TOKYO (Reuters) - Japan will have to review its nuclear power policy, its top government spokesman said on Thursday as radiation from a damaged nuclear complex briefly made Tokyo's tap water unsafe for babies and led to people emptying supermarket shelves of bottled water.
Engineers are trying to stabilize the six-reactor nuclear plant in Fukushima, 250 km (150 miles) north of the capital, nearly two weeks after an earthquake and tsunami battered the plant and devastated northeastern Japan, leaving nearly 26,000 people dead or missing.
"It is certain that public confidence in nuclear power plants has greatly changed," Japanese Chief Cabinet Secretary Yuki Edano told Reuters.
"In light of that, we must first end this situation and then study from a zero base."
Before last week, Japan's 55 nuclear reactors had provided about 30 percent of the nation's electric power. The percentage had been expected to rise to 50 percent by 2030, among the highest in the world.
There were no fresh incidents of smoke or steam at the plant on Thursday, but four of the plant's reactors are still considered volatile, although on the way to stability.
"It's still a bit early to make an exact time prognosis, but my guess is in a couple of weeks the reactors will be cool enough to say the crisis is over," said Peter Hosemann, a nuclear expert at the University of California, Berkeley.
"It will still be important to supply sufficient cooling to the reactors and the spent fuel pools for a longer period of time. But as long as this is ensured and we don't see any additional large amount of radioactivity released, I am confident the situation is under control."
Tokyo's 13 million residents were told not to give tap water to babies under 1 year old after contamination hit twice the safety level this week. But it dropped back to allowable amounts on Thursday.
Despite government appeals against panic, many supermarkets and stores sold out of bottled water.
"Customers ask us for water. But there's nothing we can do," said Masayoshi Kasahara, a store clerk at a supermarket in a residential area of eastern Tokyo. "We are asking for more deliveries but we don't know when the next shipment will come."
Radiation above safety levels has also been found in milk and vegetables from Fukushima and the Kyodo news agency said radioactive cesium 1.8 times higher than the standard level was found in a leafy vegetable grown in a Tokyo research facility.
Singapore said it had found radioactive contaminants in four samples of vegetables from Japan.
Earlier, it and Australia joined the United States and Hong Kong in restricting food and milk imports from the zone, while Canada became the latest of many nations to tighten screening after the world's worst nuclear crisis since Chernobyl.
A shipping industry official, meanwhile, said some merchant vessels may be avoiding Tokyo port due to concern that crew members may be exposed to radiation.
Radiation particles have been found as far away as Iceland, and although Japan insists levels are not dangerous to adults, it is the nation's most testing time since world War Two.
The estimated $300 billion damage from the 9.0 magnitude earthquake and ensuing tsunami makes it the world's costliest natural disaster, dwarfing Japan's 1995 Kobe quake and Hurricane Katrina, which swept through New Orleans in 2005.
In Japan's north, more than a quarter of a million people are in shelters. Some elderly displaced people have died from cold and lack of medicines.
Exhausted and traumatized rescuers are still sifting through the mud and wreckage where towns and villages once stood.
The official death toll from the disaster has risen to 9,523, but is bound to rise as 16,094 people are still missing.
Amid the suffering, though, there was a sense that Japan was turning the corner in its humanitarian crisis. Aid flowed to refugees, and phone, electricity, postal and bank services began returning to the north, sometimes by makeshift means.
"Things are getting much better," said 57-year-old Tsutomu Hirayama, staying with his family at an evacuation center in Ofunato town.
"For the first two or three days, we had only one rice ball and water for each meal. I thought, how long is this going to go on? Now we get lots of food, it's almost like luxury."
Aftershocks are still jolting the country. Several shook Tokyo on Thursday.
ADMIRATION FOR NUCLEAR WORKERS
At the Fukushima plant, technicians have successfully attached power cables to all six reactors and started a pump at one to cool overheating fuel rods.
Nearly 300 engineers, fast becoming national heroes for braving danger inside an evacuation zone, are fighting to cool fuel rods at the reactors.
They resumed work on Thursday at the No.3 reactor, considered the most critical, after a one-day suspension when black smoke was seen rising.
Operator Tokyo Electric Power Co (TEPCO) (9501.T) is trying to re-start systems to keep the fuel cool and prevent further radiation leaks or a complete meltdown, the nightmare scenario.
Three TEPCO employees who were working in water to connect a cable were injured by radiation on Thursday and two were taken to hospital with burns, the nuclear safety agency said.
Japan has urged the world not to overreact, and plenty of experts appeared to back that up.
Jim Smith, of Britain's University of Portsmouth, said the finding of 210 becquerels of radioactive iodine, twice the safety limit, at a Tokyo water purification plant on Wednesday should not be cause for panic. The safety level for adults is 300 becquerels.
"The recommendation that infants are not given tap water is a sensible precaution. But it should be emphasized that the limit is set at a low level to ensure that consumption at that level is safe over a fairly long period of time," he said.
"This means that consumption of small amounts of tap water -- a few liters, say-- at twice the recommended limit would not present a significant health risk."
The crisis in the world's third-biggest economy -- and its key position in global supply chains, especially for the automobile and technology sectors -- has added to jitters in global financial markets, also worried by conflict in Libya and Middle East protests.
Toyota Motor Corp (7203.T) (TM.N), which has suspended production at all of its 12 assembly plants in Japan, said it would slow some North American production because of supply problems although it would try to minimize disruptions.