Chernobyl nuclear disaster site given new 'shield'
A new shelter is being built to protect the site of the world's worst nuclear accident, at Chernobyl in Ukraine.
The construction costs over £1bn ($1.46bn/1.38bn euros) and is intended to stop radioactive material leaking, and to allow the old reactor to be dismantled safely.
A catastrophic explosion in April 1986 caused 31 deaths, and the radioactive material released spread across Europe.
The BBC's Science Editor David Shukman went to see the shield being built.
18 Mar 2015