This article was first published in the Canberra Times.
In the wake of the Fukushima nuclear disaster, the most extraordinary thing is the lack of public discussion and the disturbing policy silence - here and worldwide - over safe nuclear energy.
Yes, it does exist.
There is a type of nuclear reactor which cannot melt down or blow up, and does not produce intractable waste, or supply the nuclear weapons cycle. It's called a thorium reactor or sometimes, a molten salt reactor - and it is a promising approach to providing clean, reliable electricity wherever it is needed.
It is safe from earthquake, tsunami, volcano, landslide, flood, act of war, act of terrorism, or operator error. None of the situations at Fukushima, Chernobyl or Three Mile Island could render a thorium reactor dangerous. Furthermore thorium reactors are cheap to run, far more efficient at producing electricity, easier and quicker to build and don't produce weapons grade material.
The first thorium reactor was built in 1954, a larger one ran at Oak Ridge in the United States from 1964-69, and a commercial-scale plant in the 1980s - so we are not talking about radical new technology here. Molten salt reactors have been well understood by nuclear engineers for two generations.
They use thorium as their primary fuel source, an element four times more abundant in the Earth's crust than uranium, and in which Australia, in particular, is richly-endowed. Large quantities of thorium are currently being thrown away worldwide as a waste by-product of sand mining for rare earths, making it very cheap as a fuel source.
Unlike Fukushima, these reactors don't rely on large volumes of cooling water which may be cut off by natural disaster, error or sabotage. They have a passive (molten salt) cooling system which cools naturally if the reactor shuts down. There is no steam pressure, so the reactor cannot explode like Chernobyl did or vent radioactivity like Fukushima. The salts are not soluble and are easily contained, away from the public and environment. This design makes thorium reactors inherently safe, whereas the world's 442 uranium reactors are inherently risky (although the industry insists the risks are very low).
They produce a tenth the waste of conventional uranium reactors, and it is much less dirty, only having to be stored for three centuries or so, instead of tens of thousands of years.
Furthermore, they do not produce plutonium and it is much more difficult and dangerous to make weapons from their fuel than from uranium reactors.
An attractive feature is that thorium reactors are ''scalable'', meaning they can be made small enough to power an aeroplane or large enough to power a city, and mass produced for almost any situation.
Above all, they produce no more carbon emissions than are required to build them or extract their thorium fuel. They are, in other words, a major potential source of green electricity. According to researcher Benjamin Sovacool, there have been 99 accidents in the world's nuclear power plants from 1952-2009. Of these, 19 have taken human life or caused over $100million in property damage.
Such statistics suggest than mishaps with uranium power plants are unavoidable, even though they are comparatively rare. (And, it must be added, far fewer people die from nuclear accidents than die from gas-fired, hydroelectric or coal-fired power generation.)
But why have most people never heard of thorium reactors? Why is there not active public discussion of their pros and cons compared with uranium, solar, coal, wind, gas and so on? Why is the public, and the media especially, apparently in ignorance of the existence of a cheap, reliable, clean and far less risky source of energy? Above all - apart from one current trial of a 200MW unit by Japan, Russia and the US - why is almost nobody seeking to commercialise this proven source of clean energy? The situation appears to hold a strong analogy with the stubborn refusal of the world's oil and motor vehicle industries for more than 70 years to consider any alternative to the petrol engine, until quite recently.
Industries which have invested vast sums in commercialising or supplying a particular technology are always wary of alternatives that could spell its demise and will invest heavily in the lobbying and public relations necessary to ensure the competitor remains off the public agenda.
It is one of the greatest of historical ironies that the world became hooked on the uranium cycle as a source of electrical power because those sorts of reactors were originally the best way to make weapons materials, back in the '50s and '60s. Electricity was merely a by-product. Today, the need is for clean power rather than weapons, and Fukushima is a plain warning that it is high time to migrate to a safer technology. Whether or not it ever adopts nuclear electricity, Australia will continue to be a prominent player as a source of fuel to the rest of the world - be it uranium or thorium.
So why this country is not doing leading-edge research and development for the rapid commercialisation of safe nuclear technology is beyond explanation. There is good money to be made both in extracting thorium and in exporting reactors (we bought our most recent one from Argentina).
As a science writer, I do not argue the case for thorium energy over any other source, but it must now be seriously considered as an option in our future energy mix. Geoscience Australia estimates Australia has 485,000 tonnes of thorium, nearly a quarter of the total estimated world reserves. Currently they are worthless but there is a strong argument to invest some of our current coal and iron ore prosperity in developing a new safe, clean energy source for our own and humanity's future.
Julian Cribb is a Canberra science writer.
Editor's Note: note text.