Those elements whose nuclear are unstable try to become stable by emitting radioactive rays. The nucleus of uranium-235 used as fuel in nuclear power plants is unstable. As a result, uranium-235 is trying to become stable by emitting radioactive rays. This process can go on for hundreds of billions of years depending on the element. What is the lifetime of uranium-235 used in nuclear power plants and why is this uranium-235 removed from nuclear power plants every three to five years. Today we are for it.
All radioactive elements have many characteristics, one of them is half-life. The half-life of an atom is the time it takes for half of the electrons in the atom of an element to break. Suppose you have 500 bricks out of which the time taken to break 250 bricks is called half life. You will be surprised to know that:
The half-life of uranium-238 isotope is 400 crore years.
The half-life of uranium-235 isotope is 70 crore years.
And the half-life of uranium-234 isotope is 25 thousand years.
235 grams of uranium contains 6.022*10^23 atoms. Which will be 602,200,000,000,000,000,000,000+ t. This number is huge. It is said about this number that "If all the people of the world start counting from their birth and counting until the time of their death, they will not be able to finish counting this number. And many people give the example of its magnitude and say that if this amount of mustard seeds were spread all over the world is given.Then the mustard seeds will rise up to our knees.
So you can easily guess how big the number is. Here is an example on this topic. Suppose you have this amount of money and if you spend 100 crore rupees every second. But to spend this amount of money you have to live for 19 billion years. Which is absolutely impossible. Now for the convenience of calculation we do not assume that the number of atoms in 235 grams of uranium is only 200. Half of these 200 atoms ie 100 atoms will take 70 million years to decay. 100 more atoms will remain. And it will take another 70 million years to break this atom. Now there will be 50 more atoms from this 100 and it will take another 70 million years to break these 50 atoms. 50 more atoms will remain. It will take another 70 million years to break these 50 atoms. From now there will be 25 more atoms left. And so the process goes on and on and on for a long time. So imagine how long it would take to break down a uranium atom in this way. And as such T is only for 235. Where as the amount used in nuclear power plants is much higher than this.
Now one question may surely come in your mind and that is why the uranium bundle is changed every three to five years? The point here is that after installing the uranium bundle in the nuclear power plant, it is used to collect the required heat from it. But after three to five years of use it no longer produces enough heat to be commercially profitable. The decay rate of uranium decreases with time. As a result, the amount of heat energy is reduced. A very small fraction of the total energy contained in uranium we can use is wasted. However, scientists are trying different ways to use the energy from uranium more efficiently. Uranium bundles must be kept in a cool place at all times after they are removed from the nuclear power plant. And at the same time that place has to be protected. So that the radioactive rays (α, β and γ rays) emitted from uranium do not come into contact with the atmosphere.
This process is done inside the nuclear power plant which is called cooling base. The cooling base is basically a bowl containing a large amount of water. And the uranium bundles are immersed in the water of that baby. And this water is kept cold all the time. Uranium bundles are kept in the cooling base for about 10 years. Then they are cast with concrete. Then they are called nuclear waste. Nuclear waste is one of the world's biggest headaches today. However, nuclear waste does not heat up as much after a while. But they will emit radioactive rays for billions of years. Which is a serious threat to the environment and fauna. This nuclear waste can even lead to the destruction of human civilization.