When the Japanese government heard that the Japanese government had discharged nuclear wastewater into the sea, which contained radioactive tritium, the world was shocked.
On the other hand, as of 2020, the price of 1 gram of tritium exceeded $30,000. And even if you have money to buy it, you don't necessarily have tritium to sell.
While discharging garbage despite the world's opposition and the difficulty of finding a lot of money, what does tritium mean to mankind?
When humans tried to make nuclear fusion controllable
Let's not talk about tritium, let's take a look at the scientific community's understanding and application of nuclear fusion. This reaction, also known as nuclear fusion, can be popularly understood as the transformation of structure and energy of elementary particles.
After the nuclei are reorganized and arranged, they can form the transformation and release of energy. Tritium is not seen in the periodic table and this is because tritium is a branch of hydrogen.
Compared to hydrogen, tritium has two more neutrons inside it, plus one proton, which together make up the entire core of tritium.
Compared with hydrogen, tritium is unstable due to its large mass. In order to achieve stability, tritium releases electrons and energy from the outside world at all times. There is a special word to describe this process - decay.
This decay is also known as β decay because electrons are being released. After decay, tritium will continue to exist in the form of helium-3.
One of the cognate brothers of tritium is deuterium, and the two can be confused by not paying attention to the font. A single neutron h proton makes up deuterium, so it is only one less neutron than tritium, and it is one less "丿" in the font.
These two brothers go through certain conditions to produce a huge release process from mass into energy. When the two are combined, they form a fusion nuclear reaction.
In this process, the respective protons form two protons, the three neutrons form two neutrons, and the other extra neutron is released.
The new composition yields a helium nucleus, and with the addition of the extra neutrons, it stands to reason that their mass has not changed, but only the permutations have changed.
However, in reality, after re-permutation, the mass of a helium nucleus and a neutron is smaller than that of a tritium nucleus and a deuterium nucleus. So, where exactly does the lost part go?
Modern scientists have already given the answer, and the lost part is released in the form of converted energy. The most important thing is that the energy released is quite huge.
So when you see this, you can understand what the principle of nuclear fusion or hydrogen bomb explosion is. However, when the hydrogen bomb was first developed, humans could not control this huge amount of energy, let alone convert it into usable energy.
A clenched fist is nuclear fusion
And to use it, you have to make the fusion reaction controllable. It is precisely this point that the nuclear fusion technology that is now being studied by various major powers.
Speaking of which, some people may think that it seems that the nuclear fusion reaction is also very simple, isn't it the energy conversion that occurs after the combination of tritium and deuterium.
The process is indeed simple, but there are two essential conditions: one is high temperature and the other is high pressure.
I won't say what the specific value is, but just make a simple comparison with the sun. The sun is constantly undergoing nuclear fusion reactions, and its own temperature and pressure can reach the required conditions. Because the sun is big enough, the pressure and temperature inside can reach the standard.
To put it simply, assuming that a person can also meet the requirements of high pressure and high temperature with the strength of a fist, then a nuclear fusion reaction can be formed with a fist.
Back in reality, the mass of the Earth itself is much smaller than that of the Sun, so in its natural state, there will be no nuclear fusion reactions on Earth. On the other hand, the nuclear fusion reaction made by humans is simulated to a limited extent through certain technologies.
Now, in order to master controlled nuclear fusion, it is necessary to control it in addition to simulating the reaction of nuclear fusion. The difficulty index has directly increased a lot, which is why the research has been protracted for a long time.
Returning to the fusion reaction itself, the available elements are hydrogen, tritium, deuterium, helium, lithium, etc. On Earth, the more comprehensive and most controllable by human technology is the nuclear fusion of tritium and deuterium.
So, a new question arises, how many of them are there, and will they be enough in the future?
Deuterium is found in nature and is mainly found in seawater. 0.03 grams of deuterium can be extracted per liter of seawater, and the estimated amount of deuterium on Earth is 45 trillion tons.
In contrast, the amount of tritium in nature is quite small. Some data show that the content of natural tritium on the earth is only about 2 kilograms, and some data show that it is about 3.5 kilograms. But no matter how much it is, its natural content is negligible.
Some people will inevitably wonder, such a small amount, then use a wool.
In fact, it is too much to think about it, because the major countries in the world with technology have never thought of using the pitiful tritium in nature.
For many years, countries with the technology have been manufacturing tritium manually.
How tritium is made
Tritium is used in the nuclear fusion reaction of hydrogen bombs, and countries in the world that have mastered nuclear technology have a variety of hydrogen bombs, and it can also be seen from this that the tritium used by various countries is certainly not from nature, but is made by technology.
So, what are the technologies and raw materials used? In a nutshell, tritium can be produced by bombarding lithium with neutrons. How does it work?
In order to make enough tritium, major countries have developed special equipment for the manufacture of tritium for many years, which is called tritium production reactor.
The main method is to irradiate lithium from fission reactors, a process in which neutrons produced by fission continuously bombard lithium. Through the reaction, tritium and helium can be formed.
