KORIYAMA, Japan — Japan's nuclear crisis intensified Sunday as authorities raced to combat the threat of multiple reactor meltdowns and more than 170,000 people evacuated the quake- and tsunami-savaged northeastern coast where fears spread over possible radioactive contamination.
Nuclear plant operators were frantically trying to keep temperatures down in a series of nuclear reactors — including one where officials feared a partial meltdown could be happening Sunday — to prevent the disaster from growing worse.
Chief Cabinet Secretary Yukio Edano also said Sunday that a hydrogen explosion could occur at Unit 3 of the Fukushima Dai-ichi nuclear complex, the latest reactor to face a possible meltdown. That follows a blast the day before in the power plant's Unit 1, as operators attempted to prevent a meltdown there by injecting sea water into it.
"At the risk of raising further public concern, we cannot rule out the possibility of an explosion," Edano said. "If there is an explosion, however, there would be no significant impact on human health."
More than 170,000 people had been evacuated as a precaution, though Edano said the radioactivity released into the environment so far was so small it didn't pose any health threats.
"First I was worried about the quake," Kenji Koshiba, a construction worker who lives near the plant. "Now I'm worried about radiation." He spoke at an emergency center in Koriyama town near the power plant in Fukushima.
Edano said neither Fukushima Dai-ichi reactor was near the point of complete meltdown, and he was confident of escaping the worst scenarios.
A complete meltdown — the collapse of a power plant's systems and its ability to keep temperatures under control — could release uranium and dangerous contaminants into the environment and pose major, widespread health risks.
Up to 160 people, including 60 elderly patients and medical staff who had been waiting for evacuation in the nearby town of Futabe, and 100 others evacuating by bus, might have been exposed to radiation, said Ryo Miyake, a spokesman from Japan's nuclear agency. The severity of their exposure, or if it had reached dangerous levels, was not clear. They were being taken to hospitals.