China working on uranium-free nuclear plants in attempt to combat smog | Hacker News Reader

China working on uranium-free nuclear plants in attempt to combat smog

theguardian.com

15 pointssasvari8 comments

"A team of researchers in Shanghai has now been told it has 10 instead of 25 years to develop the world's first such plant."

Or else what?

Oh. Ohhhhhhhh.

or else funding stops?

But it's so much fun to think of them getting killed because they couldn't deliver.

Can a pure thorium reactor even work in theory? I thought it needed a neutron source to sustain fission like uran or something similar

You are correct.

You start with thorium plus a fissionable isotope of uranium or plutonium. The fission neutrons convert the thorium to U-233, which is fissionable. After that you rely on U-233 fission for neutrons and keep feeding thorium to it.

It can be done with solid fuel but with liquid fuel it works out really nicely. You can fission pretty much everything and have just fission products left over, which means a lot less nuclear waste that only has to be contained for a few hundred years. And you're not shipping anything fissionable to or from the reactor.

Was wondering if the headline was misleading in mentioning 'uranium free'...

Incidentally India's 3-stage plan is meant to use its vast Thorium deposits in the 3rd stage:

http://en.wikipedia.org/wiki/India%27s_three-stage_nuclear_p...

which eventually uses Pu-239 from the fast-breeder reactors (2nd stage) as the neutron source to take it to the 3rd stage.

IIRC, the original plan predicted to reach the 3rd stage in the 90s', but due to various sanctions, it is still stuck in the first stage; probably it will speed up now due to the Indo-US nuclear deal during the 2nd term of the Bush administration.

It needs a neutron source to start fission, but once it's going, in theory it can self-sustain as Th decay genearates radio-isotopes. Furthermore it can breed fissile fuel with thermal neutrons, which is generally seen as an advantage.

The neutron economy, however, is very slim. Several of the intermediate decay products are neutron absorbers. This is why you see a lot of proposed liquid thorium reactors, there are various proposals to use chemical reactions to remove neutron absorbers from the fuel while the reactor is running (something that would be challenging with a solid reactor).

That's a terrible title. A Uranium fuel cycle would combat smog just as much. Thorium plants can in principle be less risky, though is you factor out proliferation and reprocessing risk it is possible to make Uranium fuel plants that are inherently safe from meltdown, too.

The news is that China is about to outrun everyone in bringing nuclear plants online. They have a lot of construction under way.

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