Humanity has always been in search of new sources of energy that can solve many problems. However, they are not always safe. So, in particular, those widely used today, although they are capable of generating simply colossal amounts of electrical energy that everyone needs, still carry within them mortal danger. But, in addition to peaceful purposes, some countries on our planet have learned to use it for military purposes, especially to create nuclear warheads. This article will discuss the basis of such destructive weapons, the name of which is weapons-grade plutonium.
Brief information
This compact form of the metal contains a minimum of 93.5% of the 239Pu isotope. Weapons-grade plutonium was named so so that it could be distinguished from its “reactor counterpart.” In principle, plutonium is always formed in absolutely any nuclear reactor, which, in turn, operates on low-enriched or natural uranium, containing, for the most part, the 238U isotope.
Application in the military industry
Weapons-grade plutonium 239Pu is the basis of nuclear weapons. At the same time, the use of isotopes with mass numbers 240 and 242 is irrelevant, since they create a very high neutron background, which ultimately complicates the creation and design of highly effective nuclear ammunition. In addition, the plutonium isotopes 240Pu and 241Pu have a significantly shorter half-life compared to 239Pu, so plutonium parts become very hot. It is in this regard that engineers are forced to additionally add elements to remove excess heat into nuclear weapons. By the way, 239Pu in its pure form is warmer than the human body. It is also impossible not to take into account the fact that the products of the decay process of heavy isotopes subject the crystal lattice of the metal to harmful changes, and this quite naturally changes the configuration of plutonium parts, which, in the end, can cause complete failure nuclear explosive device.
By and large, all of the above difficulties can be overcome. And in practice, tests have already been carried out more than once on the basis of “reactor” plutonium. But it should be understood that in nuclear weapons their compactness, low dead weight, durability and reliability are by no means the least important. In this regard, they use exclusively weapons-grade plutonium.
Design features of production reactors
Almost all plutonium in Russia was produced in reactors equipped with a graphite moderator. Each of the reactors is built around cylindrically assembled blocks of graphite.
When assembled, the graphite blocks have special slots between them to ensure continuous circulation of the coolant, which uses nitrogen. The assembled structure also has vertically located channels created for the passage of water cooling and fuel through them. The assembly itself is rigidly supported by a structure with openings under the channels used to discharge already irradiated fuel. Moreover, each of the channels is located in a thin-walled tube cast from a lightweight and extremely strong aluminum alloy. Most of The described channels have 70 fuel rods. Cooling water flows directly around the fuel rods, removing excess heat from them.
Increasing the power of production reactors
Initially, the first Mayak reactor operated with a thermal power of 100 MW. However, the main leader of the Soviet nuclear weapons program made a proposal, which was that the reactor in winter time worked with a power of 170-190 MW, and in the summer - 140-150 MW. This approach allowed the reactor to produce almost 140 grams of precious plutonium per day.
In 1952, full-fledged research work was carried out in order to increase the production capacity of operating reactors using the following methods:
- By increasing the flow of water used for cooling and flowing through the cores of a nuclear plant.
- By increasing resistance to the phenomenon of corrosion that occurs near the channel liner.
- Reducing the rate of graphite oxidation.
- Increasing temperature inside fuel cells.
As a result, the throughput of circulating water increased significantly after the gap between the fuel and the channel walls was increased. We also managed to get rid of corrosion. For this, the most suitable aluminum alloys were selected and sodium bichromate began to be actively added, which ultimately increased the softness of the cooling water (pH became about 6.0-6.2). The oxidation of graphite ceased to be a pressing problem after nitrogen was used to cool it (previously only air was used).
In the late 1950s, the innovations were fully realized in practice, reducing the highly unnecessary inflation of uranium caused by radiation, significantly reducing the heat hardening of uranium rods, improving cladding resistance, and increasing production quality control.
Production at Mayak
"Chelyabinsk-65" is one of those very secret plants where weapons-grade plutonium was created. The enterprise had several reactors, and we will take a closer look at each of them.
Reactor A
The installation was designed and created under the leadership of the legendary N. A. Dollezhal. It operated with a power of 100 MW. The reactor had 1149 vertically arranged control and fuel channels in a graphite block. The total weight of the structure was about 1050 tons. Almost all channels (except 25) were loaded with uranium, the total mass of which was 120-130 tons. 17 channels were used for control rods, and 8 for experiments. Maximum indicator The design heat release of the fuel cell was 3.45 kW. At first, the reactor produced about 100 grams of plutonium per day. The first metallic plutonium was produced on April 16, 1949.
Technological disadvantages
Almost immediately, quite serious problems were identified, which consisted of corrosion of aluminum liners and coating of fuel cells. The uranium rods also swelled and became damaged, causing cooling water to leak directly into the reactor core. After each leak, the reactor had to be stopped for up to 10 hours in order to dry the graphite with air. In January 1949, the channel liners were replaced. After this, the installation was launched on March 26, 1949.
Weapons-grade plutonium, the production of which at reactor A was accompanied by all sorts of difficulties, was produced in the period 1950-1954 with an average unit power of 180 MW. Subsequent operation of the reactor began to be accompanied by more intensive use, which quite naturally led to more frequent shutdowns (up to 165 times a month). As a result, the reactor was shut down in October 1963 and resumed operation only in the spring of 1964. It completely completed its campaign in 1987 and over the entire period of many years of operation it produced 4.6 tons of plutonium.
AB reactors
It was decided to build three AB reactors at the Chelyabinsk-65 enterprise in the fall of 1948. Their production capacity was 200-250 grams of plutonium per day. The chief designer of the project was A. Savin. Each reactor consisted of 1996 channels, 65 of which were control channels. The installations used a technical innovation - each channel was equipped with a special coolant leak detector. This move made it possible to change the liners without stopping the operation of the reactor itself.
The first year of operation of the reactors showed that they produced about 260 grams of plutonium per day. However, already from the second year of operation, the capacity was gradually increased, and already in 1963 its figure was 600 MW. After the second overhaul, the problem with the liners was completely resolved, and the power was already 1200 MW with an annual production of plutonium of 270 kilograms. These indicators remained until the reactors were completely closed.
AI-IR reactor
The Chelyabinsk enterprise used this installation during the period from December 22, 1951 to May 25, 1987. In addition to uranium, the reactor also produced cobalt-60 and polonium-210. Initially, the facility produced tritium, but later began to produce plutonium.
Also, the plant for processing weapons-grade plutonium had in operation reactors operating on heavy water and a single light water reactor (its name was “Ruslan”).
