The problem of uranium enrichment! How is enriched uranium refined?

The greater the uranium concentration, the greater the radiation intensity, as long as the electronic equipment checks the abnormal changes in the radiation concentration in the area, it can know that all enriched uranium is the key, and then enriched uranium preparation, popular methods such as centrifuge refining and enrichment, there are also many ways, such as the most common, the technical difficulty is relatively low For example, there is a gas separation method, in which uranium hexafluoride is prepared first (even if a series of processes are used to oxidize and separate uranium in uranium ore with highly active fluorine gas) and then uranium hexafluoride is separated by a centrifuge (the gas is made into a plasma state, Then use the huge difference in the weight of the two nuclei for centrifugal screening, this process has to be repeated again and again, and the concentration of uranium can come up) Those 201 factories in our northwest and a nuclear industrial plant are all doing this... Come to Sichuan, my brother will take you to see the soldiers guarding the cave in the mountains, there is no secret, who doesn't know in the nearby villages -- the old Sichuan flavor Bashu food square ---

What does it mean to enrich uranium to 20%.

You don't understand this, do you?? Politics, political issues. The purpose is to make other countries careful, similar countries are very dangerous, don't try to invade us, and if I am unhappy, I will give you a few nuclear **.

The deterrent effect of nuclear ** is still very large, even the United States does not dare to rashly launch an attack on a nuclear ** country, why do you want me to say??? That's why I want people to know that I'm doing nuclear research...

Enriched uranium refers to uranium metal that has been isotopically refined, and the uranium content exceeds 90% of Guess, and the opposite of starvation is depleted uranium. Enriched uranium can be divided into highly enriched uranium, low enriched uranium and slightly enriched uranium according to the different uranium 235 content.

Uranium is an important chemical compound that is used to generate electricity for nuclear power plants. Theoretically, one kilogram of uranium-235 produces more than 20 terjoules. Most nuclear power plants use enriched uranium fuel with 3% uranium-235.

In life, this element is used in the wood and leather industries, in dyes and dyeing, in photographic chemicals, and in the limb filament used to make stage lighting bulbs.

Uranium is a rare chemical element found in nature and is radioactive. According to the definition of the International Atomic Energy Agency, uranium-235 with an abundance of 3% is low-enriched uranium for power generation in nuclear power plants, and uranium with an abundance of uranium-235 greater than 80% is highly enriched uranium, of which the abundance of more than 90% is called **grade highly enriched uranium, which is mainly used to make nuclear **.

When it comes to enriched uranium abundance, many people must be confused and don't know what it is, so let's talk about what enriched uranium abundance is.

Uranium is a rare chemical element found in nature, and the three isotopes of uranium in natural ores are symbiotic, of which the content of uranium-235 is very low, only about 0 7%. In order to meet the needs of nuclear power and nuclear power, some countries have built uranium enrichment plants, using natural uranium ore as raw materials, using isotope separation methods (diffusion, centrifugal and laser methods, etc.) to separate the three isotopes of natural uranium to improve the abundance of uranium-235 and refine enriched uranium.

According to the definition of the International Atomic Energy Agency, uranium-235 with an abundance of 3% is low-enriched uranium for power generation in nuclear power plants, and uranium with an abundance of uranium-235 greater than 80% is highly enriched uranium, of which the abundance of more than 90% is called **grade highly enriched uranium, which is mainly used to make nuclear **. Obtaining uranium is a very complex series of processes, which need to go through prospecting, mining, beneficiation, leaching, refining, refining and other processes, and enrichment and separation is the last process, which requires a high level of science and technology. It takes 200 tons of uranium ore to obtain 1 kg of ** grade uranium-235.

Because of the nuclear issues involved, uranium enrichment technology is a sensitive technology that is strictly prohibited by the international community from proliferation. In addition to several nuclear powers, Japan, Germany, India, Pakistan, Argentina and other countries have mastered uranium enrichment technology. The gas centrifugal method is usually used to refine enriched uranium, and the gas centrifugal separator is the key equipment, so countries such as the United States usually use the possession of this equipment as a criterion for judging whether a country conducts nuclear research.

At present, nuclear power plants use uranium nuclear fuel. Uranium has 12 isotopes (uranium-226 uranium-240). The uranium-234 does not undergo nuclear fission, and uranium-238 does not normally undergo nuclear fission, while uranium-235, an isotope atom, can easily undergo nuclear fission, or in other words, it is actually uranium-235 that is used as nuclear fuel.

However, the uranium mined from the mine has a very low uranium-235 content, accounting for only the vast majority of uranium-238, which it occupies. This is the equivalent of our briquette factory or oil refinery, where most of the briquettes produced are made of sediment, which of course cannot be burned. According to the results of the study, the content of uranium-235 in uranium nuclear fuel must reach more than 3% before it can be burned.

Therefore, the mined uranium is not directly used as fuel unlike the mined coal, it needs to go through the procedures of purification and enrichment, and the proportion of uranium-235 content is increased before it can be used as fuel.

