Shulou(Shulou.com)11/24 Report--

This article comes from the official account of Wechat: Earth knowledge Bureau (ID:diqiuzhishiju), text: Bo Yue

In 1905, Einstein put forward the mass-energy equation.

Where c refers to the speed of light, a large number, and squared, even primary school students can feel, this formula reveals an extremely huge energy, which is nuclear energy.

The proposal of mass-energy equation

Laid the foundation for later nuclear energy research.

(figure: wiki) ▼

It is believed that nuclear fusion will usher in an era of unlimited energy in the future, but at present we can only use nuclear fission to generate electricity. Nuclear energy has been developed for less than 70 years and accounts for 10% of the world's electricity sources.

Use nuclear fission energy to generate electricity

It's like opening the door to a new world of power generation, ▼.

By the end of 2022, there will be 55 nuclear power plants in operation in China, accounting for 4.98% of the country's electricity generation. Moreover, China's nuclear power capacity under construction has been the first in the world for many years, and we will have more and more nuclear power. But at the same time, we don't have enough uranium.

So many nuclear power plants have been built

There's not enough uranium, ▼.

Widely used but rare uranium is a key raw material for nuclear fission. Complete fission of one kilogram of uranium 235 will lose about 0.09% of its mass, and the energy released is equivalent to burning 2700 tons of high-quality coal, which is the absolute main "fuel" of nuclear power in the world.

China's import of uranium resources

Maintain a high level of ▼ for many years

In addition to generating electricity, uranium is also widely used in a variety of military and civilian fields.

For example, uranium reactors, atomic bombs and hydrogen bombs on aircraft carriers and submarines are inseparable from uranium. Depleted uranium, a by-product of the uranium enrichment process, can also be used to produce depleted uranium bombs and high-strength armor.

August 1945

The atomic bomb codenamed "Little Boy" exploded over Hiroshima

The city of Hiroshima immediately became a sea of scorching fire.

(figure: nationalmuseum.af.mil) ▼

Armour-piercing projectiles made of metals such as depleted uranium and a small amount of molybdenum

Is one of the main anti-tank weapons.

(figure: wired3) ▼

For example, uranium can be used in agricultural irradiation breeding, production of artificial elements, radiotherapy and angiographic diagnosis. All this further magnifies the consumption of uranium.

Since the 1990s

Uranium resources are in short supply, ▼.

Changes in global uranium resources from 2019 to 2021

Uranium resources are slowly being consumed, ▼.

According to the estimates of the United Nations International Atomic Energy Agency (IAEA) and the Atomic Energy Commission of the Nuclear Energy Administration (NEA) in 2021, China's demand for uranium in that year was as high as 9500 tons, but its own production was only 1800 tons.

Obviously, China's own uranium is not enough. In 2021, China imported more than 13000 tons (13613.9 tons) of uranium resources (U3O8, containing 84.8% uranium), with an import value of 1.31 billion US dollars. This number will continue to expand after that.

In fact, not only China is short of uranium, but also most industrial countries in the world are short of uranium. This highly sensitive shortage of strategic resources is very difficult to explore, exploit and purify.

Kashiwazaki Kariwa Nuclear Power Station in Japan

It used to be the largest nuclear power plant in the world.

Shut down due to multiple potential nuclear leaks

First of all, the content of uranium on Earth is very low, with an average of only 2.7 grams of uranium per ton of crustal material, equivalent to 0.00027%. According to China's current norms, the lowest industrial grade of uranium is 0.05%, that is to say, uranium has to be enriched 185 times to form a usable uranium deposit. If a rich ore with a grade of 0.3% ≥ is to be formed, it should be enriched by 1110 times.

Review the knowledge of high school chemistry.

It can be found that uranium is the 92nd element in the periodic table.

Located in the seventh cycle of the IIIB family, actinides (f region)

At present, the known uranium-bearing ores are mainly pitchblende (U3O8), uraninite (UO2), uraninite (silicate of uranium) and uranium black (oxide of uranium and thorium), and their distribution is extremely uneven.

Natural uranium minerals

Beneath its beautiful appearance

Hides the deadliest radioactive material.

(photo: wiki & mindat) ▼

For example, Australia accounts for 25% of the world's reserves, while China accounts for only 4%.

Hengping-the world finds out the distribution of uranium deposits

(mining cost < 130$/KgU) ▼

However, the costs of different uranium mines vary widely. Internationally, uranium mines are divided into two categories according to mining costs. Uranium mines with costs between US $80 and US $260 per kilogram are high-cost uranium mines, which are dominated by uranium mines in Australia.

