Japan embarked on a desperate series of initiatives to regain control as conditions at its failing nuclear plant deteriorated further on Wednesday. It called in helicopters, water cannon and even, reportedly, a US spy plane.
But the work was hampered by radiation levels that forced technicians to briefly suspend operations. They took shelter as the radiation level spiked at the site in the morning and only returned when the government more than doubled the safety limit determining the maximum legal dose of radiation for workers.
In a rare television appearance to express his sympathy for the victims of the earthquake and tsunami, Emperor Akihito voiced deep concern about the "unpredictable" situation at Fukushima.
There was also concern that the nuclear crisis had hampered relief efforts aimed at residents of the area. The government's chief spokesman, Yukio Edano, said he had heard food and supplies were not being delivered to areas outside the evacuation zones and urged people not to overreact so that relief would get to survivors.
Officials appear to have lost all faith in ability of the plant's operators, the Tokyo Electric Power Company, to handle the crisis.
A Japanese government source told Kyodo news agency that a US spy plane would fly over the facility on Thursday, in the hope that its infrared cameras could provide clues as to what was happening inside the reactor buildings.
Earlier, Naoto Kan, the prime minister, ordered officials to measure radiation levels across Japan and supply information to the public, with details on safe and unsafe levels.
The broadcaster NHK aired what at first appeared to be a weather forecast – with a suited presenter gesturing at the map behind her – but was in fact a guide to radiation readings across northeast Japan and Tokyo.
But while radiation levels in the capital have been higher than usual, hitting 10 times the normal levels at one point, they remained low judged by safety standards, as of Wednesday evening.
Although the US and UK were urging their nationals to move further from the region – less than 24 hours after assuring them that the Japanese measures were appropriate – the real threat was that facing workers at the plant.
Tepco evacuated hundreds of workers on Tuesday following a surge in radiation, leaving only a core team of 50 to 70 people, although some reports suggested more staff may have returned to the facility on Wednesday.
The first problems with the plant became evident shortly after the quake and tsunami, when it emerged that the cooling systems were failing to work.
Workers continue to pump seawater into the first three reactors, the initial cause of concern, in an attempt to contain the situation. Unit 1 is known to have experienced partial melting of the core and it is feared the others have too. That is particularly worrying in unit 2, which suffered damage to its containment vessel. The outer buildings of all three have been damaged by hydrogen explosions.
Attention is increasingly focusing on the threat posed by spent fuel rods, with signs of problems in storage pools at four of the units.
Experts say if the rods are exposed to the air their zirconium alloy coating could react and release radiation. Unlike the reactors, the pools are not contained – meaning that if they release radioactive material there is only the building to prevent it leaking further into the environment. In at least two of the affected units, that outer casing has been damaged.
The new danger emerged on Tuesday in unit 4 – under maintenance at the time of the tsunami – with news of a blaze and reports that water levels in the storage pool might be dropping. On Wednesday it suffered a second fire and smoke or steam began to emerge.
With the mood becoming increasingly desperate, officials contemplated a range of measures. At first they said Japanese forces would spray water over unit 3's spent fuel pool and helicopters were seen taking to the air with buckets of seawater. But they landed again without approaching the reactors when experts judged the radiation risk to the pilots unacceptably high.
The plan was fraught with difficulties in any case. "My estimates suggest they might need 50 tonnes an hour of water. You could do that easily with a large-bore hosepipe but if you are doing it with helicopters it is a lot more difficult," said Professor David Hinde, head of nuclear physics at the Australian National University.
A water cannon was brought into use at unit 4. It was not clear how officials planned to deal with unit 3.
The battle to control the plant gets harder as it goes on, not only because of the multiplying problems but because workers are increasingly tired and will have to be pulled out as they hit exposure limits.
"The longer it goes on, the more people are going to be on the bench," said Hinde.