The radiation level at the Fukushima No. 1 nuclear power plant, which was hit by the earthquake, has exceeded the legal limit, posing extreme danger to the people in a multi-kilometer radius and spawning long-term environmental hazards.

Even as radiation from the No. 1 reactor went above the legal limit of 500 to hit 882 on Sunday, the cooling system at the No.3 reactor has failed; a development that can potentially lead to the failure of the reactor.

The Tokyo Electric Power Co., which runs the Fukushima atomic power plant, notified the government early Sunday morning of a potentially dangerous development of the reactor core of the No.3 plant loosing its cooling ability. When the cooling function at the fuel core fails, it leads to extreme heating of the core, leading to a blast or dangerous levels of radiation.

It was the sixth reactor overall at the Fukushima No. 1 and No. 2 plants to undergo cooling failure since the massive earthquake and ensuing tsunami struck Japan on Friday, Kyodo News reported.

A nuclear reactor failure is not as catastrophic like an atom bomb as it doesn't cause a gigantic flare-up emitting immeasurable amounts of heat and radiation. A blast at the reactor core causes the spread of radioactive substances through air, which contaminates people and environment.

However, the specter of a Chernobyl-like disaster loomed after reports said more than a dozen people were contaminated by radioactive substances and thousands fled the area.