By Kiyoshi Takenaka and Yoko Nishikawa
TOKYO (Reuters) - Japan's nuclear crisis stretched to three weeks on Friday with radiation widening from a crippled power plant and scant hope of a quick resolution.
France -- the most nuclear-dependent in the world -- called for new global nuclear rules and proposed a global conference in France for May as President Nicolas Sarkozy paid a quick visit to Tokyo on Thursday to show support.
"We must look at this coldly so that such a catastrophe never occurs again," said Sarkozy, who chairs the Group of 20 bloc of nations, during his brief stopover.
It was the first visit by a foreign leader since a March 11 earthquake and tsunami battered northeast Japan, leaving nearly 28,000 people dead or missing. The damage may top $300 billion (187 billion pounds), making it the world's costliest natural disaster.
Prime Minister Naoto Kan, under enormous pressure as he struggles to manage Japan's toughest test since World War II, welcomed the gesture of solidarity.
"I told him a Japanese proverb -- 'a friend who comes on a rainy day is your true friend', and thanked him for coming to Japan from the bottom of my heart," he said.
Illustrating the gravity of the problem and spreading contamination, radioactive iodine 131 was found in ground water near No.1 reactor of Fukushima Daiichi complex, plant operator Tokyo Electric Power Co (TEPCO) said.
"Radioactive materials in the air could have come down to the earth's surface and they could have seeped into the ground due to rainfall," a company spokesman said.
Radiation in water at an underground tunnel near another reactor of the plant had also been found more than 10,000 times above the normal level of water in reactors, Kyodo news agency said.
An abnormal level of radioactive caesium appeared in beef from the area for the first time, but Japan's nuclear safety agency wants to test it again as it had some doubts over test results, Kyodo added.
ROBOTS
France is a global leader in the nuclear industry, and Paris has flown in experts from state-owned nuclear reactor maker Areva to work with Japanese engineers.
"Areva is one of the companies that will make the most out of a nuclear revival and therefore will be in most trouble if there isn't a nuclear revival," said Malcolm Grimston, an expert from London's Imperial College.
"Certainly Sarkozy or France generally have a very strong interest in getting things moving as quickly as possible and trying to ensure that there isn't a major backlash (to nuclear power). France would be one of the biggest losers from that."
Other nations are also scrambling to help Japan.
The United States and Germany are sending robots to help repair and explore the damaged Fukushima Daiichi plant. Kyodo said some 140 U.S. military radiation safety experts would soon visit to offer technical help.
The International Atomic Energy Agency (IAEA), which says the situation at the Fukushima plant remains very serious, already has two teams in Japan, monitoring radiation levels.
The Japanese disaster, the worst nuclear accident since Chernobyl in 1986, has appalled the world and revived heated debate over the safety and benefits of atomic power.
The controversy took an alarming twist in Switzerland when a parcel bomb exploded at the office of the national nuclear lobby, injuring two employees. It was not known who sent it.
Japan's Kan is under pressure to expand a 20-km (12-mile) evacuation zone around the plant, where radiation has also hit 4,000 times the legal limit in the nearby Pacific sea.
Worryingly, the source of the leak is unclear.
More than 70,000 people have been evacuated from the 20-km ring. Another 136,000 who live in a 10-km (6-mile) band beyond that have been encouraged to leave or to stay indoors.
The U.N. atomic agency IAEA said radiation at a village 40 km (25 miles) away exceeded a criterion for evacuation, while the head of a group of independent radiation experts said Japan must hand out iodine tablets now and as widely as possible to avoid a potential leap in thyroid cancers.
"CANNIBALISATION"
Underlining the terrible and surreal times Japan is living, one newborn baby's first medical appointment was not with a paediatrician -- but a Geiger counter.
"I am so scared about radiation," Misato Nagashima said as she took her baby Rio, born four days after the earthquake and disaster, for a screening at a city in Fukushima prefecture.
Trade Minister Banri Kaieda said chickens and pigs left behind by farmers in the evacuation zone were resorting to desperate means. "A considerable amount of time has passed and I am hearing there were episodes of cannibalisation," he said.
Government officials are pleading for Japanese, and the world, to avoid overreacting to what they say are still low-risk levels of radiation away from the plant.
Food and milk shipments from the region have been stopped, decimating the livelihoods of farmers and fishermen. Various nations have banned food imports from the area.
Contaminated milk was one of the biggest causes of thyroid cancer after the 1986 nuclear accident in Chernobyl because people near the plant kept drinking milk from local cows.
Experts say the battle to control Fukushima's six reactors by restoring pumps to cool fuel could take weeks, if not months, followed by a clean-up operation that may drag on for years.
"In order to shut down the immediate public health risk, it's necessary to transition from interim cooling to a longer term cooling solution, stop leakage of radioactive liquids, and decontaminate or remove radioactive materials in and around the facilities," said Eric Moore of U.S.-based FocalPoint Consulting group.
"This could take 6 months to a year, or longer if the radioactive materials are very dispersed."
TEPCO could face compensation claims of up to 11 trillion yen (82 billion pounds), nearly four times its equity, according to one analyst.
Decommissioning the four worst-affected reactors could take more than a decade and cost about $10-19 billion, experts say.
(Additional reporting by Chisa Fujioka and Kiyoshi Takenaka in Tokyo, Fredrik Dahl in Vienna, Scott DiSavino in New York, Catherine Bremer in Paris; Writing by Andrew Cawthorne; Editing by Alex Richardson)