Those costing $40 to $80 or less are low-cost uranium mines, with Kazakhstan (40.51 per cent), Canada (17.16 per cent) and Brazil (11.90 per cent) accounting for 2/3. This is also the main source of uranium resources in China.

Above: reliable uranium deposits on behalf of countries all over the world

Next: speculate on the amount of uranium deposits on behalf of countries around the world

(photo: IAEA as of January 2021) ▼

Purification is difficult but demand falls short of demand, both high-cost and low-cost uranium mines are much more expensive than the iron and copper we have introduced before.

On the one hand, it is because of the scarcity of reserves, on the other hand, it is difficult to extract. General metal ores, such as copper ore, as long as the ore is broken, the copper can be extracted by flotation to get refined copper powder for smelting.

And compared with the mining of common metals such as copper mines

The history of large-scale uranium mining is relatively short.

The technology of extracting uranium ore is also relatively less mature.

Uranium mining is much more complicated. if the mined uranium ore is ground into fine powder in a traditional way similar to that of other metal minerals, the uranium concentrate will be extracted from the ore by chemical or physical methods, such as leaching or ion exchange. The main ingredients are uranium trioxide and sodium diuranate, which is the famous "yellow cake".

At present, almost all the countries that mine uranium produce "yellow cake"

But "yellow cake" can not be directly used in nuclear reactors.

It is generally used to enrich uranium.

The other is the rapid development of in-situ uranium leaching in recent years, in which chemicals are injected into the ore belt from surface boreholes, the uranium in the ore is selectively dissolved by chemical reaction, and the leaching solution is extracted from the surface, the result is also "yellow cake".

Model diagram of in situ uranium leaching

Dissolve uranium with chemical reagent, extract leaching solution and then ▼

The brown vats in Operation Red Sea are filled with yellow cakes.

Mainly 238U, its radiation is much lower than that of enriched uranium ▼.

At this point, uranium is about to enter a key link-separation.

Uranium in a uranium concentrate actually contains three natural isotopes, uranium 234, uranium 235 and uranium 238, which must be separated one by one.

Among them, only uranium 235 is the only fission nuclide that exists naturally on earth and is the absolute main fuel of nuclear power plant, but its content in uranium resources is very low, only 0.71%. The non-fissionable uranium 238 accounts for 99.2%. Therefore, uranium concentrate needs isotope separation to make enriched uranium with different purity ratios before it can be used as nuclear fuel.

Nuclear fission of uranium 235

Slow (low energy) neutrons split the nucleus of uranium 235 into two new nuclei

It also produces energy and neutrons.

These newly generated neutrons will hit other uranium 235 atoms.

To form a chain reaction.

(take krypton and barium as examples: Britannica) ▼

Specifically, the yellow cake is converted into uranium hexafluoride (UF6), which is fed into a high-speed rotating centrifuge to separate the lighter uranium 235 and the heavier uranium 238.

The enriched uranium hexafluoride gas is converted into solid uranium oxide to make fuel rods for use in nuclear reactors.

A cascade gas centrifuge for uranium enrichment in an enrichment plant

(figure: energy.gov) ▼

Among them, the content of uranium 235 is very important. if it reaches 3% Mel 5%, it belongs to low-enriched uranium and can be used in nuclear power, 80% is highly enriched uranium, and more than 90% is weapons-grade highly enriched uranium.

Highly enriched uranium billets recovered from waste disposed of by American plants

(figure: EM) ▼

In short, there are many technical barriers to the exploration, mining and purification of uranium, and the cost is very high. Our country's previous starting point is very low, but we can only bear it for the sake of national defense and energy security.

In the 1950s, China began to explore uranium deposits, focusing on granite-type and volcanic-type uranium deposits, focusing on Jiangxi, Hunan, Guangdong and Guangxi.

In 1943, geologist Nan Yanzong went to Guangxi to conduct a mineral geological survey.

The existence of uranium minerals was discovered.

(photo: "the Great Nuclear Industry") ▼

In 1958, the construction of the 711 mine in Chenzhou, Hunan Province began.

711 Mine is the first large-scale uranium deposit in China.

More than 4 million tons of uranium ore have been mined.

(photo: "the Great Nuclear Industry") ▼

With the grid-connected generation of Qinshan Nuclear Power Station in 1991, the history of civil nuclear power in China was opened. since then, the domestic demand for uranium resources has increased rapidly, and the investment in uranium exploration has also increased year by year.

