It is almost 30 years since the Chernobyl disaster, a catastrophic nuclear accident at the Chernobyl nuclear power plant in Ukraine, then part of the USSR. On 26 April 1986 technicians at reactor number four of the nuclear power plant were conducting a systems test when there was a sudden power surge. The reactor's fuel elements broke, leading to a huge explosion and blowing off the reactor cap. This exposed the graphite covering the reactor to the air, and it ignited. The fire burned for nine days, sending a huge plume of radiation into the environment. It has been estimated that the Chernobyl disaster released into the atmosphere 400 times more radioactive material than the atomic bombing of Hiroshima in 1945.

The disaster killed 31 people almost immediately – almost all of them reactor staff and emergency workers. Between 30 and 50 emergency workers died shortly afterwards from acute radiation. The long-term effects are not yet known but a report suggested the eventual death toll could reach 4,000.

The town of Pripyat, just a few kilometres from Chernobyl, was built in the 1970s to house the plant's workers and their families. Around 50,000 people once lived here in apartment blocks on tree-lined streets. The town had 15 primary schools, five secondary schools and a technical college. There was a hospital, two sports stadiums and an amusement park. Today Pripyat is a ghost town, its streets overgrown, its apartment blocks lying derelict. Books and toys litter the schools and kindergarten, a reminder of how quickly they were evacuated. The rusting Ferris wheel that still dominates the town has been widely photographed, and has become a symbol of the world's worst nuclear disaster.

The village of Kopachi, only a few kilometres south of the plant, had a population of 1,114. The village was so badly contaminated by radiation fallout that authorities bulldozed and buried all of Kopachi's homes and buildings, apart from the kindergarten. Today Kopachi, which lies in the inner exclusion zone around Chernobyl, is still contaminated with plutonium, cesium-137 and strontium-90.

The former Chernobyl power plant is currently undergoing a decades-long decommissioning process of reactors one, two and three, which continued in operation for years following the accident at reactor four. A consortium of Western companies is building a movable enclosure called the New Safe Confinement that will cover the reactor remains and its fragile sarcophagus in order to prevent further contamination.

The Chernobyl Exclusion Zone was established soon after the disaster. All villages in a 30km (19 mile) radius of the plant were evacuated and placed under military control. The Exclusion Zone has since been widened and it now covers an area of 2,600 square kilometres (1,600 square miles). Today the Exclusion Zone is one of the most radioactively contaminated areas in the world, but radiation levels vary widely across the zone.

Nobody can say for sure when the area will be safe again, but some scientists estimate that it could be 20,000 years before people can live near the plant again. On an encouraging note, wildlife is thriving inside the Chernobyl Exclusion Zone, with elk, roe deer, red deer, wild boar, and wolves flourishing at the site of the world's worst nuclear disaster.