At a glance: How nuclear waste is stored

11 Nov 2009, 4:31 pm   -   Source: SBS/University of Melbourne
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The Scandinavians, the Nordic countries have a very well developed series of proposals for handling their waste. (Getty Images)

The Scandinavians, the Nordic countries have a very well developed series of proposals for handling their waste. (Getty Images)

Associate Professor Martin Sevior, from the School of Physics here at the University of Melbourne, explains how nuclear waste gets stored.

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Associate Professor Martin Sevior, from the School of Physics here at the University of Melbourne, explains how nuclear waste gets stored.

In an interview from Melbourne University's Upclose podcast, Mr Sevior said the Scandinavians, the Nordic countries have a very well developed series of proposals for handling their waste.

"A nuclear power plant requires around 30 tonnes of fuel per year. At the end of this period of time, at the end of one year it is what's called spent nuclear fuel and is highly radioactive.

"So what happens then is it's placed into cooling ponds and it'|s allowed to cool for five years. In this first period of time a lot of the radioactivity dies away till it's less than 1/10 of what it was when it first was emitted.

"Subsequently, it is placed in either dry storage, then the proposal is to place it into long term geologic storage.

"Now the long time geologic storage developed by the Nordic countries, involves a number of different stages.

"So first stage, is you take the nuclear fuel, and you place it inside a cast iron insert.

"Take the cast iron insert and place it inside a copper canister. You take the copper canister and you place it inside benonite clay.

"And then you take the whole assembly and bury it 500 metres under ground. So the idea is to develop a series of multiple barriers in case something goes wrong with one.

"The next one will succeed in containing the waste. Now each of these barriers are separately designed to be stable for a long period of time.

"For example the copper canister, the innermost or the second most barrier to the waste has been observed to not corrode over a very long time period of time, so for example copper and brass canons from Roman times found at the bottom of the Mediterranean Ocean, have been found to not corrode over a 2,000 year period.

"So you can extrapolate that and say if you put copper in an aqueous environment and remove all of the oxygen, it basically doesn!|t corrode. So what you do then with the benonite clay is arrange that scenario.

"The benonite clay when it absorbs water, ground water, when buried deep underground, swells and expels all of the oxygen.

"So you can actually provide this anaerobic environment, this oxygen for the environment to keep the copper from corroding.

"In addition the benonite clay itself is a substantial barrier should the copper corrode. benonite clays have been observed to contain organic products like pieces of trees for over 500,000 years later, so the piece of tree is still there 500,000 years later.

"Finally you place this thing 500 metres underground in granite rock. The bacteria you find in this granite rock has been observed to retain the fission products, the radioactivity products, that might leap from the benonite clay.

Nuclear waste problem 'still unresolved'

David Noonan, Nuclear free campaigner for the Australian Conservation Foundation is against nuclear power

"All the concerns with nuclear power plants and nuclear waste are all unresolved as they have been in the past", he told SBS.

The issues of waste management, inherent risks of weapons, proliferation and terrorism are all increasing in the world now."

"No country has a disposal site for high level nuclear waste. Countries that claim to be making some progress -- whether that's Sweden or others in northern Europe -- are totally unrepresentative of the nuclear industry.

"They may hold 3-4 per cent of nuclear material, nuclear reactors and nuclear output, but with this public relations claim that nuclear has a role in the future, they are looking to expand nuclear into the developing world, and they will expose those communities to the high level nuclear risks that the west has been unable to resolve," Mr Noonan said.

"It's over 50 years into the nuclear experiment and none has demonstrated the long term isolation of this nuclear waste, no one has been able to deliver a community consensus on whetter that may be done.

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