(β −)
235Np()
239 Pu()
Unlike the other, most common isotope of uranium, 238 U, a self-sustaining nuclear chain reaction is possible in 235 U. Therefore, this isotope is used as a fuel in nuclear reactors, as well as in nuclear weapons.
Formation and decay
Uranium-235 is formed as a result of the following decays:
The decay of uranium-235 occurs in the following ways:
Forced division
About 300 isotopes of various elements were found in the fission products of uranium-235: from =30 (zinc) to Z=64 (gadolinium). The curve of the dependence of the relative yield of isotopes formed upon irradiation of uranium-235 with slow neutrons on the mass number is symmetrical and resembles the letter "M" in shape. The two pronounced maxima of this curve correspond to mass numbers 95 and 134, while the minimum falls within the range of mass numbers from 110 to 125. Thus, the fission of uranium into fragments of equal mass (with mass numbers 115-119) occurs with a lower probability than asymmetric fission. such a tendency is observed in all fissile isotopes and is not associated with any individual properties of nuclei or particles, but is inherent in the very mechanism of nuclear fission. However, the asymmetry decreases with increasing excitation energy of the fissile nucleus, and at a neutron energy of more than 100 MeV, the mass distribution of fission fragments has one maximum corresponding to symmetric fission of the nucleus. The fragments formed during the fission of the uranium nucleus, in turn, are radioactive, and undergo a chain of β - decays, in which additional energy is gradually released over a long time. The average energy released during the decay of one uranium-235 nucleus, taking into account the decay of fragments, is approximately 202.5 MeV = 3.244 10 −11 J, or 19.54 TJ / mol = 83.14 TJ / kg.
Nuclear fission is just one of the many processes that are possible during the interaction of neutrons with nuclei; it is he who underlies the operation of any nuclear reactor.
Nuclear chain reaction
During the decay of one 235 U nucleus, from 1 to 8 (on average - 2.416) free neutrons are usually emitted. Each neutron produced during the decay of the 235 U nucleus, subject to interaction with another 235 U nucleus, can cause a new decay event, this phenomenon is called nuclear fission chain reaction.
Hypothetically, the number of neutrons of the second generation (after the second stage of nuclear decay) can exceed 3² = 9. With each subsequent stage of the fission reaction, the number of neutrons produced can grow like an avalanche. Under real conditions, free neutrons may not generate a new fission event, leaving the sample before the capture of 235 U, or being captured both by the 235 U isotope itself with its transformation into 236 U, and by other materials (for example, 238 U, or by the resulting nuclear fission fragments, such as 149 Sm or 135 Xe).
In real conditions, reaching the critical state of uranium is not so easy, since a number of factors affect the course of the reaction. For example, natural uranium consists of only 0.72% 235 U, 99.2745% is 238 U, which absorbs neutrons produced during the fission of 235 U nuclei. This leads to the fact that in natural uranium, at present, the fission chain reaction is very fades quickly. There are several main ways to carry out an undamped fission chain reaction:
- Increase the volume of the sample (for uranium extracted from the ore, it is possible to achieve a critical mass due to an increase in volume);
- Carry out isotope separation by increasing the concentration of 235 U in the sample;
- Reduce the loss of free neutrons through the surface of the sample by using various types of reflectors;
- Use a neutron moderator to increase the concentration of thermal neutrons.
Isomers
- Excess mass: 40920.6(1.8) keV
- Excitation energy: 76.5(4) eV
- Half-life: 26 min
- Spin and parity of the nucleus: 1/2 +
The decay of the isomeric state is carried out by isomeric transition to the ground state.
Application
- Uranium-235 is used as fuel for nuclear reactors in which managed fission nuclear chain reaction;
- Highly enriched uranium is used to create nuclear weapons. In this case, to release a large amount of energy (explosion) is used uncontrollable chain nuclear reaction.
see also
Write a review on the article "Uranium-235"
Notes
- G.Audi, A.H. Wapstra, and C. Thibault (2003). "". Nuclear Physics A 729 : 337-676. DOI:10.1016/j.nuclphysa.2003.11.003 . Bibcode :.
