If the containment at the nuclear power plant damaged by Japan's devastating earthquake fails, a potential radiation plume from a full core meltdown could reach Tokyo, a U.S. scientists' organization said on Tuesday.
Japan faces a potential catastrophe after a stricken nuclear power plant exploded and sent low levels of radiation floating toward Tokyo, prompting some people to flee the capital and others to stock up on essential supplies.
The Union of Concerned Scientists also said a "jerry-rigged" cooling system at the Japanese plant would be hard to maintain if all workers there were evacuated.
Nuclear power and safety experts at the group said they were "very concerned" that ongoing activities at the plant would become more challenging for on-site workers. A larger radiation plume could travel hundreds of miles (km), the scientists said in a telephone briefing.
A crack in the containment vessel could allow radiation to exit the reactor in case of a core meltdown, the scientists said. They said the Japanese government should extend the evacuation zone around the troubled Fukushima Daiichi power station.
TOKYO - The operator of Japan's stricken Fukushima Dai-Ichi nuclear power plant says it has scrapped a plan to use helicopters to pour water into a reactor whose overheating fuel storage unit was emitting radiation.
The storage pool, used to hold spent nuclear fuel rods, caught fire Tuesday in an alarming escalation of Japan's nuclear crisis. The blaze was extinguished but fears remain that water may boil away and the rods could be dangerously exposed.
Tokyo Electric Power Co. spokesman Hajimi Motojuku said early Wednesday that helicopters were deemed impractical, but that other options were under consideration, including fire engines.
Officials are struggling to address the failure of safety systems at several of the plant's reactors after Friday's massive earthquake and tsunami. (The Associated Press)
TOKYO - Japan's nuclear agency raises severity rating of nuclear accident from 4 to 5 on 7-level scale.