Scholarship entry: The first time I saw...

The scale is all wrong. It's like discovering that Mt Vesuvius is a molehill, or that the aircraft which destroyed the Twin Towers were paper planes carelessly tossed from an office window. As the tour bus passes the long, low Chernobyl power station, our guide points out the sections which house the four nuclear reactors. Reactors 1 and 2 are identifiable by their thin white chimneys. These remind me of the chalky candy-sticks I used to eat as a kid. With its immense lighthouse-like chimney, Reactor 3 is equally easy to spot. But when the guide announces that we can now see the sarcophagus that entombs Chernobyl's fourth reactor, there's that awkward moment in a tour group where each person is hoping someone will ask the question that no-one else dares to: “where?”

We've been wandering around the abandoned city of Pripyat, two kilometers away from the nuclear power station. On April 26th 1986, after Reactor 4 exploded, the 50,000 strong population was evacuated. The city still lies empty today. Nature has moved in: plants climb up walls and explore balconies. Trees shuffle onto the city square. We are ghosts in childless, ruined schools; shoppers amongst husks of rusting freezers in deserted supermarket aisles.

The scale is all wrong. It's under there – 250 tons of radioactive material buried beneath the squat sarcophagus tacked on to the end of the power station like an afterthought. We stand just 500 yards away now, with a monument to the disaster in the foreground. Nature has moved in here too; these trees look exactly like Norwegian Pines. It's 25°C and there are Christmas trees in Chernobyl. It's impossible to believe that Pandora's Box is still emptying itself under this collection of stained blocks.

The Soviets built the sarcophagus to contain the radiation still leaking from the reactor. Sarcophagus – from the Greek “flesh eating,” as if it were a giant concrete and steel Pac man, devouring toxic ghosts. The Russian name translates differently, as “sheltering” or “covering.” Do you want reassurance or honesty? 26 years later, it's hard to feel reassured. The sarcophagus is covered in a lattice work of scaffolding as rusted as an old climbing frame.

The River Pripyat flowing past the power station is as blue as the sky. Our Geiger counter squeals as it registers radiation levels 65 times that of London. It's like the mildly irritating buzz of an insect that can be lazily wafted away.