The military also announced that it had postponed plans to drop water on Reactor No. 4, which Gregory Jaczko, the chairman of the United States Nuclear Regulatory Commission, on Wednesday pinpointed as a cause for serious alarm.
On Thursday afternoon, the Self-Defense Forces and the Tokyo Metropolitan Police had begun deploying eight water cannon trucks to Reactor No. 3. Before the radiation level drove them back, the Tokyo Metropolitan Police had planned to use the trucks, which are usually used in riot control, to spray at least 12 tons of seawater into the reactor.
The Self-Defense Forces planned to send five fire trucks, carrying a total of 30 tons of seawater. The Japanese government said that the reactor typically needs 50 tons of water a day to keep from overheating.
Tokyo Electric Power Company, which operates the reactors, was also working to complete a high-power line to the plant to restore the electricity needed to run the cooling systems, according to a senior Japanese nuclear industry executive.
The maneuvers seemed at odds with the most startling assertion by Mr. Jaczko that there was now little or no water in the pool storing spent nuclear fuel at the No. 4 reactor, leaving fuel rods stored there exposed and bleeding radiation into the atmosphere. His testimony before Congress was the first time the Obama administration had given its own assessment of the condition of the plant, apparently mixing information it had received from Japan with data it had collected independently. “We believe that radiation levels are extremely high, which could possibly impact the ability to take corrective measures,” Mr. Jaczko said.
His statement was quickly but not definitively rebutted by officials of Tokyo Electric, the plant’s operator.
“We can’t get inside to check, but we’ve been carefully watching the building’s environs, and there has not been any particular problem,” Hajime Motojuku, a spokesman for Tokyo Electric, said Thursday morning in Japan.
Later, a spokesman for Japan’s Nuclear and Industrial Safety Agency, Yoshitaka Nagayama, was more equivocal, saying, “Because we have been unable to go to the scene, we cannot confirm whether there is water left or not in the spent fuel pool at Reactor No. 4.”
At the same time, officials raised concerns about two other reactors where spent fuel rods were stored, Nos. 5 and 6, saying they had experienced a slight rise in temperature.
On Wednesday night, Mr. Jaczko reiterated his earlier statement and added that commission representatives in Tokyo had confirmed that the pool at No. 4 was empty. He said Tokyo Electric and other officials in Japan had confirmed that, and also stressed that high radiation fields were going to make it very difficult to continue having people work at the plant.
