By Julie Makinen and Thomas H. Maugh II, Los Angeles Times
April 3, 2011, 7:51 a.m.
Reporting from Tokyo and Los Angeles— 
Workers at theFukushima Daiichi nuclear power plant failed for a second day to stem the flow of radioactive water into the ocean as plastic injected into the leak Sunday failed to form a plug.

Workers had discovered an 8-inch crack in a concrete channel at the lower levels of reactor No. 2 where radioactive water had been accumulating after it had been sprayed onto the reactor to cool it. The crack was spewing the contaminated water into the ocean, which may explain the high levels of radioactivity detected offshore near the plant.

On Saturday, workers attempted to pump concrete into the crack to seal it, but the concrete would not set before it was washed away by the flow of seawater.

On Sunday, engineers attempted to plug the leak with a mixture of sawdust, shredded paper and a polymer or plastic that expanded to 500 times its normal size when exposed to water. They had then hoped to pour concrete on top of the polymer to form a permanent seal, but the polymer did not form a plug either, and as of Sunday night, water was continuing to flow into the ocean.

Radiation levels in the water are an estimated 1,000 millisieverts per hour, a high but not immediately lethal dose.

On Monday, engineers plan to begin injecting nitrogen gas into reactors Nos. 1, 2 and 3 in an attempt to prevent possible explosions from the buildup of hydrogen gas. The nonflammable nitrogen would dilute both oxygen levels and any hydrogen that accumulated from deterioration of the uranium fuel cladding. The zirconium cladding on the fuel rods becomes oxidized when it is exposed to hot water, releasing hydrogen gas.

Explosions at the three reactors in the first four days after the magnitude 9 Tohoku earthquake and the accompanying tsunami badly damaged the reactor buildings and destroyed the cooling pumps that provided water to the reactors.

An aide to Japanese Prime Minister Naoto Kan and a spokesman for the country's nuclear safety agency both said Sunday that they expected it would take months to resolve the situation at the power plant. "It would take a few months until we get things under control and have a better idea about the future," Hidehiko Nishiyama of the safety agency said in a news conference.

Officials of the Tokyo Electric Power Co. said Sunday that they had retrieved two bodies from the power plant last Wednesday. The men had rushed into the control room during the earthquake and were killed in the tsunami that followed.

The announcement of their recovery was not made until Sunday so that the families could be notified first.

A search by Japanese and U.S. military authorities on Sunday led to the discovery of 70 more bodies of people who died in the tsunami, bringing the official death total to 12,087, with more than 15,500 still missing or unaccounted for.

thomas.maugh@latimes.com

julie.makinen@latimes.com