FARMINGTON HILLS, Mich. () -- Thorium, one of the "rare earth metals," is an alternative to uranium as fuel for the construction of nuclear reactors designed for the purpose of producing electricity.
Thorium was, in fact, tested for this purpose at the very beginning of the design of nuclear power plants for generating electricity for powering submarines. It was used in the fuel for the world's first land sited nuclear power plant located at Shippingport, Pennsylvania. That first plant was built under the aegis of the "Atoms for Peace" program championed by then President Eisenhower.
The reasons for trying to use thorium were as urgent in 1955, as they are critical now. They are, simply, to reduce sharply both the amount of radioactive "waste" generated by nuclear power plants and to impair the capability of nuclear power plants to produce readily extractable weapons grade fissile materials such as plutonium-239 and uranium-235.
Thorium's backers make a compelling case for a running 'switch' from uranium based fuel to thorium based fuel in existing Russian reactors and in the construction of new reactors with a mainly thorium based fuel in place of uranium.
Thorium has been determined to be three to four times more abundant than uranium in nature. The world's total economically extractable reserves have been recently estimated at 1,200,000 tonnes (metric tonne units). Australia with 300,000 tonnes of reserves, leads the world in this category, followed by India (290,000 tonnes), Norway (170,000 tonnes), the U.S. (160,000 tonnes), Canada (100,000 tonnes), South Africa (35,000 tonnes) and Brazil (16,000 tonnes), with all others totalling 95,000 tonnes.
The most common ore of thorium, the phosphate mineral, monazite, which contains up to 12% of thorium oxide, also contains the economically extractable other rare earth metals, cerium, lanthanum, neodymium, yttrium and iridium. An immediate benefit therefore of producing thorium would be the creation of additional supplies of strategic materials for:
- Chemical catalysis (cerium: used in the petroleum industry and emissions control catalysts for gasoline and diesel fueled vehicles);
- Battery manufacturing (lanthanum: used in the production of nickel metal hydride rechargeable batteries for hybrid vehicles and portable electronic devices);
- Small powerful magnets (neodymium: used to make the magnets used in miniature electric motors such as the 41 of these used in a typical automobile), and;
- High temperature corrosion resistant alloys (iridium: used in surgical devices, thermocouples and automotive emission catalysts).
These other rare earth metals are no longer mined in the U.S. due to the fact that the mining of monazite for them produces a "waste" product of thorium!
The Southwest Biodiversity Institute, an environmental organization, has in fact led the charge that stopped rare-earth mining in the U.S. during the last 10 years. The rare earth metals that we do use in the U.S. are today imported principally from the Peoples Republic of China.
Thorium-232, the isotope that makes up 99%+ of natural thorium is mildly radioactive but its half-life in three times the life of the earth. The main feature of the nuclear chemistry of thorium that makes it attractive is the fact that thorium-232 can be converted by bombardment with slow neutrons into uranium-233, which is not only fissile, but also more efficient at producing further slow neutrons to maintain a chain reaction than U-235, the "natural isotope," used for weapons and reactor fuel. Additionally it must be noted that U-235 makes up only 0.7% of the total of natural uranium, which is primarily non-fissile uranium-238.
Reactor fuel is today entirely made from uranium (enriched to between 8% and 20 % in U-235 in processes developed during WWI for the production of "bomb grade-up to 80% U-235") and plutonium (Pu-239, which is chemically extracted from spent fuel and then fed back into a new reactor cycle), because, historically, these reactors were designed to "breed" plutonium, ostensibly so that the reactors would actually produce more fuel than they consume. In fact this focus on the use of highly enriched uranium as a fuel to make plutonium has resulted in a steady supply of weapons grade plutonium from which nearly all "modern" nuclear weapons are made. Thorium like uranium can be mixed with plutonium to make reactor fuel, but thorium has two major advantages over uranium:
- Thorium can be used to "burn" up existing stocks of weapons grade plutonium, and;
- Thorium reactors can be designed so that they do not produce weapons grade fissile material.
Thorium can be blended with weapons-grade plutonium to make fuel for nuclear reactors that convert the plutonium to a grade not suitable for the manufacture of fission weapons. This process allows us to use and therefore reduce or eliminate the radioactive thorium waste from rare earth processing thus allowing more rare earths to be produced for environmentally friendly uses such as emissions control catalysts and the batteries for hybrid vehicles. In addition this allows us to make a civilian-use asset out of weapons grade plutonium from the decommissioning of weapons rather than a dangerous liability.
The projected cost for disposing of weapons grade plutonium by methods in use today is estimated at $2-$5 billion per tonne. The United States and Russia have most of the weapons-grade plutonium in the world, and have mutually agreed to reduce their inventories. It has been stated that making new reactor fuel from thorium/weapons-grade plutonium is the fastest, most effective and cheapest means to dispose of the weapons-grade plutonium. Both the Russian and the U.S. governments are developing programs that emphasize thorium for this purpose.
In addition the world is awash in plutonium produced in civilian breeder reactors (there are a total of 1,700 tonnes of reactor-grade [mixed isotopes] plutonium in existence). Some of this reactor grade plutonium has already been separated and stored as spent fuel. Unfortunately this material could be used to make very inefficient but very dirty nuclear weapons. Thorium/reactor-grade plutonium fuel may be a more economical and effective way to dispose of reactor-grade plutonium than the current recycling process used. For example, the resultant ash from 'burning' thorium plutonium is 1/3 less volume than that generated today.
There is now one American company working actively in the thorium/uranium fuel approach to reducing the proliferation of nuclear weapons, Novastar Resource, Ltd. [OTCBB:NVAS], originally a mining company focusing on thorium, other rare earth metals and platinum group metals. Novastar has recently acquired Thorium Power, a Washington D.C.-based company that has developed nuclear fuel designs to stop the production of weapons-grade plutonium and eliminate existing plutonium stockpiles from both weapons-grade and spent reactor-grade plutonium.
Reactors have been built and are operating on thorium/uranium fuel in India and in Russia. It is the abundance of uranium and the desire for weapons that prevents thorium/uranium-fuelled reactors from becoming commonplace. I hope that the Iranian crisis wakes people up in the world's capitals to the clear and present danger being presented. It is important to not brush off this approach to reducing proliferation by citing environmental constraints or the need for "more research." All the outstanding environmental, political, chemical and engineering problems of proliferation can be solved if they are looked at holistically instead of myopically.