Emergency crews at Japan’s earthquake-hit nuclear plant in Fukushima prevented the radiological crisis from spinning further out of control on Friday even as the country’s nuclear watchdog upgraded the accident to a level 5 incident – equivalent to that of the 1979 Three Mile Island incident in the US.
The authorities have been battling the deteriorating situation at all six reactors housed in the nuclear plant, 240km north of Tokyo, since last Friday’s devastating earthquake and tsunami. The concern over the last 48 hours has switched, however, from the reactors themselves to the need to refill water storage tanks containing overheating radioactive uranium.
Japan had initially ranked the accident 4 – defined as involving a minor release of radioactive material with limited local consequences – on the International Nuclear and Radiological Event Scale. But Japan’s Nuclear Industry Safety Agency raised the accident level to 5 – one having wider consequences – on Friday citing that the damage done to the Fukushima plant in the last six days made it necessary.
Meanwhile, Yukiya Amano, director general of the International Atomic Energy Agency, met with Japanese prime minister Naoto Kan and other leaders and said the international community wanted “more and more accurate information, more quickly,” from Japan.
Given the crucial need to cool temperatures in the spent fuel pool and other parts of the reactors, “I think it is a battle against time,” Mr Amano said.
Earlier on Friday radiation readings in one area roughly 30km from the power station – beyond a 20km evacuation zone that has been in place since Saturday – were 100 microsieverts an hour on Friday morning, more than 200 times normal background levels.
However, most areas around the site were showing doses below 10 microsieverts an hour, Yukio Edano, the top government spokesman, said.
Mr Edano said steam rising from the No 3 reactor building – the most critically damaged of the six at the Daiichi facility – indicated that military firefighters had succeeded in at least partially refilling the storage tank on Thursday.
“The No 3 reactor is still the top priority,” said Mr Edano.
The earthquake and tsunami officially became Japan’s most deadly catastrophe since the second world war after the number of confirmed dead rose to 6,539 on Friday, more than were killed in the Kobe earthquake in 1995. More than 10,000 are still officially listed as missing. Meanwhile, governments around the world stepped up efforts to evacuate foreign nationals from Japan.
Emergency workers at Fukushima resumed a new round of spraying on Friday afternoon, using military firetrucks equipped with special shielding to fight aircraft fires but halted the operation after 40 minutes. Air Corps Commander Shigeru Iwasaki said water appeared to have reached the tank but it was unclear whether there would be another round of spraying on Friday.
Meanwhile, electrical engineers were working to connect external power lines and restore power to the station, beginning with the less dangerously radioactive No 1 reactor.
Thirty extra fire crews from the Tokyo Fire Department arrived at the power plant on Friday.
“In the morning the focus is on restoring the electricity systems, and in the afternoon the spraying will start again,” said Toshimi Kitazawa, the defence minister.
Cooling systems that cycle water through spent-fuel tanks at all six reactors failed when backup generators were washed away by the powerful tsunami that followed last Friday’s 9.0 magnitude quake. The failure caused the still highly active uranium to heat up, in some cases boiling away its protective sheath and exposing it to the air.
The roofs of both the No 1 and No 3 reactor buildings were torn away in hydrogen explosions – on Saturday and Monday, respectively – possibly worsening damage to the tanks, which are located on the buildings’ upper floors.
Radiation readings at the western gate of the plant fell slightly after Thursday’s spraying, from 309 millisieverts an hour (309,000 microsieverts) at 3.30pm local time on Thursday to 271 millisieverts an hour at 7.30am Friday, nuclear safety authorities said.
Readings in Tokyo on Friday morning remained close to normal background levels, at 0.0483 microsieverts, according to the Tokyo metropolitan government.
The International Atomic Energy Agency said on Thursday that the overall situation was “very serious” but did not appear to be deteriorating. The chief US nuclear regulatory official said radiation levels around the fuel ponds were extremely high and “potentially lethal” near the reactors.
In a sign that foreign governments were losing confidence in Japan’s ability to contain radioactivity from the crippled reactors, the embassies of Australia, China, South Korea, Thailand and other countries upgraded their warnings to nationals still in the country.
The US and UK governments on Thursday started arranging charter flights for their nationals to leave Japan. The UK and Australia also expanded the evacuation zone to 80km in line with US advice to its nationals.
Mr Edano said foreign governments were being “conservative” but added that he understood their caution.
“If we were in their position, we would naturally be doing the same thing,” he said.