Posted on 05/17/2011 1:33:00 PM PDT by ckilmer
Why is nobody talking about safe nuclear power? By Julian Cribb - posted Wednesday, 4 May 2011 Sign Up for free e-mail updates!
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. Advertisement
It is safe from earthquake, tsunami, volcano, landslide, flood, act of war, act of terrorism, or operator error. None of the situations prevailing 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, USA, 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 byproduct 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 environment and public. 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. Advertisement
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. 19 of these have taken human life or caused over $100m 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 and a recent pledge by China to start – why is almost nobody seeking to commercialise this proven source of clean energy?
These are not easy questions to answer – but 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 byproduct. 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. Advertisement
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 R&D 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, especially the renewables – that is for engineers, the electricity market and policymakers to sort out. But it must now be seriously considered as an option in our future energy mix.
Also, Geoscience Australia estimates Australia has 485,000 tonnes of thorium, nearly a quarter of the total estimated world reserves. Currently they are worthless - but could be worth billions.
There is a strong argument for Australia 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.
they can be made small enough to power an aeroplane
As it happens, I was involved with the nuclear powered aircraft project in the late 1950s (guidance, not propulsion), so I'm familiar with the problems of putting a reactor in an airplane. To begin with, reactors must be shielded, and shielding is heavy. Most of the designs for nuclear powered aircraft had a heavily shielded crew compartment, and just enough shielding on the reactor that, when it was on the ground, you could approach it in a shielded tractor. However, that meant that the airframe was bombarded by lots of neutrons, which created dislocations on the crystal structure. That would rapidly lead to crack growth, meaning the airframe would have a short useful life, and would be radioactive. Big disposal problem. Another problem was that the temperature possible in a nuclear reactor is limited by the properties of the reactor structure. No matter what you do, this is going to be lower than the gas temperature in a fossil-fueled jet engine. Lot of power in the reactor, but transferring that to a jet exhaust is tough. The laws of thermodynamics work against you (nuclear powered rockets have the same problem).
In short, a nuclear powered airplane was a loser back then, and I don't think going to a thorium reactor is going to change that.
For stationary power plants, though, and possibly for ship-board power plants, we ought to be investigating the thorium reactor. If necessary, we need to get away from the not-invented-here types in the Department of Energy.
How does a thorium reactor compare with a modular pebble bed reactor?
Who does one pay for the fuel cost of wind and solar?
....
The costs for solar and wind are capital costs and maintenance costs
Fuel costs for thorium are a tiny $0.00004/kWh versus...wind appx. 14 cents /kWh; solar thermal about 26 cents/kWh and solar photovoltaic a hefty 40 cents/kWh.
Why would you compare "fuel costs" of thorium to capital costs of solar and wind? Does thorium not have any capital cost?
Of course, this is one of the reasons the Greenies cite when they're smearing coal (radioactive elements...).
The pebble bed reactor uses uranium that's encapsulated in "pebbles." I'm not sure about the exact size, but think of them as tennis balls or softballs. In operation, an inert gas such as helium is passed through the "bed" to transfer the heat to a turbine or heat exchanger. I don't know whether thorium can be used in place of uranium. In any case, the "pebble bed" refers to a structure, not to the fissile material used.
All the discussion of thorium reactors revolves around liquid thorium fluoride. That's probably not the only way to utilize thorium in a reactor, but that's the way it's been looked at in the past. This approach seems to have many advantages over the way we now build uranium-fueled reactors, so should be investigated.
Meanwhile, the scientifically illiterate, sentimental Gaia-worshipping lawyers and career politicians are locking America into their fantasy of wind and solar power.
It is. The Chinese have been buying up mineral rights across the mountain west.
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