Tokyo – Amid widening alarm in the United States and elsewhere about Japan’s nuclear crisis, military fire trucks began spraying cooling water on spent fuel rods at the country’s stricken nuclear power station late Thursday after earlier efforts to cool the rods failed, Japanese officials said.
The United States’ top nuclear official followed up his bleak appraisal of the grave situation at the plant the day before with a caution that it would “take some time, possibly weeks,” to resolve.
The developments came as the authorities reached for ever more desperate and unconventional methods to cool damaged reactors, deploying helicopters and water cannons in a race to prevent perilous overheating in the spent rods of the No. 3 reactor.
Moments before the military trucks began spraying, police officers in water cannon trucks were forced back by high levels of radiation in the same area. The police had been trying to get within 50 yards of the reactor, one of six at the plant.
The five specially fitted military trucks sprayed water for about an hour, but the full impact of the tactic was not immediately clear.
The Japanese efforts focused on a different part of the Fukushima Daiichi Nuclear Power Station, 140 miles northeast of here, from the reactor — No. 4 — depicted in Washington on Wednesday as presenting a far bleaker threat than the Japanese government had offered.
The decision to focus on the No. 3 reactor appeared to suggest that Japanese officials believe it is a greater threat, since it is the only one at the site loaded with a mixed fuel known as mox, for mixed oxide, which includes reclaimed plutonium.
Western nuclear engineers have said that the release of mox into the atmosphere would produce a more dangerous radioactive plume than the dispersal of uranium fuel rods at the site. The Japanese authorities also expressed concern on Wednesday that the pressure in the No. 3 reactor had plunged and that either gauges were malfunctioning or a rupture had already occurred.
After the military’s effort to cool the spent fuel atop the reactor with fire trucks, Hidehiko Nishiyama, deputy director-general of the Nuclear and Industrial Safety Agency, said it was too early to assess the success of the attempt.
Mr. Nishiyama also said that radiation of about 250 millisievert an hour had been detected 100 feet above the plant. In the United States the limit for police officers, firefighters and other emergency workers engaged in life-saving activity as a once-in-a-lifetime exposure is equal to being exposed to 250 millisieverts for a full hour. The radiation figures provided by the Japanese Self-Defense Force may provide an indication of why a helicopter turned back on Wednesday from an attempt to dump cold water on a storage pool at the plant.
A White House statement late Wednesday said that President Obama had “briefed Prime Minister Kan on the additional support being provided by the U.S., including specialized military assets with expertise in nuclear response and consequence management.”
On Thursday a Pentagon spokesman, Col. David Lapan, said the military expertise made available to the Japanese included a nine-person assessment team that has or will shortly arrive there to work with the Japanese military and government.
The team members, Colonel Lapan said, will then recommend whether additional American military forces are needed to assist in the effort.
The American military is also gathering information on the damaged nuclear power plant. Officials said that a Global Hawk drone was flying missions over the reactor. In addition, U-2 spy planes were providing images to help the Japanese government map out its response to the quake and tsunami.
Earlier Thursday Japanese military forces tried to dump seawater from a helicopter on Reactor No. 3, making four passes and dropping a total of about 8,000 gallons as a plume of white smoke billowed. The Japanese government said that the reactor typically needs 50 tons of water, or about 12,000 gallons, a day to keep from overheating.
Video of the effort appeared to show most of the water missing the reactor and the Japanese military later said the measure had little effect on reducing the temperature in the pool where the spent rods are stored. A photograph from the air showed a light that seemed to suggest the presence of water in the pool, according to Tokyo Electric, but analysts said it was unclear what the image meant.
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, at a White House briefing, he issued the warning that resolving the situation could “take time, possibly weeks,” according to Bloomberg.
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 planned to use the trucks, which are usually used in riot control, to spray at least 12 tons of seawater into the reactor.
Tokyo Electric Power Company, which operates the reactors, was also working to restore the electricity needed to run the cooling systems. But the company said that the work was proceeding slowly and that it would be halted Friday morning to allow helicopters and trucks to resume pouring water on the reactor, Reuters reported.
