Japan Fears Nuclear Reactor Is Leaking Contaminated Water

Highly contaminated water is escaping a damaged reactor at the crippled nuclear power plant in Japan and could soon leak into the ocean, the country’s nuclear regulator warned on Monday.

Japanese soldiers searched Sunday for victims in Kesennuma. Japan’s national police said that the death toll had risen to 10,668 and that 16,574 were missing.

The discovery raises the danger of further radiation leaks at the Fukushima Daiichi Nuclear Power Station and is a further setback to efforts to contain the nuclear crisis as workers find themselves in increasingly hazardous conditions.

Radiation measuring 1,000 millisieverts per hour was detected in water in an overflow tunnel outside the plant’s Reactor No. 2, Japan’s nuclear regulator said at a news conference. The maximum dose allowed for workers at the plant is 250 millisieverts in a year.

The tunnel leads from the reactor’s turbine building, where contaminated water was discovered on Saturday, to an opening just 180 feet from the sea, said Hidehiko Nishiyama, deputy director-general for the Nuclear and Industrial Safety Agency.

The contaminated water level is now about three feet from the exit of the vertical, U-shaped tunnel and rising, Mr. Nishiyama said.

Contaminated water was also found at tunnels leading from the No. 1 and No. 3 reactors, though with much lower levels of radiation.

“We are unsure whether there is already an overflow” of the water out of the tunnel, Mr. Nishiyama said. He said workers were redoubling efforts to first remove the water from the Reactor No. 2 turbine building. Government officials have said that the water is probably leaking from broken pipes inside the reactor, from a breach in the reactor’s containment vessel or from the inner pressure vessel that houses the nuclear fuel.

The nuclear safety agency also reported that radioactive iodine 131 was detected Sunday at a concentration 1,150 times the maximum allowable level in a seawater sample taken about a mile north of the drainage outlets of reactor units 1 through 4. It also said that the amount of cesium 137 found in water about 1,000 feet from plant was 20 times the normal level, roughly equal to readings taken a week ago.

Mr. Nishiyama said there were no health concerns because fishing would not be conducted in the evacuation-designated area within about 12 miles of the plant, the Kyodo news agency reported.

Monday’s disclosure about the escaping contaminated water came as workers pressed their efforts to remove highly radioactive water from inside buildings at the plant. The high levels of radioactivity have made it harder for them to get inside the reactor buildings and control rooms to get equipment working again, slowing the effort to cool the reactors and spent fuel pools.

Workers pumped less water into the reactors Monday in an attempt to minimize the overflow of radioactive water from them, slowing down the cooling process, Tokyo Electric Power Company, the operator of the plant, said.

The company said the elevated radiation levels in the water, which flooded the turbine buildings adjacent to the reactors, were at least four times the annual permissible exposure levels for workers at the plant and 100,000 times greater than ordinarily found in water at a nuclear facility.

Alarm over the radiation levels grew last Thursday when two workers were burned around their feet and ankles after they stepped into highly radioactive water inside the turbine building of Reactor No. 3. A third worker who was wearing higher boots did not suffer the same exposure. Japanese news media reported that the three workers were released from the hospital on Monday.

Over the weekend a worker trying to measure radiation levels of the water at Reactor No. 2 saw the reading on his dosimeter jump beyond 1,000 millisieverts per hour and left the scene immediately, said Takeo Iwamoto, a spokesman for Tokyo Electric Power.

Under normal conditions the average amount of radiation workers at the plant are allowed to be exposed to is at most 50 millisieverts a year. In emergency situations the limit is usually raised to 100 millisieverts but it has been raised to 250 millisieverts during the crisis.

There was no evacuation of the workers stationed at Daiichi after the high radiation levels were discovered. Naoki Sunoda, a spokesman for Tokyo Electric Power, said that since the crisis began on March 11, 19 workers had been exposed to radiation levels of 100 millisieverts. Of the workers at the site on Monday, 381 were from Tepco and 69 from a contractor. Firefighters and members of the Japanese military have also been helping at the plant.

Despite the new problem, Mr. Sunoda said, workers on Monday were still trying to determine a way to approach the turbine building of Reactor No. 2 to extract the contaminated water.