Thorium Reactor energy cycle (click to expand).
A very interesting article on Thorium Reactors by John Ridd was published on Australia's On Line Opinion , January15, 2013 - see http://www.onlineopinion.com.au/view.asp?article=14571 . Article states in part:
"Two books that influenced me over the last year are Thorium, energy cheaper than coal by Robert Hargraves...Hargraves is an expert on energy policy. His detailed knowledge is encyclopaedic and almost daunting;...
...Hargraves also worries about air pollution per se and rising population. He talks of 'an unsustainable world'. His basic thesis is that most countries cannot afford to stop using coal power stations and that they will not stop – unless a cheaper alternative is available; hence the title of the book.
...The Uranium isotope 235 is said to be 'fissile'. When a U235 nucleus is hit by a neutron it splits roughly in half, gives out enormous energy, and spits out a lot more neutrons which in turn hit other U235 nuclei and so on. Controlled, that 'chain reaction' provides useful heat; uncontrolled it gives a big bang. Thorium is not fissile, it is said to be 'fertile'. When a neutron hits a Thorium 232 nucleus it makes its eyes water but it only spits out one particle and then later another which transmutes it into a Uranium 233 atom – which is fissile and a form of chain reaction then starts producing energy. So it is breeding its own fuel. A small amount of Uranium is needed to kick start the process.
Hargraves argues strongly that the best bet for producing energy cheaper than coal is the Liquid Fluoride Thorium Reactor LFTR. There is nothing new in the idea; much research and construction of reactors went on in the 1950s and 1960s. A good example was the Oak Ridge Lab (USA) molten salt reactor experiment which operated successfully for 4 years up to 1969. Work on LFTRs and similar has taken place in many countries. 'Since 1996 India has operated its experimental Kamini 30kw reactor… and… India's national strategy is to produce 30% of its electricity from thorium by 2050'.
Hargraves claims that LFTR reactors have many advantages over 'normal' Pressurised Water Reactors PWRs. Examples are:
· It promises to be able to produce electricity cheaper than coal
· LFTR reactor 'cleans' itself of products that damage a PWR; for example Xenon, which affects efficiency, simply bubbles out.
· A PWR operates at 160 atmospheres, whereas a LFTR works at normal atmospheric pressure so LFTR is safer.
· LFTR operates at much higher temperatures, a fact that increases efficiency of electricity production.
· LFTR produces less than 1% of the radiotoxic wastes compared to PWR.
· LFTR does not produce material suitable for bomb manufacture, it is hence proliferation resistant. (Hargraves places a high priority on non-proliferation.)
· Thorium is effectively an inexhaustible resource.
In keeping with his aim of 'energy cheaper than coal', Hargraves discusses in some depth a number of reactors that are under consideration across the world. Two that interested me are:
(a) Denatured Molten Salt Reactor DMSR also uses Thorium; it could be a cheap source and is 'likely to be the first molten salt reactor to reach the market', but it requires more U235 to keep it running than LFTR.
(b) The Toshiba Westinghouse AP 1000 which is a PWR reactor but is far superior to older reactors due to over 50 years of experience and development.
China is moving rapidly down the nuclear road. It has 14 plants in operation and 25 under construction, with a capacity of 60GW rising to 200 GW by 2030. In comparison the Three Gorges hydropower project which displaced well over a million people generates 18GW. China is using best ideas from everywhere – AREVA (Europe), Toshiba/Westinghouse, Pebble Bed reactors based on German work and fast breeder reactors from Russia. Notably [China] has set up and funded a project to develop Thorium LFTR reactors. Hargraves claims that then Premier Wen Jiabao says that China will accelerate …nuclear energy and 'put an end to blind expansion in industries such as solar energy and wind power'."
see whole OLO article at http://www.onlineopinion.com.au/view.asp?article=14571
Use of Thorium reactors might be a bonus for Australian miners as Australia is estimated to have the largest Thorium "resources" in the world http://www.ga.gov.au/minerals/mineral-resources/thorium.html .
However John Ridd might be overly optimistic about Thorium reactor's technical and economic viability given the very low use and slow development of Thorium reactors over the last 60 years.
Still, this is in comparison with a near cartel of Uranium miners, U reactor builders and operators. The dual-use (military-commercial) value of U may have also artificially favoured U reactor development at the expense of Thorium reactor development and economical functioning.
All in all if Australia is ideologically opposed even to Thorium reactors we can at least export it to future customers like India, France and China etc.
see also http://gentleseas.blogspot.com.au/2009/11/thorium-reactors-indian-and-australian.html .
On some Indian attitudes to Thorium reactors see http://defenceforumindia.com/forum/science-technology/23318-liquid-fluoride-thorium-reactor.html