October 28, 2016


Molten Salt Reactors Could Soon Help Power Earth--And One Day Mars (Sarah Scoles, 10/28/16, wired)

Shu's nuclear power device is called a "two-fluid molten salt reactor." The full details are in the patent, but the basic idea is this: The first batch of molten salt is full of a thorium compound, which eventually decays into uranium as neutrons bombard the mixture. That uranium goes into the second batch of molten salt and circulates into the reactor's graphite-filled core.

There, it encounters slowed-down neutrons, which kick off a fission chain reaction--that's the energy-producing part. The first batch of salt then absorbs the heat from the reactions, cooling the system. (In typical nuclear reactors, water does the cooling.)

This system is self-regulating: If the reactions happen too fast and the reactor gets too hot, the salt naturally expands out of the core, which cools it off--think transferring hot coffee from a tiny cup to a cookie sheet (don't ask questions). That makes the reactor pretty meltdown-proof.

That's great for Mars, obviously--any energy supply on a newly-formed colony is going to have to be pretty foolproof. Not worth setting up a trillion-dollar settlement if your reactor gives everyone radiation poisoning (at least not before the sun does, anyway). Plus, the planet has plentiful thorium, and nuclear power doesn't care if dust storms dot out the Sun for months at a time (solar panels, on the other hand, care very much). That's why Shu hopes NASA will back the R&D for his reactors.

It's also great for Earth. While Shu's specific design is novel, the idea comes from the 1960s, when Oak Ridge National Laboratory made a molten salt reactor. The World Nuclear Association calls them "a promising technology today," and China and India are sinking effort into their own designs. That hasn't happened yet, though--which is where Shu's plan comes in.

Posted by at October 28, 2016 7:05 PM