SOMA, Japan: Water levels dropped precipitously Monday inside a Japanese nuclear reactor, twice leaving the uranium fuel rods completely exposed and raising the threat of a meltdown, hours after a hydrogen explosion tore through the building housing a different reactor. Water levels were restored after the first decrease, but the rods remained partially exposed late Monday night, increasing the risk of the spread of radiation and the potential for an eventual meltdown. The cascading troubles in the Fukushima Dai-ichi plant compounded the immense challenges faced by the Tokyo government, already struggling to send relief to hundreds of thousands of people along the country's quake- and tsunami-ravaged coast where at least 10,000 people are believed to have died. Later, a top Japanese official said the fuel rods in all three of the most troubled nuclear reactors appeared to be melting. Of all these troubles, the drop in water levels at Unit 2 had officials the most worried. “Units 1 and 3 are at least somewhat stabilized for the time being,” said Nuclear and Industrial Agency official Ryohei Shiomi. “Unit 2 now requires all our effort and attention.” Workers managed to raise water levels after the second drop Monday night, but they began falling for a third time, according to nuclear agency official Naoki Kumagai. They are now considering spraying water directly on container to cool it. The head of the International Atomic Energy Agency said the Japanese goverment has asked the agency to send experts to help. In some ways, the explosion at Unit 3 was not as dire as it might seem. The blast actually lessened pressure building inside the troubled reactor, and officials said the all-important containment shell — thick concrete armor around the reactor — had not been damaged. In addition, officials said radiation levels remained within legal limits, though anyone left within 20 kilometers of the scene was ordered to remain indoors. “We have no evidence of harmful radiation exposure,” deputy Cabinet secretary Noriyuki Shikata told reporters. Fukushima prefectural officials said, however, that 190 people have been exposed to some radiation from the plant. Nuclear safety officials said monitoring devices around the plant briefly showed radiation levels six times the legal limit, but they have since gone down. Japan faces a recovery and reconstruction bill of at least $180 billion, or 3 percent of its annual economic output, analysts said. Even though some extreme projections of the longer-term costs project figures closer to $1 trillion over several years, standard tallies akin to those used after the Kobe quake hover around this level. Late Monday, the chief government spokesman said there were signs that the fuel rods were melting in all three reactors, all of which had lost their cooling systems in the wake of Friday's massive earthquake and tsunami. “Although we cannot directly check it, it's highly likely happening,” Chief Cabinet Secretary Yukio Edano told reporters. Some experts would consider that a partial meltdown. Others, though, reserve that term for times when nuclear fuel melts through a reactor's innermost chamber but not through the outer containment shell. Officials held out the possibility that, too, may be happening. The Monday morning explosion at the Fukushima Dai-ichi plant's Unit 3 injured 11 workers and came as authorities were trying to use seawater to cool the complex's three reactors. Meanwhile, 17 US military personnel involved in helicopter relief missions were found to have been exposed to low levels of radiation after they flew back from the devastated coast to the USS Ronald Reagan, an aircraft carrier about 160 kilometers offshore. US officials said the exposure level was roughly equal to one month's normal exposure to natural background radiation, and the 17 were declared contamination-free after scrubbing with soap and water. As a precaution, the US said the carrier and other 7th Fleet ships involved in relief efforts had shifted to another area. Overall, more than 1,500 people had been scanned for radiation exposure in the area, officials said.