It doesn't sound difficult, after all, there are so many nuclear power plants that the reactors in the stations can be used. However, in fact, the reactors used to produce tritium are not the pressurized water reactors commonly found in nuclear power plants, but heavy water reactors, graphite water-cooled reactors or high-temperature gas-cooled reactors.
In other words, such reactors were built additionally, and the main purpose was to produce tritium. According to some sources, at least $5.5 billion is needed to build a tritium-producing heavy water reactor. Not only is it expensive, but so is the cost of security.
In the United States, for example, in the early years, Hanford's graphite reactor was used to make tritium. Later, five more heavy water reactors were built in the Savannah River region.
In the 80s of the last century, the Americans could produce about 10 kilograms of tritium per year. By the 90s, the United States had accumulated at least about 225 kg of tritium.
It was previously estimated that the number of hydrogen and neutron bombs in the United States was 20,000. A hydrogen warhead needs 4 grams of tritium, and a neutron bomb needs 15 grams, so a nuclear bomb consumes about 90 kilograms of tritium.
This also means that there are still about 100 kilograms of tritium in the hands of the Americans that have not been used. It is said that the equipment for making tritium in the United States has stopped operating because the reserves are sufficient.
Russia, another nuclear power, has the same number of thermonuclear warheads as the United States, so it is speculated that its tritium reserves are comparable to those of the United States.
In addition, Britain and France also have a certain amount of tritium reserves. To sum up, if we understand the general manufacturing process of tritium, we can understand why most countries still can't make nuclear weapons.
Moreover, the world's ability to make tritium is not improving, but is still declining.
1 gram of tritium is $30,000
In 2020, Canada handed over five special steel drums to the UK, which contained five more cylinders. The cylinders are the size of a beverage bottle, each containing only a wisp of hydrogen, and the five bottles add up to only 10 grams.
This 10 grams of hydrogen is not simple, it contains radioactive tritium, and the price of 1 gram is 30,000 US dollars.
Theoretically, as long as you master the method of controlling it and let it combine with deuterium, you can produce energy like the sun.
And now the embarrassing part is that there seems to be not enough tritium-producing fusion reactors around the world. To date, the world's main source of commercial tritium is the 19 tritium-uranium nuclear reactors located in Canada.
Reactors in Canada are pressurized heavy water reactors, each producing 0.5 kilograms of tritium per year.
The problem now is that the service life of reactors has an expiration date, and in the next 10 years, at least nine reactors in Canada will have to be decommissioned.
The old reactors have been retired, and new reactors have not yet been built, so industry insiders estimate that the world's tritium stocks are about to bottom out.
According to some data, the global stock of tritium is now 25 kilograms. This amount is different from the reserves of countries such as the United States and Russia mentioned above. It may be that the public data is not true, or it may be that the tritium is publicly counted, and the tritium controlled by the military is not counted.
But in any case, with the current situation that the world is studying controlled nuclear fusion, tritium will indeed not be enough in the next step. And some scientists believe that even if the reactor is rebuilt in the future, the proliferation of tritium will not be realized.
That is, the actual amount of tritium made by the reactor is not really much higher. So in the opinion of scientists, the scarcity of tritium will become more serious with the study of nuclear fusion.
In order to solve the current situation, some privatized nuclear fusion companies in the United States have abandoned the use of tritium as fuel.
These companies decided to use deuterium and helium-3 for nuclear fusion. But when tritium is replaced, the conditions for the nuclear reaction will also change – the temperature required will reach 200 million degrees Celsius.
At present, the fusion reaction of tritium and deuterium already requires a temperature of 150 million degrees Celsius, and it is difficult to believe that if the temperature is increased again, the controlled nuclear fusion researched by human beings can meet the technical requirements.
Therefore, some scientists believe that in decades of controlled nuclear fusion research, most scientists are pursuing the final tipping point breakthrough and arrival, and leave the tritium problem aside, believing that as long as the big problem is solved, the limited scale of tritium can also be solved.
The current situation is that with the shrinking scale of the world's commercial tritium, it will be difficult to find tritium in the future. It's time to think about how to solve this problem.
epilogue
In March 2021, Chengdu launched a special experiment that revolved around the testing of tritium-producing technology.
Although we don't know when the real breakthrough will come, the materials needed for nuclear fusion are also indispensable.
It is foreseeable that in the future, progress has been made in controlled nuclear fusion, and the production capacity of tritium will become the new key.
Resources:
"What is Nuclear Fusion?" National Nuclear Safety Administration, April 6, 2016
"Tritium Production Technology", Popular Science China, April 6, 2016
"1 gram of tritium costs $30,000, and the world's nuclear fusion reactors will suffer the death of tritium?" The Paper, July 2, 2022
"International Thermonuclear Experimental Reactor (ITER) Tritium Experimental Cladding Project Launched in Chengdu" China News Network, March 15, 2021
"Star Nuclide - Tritium", Shanghai Institute of Applied Physics, June 1, 2022