Many people fear existing nuclear power plants because: a) they have the potential to melt down if something goes wrong, b) because they produce nuclear waste with an extremely long life, and c) because they house and have the ability to produce bomb-grade materials. Here’s a descripton of a basic uranium-fueled nuclear reactor:

With a thorium-fueled reactor, the system won’t melt down and the toxic waste lasts a few hundred rather than a few thousand years:

New age nuclear

For more into see: How Nuclear Power Works

From the article:

Thorium itself is a metal in the actinide series, which is a run of 15 heavy radioactive elements that occupy their own period in the periodic table between actinium and lawrencium. Thorium sits on the periodic table two spots to the left (making it lighter) of the only other naturally occurring actinide, uranium (which is two spots to the left of synthetic plutonium). This means thorium and uranium share several characteristics.

According to Reza Hashemi-Nezhad, a nuclear physicist at the University of Sydney who has been studying the thorium fuel cycle, the most important point is that they both can absorb neutrons and transmute into fissile elements. “From the neutron-absorption point of view, U-238 is very similar to Th-232″, he said.

It’s these similarities that make thorium a potential alternative fuel for nuclear reactors. But it’s the unique differences between thorium and uranium that make it a potentially superior fuel. First of all, unlike U-235 and Pu-239, thorium is not fissile, so no matter how much thorium you pack together, it will not start splitting atoms and blow up. This is because it cannot undergo nuclear fission by itself and it cannot sustain a nuclear chain reaction once one starts. It’s a wannabe atom splitter incapable of taking the grand title.

What makes thorium suitable as a nuclear fuel is that it is fertile, much like U-238.

Natural thorium (Th-232) absorbs a neutron and quickly transmutes into unstable Th-233 and then into protactinium Pa-233, before quickly decaying into U-233, says Hashemi- Nezhad. The beauty of this complicated process is that the U-233 that’s produced at the end of this breeding process is similar to U-235 and is fissile, making it suitable as a nuclear fuel. In this way, it talks like uranium and walks like uranium, but it ain’t your common-or-garden variety uranium.

And this is where it gets interesting: thorium has a very different fuel cycle to uranium. The most significant benefit of thorium’s journey comes from the fact that it is a lighter element than uranium. While it’s fertile, it doesn’t produce as many heavy and as many highly radioactive by-products. The absence of U-238 in the process also means that no plutonium is bred in the reactor.

As a result, the waste produced from burning thorium in a reactor is dramatically less radioactive than conventional nuclear waste. Where a uranium-fuelled reactor like many of those operating today might generate a tonne of high-level waste that stays toxic for tens of thousands of years, a reactor fuelled only by thorium will generate a fraction of this amount. And it would stay radioactive for only 500 years – after which it would be as manageable as coal ash.

So not only would there be less waste, the waste generated would need to be locked up for only five per cent of the time compared to most nuclear waste. Not surprisingly, the technical challenges in storing a smaller amount for 500 years are much lower than engineering something to be solid, secure and discreet for 10,000 years.

But wait, there’s more: thorium has another remarkable property. Add plutonium to the mix – or any other radioactive actinide – and the thorium fuel process will actually incinerate these elements. That’s right: it will chew up old nuclear waste as part of the power-generation process. It could not only generate power, but also act as a waste disposal plant for some of humanity’s most heinous toxic waste.

This is especially significant when it comes to plutonium, which has proven very hard to dispose of using conventional means.

The article discusses two different styles of reactor that have been developed to use thorium as a fuel.