- G. Audi, O. Bersillon, J. Blachot and A. H. Wapstra (2003). "". Nuclear Physics A 729 : 3–128. DOI:10.1016/j.nuclphysa.2003.11.001 . Bibcode :.
- Hoffman K.- 2nd ed. erased - L.: Chemistry, 1987. - S. 130. - 232 p. - 50,000 copies.
- Fialkov Yu. Ya. The use of isotopes in chemistry and the chemical industry. - Kyiv: Tehnika, 1975. - S. 87. - 240 p. - 2,000 copies.
- . Kaye & Laby Online. .
- Bartolomey G. G., Baibakov V. D., Alkhutov M. S., Bat G. A. Fundamentals of the theory and methods for calculating nuclear power reactors. - M .: Energoatomizdat, 1982. - S. 512.
An excerpt characterizing Uranium-235
Miloradovich, who said that he did not want to know anything about the economic affairs of the detachment, which could never be found when it was needed, "chevalier sans peur et sans reproche" ["a knight without fear and reproach"], as he himself called himself , and a hunter for conversations with the French, sent truce deputies, demanding surrender, and wasted time and did not do what he was ordered to.“I give you guys this column,” he said, driving up to the troops and pointing to the French cavalrymen. And the cavalrymen on thin, skinned, barely moving horses, urging them on with spurs and sabers, trotted, after strong tensions, drove up to the donated column, that is, to the crowd of frostbitten, stiff and hungry Frenchmen; and the donated column threw down its weapons and surrendered, which it had long wanted to do.
Near Krasnoye they took twenty-six thousand prisoners, hundreds of cannons, some kind of stick, which they called the marshal's baton, and argued about who distinguished themselves there, and were pleased with this, but very much regretted that they had not taken Napoleon or at least some hero, marshal, and reproached each other for this, and especially Kutuzov.
These people, carried away by their passions, were blind executors of only the saddest law of necessity; but they considered themselves heroes and imagined that what they did was the most worthy and noble deed. They accused Kutuzov and said that from the very beginning of the campaign he prevented them from defeating Napoleon, that he only thought about satisfying his passions and did not want to leave the Linen Factories, because he was calm there; that he stopped the movement near Krasnoe only because, having learned about the presence of Napoleon, he was completely lost; that it can be assumed that he is in a conspiracy with Napoleon, that he is bribed by him, [Wilson's Notes. (Note by L.N. Tolstoy.)], etc., etc.
Not only did contemporaries, carried away by passions, say this, - posterity and history recognized Napoleon as grand, and Kutuzov: foreigners - a cunning, depraved, weak court old man; Russians - something indefinite - some kind of doll, useful only in their Russian name ...
In the 12th and 13th years, Kutuzov was directly accused of mistakes. The sovereign was dissatisfied with him. And in a story recently written by the highest command, it is said that Kutuzov was a cunning court liar who was afraid of the name of Napoleon and, with his mistakes near Krasnoye and near the Berezina, deprived the Russian troops of glory - a complete victory over the French. [History of 1812 by Bogdanovich: characterization of Kutuzov and discussion of the unsatisfactory results of the Krasnensky battles. (Note by L.N. Tolstoy.)]
Such is the fate not of great people, not grand homme, whom the Russian mind does not recognize, but the fate of those rare, always lonely people who, comprehending the will of Providence, subordinate their personal will to it. The hatred and contempt of the crowd punish these people for the enlightenment of higher laws.
For Russian historians - it is strange and terrible to say - Napoleon is the most insignificant tool of history - never and nowhere, even in exile, who did not show human dignity - Napoleon is an object of admiration and delight; he grand. Kutuzov, the man who, from the beginning to the end of his activity in 1812, from Borodin to Vilna, never betraying himself with a single action, not a word, is an extraordinary example of self-denial and awareness in the present of the future meaning of an event, - Kutuzov seems to them something indefinite and pathetic, and, speaking of Kutuzov and the 12th year, they always seem to be a little ashamed.
