Bryan Bednarz, Ph.D.
Assistant Professor
Department of Medical Physics
University of Wisconsin - Madison
Half-life
Distribution of Fission Products Released
12% 15%
6%
14%
13%
13%
14%
13%
Cesium-134
2 years
Iodine-135/
Xenon-135
Zirconium-93
7 hours
Cesium-137
30 years
Molybdenum-99/
Technetium-99
Strontium-90
30 years
Iodine-131
8 days
Other
Cesium, iodine, and strontium pose the biggest threat to the population.
http://www.mext.go.jp/english/radioactivity_level/detail/1303962.htm
75.0 µSv/hr
Fukushima Dai-ichi
250 µSv/hr
1.2 µSv/hr
20 km
30 km
http://www.mext.go.jp/english/radioactivity_level/detail/1303962.htm
Sendai
(Pop: 1 mil)
0.35 µSv/hr
Fukushima Dai-ichi
Maebashi
(Pop: 0.35 mil)
0.11 µSv/hr
Tokyo
(Pop: 13 mil)
0.14 µSv/hr
http://www.mext.go.jp/english/radioactivity_level/detail/1303962.htm
Largest documented
exposure to plant worker
has been 100,000 µSv.
Dose
(Sv)
Dose
(µSv)
0.05
0.5
0.55
0.7
0.75
0.9
1
50,000
500,000
550,000
700,000
750,000
900,000
1,000,000
4
4,000,000
10
10,000,000
20
20,000,000
Health Effect
changes in
blood chemistry
nausea
fatigue
vomiting
hair loss
diarrhea
hemorrhage
possible death
(2 months)
death
(1-2 weeks)
death
(hours-days)
General public not at risk for any short-term health effects.
Above 0.1 Sv (100,000 µSv) the cancer risk can be approximated
by using 5% per Sv.
•  For example, the occupational worker who received a dose of
0.1 Sv has a 0.5% increased risk of developing a cancer.
•  Estimating cancer risks to the general public is difficult because of
the very low dose rates outside of the plant.
•  If radiation levels in Tokyo remained at the current level (0.14
µSv/hr) it would take one month of exposure for residents to
experience the same risks than received from a common dental
X-ray exam.