Dialogue | Does thorium offer any advantages over uranium as a nuclear fuel?
Thorium has been proposed as an alternative to uranium because of its abundance in nature and the hope that it might pose fewer waste and safety risks. In principle, thorium could be used in a variety of reactors, including conventional light-water reactors used in the United States, but it cannot sustain a nuclear chain reaction by itself. It must be combined with a fissile material such as enriched uranium, uranium-233 (an isotope created from thorium), or plutonium. However, the Department of Energy has found that reactors fueled with thorium and uranium do not provide any clear advantages over uranium-only reactors in terms of waste management, proliferation risk, safety, economics, or sustainability.
Liquid fluoride thorium reactors (LFTRs), which use a fuel made of molten salt, have been proposed as significantly safer than current-generation reactors, but serious safety issues associated with the retention of fission products in the fuel may not be resolved. LFTRs also present proliferation and terrorism risks because they involve the continuous “reprocessing” of the spent fuel to separate out uranium-233, which could be used in a nuclear weapon. Moreover, disposal of the used fuel could pose a major challenge; an experimental LFTR that operated at Oak Ridge National Laboratory in the 1960s still has highly radioactive spent fuel on site that is proving very costly and difficult to clean up.
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