The advent of information technology has changed the way humans live, and this change can be said to be extremely transformative. Imagine how boring life would be if you "went back to before liberation" and lived without a TV, computer, or mobile phone. So, our generation is undoubtedly lucky, after all, we have all enjoyed the benefits of the big explosion of technology.
What is controlled nuclear fusion?
When it comes to the word "nuclear", many people first think of atomic bombs or nuclear radiation, in short, it seems to be some bad effects, quite a "smell nuclear discoloration" meaning. But in fact, nuclear energy is a very important energy source in the future, it not only releases more energy than traditional fossil energy, but also its pollution is extremely low, of course, this refers to the energy prepared by controlled nuclear fusion. Conventional nuclear fission, its nuclear waste is still highly radioactive.
nuclear power plant
Nuclear fusion can also be called thermonuclear reaction, the principle is to put relatively small mass atoms, such as helium atoms, under extremely high pressure and temperature, so that they combine or collide, so that heavier cores are produced, followed by mass loss. In simple terms, it is the process of having two lighter nuclei coalesce into a heavier one, in which energy is released.
Because the mass of the atom must be relatively light, the requirements for raw materials used for nuclear fusion reactions are still very high. Scientists have found that there are elements in nature that can easily achieve fusion reactions, both of which are isotopes of hydrogen, respectively, deuterium and tritium, which is also called heavy hydrogen, and tritium is called super heavy hydrogen.
It is worth mentioning that the interior of the sun has also been undergoing nuclear fusion reactions, which allows it to release huge amounts of energy, and the fusion of deuterium and tritium has been on the sun for many years. Based on this finding, people have given controlled nuclear fusion a very interesting nickname, called "artificial sun", of course, many people also jokingly call it "boiling water". No matter which one, it reflects that the requirements for its raw materials and preparation conditions are very high.
It can be seen that if humans want to polymerize two atomic nuclei, they need a device that can produce "high temperature and high pressure", otherwise they will fall into the situation that even if they have raw materials, they cannot complete nuclear fusion. The tokamak device can help us achieve this, as for the Chinese EAST that everyone hears, it is actually part of the hyper-tokamak reactor.
Tokamak device
On the other hand, the content and properties of raw materials, deuterium and tritium, are still quite different in nature. You may have heard the saying that "nuclear fusion energy is inexhaustible", and the inexhaustible element here is deuterium, which is a colorless and odorless flammable gas at room temperature. Importantly, deuterium is widely present in seawater, estimated at 40 trillion tons, and about 0.03 grams of deuterium per liter of seawater, which seems "reassuring".
But there is not so much of the isotope tritium of another type of hydrogen, which has very little stock in nature, and most of it is mainly artificially prepared by nuclear reactions. But from the above-mentioned response methods, it is indispensable. So, once controlled nuclear fusion is achieved, will it use up the tritium on Earth? After all, there are only a few kilograms in nature.
Superheaved hydrogen: tritium
First, let's take a look at what this seemingly scarce element really is. Tritium, like the deuterium mentioned above, is one of the isotopes of hydrogen, and another member of the isotope family of hydrogen is krypton, which is the main component of hydrogen, accounting for about 99.98% of ordinary hydrogen. It can be seen that the remaining 0.02% is deuterium and tritium, and only deuterium is accurate. Because in natural hydrogen, the content of tritium is 1×10^-15%.
Isotope of hydrogen
Tritium consists of one proton and two neutrons, and unlike the colorless and odorless harmlessness of deuterium, it is radioactive. In addition, tritium has an important property, which is why it is so rare, that is, it undergoes β decay, and its half-life is about 12.43 years. In other words, even if tritium had ever appeared in nature, it would have only been kept for about 12 years, a half-life that prevented it from surviving for long.
Therefore, tritium is generally produced by nuclear reaction, and tritium can be obtained by using neutrons to bombard lithium. Specifically, lithium carbonate or lithium fluoride alloy is used as a target, and tritium is obtained from it after bombardment, and its reaction formula is Li+n→4He+3H. This is not the end of the year, and it is necessary to enrich the output of tritium to 99% using the thermal diffusion method.
Knowing the nature of tritium and its main source, the question mentioned earlier is easy to answer. Even if controlled nuclear fusion is really achieved, there is no need to worry about the depletion of raw materials on the earth when these kilograms of tritium are used up.
After all, these kilograms of tritium are all prepared by hand, which is not natural in nature, if it can really achieve "controlled nuclear fusion" in the future, scientists will definitely ensure that tritium is enough, and definitely not because tritium is not enough is the technology into the dilemma of "smart women are difficult to cook without rice".
Moreover, deuterium-tritium fusion is actually the first generation of fusion, the second generation of nuclear fusion reaction is to react with deuterium and helium 3, and the third generation of fusion is to let ammonia 3 and helium 3 fuse reaction.
But in any case, these reactions are facing certain difficulties, some are very demanding for temperature, some are not stocked on the earth, such as helium 3, but helium 3 is a lot on the moon, which is probably the main reason why humans are eager to establish a lunar base to mine!
