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World leaders jostle with global executives and anonymous men dressed in full camouflage as platters of shrimp, foie gras and cheesecake are passed around by white-gloved staff. It would all seem quite normal were it not for the fact that we’re just 100m (330ft) away from the site of the worst nuclear disaster in history.

A hospitality tent has been erected just inside the gates of the Chernobyl nuclear power plant near Pripyat in Ukraine. The tent has many windows, to ensure everyone gets a good view of what’s about to happen.

These guests are here to witness the final stage of a 30-year clean-up job that has been underway, on and off, since one of the plant’s reactors exploded in 1986. The Chernobyl disaster still casts a pall over nuclear power. And other serious accidents, such as that at Fukushima in Japan in 2011 – the only other incident to be classified a maximum Level 7 in the seven-point International Nuclear Event Scale – are weighed against it.

It also set in train a series of measures to ensure nuclear safety around the world. Now the whole site is about to be encased inside a vast structure known as the sarcophagus, sealing in some of the most dangerous waste material in the world for at least 100 years.