Gracious

Zentralanstalt für Meteorologie und Geodynamik. A-1190 Wien,

First emission estimates

Regarding Iodine-131, the picture is relatively homogeneous. A source term of
1017 Bq per day would explain the measurements in Takasaki as well as Sacramento.
The total 4-day emission of 4 1017 Bq is on the order of 20% of the total emissions of
Iodine-131 that occurred during the Chernobyl accident. Regarding Cesium-137, the
situation is a bit different. In the cloud eventually propagating to the United States, the
ratio of Iodine-131 to Cesium-137 was about 30. This is similar to the Chernobyl
accident. In Takasaki, however, this ratio was four. This would indicate a much larger
Cesium-137 release in the second two-day period after the accident. Taking this
together, the source terms would be about 3 1015 Bq during the first two days, and 3
1016 during the second two-day period. In sum, this could amount to about 50% of
the Chernobyl source term of Cesium-137.
http://www.zamg.ac.at/docs/aktuell/Japan2011-03-22_1500_E.pdf