26 August 2013

Thorium nuclear reactor trial begins, could provide cleaner, safer, almost-waste-free energy

At a test site in Norway, Thor Energy has successfully created a thorium nuclear reactor — but not in the sense that most people think of when they hear the word thorium. The Norwegians haven’t solved the energy crisis and global warming in one fell swoop — they haven’t created a cold fusion thorium reactor. What they have done, though, which is still very cool, is use thorium instead of uranium in a conventional nuclear reactor. In one fell swoop, thorium fuel, which is safer, less messy to clean up, and not prone to nuclear weapons proliferation, could quench the complaints of nuclear power critics everywhere.

In a conventional nuclear reactor, enriched uranium fuel is converted into plutonium and small amounts of other transuranic compounds. There are ways to recycle plutonium, but for many countries, such as the USA, it is simply a waste product of nuclear power — a waste product that will be dangerously radioactive for thousands of years. While the safety of nuclear power plants is hotly contested, no one is arguing the nastiness of plutonium. Any technological development that could reduce the production of plutonium, or consume our massive stocks of plutonium waste, would be a huge boon for the Earth’s (and humanity’s) continued well-being.

Enter thorium. Natural thorium, which is fairly cheap and abundant (more so than uranium), doesn’t contain enough fissile material (thorium-231) to sustain a nuclear chain reaction. By mixing thorium oxide with 10% plutonium oxide, however, criticality is achieved. This fuel, which is called thorium-MOX (mixed-oxide), can then be formed into rods and used in conventional nuclear reactors. Not only does this mean that we can do away with uranium, which is expensive to enrich, dangerous, and leads to nuclear proliferation, but it also means that we finally have an easy way of recycling plutonium. Furthermore, the thorium-MOX fuel cycle produces no new plutonium; it actually reduces the world’s stock of plutonium. Oh, thorium-MOX makes for safer nuclear reactors, too, due to a higher melting point and thermal conductivity.
Thor Energy’s thorium reactor in Halden, Norway. The rod in the middle of the picture contains thorium-MOX pellets, and is being inserted into the reactor (which is underground).
Thorium-MOX, in short, is about as exciting as it gets in the nuclear power industry. Before it can be used, though, Thor Energy needs to make sure that the thorium fuel cycle is fully understood. To do this, the company has built a small test reactor in the Norwegian town of Halden, where rods of thorium-MOX provide steam to a nearby paper mill. This reactor will run for five years, after which the fuel will be analyzed to see if it’s ready for commercial reactors.

The first batch of thorium-MOX pellets, which are inside the rods, was made in Germany; the next batch of pelles will be made in Norway; and the final, hopefully commercial-grade pellets will be made by the UK’s National Nuclear Laboratory. Westinghouse Electric Company, one of the world’s largest producers of nuclear reactors, is one of Thor Energy’s commercial backers.
(And yes, just in case you were wondering, the element thorium really is named after Thor, the Norse god of thunder. And yes, Norse mythology originated from Norway, where Thor Energy is based. Coincidence, I think not!)

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