15.1 Introduction
15.2 Method
15.2.1 Reverse Estimation Method
15.2.2 Environmental Monitoring Data
15.2.3 Atmospheric Dispersion Simulation
15.2.4 Reconstruction of Local Atmospheric Dispersion Process
15.2.5 Radionuclides
15.3 Results and Discussion
15.3.1 Preliminary Source Term Estimation
15.3.2 Detailed Analysis on the Local Atmospheric Dispersion Process
15.3.3 Reestimation of Source Term for the Early Phase of the Accident
15.3.4 Validation of Source Term by the Regional-Scale Atmospheric Dispersion Simulation
No. | Start time (JST) | Duration (h) |
131I (Bq h−1) |
137Cs (Bq h−1) |
131I/137Cs | Height (m) |
---|---|---|---|---|---|---|
1 | 2011/3/12 05:00 | 4.5 | 3.7E + 13 | 3.7E + 12 | 10 | 20 |
2 | 2011/3/12 09:30 | 6.0 | 1.7E + 13 | 1.7E + 12 | 10 | 120 |
3 | 2011/3/12 15:30 | 0.5 | 3.0E + 15 | 3.0E + 14 | 10 | 100 (volume) |
4 | 2011/3/12 16:00 | 31.0 | 8.4E + 13 | 8.4E + 12 | 10 | 120 |
5 | 2011/3/13 23:00 | 12.0 | 3.6E + 13 | 3.6E + 12 | 10 | 120 |
6 | 2011/3/14 11:00 | 0.5 | 3.0E + 15 | 3.0E + 14 | 10 | 300 (volume) |
7 | 2011/3/14 11:30 | 10.0 | 2.3E + 13 | 2.3E + 12 | 10 | 20 |
8 | 2011/3/14 21:30 | 2.5 | 1.3E + 15 | 1.3E + 14 | 10 | 120 |
9 | 2011/3/15 00:00 | 7.0 | 3.5E + 14 | 4.0E + 13 | 8.8 | 120 |
10 | 2011/3/15 07:00 | 3.0 | 3.0E + 15 | 3.0E + 14 | 10 | 20 |
11 | 2011/3/15 10:00 | 3.0 | 8.0E + 13 | 8.0E + 12 | 10 | 20 |
12 | 2011/3/15 13:00 | 4.0 | 4.0E + 15 | 4.0E + 14 | 10 | 20 |
13 | 2011/3/15 17:00 | 37.0 | 2.1E + 14 | 3.0E + 12 | 70 | 20 |
14 | 2011/3/17 06:00 | 57.0 | 4.1E + 14 | 1.0E + 13 | 41 | 20 |
15 | 2011/3/19 15:00 | 36.0 | 3.8E + 14 | 3.5E + 13 | 11 | 20 |
16 | 2011/3/21 03:00 | 18.0 | 1.4E + 14 | 1.4E + 13 | 10 | 20 |
17 | 2011/3/21 21:00 | 26.0 | 4.1E + 14 | 4.7E + 12 | 87 | 20 |
18 | 2011/3/22 23:00 | 25.0 | 7.1E + 14 | 8.9E + 12 | 80 | 20 |
19 | 2011/3/24 00:00 | 24.0 | 1.9E + 14 | 2.9E + 12 | 66 | 20 |
20 | 2011/3/25 00:00 | 35.0 | 5.6E + 13 | 1.2E + 12 | 45 | 20 |
21 | 2011/3/26 11:00 | 47.0 | 4.0E + 12 | 1.7E + 11 | 23 | 20 |
22 | 2011/3/28 10:00 | 35.0 | 7.5E + 12 | 4.7E + 12 | 1.6 | 20 |
23 | 2011/3/29 21:00 | 14.0 | 1.5E + 13 | 8.8E + 12 | 1.7 | 20 |
24 | 2011/3/30 11:00 | 13.0 | 1.8E + 14 | 1.4E + 14 | 1.3 | 20 |
25 | 2011/3/31 00:00 | 22.0 | 2.4E + 13 | 4.5E + 12 | 5.3 | 20 |
26 | 2011/3/31 22:00 | 35.0 | 1.8E + 12 | 1.6E + 12 | 1.1 | 20 |
27 | 2011/4/02 09:00 | 48.0 | 1.8E + 12 | 5.8E + 11 | 3.1 | 20 |
28 | 2011/4/04 09:00 | 80.0 | 7.0E + 11 | 1.4E + 11 | 4.9 | 20 |
29 | 2011/4/07 17:00 | 150.0 | 7.0E + 11 | 3.5E + 11 | 2.0 | 20 |
30 | 2011/4/13 23:00 | 409.0 | 7.0E + 11 | 1.8E + 11 | 4.0 | 20 |
Radionuclides | FA2 (%) | FA5 (%) | FA10 (%) | Correlation coefficients |
---|---|---|---|---|
131I | 22.4 | 48.7 | 65.8 | 0.75 |
137Cs | 26.5 | 48.5 | 70.6 | 0.72 |
15.3.5 Formation Processes of 137Cs Deposition over Eastern Japan
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Dry deposition in the northeastern coastal area of Miyagi Prefecture on 12 March
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Wet and dry deposition in Fukushima Prefecture and the north of Tochigi and Gunma Prefectures on 15 March
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Dry deposition in the north of Ibaraki Prefecture on 15 March and, possibly, dry and wet deposition on 16 March
-
Wet deposition in the area from the south of Iwate Prefecture to the northwest of Miyagi Prefecture on 20 March
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Wet deposition in the Kanto region, especially in the area from the south of Ibaraki Prefecture to the northwest of Chiba Prefecture, from 21 to 23 March