Some of the maneuvers seemed at odds with the most startling assertion by Mr. Jaczko (pronounced YAZZ-koe) that there was 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 emphasized that high radiation fields were going to make it very difficult to continue having people work at the plant.
If the American analysis is accurate and emergency crews at the plant have been unable to keep the spent fuel at that inoperative reactor properly cooled — it needs to remain covered with water at all times — radiation levels could make it difficult not only to fix the problem at No. 4, but also to keep servicing any of the other problem reactors at the plant. In the worst case, experts say, workers could be forced to vacate the plant altogether, and the fuel rods in reactors and spent fuel pools would be left to melt down, leading to much larger releases of radioactive materials.
While radiation levels at the plant have varied tremendously, Mr. Jaczko said that the peak levels reported there “would be lethal within a fairly short period of time.” He added that another spent fuel pool, at Reactor No. 3, might also be losing water and could soon be in the same condition.
On Wednesday, the American Embassy in Tokyo, on advice from the Nuclear Regulatory Commission, told Americans to evacuate a radius of “approximately 50 miles” from the Fukushima plant. South Korea, Australia and New Zealand followed suit in advice to their citizens, and Spanish authorities on Thursday recommended an either wider berth, about 75 miles, news agencies reported. The advice to Americans in Japan represents a graver assessment of the risk in the immediate vicinity of Daiichi than the warnings made by the Japanese themselves, who have told everyone within 20 kilometers, about 12 miles, to evacuate, and those within about 20 miles to take shelter.
While maps of the plume of radiation being given off by the plant show that an elongated cloud will stretch across the Pacific, American officials said it would be so dissipated by the time it reached the West Coast of the United States that it would not pose a health threat.
Close to the site, however, Mr. Jaczko said, “We would recommend an evacuation to a much larger radius than has currently been provided by Japan.” That assessment seems bound to embarrass, if not anger, Japanese officials, suggesting they have miscalculated the danger or deliberately played down the risks.
Late Wednesday night the State Department announced what it described as a “voluntary” evacuation of dependents of American government personnel in northeastern Japan, and down to Tokyo and Yokohama. The undersecretary of state for administration, Patrick Kennedy, said that no one would be ordered to leave, but that the government would provide charter flights for dependents who wanted to leave.
On Thursday evening the American Embassy in Tokyo began offering seats aboard chartered flights to Americans wishing to evacuate from Japan. Americans who show up at the two main airports serving Tokyo, Narita and Haneda, would be flown to still unspecified “safe haven locations” from where they would be expected to arrange onward travel on their own, said Karen Kelley, a spokeswoman for the embassy.
The American move followed advisory notices from several European countries urging their citizens to move away from Tokyo or leave Japan altogether. On Thursday, Germany said it was moving its embassy operations from Tokyo to the southern city of Osaka, farther from the stricken plant.
American officials who have been dealing with their Japanese counterparts report that the country’s political and bureaucratic leadership has appeared frozen in place, unwilling to communicate clearly about the problem’s scope and, in some cases, unwilling to accept outside assistance. Two American officials said they believed that the Japanese government itself was not getting a clear picture from Tokyo Electric.
General Electric said it would send about 10 gas turbine generators to Japan to help replace lost power generating capacity. Michael Tetuan, a spokesman for the company, said that the operators of the damaged plant had requested generators, but he did not know what they would be used for. The units can produce roughly the same amount of power as the diesel generators at nuclear plants.
Though the plant’s reactors shut down automatically when the quake struck on Friday, the subsequent tsunami wiped out the backup electronic pumping and cooling system necessary to keep the fuel rods in the reactors and the storage pools for spent nuclear fuel covered with cool water.
Norimitsu Onishi reported from Tokyo, and David E. Sanger and Matthew L. Wald from Washington. Keith Bradsher contributed reporting from Hong Kong, Hiroko Tabuchi from Tokyo, Alan Cowell from London, and Thom Shanker from Washington.