Tokyo ? A possible breach at Japan’s troubled nuclear plant has escalated the crisis anew, two full weeks after an earthquake and tsunami first compromised the facility. The development suggested radioactive contamination may be worse than first thought, with tainted groundwater the most likely consequence.

Japanese leaders defended their decision not to evacuate people from a wider area around the plant, insisting they are safe if they stay indoors. But officials said residents may want to voluntarily move to areas with better facilities, since supplies in the tsunami-devastated region are running short.

The escalation in the nuclear plant crisis came as the death toll from the quake and tsunami passed 10,000. Across the battered northeast coast, hundreds of thousands of people whose homes were destroyed still have no power, no hot meals and, in many cases, no showers for two weeks.

Nuclear problems

The uncertain nuclear situation delayed efforts to stop the overheated Fukushima Dai-ichi nuclear plant from leaking dangerous radiation.

Work was under way today to inject fresh water into one unit, said Hidehiko Nishiyama, a spokesman for Japan’s Nuclear and Industrial Safety Agency, or NISA, amid concerns about dumping large amounts of potentially corrosive seawater onto the reactors.

Low levels of radiation have been seeping out since the March 11 quake and tsunami knocked out the plant’s cooling system, but a breach could mean a much larger release of contaminants. The most likely consequence would be contamination of the groundwater.

“The situation today at the Fukushima Dai-ichi power plant is still very grave and serious. We must remain vigilant,” a somber Prime Minister Naoto Kan said Friday night. “We are not in a position where we can be optimistic. We must treat every development with the utmost care.”

The possible breach in the plant’s Unit 3 might be a crack or a hole in the stainless steel chamber of the reactor core or in the spent fuel pool that’s lined with several feet of reinforced concrete. The temperature and pressure inside the core, which holds the fuel rods, remained stable and was far lower than what would further melt the core.

Suspicions of a possible breach were raised when two workers suffered skin burns after wading into water 10,000 times more radioactive than levels normally found in water in or around a reactor, NISA said.

Water with equally high radiation levels was found in the Unit 1 reactor building, Tokyo Electric Power Co. officials said. Water was also discovered in Units 2 and 4, and the company said it suspects that, too, is radioactive. Officials acknowledged the water would delay work inside the plant.

Radioactivity in seawater just outside one unit tested some 1,250 times higher than normal, probably from both airborne radiation released from the reactors and contaminated water leaked into the sea, Nishiyama said today.

But he said the amount posed no immediate health risk.

Radioactive water

Plant officials and government regulators say they don’t know the source of the radioactive water discovered at units 1 and 3 of the six-unit complex. It could have come from a leaking reactor core, associated pipes or a spent fuel pool. Or it may be the result of overfilling the pools with emergency cooling water.

The possible breach in the plant’s Unit 3 might be a crack or a hole in the stainless steel chamber of the reactor core or in the spent fuel pool that’s lined with several feet of reinforced concrete. The temperature and pressure inside the core, which holds the fuel rods, remained stable and was far lower than what would further melt the core.

Suspicions of a possible breach were raised when two workers suffered skin burns after wading into water 10,000 times more radioactive than levels normally found in water in or around a reactor, NISA said.

Elevated levels of radiation have turned up elsewhere, including the tap water in several areas of Japan. In Tokyo, tap water showed radiation levels two times higher than the government standard for infants, who are particularly vulnerable to cancer-causing radioactive iodine, officials said.

The scare caused a run on bottled water in the capital, and Tokyo municipal officials are distributing it to families with babies.

‘Worse than any movie’

The nuclear crisis has compounded the challenges faced by a nation already saddled with a humanitarian disaster. Much of the frigid northeast remains a scene of despair and devastation, with Japan struggling to feed and house hundreds of thousands of homeless survivors, clear away debris and bury the dead.

“It’s still like I’m in a dream,” said Tomohiko Abe, a 45-year-old machinist who was in the devastated coastal town of Onagawa trying to salvage any belongings he could from his ruined car. “People say it’s like a movie, but it’s been worse than any movie I’ve ever seen.”

The official death toll stood at 10,151 today, with more than 17,000 listed as missing, police said. With the cleanup and recovery operations continuing, the final number of dead was expected to surpass 18,000.