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Thirty years after the world's worst nuclear disaster, some want to turn it into a wildlife reserve, others - a nuclear waste dump.
Fred Pearce

New Scientist
15 Mar 2016 - 3:03 PM  UPDATED 15 Mar 2016 - 3:03 PM

A white-tailed eagle soars in the clear winter air. It is hunting for fish in one of the most radioactive bodies of open water on the planet: the 12-kilometre-long cooling pond whose waters doused the burning Chernobyl nuclear power station after it exploded 30 years ago.

The pond is radioactive – as are the fish. But they are also abundant. Wildlife is booming in the exclusion zone that stretches for some 30 kilometres from the corroding plant.

Grey wolves, lynx, wild boar, rabbits, moose and the occasional brown bear roam the zone, says Denis Vishnevsky, an ecologist at the EcoCentre, which monitors the Ukrainian half of the exclusion zone.

Yet plans to turn the zone into a nature reserve are under threat from the nuclear industry, which wants to use the area to dispose of high-level radioactive waste. The future of the region may soon be settled as decisions are made ahead of the 30th anniversary of the world’s worst nuclear disaster, on 26 April.

Falling radioactivity

On one hand, things are improving. The region’s radioactivity levels are falling. In fact, 2016 marks the half-life of the two most dangerous isotopes released by the disaster that are still present in the landscape: caesium-137 and strontium-90.

That means just half the amount of these isotopes released remains in the environment, the rest having decayed. Each emits beta and gamma radiation as it decays, which can penetrate human tissue.

Most of the exclusion zone now has radioactivity levels for caesium-137 that are below 500 kilobecquerels per square metre, says Jim Smith of Portsmouth University in the UK, who has run three European Commission studies on the environmental impacts of the Chernobyl accident.

He says this is a safe level of exposure for people, provided they don’t eat mushrooms and berries, which concentrate radioactivity.

Pripyat, the ghost town adjacent to the plant, is still unsafe; but the town of Chernobyl, 10 kilometres away, where many workers in the exclusion zone live part time, could be repopulated safely, he says.

But not everyone agrees. The exclusion zone still contains a large proportion of long-lived isotopes locked up in ecosystems.

This fallout has been contained within the zone’s soils, pine forests and wetlands, which have been left alone to allow the isotopes to slowly decay, says Vishnevsky. But should something happen to release this radioactivity, it could endanger any settled population.

Fire risk

Fires in the forests that now cover more than half the zone are one worry. The risks are increasing as unharvested wood accumulates. Also, the most radioactive forests contain fewer leaf litter-eating microbes and insects, meaning that litter is also piling up, ready to burn.

Last April, an estimated 131 square kilometres of forest burned in the zone. Afterwards, scientists and firefighters demanded a network of smoke monitors across the zone but there has been no money forthcoming.

Then there are the floods that can wash the contamination from local wetlands into the nearby Pripyat river, which provides some of the drinking water for the capital Kiev downstream. Big dykes have been dug to prevent the flood waters reaching the river.

Another emerging risk is the spread of radioactive sediment by wind: as the cooling pond next to the power station is drained, the sludge at the bottom – until now protected by a layer of water – will be exposed (See “Hung out to dry” below).

Sergey Kireev, director of the EcoCentre and a proponent of the nuclear waste depository idea, raises another concern. The plutonium isotopes have half-lives of thousands of years. And americium-241, a decay product of plutonium, has one of 432 years. Both emit alpha radiation, which can be stopped by the skin, but cause damage if ingested.

Smith says the risks from these isotopes are low, but Kireev thinks their continued presence means it would be unsafe for people to return to the area for thousands of years.

Despite such concerns, however, some people are already back.

Returning evacuees

Around 6000 work in the exclusion zone up to four days a week. Some are erecting a new confinement that will be installed on top of the existing leaky and rusting “sarcophagus” that houses the wrecked Chernobyl nuclear reactor sometime next year. Others, like Kireev, are support staff managing the zone.

Also scattered across the exclusion zone are a hundred or so ageing returnees, who snuck back to their houses because they didn’t like life as evacuees. They have no truck with radiation fears.

Hale and hearty 78-year-old Eugene Fedorovych tells me he and his wife told security staff who tried to stop them illegally catching radioactive fish in Pripyat river to “go away”.

Even tourists are allowed to visit Pripyat, the former model Soviet town that now has 20-metre trees bursting through the concrete in the town square.

But officially the zone is still not being repopulated. So why not turn it into a wildlife reserve?

Wild animals are returning anyway. To the north, Belarus has turned its section of the exclusion zone into the Polesye State Radioecological Reserve.

The idea of doing the same in Ukraine was floated in 2014 by officials at the environment ministry. Ecologists on Kireev’s staff would love to create one, and the World Bank’s Global Environment Facility has proposed a cross-border reserve that would cover 5000 square kilometres.

In February, media reports suggested the plan could become official policy in time for the 30th anniversary of the disaster.

But Kireev dismisses the idea. Wildlife is no more welcome than people in the vision for the zone’s future he subscribes to. The reason, ultimately, has more to do with politics than radiology.

More than half of Ukraine’s electricity is produced by nuclear power plants. The spent fuel this leaves behind now badly needs a home following a recent decision to stop sending it to Russia for treatment.

Storage solution?

The government is already building an interim store for spent fuel in the exclusion zone, close to the abandoned village of Buryakivka. The next step is building a permanent geological repository.

“Because the zone is unpopulated, it makes it very attractive,” Kireev says, and shows me a map of potential sites.

It would also be cheap. Without people to relocate and compensate, it could be built for $2 billion, he says, against as much as $70 billion outside the zone.

For him, the future of waste depositories takes precedence over creating wildlife reserves. And he’s not the only one.

There appears to be a battle going on inside the Kiev government over the future of this poisoned landscape. And local experts think a decision may be only days away.

Whatever emerges, it’s likely to determine the fortunes of locals, wildlife and the nuclear sector for the next 30 years.

Hung out to dry

In the days after the Chernobyl disaster, Gennady Laptev, then a young government hydrologist, was rushed to the scene to help prevent radioactivity pouring down the Pripyat river into the drinking water of the Ukrainian capital Kiev. Today, as head of the radiometric laboratory of the Ukrainian Hydrometeorology Institute, such concerns are on his mind once again.

He took me to see the cooling pond built for the Chernobyl power station, which in 1986 received huge amounts of radioactive material from atmospheric fallout and deliberate dumping as workers sought to douse the inferno. Most of the contamination ended up in the pond's sediment, shielded from the wider environment by the water above. But that is set to end.

In 2014, to save money, the government stopped pumping water from the Pripyat river into the pond, which sits some 7 metres above the river's level. "Within four years, 90 per cent of the pond will be gone," says Laptev. The sediment, containing more than 300 terabecquerels of radioactivity, will be exposed to the air.

This doesn't have to mean radioactive dust storms. His modelling studies found, for example, that if the pond is replaced by marshes, they could retain up to 80 per cent of the radioactivity. But no one is planning to plant any marshes yet.

For now, what's needed, he says, is for radioactive hotspots on the exposed pond bed to be pinpointed; the changing water chemistry of the contracting pond to be monitored to ensure no isotopes are released into water draining into the Pripyat river; and radioactive dust in the wind to be measured.

But so far there has been no funding for this. And neither the EcoCentre nor the power-plant operators want to take responsibility for the safety of the pond as it empties.

"I appeal to the scientific community to come and study what is happening here," he says. "The pond is unique, but time is passing and the pond is disappearing forever."

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This article was originally published in New Scientist© All Rights reserved. Distributed by Tribune Content Agency.