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House of Assembly - Fifty-First Parliament, Second Session (51-2)
2007-11-14 Daily Xml
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NUCLEAR WASTE

Mrs PENFOLD (Flinders) (15:34): Since 3 May 2006, when I spoke of hearing Mr Wilson da Silver on the ABC Science Show, I have mentioned in this house the need to take the mineral thorium seriously to help us to take back the nuclear waste safely, particularly plutonium, created from the sale of our uranium. I believe that we are morally obliged to take back these wastes to ensure a safer world, as currently, our uranium, after use, can easily find its way to less stable countries where it could be used to devastate us and the people of the world far more efficiently than climate change ever will.

On 7 March 2007, I recommended the article 'New Age Nuclear' by Tim Dean in the April 2006 issue No. 8 of Cosmos magazine. I heard almost nothing about thorium since then until, to my amazement, I opened The Advertiser Review of Saturday 3 November 2007 to page 2 under 'Can You Believe It?' with Professor Stephen Lincoln, entitled 'Uranium alternative: A safer, more plentiful nuclear fuel is in our backyard'. In a box headed 'The “other” nuclear fuel' three points were made as follows:

There is three times more known thorium than uranium. A quarter of these reserves are in Australia.

Thorium cannot sustain a nuclear chain reaction alone, making it a safer fuel and reducing its usefulness as a weapon.

The radioactive waste produced by thorium has a shorter life span than normal uranium fuels.

I am delighted that Professor Lincoln is a professor of chemistry at our very own University of Adelaide and I note that he is the author of Challenged Earth which I have yet to find time to read. However, I want to quote his article, which was buried on page 2 of the Review, in order to draw it to the attention of a broader audience than it probably found there in the hope that the government (both state and federal) will invest in thorium research. Hopefully, they might reconsider taking back our nuclear waste and help replace nuclear power stations around the world with thorium ones. The article stated:

Is this too good to be true? A fuel that offers to reduce climate-change gases and consume dangerous weapons-grade plutonium and uranium? Uranium has a new competitor: the dense silvery metal thorium-232. Named after Thor, the Norse god of thunder, the slightly radioactive thorium-232 is three times as plentiful as uranium. Australia has 300,000 tonnes of it in the form of monazite sands, a quarter of world’s known deposits. Thorium-232 is not a nuclear fuel. However, it is very close to being one. Thorium-232, when hit by a neutron, can change into uranium-233, which is a nuclear fuel similar to the uranium-235 used in nuclear reactors now...

When uranium-233 is 'burnt', a neutron strikes a uranium-233 nucleus which splits into lighter nuclei—otherwise known as fission products—and more neutrons. These 'loose' neutrons then go on to strike another uranium-233 nucleus, forming what is known as a 'chain reaction'. As the nucleus breaks apart, it generates heat which may be used to produce high-pressure steam to drive electricity turbines.

However, when the thorium-232-produced uranium-233 is split by a neutron, it does not produce enough extra neutrons to sustain the energy-producing chain reaction. It needs an extra 'injection' of neutrons. This is where weapons-grade nuclear materials come into the picture. Since the nuclear weapons non-proliferation treaty of 1968, the dismantling of nuclear warheads has made redundant hundreds of tonnes of highly enriched weapons-grade uranium-235 and plutonium-239. These explosives must be stored safely to avoid accident and theft. Thorium-232 reactors offer a path to transform these metals into less dangerous materials.

Fuel rods containing mainly thorium-232 can be 'primed' with a smaller amount of either uranium-235 or plutonium-239. This provides the neutrons to transform the more stable thorium-232. These primed thorium-232 rods have another, commercially attractive advantage: they can be used in existing conventional nuclear reactors. Without the weapons-grade plutonium-239 and uranium-235, with thorium-232 reactors will need another source of neutrons. This can be produced by electrically driven linear accelerators. These shoot a 'beam' of neutrons into the thorium-232 to keep it 'burning'. These accelerators can be switched off, stopping the thorium-232 reaction immediately. Because there is three times more thorium than known uranium deposits, it promises a longer-lasting source of non renewable energy. And 'burnt' thorium-232 produces less long-lived radioactive waste than its counterpart.

Time expired.

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