Radioactivity

Lecture 24

Chernobyl and Fukushima

Nuclear accidents There is no fool-prove technical system, or in short “Shit happens”! Accidents are not avoidable but the likely-hood or the risk should be minimized by appropriate safety features.

Fukushima Daiichi 2011 earthquake Chernobyl 1986 operator error Three Mile Island 1978 operator error Enrico Fermi Unit 1 1966 malfunction of cooling cycle SL-1 1961 operator error Sodium Reactor Experiment 1959 malfunction of cooling cycle Windscale 1957 operator error

Risk assessment

Health Risk Est. life

expectancy lost

Smoking 20 cigs a day 6 years

Overweight (15%) 2 years

Alcohol (US Ave) 1 year

All Accidents 207 days

All Natural Hazards 7 days

Occupational dose (300 mrem/yr) 15 days

Occupational dose (1 rem/yr) 51 days

Chernobyl and Fukushima

Tsunami wave height falsely claimed as spread of radioactive contamination

Emitted fission products

Release to the Environment

Release to the Atmosphere

T1/2

76h

8d

2.3h

21h

T1/2

5.3d

2y

13d

30y

134Cs down to 18%, the rest gone except 137C, down to 89%

according to the decay law: y

TeNyN

52ln

02/15

Tsunami and Radioactivity

Peak values: 3104 Bq/m3

Pre Fukushima values: 3 Bq/m3

Average human dose: 0.5mSv/y

=0.06 Sv/h

Radioactivity level in Tokyo

Contamination of Japan in Sv/h

Average human exposure 0.5 mSv/y =0.06 Sv/h

Ramsar: 140 Sv/h

Time evolution of 137Cs T1/2=30y

Black: western pacific Green: North America

Light blue: Hawaii Dark blue: Baja California

Red: Aleutian Islands 10 PBq peak value

kBq/m2

Ci/km2

Chernobyl

Average value: 1-100 kBq/m2

Mostly 137Cs, T1/2=30y 50% down

Forest Fires at Chernobyl Woods in April and August 2015

Release in April-May 2015

Release in August 2015

Exposure of Central Europe

Average human exposure 0.5 mSv/y = 0.04 mSv/month

Total = 0.08 mSv Ramsar: 260 Sv/y = 22mSv/month

Comparison with typical human exposure values

1mSv=100mRem

Near Chernobyl

Near Fukushima 300