spin. But if you think nuclear energy is an efficient and pollution-free way to make electricity, consider “thorium” and “molten salt reactors.”
Huh? On the periodic tables, 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, 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.
“Thorium is the most abundant nuclear material on earth,” says Clinton Bastin, who was with the U.S. Atomic Energy Commission and the U.S. Department of Energy from 1955 until 1997. “It should eventually be used in nuclear reactors because it is so plentiful. But it should not be used now because it introduces the problem of highly radioactive material that is very difficult to deal with.”
Bastin, who is also a former VP of the World Council of Nuclear Workers, explained to this reporter that there are demonstration projects now occurring involving thorium. Active trials are taking place in China and India, and to some extent in Canada. But no country is using a significant amount of thorium to produce electricity, much less in molten salt reactors.
Thorium is abundant in nature, with about four times the amount in the earth’s crust than uranium. When used as a nuclear fuel, the whole cycle produces less radioactive waste than does uranium. But, the thorium fuel cycle still makes radioactive material that must be warehoused and some say it does produce an isotope of uranium that could be used in nuclear weapons, although plutonium that is the preferred method is not a byproduct.
Why has this country chosen uranium over thorium? The decision was made in the 1950s during the emergence of nuclear power generation. That was during the Cold War and the U.S. government had decided that the national treasury would be invested in uranium fuels, as they can be more easily enriched to make nuclear bombs.
Today, the U.S. might have chosen a different path. But it would be too costly to retrofit the existing nuclear energy infrastructure to comport with the thorium fuel cycle. The supply chain is now fully stocked and includes everything from uranium suppliers to reactor designers.
“It is possible to convert the existing reactors to thorium reactors over time,” says Thomas Drolet, a nuclear energy expert with his own consulting firm in Englewood, Fla., in a phone interview. “But it would be high capital costs. What you really want to do is to start from scratch.”
The 104 nuclear power plants operating in the United States today use so-called second generation light water, solid fuel reactors. They operate, on average, at more than 90 percent capacity and have been working safely for at least 36 years.
“Third generation” light water reactors are going up predominately in India and China and they are the ones that are to be constructed by Southern Company andScana, both of which were recently approved to build by the U.S. Nuclear Regulatory Commission. Those third generation reactors have superior fuel technology, thermal efficiency and safety features.
The next-generation reactors, called “fourth generation,” are those that run at much higher temperatures. They are even more efficient than those in the third generation, giving them the potential to produce more electricity at less cost. The high temperatures also enable hydrogen production as well as a variety of industrial applications.
Thorium is most suited to run in fourth generation “liquid fuel” reactors, which operate at lower pressures and which are therefore safer. Such molten salt 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. Critics say that it is still difficult to maintain high thermal efficiencies, which diminishes the economic case for those liquid fuel reactor’s over today’s technologies.
“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 spoke with this writer by phone. “But the similarity ends there. Inherently, thorium is much more abundant and easier to handle.”
China, he adds, is likely to get there first. It is demonstrating a modern thorium reactor and it could have one in full-scale production by 2020. China is about 70 percent of the way to commercialization, he notes, emphasizing that the United States invented the technology and could leapfrog that nation.
What’s stopping this country? Beyond the established interests that have already invested huge sums in the current technologies, there are questions about the creation of huge piles of thorium — something that would come with immense regulatory oversight and the associated expenses.
As such, Kutsch is saying that the industry would be willing to manage a centralized “rare earth” refinery that would safeguard or find uses for the thorium that has been stockpiled. His group would also like the U.S. Nuclear Regulatory Commission to write the rules and regulations for liquid reactors that use the thorium fuel cycles.
The reality is that solid fuel reactors using uranium are now supplying 20 percent of this country’s electric generation. Liquid fuel reactors, or 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.