PARIS, March 15, 2011 (AFP) - The concrete vessel around the No. 2 reactor at Japan's Fukushima plant, designed to contain radioactive debris, is "no longer sealed," Andre-Claude Lacoste, head of France's Nuclear Safety Authority (ASN), said on Tuesday.
Lacoste was speaking at a press conference in which he also said the accident at Fukushima now rated six on a seven-point international scale of gravity, placing it second to Chernobyl as the world's worst nuclear disaster.
The ASN is being briefed by the Japanese authorities and by a specialist from France's Institute for Radiological Protection and Nuclear Safety (IRSN), according to the agency.
The confinement vessel, made out of reinforced concrete, surrounds the steel vessel that houses the nuclear reactor.
It is designed to contain radioactive gas or dust, preventing them from being expelled into the air.
In a press statement, the ASN said two "successive explosions, at 6:10 am and 10:00 am local time probably caused damage to the confinement vessel which is the source of the significant increase in detected radioactive releases."