Study: Global consequences from Fukushima-like nuclear disaster; Many nations at risk of ‘great exposure’ — Transport of hot particles to US was especially effective during worst releases after reactor explosions — Radioactivity confined ‘close to surface’ due to seasonal factorsT. Christoudias and Y. Proestos of The Cyprus Institute, J. Lelieveld of Max Planck Institute of Chemistry (Germany), Dec 12, 2014 (emphasis added):
- We estimate the contamination risks from the atmospheric dispersion of radionuclides released by severe nuclear power plant accidents… We present an overview of global risks… [These] risks exhibit seasonal variability, with the highest surface level concentrations of gaseous radionuclides in the Northern Hemisphere during winter [Fukushima crisis began with 10 days left in winter].
- The model setup was evaluated… using emission estimates from… Fukushima
- The risk posed from nuclear power plant accidents is not limited to the national or even regional level, but can assume global dimensions. Many nations may be subjected to great exposure after severe accidents.
- Our model shows increased surface-level concentrations throughout the Northern Hemisphere during the boreal winter months compared to the summer… Not only the expected risk magnitude is higher, but the geographical extent of the high concentrations of transported radionuclides is more pronounced towards the north… Horizontal advection [i.e. transfer] is more efficient in winter due to relatively stronger winds, and the concentrations are highest near the surface [and] surface level concentrations in the summer tend to be more localized in the emission region.
- Our results illustrate that accidents… could have significant trans-boundary consequences. The risk estimate [shows] increased surface level concentrations of gaseous radionuclides in the Northern Hemisphere during winter and a larger geographical extent towards the north and the east… This is related to the relatively shallow boundary layer in winter that confines the emitted radioactivity to the lowest part of the atmosphere close to the surface…It is the view of the authors that it is imperative to assess the risks from the atmospheric dispersion of radioactivity from potential NPP accidents [for] emergency response planning on national and international levels.
JAMSTEC, Univ. of Tokyo, etc.: We show a numerical simulation for the long-range transport from the [Fukushima] plant to the US… Large-scale updraft [over] Japan from March 14 to 15 was found effective in lifting the particles [to the] jet stream that could carry the particles across the Pacific within 3 to 4 days [See study: On Mar. 15, Fukushima reactors emitted 100 quadrillion Bq of cesium into air — This one day was equal to total lifetime release from Chernobyl]… Some of the particles [had a] long-range atmospheric transport over — 10,000 km within 3 to 4 days… [R]adioactive materials were detected in that period over the east and west coasts of the U.S… In order for the particles to be transported with the jet stream, they must be lifted up from the surface boundary layer to the mid- or upper troposphere. Large-scale updraft was indeed observed… on March 14 through 15… [T]he westerlies in mid-March were thus particularly effective in the trans-Pacific transport of the radioactive materials…
Watch the numerical plume simulation here http://www.docin.com/p-773002550.html