Tokyo -(Reuters/NAN) Smoke and steam rose from two of the most threatening reactors at Japan’s quake-crippled nuclear plant on Tuesday, suggesting the battle to avert a meltdown and the spread of radiation was far from won.

The world’s worst nuclear crisis in 25 years was triggered by a huge earthquake and tsunami on March 11 that left at least 21,000 people dead or missing.

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.

Kyodo news agency said steam appeared to rise from reactor No. 2 and white haze was detected above reactor No. 3.

There have been several blasts of steam from the reactors during the crisis, which experts say probably released a small amount of radioactive particles.

Plant operator Tokyo Electric Power Co (TEPCO) said later the smoke had turned to steam and it was deemed safe to continue work in bringing the plant under control.

“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.

Reuters earlier reported that the Fukushima plant was storing more uranium than it was originally designed to hold and that it had repeatedly missed mandatory safety checks over the past decade, according to company documents and outside experts.

Questions have also been raised about whether TEPCO officials waited too long to pump sea water into the reactors and abandon hope of saving the equipment in the aftermath of the earthquake and tsunami.

Away from the plant, mounting evidence of radiation in vegetables, water and milk stirred concerns among Japanese and abroad despite officials’ assurances that the levels were not dangerous.

TEPCO said radiation was found in the Pacific Ocean nearby, not surprising given rain and the hosing of reactors with seawater.

TEPCO officials have said some of the water from the hosing was spilling into the sea.

Radioactive iodine in the sea samples was 126.7 times the allowed limit, while caesium was 24.8 times over, Kyodo 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.

“ People are generally exposed to about one to 10 millisieverts each year from background radiation caused by substances in the air and soil,’’ he added.

Japan has urged some residents near the plant to stop drinking tap water after high levels of radioactive iodine were detected.

 It has also stopped shipments of milk, spinach and a vegetable called kakina from the area, the plant lies 240 km North of Tokyo.

Experts say readings are much lower than around Chernobyl after the 1986 accident in Ukraine.

Japan is a net importer of food but it also exports fruit, vegetables, dairy products and seafood, with its biggest markets in Hong Kong, China and the U.S.

 China said it was monitoring food imports from Japan and South Korea is expanding inspection of Japanese food.