Siberian giant
"Tomsk-7" was the name of the plant, which housed five reactors for the creation of plutonium. Each of the units used graphite to slow down the neutrons and ordinary water to ensure proper cooling.
The I-1 reactor operated with a cooling system in which water passed through once. However, the remaining four installations were equipped with closed primary circuits equipped with heat exchangers. This design made it possible to additionally generate steam, which in turn helped in the production of electricity and heating of various living spaces.
Tomsk-7 also had a reactor called EI-2, which, in turn, had a dual purpose: it produced plutonium and, due to the steam generated, generated 100 MW of electricity, as well as 200 MW of thermal energy.
Important information
According to scientists, the half-life of weapons-grade plutonium is about 24,360 years. Huge number! In this regard, the question becomes especially acute: “How to properly deal with the waste from the production of this element?” The best option is considered to be the construction of special enterprises for the subsequent processing of weapons-grade plutonium. This is explained by the fact that in this case the element can no longer be used for military purposes and will be under human control. This is exactly how weapons-grade plutonium is disposed of in Russia, but the United States of America has taken a different route, thereby violating its international obligations.
Thus, the American government proposes to destroy highly enriched material not by industrial means, but by diluting plutonium and storing it in special containers at a depth of 500 meters. It goes without saying that in this case the material can easily be removed from the ground at any time and used again for military purposes. According to Russian President Vladimir Putin, initially the countries agreed to destroy plutonium not by this method, but to carry out disposal at industrial facilities.
The cost of weapons-grade plutonium deserves special attention. According to experts, tens of tons of this element may well cost several billion US dollars. And some experts have even estimated 500 tons of weapons-grade plutonium at as much as 8 trillion dollars. The amount is really impressive. To make it clearer how much money this is, let’s say that in the last ten years of the 20th century, Russia’s average annual GDP was $400 billion. That is, in fact, the real price of weapons-grade plutonium was equal to twenty annual GDP of the Russian Federation.
| Plutonium | |
|---|---|
| Atomic number | 94 |
| Appearance simple substance | |
| Properties of the atom | |
| Atomic mass (molar mass) |
244.0642 a. e.m. (/mol) |
| Atomic radius | 151 pm |
| Ionization energy (first electron) |
491.9(5.10) kJ/mol (eV) |
| Electronic configuration | 5f 6 7s 2 |
| Chemical properties | |
| Covalent radius | n/a pm |
| Ion radius | (+4e) 93 (+3e) 108 pm |
| Electronegativity (according to Pauling) |
1,28 |
| Electrode potential | Pu←Pu 4+ -1.25V Pu←Pu 3+ -2.0V Pu←Pu 2+ -1.2V |
| Oxidation states | 6, 5, 4, 3 |
| Thermodynamic properties of a simple substance | |
| Density | 19.84 /cm³ |
| Molar heat capacity | 32.77 J/(mol) |
| Thermal conductivity | (6.7) W/( ·) |
| Melting temperature | 914 |
| Heat of Melting | 2.8 kJ/mol |
| Boiling temperature | 3505 |
| Heat of vaporization | 343.5 kJ/mol |
| Molar volume | 12.12 cm³/mol |
| Crystal lattice of a simple substance | |
| Lattice structure | monoclinic |
| Lattice parameters | a=6.183 b=4.822 c=10.963 β=101.8 |
| c/a ratio | — |
| Debye temperature | 162 |
Plutonium- a radioactive chemical element of the actinide group, widely used in production nuclear weapons(the so-called “weapons-grade plutonium”), and also (experimentally) as nuclear fuel for nuclear reactors for civil and research purposes. The first artificial element obtained in quantities available for weighing (1942).
The table on the right shows the main properties of α-Pu, the main allotropic modification of plutonium at room temperature and normal pressure.
History of plutonium
The plutonium isotope 238 Pu was first artificially produced on February 23, 1941 by a group of American scientists led by Glenn Seaborg by irradiating nuclei uranium deuterons. It is noteworthy that only after artificial production plutonium was discovered in nature: 239 Pu is usually found in negligible quantities in uranium ores as a product of the radioactive transformation of uranium.
Finding plutonium in nature
In uranium ores, as a result of the capture of neutrons (for example, neutrons from cosmic radiation) by uranium nuclei, neptunium(239 Np), the β-decay product of which is natural plutonium-239. However, plutonium is formed in such microscopic quantities (0.4-15 parts Pu per 10 12 parts U) that its extraction from uranium ores is out of the question.
origin of name plutonium
In 1930, the astronomical world was excited by wonderful news: a new planet had been discovered, the existence of which had long been spoken of by Percival Lovell, an astronomer, mathematician and author of fantastic essays about life on Mars. Based on many years of movement observations Uranus And Neptune Lovell came to the conclusion that beyond Neptune in solar system there must be another, ninth planet, forty times farther from the Sun than the Earth.
This planet, the orbital elements of which Lovell calculated back in 1915, was discovered in photographs taken on January 21, 23 and 29, 1930 by astronomer K. Tombaugh at the Flagstaff Observatory ( USA) . The planet was named Pluto. The 94th element, artificially obtained at the end of 1940 from nuclei, was named after this planet, located in the solar system beyond Neptune. atoms uranium a group of American scientists led by G. Seaborg.
Physical properties plutonium
There are 15 isotopes of plutonium - B the largest quantities isotopes with mass numbers from 238 to 242 are obtained:
238 Pu -> (half-life 86 years, alpha decay) -> 234 U,
This isotope is used almost exclusively in RTGs for space purposes, for example, on all vehicles that have flown beyond the orbit of Mars.
239 Pu -> (half-life 24,360 years, alpha decay) -> 235 U,
This isotope is most suitable for the construction of nuclear weapons and fast neutron nuclear reactors.
240 Pu -> (half-life 6580 years, alpha decay) -> 236 U, 241 Pu -> (half-life 14.0 years, beta decay) -> 241 Am, 242 Pu -> (half-life 370,000 years, alpha -decay) -> 238 U
These three isotopes do not have serious industrial significance, but are obtained as by-products when energy is produced in nuclear reactors using uranium, through the sequential capture of several neutrons by uranium-238 nuclei. Isotope 242 is most similar in nuclear properties to uranium-238. Americium-241, produced by the decay of the isotope 241, was used in smoke detectors.
Plutonium is interesting because it undergoes six phase transitions from its solidification temperature to room temperature, more than any other chemical element. With the latter, the density increases abruptly by 11%, as a result, plutonium castings crack. The alpha phase is stable at room temperature, the characteristics of which are given in the table. For application, the delta phase, which has a lower density, and a cubic body-centered lattice is more convenient. Plutonium in the delta phase is very ductile, while the alpha phase is brittle. To stabilize plutonium in the delta phase, doping with trivalent metals is used (gallium was used in the first nuclear charges).
