Trace radioactivity from Japan likely over the Western U.S. today
Traces of radioactive substances emitted by Japan's damaged Fukushima nuclear power plant will likely arrive over the Western U.S. today, carried by the prevailing west to east winds that have blown over the Pacific Ocean during the past week. Rainfall is expected over California this weekend, and it is likely that the rain will wash radioactive particles out of the air to the surface in quantities that will be detectable at several locations. I want to strongly emphasize that the radioactivity from Japan arriving over the U.S. over the next few days poses absolutely no threat to human health, and is present in only miniscule quantities. The radioactive plumes from Japan have had seven days to dilute over a 5000+ mile journey, and have been subject to deposition to the ocean due to gravity and rainfall along the way. Natural radiation is present in our environment every day, and the extra radiation from the Fukushima nuclear plant will cause much less than a 1% increase this background radiation. Radioactive particles from the Chernobyl disaster in 1986 were detected in North America ten days after that event, and caused no harmful effects. The radiation from Japan over U.S. during the next week should be at levels even lower than the Chernobyl fallout.
Figure 1. Backward trajectories for the air arriving at the surface (red line) and 300 meters altitude (blue line) in San Francisco, California on Saturday, March 19, at 11am PDT. According to the latest run of the GFS model, the air arriving in San Franciso tomorrow will have originated near the surface in northern Japan last Saturday, when radioactive emissions from the Fukushima nuclear plant began. The radioactive particles arriving in California will be in trace quantities, and will have no harmful effects on human health. Images created using NOAA's HYSPLIT trajectory model.
Radioactive plumes emitted from Japan's troubled Fukushima nuclear power plant continue to move offshore to the east over the Pacific Ocean today, thanks to predominantly west winds blowing at 5 - 15 mph. These winds are being driven by the clockwise flow of air around a surface high pressure system centered just southeast of Tokyo. As this high pressure system moves northeastwards, parallel to the Japanese coast, today through Saturday, winds will gradually shift to the southwest, keeping the radiation from the Fukushima plant blowing out to sea. As the winds shift to southwesterly, the sinking air over Japan will be replaced by rising air, and radioactive emissions will begin being lifted high in the atmosphere. Since there is less friction aloft, and the high speed winds of jet stream increase as the air moves higher in the atmosphere, this radiation will undergo long-range transport. Latest trajectory runs using NOAA's HYSPLIT model (Figures 2 - 4) show that radioactivity emitted today could wind up over Alaska after five days, and radioactive particles emitted on Saturday could make it to California by late next week. I've made trajectory plots for the next three days assuming two possible release altitudes--a surface-based release near 10 meters, which should be the predominant altitude in the current situation, and a higher release altitude of 300 meters, which might occur if there is an explosion and major fire. However, the 5-day trek to Hawaii and California is 4000 - 5000 miles, and a tremendous amount of dispersion and dilution of the radioactive plume will occur. Given the current levels of radiation being emitted, any radioactivity reaching Hawaii or the U.S. may be difficult to detect, and will not be a threat to human health. Keep in mind also that the most dangerous radionuclide to human health in the radioactive plume--Iodine-131--has a half life of eight days, so will be reduced by at least 30% after 5 days of travel time.
Of much greater concern is the possibility of dangerous level of radiation over Japan. The next period of onshore winds that will blow radioactivity inland over Japan may occur beginning on Saturday night (U.S. time), continuing through Sunday, according to the latest run of the GFS model. The latest HYSPLIT trajectories show winds on Sunday may carry radiation from the disaster site southwards over Tokyo. A low pressure system is expected to bring considerable rain to Japan on Sunday, and this rain is likely to remove most of the radioactivity from the air where rain and radioactivity are both present. The winds associated with this low are difficult to predict at this time, since the winds will be light and variable.
Figure 2. Five-day forecast movement of plumes of radioactive air emitted at 10 meters altitude (red line) and 300 meters (blue line) at 18 UTC (2pm EDT) Friday, March 18, 2011 from the Fukushima Daiichi nuclear plant. The plumes get caught in a southwesterly flow of air in advance of an approaching low pressure system. The plume emitted near the surface (red line) stays trapped near the surface for 4 days then lifted to 4 km, but the plume emitted at 300 meters is lifted to 5 km altitude after 2 1/2 days by the rising air associated with the approaching low pressure system. Images created using NOAA's HYSPLIT trajectory model.
Figure 3. Five-day forecast movement of plumes of radioactive air emitted at 10 meters altitude (red line) and 300 meters (blue line) at 18 UTC (2pm EDT) Saturday, March 19, 2011 from the Fukushima Daiichi nuclear plant. The plumes get caught in a southwesterly flow of air in advance of an approaching low pressure system and lifted to 4 - 5 km altitude. The plumes are predicted to move over California and Mexico at high altitude. Images created using NOAA's HYSPLIT trajectory model.
Figure 4. One-day forecast movement of plumes of radioactive air emitted at 10 meters altitude (red line) and 100 meters (blue line) at 18 UTC (2pm EDT) Sunday, March 20, 2011 from the Fukushima Daiichi nuclear plant. The plumes get caught northerly winds, and the two lower altitude plumes move over Tokyo by 6 UTC on Monday, March 21. This is a low confidence forecast, as winds are expected to be light and somewhat variable on Sunday over Japan. Images created using NOAA's HYSPLIT trajectory model.
