China Switching to Thorium

Molten Salt Reactors (MSRs), which were developed and tested in the 1960’s and 70’s at Oak Ridge National Laboratories but then moth-balled, are back. China is set to turn on their 2MW experimental Thorium MSR at Wuwei, on the edge of the Gobi desert, possibly to power moisture farms as they do on Tatooine.

In addition to China, several companies around the world are developing MSR technology. Terrapower, Utah Green Energy, Terrestrial Energy and Texas Thorium are the most prominent patent holders. Leading in MSR patent assets is Terrapower, whose primary investors include Bill Gates, Charles River Ventures and Khosla Ventures.  

Thorium molten salt reactors can be built in the desert because no water is needed to cool them. This and a few other features can explain why so many companies are developing Thorium MSR technology. 

Uranium reactors create byproducts that take several weeks to degrade to the point that they won’t cause a reactor meltdown.That’s why these old-school reactors need extensive backup power to run the cooling system for long periods of time even after the reactor is “stopped”. In contrast, the major byproducts from the thorium reactors are degraded after only 30 minutes, making these reactors ultra-safe and eliminating the need for extensive backup power. 

A molten salt reactor is also inherently load-following, which means the reactor automatically increases or decreases reaction in response to the load placed on it. The reactor can do this because the reaction takes place in a liquid state, which expands and contracts in response to the amount of heat removed to generate power. This expansion/contraction changes the distance between the atoms in the liquid, which changes the probability of a neutron striking a nucleus, thereby adjusting the fission reaction speed. No human intervention is needed and so no human error is possible. In the age of ransomware taking our infrastructure hostage, this is a good feature to have.

Another good security feature is the automatic “kill-switch” designed into these reactors. These reactors have a “frozen” salt plug at the bottom that is kept solid by cooling fans. If the reactor system overheats, the plug “thaws” and releases the molten salt into a containment pit that spreads out and cools the salt so that it solidifies and the reaction stops. Molten salts also don’t vaporize, so the reactors are not high-pressure and have no risk of explosion.  

The nuclear waste from these reactors is safe after 300 years. Contrast this with plutonium waste that has a half-life of 24,000 years. Speaking of nuclear waste, the Thorium MSRs can also be used to “burn up” existing uranium/plutonium nuclear waste. In fact, Moltex is developing a reactor specifically designed to burn this waste

This is not unproven technology. The first molten salt reactor ran for over 5 years at Oak Ridge National Laboratory and in any case, humans have made technology work when we had to, so Thorium MSRs are highly likely to evolve into a major energy source. For example, it’s been pointed out that traditional Thorium MSRs need some radioactive Uranium 233 to “kick-start” them and that opens the door to nuclear weapons. To eliminate the need for this radioactive material, Texas Thorium, in partnership with Texas A&M University, is developing a system where particle accelerators fire protons at the salt, which releases neutrons to start the reaction. This means Thorium would be the only fuel and it can’t be turned into a nuclear weapon per se

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