Applications of plutonium
The first plutonium-based nuclear charge was detonated on July 16, 1945 at the Alamogordo test site (under test). code name Trinity).
Biological role of plutonium
Plutonium is highly toxic; The maximum permissible concentration for 239 Pu in open water bodies and the air of working rooms is 81.4 and 3.3 * 10 −5 Bq/l, respectively. Most isotopes of plutonium have a high ionization density and a short particle path length, so its toxicity is due not so much to its chemical properties (plutonium is probably no more toxic in this regard than other heavy metals), but rather to the ionizing effect on surrounding body tissues. Plutonium belongs to a group of elements with particularly high radiotoxicity. In the body, plutonium produces large irreversible changes in the skeleton, liver, spleen, kidneys, and causes cancer. The maximum permissible content of plutonium in the body should not exceed tenths of a microgram.
Artworks related to the theme plutonium
- Plutonium was used for the De Lorean DMC-12 machine in the movie Back to the Future as fuel for a flux accumulator to travel to the future or the past.
— The charge of the atomic bomb detonated by terrorists in Denver, USA, in Tom Clancy’s “All the Fears of the World” was made from plutonium.
— Kenzaburo Oe “Notes of a Pinch Runner”
— In 2006, Beacon Pictures released the film Plutonium-239 ( "Pu-239")
Chemistry
Plutonium Pu - element No. 94 is associated with very great hopes and very great fears of humanity. These days it is one of the most important, strategically important elements. It is the most expensive of the technically important metals - it is much more expensive than silver, gold and platinum. He is truly precious.
Background and history
In the beginning there were protons - galactic hydrogen. As a result of its compression and subsequent nuclear reactions, the most incredible “ingots” of nucleons were formed. Among them, these “ingots,” there were apparently those containing 94 protons. Theorists' estimates suggest that about 100 nucleon formations, which include 94 protons and from 107 to 206 neutrons, are so stable that they can be considered the nuclei of isotopes of element No. 94.
But all these isotopes - hypothetical and real - are not so stable as to survive to this day since the formation of the elements of the solar system. The half-life of the longest-lived isotope of element No. 94 is 81 million years. The age of the Galaxy is measured in billions of years. Consequently, the “primordial” plutonium had no chance of surviving to this day. If it was formed during the great synthesis of the elements of the Universe, then those ancient atoms of it “extinct” long ago, just as dinosaurs and mammoths became extinct.
In the 20th century new era, AD, this element was recreated. Of the 100 possible isotopes of plutonium, 25 have been synthesized. The nuclear properties of 15 of them have been studied. Four found practical use. And it was opened quite recently. In December 1940, when uranium was irradiated with heavy hydrogen nuclei, a group of American radiochemists led by Glenn T. Seaborg discovered a previously unknown alpha particle emitter with a half-life of 90 years. This emitter turned out to be the isotope of element No. 94 with a mass number of 238. In the same year, but a few months earlier, E.M. McMillan and F. Abelson obtained the first element heavier than uranium, element number 93. This element was called neptunium, and element 94 was called plutonium. The historian will definitely say that these names originate in Roman mythology, but in essence the origin of these names is rather not mythological, but astronomical.
Elements No. 92 and 93 are named after the distant planets of the solar system - Uranus and Neptune, but Neptune is not the last in the solar system, even further lies the orbit of Pluto - a planet about which almost nothing is still known... A similar construction We also see on the “left flank” of the periodic table: uranium - neptunium - plutonium, however, humanity knows much more about plutonium than about Pluto. By the way, astronomers discovered Pluto just ten years before the synthesis of plutonium - almost the same period of time separated the discoveries of Uranus - the planet and uranium - the element.
Riddles for cryptographers
The first isotope of element No. 94, plutonium-238, has found practical application these days. But in the early 40s they didn’t even think about it. It is possible to obtain plutonium-238 in quantities of practical interest only by relying on the powerful nuclear industry. At that time it was just in its infancy. But it was already clear that by releasing the energy contained in the nuclei of heavy radioactive elements, it was possible to obtain weapons of unprecedented power. The Manhattan Project appeared, which had nothing more than a name in common with the famous New York area. This was the general name for all work related to the creation of the first atomic bombs in the United States. It was not a scientist, but a military man, General Groves, who was appointed head of the Manhattan Project, who “affectionately” called his highly educated charges “broken pots.”
The leaders of the “project” were not interested in plutonium-238. Its nuclei, like the nuclei of all plutonium isotopes with even mass numbers, are not fissile by low-energy neutrons, so it could not serve as a nuclear explosive. Nevertheless, the first not very clear reports about elements No. 93 and 94 appeared in print only in the spring of 1942.
How can we explain this? Physicists understood: the synthesis of plutonium isotopes with odd mass numbers was a matter of time, and not too long. Odd isotopes were expected to, like uranium-235, be able to support a nuclear chain reaction. Some people saw them as potential nuclear explosives, which had not yet been received. And these hopes plutonium, unfortunately, he justified it.
In encryption of that time, element No. 94 was called nothing less than... copper. And when the need arose for copper itself (as a structural material for some parts), then in the codes, along with “copper,” “genuine copper” appeared.
"The Tree of the Knowledge of Good and Evil"
In 1941, the most important isotope of plutonium was discovered - an isotope with mass number 239. And almost immediately the theorists' prediction was confirmed: plutonium-239 nuclei were fissioned by thermal neutrons. Moreover, during their fission, no less number of neutrons were produced than during the fission of uranium-235. Ways to obtain this isotope in large quantities were immediately outlined...
Years have passed. Now it’s no secret to anyone that the nuclear bombs stored in arsenals are filled with plutonium-239 and that these bombs are enough to cause irreparable damage to all life on Earth.
There is a widespread belief that humanity was clearly in a hurry with the discovery of the nuclear chain reaction (the inevitable consequence of which was the creation of a nuclear bomb). You can think differently or pretend to think differently - it’s more pleasant to be an optimist. But even optimists inevitably face the question of the responsibility of scientists. We remember the triumphant June day of 1954, the day when the first nuclear power plant in Obninsk. But we cannot forget the morning of August 1945 - “the morning of Hiroshima”, “the black day of Albert Einstein”... We remember the first post-war years and the rampant atomic blackmail - the basis of American policy in those years. But hasn’t humanity experienced a lot of troubles in subsequent years? Moreover, these anxieties were intensified many times over by the consciousness that if a new outbreak broke out World War, nuclear weapons will be launched.
