THORIUM IN INDIA

Assignment On

Resource Geography

THORIUM

Submitted By:

Laltanpuia

Roll No – 22

Dept. Of Geography, Mizoram University

    Thorium is a source of nuclear power. There is probably more untapped energy available for use from thorium in the minerals of the earth's crust than from combined uranium and fossil fuel sources. Much of the internal heat the earth has been attributed to thorium and uranium. When pure, thorium is a silvery white metal which is air-stable and retains its luster for several months. When contaminated with the oxide, thorium slowly tarnishes in air, becoming grey and finally black. Thorium oxide has a melting point of 3300°C, the highest of all oxides. Only a few elements, such as tungsten, and a few compounds, such as tantalum carbide, have higher melting points. Thorium is slowly attacked by water, but does not dissolve readily in most common acids, except hydrochloric. Powdered thorium metal is often pyrophoric and should be carefully handled. When heated in air, thorium turnings ignite and burn brilliantly with a white light. Thorium is named for Thor, the Scandinavian god of war. It is found in thorite and thorianite in New England (USA) and other sites.

    THORIUM DEPOSITS

    Some common minor primary constituents of igneous rocks carry uranium and thorium in isomorphous substitution for and other elements.  Monazite, apatite, zircon and sphene are some of the most abundant minerals belonging to this category.  Most of these minerals are resistant to alteration, but they differ greatly in their resistance to attrition during their transportation with clastics.  Monazite, apatite and xinotime are most easily reduced by attrition, but under favorable conditions these minerals become enriched in sands and gravels which have been transported short distances.  They are found frequently in heavy mineral resistate fraction of terrestrially deposited clastics.  Hence stream and beach monazite-bearing placers are found in many parts of the world.  Zircon, which also carries a large portion of U and Th contents of felsic rocks, is a common constituent of the resistate fraction of all kinds of clastic sediments.  These resistant minerals (monazite, apatite, xinotime and zircon) may be removed from erosional terranes of the igneous rocks and become concentrated in placer deposits in environments where rock destruction by decomposition is predominant over that by disintegration, viz. the tropical climatic zones.

    The thorium content of the minerals contained in these placers is considerably greater than the uranium content; therefore the deposits are classified primarily as thorium-­bearing placers.

    Monazite is the chief source of thorium in the world.  Though it is a constituent of some granites and pegmatites, such sources are not economically workable.  Monazite is concentrated by weathering into economically workable deposits in beach sands in the coastal tracts of Australia, Brazil, Ceylon, Malaysia and India.  India possesses the largest deposits of monazite in the world.  Recent indications are that in the near future, thorium would emerge as a fission fuel of greater potential than thorium.

    In India monazite is found in the coastal tracts of Cuttak and Ganjam districts of Orissa where the thickness of the placer is about 30 cm with a monazite content of 2.5 percent.  Minor occurrences have been noticed between Chilka Lake and Chicacole River also.

    In Andhra Pradesh thick ilmenite and monazite placers are found around Vishakhapatnam and Bhimunipatnam.  The beach sands of the coastal tracts of Kerala and Tamil Nadu are also very rich in monazite.  They also contain ilmenite and rutile.  Monazite bearing sands are best developed along the beaches of the southwest coast of India between Quilon and Kanyakumari (Lipuram, Pudur, Kovalam, Varkala and Neendakarai) and between Chowghat and Ponnani.  On the east coast of India, monazite concentrations are not as good as on the western and southwestern coasts, nevertheless small deposits are found along the Vishakhapatnam and Tanjore coasts. The monazite content of placers is rarely more than 3%.  It appears that the maximum concentration of U and Th in placer type deposits are about 70 and 3000 ppm of sediment respectively, and the average concentrations are probably about 2 and 60 ppm respectively.  Sands on the Flo rida coast are reported to contain 0.09% monazite, beach sands of India average 2-5% monazite.

    Elsewhere in the country black sand deposits occur in the coastal tracts of Waltair, Bimlipatnam and Narasipatnam.

THORIUM RESERVES IN INDIA

    In year 2010-2011, India met a deficit of 8.5% on base electricity load. For a country like India, it might look a small number. However, this is above and over the fact that 300 million people in India are already outside the electricity grid (out of 1.4 billion global). Hence, along with expanding the power grid the country actively needs to go further in producing electricity.

    Historically, India was kept outside the Nuclear Proliferation Treaty from 1970 because of its nuclear weapon development program. Due to these trade restrictions, its nuclear program went through a slow evolution. However, at the same time, it was able to develop its own nuclear reactor designs and aware of its Thorium reserves, it has been uniquely developing Thorium nuclear reactors.

    Of the currently known world thorium reserves, India has a large number of share - ranging from 25-30% of the total of 1,160 thousand tonnes. This coupled with the growing need for energy and restrictions on Uranium trade had made India's inclination towards Thorium reactors obvious. Its main source is the Monazite deposits, which occur essentially in the entire peninsula. There are also inland resources in the Ranchi plateau. Apart from there are scattered deposits in the Gujrat region, Bihar and inner Tamil Nadu. However, the bottom line remains that the estimation of the distribution of these deposits demands considerable improvements and there is large incentive for further exploration.

   

    India has recently demonstrated world's first prototype of reactor using this fuel. Although, the title of a "safer" fuel remains controversial, India believes it to be a safer fuel. "The basic physics and engineering of the thorium-fuelled Advanced Heavy Water Reactor (AHWR) are in place, and the design is ready," said Ratan Sinha, director of Bhabha Atomic Research Center (BARC) in Mumbai.

    Energy demand of the current world is only going to get higher. With more and more industrialization and people, energy demand is going to be higher than ever. With world's manufacturing sector moving into India and China, there is an immense amount of energy need in Asia's sphere. There has also been a dramatic increase in price of coal and petroleum in recent years especially in India. In such a scenario, a constant price offered by abundant Thorium fuel and Nuclear Energy can be nothing short of a boon for a country like India. India plans to expand its nuclear sector to provide about 63GW of power by 2032 and gradually increase it to 25% by 2050.

    Though, it looks like an ideal picture, India still has to successfully demonstrate a working Thorium based reactor, being able to deal with nuclear waste disposal with minimum environmental affect, and built successfully an energy grid to support this supply.

References:

    Bookins, D.G., (1981) : Earth Resources; Energy and the Environment, Charles E. Morril     Co., Coloumbus.

    Holechek, J.L., (1990) : Natural Resources : Ecology, Economics and Policy, Prentice Hall,     New Jersey.

    http://www.webelements.com/thorium

    http://www.rsc.org/periodic-table/element/90/thorium

    http://large.stanford.edu/courses/2012/ph241/bordia1