Drones and robots could form part of a new radiation-monitoring system at the Chernobyl power station in Ukraine, as scientists at the plant fear that existing sensor networks built after the nuclear accident in 1986 have been at least partially destroyed by Russian troops.
When Russia seized the Chernobyl plant in February, the sensors monitoring gamma radiation levels quickly went offline and most remained that way. A spike in levels seen on 24 February, the day troops rolled in, was initially believed to be due to contaminated dust kicked up by tanks, but it is now considered likely that interference from military equipment could be to blame for erroneous readings.
The exclusion zone around Chernobyl was covered by a large network of 67 sensors known as the Comprehensive Radiation Monitoring and Early Warning System. These sensors communicated wirelessly with a base station at the plant. There is also an older network of 28 gamma radiation sensors known as the Automated Radiation Monitoring System. These are physically wired to the central base station.
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at the Institute for Safety Problems of Nuclear Power Plants (ISPNPP) in Ukraine, which oversees research at Chernobyl, says that, at the beginning of this year, there was no need or plan to upgrade these sensors. But since then, much has changed. Although Russian troops have now retreated, scientists haven’t been able to return to their labs because vast areas of the exclusion zone are now littered with landmines.
What scant details have emerged from limited visits by ISPNPP staff to the site show that computer servers and other equipment used to collect and back up radiation data have been destroyed or stolen. Pareniuk says the sensors, which are housed in small, steel buildings, may have appeared to be military equipment to Russian troops and may have also been actively targeted. She says there is hope that some sensors in more isolated parts of the exclusion zone remain, but she is pessimistic about the extent of the damage they may have incurred.
Speaking at the International Conference on Nuclear Decommissioning and Environmental Recovery on 28 April – which was due to be held in Slavutych, Ukraine, but was entirely online because of the ongoing war – Pareniuk said that she and her colleagues believe vital historical data has been lost and their ability to take new readings has been destroyed.
“All servers and software were stolen and we know nothing about the destiny of the monitors that were mounted outside,” she says. “The current monitors are most likely ruined, so we will have to think about the next ones. It’s quite obvious that we’ll need a new monitoring system. And to make something new, you need to learn from all of the experience that we already have globally.”
Japanese scientists were invited to the conference to talk about their experience monitoring safety in the wake of the Fukushima Daiichi nuclear plant meltdown in 2011. at Fukushima University described Japan’s efforts to take soil samples from key areas while also surveying radiation levels across the entire country from the air using helicopters and drones, and collate the two. “Monitoring from the sky is a very effective method to quickly determine a contamination distribution over a large area,” he said.
Pareniuk says that any approach that stops people from having to explore Chernobyl’s exclusion zone by foot could save lives, because of the mines that have been placed there.
Another tactic suggested at the conference was robotic exploration. Although rudimentary robots trialled in the wake of the Chernobyl disaster suffered failures caused by radiation damage, technology has since improved and they would no longer have to be exposed to such enormous radiation levels as seen in the ruins of the reactor itself.
at the University of Bristol, UK, has tested a portable sensor that can monitor radiation levels and even detect individual isotopes from a distance. This device can be mounted on a tripod and was tested before the invasion on a surveying radiation levels at Chernobyl itself. Because radioactive particles can wreak havoc on electronic devices, Verbelen and his colleagues had to design some of their own radiation-resistant components from scratch.
“Radiation-resistant components already exist, usually for aerospace or military applications, but are extremely expensive,” he says. “And there is a very limited supply chain, as well as export restrictions.”
Verbelen says these robotic devices may be able to roam the exclusion zone and safely map radiation levels in fine detail. His team has also worked on using drones to map radiation, with devices that cost as little as £420 and sensors that bring the total cost per machine to about £12,600.
Although there are technical solutions to the problems caused by the Russian invasion, price will be a factor. Even so, Pareniuk and her colleagues will recommend the restoration of the existing network, as well as a nationwide expansion and robotic surveys.
, director of the ISPNPP, has said that money to rebuild and replace equipment won’t be available while Ukraine is at war and will be difficult to secure even in the aftermath. Funds are also needed elsewhere, such as an estimated £42 million to build a new road between the Chernobyl site and Slavutych, where many of the plant’s scientists live, without passing through Belarus, which has assisted Russia’s invasion.
But the funds will need to be found if the Ukrainian and global scientific community is to safely monitor the world’s most contaminated nuclear site. at the University of Salford in the UK said at the conference that it is vital to have accurate data. “Being able to definitively explain what happened and why is important,” he said. “It’s important to ensure confidence in the gamma ray-monitoring network, and that’s important from a public reassurance perspective. It’s also important because this network is a core part of the international safeguards for nuclear sites. Radiophobia is easily resurrected.”