Enriched uranium refers to uranium metal with more than 90% uranium 235 content after isotope refining, as opposed to depleted uranium.

Uranium enrichment is necessary for both the peaceful use of nuclear energy and the manufacture of nuclear power. Therefore, the IAEA wants to be able to control all uranium enrichment activities in countries around the world in order to prevent the proliferation of nuclear weapons.

Enriched uranium can be divided into highly enriched uranium (HEU) (more than 20%), low-enriched uranium (LEU) (2%-20%) and slightly enriched uranium (SEU) according to the uranium-235 content. If the uranium-235 content exceeds 85%, it is called **grade enriched uranium, which is directly used to make atomic bombs.

A nuclear reactor is mainly composed of the following parts: (1) Active area. This is where the chain reaction takes place, in which nuclear fuel and neutron moderators are placed.

Nuclear fuel refers to fissile material that produces a chain reaction. Natural uranium, enriched uranium (uranium-235 is more abundant than natural uranium), plutonium and uranium-233 are used in the reactor. Moderators are substances used to reduce the velocity of neutrons, because the neutrons released by fission have a high velocity, and uranium-235 is prone to fission with a smaller velocity (thermal neutron).

The ideal moderator is a substance that does not absorb or very few neutrons. Such as heavy water (D2O, compounds of heavy hydrogen and oxygen), graphite, beryllium oxide, etc. For enriched uranium fuel, ordinary water can also be used as a moderator.

In the active zone, the nuclear fuel is generally inserted into the reducer in the shape of a rod or block, and there are also nuclear fuel and the reducer are evenly mixed together. (2) Neutron reflective layer. It is used to block the middle and fly out of the active area to reduce the loss of neutrons, generally graphite or beryllium oxide.

3) Control the regulation system. The speed of the chain reaction is very fast, it can produce about 1,000 neutrons per second, and if left unchecked, it releases a huge amount of energy in a very short time to make uranium**, which is the atomic bomb. Therefore, the control and regulation system is a very critical part of the reactor, which is used to control the speed of the chain reaction, adjust the power of the reactor, and make the reactor start or stop working.

The control system is mainly composed of control rods made of cadmium or boron, a substance with strong neutron absorption, and the corresponding automatic control system. When the reaction is strong, the control rods in the reactor will be inserted deeper, so that more neutrons are absorbed, so that the chain reaction is slowed down; Conversely, pull the control rod out of the active zone a little outward, and the reaction speed will be accelerated. (4) Cooling system.

The vast majority of the energy released by nuclear fission in the reactor is converted into heat. The temperature in the reactor is very high, usually using ordinary water, heavy water, liquid metal steel, etc. as coolant to transport the heat in the reactor, and then through the heat exchange device to turn the water into high-pressure and high-temperature steam, which is used to drive the steam turbine to generate electricity. On the other hand, the cooled coolant is pressed back into the reactor and continues to be used, where it flows in a closed circulatory system.

5) Protective layer. When the nucleus fissions, not only neutrons are released, but also a large number of rays and rays are emitted from the fission products. In order to prevent the harm of these rays to the human body, the outer layer of the reactor should be built with a thick concrete protective layer.

It's uranium, but the uranium-rich content has increased.

Centrifugation, a second-generation method for enriching uranium, is currently under development. The centrifugal method involves passing uranium hexafluoride gas through a hollow cylinder that rotates at high speed. When the diameter of the cylinder is ten centimeters, the rotational speed reaches 6 to 100,000 revolutions per minute.

At such a large speed, the slightly heavier uranium hexafluoride gas molecules composed of uranium-238 are more concentrated near the cylinder wall due to the large centrifugal force, and the slightly lighter uranium-235 gas molecules are more concentrated in the cylinder ** area. The tandem stage required to produce 3 concentrations is only a few tenths of the diffusion method, which is about a few dozens. As a result, the consumption of electrical energy is about one-tenth that of the diffusion method, and the economic scale is only one-tenth of that of the diffusion plant, so the construction period is short, and the construction of a centrifugal plant can be started at the same time as the decision to build a nuclear power plant.

The main problem with centrifugation is that the centrifuge that rotates at high speed makes the centrifugal force of the cylinder high. Due to material constraints, the centrifuge should not be too large, and its production capacity per unit is much lower than that of the diffuser. In the case of the same scale of production, the number of centrifuges is more than dozens of times more than that of diffusers.

As a result, the investment is 30 percent higher than that of a diffusion plant of the same size, and the centrifuge is prone to damage. However, due to the low power consumption and other reasons, the product cost is still 30% lower than that of the diffusion plant. Uranium 235 accounted for only 0 1 in the tailings of the centrifugal plant.

In the early seventies, centrifugal methods were already built in Europe. The fourth diffusion plant planned to be built in Portsmouth by the United States was also converted into a centrifugal plant in 1977, with a designed annual separation capacity of 8,800 tons of separation work, more than half of the first three combined.