Radioactive Plume From Japan Expected To Hit Mainland U.S. Friday

The Japanese nuclear crisis is becoming an international issue:

A United Nations forecast of the possible movement of the radioactive plume coming from crippled Japanese reactors shows it churning across the Pacific, and touching the Aleutian Islands on Thursday before hitting Southern California late Friday.

Health and nuclear experts emphasize that radiation in the plume will be diluted as it travels and, at worst, would have extremely minor health consequences in the United States, even if hints of it are ultimately detectable. In a similar way, radiation from the Chernobyl disaster in 1986 spread around the globe and reached the West Coast of the United States in 10 days, its levels measurable but minuscule.

The projection, by the Comprehensive Test Ban Treaty Organization, an arm of the United Nations in Vienna, gives no information about actual radiation levels but only shows how a radioactive plume would probably move and disperse.

The forecast, calculated Tuesday, is based on patterns of Pacific winds at that time and the predicted path is likely to change as weather patterns shift.

On Sunday, the United States Nuclear Regulatory Commission said it expected that no “harmful levels of radioactivity” would travel from Japan to the United States “given the thousands of miles between the two countries.”

The test ban treaty group routinely does radiation projections in an effort to understand which of its global stations to activate for monitoring the worldwide ban on nuclear arms testing. It has more than 60 stations that sniff the air for radiation spikes and uses weather forecasts and powerful computers to model the transport of radiation on the winds.

On Wednesday, the agency declined to release its Japanese forecast, which The New York Times obtained from other sources. The forecast was distributed widely to the agency’s member states.

But in interviews, the technical specialists of the agency did address how and why the forecast had been drawn up.

“It’s simply an indication,” said Lassina Zerbo, head of the agency’s International Data Center. “We have global coverage. So when something happens, it’s important for us to know which station can pick up the event.”

For instance, the Japan forecast shows that the radioactive plume will probably miss the agency’s monitoring stations at Midway and in the Hawaiian Islands but is likely to be detected in the Aleutians and at a monitoring station in Sacramento.

The forecast assumes that radioactivity in Japan is released continuously and forms a rising plume. It ends with the plume heading into Southern California and the American Southwest, including Nevada, Utah and Arizona. The plume would have continued eastward if the United Nations scientists had run the projection forward.

Clearly nothing to panic over, but this is still likely to increase pressure on the Japanese government.

FILED UNDER: Asia, Natural Disasters, World Politics, , , , , , , , ,
Doug Mataconis
About Doug Mataconis
Doug Mataconis held a B.A. in Political Science from Rutgers University and J.D. from George Mason University School of Law. He joined the staff of OTB in May 2010 and contributed a staggering 16,483 posts before his retirement in January 2020. He passed far too young in July 2021.


  1. john personna says:

    I hope to catch a non-radioactive trout today, before it happens … though I suppose giant, radioactive, mutant, trout would me more of a challenge.

    (My heart goes out the the Japanese, who face the real problem(s))

  2. JKB says:

    Well, this certainly goes to show that no crisis will be let go to waste. They’ve barely had high radiation readings at the perimeter fence of the plant and now we get this.

    Yes, wind currents flow across the Pacific. Yes, that will carry radiated particles. But guess what, few have been released and there will be lots of time for decay of the short lived particles. I notice they don’t mention that there was no great die-off in Europe due to Chernobyl even though it spewed tons of actual core into the atmosphere, not a bit of steam and hydrogen.

    We’re going to see a lot of gnashing of teeth and rending of clothes over this by the very same people who eagerly jump on a plane to ski in Colorado, where background radiation is higher.

  3. Steven Plunk says:

    The media hyperventilates while it compares this the Chernobyl. Experts not on TV explain how it is nothing like Chernobyl even in the worst case.

    The bigger problem is how this distracts from the real disaster and relief efforts. Cleaning up after a tsunami isn’t cool the way a meltdown is. I’m hating the media more every day.

  4. Franklin says:

    They’ve barely had high radiation readings at the perimeter fence of the plant and now we get this.

    Getting a year’s worth of radiation in a few minutes is just “barely high”? I guess I don’t agree with your subjective assessment.

  5. john personna says:

    JKB, don’t forget people who lean on their granite counter tops, as they worry about radiation.

  6. john personna says:

    (BTW, I wouldn’t worry about this being a “real issue” or even a “distraction.” It’s off the radar to people dealing with real and immediate problems (in Japan))

  7. anjin-san says:

    > The bigger problem is how this distracts from the real disaster and relief efforts.

    Really WTF are you talking about? How exactly does what a cable news talking head says in America “distract from the relief effort”? That work is being done in Japan, they don’t really give a rat’s ass what is on American TV, especially right now. Everyone who is interested in being informed knows about the scope of the disaster, and they certainly can find out about relief efforts with a few mouse clicks. People who are more interested in reality TV will stay that way.

    Let me translate your comments from tea party babble to English. “The ‘enviro-wackos’ were right about the dangers of nuclear power, just like they were right about the dangers of offshore drilling. But they can’t talk about it because we say so.