Here you can try to prove that the discovery of plutonium did not add fear to humanity, that, on the contrary, it was only useful.
Let's say it happened that for some reason or, as they would say in the old days, by the will of God, plutonium was inaccessible to scientists. Would our fears and concerns then be reduced? Nothing happened. Nuclear bombs would be made from uranium-235 (and in no less quantity than from plutonium), and these bombs would “eat up” even larger parts of the budgets than now.
But without plutonium there would be no prospects for the peaceful use of nuclear energy on a large scale. There simply would not be enough uranium-235 for a “peaceful atom”. The evil inflicted on humanity by the discovery of nuclear energy would not be balanced, even partially, by the achievements of the “good atom.”
How to measure, what to compare with
When a plutonium-239 nucleus is split by neutrons into two fragments of approximately equal mass, about 200 MeV of energy is released. This is 50 million times more energy released in the most famous exothermic reaction C + O 2 = CO 2. “Burning” in a nuclear reactor, a gram of plutonium gives 2,107 kcal. In order not to break tradition (and in popular articles, the energy of nuclear fuel is usually measured in non-systemic units - tons of coal, gasoline, trinitrotoluene, etc.), we also note: this is the energy contained in 4 tons of coal. And an ordinary thimble contains an amount of plutonium energetically equivalent to forty carloads of good birch firewood.
The same energy is released during the fission of uranium-235 nuclei by neutrons. But the bulk of natural uranium (99.3%!) is the isotope 238 U, which can only be used by turning uranium into plutonium...
Energy of stones
Let us evaluate the energy resources contained in natural uranium reserves.
Uranium is a trace element and is found almost everywhere. Anyone who has visited, for example, Karelia, will probably remember granite boulders and coastal cliffs. But few people know that a ton of granite contains up to 25 g of uranium. Granites make up almost 20% of the weight earth's crust. If we count only uranium-235, then a ton of granite contains 3.5-105 kcal of energy. It's a lot, but...
Processing granite and extracting uranium from it requires spending an even larger amount of energy - about 106-107 kcal/t. Now, if it were possible to use not only uranium-235, but also uranium-238 as an energy source, then granite could be considered at least as a potential energy raw material. Then the energy obtained from a ton of stone would be from 8-107 to 5-108 kcal. This is equivalent to 16-100 tons of coal. And in this case, granite could provide people with almost a million times more energy than all the chemical fuel reserves on Earth.
But uranium-238 nuclei do not fission by neutrons. For nuclear energy this isotope is useless. More precisely, it would be useless if it could not be converted into plutonium-239. And what is especially important: practically no energy needs to be spent on this nuclear transformation - on the contrary, energy is produced in this process!
Let's try to figure out how this happens, but first a few words about natural plutonium.
400 thousand times less than radium
It has already been said that isotopes of plutonium have not been preserved since the synthesis of elements during the formation of our planet. But this does not mean that there is no plutonium in the Earth.
It is formed all the time in uranium ores. By capturing neutrons from cosmic radiation and neutrons produced by the spontaneous fission of uranium-238 nuclei, some - very few - atoms of this isotope turn into atoms of uranium-239. These nuclei are very unstable; they emit electrons and thereby increase their charge. Neptunium, the first transuranium element, is formed. Neptunium-239 is also highly unstable, and its nuclei emit electrons. In just 56 hours, half of the neptunium-239 turns into plutonium-239, the half-life of which is already quite long - 24 thousand years.
Why is plutonium not extracted from uranium ores?? Low, too low concentration. “Production per gram - labor per year” - this is about radium, and plutonium in ores is 400 thousand times less than radium. Therefore, it is extremely difficult not only to mine, but even to detect “terrestrial” plutonium. This was done only after the physical and chemical properties of plutonium produced in nuclear reactors were studied.
Plutonium is accumulated in nuclear reactors. In powerful neutron streams, the same reaction occurs as in uranium ores, but the rate of formation and accumulation of plutonium in the reactor is much higher - a billion billion times. For the reaction of converting ballast uranium-238 into energy-grade plutonium-239, optimal (within acceptable) conditions are created.
If the reactor operates on thermal neutrons (recall that their speed is about 2000 m per second, and their energy is a fraction of an electronvolt), then from a natural mixture of uranium isotopes an amount of plutonium is obtained that is slightly less than the amount of “burnt out” uranium-235. A little, but less, plus the inevitable losses of plutonium during its chemical separation from irradiated uranium. In addition, the nuclear chain reaction is maintained in the natural mixture of uranium isotopes only until a small fraction of uranium-235 is consumed. Hence the logical conclusion: a “thermal” reactor using natural uranium - the main type of currently operating reactors - cannot ensure the expanded reproduction of nuclear fuel. But what is promising then? To answer this question, let’s compare the course of the nuclear chain reaction in uranium-235 and plutonium-239 and introduce another physical concept into our discussions.
The most important characteristic of any nuclear fuel is the average number of neutrons emitted after the nucleus has captured one neutron. Physicists call it the eta number and denote it by the Greek letter q. In “thermal” reactors on uranium, the following pattern is observed: each neutron generates an average of 2.08 neutrons (η = 2.08). Plutonium placed in such a reactor under the influence of thermal neutrons gives η = 2.03. But there are also reactors that operate on fast neutrons. It is useless to load a natural mixture of uranium isotopes into such a reactor: a chain reaction will not occur. But if the “raw material” is enriched with uranium-235, it can be developed in a “fast” reactor. In this case, c will already be equal to 2.23. And plutonium, exposed to fast neutron fire, will give η equal to 2.70. We will have “extra half a neutron” at our disposal. And this is not at all little.
Let's see what the resulting neutrons are spent on. In any reactor, one neutron is needed to maintain a nuclear chain reaction. 0.1 neutrons are absorbed by the construction materials of the installation. The “excess” is used to accumulate plutonium-239. In one case the “excess” is 1.13, in the other it is 1.60. After the “burning” of a kilogram of plutonium in a “fast” reactor, colossal energy is released and 1.6 kg of plutonium is accumulated. And uranium in a “fast” reactor will provide the same energy and 1.1 kg of new nuclear fuel. In both cases, expanded reproduction is evident. But we must not forget about the economy.
Due to the series technical reasons The plutonium breeding cycle takes several years. Let's say five years. This means that the amount of plutonium per year will increase by only 2% if η=2.23, and by 12% if η=2.7! Nuclear fuel is capital, and any capital should yield, say, 5% per annum. In the first case there are large losses, and in the second there are large profits. This primitive example illustrates the “weight” of every tenth of a number in nuclear energy.
