British scientists have used drones to create the most comprehensive radiation maps ever of the fallout zone from the Chernobyl nuclear disaster.
The Red Forest, just 500 metres from the site of the reactor in the Ukraine, is one of the most radioactive places on the planet. The area is considered too dangerous for humans to spend any more than a few hours.
But by using drones fitted with radiation detectors a team from the UK's National Centre for Nuclear Robotics was able to survey the contaminated area in complete safety.
The explosion and subsequent fire in April 1986 caused a plume of radiation that was detected as far away as Western Europe.
In the immediate aftermath workers buried large amounts of contaminated material in the Red Forest. But record keeping was poor and there is no map of the waste dumps.
The British team flew 50 sorties over the forest and surrounding villages with a fixed-wing drone fitted with a laser. It built up a 3D map of the ground, revealing mounds and trenches.
They then returned with a radiation detector mounted to another drone to look for radioactive hotspots.
Professor Tom Scott, of Bristol University, led the research. He told Sky News: "In some of these hotspots you would have received annual permitted dose of radiation in just a few hours.
"For those relatively few areas you don't want to hang around.
"The survey shows where those areas are and helps evaluate whether you should try clean them up or just avoid them."