Journalist, Oliver Tickell, author of the Kyoto2 climate initiative, (1) editor of the Nuclear Pledge website (2) and Green Party candidate for Oxford City Council in three elections, has published a new briefing on Thorium reactors.
A number of commentators have argued that most of the problems associated with nuclear power could be avoided by both, using thorium fuel in place of uranium or plutonium fuels and using ‘molten salt reactors’ (MSRs) in place of conventional solid fuel reactor designs. The combination of these two technologies is known as the Liquid Fluoride Thori um Reactor or LFTR, because the fuel is in form of a molten fluoride salt of thorium and other elements.
The briefing examines the validity of the optimistic claims made for thorium fuel, MSRs and the LFTR in particular, and finds that they do not stand up to critical scrutiny – these technologies have significant drawbacks including: very high costs; marginal benefits for a thorium fuel cycle over uranium; serious nuclear weapons proliferation hazards; the danger of both routine and accidental releases of radiation, mainly from continuous ‘live’ fuel reprocessing in MSRs and the very long lead time for significant deployment of LFTRs of perhaps 50 years – rendering it irrelevant in terms of addressing current or medium term energy supply needs.
The thorium-uranium fuel cycle has some advantages over the dominant uranium-plutonium cycle, in terms for example, of the reduced production of long-lived actinides and somewhat diminished radio -toxicity overall. However, it also creates new hazards of its own. As far as radioactive fission products are concerned, there is little to choose between the two.
Thorium reactors do not produce plutonium. But an LFTR could (by including 238U in the fuel) be adapted to produce plutonium of a high purity well above normal weapons-grade, presenting a major proliferation hazard. Beyond that, the main proliferation hazards arise from the need for fissile material (plutonium or uranium) to initiate the thorium fuel cycle, which could be diverted, and the production of fissile uranium 233U.
LFTRs are theoretically capable of a high fuel burn-up rate, but while this may indeed reduce the volume of waste, the waste is more radioactive due to the higher volume of radioactive fission products. The continuous fuel reprocessing that is characteristic of LFTRs will also produce hazardous chemical and radioactive waste streams, and releases to the environment will be unavoidable. Spent fuel from any LFTR will be intensely radioactive and constitute high level waste. The reactor itself, at the end of its lifetime, will constitute high level waste.
The UK’s National Nuclear Laboratory (NNL) believes that considerable research, development and testing lies ahead before thorium fuels will be ready for operational use. As the NNL states, “Thorium reprocessing and waste management are poorly understood. The thorium fuel cycle cannot be considered to be mature in any area.” It estimates that 10-15 years work is required before thorium fuels will be ready for use in current reactor designs, and that their use in new types of reactor is at least 40 years away. (3)
(3) Thorium: Not Green, Not Viable and Not Likely, Oliver Tickell, June 2012