Imagine a ghost town with no inhabitants, houses and flats left abandoned with scattered possessions and the streets empty of traffic.
This unsettling scene is a reality in desolate Pripyat, once home to 50,000 residents in Ukraine - but built to serve the Chernobyl nuclear plant less than two miles away, the site of one of the world’s worst nuclear tragedies.
Around 600,000 people are thought to have been highly exposed to radiation when one of the plant’s reactors went into meltdown on April 26, 1986, sending lethal particles into the air. More than 50 people died as a direct result of the disaster, and it is estimated that there may be 4,000 extra cancer deaths linked to the catastrophe.
The problems caused by Chernobyl are unlikely to be fully solved for thousands of years - so Professor Neil Hyatt, from Sheffield University, is aware that his work leading the decommissioning of the site will help to reduce the hazardous legacy handed to future generations.
Prof Hyatt’s team of around 50 researchers are also focusing on the clean-up of nuclear waste at locations such as Sellafield in Cumbria and Fukushima in Japan, where a plant was damaged by a tsunami in 2011.
The expert, a specialist in nuclear materials chemistry, has visited Pripyat and Chernobyl with colleagues and students twice, in July and October last year, and found the experience deeply affecting.
“There’s no doubt that this is one of the most radioactively hazardous locations on the planet,” he says in his office at the Sir Robert Hadfield Building off Mappin Street.
“I felt a little uncomfortable in some ways, because I was conscious about not playing the tourist. It’s very difficult when you’re a scientist because your work is very personal to you. You want to see, but you also want to respect the consequences of what’s happened.”
He says the area - subject to a 20-mile exclusion zone - was ‘exceptionally eerie’.
“It’s silent, with no people, and the buildings are in a state of disrepair and overgrown. There are a lot of normal family pets, dogs and cats, that have continued to breed and are sort of feral. But Chernobyl itself was very active, with lots of people, and heavy engineering equipment moving around. In some ways there was an air of normality to it.”
In November last year a new £600 million steel arch covering reactor 4, the broken unit, was slid into place, sealing the old concrete ‘sarcophagus’ which had started to crumble. Next year the first phase of decommissioning will start.
Prof Hyatt explains that, during the accident - caused by a mixture of flawed Soviet design and human error - the fuel inside the reactor melted and turned into a lava that dripped through the basement of the building.
The highly radioactive material, which would deliver a lethal dose within minutes, is ‘still there’, he adds. Meanwhile the old reactor lid, which weighs several hundred tons and was blown off during the explosion, is balanced on top of the reactor ‘at an angle of near vertical’.
“If that moves it’s going to raise a load of radioactive dust,” says the professor.
“One of the worries when you’re taking this apart is you don’t know how the load is distributed.”
The Sheffield researchers are working to advise those handling the clear-up on better measures to take, chiefly by understanding chemical reactions that are causing the lava to corrode.
“The end point of the decommissioning will be to use robots to go in and start retrieving the lava material. It will then have to go into an underground disposal facility. That same science we’re doing will allow us to predict how long it will last underground.”
The new arch will last for 100 years, and it will take at least 30 years to ‘retrieve the core material’, he says.
“Very similar techniques will be required at Fukushima.”
Last week the professor hosted a team from Ukraine’s Institute for Safety Problems at Nuclear Power Plants, which is based in an old school building within the exclusion zone.
The visit was part of a scheme called the Global Challenge Research Fund, aimed at forging links between research groups.
“The reason our project was accepted is because seven per cent of Ukraine’s GDP is spent on Chernobyl-related issues every year,” says Prof Hyatt.
“Until they get that sorted, it’s going to be very challenging for them to develop as an economy.”
A joint project with Japan is also being run by the department, looking at treating the waste water on site. Prof Hyatt went there last April and is set to go again this year, but he laughs off any suggestion that he’s had his ‘dose for life’ of radiation.
“Nuclear energy is particularly challenging in its public engagement, and much of that is because radiation is a hazard that can’t be smelled, seen or sensed. It’s invisible. Understanding the impacts of that in a very catastrophic way really gives you an authority when you’re talking with the public, because you’ve seen that at its very worst.”
The professor is part of the largest team of its kind in the UK. They work with ‘small quantities’ of radioactive substances in the secure laboratories, coming up with new ways of storing waste - from spent fuel to boiler suits, metal and masonry - such as sealing it in glass.
Prof Hyatt grew up in Harrow in London, studied chemistry to degree and PhD level at Birmingham University, then moved to South Yorkshire 15 years ago to work at London & Scandinavian Metallurgical Co in Rotherham.
He joined the university when the radioactive waste group was first set up, and is now head of the Department of Materials Science and Engineering. The 43-year-old, who lives in north-west Sheffield with his wife, says: “I’d always been fascinated by radioactivity as a kid. It’s kind of the only way you can turn one element into another - that’s just really interesting.”
His job is ‘very rewarding’, he adds - but emphasises the ‘strong need’ to recruit new researchers.
“It’s been a fantastic opportunity for me.”
Nuclear method ‘still worthwhile’
Professor Neil Hyatt believes building nuclear power stations is ‘still worthwhile’, despite the huge cost and associated risks.
“It’s clear that we do need to de-carbonise our economy and nuclear power is a source of low-carbon electricity. There’s still uncertainty to the extent to which it’s affordable, but it is capable of providing a very substantial contribution to our energy supply.
“If you take one molecule of methane, and you burn it, on the energy scale you get four electron volts, and if you take a uranium atom and you burn it, you split it into two pieces, and the energy you release is 200 million electron volts. So it’s far greater.
“That factor means it’s still worthwhile, even with all the costs you need to run a nuclear power station safely, and dealing with the radioactive waste.”
He said the UK will need to replace nuclear power like-for-like in the near future, but the university was carrying out plenty of research on renewable sources such as solar and offshore energy.