Tritium can be prepared, but is very expensive
If controlled nuclear fusion technology is a field that countries around the world are keen to study today, then the preparation process of its raw material tritium is also of concern. Therefore, the fusion tritium process has been studied since a very early age, and after a long period of efforts, it has achieved certain results.
Like the early United States, there are several laboratories to study tritium processes, the most representative of which should be the Los Alamos Laboratory, where the U.S. Department of Energy built a tritium system experimental device that simulates the fusion reactor tritium process in 1977 to study how to effectively prepare tritium.
The work in Japan is mainly carried out in the Japan Atomic Energy Institute and the University of Tokyo, and the Japanese government has also invested in the construction of tritium treatment laboratories, but the system is still relatively small compared to the United States.
As mentioned above, the mainland's EAST is located in Hefei, and on December 30, 2021, a new record of 1056 seconds of high-temperature plasma operation has been achieved, which shows that the mainland's attention to the field of controlled nuclear fusion is still very high. Therefore, how to effectively prepare tritium is of course also within the scope of our planning and consideration.
Researchers at the China Academy of Engineering Physics have published relevant papers to elaborate on the exquisite technology of tritium lifting process in tritium-containing heavy water. For example, special electrolysis technology, gas-liquid catalytic exchange technology, hydrogen-oxygen composite technology and so on.
In a CANDU type power reactor or an experimental research reactor with heavy water as a reflective layer, neutrons interact with deuterium (D) in heavy water to produce a by-product tritium, which will accumulate a certain amount of tritium in heavy water as the reactor operating time increases.
In short, at present, human beings have mastered the relevant methods of preparing tritium. However, it is still difficult to produce in large quantities, and it costs a lot of money. However, with the progress and development of science and technology, I believe that scientists can overcome these problems in the future, when mankind will surely usher in a new era.
The polluting nature of tritium
In the previous article, when introducing the basic properties of tritium, we mentioned that it has two characteristics, one of which is that the 12-year half-life makes it difficult for it to survive in nature, so the content is very small. The second is that it is radioactive and harmful to the human body. Tritium currently exists mainly in the following three chemical forms, namely tritium, tritium water and tritium methane.
However, compared with the high-risk radioactive elements we are familiar with, tritium is relatively low in toxicity. However, if the amount is too much, it may still cause harm to the human body, and it will have biological effects after entering the human body, and the specific degree of damage should be considered from many aspects such as intake and pathway.
To this end, scientists have conducted a number of experimental studies, mainly to study the carcinogenic effect, mutagenic effect and teratogenic effect of tritium. In the experimental study of carcinogenic effects, it was found that tritium does have a certain carcinogenic effect on the body. Teratogenic effects are more pronounced, for example, tritium water exposure will cause lab rats to have mental retardation and a reduced rate of conditioned reflexes.
Gao Weimin et al. injected different concentrations of tritium water into adult rats with a pregnancy of 13 days through intraperitoneal injection, and the cumulative dose of tritium absorption in each group of mice in the first three days of birth was 0.044, 0.088 and 0.264Gy, respectively. Experimental results proved that rats received continuous irradiation with tritium water during pregnancy, and their baby mice would produce teratogenicity.
It can be seen that although tritium is not very toxic, if it is exposed to people for a long time, it will still have a bad impact on the body. Therefore, the mainland nuclear power plant has been paying great attention to the emission of tritium in operation, and will effectively manage and control the value of tritium to maintain it within the national standard limit.
What controlled nuclear fusion realization means for humanity
The reason why human beings are so concerned about controlled nuclear fusion, in addition to feeling that technology and the development of change has not occurred for a long time, the most important thing is the urgency of the current environment and the ambitious pursuit of future goals. Therefore, controlled nuclear fusion, as a new energy source, has extraordinary significance for human beings.
First of all, its energy is large and very stable. If controlled nuclear fusion can be achieved, then our journey to the universe will be more smooth, after all, after abandoning the use of extremely inefficient and high-weight traditional fossil energy, human spacecraft will be able to fly farther in a limited time. In other words, at that time, our "cosmic navigation era" will be truly opened, and now it is just a circle at the doorstep of the home.
Second, the burning of fossil fuels has placed a great burden on the earth's environment. However, it is impossible for us not to use energy and bring human technology to a standstill. So, how do you get the best of both worlds? Controlled nuclear fusion is the best of both worlds, after all, it is not only very abundant, because the most important thing on the earth is seawater. And it's also pollution-free, so we can replace the highly polluting traditional energy sources and reduce the pressure of environmental pollution.
It can be seen that once controlled nuclear fusion is achieved, our lives will change. In the past, people's plans for the journey of the universe and the stars and the sea could be realized, not only that, but we were also able to protect the earth's environment. Sometimes, development does not mean destruction, and if controlled nuclear fusion can be achieved, then the Earth's environment will return to its former vitality.