With the deepening of the reform of the energy structure, the whole world is the full development of nuclear power, but to make a reactor to produce electricity must have nuclear fuel, but the most common nuclear fuel from uranium.
Uranium ore is very beautiful, known as the ore in the family rose, but few are willing to close it, the reason lies in the radiation.
From the literature, film and television works, and media reports we get a hint, and anything related to nuclear energy has strong radiation and human contact for a long time will cause a variety of symptoms or even death, hence the mere mention of the nuclear talks.
So, whether the uranium ore is also a beautiful poison? We bring a comprehensive explanation and analysis.
See above the uranium deposit, the first question is: a lot of people of the uranium ore have radiation? Poisonous mushroom like beautiful, uranium so beautiful, radiation must be very terrible? Is not can't touch?
First of all, uranium ore has radiation, that is for sure. However, the radiation level and we did not think so terrible. Studies showed that a person in his pocket Chuai about 1 kg of uranium ore, the amount of radiation per day also to wear a luminous watch almost.
In the past, people will be uranium as a toner to produce good-looking glass, which is uranium glass. In the past also used uranium glazed pottery.
Light in the ultraviolet irradiated URANIUM GLASS
Light in the ultraviolet irradiated URANIUM GLASS
Natural uranium ore containing mainly uranium 238 and uranium 235, and the half-life of the two uranium are 4.468 billion years and 7.04 billion years, the half-life of this everlasting, which makes it not so toxic. In addition, when the decay of uranium mainly emitted the Alfa particle, gamma ray is not dangerous.
Alfa decay of atoms, releasing alpha particles
Alpha, beta and gamma rays penetrating demonstration
We can see that in the alpha, beta and gamma, alpha rays penetrating the weakest, a piece of paper can be blocked.
Maybe someone is not very convincing, but never mind, let's look at the picture below.
Uranium purification process of intermediate products - yellow cake
This is an intermediate product of uranium purification process, called "yellow cake", it contains about 80% uranium oxides. You see, the uranium purified all dare not to mention the good catch, it is not the purification of uranium.
Highly enriched uranium metal
In nuclear power plants nuclear fuel
This is the use of nuclear power plants nuclear fuel, it is by the above yellow cake to purify, wearing a pair of gloves, you can still hands on them.
In uranium and uranium content is actually very low, from the dean of the school of nuclear science and technology, Lanzhou University, Professor Wang Suo Wu, he in an open class tells us that the uranium content low to a ton of ore not to mention the one kilogram of uranium, is content of less than 0.1%, and content if higher than 0.05% basically can be mined, which with shalitaojin have why to distinguish? There is no difference.
The purified uranium can be used in hand, radiation levels so you can think of a piece of uranium ore.
Here, estimated that there will be people think so: in that case, the uranium mining, it does not have to take what measures?
No, on the contrary, when uranium mining protection heavy. This is why?
Very simple, uranium buried in the ground, although the half-life of uranium over hundreds of millions of years, but the large amount of uranium in uranium mine. More important is, uranium mines buried in the ground, it is sealed undertakes, and gathered the many radioactive, but pay attention to, the radioactive than uranium 238 and uranium 235 directly, but after the decay of uranium into radon is mainly caused by radon. The radon half-life of only 3.8235 days, compared with the half-life of uranium, it is far too short, uranium gathered a lot of radon, this is very dangerous, so it is necessary to take protective measures.
In short sentence is a piece of uranium ore radiation did not so terrible, of course, if you put it perennially on your pillow, that is not enough.
Uranium in China
Our country is not a small amount of uranium rich countries, not to say, the grade is not high. According to the World Nuclear Association in 2013, the world's countries known recoverable uranium are listed in the following table:
The world can be mined uranium ratio
Our country's uranium resources exploitation of uranium resources in the world accounted for about 4%. Although this year also found in some uranium deposits, but the data on the little floating.
It is much more difficult than shalitaojin
For use in nuclear power plants nuclear fuel is uranium uranium 235, not 238. However, in natural uranium (note that natural uranium not uranium ore, it is derived from a little with the uranium in uranium ores), uranium 235 only 0.72%, the content of uranium 238 more than 99.2%, and uranium refining is to raise the concentration of uranium 235.
The proportion of natural uranium in uranium and uranium 235 238
The representative of natural uranium, the blue part indicates the proportion of uranium 238, red represents 235 uranium.
The proportion of low enriched uranium in uranium and uranium 235 238
The representative of low enriched uranium, the red part of the uranium 235 accounted for 3% to 4%, low enriched uranium is mainly used for nuclear power plant.
The proportion of highly enriched uranium in uranium and uranium 235 238
The representative of highly enriched uranium, the red part of the uranium 235 accounted for about 90%, mainly used for nuclear weapons.
Natural uranium in almost all of the uranium 238, to increases the concentration of uranium 235, this is really too difficult, because they belong to the same elements, is only a difference of three neutrons and their chemical properties are almost the same!
How to separate?
In the past, when the technology is not very advanced, mainly by gas diffusion method. The principle is to put the natural uranium into uranium hexafluoride.
The molecular structure of uranium hexafluoride
The uranium in uranium hexafluoride, possibly is uranium 238, may also be uranium 235, but we now know that 99% of the possible is uranium 238. Uranium hexafluoride is made. Then the uranium hexafluoride heating to make it into a gas, then look uranium 235 separated in these gases, how to do?
So, if a uranium hexafluoride gas molecules in the uranium uranium 235, then the gas molecules to light some light three neutrons, so gas motion, it will run faster, it seems to be the mixture of flour and iron powder together, you blow a, flour will certainly go in front. In addition, if the you in the room were dropping a drop of vinegar and perfume, because the fragrance molecules to light, so the spread quickly, so we will be the first to smell the perfume.
Of course, this is just the analogy only, in fact, the difficulty of separating uranium 235 is much greater, because it only lost 3 neutrons. So, the use of gas diffusion separation of uranium 235 efficiency is very low, energy consumption is huge, very spectacular building.
The United States in the early years of Oak Ridge gas diffusion plant
In addition to gas diffusion, and centrifugal separation method, its principle and the gas diffusion method, still according to the uranium 238 than uranium 235 so little for the.
Separation method of centrifuge
With the centrifuge enrichment plant (DOE)
Schematic diagram of centrifuge separation method, the particles represent the deep blue -238 containing uranium hexafluoride, representative uranium light blue -235.
The uranium hexafluoride into the centrifuge, per minute up to 40000 to 60000 RPM in uranium 235 because a uranium 238 light containing uranium 235 uranium hexafluoride in centrifuge near the hinge, and from the shaft slightly farther is containing uranium 238 uranium hexafluoride. Only 1/10 centrifuge separation gas diffusion law need power, efficiency is much higher.
Gas centrifuge in transit (United States Department of energy)
Hi, this is true, even if it is refined gold, since ancient times, humans have never so much trouble too.
But what's to be done, human beings can not wear a gold ring, a gold necklace, but a second also cannot do without electricity!