Preliminary estimation of release amounts of I and Cs accidentally discharged from the Fukushima Daiichi Nuclear Power Plant into the atmosphere

Chino, Masamichi; Nakayama, Hiromasa   ; Nagai, Haruyasu  ; Terada, Hiroaki   ; Katata, Genki; Yamazawa, Hiromi*

The release amounts of I and Cs into the atmosphere due to the Fukushima Daiichi Nuclear Power Plant is preliminary estimated by coupling monitoring data on air concentrations and atmospheric dispersion simulation assuming unit release rate (1 Bq/h). The estimated results show that the large amount of release, the peak value of about 10 Bq/h of I on March 15, continued for a week after the accident, and, after March 23, the release rates have generally been declining to the order of 10 to 10 Bq/h. The total amounts of I and Cs discharged into the atmosphere are estimated about 1.510 Bq and 1.210 Bq.