Something else is also important. Nuclear power must keep pace with growing energy demand. Calculations show that his condition is fulfilled in the future only when η approaches three. If the development of nuclear energy sources lags behind society’s energy needs, then there will be two options left: either “slow down progress” or take energy from some other sources. They are known: thermonuclear fusion, annihilation energy of matter and antimatter, but are not yet technically accessible. And it is not known when they will become real sources of energy for humanity. And the energy of heavy nuclei has long become a reality for us, and today plutonium, as the main “supplier” of atomic energy, has no serious competitors, except, perhaps, uranium-233.
Sum of many technologies
When, as a result of nuclear reactions, the required amount of plutonium has accumulated in uranium, it must be separated not only from the uranium itself, but also from fission fragments - both uranium and plutonium, burned up in the nuclear chain reaction. In addition, the uranium-plutonium mass also contains a certain amount of neptunium. The most difficult things to separate are plutonium from neptunium and rare earth elements (lanthanides). Plutonium as chemical element unlucky to some extent. From a chemist's point of view, the main element of nuclear energy is just one of fourteen actinides. Like rare earth elements, all elements of the actinium series are very close to each other in chemical properties, the structure of the outer electron shells of the atoms of all elements from actinium to 103 is the same. What’s even more unpleasant is that the chemical properties of actinides are similar to the properties of rare earth elements, and among the fission fragments of uranium and plutonium there are more than enough lanthanides. But then element 94 can be in five valence states, and this “sweets the pill” - it helps to separate plutonium from both uranium and fission fragments.
The valency of plutonium varies from three to seven. Chemically, the most stable (and therefore the most common and most studied) compounds are tetravalent plutonium.
The separation of actinides with similar chemical properties - uranium, neptunium and plutonium - can be based on the difference in the properties of their tetra- and hexavalent compounds.
There is no need to describe in detail all the stages of the chemical separation of plutonium and uranium. Usually their separation begins with the dissolution of uranium bars in nitric acid, after which the uranium, neptunium, plutonium and fragmentation elements contained in the solution are “separated” using traditional radiochemical methods - precipitation, extraction, ion exchange and others. The final plutonium-containing products of this multi-stage technology are its dioxide PuO 2 or fluorides - PuF 3 or PuF 4. They are reduced to metal with barium, calcium or lithium vapor. However, the plutonium obtained in these processes is not suitable for the role of a structural material - fuel elements of nuclear power reactors cannot be made from it, and the charge of an atomic bomb cannot be cast. Why? The melting point of plutonium - only 640°C - is quite achievable.
No matter what “ultra-gentle” conditions are used to cast parts from pure plutonium, cracks will always appear in the castings during solidification. At 640°C, solidifying plutonium forms a cubic crystal lattice. As the temperature decreases, the density of the metal gradually increases. But then the temperature reached 480°C, and then suddenly the density of plutonium drops sharply. The reasons for this anomaly were discovered quite quickly: at this temperature, plutonium atoms are rearranged in the crystal lattice. It becomes tetragonal and very “loose”. Such plutonium can float in its own melt, like ice on water.
The temperature continues to fall, now it has reached 451°C, and the atoms again formed a cubic lattice, but located at a greater distance from each other than in the first case. With further cooling, the lattice first becomes orthorhombic, then monoclinic. In total, plutonium forms six different crystalline forms! Two of them are distinguished by a remarkable property - a negative coefficient of thermal expansion: with increasing temperature, the metal does not expand, but contracts.
When the temperature reaches 122°C and the plutonium atoms rearrange their rows for the sixth time, the density changes especially dramatically - from 17.77 to 19.82 g/cm 3 . More than 10%!
Accordingly, the volume of the ingot decreases. If the metal could still resist the stresses that arose at other transitions, then at this moment destruction is inevitable.
How then to make parts from this amazing metal? Metallurgists alloy plutonium (adding small amounts of the required elements to it) and obtain castings without a single crack. They are used to make plutonium charges for nuclear bombs. The weight of the charge (it is determined primarily by the critical mass of the isotope) is 5-6 kg. It could easily fit into a cube with an edge size of 10 cm.
Heavy isotopes of plutonium
Plutonium-239 also contains in small quantities higher isotopes of this element - with mass numbers 240 and 241. The 240 Pu isotope is practically useless - it is ballast in plutonium. From 241, americium is obtained - element No. 95. In its pure form, without admixture of other isotopes, plutonium-240 and plutonium-241 can be obtained by electromagnetic separation of plutonium accumulated in the reactor. Before this, plutonium is additionally irradiated with neutron fluxes with strictly defined characteristics. Of course, all this is very complicated, especially since plutonium is not only radioactive, but also very toxic. Working with it requires extreme caution.
One of the most interesting isotopes of plutonium, 242 Pu, can be obtained by irradiating 239 Pu for a long time in neutron fluxes. 242 Pu very rarely captures neutrons and therefore “burns out” in the reactor more slowly than other isotopes; it persists even after the remaining isotopes of plutonium have almost completely turned into fragments or turned into plutonium-242.
Plutonium-242 is important as a “raw material” for the relatively rapid accumulation of higher transuranium elements in nuclear reactors. If plutonium-239 is irradiated in a conventional reactor, then it will take about 20 years to accumulate microgram amounts of, for example, California-252 from grams of plutonium.
It is possible to reduce the accumulation time of higher isotopes by increasing the intensity of the neutron flux in the reactor. This is what they do, but then you cannot irradiate large amounts of plutonium-239. After all, this isotope is divided by neutrons, and too much energy is released in intense flows. Additional difficulties arise with reactor cooling. To avoid these difficulties, it would be necessary to reduce the amount of plutonium irradiated. Consequently, the yield of californium would again become scanty. Vicious circle!
Plutonium-242 is not fissile by thermal neutrons, it can be irradiated in large quantities in intense neutron fluxes... Therefore, in reactors, all elements from americium to fermium are “made” from this isotope and accumulated in weight quantities.
Every time scientists managed to obtain a new isotope of plutonium, the half-life of its nuclei was measured. The half-lives of isotopes of heavy radioactive nuclei with even mass numbers change regularly. (This cannot be said for odd isotopes.)
