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Thorium
Thorium
● Thorium is a naturally-occurring, slightly radioactive metal.
● Discovered in 1828 by the Swedish chemist Jons Jakob Berzelius.
● Named it after Thor, the Norse god of thunder.● It is found in small amounts in most rocks and
soils.● It is about three times more abundant than
uranium.
Jöns Jacob Berzelius
Characteristics Of Thorium● Pure thorium is a silvery-white metal.
● The physical properties of thorium are greatly influenced by the degree of contamination with the oxide.
● Pure thorium is soft, very ductile, and can be cold-rolled.
● Changes from F.C.C to B.C.C. at 1350 c
● Thorium metal is paramagnetic with a ground state of 6d27s2
Thorium Minerals
● The Mineral ThorogummiteChemistry: (Th, U)2(SiO4)(2 - X)(OH)4X, Thorium Uranium
Silicate Hydroxide.
● The Mineral ThoriteChemistry: (Th, U)SiO4, Thorium Uranium Silicate.
Mining and concentrating● Monazite beach sands are readily mined with conventional placer mining
equipment and procedures. The dredged monazite is admixed with a variety of other minerals, including silica, magnetite, ilmenite, zircon, and garnet. Concentration is accomplished by washing out lighter minerals in shaking tables and passing the resulting monazite fraction through a series of electromagnetic separators, which separate monazite from other minerals by virtue of their different magnetic permeabilities
Thorium As a Nuclear Fuel
● Fertile Material● Fissionable● Most Abundant Nuclear Fuel
● In the thorium cycle, fuel is formed when 232Th captures a neutron (whether in a fast reactor or thermal reactor) to become 233Th. This normally emits an electron and an anti-neutrino(ν) by β−decay to become 233Pa. This then emits another electron and anti-neutrino by a second β−decay to become 233U, the fuel:
Advantages
THORIUM: CLEANER NUCLEAR POWER?
Uranium-based reactors can be retrofitted, bringing major benefits –improving securityallaying environmental concernsimproving economicsThe fuel cycle can also be proliferation resistant, stopping a reactor from producing nuclear weapons-usable plutoniumWith the spent fuel having significantly reduced volume, weight and long-term radio-toxicity, safety margins are increased and operating costs reduced.
Disadvantages
Thorium mining produces waste products like mill tailings which can escape into the environment and as with uranium, thorium mining produces radioactive mining residues.
Besides being relatively costly to produce, the thorium can be difficult to reprocess.
Thorium itself can be difficult to recycle because it is contaminated by highly radioactive Th-228 and despite the lower overall radioactivity.
Owning and handling small amounts of thorium, such as a gas mantle, is considered safe if care is taken not to ingest the thorium -- lungs and other internal organs can be penetrated by alpha radiation.
Exposure to aerosolized thorium can lead to increased risk of cancers of the lung, pancreas and blood. Exposure to thorium internally leads to increased risk of liver diseases.
