Thorium Nuclear fuel of the future :A.P.J Abdul Kalam
Let us introduce a lesser-known member among radioactive materials Thorium. It is perhaps the best solution possible in the future and would be technologically and commercially the best option in another two decades. Thorium, the 90th element in the Periodic Table, is slightly lighter than Uranium. Thorium is far more abundant, by about four timesxxvi, than the traditional nuclear fuel, Uranium, and occurs in a far purer form, too. It is believed that the amount of energy contained in the Thorium reserves on earth is more than the combined total energy that is left in petroleum, coal, other fossil fuels and Uranium, all put together. And information revealed in an IAEA Report (2005) on Thorium fuels indicates that India might have the largest reserves of Thorium in the world, with over 650,000 tonnes. (Note: The IAEA, the International Atomic Energy Agency, is the world's centre of cooperation in the nuclear field. It was set up in 1957 as the world's Atoms for Peace' organisation within the U.N. family.) This is more than one-fourth of the total deposits of Thorium; in comparison, we have barely 1 per cent of the world's Uranium deposits, which is currently being put to effective use, our having opted for the closed fuel cycle technology. Thorium has many other advantages. It is estimated that Thorium may be able to generate (through Uranium-233 that could be produced from it) eight times the amount of energy per unit mass compared to (natural) Uraniumxxvii. In the much debated issue of waste generation also, Thorium has a relative advantage. It produces waste that is relatively less toxic due to the absence of minor actinides (that are associated with Uranium).
At the same time, it is acknowledged that the long-lived high-level waste from Uranium, especially in light of the Indian strategy of adopting the closed fuel cycle involving reprocessing for the recovery of Plutonium and Uranium, can be effectively managed using technologies available today. Indian nuclear experts tell us that the relatively small volumes of such waste (long-term storage space of less than a quarter of the size of a football field is adequate for the estimated waste from a 1000 MWe plant) can be safely stored after vitrification for hundreds of years without causing any risk to the environment or the people.
One question that crops up is, why then has Uranium rather than Thorium become the popular choice for nuclear energy programmes across the world? There are two reasons: one is technological and the other is historical.
The technological reason stems from the simple fact that at first one needs to produce Uranium-233 from Thorium, and for this, reactors based on the naturally available nuclear fuel material, Uranium-235, are required. In addition, the recovery of Uranium-233 by large-scale reprocessing of irradiated thorium, as well as the likely presence of hard gamma emitting Uranium-232, pose certain practical hurdles. But according to experts, all these can be overcome technologically.
The second and the historical reason why Thorium has lagged behind in the ladder of development, comes from its advantage of being able to provide Thorium-based fuel, as seen from the context of the relatively unstable geopolitical conditions which is that Thorium cannot be weaponised. Unlike Uranium, which is always on a tight-rope walk between being a power source and finding destructive applications, Thorium bombs just cannot be made. Here history steps in. It must be remembered that much of the current civil nuclear applications are direct offshoots of the military nuclear technologies of the Cold War period. So, the first significant outcome of nuclear technology was the Manhattan Project during the Second World War, which ultimately culminated in the Hiroshima and Nagasaki bombing of 1945 by the U.S.
A nuclear weapon is different from a nuclear plant, as in the former there is no need to control or slow down the reactions that lead to a catastrophic energy release in a short time interval which is the essence of a bomb. However, a nuclear plant needs moderation of the reaction to sustain a steady but controlled release of energy. It was only by the end of 1951 that some noteworthy work was done in controlled nuclear power generation at the EBR-1 experiment in Idaho to produce 100 KW of nuclear power. This weapon first approach to nuclear technology led to the fact that there was little focus on developing methods to energise from Thorium, which is non-weaponisable, and a larger focus on Uranium, which can be weaponised.
But now, being the largest owner of Thorium, and also being amongst the nations which will see the highest surge in power demand with its growth, the opportunity is for India to pursue its existing nuclear programme with a special focus on research and development on the Thorium route as the long term sustainable option, which we are already undertaking. For this purpose, it is imperative to continue to implement the current Indian plan of making use of the uranium and plutonium-based fuel cycle technologies as well as irradiate larger amounts of Thorium in fast reactors to breed Uranium-233 fuel as it graduates to the Thorium-based plants. It is noteworthy that the Indian plan for an advanced heavy water reactor (AHWR) is an important step to launch early commencement of Thorium utilisation in India, while considerable further efforts to use Thorium in both thermal and fast reactors would be essential to harness sustainable energy from Thorium-generated Uranium-233.
Various technologies for Thorium-based plants are already being developed and deployed on a test basis across the world including in India, which have a promising future. These include first breeding it to fissile Uranium-233 isotope in the conventional reactors or through the revived interest in technologies like the Molten Salt Reactors (MSR) which use salts to trap the fissile material and do not react with air or burn in air or water. In this technology, the operational pressure is near the ordinary atmospheric pressure, and hence the cost of construction is low and there is no risk of a pressure explosionxxviii.
A significantly large quantity of highly active nuclear material exists, and will continue to exist in the form of nuclear armaments which was the mother programme of the nuclear energy programme. In 2010, there were about 22,000 nuclear warheads spanning at least nine countries of the world, and 8,000 of them are in active state, carrying a risk far greater than controlled nuclear power reactors. If the argument of risk is to be used to eliminate the peaceful energy generation programme, then the nuclear opposition factions must first direct their efforts at Washington and Moscow, the owners of 90 per cent of the world's nuclear warheads, to disband their nuclear arsenal which is, by design, intended to be hostile. Would that happen? Unlikely, at least in the foreseeable future. Our aim should be to minimise the risks associated with nuclear power.
The power of the nucleus is mighty and the future of humanity lies in harnessing it in a safe and efficient manner. In the years to come, it will fuel not only our earth-based needs but also our space missions and perhaps even our civilisation's reach to other planets for habitation. Our current nuclear projects will expand into better and safer materials, like Thorium, and later on, into better reactions like fusion, which once completely developed, will be able to generate hundreds of times more of power than current fission methods. Affordable, clean and abundant energy provided by nuclear sources is our gateway to a future that is healthy, learned and connected a future that will span deep into space and crosses the boundaries of current human imagination.
The Hindu : Opinion / Op-Ed : Nuclear power is our gateway to a prosperous future
