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Thursday, 21 August 2014

New study finds radiation dose for US West Coast from Fukushima over 500% of recent gov’t estimate

New study finds radiation dose for US West Coast from Fukushima over 500% of recent gov’t estimate — Release from Japan disaster could exceed Chernobyl 

Atmospheric transport and deposition of radionuclides released after the Fukushima Dai-chi accident and resulting effective dose, Atmospheric Environment, Sept. 2014 (emphasis added): On 11 March 2011 an earthquake off the Pacific coast of the Fukushima prefecture generated a tsunami that hit Fukushima Dai-ichi and Fukushima Da-ini Nuclear Power Plants. From 12 March a significant amount of radioactive material was released into the atmosphere and dispersed worldwide. [...] The simulation shows that the radioactive plume, consisting of about 200 PBq by adding contributions from 131I, 134Cs, and 137Cs, has been transported over the entire northern hemisphere [...] An early quantitative estimation of the amount of radioactive material discharged in the atmosphere has been provided by Chino et al. (2011) by coupling environmental monitoring data with atmospheric dispersion simulations, then updated by Katata et al. (2012) with a more detailed description of the emission from the morning of 12 March to late night of 14 March. The total amount of radioactivity has been estimated in 12.6 PBq of 134Cs and 137Cs, and 128.2 PBq of 1311. [...] The uncertainty associated with this source term has been estimated by Chino et al. (2011) to be a factor of 5 or greater.
  • As the study notes “uncertainty associated with this source term has been estimated… to be a factor of 5 or greater.” Using only a factor of 5, the result is 63 PBq of 137Cs (5 x 12.6) and 63 PBq of 134Cs (5 x 12.6) released at Fukushima126 PBq total.
  • According to an estimate by the National Academy published in 1995, “35 PBq of Cs-134 and 70 PBq of Cs-137 were released” at Chernobyl — 105 PBq total.
More from Atmospheric transport and deposition of radionuclides released after the Fukushima Dai-chi accident and resulting effective dose, Sept. 2014: Results at the global scale for the total cumulative effective dose and the three different pathways considered are illustrated in Fig. 7 [an excerpt of this is shown here on the right] […] Cumulative dose in North America reached the maximum value of 27 uSv [microsieverts] on the United States west coast with an average value of about 2 uSv over United States, Canada, and Mexico. The average effective dose in Europe results in 0.17 uSv with the highest value of about 1.5 uSv occurring in the Norwegian west coast Countries experiencing effective doses above the average value arc Spain, France, Finland, and the western Russian regions.
  • Dr. Ken Buesseler, Woods Hole Oceanographic Institute, June 2014: Recently specific numbers from the California Coastal Commission were released in April. What they were doing was taking the peak value in the air in San Francisco and in the water and calculating doses, if someone were to be exposed for an entire year… they came up with a dose of 5 uSv… Not to trivialize and say it’s low… but it’s much higher [in Japan].
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