Thorium Molten Salt Nuclear Energy. What's That!

 

I wrote a two-part essay on:

An Eternal Source of Energy from the Oceans (Part 2)

https://scientificlogic.blogspot.com/2024/09/an-eternal-source-of-energy-from-oceans.html

In the 2^nd part essay, I mentioned China intends to build a thorium molten salt nuclear power station as the world first here:

https://www.scmp.com/news/china/science/article/3271978/china-sets-launch-date-worlds-first-thorium-molten-salt-nuclear-power-station

I then promised I shall write an article on China's intentions to use thorium molten salt even though this is a new area in nuclear physics I have less knowledge. In fact, China's intention is the world’s first.  But I can still comment after lots of literature search and further reading. I always read a lot as part of my educational culture.

Let me try.

Thorium molten salt reactors (TMSRs) are an advanced type of nuclear reactor that use thorium-232 as a fuel. The technology is seen as a potential game-changer in nuclear energy due to its safety features, reduced waste production, and the abundant availability of thorium.

How does molten thorium salt reactors work?

First, they have the fuel and salt mixture. In a TMSR, thorium is dissolved in a molten salt mixture, typically a fluoride or chloride salt. This molten salt serves as both the fuel and the coolant for the reactor.

Then they proceed to neutron absorption and breeding. Thorium-232 itself is not fissile, meaning it cannot directly sustain a chain reaction. However, when thorium-232 absorbs a neutron, it transforms into thorium-233, which then decays into protactinium-233 and eventually into uranium-233.

Uranium-233 then becomes fissile, meaning it can sustain a nuclear chain reaction. When uranium-233 nuclei absorb neutrons, they split (fission) into smaller nuclei, releasing a large amount of energy.

In the nuclear fission reaction, the fission of uranium-233 releases energy in the form of heat. This heat is then transferred to the molten salt, which circulates through a heat exchanger.

The next step China will do is heat transfer and electricity generation. The molten salt transfers the heat to a secondary loop, where it is used to produce steam. The steam then drives turbines connected to generators, producing electricity.

What about continuous fueling and waste management?

One of the advantages of TMSRs is that they can be continuously refueled. Fresh thorium can be added to the reactor without shutting it down, and the molten salt can be processed to remove fission products and other waste. The waste produced by TMSRs is less long-lived compared to traditional uranium reactors, making it easier to manage.

What is the physics behind energy production?

They need neutron moderation. In TMSRs, a neutron moderator (often graphite) is used to slow down fast neutrons, making them more likely to be absorbed by thorium-232 to start the breeding process. The slower, "thermal" neutrons are more effective at sustaining the chain reaction with uranium-233.

Then comes the fission chain reaction. The uranium-233 produced in the reactor undergoes fission when it absorbs a thermal neutron. Each fission event releases a significant amount of energy (typically around 200 MeV) and additional neutrons, which can then induce further fission reactions, sustaining the chain reaction.

Nuclear physicists and nuclear plant engineers will need to look at the breeding ratio. The breeding ratio in a thorium reactor is critical. It determines whether the reactor produces more fissile material (U-233) than it consumes. Ideally, the reactor should have a breeding ratio of just above 1 to maintain a sustainable cycle.

Let us now  look at the advantages of thorium molten salt reactors.

First consideration is safety. Molten salt reactors operate at atmospheric pressure, reducing the risk of explosive pressure accidents.

Second, the molten salt has a high boiling point and excellent heat transfer properties, which helps in efficiently removing heat from the reactor core.

Third, if the reactor overheats, the molten salt can be drained into a passively cooled storage tank, automatically shutting down the reaction.

What about the radioactive waste and storage?

TMSRs produce less long-lived radioactive waste compared to conventional reactors. The waste that is produced also contains fewer transuranic elements, which are the most problematic in terms of long-term storage.

However, the advantage is there is an abundance of fuel supply. Thorium is more abundant in nature than uranium, and it can be used more efficiently in reactors.

The other advantage is proliferation resistance. By this I mean the U-233 produced in thorium reactors can be contaminated with U-232, which is highly radioactive and makes it difficult to use the material for weapons.

But what are the challenges?

 China will need more technological development.  While the concept of molten salt reactors has been known for decades, significant engineering challenges remain, particularly in materials that can withstand the highly corrosive environment of molten salts at high temperatures.

They will also need to consider the fuel cycle.  The thorium fuel cycle requires reprocessing to separate protactinium and uranium, which adds complexity and cost.

Thorium molten salt reactors represent a promising advancement in nuclear technology, offering potential safety, efficiency, and waste disposal advantages over traditional reactors. The physics behind these reactors relies on the conversion of thorium-232 into fissile uranium-233, followed by a controlled nuclear chain reaction that produces heat for electricity generation. If successfully developed, TMSRs could play a significant role in the future of clean energy production hopefully?

I do not have sufficient knowledge on nuclear energy production to comment further, but all I can see is the disposal of radioactive waste is problematic. This is a very formidable challenge which ever method or technology China or other nations may try to develop. Top of Form

As I have already written earlier, the oceans would be our safest solution for our energy-hungry world as the waters will yield an un-endless supply of energy very safely for all eternity even if the Sun goes out in another 5 billion years.

Unfortunately, humanity will no longer be not around anymore as I have explained that in several articles here in this blog of mine. You may check them out.

Take Care, especially for our souls that shall live for all eternity. 

 (I shall write on Translational Medicine and its problems for my next article) 

Jb lim