Meanwhile, it is difficult to imagine a historical person whose activity would be so invariably and constantly directed towards the same goal. It is difficult to imagine a goal more worthy and more in line with the will of the whole people. It is even more difficult to find another example in history where the goal set by a historical person would be so completely achieved as the goal towards which Kutuzov’s entire activity was directed in 1812.
Kutuzov never talked about the forty centuries that look from the pyramids, about the sacrifices that he brings to the fatherland, about what he intends to do or has done: he did not say anything at all about himself, did not play any role, he always seemed the most simple and ordinary man and said the most simple and ordinary things. He wrote letters to his daughters and m me Stael, read novels, loved the company of beautiful women, joked with generals, officers and soldiers, and never contradicted those people who wanted to prove something to him. When Count Rostopchin on the Yauzsky Bridge galloped up to Kutuzov with personal reproaches about who was to blame for the death of Moscow, and said: “How did you promise not to leave Moscow without giving a battle?” - Kutuzov answered: "I will not leave Moscow without a fight," despite the fact that Moscow had already been abandoned. When Arakcheev, who came to him from the sovereign, said that Yermolov should be appointed head of artillery, Kutuzov replied: “Yes, I just said it myself,” although he said something completely different in a minute. What did it matter to him, who alone then understood the whole enormous meaning of the event, among the stupid crowd that surrounded him, what did he care about whether Count Rostopchin would attribute the disaster of the capital to himself or to him? Even less could he be interested in who would be appointed chief of artillery.
Not only in these cases, but incessantly this old man, who by experience of life had reached the conviction that the thoughts and words that serve as their expression are not the essence of people's engines, spoke words that were completely meaningless - the first that came to his mind.
But this same man, who so neglected his words, never once in all his activity said a single word that would not be in accordance with the sole goal towards which he was going during the whole war. Obviously, involuntarily, with a heavy certainty that they would not understand him, he repeatedly expressed his opinion in the most diverse circumstances. Starting from the battle of Borodino, from which his discord with those around him began, he alone said that the battle of Borodino was a victory, and he repeated this verbally, and in reports, and reports until his death. He alone said that the loss of Moscow is not the loss of Russia. In response to Loriston's proposal for peace, he replied that there could be no peace, because such was the will of the people; he alone, during the retreat of the French, said that all our maneuvers were not needed, that everything would become better by itself than we wished, that the enemy should be given a golden bridge, that neither Tarutino, nor Vyazemsky, nor Krasnensky battles were needed, what with what someday you need to come to the border, that for ten Frenchmen he will not give up one Russian.
And he is alone, this court man, as he is portrayed to us, a man who lies to Arakcheev in order to please the sovereign - he alone, this court man, in Vilna, thus deserving the sovereign's disfavor, says that further war abroad is harmful and useless.
But words alone would not prove that he then understood the significance of the event. His actions - all without the slightest retreat, all were directed towards the same goal, expressed in three actions: 1) strain all their forces to clash with the French, 2) defeat them and 3) expel them from Russia, facilitating, as far as possible, disasters of the people and troops.
He, that procrastinator Kutuzov, whose motto is patience and time, the enemy of decisive action, he gives the battle of Borodino, dressing the preparations for it in unparalleled solemnity. He, that Kutuzov, who in the battle of Austerlitz, before it began, says that it will be lost, in Borodino, despite the assurances of the generals that the battle is lost, despite the unheard-of example in history that after the battle won, the army must retreat , he alone, in opposition to everyone, claims until his death that the battle of Borodino is a victory. He alone during the entire retreat insists on not giving battles, which are now useless, not starting a new war and not crossing the borders of Russia.
