Radiation from Japan. What it means.

This is the most balanced and intelligent thing I've read about it so far:

Japanese plant poses little threat to US — for now

[...] Many experts agreed that radiation would likely dissipate and pose far less danger to people farther away, especially those in other countries.

For one, radioactive cesium and iodine can combine with the salt in sea water to become sodium iodide and cesium chloride, which are common elements that would readily dilute in the wide expanse of the Pacific, according to Steven Reese, director of the Radiation Center at Oregon State.

Winds in the area are currently blowing toward the coast because of a winter storm. But that will change to a brisk wind blowing out to sea at least through Wednesday, he said.

[...]

Even so, many experts here say that this emergency is still nowhere near the level of Chernobyl, the worst nuclear disaster in history.

For one, that reactor's core contained graphite that caught fire, which blasted radiation high into the air and into wind currents that carried it long distances. The Japanese core is metal and contains no graphite, experts said.

The Chernobyl plant also lacked a heavy shell around the reactor core. And the incident there happened quickly, with little time to warn nearby residents.

So far, the radiation released in Japan has not reached high altitudes, said Kathryn Higley, director of the Oregon State University Department of Nuclear Engineering and Radiation Health Physics.

"In addition, radioactive material is sticky. It has a static charge," she said, so it will stick to the sides of buildings, and "rain is going to knock it down."

As a precaution, the World Meteorological Organization has activated specialized weather centers to monitor the situation. Those centers, in Beijing, Tokyo and Obninsk, Russia, will track any contaminants.

Japanese officals said that, early Wednesday, the level of radiation at the plant surged to 1,000 millisieverts before coming down to 800 to 600 millisieverts. Still, that was far more than the average.

Doctors say radiation sickness sets in at 1,000 millisieverts and includes nausea and vomiting.

Damage to blood cells can show up two to four weeks later, said Dr. Fred Mettler, a University of New Mexico radiologist and adviser to the United Nations on radiation safety. He led an international study of health effects after the Chernobyl disaster.

Levels are still likely to be lower away from the plant, said Kelly Classic, a radiation physicist at the Mayo Clinic and a representative for the Health Physics Society, an organization of radiation safety specialists.

The U.S. Nuclear Regulatory Commission says doses of less than 100 millisieverts, or 10 rems, over a year are not a health concern.

By comparison, most people receive about three-tenths of a rem every year from natural background radiation, according the U.S. Environmental Protection Agency. A chest X-ray delivers about .1 millisieverts, or .01 rem of radiation; a CT scan of the abdomen and pelvis is about 14 millisieverts, or 1.4 rems.

If a full meltdown occurs at the Japanese plant, the health risks become much greater — with potential release of uranium and plutonium, said Dan Sprau, an environmental health professor and radiation safety expert at East Carolina University in Greenville, N.C.

"If that escapes," Sprau said, "you've got a whole new ball game there."

That's the big question; will it get worse, and if so, by how much?


Also see: Putting a radiation rumor to rest