Tuesday, October 19 2021

Two weeks ago, Australia and the United States announced an agreement to fund a fleet of new nuclear-powered attack submarines to patrol the Indo-Pacific, all part of the new AUKUS defense pact that wreaked diplomatic havoc in Europe and beyond.

The announcement reignited the centuries-old debate between pro and anti-nuclear lobbies in Australia.

On a reading, it is a trial without an object.

It is currently illegal to build or operate a nuclear reactor: the only nuclear reactor in Australia is ANSTO’s OPAL reactor, which is used only for research purposes, to create nuclear medicine.

The debate is loaded in Australia for a series of complex reasons, including that while some see it as a solution to the climate crisis, others see it as a recipe for environmental disaster, or simply a costly distraction from more renewable energy methods. effective. .

Many of the concerns that surround nuclear power – and nuclear submarines in particular – relate to the supply chain. Where will the enriched uranium needed to fuel submarines come from? And what are we going to do with nuclear waste?

Uranium mining and enrichment for nuclear energy

According to Andrew Stuchbery, professor of nuclear physics at the Australian National University (ANU), most of the uranium mined from the ground is not “fissile”, which means it cannot undergo nuclear fission.

“When you mine uranium, it contains two isotopes, uranium 235 (U235), which is only 0.7% of the composition, and the remaining 99.3% is uranium 238 (U238), but it’s U235 that undergoes neutron-induced fission, ”says Stuchbery.

“For typical power reactors, you enrich the U235 content to about 5%, which is the definition of low enriched uranium, and the highly enriched uranium is around 20%.”

Enrichment, in layman’s terms, involves filtering some of the U238 to make the “mixture” slightly more abundant in U235, making it a suitable fuel for nuclear power. As Stuchbery explains, uranium must be in gaseous form so that the U235 and U238 atoms can be separated from each other. To do this, the uranium is transformed into uranium hexafluoride.

Then the gas is introduced into a centrifuge, where it is separated into two streams – one enriched in U235 and the other made up of “tails” with a lower concentration of U235, known as “depleted uranium”. “.

Although the uranium is mined in Australia, we currently do not have the centrifuge technology required to enrich it.

As Professor Ian Lowe, an energy expert at Griffith University, explains: “If Australia decided to use nuclear power, we should think about how we would provide uranium enrichment services and fuel fabrication.

“If we didn’t enrich our uranium ore, we would have to negotiate with somewhere overseas to ship the yellowcake [a type of uranium concentrate powder created in the processing of uranium ores], do the enrichment, have the fuel made, then bring the fuel rods back to Australia.

“So rather complicated international negotiations should be conducted within the framework of the non-proliferation treaty, which sets limits on the level of enrichment available.”

Storage and disposal of nuclear waste

Nuclear reactors produce dangerously radioactive waste, although it is not produced in massive quantities: it has been said that the 88,000 tonnes (roughly 80,000 tonnes) of waste ever produced by reactors in the United States could hold up. on a single stacked football field 24 feet high.

But a major problem is how to store this spent fuel in a place where it cannot infiltrate ecosystems and cause irreversible damage until its half-life is exhausted – which can range from a few seconds to thousands of years.

Stuchbery says waste products with the shortest half-life are the most radioactive but the easiest to process because their radiation levels drop quite quickly. With this type of waste, keeping it cool is essential – Stuchbery says that failure to keep this type of waste cool caused the Fukushima disaster in 2011.

Once it’s cooled down enough, Stuchbery says there are different options.

“The French are reprocessing their nuclear fuel, which has two advantages,” he said. “One is that the uranium 235 content in used fuel is actually higher than the U235 content in the uranium you extract from the ground. And you also have plutonium in the spent fuel that can be chemically extracted and used as fuel. “

But Stuchbery says this introduces problems, because this reprocessing involves the same chemical processes associated with extracting military-grade plutonium from radiated uranium in a reactor, so countries like the United States have a policy avoid reprocessing and go directly to storage.

