Central to this argument is the availability of huge reserves of thorium in India. Thorium reserves have been estimated to be between 3,60,000 and 5,18,000 tonnes. The US estimates the “economically extractable” reserves to be 2,90,000 tonnes, one of the largest in the world. Our uranium reserves, by contrast, are estimated to be at a maximum of around 70,000 tonnes.
India currently has 15 commercial power reactors in operation, most of which are pressurised heavy water reactors (PHWR) which use natural uranium. Two Tarapur reactors are boiling water reactors (BWR) which need enriched uranium, which has to be imported.
Together they generate about 3300 MWe (Mega Watt Electrical) of power, about 4 per cent of that generated from all sources. Another six PHWRs are in construction, and along with the two “VVER” Russian built 1000 MWe reactors which use enriched uranium, they would add about 3960 MWe by 2008. The goal is to reach at least 20,000 MWe by 2020.
India's uranium reserves are low. Obtaining enriched uranium for the two Tarapur reactors and VVER type reactors requires the consent of the Nuclear Suppliers Groups countries, including Russia. This is where the agreement with the US is expected to be beneficial to India.
Also central to India's success in achieving these goals, is the harnessing of thorium, for which India has developed a three-stage nuclear programme. India has already developed and tested the technologies needed to extract energy from Thorium, but large scale execution has not yet been possible, mainly because of limited availability of Plutonium.
Stage one is the use of PHWRs. Natural uranium is the primary fuel. Heavy water (deuterium oxide, D2O) is used as moderator and coolant. The composition of natural uranium is 0.7 percent U-235, which is fissile, and the rest is U-238. This low fissile component explains why certain other types of reactors require the uranium to be “enriched” i.e. the fissile component increased.
In the second stage, the spent fuel from stage one is reprocessed in a reprocessing facility, where Plutonium-239 is separated. Plutonium, of course, is a weapons material, which goes towards creating India’s nuclear deterrent.
Pu-239 then becomes the main fissile element, the fuel core, in what are known as fast breeder reactors (FBR). A test FBR is in operation in Kalpakkam, and the construction for a 500 MWe prototype FBR was launched recently by Prime Minister Dr Manmohan Singh.
These are known as breeder reactors because the U-238 “blanket” surrounding the fuel core will undergo nuclear transmutation to produce more PU-239, which in turn will be used to create energy.
The stage also envisages the use of Thorium (Th-232) as another blanket. Th-232 also undergoes neutron capture reactions, creating another uranium isotope, U-233. It is this isotope which will be used in the third stage of the programme. Thorium by itself is not a fissile material, and cannot be used directly to produce nuclear energy. The Kamini 40 MWe reactor at Kalpakkam which became critical in Sept 1996, using U-233 fuel, has demonstrated some of these technologies.
India is currently developing a prototype advanced heavy water reactor (AHWR) of 300 MWe capacity. The AHWRs, which use plutonium based fuel, are to be used to shorten the period of reaching full scale utilisation of our thorium reserves. The AHWR is thus the first element of the third stage. AHWR design is complete but further R and D work is required, especially on safety. It is expected to be unveiled soon and construction launched.
In the third phase, in addition to the U-233 created from the second phase, breeder reactors fuelled by U-233, with Th-232 blankets, will be used to generate more U-233.
The Bhabha Atomic Research Centre has estimated that India's thorium reserves can amount to a staggering 3,58,000 GWe-yr (Giga Watt Electrical - Year) of energy, enough for the next century and beyond
BARC scientists are also looking at other designs, like an advanced thorium breeder reactor (ATBR) which requires plutonium only as a seed to start off the reaction, and then use only thorium and U-233. Here the plutonium is completely consumed and this reactor is thus considered “proliferation resistant”. A Compact High Temperature Reactor also under development at BARC . This reactor is designed to work in closed spaces and remote locations.
Success in harnessing thorium’s potential is thus critical for the India’s future energy security.
India has put in place mechanisms for ensuring safety and security of nuclear facilities. The regulatory and safety systems ensure that equipment at India's nuclear facilities are designed to operate safely and even in the unlikely event of any failure or accident, mechanisms like plant and site emergency response plans are in place to ensure that the public is not affected in any manner. In addition, detailed plans, which involve the local public authorities, are also in place to respond if the consequences were to spill into the public domain. The emergency response system is also in a position to handle any other radiation emergency in the public domain that may occur at locations, which do not even have any nuclear facility.
Regulatory and safety functions of Atomic Energy in India are carried out by an independent body, the Atomic Energy Regulatory Board (AERB). The AERB was constituted on November 15, 1983 by the President of India under the Atomic Energy Act, 1962 to carry out certain regulatory and safety functions under the Act. The regulatory authority of AERB is derived from the rules and notifications promulgated under the Atomic Energy Act, 1962 and the Environmental (Protection) Act, 1986. The mission of the Board is to ensure that the use of ionizing radiation and nuclear energy in India does not cause undue risk to health and the environment.
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