On Wednesday, the nuclear threat raged on in Japan and at the European Commission there were even talks of an "apocalypse."

The UN nuclear watchdog chief on Wednesday described developments at the Fukushima nuclear power plant as "very serious", as he prepared to head to the country to assess the situation.

Yukiya Amano said he hoped to fly to Japan on Thursday for a one-day trip and needed more information from authorities there.

"The situation... is very serious," Amano, a Japanese national, told a news conference, saying damage to the core of three units at the Fukushima Daiichi nuclear reactor had been confirmed.

The crisis reached level six of seven on the International Nuclear Event Scale, and it is believed possible that sooner or later it will reach seven, the same as that of the 1986 disaster in Chernobyl.

On Tuesday night there was a further fire at reactor number four of the Fukushima plant and radiation continues to be out of control. It is believed that radiation emissions may come from reactors 2 and 3 of the plant.

Military helicopters sent to dump water on reactor number three were unable to fulfill their mission due to the intensity of the radiation, Kyodo news agency reported quoting Japanese Defense Ministry officials. The helicopters, belonging to the national army, are now waiting to retry the operation, thereby facilitating the cooling of the reactor core.