Additionally, Stuchbery says the incentive for reprocessing is not high because uranium is so abundant in the earth’s crust.

The other option, then, is to simply store the spent fuel for as long as it remains radioactive, which can take minutes or millennia.

“In most commercial power plants, a lot of the fuel is still just stored on-site at the plant, because we haven’t been that far in the United States or Australia to actually have a designated storage facility for. nuclear waste, ”explains Stuchbery. . “It’s a good technology to do, but getting the public license is the obstacle. “

Stuchbery says other countries, such as the Scandinavian countries, are well advanced in storing their nuclear waste, where it is buried deep in the ground, protected by miles of rock. But getting a public mandate to build such a facility in Australia, a notoriously anti-nuclear country, would be difficult.

“People are working on this technology all the time, but because it’s nuclear technology, it requires a social license,” he says. “So what happens at the end of the day is not just going to be engineering. “

Lowe agrees.

“In Australia, we spent 20 years trying to get an agreement for a national low-level waste disposal site,” he says. “And we’re still grappling with the question of finding a community, so I’m not at all optimistic that we would easily find a way to deal with radioactive waste if we had nuclear power plants.”

How do other countries handle this?

In this week Weekly Cosmos, Jamie Seidel examines the arguments for and against nuclear in Australia, as articulated by two Australian experts.

We decided to speak to an international expert from a country where there is already a nuclear industry to get an idea of ​​why other countries are using nuclear energy.

Professor Martin Freer is a nuclear physicist at the University of Birmingham, UK, who has helped inform UK energy policy. Freer says most of the UK’s nuclear reactors were built in the 1970s, so the idea of ​​nuclear power has had time to crystallize in public consciousness and be accepted – at least by some. .

“For the moment, there is no major anxiety [in the UK] around nuclear energy as a technology; I think the main angst is the economy of it, ”Freer said. “The main discussion going on in the UK is, is nuclear just too expensive compared to other means of generating electricity? “

But Freer says many energy costs don’t factor in important limiting factors.

“It’s not just the cost of a wind power plant or a wind farm, you have to think about the fact that wind and solar are intermittent, you have to cost the power generation you need when the wind is not blowing or the sun is not shining, ”he said. “The way we deal with this variability right now in the UK is through gas supply, so we have gas plants that can be turned on and off.”

Freer says these gas power plants are then left idle, so the cost of electricity is higher. He sees nuclear power, by contrast, as a solution to the looming threat of climate change and the imperative to wean off fossil fuels.

“Using gas as a backup solution is an expensive solution. So anyone who builds an energy system has to think not only that we have to reach net zero, but how do you manage this energy system to be reliable? And that means not only energy storage, but also reliable baseload production.

“In the UK context, you would need something like a 40% energy base load, and nuclear could do that.”

But the UK still has its own supply chain issues. According to Freer, the country used to reprocess its fuel, but this was phased out when it was no longer seen as economically viable. The UK is now storing its nuclear waste in containers at temporary storage facilities.

“The UK is in the process of finding a site for a geological storage facility,” Freer said. “So that would be deep underground, you put the waste containers securely in the facility, and you don’t have to worry about it anymore as long as you understand the geology well enough and therefore know how this is stable. the radioactive fuel will extend over a period of tens of thousands of years.

According to Freer, communities have been invited to bid for the chance to host this installation in their backyard – a process virtually unimaginable in Australia.

“It might sound a little surprising, but of course there will be benefits, there will be investments in these communities and there will be jobs that go hand in hand,” he says. “So for rural communities, it’s a way to reinvigorate these communities. “

So, does Freer think Australia will ever switch to nuclear power?

“The irony, of course, is that Australia has a lot of uranium, so it’s an integral part of the nuclear fuel cycle, so you benefit from the nuclear power industry economically. But there is an extraordinarily strong political lobby around coal.

“For me, the big challenge Australia faces is: how do you break the grip of the coal industry on politics?


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