As the mass increases, the “lifetime” of the isotope also increases. A few years ago highest point This chart was plutonium-242. And then how will this curve go - with a further increase in the mass number? To point 1, which corresponds to a lifetime of 30 million years, or to point 2, which corresponds to 300 million years? The answer to this question was very important for geosciences. In the first case, if 5 billion years ago the Earth consisted entirely of 244 Pu, now only one atom of plutonium-244 would remain in the entire mass of the Earth. If the second assumption is true, then plutonium-244 may be in the Earth in concentrations that could already be detected. If we were lucky enough to find this isotope in the Earth, science would receive the most valuable information about the processes that took place during the formation of our planet.
Half-lives of some isotopes of plutonium
A few years ago, scientists were faced with the question: is it worth trying to find heavy plutonium in the Earth? To answer it, it was necessary first of all to determine the half-life of plutonium-244. Theorists could not calculate this value with the required accuracy. All hope was only for experiment.
Plutonium-244 accumulated in a nuclear reactor. Element No. 95 - americium (isotope 243 Am) was irradiated. Having captured a neutron, this isotope turned into americium-244; americium-244 in one out of 10 thousand cases turned into plutonium-244.
The preparation of plutonium-244 was isolated from a mixture of americium and curium. The sample weighed only a few millionths of a gram. But they were enough to determine the half-life of this interesting isotope. It turned out to be equal to 75 million years. Later, other researchers clarified the half-life of plutonium-244, but not by much - 81 million years. In 1971, traces of this isotope were found in the rare earth mineral bastnäsite.
Many attempts have been made by scientists to find an isotope of the transuranium element that lives longer than 244 Pu. But all attempts remained in vain. At one time, hopes were placed on curium-247, but after this isotope was accumulated in the reactor, it turned out that its half-life is only 16 million years. It was not possible to break the record of plutonium-244 - it is the longest-lived of all isotopes of transuranium elements.
Even heavier isotopes of plutonium undergo beta decay, and their lifetimes range from a few days to a few tenths of a second. We know for sure that all isotopes of plutonium are formed in thermonuclear explosions, up to 257 Pu. But their lifetime is tenths of a second, and many short-lived isotopes of plutonium have not yet been studied.
Possibilities of the first plutonium isotope
And finally - about plutonium-238 - the very first of the “man-made” isotopes of plutonium, an isotope that at first seemed unpromising. It is actually a very interesting isotope. It is subject to alpha decay, that is, its nuclei spontaneously emit alpha particles - helium nuclei. Alpha particles generated by plutonium-238 nuclei carry high energy; dissipated in matter, this energy turns into heat. How big is this energy? Six million electron volts are released from the decay of one atomic nucleus plutonium-238. In a chemical reaction, the same energy is released when several million atoms are oxidized. An electricity source containing one kilogram of plutonium-238 develops a thermal power of 560 watts. The maximum power of a chemical current source of the same mass is 5 watts.
There are many emitters with similar energy characteristics, but one feature of plutonium-238 makes this isotope irreplaceable. Alpha decay is usually accompanied by strong gamma radiation, penetrating through large layers of matter. 238 Pu is an exception. The energy of gamma rays accompanying the decay of its nuclei is low, and it is not difficult to protect against it: the radiation is absorbed by a thin-walled container. The probability of spontaneous fission of nuclei of this isotope is also low. Therefore, it has found application not only in current sources, but also in medicine. Batteries containing plutonium-238 serve as a source of energy in special cardiac stimulants.
But 238 Pu is not the lightest known isotope of element No. 94; isotopes of plutonium have been obtained with mass numbers from 232 to 237. The half-life of the lightest isotope is 36 minutes.
Plutonium is a big topic. The most important things are told here. After all, it has already become a standard phrase that the chemistry of plutonium has been studied much better than the chemistry of such “old” elements as iron. Whole books have been written about the nuclear properties of plutonium. The metallurgy of plutonium is another amazing section of human knowledge... Therefore, you should not think that after reading this story, you truly learned plutonium - the most important metal of the 20th century.
- HOW TO CARRY PLUTONIUM. Radioactive and toxic plutonium requires special care during transportation. A container was designed specifically for its transportation - a container that is not destroyed even in aircraft accidents. It is made quite simply: it is a thick-walled vessel made of of stainless steel, surrounded by a mahogany shell. Obviously, plutonium is worth it, but imagine how thick the walls must be if you know that a container for transporting only two kilograms of plutonium weighs 225 kg!
- POISON AND ANTIDOTE. On October 20, 1977, Agence France Presse reported: found chemical compound, capable of removing plutonium from the human body. A few years later, quite a lot became known about this compound. This complex compound is a linear carboxylase catechinamide, a substance of the chelate class (from the Greek “chela” - claw). The plutonium atom, free or bound, is captured in this chemical claw. In laboratory mice, this substance was used to remove up to 70% of absorbed plutonium from the body. It is believed that in the future this compound will help extract plutonium from both production waste and nuclear fuel.
What do we want to learn today? How much does 1 cube of plutonium weigh, the weight of 1 m3 of plutonium? No problem, you can find out the number of kilograms or the number of tons at once, mass (weight of one cubic meter, weight of one cube, weight of one cubic meter, weight 1 m3) are indicated in Table 1. If anyone is interested, you can skim the small text below and read some explanations. How is the amount of substance, material, liquid or gas we need measured? Except for those cases when it is possible to reduce the calculation of the required quantity to the counting of goods, products, elements in pieces (piece counting), it is easiest for us to determine the required quantity based on volume and weight (mass). In everyday life, the most common unit of volume measurement for us is 1 liter. However, the number of liters suitable for household calculations is not always an applicable way to determine the volume for business activities. In addition, liters in our country have not become a generally accepted “production” and trading unit for measuring volume. One cubic meter, or in its abbreviated version - one cube, turned out to be a fairly convenient and popular unit of volume for practical use. We are accustomed to measuring almost all substances, liquids, materials and even gases in cubic meters. It's really convenient. After all, their costs, prices, rates, consumption rates, tariffs, supply contracts are almost always tied to cubic meters (cubes), and much less often to liters. No less important for practical activities is knowledge of not only the volume, but also the weight (mass) of the substance occupying this volume: in this case we are talking about how much 1 cubic meter weighs (1 cubic meter, 1 cubic meter, 1 m3). Knowing mass and volume gives us a fairly complete idea of quantity. Site visitors, when asking how much 1 cube weighs, often indicate specific units of mass in which they would like to know the answer to the question. As we noticed, most often they want to know the weight of 1 cube (1 cubic meter, 1 cubic meter, 1 m3) in kilograms (kg) or tons (t). Essentially, you need kg/m3 or t/m3. These are closely related units that define quantity. In principle, a fairly simple independent conversion of weight (mass) from tons to kilograms and vice versa is possible: from kilograms to tons. However, as practice has shown, for most site visitors a more convenient option would be find out immediately how many kilograms 1 cubic (1 m3) of plutonium weighs or how many tons 1 cubic (1 m3) of plutonium weighs, without converting kilograms into tons or vice versa - the number of tons into kilograms per cubic meter (one cubic meter, one cubic meter, one m3). Therefore, in Table 1 we indicated how much 1 cubic meter (1 cubic meter, 1 cubic meter) weighs in kilograms (kg) and tons (t). Choose the table column that you need yourself. By the way, when we ask how much 1 cubic meter (1 m3) weighs, we mean the number of kilograms or the number of tons. However, from a physical point of view, we are interested in density or specific gravity. The mass of a unit volume or the amount of substance contained in a unit volume is bulk density or specific gravity. In this case bulk density and specific gravity of plutonium. Density and specific gravity in physics are usually measured not in kg/m3 or tons/m3, but in grams per cubic centimeter: g/cm3. Therefore, in Table 1, specific gravity and density (synonyms) are indicated in grams per cubic centimeter (g/cm3)
Many of our readers associate the hydrogen bomb with an atomic one, only much more powerful. In fact, this is a fundamentally new weapon, which required disproportionately large intellectual efforts for its creation and works on fundamentally different physical principles.