Now it is easy to understand the meaning of an event, unless we apply to the activity of masses of goals that were in the head of a dozen people, since the whole event with its consequences lies before us.
But how then could this old man, alone, contrary to the opinion of all, guess, so correctly guessed then the meaning of the popular meaning of the event, that he never betrayed him in all his activity?
The source of this extraordinary power of insight into the meaning of occurring phenomena lay in that popular feeling, which he carried within himself in all its purity and strength.
Only the recognition of this feeling in him made the people, in such strange ways, from an old man who was in disfavor, choose him against the will of the tsar to be representatives of the people's war. And only this feeling put him on that highest human height, from which he, the commander-in-chief, directed all his forces not to kill and exterminate people, but to save and pity them.
Uranium-235(English uranium-235), historical name actinouranium(lat. Actin Uranium, indicated by the symbol AcU) is a radioactive nuclide of the chemical element uranium with atomic number 92 and mass number 235. The isotopic abundance of uranium-235 in nature is 0.7200 (51)%. It is the ancestor of the radioactive family 4n + 3, called the actinium series. Opened in 1935 by Arthur Dempster. Arthur Jeffrey Dempster.
Unlike the other, most common uranium isotope 238U, a self-sustaining nuclear chain reaction is possible in 235U. Therefore, this isotope is used as fuel in nuclear reactors, as well as in nuclear weapons.
The activity of one gram of this nuclide is approximately 80 kBq.
- 1 Formation and breakup
- 2 Forced division
- 2.1 Nuclear chain reaction
- 3 Isomers
- 4 Application
- 5 See also
- 6 Notes
Formation and decay
Uranium-235 is formed as a result of the following decays:
- β-decay of the nuclide 235Pa (half-life is 24.44(11) min):
- K-capture by nuclide 235Np (half-life is 396.1(12) days):
- α-decay of the nuclide 239Pu (half-life is 2.411(3) 104 years):
The decay of uranium-235 occurs in the following ways:
- α-decay in 231Th (probability 100%, decay energy 4678.3(7) keV):
- Spontaneous fission (probability 7(2) 10−9%);
- Cluster decay with the formation of nuclides 20Ne, 25Ne and 28Mg (the probabilities are respectively 8(4) 10−10%, 8 10−10%, 8 10−10%):
Forced division
Main article: Nuclear fission Yield curve of uranium-235 fission products for various energies of fissile neutrons.In the early 1930s Enrico Fermi carried out the irradiation of uranium with neutrons, with the aim of obtaining transuranium elements in this way. But in 1939, O. Hahn and F. Strassmann were able to show that when a neutron is absorbed by a uranium nucleus, a forced fission reaction occurs. As a rule, the nucleus is divided into two fragments, with the release of 2-3 neutrons (see diagram).
About 300 isotopes of various elements were found in the fission products of uranium-235: from Z=30 (zinc) to Z=64 (gadolinium). The curve of the dependence of the relative yield of isotopes formed upon irradiation of uranium-235 with slow neutrons on the mass number is symmetrical and resembles the letter "M" in shape. The two pronounced maxima of this curve correspond to mass numbers 95 and 134, and the minimum falls on the range of mass numbers from 110 to 125. Thus, the fission of uranium into fragments of equal mass (with mass numbers 115-119) occurs with a lower probability than asymmetric fission, such a tendency is observed in all fissile isotopes and is not associated with any individual properties of nuclei or particles, but is inherent in the very mechanism of nuclear fission. However, the asymmetry decreases with increasing excitation energy of the fissile nucleus, and at a neutron energy of more than 100 MeV, the mass distribution of fission fragments has one maximum corresponding to symmetric fission of the nucleus.
One of the options for forced fission of uranium-235 after the absorption of a neutron (scheme)
The fragments formed during the fission of the uranium nucleus, in turn, are radioactive, and undergo a chain of β-decays, in which additional energy is gradually released over a long time. The average energy released during the decay of one uranium-235 nucleus, taking into account the decay of fragments, is approximately 202.5 MeV = 3.244 10−11 J, or 19.54 TJ/mol = 83.14 TJ/kg.
