by ANTHONY TREWAVAS
Nuclear power need not be a threat, says Anthony Trewavas
Use of thorium instead of uranium in reactors can allay virtually all public concern over weapons proliferation, radioactive pollution, toxic waste and fuel that is costly and complicated to process.
Thorium is the most abundant, most readily available, cleanest and safest energy source on earth; yet it remains unknown by both the public and politicians. Novel reactor design, the liquid fuel thorium reactor (LFTR), uses thorium fluoride as both coolant and fuel. It has enormous advantages over the use of uranium in nuclear power; it is the fuel of the future.
Thorium is as abundant as lead and four times more abundant than uranium. It is barely radioactive, with a half-life longer than the age of the universe and thus transport safety is not an issue. Major reserves are found in friendly countries like Australia, the United States, Brazil and there are seams in Wales and Cornwall. It occurs as only one isotope and thus avoids the necessary and costly enrichment processes that are required for uranium.
The reactor needs small amounts of start-up radioactivity. An alternative design uses a small proton accelerator to initiate nuclear reaction. Uranium reactors require ten times the amount of priming material to initiate reaction. The thorium reaction is self-sustaining and, apart from small annual additions of thorium fluoride, feeds itself to completion. One tonne of thorium can produce as much energy as 200 tonnes of uranium and 3.5 million tonnes of coal. Energy generated by an LFTR is cheaper than coal.
Some 99 per cent of the thorium is used up in the LFTR. Current uranium reactors use less than 1 per cent of uranium before costly transport and reprocessing is necessitated. The 1 per cent thorium waste can be processed and sold after ten years and after 100-300 years is at or below background level, unlike uranium waste that must be stored for 300,000 years.
The thorium nuclear reaction does not produce plutonium as a by-product, unlike uranium reactors, and cannot be used for weapons or weapons proliferation. The first thorium reactor was designed, built and operated in the US in the Sixties, but its failure to generate plutonium required for nuclear warheads was the primary reason that further research was cancelled and its proponents sacked. Had research not been abandoned, it is estimated that the US would have been self-sufficient in energy by 2000.
Thorium is the closest thing to a truly green energy. The known reserves of thorium are sufficient to fuel the earth for many thousands of years. Although environmentalists claim wind and solar as green and clean, these always require fossil fuel back-up emitting CO2 because of variability in the source. The LFTR uses far less concrete and steel/kWhr than required by wind turbines and its operating cycle generates no carbon dioxide.
The safety of LFTR is unparalleled. There is zero risk of meltdown, any untoward event such as an earthquake can be controlled by a freeze plug that melts and drains the material into an underground chamber, where it is air cooled. None of this requires electricity. By not using pressurised water, the accumulation of hydrogen gas that caused the problem at Fukushima is avoided.
LFTRs operate at atmospheric pressure, with little possibility of explosion or containment breach. The radioactive products remain attached and are chemically bonded to the fluoride salt preventing spread of radioactive material. LFTRs operate at high temperature, allowing use of higher-efficiency, reheat power cycles employing nitrogen or helium as the working fluid rather than steam to drive turbines, thereby raising efficiency from 35 to 50 per cent.
Development of thorium reactors is underway in China, India, the US, Israel and Russia. Norway is considering using thorium-generated electricity as a replacement for oil. A recent report to the Westminster government exhibited typical, conservative unwillingness to consider further research into thorium, by favouring the present uranium reactor construction with its disadvantages. This report signally failed to recognise the concerns of the populace about present uranium nuclear technology. A five to ten-year research programme on thorium to fill minor technical gaps and construct a reactor prototype would cost less than one gas-fired power station.
Societies that expand and improve the efficiency of their energy supplies supersede those that don’t. The aim of both Westminster and Holyrood has been the generation of expensive unreliable electricity instead of promoting abundant supplies of cheap reliable energy and facilitating its distribution and consumption. More cheap energy equals more cheap power equals more wealth. The political establishment in all parts of the UK has championed policies that do the complete opposite and will most surely accelerate economic decline. Attitudes to thorium become a touchstone that mark out those optimistic countries and populations that grasp the future from those who are fearful of it and become a backwater of history.
• Professor Anthony Trewavas chairs Scientific Alliance Scotland