"Even if the radiation levels did not change, this is a worrying sign," Vladimir Churov of Greenpeace in neighbouring Russia told the Interfax news agency.
"If there are sections in the turbine hall that are falling down there is no guarantee that the sarcophagus built in 1986 will not be the next to fall."

The 80 Vinci and Bouygues workers employed to set up the new shelter over the exploded reactor as part of the Novarka consortium were all given radiation checks and evacuated, a Bouygues spokesperson said.
"Novarka is employing all measures to limit surface contamination. These are currently within admissable limits."

However the spokeswoman for the Chernobyl plant, Maya Rudenko, dismissed Greenpeace's concerns and said that the existing sarcophagus had been strengthened from 2004-2008 and could last until 2023.

"There is absolutely no risk," she said.

The area of the accident is estimated at about 600 square metres, the emergency agency said.
A statement on the website of the power station described the accident as the "partial failure of the wall slabs and light roof of the Unit 4 Turbine Hall."
[link to www.nzherald.co.nz]