Saturday, December 15, 2012

Thorium Reactors the Future of Energy?


An experimental Thorium Reactor built in 1954

What's the Thorium Storium?

I apologise for dropping the ball on the Thorium question in recent months. I have been doing a little bit more research reading in the last few weeks, and the ever-present question in my mind is; Is Thorium a viable interim answer to the Energy Crisis?

There are a bunch of pro-Thorium actions groups, interested parties, and even some elements of the loonies, all strongly promoting the use of Thorium as a safe, cheap, and viable nuclear fuel, the answer, they say, to the worlds energy needs.

The pro-Thorium arguments include:

1. Thorium is very plentiful.
2. Thorium is cheap, only a tiny fraction of the cost of Uranium.
3. Thorium is very much safer than Uranium or Plutonium.
4. Thorium waste is not as toxic and much easier and cheaper to dispose of than the current nuclear fuels.
5. Thorium Molten Salt Reactors by definition simply cannot explode like Chernobyl or Fukushima, and will fail-safe self shut down in an emergency.
6. Thorium cannot be used to make atomic weapons.

The BOMB and Thorium

The Atomic Weapons, the anti-Thorium people would say:

The Thorium reaction process has to use some Uranium. During the reaction process Uranium 232 and 233 are mixed together and generally cannot be separated. As a result the enrichment of the uranium to weapon’s grade levels is theoretically not possible. However, Uranium 233 has been tested in at least one nuclear warhead, but the explosive power was much lower. There is no clear indication of how the contamination from Uranium 232 might impinge on the process.

Some reports suggest that Germany has experimented with a secretive project to breed Protactinium 233 from Thorium 232. Protactinium 233 naturally degrades into Uranium 233 provided that it is not subject to further radiation bombardment after transmutation has commenced otherwise it becomes contaminated.

Essentially, as I understand it, there is at least a healthy doubt about the assertion that Thorium is not capable of fuelling atomic bombs.

Some Other Problems with Thorium

While Thorium advocates would say that at least the interim use of Thorium is inevitable, there are several difficulties and roadblocks on the path towards it's universal use.

(1) One big problem is that some reactor designs would create significant 233U, a long-lived, dirty, and very dangerous radioactive waste product.
(2) Thorium reactor efficiency has been shown to work well in laboratory situations, but replicating similar high levels of fuel burn could present challenges in the real world.
(3) Many unanswered questions remain about the nuclear reaction chains involved in Thorium reactors. Indications would seem to point towards the fact that they either produce some fission products capable of corrupting Uranium 233, or they will require Uranium recycling technology that is, as yet, unproven.

Is Thorium the Future?

Well maybe – and maybe not. There are some clear arguments regarding the advantages of Thorium as a nuclear fuel. But equally clear that the technology is largely unproven and there are certainly some disadvantages to its use. 

 "Small" and "Low-Cost" Thorium Reactor design being proposed

The pro-Thorium lobby argue that Molten-Salt reactors, like those pioneered in the 1960s, at least on paper, display all the benefits of traditional Thorium driven reactions without the negatives. The proposals are for the use of several small reactors on sites, rather than the current trend for huge installations.

The pro-Thorium lobby suggest that smallish Thorium Liquid Salt Reactors could be factory built and transported to the operating sites, thus saving vast amounts of money.

Another factor to consider is that vested interests in the nuclear industry would tend to hold back a move away from Uranium – something similar to the drag effect seen from the petroleum industry in the move to sustainable energy.

International Thorium Research

Because of the vast costs involved in Thorium research, there is an emerging trend where organisations involved in Thorium research in the United States are partnering with those in Russia and China

Despite this co-operative approach, a study, published last year, suggests that Thorium reactors, because of the huge capital investment needed, are not expected to be shipping from the local Walmart any time soon despite the hoped for potential benefits.

Thorium in mixed oxide (MOX) fuels reactors is a more likely development in the near future. Some benefits still exist in the use of Thorium MOX such as, the lowering radioactive waste and the increase in the destruction of deadly Plutonium.

Overall the general feeling seems to be that the likelihood of Thorium completely replacing Uranium, at least in the short to medium term, is very low.


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