These simulations are based on publicly available data and original assumptions. Audience should be aware that accuracy of calculation is limited. We would appreciate audience matter-of-factly comprehend our results. We frequently update the calculation whenever additional information is obtained.
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|Ground level air concentration [Bq/m3]|
|Models||Meteorological model：RAMS, Particle transport model：HYPACT||ATMET|
|Period||March 12th, 2011 - April 7th, 2011|
|Range||600 km x 600 km with Fukushima Daiichi Nuclear Power Plant in its center|
|Horizontal lattice||Grid1：600×600[km]、10km mesh|
|Vertical lattice||σ-z coordinate system, Grid with 20km altitude divided into 30 layers|
|Radioactive material released||Iodine - 131|
|Release rate[Bq/s]||Assumption based on released amount estimated by Nuclear Safety Commission*1|
|Release height||Normal：30m, Explosion：30m-200m||Based on press release|
|Decay process||Radioactive decay, dry deposition and wet deposition by precipitation|
|Dry deposition velocity||0.01m/s|
|Washout parameter α||1.2×10-4|
|Washout parameter β||0.8|
|Number of released particles||ca. 20 million particles|
|Meteorological data||MSM (Meso Scale Model) isobaric surface data and AMeDAS precipitation*2||Japan Meteorological Agency|
|Topography data||50m mesh numerical map||Geospatial Information Authority of Japan|
*1 At this point of time, accurate release amount is still unknown. We estimated the release ratio by multiplying coefficient and dose rate at main gate of the facility.(Fig.2)
*2 Precipitation map made from AMeDAS data was derived and applied because precipitation data produced by a meteorological model was not sufficient.
(C)2011 Visible Information Center, Inc.