The only thing that the atomic and hydrogen bombs have in common is that both release colossal energy hidden in the atomic nucleus. This can be done in two ways: to divide heavy nuclei, for example, uranium or plutonium, into lighter ones (fission reaction) or to force the lightest isotopes of hydrogen to merge (fusion reaction). As a result of both reactions, the mass of the resulting material is always less than the mass of the original atoms. But mass cannot disappear without a trace - it turns into energy according to Einstein’s famous formula E=mc 2.
To create an atomic bomb, a necessary and sufficient condition is to obtain fissile material in sufficient quantities. The work is quite labor-intensive, but low-intellectual, lying closer to the mining industry than to high science. The main resources for the creation of such weapons are spent on the construction of giant uranium mines and enrichment plants. Evidence of the simplicity of the device is the fact that less than a month passed between the production of the plutonium needed for the first bomb and the first Soviet nuclear explosion.
Let us briefly recall the operating principle of such a bomb, known from school physics courses. It is based on the property of uranium and some transuranium elements, for example, plutonium, to release more than one neutron during decay. These elements can decay either spontaneously or under the influence of other neutrons.
The released neutron can leave the radioactive material, or it can collide with another atom, causing another fission reaction. When a certain concentration of a substance (critical mass) is exceeded, the number of newborn neutrons, causing further fission of the atomic nucleus, begins to exceed the number of decaying nuclei. The number of decaying atoms begins to grow like an avalanche, giving birth to new neutrons, that is, a chain reaction occurs. For uranium-235, the critical mass is about 50 kg, for plutonium-239 - 5.6 kg. That is, a ball of plutonium weighing slightly less than 5.6 kg is just a warm piece of metal, and a mass of slightly more lasts only a few nanoseconds.
The actual operation of the bomb is simple: we take two hemispheres of uranium or plutonium, each slightly less than the critical mass, place them at a distance of 45 cm, cover them with explosives and detonate. The uranium or plutonium is sintered into a piece of supercritical mass, and a nuclear reaction begins. All. There is another way to start a nuclear reaction - to compress a piece of plutonium with a powerful explosion: the distance between the atoms will decrease, and the reaction will begin at a lower critical mass. All modern atomic detonators operate on this principle.
The problems with the atomic bomb begin from the moment we want to increase the power of the explosion. Simply increasing the fissile material is not enough - as soon as its mass reaches a critical mass, it detonates. Various ingenious schemes were invented, for example, to make a bomb not from two parts, but from many, which made the bomb begin to resemble a gutted orange, and then assemble it into one piece with one explosion, but still, with a power of over 100 kilotons, the problems became insurmountable.
But fuel for thermonuclear fusion does not have a critical mass. Here the Sun, filled with thermonuclear fuel, hangs overhead, a thermonuclear reaction has been going on inside it for a billion years - and nothing explodes. In addition, during the synthesis reaction of, for example, deuterium and tritium (heavy and superheavy isotope of hydrogen), energy is released 4.2 times more than during the combustion of the same mass of uranium-235.
The making of the atomic bomb was more experimental than theoretical process. The creation of a hydrogen bomb required the emergence of completely new physical disciplines: the physics of high-temperature plasma and ultra-high pressures. Before starting to construct a bomb, it was necessary to thoroughly understand the nature of the phenomena that occur only in the core of stars. No experiments could help here - the researchers’ tools were only theoretical physics And higher mathematics. It is no coincidence that a gigantic role in the development of thermonuclear weapons belongs to mathematicians: Ulam, Tikhonov, Samarsky, etc.
Classic super
By the end of 1945, Edward Teller proposed the first hydrogen bomb design, called the "classic super". To create the monstrous pressure and temperature necessary to start the fusion reaction, it was supposed to use a conventional atomic bomb. The “classic super” itself was a long cylinder filled with deuterium. An intermediate “ignition” chamber with a deuterium-tritium mixture was also provided - the synthesis reaction of deuterium and tritium begins at a lower pressure. By analogy with a fire, deuterium was supposed to play the role of firewood, a mixture of deuterium and tritium - a glass of gasoline, and an atomic bomb - a match. This scheme was called a “pipe” - a kind of cigar with an atomic lighter at one end. Soviet physicists began to develop the hydrogen bomb using the same scheme.
However, mathematician Stanislav Ulam, using an ordinary slide rule, proved to Teller that the occurrence of a fusion reaction of pure deuterium in a “super” is hardly possible, and the mixture would require such an amount of tritium that to produce it it would be necessary to practically freeze the production of weapons-grade plutonium in the United States.
Puff with sugar
In mid-1946, Teller proposed another hydrogen bomb design - an “alarm clock”. It consisted of alternating spherical layers of uranium, deuterium and tritium. During the nuclear explosion of the central charge of plutonium, the necessary pressure and temperature were created for the start of a thermonuclear reaction in other layers of the bomb. However, the “alarm clock” required a high-power atomic initiator, and the United States (as well as the USSR) had problems producing weapons-grade uranium and plutonium.
In the fall of 1948, Andrei Sakharov came to a similar scheme. In the Soviet Union, the design was called “sloyka”. For the USSR, which did not have time to produce weapons-grade uranium-235 and plutonium-239 in sufficient quantities, Sakharov’s puff paste was a panacea. And that's why.
