Fukushima crisis could last months – French safety agency

Three reactors at Japan’s Fukushima nuclear plant remain “precarious,” a state that could last for “weeks or even months,” France’s Institute for Radiological Protection and Nuclear Safety (IRSN) said in a statement yesterday.

It said it remained “greatly concerned” by the situation in the No. 1, 2 and 3 reactor units, which have been hit by a series of blasts and fires since the plant was hit by the March 11 earthquake and tsunami.

The IRSN said it was running through scenarios for potential impacts for the environment in the hypothesis that there had been a breach of the pressure vessel – a steel container that encloses the reactor core – in the No. 3 unit.

On Thursday the agency noted there had been black smoke rising from the No. 3 unit this week.

Among the theories to explain the cause of the smoke is a chemical reaction between a molten radioactive slag called corium and the concrete of the containment vessel that provides a protective shell for the pressure vessel, it said.

If the corium burns through the containment vessel’s concrete floor or other protections, that boosts the risk that radioactivity can enter the environment through the soil.

A spokesman for the plant’s operator, Tokyo Electric Power Co. (Tepco), said yesterday “it is possible” that the pressure vessel in the No. 3 unit had been damaged. There were no further details.

“Radioactive substances have leaked to places far from the (No. 3) reactor,” a spokesman for the nuclear safety agency, Hideyuki Nishiyama, said.

“As far as the data show, we believe there is a certain level of containment ability but it’s highly possible that the reactor is damaged.”

Two workers at the plant were hospitalised on Thursday with radiation burns after stepping in highly radioactive water in the basement of the No. 3 unit’s turbine building.