Washington and other foreign capitals expressed growing alarm about radiation leaking from the earthquake-shattered plant, 240 km north of Tokyo.
“The situation continues to be very serious,” International Atomic Energy Agency chief Yukiya Amano told reporters at Vienna airport as he left with a group of nuclear experts for Japan.
Workers were trying to connect a 1-km-long power cable from the main grid to restart water pumps to cool reactor No. 2, which does not house spent fuel rods considered the biggest risk of spewing radioactivity into the atmosphere.
One official from the plant operator told a late night briefing the cable could be connected within hours. Other officials said it was unclear if water pumps at reactor No. 2, which sustained less damage from a series of explosions, would work.
The top US nuclear regulator said the cooling pool for spent fuel rods at reactor No.4 may have run dry and another was leaking.
Japan’s nuclear agency said it could not confirm if water was covering the fuel rods. The plant operator said it believed the reactor spent-fuel pool still had water as of Wednesday, and made clear its priority was the spent-fuel pool at the No.3 reactor.
At its worst, radiation in Tokyo has reached 0.809 microsieverts per hour this week, 10 times below what a person would receive if exposed to a dental x-ray. On Thursday, radiation levels were barely above average.
Many Tokyo residents stayed indoors, usually busy streets were nearly deserted and many shops were closed.
Meanwhile, airlines pulled in extra, larger aircraft to help thousands of people leave Tokyo and European carriers began screening aircraft and crew for radiation as Japan rushed to prevent a nuclear disaster.
As an increasing number of governments from Britain to New Zealand to South Korea advised citizens to leave quake-affected northern Japan, airlines mobilized for mainly outbound traffic from one of the world’s biggest cities.
The US State Department said the government had chartered aircraft to help Americans leave Japan and had authorized the voluntary departure of family members of diplomatic staff in Tokyo, Nagoya and Yokohama — about 600 people.
“The situation has deteriorated in the days since the tsunami and... the situation has grown at times worse with potential greater damage and fallout from the reactor,” White House spokesman Jay Carney told reporters.
The US travel advisory came after Australia urged citizens with non-essential roles in Japan to consider leaving Tokyo and the eight prefectures most damaged by the earthquake due to infrastructure problems rather than nuclear concerns.
“We have a real problem in terms of the infrastructure in Japan. We have uncertainty of power supply, we have problems with train services, we have problems with public transport services, many schools have closed and there is this repeated series of aftershocks,” Foreign Minister Kevin Rudd said.
Britain said it was chartering flights from Tokyo to Hong Kong, which would cost 600 pounds ($967) per person. Britons directly affected by the tsunami will be offered the flight for free.
France and Germany have also advised citizens in Japan to get out or head to southern Japan. The French Embassy in Tokyo said it had asked Air France to prepare planes for the evacuation of French nationals.
Air India increased flights and used bigger planes to help bring back Indians from Japan. It has been using a Boeing 747-400 jumbo jet with a capacity of 423 passengers, instead of a smaller Boeing 777-300ER, a spokesman said.
Health authorities in several countries responded to concerns about the possible health impact from radiation starting checks on people, planes and boats.
There were no immediate reports of contamination, although officials in South Korea and Taiwan said some passengers arriving from Japan had been observed with slightly higher levels of radiation.
