|Technicians working inside an evacuation zone around the plant have attached power cables to all reactors [Reuters]
Workers battling to repair the Fukushima Daiichi nuclear plant in Japan were briefly evacuated after clouds of what was thought to be either smoke or steam were seen rising from the quake-stricken complex.
Plant operator Tokyo Electric Power Co (TEPCO) later said on Tuesday that the smoke had turned to steam and it was deemed safe to continue work in bringing the plant under control.
Japan's nuclear safety agency said steam was believed to be coming off a spent nuclear fuel pool at reactor No.2, and white haze was detected above reactor No. 3.
Al Jazeera's Andrew Thomas, reporting from the city of Morioka, said it remained unclear on Tuesday morning what had caused the smoke.
"TEPCO, the company that runs the plant, say they're not too concerned," he said. "They say radiation levels seem to be stable and that smoke may just have been a bit of an aberration."
"Things are beginning to trend in the right direction. TEPCO will need to get electrical power back on line to all six reactors and they will have to make sure that components are working," said Mark Prelas, director of research for the Nuclear Science and Engineering Institute at the University of Missouri.
Technicians working inside an evacuation zone around the stricken plant on Japan's northeast Pacific coast have attached power cables to all six reactors and started a pump at one of them to cool overheating nuclear fuel rods.
There have been several blasts of steam from the reactors since a massive quake followed by a deadly tsunami damaged their cooling functions, resulting in radiation leaks.
In the days since the twin disasters struck on March 11, the reactors have overheated and some explosions have occurred.
"Our crisis is still going on. Our crisis is with the nuclear plants. We are doing everything we can to bring this to an end," Yuhei Sato, governor of Fukushima prefecture, said. Radiation fears from the plant have forced the authorities to move about 1,400 people from areas around the plant to a gymnasium 80km away.
Growing concerns about radiation add to the chain of disasters Japan has struggled with since the 9.0-magnitude quake devastated the country.
There is mounting evidence of radiation in vegetables, water and milk causing the government to ban sale of raw milk, spinach and canola from prefectures over a swathe of land from the plant towards Tokyo.
|The quake-triggered tsunami left
more than 350,000 homeless [GALLO/GETTY]
The government has also started to test fish and shellfish.
TEPCO also said a small trace of radiation had been found in the Pacific sea waters nearby.
Radioactive iodine in the sea samples was 126.7 times the allowed limit, while caesium was 24.8 times over, Kyodo news agency said. That still posed no immediate danger, TEPCO said.
"It would have to be drunk for a whole year in order to accumulate to one millisievert," a TEPCO official said,
referring to the standard radiation measurement unit.
China, Japan's biggest trading partner, ordered testing of Japanese food imports for radiation contamination and the World Health Organisation (WHO) said Japan will have to do more to reassure the public about food safety.
"They're going to have to take some decisions quickly in Japan to shut down and stop food being used completely from zones which they feel might be affected," Gregory Hartl, a WHO spokesman, said.
WHO said Japan needs to act quickly and ban food sales from areas around the damaged Fukushima nuclear plant if the food there is found to contain excessive levels of radiation.
Death toll rising
Damage from the earthquake and tsunami is estimated at $250bn, making it the world's costliest natural disaster.
The official death toll has exceeded 9,000 but with 12,654 people reported missing, it is certain to rise.
The quake and tsunami obliterated towns, which are now wastelands of mud and debris, leaving more than 350,000 people homeless.
Japanese are famed for resilience, though, and there was none of the chaos or looting that major disasters often spark.
In one devastated northern town, Rikuzentakata, rebuilding has begun. Steel structures, with walls and wood floors, have been erected at a hilltop school, to provide temporary housing.