Wednesday, 12 February 2014
It appears such a process exists in the Thorium reactor cycle. Unlike conventional "fast-breeder" reactors that have to be kept from going super critical, the thorium reactor has to be kept from shutting down.
Fast-breeder type reactors aren't fail-safe, that is if things go wrong, it collapses into a safe state. Instead equilibrium is maintained by multiple levels of inventions designed to return a malfunctioning reactor to its normal state. The problem is these interventions can fail. Fukushima and Chernobyl both show how natural catastrophe and human failings can lead to catastrophic failure.
In the Fukushima scenario, the reaction would simply have shut down and the reactants dumped into holding tanks.
Pundits in the existing Nuclear industry especially those in the US seem reticent to take on this technology, while China and India are getting on with serious research.
It is not as if Americans haven't explored Thorium before, an experimental reactor was run by the DOE at Oak Ridge for 22,000 hours (5 years). There was only one problem, you can't get weapon's grade fissile material out of it. So, for strategic reasons Fast-Breeder reactors became flavour of the month.
There are some engineering issues, one of which is creating values that work well at 800C. One option is the thermal choke, a section of pipe that can be cooled until the salt freezes stopping the flow.
Thorium's half life is even longer than Uranium's. which means even less radiation comes out of Thorium than Uranium.
China maybe on the cusp of commercializing energy production from Thorium. Their rare-earths extractors have produced so much of it, they had to do something with it. Even though it is stored in large piles there is no melt down. This is perhaps a demonstration of how safe it is.
US Rare Earth mining appears hamstrung by regulations denying access to deposits with thorium content, even though thorium drops right out in the refining process. Perhaps because it might be a bad thing to have Thorium dumped like PET coke. It is heavy so it does not blow around. But even better, it can be used to make other nuclear waste safer. Because Thorium is an alpha emitter it can donate protons to other isomers and force their controlled decay into stable daughter isomers. Put another way it can help turn Uranium into Lead. Other possibilities include the production of isotopes for nuclear medicine.
The US rare-earth mining industry would very much like to lifting of this restriction related to thorium. In terms of ending reliance on slave worked mines run by war lords in Africa it seems like a better option. But depending on where in the US they choose to mine their maybe issues with environmental heritage assets.
Is it just me, or does anyone else have problems imagining the Uranium mining, refining industries offering a hand shake and "may the best industry win" to anyone contemplating development of a Thorium cycle. Or even an enthusiastic "let's retool for Thorium" from the nuclear industry.
Mining companies have there value locked up in the value of the mining resources they have available. If Thorium were adopted as a new fuel, the value of Uranium ore would collapse, and with the value of the mining company.
Building reactors is expensive, and you have to run them for their whole life to see a return. So developing a new technology, abandoning existing plant is not really an option. But most of all they would not want to piss-off there suppliers.
If "all of the above" were to start making sense, this would be a place to start, but ultimately, dumping coal, oil and gas in next 15-20 years is the best hope there is for having a habitable planet in the 22nd century.
The Thorium Problem
Molten Salt Reactors
"Th" the thorium documentary.