Last Update: Friday, April 14, 2006. 11:11am (AEST)
Scientist urges switch to thorium
Supporters of an alternative energy source say it has the potential to revolutionise the nuclear power industry and is a safer alternative to uranium.
Thorium oxide, which is three times more abundant than uranium, is also a radioactive material.
But senior research scientist Dr Hashemi-Nezhad, from Sydney University, says it is safe to hold in your hand.
"This is the future of the energy in the world - energy without green, without greenhouse gas production," he said.
Dr Hashemi-Nezhad says thorium has all of the benefits of uranium as a nuclear fuel but none of the drawbacks.
It can generate power without emitting greenhouse gases and it can be used to incinerate the world's stockpiles of plutonium.
Dr Hashemi-Nezhad says thorium waste would only remain radioactive for 500 years, not the tens of thousands that uranium by-products remain active.
"In fact, the green movement must come behind this project because we are moving in a direction to destroy all these existing nuclear wastes, to prevent nuclear weapons production, to [prevent] Chernobyl accident happening again," Dr Hashemi-Nezhad said.
Unlike uranium, thorium is not fissile, meaning it must be coaxed into a chain reaction.
At present, there are two methods of achieving this: a mixed fuel thorium reactor, which uses a small amount of uranium to kick-start the nuclear reaction; and then there is the project that Dr Hashemi-Nezhad is working on.
"A particle accelerator is coupled with a nuclear reactor," he said.
"A beam of protons sent from the accelerator heats a heavy metallic target, such as lead, and produces huge number of neutrons.
"These neutrons start the chain reaction in the reactor. And once you switch off the accelerator, everything dies down."
The thorium reactor being proposed by Dr Hashemi-Nezhad can be switched off immediately in the event of an accident - an option not available in conventional reactors.
But Australian Conservation Foundation president Ian Low says although thorium has advantages he says using thorium is like being run over by a diesel train rather than a steam train.
"It's true that the period of danger of radioactive waste from thorium reactors, if the design can be worked up and proven, would be hundreds of years rather than hundreds of thousands of years," he said.
"But we're still talking about very long lifetimes."
Mr Lowe says nuclear power is still a long way from becoming clean and green, even with thorium.
"If we spent as much as we spend every year on nuclear research on renewable energy, we wouldn't be talking about this issue," he said.
"We'd have had enough solar and wind and other forms of renewable energy to give us clean energy solutions for the entire future."