Radiation exposure: How big is the threat in Japan?

On Sunday, Fukushima reactor 3 was vented again at which point there is believed to have been a partial meltdown in the reactor. A company spokesman stated that the radiation released thus far did not pose a health risk to humans. Later that day the cooling system in reactor 2 failed, and more radioactive steam was control-released.

The concern is that that radioactive steam will eventually fall back to earth and contaminate food and water supplies.

On Monday, reactor 3 experienced a hydrogen explosion that blew the roof off its containment building. On Tuesday, a fire broke out at the fourth reactor and there were reports that the storage pond, holding spent fuel rods, had boiled over. The fire was extinguished, but Chief Cabinet Secretary Yukio Edano said that more radiation was released as a result and that "now we are talking about levels that can damage human health."

Edano went on to warn, "Please do not go outside. Please stay indoors. Please close windows and make your homes airtight. Don't turn on ventilators. Please hang your laundry indoors."

With radiation close to the reactors measuring four times higher than the maximum allowable limit of 100,000 microsieverts per hour, according to the International Atomic Energy Agency, residents are asking: How dangerous it is around Fukushima?

RADIATION DANGERS

As of Monday, the plant was emitting as much radiation in one hour as it normally would in six months, but government spokesman, Yukio Edano, said "The possibility that a large amount of radiation has been released is low."

Matthew Bunn, co-principal investigator of the Managing the Atom Project at Harvard’s Belfer Center for Science and International Affairs noted that one risk is the release of "a very modest amount of cesium and other fission products" from partial meltdowns, such as those we have seen in reactor 1 and 3. Mr. Bunn went on to say another possibility is a complete nuclear meltdown. If the fuel in the reactors overheats and melts through the bottom of the steel containment vessel, it may reach an underground water source and create much more dangerous radioactive steam.

One of the spent-fuel pools where the used radioactive rods are normally cooled has already released steam. The condition of the pools and their cooling systems after the hydrogen explosions are unknown and experts say that if the pools have been compromised, they could release more radiation than a reactor meltdown. The pools have far more radioactivity than the reactors, and do not have the protection of a containment building. Arjun Makhijani, a nuclear engineer and president of the anti-nuclear power Institute for Energy and Environmental Research, says "damaged reactors are less likely to spread the same vast amounts of radiation that Chernobyl did, but a spent-fuel pool fire could very well produce damage similar to or even greater than Chernobyl."

Previous

1 | 2 | 3

Next