97% of world market supplies of rare earth elements (REEs) come from China and look to become insecure in regard to meeting "green" energy targets, since exports of REEs are scheduled to be retained for Chinese energy projects. REEs are essential raw materials for the fabrication of high-performance magnets in hybrid cars and wind-turbines. Monazite sands contain around 45 - 48 % cerium, 24% lanthanum, 17% neodymium, 5% praseodymium, along with minor quantities of samarium, gadolinium and yttrium. Europium concentrations tend to be low, in the region of 0.05%, and very low concentrations of the heaviest lanthanides in monazite accord with the term "rare" earth for these elements, with correspondingly high prices. The thorium content of monazite is variable and can be as high as 20 - 30 %, although commercial monazite sands typically contain 6 - 12% thorium oxide. In view of the radioactive nature of thorium, a hazard is posed from waste produced in the processing of rare earth oxides, which contains it.
A controversial REE processing plant is to be built by the Australian based mining company Lynas in Malaysia where it is argued that environmental protection laws are less rigorous than in Australia. The plant is predicted to produce one third of global demand for REEs in two years, hence breaking the Chinese monopoly. It is intended to bury the thorium in concrete, but a better option would be to use the material as a nuclear fuel in place of uranium the price of which has recently risen above $100/pound, in coincidence with the price of crude oil which is now also above $100/barrel.
Now thorium cannot be used directly as a fuel but must first be bombarded with neutrons and "bred" into uranium-233 as the nuclear fuel using slow neutrons, thus avoiding the liquid sodium coolant of uranium-plutonium breeder reactors, and which has the following additional advantages. (1) Plutonium and uranium could still be consumed in a thorium reactor, but without the need to manufacture moreâ plutonium. (2) While uranium-235 and plutonium-239 can be shielded to avoid detection in a suitcase to use that cliche, uranium-233 could not, because it is always contaminated with uranium-232, a strong gamma-ray emitter, which is far less easily concealed as a bomb. There is the final matter of the exact means for obtaining energy from thorium, for example using very large accelerator driven systems (ADS). A more modest alternative is the "Liquid Fluoride Reactor" (LFR), which is described and discussed in considerable detail on the http://thoriumenergy.blogspot.com/ blog, and it appears likely that the LFR may provide the best means to achieve our future nuclear energy programme.
By. Professor Chris Rhodes
Professor Chris Rhodes is a writer and researcher. He studied chemistry at Sussex University, earning both a B.Sc and a Doctoral degree (D.Phil.); rising to become the youngest professor of physical chemistry in the U.K. at the age of 34.
A prolific author, Chris has published more than 400 research and popular science articles (some in national newspapers: The Independent and The Daily Telegraph)
He has recently published his first novel, "University Shambles" was published in April 2009 (Melrose Books). http://universityshambles.com