Japanese officials are reporting the highest radiation readings yet near a troubled power plant since a tsunami set off the nation’s nuclear crisis nearly three weeks ago.

Officials say seawater outside of the Fukushima Dai-ichi nuclear power plant contains more than 3,300 times the normal amount of radioactive iodine. The country’s nuclear safety agency says it’s a “concern” — but not necessarily an immediate threat. Officials say they are exploring a variety of new ways to contain the radioactive water seeping out of the plant.

The International Atomic Energy Agency has said that it expects radiation levels in seawater to drop as it dilutes and that radiation in seafood will most likely not reach levels above established limits for consumption if Tokyo Electric Power Co., which owns the plant, can stop the discharges of contaminated seawater.

On Wednesday, Tsunehisa Katsumata, chairman of TEPCO, said the company’s president, Masataka Shimizu, who has not been seen in public since a March 13 news conference in Tokyo, had fallen ill and last night was checked into hospital.

Shimizu’s disappearance has created speculation that he suffered a breakdown. For days, officials deflected questions about his whereabouts, saying he was “resting” at company headquarters.

Katsumata also said the units 1 through 4 reactors at Fukushima Dai-ichi will have to be scrapped because of damage and radiation risks. A government spokesman later said units 5 and 6, which have been in cold shutdown, will also have to be decommissioned.

Managing Water Woes

Meanwhile, officials are considering several ways to contain radioactive materials coming from the damaged nuclear power plant. NPR’s Jon Hamilton says the goal is to prevent further contamination of the air and ocean.

The latest hardship of getting the reactors and spent fuel pools under control has been leaks of highly radioactive substances from the reactors. On Monday, water was found in underground tunnels and trenches that run below and outside of the nuclear reactors, near three buildings that house massive steam turbines at the coastal nuclear complex. Highly radioactive water has also flooded the basements of the turbine buildings.

Complicating matters, the tanks storing the contaminated water are beginning to fill up. Pumping at one unit has been suspended since Tuesday night while workers scramble to drain a new tank after the first one reached capacity. And the water woes compounded Wednesday, when workers discovered a new location where it is pooling.

At a news conference Wednesday, a spokesman for the government described several possible measures to deal with the tens of thousands of gallons of contaminated water accumulating in the basements, tunnels and trenches.

The plan for Thursday is to use an unmanned, remote-controlled vehicle to spray resin over debris “on a trial basis.” The water-soluble resin would ideally prevent the spread of radiation leaks.

Another idea under consideration to manage the radioactive water leaking out of the reactors is to pump it into a tanker offshore. Officials are also considering temporarily storing the water in a waste disposal facility at the plant.

The spokesman mentioned another idea intended to keep radioactive particles from getting into the atmosphere: Workers would cover damaged reactor buildings with a special fabric that would act as a filter.

Radiation Hinders Search For The Dead

The ongoing nuclear crisis is hampering efforts to find the dead and missing near the crippled Fukushima Dai-ichi power plant, NPR’s Jason Beaubien reports from Fukushima City.

Three coastal villages near the plant used to be home to more than 30,000 people. The tsunami wiped out entire neighborhoods in them, yet only five people from the towns closest to the facility have been confirmed dead.

Residents have been ordered to stay at least 12 miles away from the leaking nuclear complex. Japanese soldiers and police in protective clothing have launched limited searches into the nearby towns, but their work has been hampered by elevated levels of radiation. At times they’ve had to pull out of the area altogether.

Radiation around the crippled nuclear plant has been fluctuating. On Tuesday officials reported that radiation levels in both the air and the sea were going down.

With reporting by NPR’s Jon Hamilton in Tokyo and Jason Beaubien in Fukushima City. The Associated Press contributed material to this report. Copyright 2011 National Public Radio. To see more, visit http://www.npr.org/.