Chinese molten salt reactor allowed to start

China has given the green light for the start of the experimental nuclear reactor TMSR, the thorium-depleting molten salt reactor. This research reactor is the first since the 1960s to operate with thorium, in theory much safer than uranium.

After four years of construction (and ten years of preparation), the world’s first new thorium-fueled molten salt reactor will go into operation this year in the Chinese desert city of Wuwei. It is two years ahead of schedule. However, it is a demonstration project: TMSR only supplies two megawatts of heat and will not convert it into electricity. By comparison, even a relatively small nuclear reactor like the one in Borssele supplies around five hundred megawatts of electricity.

Landmark

TMSR is the world’s first working molten salt reactor since the US experimented with two test reactors in the 1960s. ‘A milestone’, replies Dutch professor Jan Leen Kloosterman, expert in nuclear reactors at TU Delft. ‘We will learn a lot from this for future molten salt reactors.’

Practical experience

With the test installation, China mainly shows that it has the necessary technology for molten salt reactors. TMSR is meant to gain hands-on experience, Kloosterman says: with it, China can design its first generation of thorium plants that actually deliver power. The country has expressed the ambition to be completely climate neutral by 2060.

Game changer

Molten salt reactors are seen as a game changer for nuclear energy. Thirty times more of the spent thorium is available than uranium, but it is not itself fissile. An injection of radioactive material causes the thorium to transform into uranium, which then cracks and generates heat.

If it succeeds in getting molten salt plants up and running, the benefits will be great. For example, thorium itself is not radioactive, and the radioactive waste from a molten salt reactor has rapidly become harmless. The temperature cannot get out of hand during a meltdown either, because the fuel mixture then flows out of the reactor through an easily melting plug, so that the nuclear fission reaction stops. A disadvantage is that the salt mixture corrodes the metal of the reactor. TU Delft is therefore investigating materials that can withstand this.

Reactor vessel for the molten salt reactor TMSR. Source: Shanghai Institute of Applied Physics

Thorium plants

Meanwhile, Kloosterman is following the Chinese project with interest. “They will gain valuable practical experience there. The first generation of thorium molten salt plants will be very similar to this design.’ China is thus ahead, but according to the reactor expert, they were able to tackle this project quickly, among other things by staying close to the old American designs.

Do you find this topic interesting? Take a look at the file ‘Nuclear energy in the Netherlands’.

Europe is opting for a more basic scientific approach, according to Kloosterman. ‘It would be really nice if the reactor could work without the graphite moderator that the TMSR still has. Then you can more quickly and more efficiently convert more thorium into uranium and efficiently burn up plutonium, which is now useless.’

Brush harness

Even so, any new nuclear reactors in Borssele will probably not run on thorium. Kloosterman sees more in existing light water reactors that are already commercially available. “The climate problem is so acute that you don’t have to wait for thorium plants to come on the market. You have to go to work now.’

Text: Gieljan de Vries
Opening image: Chinese test facility for the circulation of molten salt. Photo: Thorium Energy World

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