An experimental reactor on the edge of the Gobi Desert will run on thorium. The plant was completed at the end of August. The Nature writes.
The first tests were scheduled to begin during September.
The research reactor will generate enough electricity for a thousand homes.
If the project succeeds, China will then build a thorium-powered power plant that can produce 373 megawatts by 2030. That’s enough to provide electricity to hundreds of thousands of homes, according to Nature.
Conventional nuclear power plants run on uranium in a solid form and often use water as a coolant and moderator. China research reactor with different design.
Instead of uranium, thorium dissolves in liquid salts.
This technology was developed over 50 years ago, but has never been used commercially. China launched investment in salt smelters using thorium in 2011.
This would be one of many “ideal technologies” for the country to reach its climate goals, energy model Jiang Kejun at the Beijing Energy Research Institute tells Nature. China aims to become carbon neutral by 2060. Currently, they get 57 percent of their energy from coal, According to NRK.
Thorium is a waste product related to mining on rare earths in the country.
The use of thorium reactors has also been proposed in Norway. It is estimated that we have 87,000 tons of thorium within our borders, according to one source Report from the International Atomic Energy Agency and the Office of Nuclear Energy of the Organization for Economic Co-operation and Development From 2014. Most of this is located in the Fens field in Telemark.
Ole Kristen Rystad is Head of Environmental Safety and Radiation Protection in the Department of Energy Technology. He is also a former reactor manager at the Jeep II reactor in Kjeller, Norway.
Reistad tells forskning.no that the project in China is certainly exciting.
– There is a lot about technology that is interesting and that is different from uranium technology.
But he doesn’t think it’s clear that this technology will be any safer than others.
– I am a sober soul in these contexts, says the former reactor manager.
From an experimental power plant to a usable concept, the road is long and thorny, says Rystad. He also believes it would be premature to link the project to climate and climate measures.
In general, much of the discussion in this field is characterized by technological optimism related to untested systems.
Stores less radioactive waste
In theory, there are many advantages of a thorium salt smelter compared to conventional nuclear power.
- Thorium is a radioactive element with atomic number 90.
- A mineral with this element was discovered in Norway, analyzed and named by the Swede Jonas Jacob Berzelius.
- The name comes from the Norse god Tor.
- Norway has relatively large deposits of thorium.
- The amount of radioactive waste could be much smaller and harmful over a shorter period of time, according to the book “We Are Stardust – Nuclear Physics for Most People” by Sunniva Rose.
- Plutonium is never produced as a waste product. It is difficult to make weapons using thorium.
- The technology must be fairly secure. If something goes wrong, the salt melt can be drained into a chamber under the reactor. A salt smelter reactor operates at a high temperature but at a lower pressure than normal reactors.
Thorium turns into uranium
Thorium is called fertility. It cannot be directly divided and released energy. In nature, we find the element thorium 232. It is weakly radioactive and has a half-life of 14 billion years.
To get a material usable for nuclear energy, thorium must first “eat” a neutron, and this leads to a small series of changes that ends up with thorium becoming uranium-233.
This isotope is fissionable, so it can decay and release a lot of energy.
Plutonium is not formed as a waste product. Unlike when you start with uranium.
Uranium exists naturally, mostly in the form of uranium-238 which cannot decay. About 0.7 percent of uranium-235, a fissile material, is found. It is this isotope that decomposes and generates energy. Uranium is often enriched to contain 3-5 percent uranium-235.
In the reactor, uranium-235 mostly produces energy, while uranium-238 eats neutrons and becomes plutonium and other substances.
Plutonium can be used as fuel in a nuclear power plant. It can also be used to make atomic bombs, such as uranium-235 in a sufficiently high concentration.
Need something to get started
Since thorium is enriched, you need something extra to start the reaction.
That’s part of the problem, but also what makes thorium more difficult to use for weapons, says Ole Kristen Rystad.
– You can either have a particle accelerator, or you can use other fissile materials, such as uranium or plutonium, and start the process with it.
In other words, you don’t necessarily have to avoid dealing with substances of concern.
It is possible to use more fuel
Reistad says it is true that thorium produces waste that should not be stored as long as it is waste from conventional nuclear power plants.
– It is important in principle. But we don’t know how different they are in practice. Whether you have to take care of the waste for a few thousand years or a few hundred thousand years, I’m not sure how much difference there must be in the actions they take now. Because many actions also come from simply not accepting the local community, says Rystad.
The amount of waste would be smaller anyway if the thorium fuel was recycled and used multiple times.
– With the salt dissolving technology, you can use more materials. In normal nuclear power plants, only a small percentage of the available uranium is used, Rystad says.
First, most uranium is non-fissile. Second, there are limitations associated with uranium being in a solid state.
Uranium fuel in conventional reactors has a specific geometry, such as sticks or plates. As the atoms decay, the fuel changes slightly, so you can only make use of a few percent before it deforms. When you have molten salt, you don’t count on preserving geometry.
Is thorium safer?
Is it safer with a thorium-salt melting reactor?
It uses the principle that there is a chain reaction. Reistad says security requires a lot no matter what technology you use.
He also says that if you have an economically efficient salt smelting reactor that produces little waste, the fuel should be recycled.
The reprocessing industry that we’ve actually done requires everything we can to try not to do that in the uranium space. We don’t want uranium to be circulated throughout the community, and it’s proven to be quite demanding in terms of radiation protection to make that happen in an acceptable way.
Thorium waste contains, among other things, fissile uranium-233 that can be used to make weapons. The waste is also dangerous due to the strong gamma radiation and must be handled by robots.
Other challenges are that materials other than those used to care for the strong salts mixed with radioactive waste are needed.
It has to be qualified to also be suitable for accident situations, and that’s a tedious task that takes time, says Reistad.
I would have been somewhere else if we started with thorium 50 years ago
Despite the challenges, Reistad says that the thorium-salt melting reactor is a very interesting concept and in principle has a number of aspects that could provide safer nuclear power.
What makes me sad, by empirical thinking, is that when you started using nuclear power in the 1940s and 1950s, you started with uranium. If we instead start with thorium, we may have come a long way now to have a sustainable nuclear energy industry based on healthier principles than we have.
Rystad says it’s hard to say whether other countries would be more interested in thorium-based nuclear power if China were successful.
– There are countries that are today completely at the forefront of nuclear energy, for example Germany, which said that in principle it does not want nuclear energy.
India, on the other hand, is interested in using thorium and is working on the case.
China is not only interested in thorium-based nuclear power. It’s also great over conventional nuclear power.
All the so-called “nuclear energy renaissance” lies primarily in China’s development. There is no renaissance, there is development in China. Today, China is doing a tremendous job in building normal nuclear power. In fact, it’s something that gives us hope that it’s part of the background to what China agrees on on climate.
The question is whether China as a society has had the opportunity to weigh the associated risks against the climate benefits, says Rystad.
(This article was first published in Forsking).
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