Qinshan Nuclear Power Station located in Haiyan County, Zhejiang Province

Since it was built in 1991, it has been in safe operation for 31 years.

At present, its service life has been extended to 2041.

The deposits explored during this period are mainly sandstone-type uranium deposits, which are mainly developed in basins in northern China, such as Yili Basin, Junggar Basin, Ordos Basin and Songliao Basin.

From 2000 to 2018, new uranium resources have been discovered in Yili, Ordos, Erlian basin and Songliao basin. By January 2021, the amount of uranium resources identified by China is about 330000 tons, including 150000 tons of credible reserves and 180000 tons of inferred reserves, but it is still too little corresponding to our annual demand of nearly 10,000 tons.

Distribution diagram of Hengping-sandstone-type uranium deposits in North China

Sandstone type uranium deposit is an important type of uranium deposit ▼ at present.

China needs more uranium in the future. China's current demand gap is mainly in nuclear power. The total installed capacity of nuclear power plants nearly doubled from 2015 to 2022 (30 million kilowatts to nearly 5700 kilowatts), and uranium consumption (9563 tons) accounted for more than 15 percent of the global consumption in 2021.

Ever-expanding installed capacity

It also corresponds to the increasing demand for uranium, ▼.

But after all, our base is too large, compared with developed countries, the proportion of nuclear power in our country is still very low.

Horizontal screen-Global Distribution of Nuclear Power plants

Compared with developed countries such as Europe and the United States

The number of nuclear power plants in China is still small, ▼.

Construction of nuclear power plants in major countries in the world

Comparatively speaking, the construction of nuclear power plants in China is relatively late.

But the construction speed and loading capacity can be counted as ▼.

Nuclear power accounts for more than 30% of their electricity generation in 10 countries, such as France, Slovakia and Ukraine. France is more than 70%, while China has just reached 5%, this proportion is far from being able to change the current coal-based energy structure.

The development of nuclear energy still has a long way to go, ▼.

Compared with coal power with high carbon emissions and renewable energy with weak stability, nuclear energy is both efficient, clean and stable. Under today's dual-carbon goal, the strategic significance of nuclear power as a clean energy is self-evident. In 2021, for example, the cumulative power generation of nuclear power units in China is 407.141 billion kilowatt-hours, equivalent to a reduction of 115.5805 million tons of standard coal and 302.8209 million tons of carbon dioxide emissions. )

Lucid waters and lush mountains are invaluable assets

The development of nuclear power is the inevitable trend to achieve sustainable development

In late March this year, the National Development and Reform Commission and the National Energy Administration announced the "14th five-year Plan for Modern Energy system", which mentioned that by 2025, the installed capacity of nuclear power operation will reach about 7000 kilowatts.

IAEA and NEA predict that by 2030 and 2040, China's demand for uranium will be as high as 22600 tons and 43400 tons.

In fact, it's not just China.

Some developed countries also exist.

The problem of large demand for uranium but small production ▼

In the face of these two figures, our annual output of 1800 tons is a drop in the bucket, which means that we have to increase our imports, and the main sources of imports at present include Kazakhstan, Namibia, Uzbekistan and Russia.

In 2019, more than half of Kazakhstan's uranium production was sold to China, up to more than 13000 tons. If we can stabilize these major sources and develop some new sources, the future supply of uranium is still very secure.

Our northwestern neighbor Kazakhstan

Really rich in uranium, ▼.

Kazakhstan is the world's largest producer of uranium.

In 2022 alone, the country mined about 16000 tons of uranium

(Inkai uranium map of Kazakhstan: wiki) ▼

Of course, if controlled fusion and thorium-based reactors can be used to generate electricity in large quantities in the future, we can get rid of our dependence on uranium, but until then, the status of uranium is irreplaceable.

Reference:

1. Https://cn.gii.tw/publisher/cri/

two。 National Nuclear Safety Administration (mee.gov.cn)

3. Army Again Turns to Depleted Uranium for New Weaponry | WIRED

4.Kashiwazaki-Kariwa Nuclear Power Station, Japan (power-technology.com)

5. Mapped: The world's nuclear power plants-Carbon Brief

6. Li Qiang, Chen Qing, Wang Jibin, et al. The present situation of world uranium resources and the countermeasures and suggestions for the protection of nuclear power development resources in China [J]. China Mining, 2023 and 32 (3): 1-9.

7. Uranium 2022: Resources, Production and Demand

8. Https://www.china-nea.cn/site/content/38474.html

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