Molten salt nuclear reactors could help eliminate existing waste

While we're on the subject of energy production - which if done properly may have far more drastic effects than the latest crop of idiot politicians - it's still worth giving nuclear a look-in. However, it looks increasingly unlikely to me that large-scale nuclear power will be needed. Maybe on small scales as backups for those rare occasions when wind and sun both fail across large areas, or for regions where these aren't practical for whatever reason. Still, we've already got existing nuclear waste, so it makes a lot of sense to develop a reactor that can consume it and reduce the problem. We could probably have had this decades ago if we'd invested properly instead of treating the n-word like the other n-word.

At least in theory*, this type of reactor can’t suffer the kind of catastrophic failure that happened at Chernobyl and Fukushima, making unnecessary the expensive and redundant safety systems that have driven up the cost of conventional reactors. What’s more, the new plants should produce little waste and might even eat up existing nuclear waste. They could run on uranium, which powers 99 percent of the nuclear power plants in the world, or they could eventually run on thorium, which is cleaner and more abundant. The ultimate goal of the Shanghai Institute: to build a molten-salt reactor that could replace the 1970s-era technology in today’s nuclear power plants and help wean China off the coal that fouls the air of Shanghai and Beijing, ushering in an era of cheap, abundant, zero-carbon energy.

* As I understand it, this statement may be over-cautious. The reactor is safe by design, not by clever engineering : if it overheats, it can't melt down.

That reactor at Oak Ridge ran on uranium; Weinberg’s eventual goal was to build one that would run exclusively on thorium, which, unlike uranium, cannot easily be made into a bomb. But the molten-salt experiment was abandoned in the early 1970s. One big reason was that Weinberg managed to alienate his superiors by warning of the dangers of conventional nuclear power at a time when dozens of such reactors were already under construction or in the planning stages.

Because conventional reactors require huge, costly containment vessels that can blow up in extreme conditions, and because they use extensive external cooling systems to make sure the solid-fuel core doesn’t overheat and cause a runaway reaction leading to a meltdown, they are hugely expensive.

Solid-fuel reactors cooled with molten salt can run at higher temperatures than conventional reactors, making them more efficient, and they operate at atmospheric pressures—meaning they do not require expensive vessels of the sort that ruptured at Chernobyl. Molten-salt reactors that use liquid fuel have an even more attractive advantage: when the temperature in the core reaches a certain threshold, the liquid expands, which slows the nuclear reactions and lets the core cool. To take advantage of this property, the reactor is built like a bathtub, with a drain plug in the bottom; if the temperature in the core gets too high, the plug melts and the fuel drains into a shielded tank, typically underground, where it is stored safely as it cools.

These reactors should be able to tap more of the energy available in radioactive material than conventional ones do. That means they should dramatically reduce the amount of nuclear waste that must be handled and stored.

Because they don’t require huge containment structures and need less fuel to produce the same amount of electricity, these reactors are more compact than today’s nuclear plants. They could be mass-produced, in factories, and combined in arrays to form larger power plants. All of that should make them cheaper to build.

https://www.technologyreview.com/s/602051/fail-safe-nuclear-power/