Nuclear fuel resources thorium

The development of thorium-based nuclear power cycles still faces various problems and requires much more R D to be commercialised. As a nuclear fuel, thorium could play a more important role in the coming decades, partly as it is more abundant on Earth than uranium and also because mined thorium has the potential to be used completely in nuclear reactors, compared with the 0.7% of natural uranium. Its future use as a nuclear source of energy will, however, depend greatly on the technological developments currently investigated in various parts of the world and the availability of and access to conventional uranium resources. 

The advantage of the Th-U fuel cycle is that it increases nuclear energy resources considerably because thorium is about three times more abundant on earth than uranium and almost as widely distributed. In combination with the uranium fuel cycle it could more than double the lifetime of the uranium resources by running the reactors at a high conversion rate (-1.0) and recycling the fuel. Very rich thorium minerals are more common than rich uranium minerals. The presence of extensive thorium ores has motivated some countries (e.g. India) to develop the Th-U fuel cycle. 

Estimates of world energy resources are summarized. It is pointed out that the great effort to exploit nuclear energy can be justified only if it is directed toward a full utilization of uranium and thorium. Without breeding, nuclear fuels will only supply energy for a few decades in the future energy-hungry world. 

Research and development activities for thorium fuel cycles have been conducted in Germany, the USA, India, Japan, Russia and the UK during the last 30 years at a much smaller scale than uranium and uranium-plutonium cycles. Nowadays, India, in particular, has made the utilisation of thorium a major goal in its nuclear power programme, as it has ambitious nuclear expansion plans and significant indigenous thorium resources. 

The elimination of burnable poison and high fuel bum-up contribute to a more efficient use of uranium resources. Various fuel options available for the FBNR broaden the available resource base, which could also include plutonium from dismantled nuclear weapons and the abundant thorium available in countries like Brazil and India. 

Nuclear reactors can be designed on the basis of their fuel cycle such that they breed more fissile nuclides than what they use. Breeder reactors can utilize uranium, thorium, and plutonium resources more efficiently. There are two types of breeder reactors (1) fast neutron spectmm breeder and (2) thermal neutron spectmm breeder reactors, which are designed based on (99.2% natural abundance) and Th (100% natural abundance), respectively. Fertile nuclides and Th capture neutrons and trans-form, respectively, to fissile nuclides Pu and U. Through this process, which is known as breeding, the reactor produces more fissile nuclides than what it consumes. Fast-breeder reactors (FBRs) can also be used in order to transmute the long-lived... 

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