الفرق بين الذرتين (۲۳۸) و (٢٣٥) في كتلة من اليورنيوم .. كتاب في سبيل موسوعة علمية

The difference between the two atoms (238) and (235) in a block of uranium

The difference between the two atoms

The heavier atom (238) does not split. But the lighter atom (235) is the one that splits, and by splitting it is divided into two almost equal parts. Rather, they are two well-known chemical elements.

With the split, radiation comes out.
With radiation, heat comes out.
What is more important than this in our regard is that with the splitting, very small nuclear particles also emerge, forming some of the nuclei of the uranium atom, as well as the nucleus of the element atoms, those particles known as neutrons.

These neutrons come out of the lighter uranium atom (235), and are released quickly. They settle in the belly of the heavier uranium atom, and there are many of them around it (140 heavy atoms for every light atom), and the heavier atom does not undergo sequential splitting.

- atomic bomb :

For a split or explosion to occur, it was necessary to get rid of the heavier uranium (238) and prepare pure lighter uranium (235), and the cost of this extraction was very high. But he produced the bomb. The light uranium atom splits and produces two or three neutrons. It is released and infects more than the nucleus of the uranium atom. From its splitting, more and more neutrons emerge. The division increases in glimpses and becomes an explosion.

This reaction is called a chain reaction, because it consists, like a chain, of links, one link coming after another.

- Atomic reactor:

With this chain reaction, in which the uranium-235 atom is split from one atom after another, a lot of heat is released, which is the goal of using the atom in producing electricity, replacing coal or oil, as we presented.

This reaction that we mentioned is rapid, fleeting, and destructive.
He destroys the earth and everything on it.
One of the reasons for its speed is that we use the active uranium atom, atom 235, pure.

Why do we not use uranium as it is found in nature, and it contains, as we said, a small amount of uranium 238, which is quiet and calm?

Uranium 235 sends its bursts of neutrons, but it sends them very quickly, so they enter the belly of the atom 238 and there it stabilizes, and there is no splitting, no heat, and no electricity.

(An illustrative image of the oxygen atom as a nucleus, and electrons revolve around it in its orbits, just as the planets revolve around the sun. If the atom has eight negative particles, which are electrons, then the nucleus must have eight positive protons that are equivalent to them. Otherwise, the nucleus is particles that have no charge, so they are neutral, they are eight neutrons. )

It comes to mind: Why not slow down the speed of these neutrons, so that if they hit the uranium-238 atom, they split and split it and thus the reaction begins, but slow it down very much.

But how to slow down the speed of neutrons? The answer was that it would calm down if we passed it before it reached its goals in a substance that would calm it down: a stable element that could not be exploded. And they fell on carbon as they fell. They placed layers of it between the layers of natural uranium, and the splitting took place, sequentially, of course, but calmly and quietly. The heat came out of that, not an explosion, but the calmest and most gentle it could be.

But this pile of uranium and coal (in the form of graphite), even if it was small, had a large surface on which many neutrons were lost, as they were wasted in the air. This prevents the pile from becoming larger. The surface of a large heap increases as its volume increases, but not by one factor. The surface does not increase in proportion to the increase in volume. Enlarging the pile preserves many of its neutrons, which are lost at the surface.

That's why this pile of uranium had an unimaginable size. A size sufficient to retain within it a sufficient amount of neutrons, which ensures that it can extract the chain reaction that results from splitting through heat.

The station producing atomic electricity: to the left (in black) is the atomic reactor. Uranium contains black fingers, with carbon (graphite) around it, and its shape in the picture is black dots. Carbon dioxide gas enters the reactor through tubes, exits hot through tubes, then it is pumped out and circulates back into the reactor and exits it, and so on. The picture shows a standing cylinder filled with hot carbon dioxide gas as it exits the reactor. The water circulates in tubes that permeate this hot cylinder with its gas, turning the water into steam and the pressure drives the turbines. These rotate the coils of wire in the magnetic field. The magnet is strong, and electricity is generated in it. It then flows through the wires and is distributed to homes and industries. As for the calming fingers, they regulate the temperature in the reactor.

But isn't it possible, with an increase in size, to increase the output of...
More neutrons than necessary, so we increase the splitting more than we want and produce more heat than we want?

The answer: Yes, it is possible.

For this reason, we insert into this pile of layers, layers of natural uranium, and layers of coal in the form of graphite. We insert sticks of the element cadmium, for example. This has the property of absorbing a lot of neutrons, taking them out of the reaction field, thus slowing down the reaction and reducing the resulting heat.

Or we take these sticks out of the pile, taking them out, thereby increasing the neutrons, increasing the reaction, and increasing the temperature. These cadmium sticks control the resulting heat, increasing it if we want it to increase, and decreasing it if we want it to decrease.