|
The
half-life of radioactive materials
The
half-life of a radioactive material is the time it takes for the activity
to reduce to half of its initial value.
| Number
of half-life periods |
1
|
2
|
3
|
4
|
5
|
6
|
7
|
8
|
9
|
10
|
| Remaining
amount of original activity |
1/2
|
1/4
|
1/8
|
1/16
|
1/32
|
1/64
|
1/128
|
1/256
|
1/512
|
1/1024
|
As
shown in the table above, after 10 half-life periods, only about one thousandth
of the original activity is left!
Each
radioactive material has its own half-life. Some have half-lives of just
a few seconds, others of thousands or even millions of years. Nothing
and no one can change that. Here are some examples of radioactive materials
and their half-lives.
| |
Area
of application |
Half-life |
| Iodine-123 |
nuclear
medicine: diagnostics |
13
hours |
| Iridium-192 |
nuclear
medicine: therapy |
74
days |
| Cobalt-60 |
nuclear
medicine: therapy |
5,27
years |
| Caesium-137 |
nuclear
medicine: therapy |
30
years |
| Carbon-14
|
dating
of materials |
5730
years |
| Plutonium-239 |
nuclear
fuel production |
24.065
years |
| Uranium-235 |
nuclear
fuel production |
704.000.000
years |
If
you don't understand a term, please refer to our glossary.
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