* Some progress in trying to stabilise reactors

* Radiation traces found in food and water

* Quake and tsunami give Japan vast rebuilding task

* More than 7,500 dead, 11,700 missing

Engineers enjoyed some success in their mission to stop disaster at Japan's tsunami-damaged power plant, though evidence of small radiation leaks highlighted perils from the world's worst nuclear crisis since Chernobyl 25 years ago.

Three hundred technicians have been battling inside a danger zone to salvage the six-reactor Fukushima plant since it was hit by an earthquake and tsunami that also killed 7,508 people and left 11,700 more missing in northeast Japan.

The unprecedented multiple crisis will cost the world's third largest economy nearly $200 billion in Japan's biggest reconstruction push since post-World War II.

It has also set back nuclear power plans the world over.

Encouragingly for Japanese transfixed on the work at Fukushima, the situation at the most critical reactor -- No. 3 which contains highly toxic plutonium -- appeared to come back from the brink after fire trucks doused it for hours.

Work also advanced on bringing power back to water pumps used to cool overheating nuclear fuel.

"We are making progress ... (but) we shouldn't be too optimistic," said Hidehiko Nishiyama, deputy-general at Japan's Nuclear Safety Agency.

Engineers attached a power cable to the No.1 and No. 2 reactors, hoping to restore electricity later in the day. They also hope to reach No. 3 and 4 soon to test turning the pumps on.

If successful, that could be a turning point in a crisis already rated as bad as America's Three Mile Island accident in 1979. If not, drastic measures may be required such as burying the plant in sand and concrete as happened at Chernobyl after the world's worst nuclear reactor disaster in 1986.

Cooling systems have been restored at the least critical of the six reactors, No. 5 and 6, using diesel generators.

"It appears that the situation has somewhat stabilised but it is still very severe," said Bo Stromberg, an analyst at the Swedish Radiation Safety Authority.

On the negative side, evidence has begun emerging of radiation leaks from the plant, including into food and water.

Though public fear of radiation runs deep, and anxiety has spread as far as the Pacific-facing side of the United States, health officials say levels so far are not alarming.

Traces exceeding national safety standards were, though found in milk from a farm about 30 km (18 miles) from the plant and spinach grown in neighbouring Ibaraki prefecture.