13.08.2020

What do you know about half-life?

What is half-life?

 

Our team believes that radiation is not such a dangerous phenomenon if you understand what it is. As experienced dosimetrists with a huge amount of knowledge behind them said, there is no need to be afraid of radiation. You need to understand it. This statement is absolutely true!


Every morning, on the way to the Chernobyl zone, our experienced guides give instructions for our tourists, the essence of which is to convey the correct information, break stereotypes and dispel stupid myths about burning clothes after the tour. One of several important blocks of information is just the block about radiation safety standards. In this block of rules such a term as "half-life" often appears. Just today we will talk in our article about such a phenomenon and try to explain to you, our dear readers, in simple and human language, what it is.


The number of nuclei in radioactive elements tend to decay over time. The term "half-life" is nothing more than a time period during which the number of nuclei of a radioactive element will be halved.


Quite often, people do not quite correctly understand the concept of half-life. More often than not, everyone thinks that if a radioactive substance has a half-life of 1 hour, this means that after 1 hour its first half will disintegrate, and after another 1 hour - the second half, and this substance will completely disappear (disintegrate).


For radionuclides with a half-life, for example, only 1 hour, this means that after 1 hour its amount will be 2 times less than the initial one, after 2 hours - 4 times, after 3 hours - 8 times, etc., but will never completely disappear. The amount of radiation emitted from this substance will decrease with the same proportions. In this case, if it is known what and in what amount of radioactive elements create radiation in a given place at a given time, it is possible to predict what kind of radiation situation will be in the near future. By the way, this was the technique used by scientists during the liquidation of the consequences of the accident at the Chernobyl nuclear power plant.


Each radioactive element has its own half-life. It can last for millions of years or for a fraction of a second. Again, it all depends on the type of radioactive element. And immediately answering the rather frequent question of our tourists "when will it be clean here?", We answer: - never. So, for example, the half-life of Cesium 137 is 30 years; Strontium 90 - 29 years old; more than 24 thousand years. It is with these and many other radioactive elements that the entire exclusion zone is stained. Most importantly, the half-life of the radionuclides is constant and cannot be changed.


Nuclei formed during radioactive decay, in turn, can also be radioactive. For example, radioactive Radon-222 owes its origin to radioactive Uranium-238.
Sometimes there are claims that radioactive waste in storage facilities will completely decay in 300 years. This is not true. It's just that this time will be about 10 half-lives of cesium-137, one of the most widespread technogenic radionuclides, and in 300 years its radioactivity in waste will decrease by almost 1000 times, but, unfortunately, it will not disappear.