Resources
Seven-day weather forecast for Sendai near the Fukushima nuclear plant
The Austrian Weather Service is running trajectory models for Japan.
Current radar loops from the Japan Meteorological Agency
Jeff Masters
Reader Comments
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Its good to remind people that the levels of radiation have been diluted and pose not threat to human health!
Thank you for a great blog.
HYSPLIT readings set at 0,100,1000 meter start elevations
Is it possible for you to get a link to it or permission to host it? I haven't been able to source it.
Link
In radioactive fallout, plutonium is the least of your concerns. There are other materials far more radioactive and absorbed by the body much more easily.
M
MOx fuel is confirmed as fuel in Reactor No. 3 – Norway Bellona
By nuclearhistory
fourth source confirming MOx.
Japan government not describing particulate nature of reactor emissions. Experts treating particles as external transient hazards; Not explaining consequences of inhalation and continual internal doses. Particles are fundamentally outside of body, a major risk inside body. How big a hazard depends on actual substanes taken in. The rate of radioacitivity of the hundreds of different substances varies very widely. The isotopes of alpha emitting substances must be confirmed to determine consequences.
Pu-239 has a half-life of ~24200 years, so it will not be reduced in the plume by fission anytime soon. The fact that it is an intense alpha emitter makes it extremely dangerous if even a tiny particle is inhaled. Just because it is a "heavy" element does not mean that small particles of plutonium cannot be lofted into the plume, that is absurd. Do you even have the slightest background in atmospheric aerosol and particle physics? Do you have any sources to back your claims?
A study of the former open-air French nuclear bomb test site in Algeria found that Pu-239 was present and significantly dispersed. Read for yourself:
Radiological Conditions at the Former French
Nuclear Test Sites in Algeria: Preliminary Assessment
and Recommendations (pdf)
When a banana is eaten, a person's "dose equivalent is about 0.01 mrem which is equivalent to 0.1 μSv". Apparently the amount coming to the US from Japan per day will give a per-person dose well under the BED. And it takes 1,000 BED to increase "an average adult human's risk of death by about one micromort – the same risk as .......smoking 1.4 cigarettes"
Doc, you must be very proud and impressed that so may highly educated and knowledgeable experts take the time from their busy lives to comment on this blog.
Truly astounding.
Both nuclear bombs and nuclear power generation involve nuclear fission, so there are really more similarities than differences. Just the fact that low levels of enhanced radiation are reaching the USA should be enough to alert you to the fallacies in your argument. True, the increased radiation levels pose no threat, but ingestion of certain dangerous radionuclides can pose a danger. Those with long half-lives will continue to pose a danger as they become part of our food chain.
In the case of Pu-239, inhalation is the primary danger, but larger doses become incorporated in human bone and liver. We will not see those larger amounts, but even one inhaled particle is life-threatening.
Not in 4 days now.
Japan NHK TV English USTREAM Live feed
you forget the E in note in for days from now it i think
True, you may not contract the cancer for many years, but when you do it will become the greatest of your concerns.
Japanese authorities have informed the IAEA that, prior to the earthquake of 12 March, the entire fuel core of reactor Unit 4 of the Fukushima Daiichi nuclear power plant had been unloaded from the reactor and placed in the spent fuel pond located in the reactor's building.
"LaL"
While I won't comment on the aerosol dispersal, I will comment on the alpha radiation.
Alpha emission are the WEAKEST level of ionizing radiation. Radioactive cesium, strontium, and iodine are BETA and GAMMA emitters. They are also MUCH more radioactive, as are most other high-energy fission by-products. Radioactive cesium 137, for example, which is released in much higher quantities has a half-life of just over 30 years (roughly the same as strontium 90).
The incidents of radiation sickness at Bikini were not induced by plutonium. it was induced by cesium. Iodine 131 is even more radioactive and due to the way it decays can cause massive cellular damage. The saving grace here is that it has a short half-life of 8 days.
Link
If its simple, why don't you go for a degree in it then?
I once had someone tell me "oh meteorology, its not that bad, thunderstorms are pretty easy to understand".
Then I asked him: well why don't you try and go for a degree since you think its so easy?
He said "well I uh, I'm not very good at math, and physics is really hard."
:)
Alpha emitters are extremely dangerous if they become incorporated into your body. Radium-226 is a strong alpha emitter with a half-life of ~1600 years. I think we all have heard the stories of the radium watch painters and their gruesome fate, and we also know what caused the death of Marie Curie.
Thanks for chiming in. Your post really contributed greatly to the discussion. Sarcasm meter on high.
RIP George Carlin! We miss you dearly! A pure comic genius...
If what you say is true, how is it that so many on here disagree with each other. Does that mean that one of them is right and all the others are wrong? Or does it mean that none of them know what they are talking about?
Please inform me. I am confused. If it is so easy, they should all be in agreement.
Just not politically...
When you get a degree in meteorology, it is like having an engineering, physics, or geophysics degree.
At A&M we took 3-4 physics classes, calculus 1-3, differential equations, numerical methods and linear algebra...plus the core dynamics/thermodynamics courses for meteorology.
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