In a conventional atomic bomb, natural uranium-238 is not only useless (the neutron energy during decay is not enough to initiate fission), but also harmful because it eagerly absorbs secondary neutrons, slowing down the chain reaction. Therefore, 90% of weapons-grade uranium consists of the isotope uranium-235. However, neutrons resulting from thermonuclear fusion are 10 times more energetic than fission neutrons, and natural uranium-238 irradiated with such neutrons begins to fission excellently. The new bomb made it possible to use uranium-238, which had previously been considered a waste product, as an explosive.
The highlight of Sakharov’s “puff pastry” was also the use of a white light crystalline substance - lithium deuteride 6 LiD - instead of acutely deficient tritium.
As mentioned above, a mixture of deuterium and tritium ignites much more easily than pure deuterium. However, this is where the advantages of tritium end, and only disadvantages remain: in good condition tritium is a gas, which causes storage difficulties; tritium is radioactive and decays into stable helium-3, which actively consumes much-needed fast neutrons, limiting the bomb's shelf life to a few months.
Non-radioactive lithium deutride, when irradiated with slow fission neutrons - the consequences of an explosion of an atomic fuse - turns into tritium. Thus, the radiation from the primary atomic explosion instantly produces a sufficient amount of tritium for a further thermonuclear reaction, and deuterium is initially present in lithium deutride.
It was just such a bomb, RDS-6s, that was successfully tested on August 12, 1953 at the tower of the Semipalatinsk test site. The power of the explosion was 400 kilotons, and there is still debate over whether it was a real thermonuclear explosion or a super-powerful atomic one. After all, the thermonuclear fusion reaction in Sakharov’s puff paste accounted for no more than 20% of the total charge power. The main contribution to the explosion was made by the decay reaction of uranium-238 irradiated with fast neutrons, thanks to which the RDS-6s ushered in the era of the so-called “dirty” bombs.
The fact is that the main radioactive contamination comes from decay products (in particular, strontium-90 and cesium-137). Essentially, Sakharov’s “puff pastry” was a giant atomic bomb, only slightly enhanced thermonuclear reaction. It is no coincidence that just one “puff pastry” explosion produced 82% of strontium-90 and 75% of cesium-137, which entered the atmosphere over the entire history of the Semipalatinsk test site.
American bombs
However, it was the Americans who were the first to detonate the hydrogen bomb. November 1, 1952 at Elugelab Atoll in Pacific Ocean The Mike thermonuclear device with a yield of 10 megatons was successfully tested. It would be hard to call a 74-ton American device a bomb. “Mike” was a bulky device the size of a two-story house, filled with liquid deuterium at a temperature close to absolute zero (Sakharov’s “puff pastry” was a completely transportable product). However, the highlight of “Mike” was not its size, but the ingenious principle of compressing thermonuclear explosives.
Let us recall that the main idea of a hydrogen bomb is to create conditions for fusion (ultra-high pressure and temperature) through a nuclear explosion. In the “puff” scheme, the nuclear charge is located in the center, and therefore it does not so much compress the deuterium as scatter it outward - increasing the amount of thermonuclear explosive does not lead to an increase in power - it simply does not have time to detonate. This is precisely what limits the maximum power of this scheme - the most powerful “puff” in the world, the Orange Herald, blown up by the British on May 31, 1957, yielded only 720 kilotons.
It would be ideal if we could make the atomic fuse explode inside, compressing the thermonuclear explosive. But how to do that? Edward Teller put forward a brilliant idea: to compress thermonuclear fuel not with mechanical energy and neutron flux, but with the radiation of the primary atomic fuse.
In Teller's new design, the initiating atomic unit was separated from the thermonuclear unit. When the atomic charge was triggered, X-ray radiation preceded the shock wave and spread along the walls of the cylindrical body, evaporating and turning the polyethylene inner lining of the bomb body into plasma. The plasma, in turn, re-emited softer X-rays, which were absorbed by the outer layers of the inner cylinder of uranium-238 - the “pusher”. The layers began to evaporate explosively (this phenomenon is called ablation). Hot uranium plasma can be compared to the jets of a super-powerful rocket engine, the thrust of which is directed into the cylinder with deuterium. The uranium cylinder collapsed, the pressure and temperature of deuterium reached critical level. The same pressure compressed the central plutonium tube to a critical mass, and it detonated. The explosion of the plutonium fuse pressed on the deuterium from the inside, further compressing and heating the thermonuclear explosive, which detonated. An intense stream of neutrons splits the uranium-238 nuclei in the “pusher”, causing a secondary decay reaction. All this managed to happen before the moment when the blast wave from the primary nuclear explosion reached the thermonuclear unit. The calculation of all these events, occurring in billionths of a second, required the brainpower of the strongest mathematicians on the planet. The creators of “Mike” experienced not horror from the 10-megaton explosion, but indescribable delight - they managed not only to understand the processes that in the real world occur only in the cores of stars, but also to experimentally test their theories by setting up their own small star on Earth.
Bravo
Having surpassed the Russians in the beauty of the design, the Americans were unable to make their device compact: they used liquid supercooled deuterium instead of Sakharov’s powdered lithium deuteride. In Los Alamos they reacted to Sakharov’s “puff pastry” with a bit of envy: “instead of a huge cow with a bucket of raw milk, the Russians use a bag of powdered milk.” However, both sides failed to hide secrets from each other. On March 1, 1954, near the Bikini Atoll, the Americans tested a 15-megaton bomb “Bravo” using lithium deuteride, and on November 22, 1955, the first Soviet two-stage thermonuclear bomb RDS-37 with a power of 1.7 megatons exploded over the Semipalatinsk test site, demolishing almost half of the test site. Since then, the design of the thermonuclear bomb has undergone minor changes (for example, a uranium shield appeared between the initiating bomb and the main charge) and has become canonical. And there are no more large-scale mysteries of nature left in the world that could be solved with such a spectacular experiment. Perhaps the birth of a supernova.
| A little theory There are 4 reactions in a thermonuclear bomb, and they proceed very quickly. The first two reactions serve as a source of material for the third and fourth, which at the temperatures of a thermonuclear explosion proceed 30-100 times faster and give a greater energy yield. Therefore, the resulting helium-3 and tritium are immediately consumed. The nuclei of atoms are positively charged and therefore repel each other. In order for them to react, they need to be pushed head-on, overcoming the electrical repulsion. This is only possible if they move at high speed. The speed of atoms is directly related to the temperature, which should reach 50 million degrees! But heating deuterium to such a temperature is not enough; it must also be kept from scattering by the monstrous pressure of about a billion atmospheres! In nature, such temperatures at such densities are found only in the core of stars. |
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