The struggle to shut down crippled reactors at the Fukushima Daiichi nuclear plant remains compromised by highly contaminated water poured into reactors and spent-fuel pools that now has leaked into other parts of the complex, threatening workers, Japanese authorities said Tuesday.

No major progress was reported by Tokyo Electric Power Co. (TEPCO) in transferring massive volumes of seawater and freshwater from the condensation pools and tunnels in and around the turbine buildings near the reactors, NHK World reported Tuesday from Japan. The water leaked from reactor buildings during the emergency cooling operations following the March 11 earthquake and tsunami.

TEPCO workers pumped some water out of the turbine condenser for reactor No. 1 on Monday, but the plant owner gave no report on how much was removed. It plans to drain basements at units 2 and 3, transferring water into the condenser pools of other undamaged reactors at the site, but those condensers must be emptied first, NHK said.

"They have a huge amount of radioactively contaminated water," said David Lochbaum, head of the nuclear safety project for the Union of Concerned Scientists yesterday, in a briefing for reporters.

"The pathways for that material to get out are numerous. For example, the reactor buildings for units 1, 3 and 4 are no longer intact, so they're no longer acting as a barrier to reduce the contamination that may leave as it evaporates from the puddles on the floor in various buildings," he said.

"They need to get some control over that, some place to put it, some processing plant that can treat the water, remove as much radiation as possible from the water," he continued. "They had to use the water ... to cool the spent-fuel pools and the reactors, but the legacy of that need has been a huge problem that they need to get their arms around quickly."

Radioactivity-contaminated water has leaked into tunnels leading from the reactors, Japanese authorities said. Although the tunnels apparently do not open directly to the sea, according to authorities, contaminated water that overflows the tunnels could drain into the ocean. Yesterday workers placed sandbags and poured concrete around the tunnel mouths to prevent drainage.

The Nuclear and Industrial Safety Agency said TEPCO must balance the injection of cooling water into the reactors with the need to prevent radioactive water from leaking out and threatening workers or causing additional contamination outside the plant, news reports said.

Attempt to reduce water injection poses problems

TEPCO reduced water injection at the Unit 1 reactor but recorded an increase in the reactor surface temperature from 213 degrees Celsius early Monday to 329 degrees early today. A normal temperature reading would be 302 degrees, NHK reported. TEPCO has since increased water injection, reducing the heat buildup, the news agency said.

TEPCO said sampling over the weekend detected the presence of iodine-131 in seawater outside the plant at levels more than 1,000 times higher than the regulated limit, .

Technicians have found plutonium, a carcinogen, in the soil around the plant, assumed to have come from the reactor fuel in reactor No. 3, the only one of the three damaged reactors that was using MOX fuel that includes plutonium. The Nuclear and Industrial Safety Agency said yesterday the plutonium level did not threaten workers at the site or public health in the surrounding area.

The Nuclear Energy Institute reported on its website that it is still too early to reach conclusions about concentrations of radioactivity in marine food, citing the International Atomic Energy Agency. "The latest sampling shows that drinking water in Fukushima and Ibaraki prefectures remain below the Japanese limits for the ingestion of drinking water by infants. Iodine-131 was reported in food samples taken from March 26 to March 27 in six prefectures (Fukushima, Gunma, Ibaraki, Niigata, Tochigi and Yamagata) in vegetables, strawberries and watermelon," NEI, the U.S. nuclear industry's principal organization, said.

Two workers who were hospitalized for radiation exposure after standing in contaminated water for two hours while laying electric cables around Unit 3 were released yesterday from the National Institute of Radiological Sciences. An institute physician told reporters they and a third worker exposed to radiation should not suffer health consequences.

Edwin Lyman, senior scientist at the Union of Concerned Scientists, said yesterday that instruments at the plant have been providing questionable and inconsistent readings. "Without having a good, accurate program for monitoring radiation levels in all these various areas, it's hard to see how they can actually implement a program for protecting the workers adequately."

TEPCO said it has detected radiation exposures of more than 1,000 millisieverts per hour in puddles in the Unit 2 turbine building and in a trench outside the building.

"Some people point out that's four times the workers' allowed dose for the year under these emergency conditions. But it's worse than that, because at that rate, acute effects and symptoms could show up within an hour, a little more than an hour after being exposed to those levels. So, it's not simply the cumulative effect and the impact on the workers' risk of cancer, but it's also the rate where they may suffer acute symptoms, and that would take things to another level," Lyman said yesterday.