Nuclear fission is just one of the many processes that are possible during the interaction of neutrons with nuclei; it is he who underlies the operation of any nuclear reactor.
Nuclear chain reaction
Main article: Nuclear chain reactionThe decay of one 235U nucleus usually emits from 1 to 8 (2.5 on average) free neutrons. Each neutron formed during the decay of the 235U nucleus, subject to interaction with another 235U nucleus, can cause a new decay event, this phenomenon is called a nuclear fission chain reaction.
Hypothetically, the number of neutrons of the second generation (after the second stage of nuclear decay) can exceed 3² = 9. With each subsequent stage of the fission reaction, the number of neutrons produced can grow like an avalanche. In real conditions, free neutrons may not generate a new fission event, leaving the sample before the capture of 235U, or being captured both by the 235U isotope itself with its transformation into 236U, and by other materials (for example, 238U, or by the resulting nuclear fission fragments, such as 149Sm or 135Xe ).
If, on average, each fission generates another new fission, then the reaction becomes self-sustaining; this condition is called critical. (see also neutron multiplication factor)
In real conditions, reaching the critical state of uranium is not so easy, since a number of factors affect the course of the reaction. For example, natural uranium consists of only 0.72% 235U, 99.2745% is 238U, which absorbs neutrons produced during the fission of 235U nuclei. This leads to the fact that in natural uranium at present the fission chain reaction decays very quickly. An undamped fission chain reaction can be carried out in several main ways:
- Increase the volume of the sample (for uranium extracted from the ore, it is possible to achieve a critical mass due to an increase in volume);
- Carry out isotope separation by increasing the concentration of 235U in the sample;
- Reduce the loss of free neutrons through the surface of the sample by using various types of reflectors;
- Use a substance - neutron moderator to increase the concentration of thermal neutrons.
Isomers
A single 235Um isomer is known with the following characteristics:
- Excess mass: 40920.6(1.8) keV
- Excitation energy: 76.5(4) eV
- Half-life: 26 min
- Spin and parity of the nucleus: 1/2+
The decay of the isomeric state is carried out by isomeric transition to the ground state.
Application
- Uranium-235 is used as fuel for nuclear reactors in which a controlled fission chain reaction is carried out;
- Uranium with a high degree of enrichment is used to create nuclear weapons. In this case, an uncontrolled nuclear chain reaction is used to release a large amount of energy (an explosion).
see also
- Isotopes of uranium
- Isotope separation
Notes
- 1 2 3 4 5 G.Audi, A.H. Wapstra, and C. Thibault (2003). "The AME2003 atomic mass evaluation (II). Tables, graphs, and references. Nuclear Physics A 729 : 337-676. DOI:10.1016/j.nuclphysa.2003.11.003. Bibcode: 2003NuPhA.729..337A.
- 1 2 3 4 5 6 7 8 9 10 11 12 G. Audi, O. Bersillon, J. Blachot and A. H. Wapstra (2003). "The NUBASE evaluation of nuclear and decay properties". Nuclear Physics A 729 : 3–128. DOI:10.1016/j.nuclphysa.2003.11.001. Bibcode: 2003NuPhA.729....3A.
- Hoffman K. Is it possible to make gold? - 2nd ed. erased - L.: Chemistry, 1987. - S. 130. - 232 p. - 50,000 copies.
- Today in science history
- 1 2 3 Fialkov Yu. Ya. Application of isotopes in chemistry and chemical industry. - Kyiv: Tehnika, 1975. - S. 87. - 240 p. - 2,000 copies.
- Table of Physical and Chemical Constants, Sec 4.7.1: Nuclear Fission. Kaye & Laby Online. Archived from the original on April 8, 2012.
- Bartolomey GG, Baibakov VD, Alkhutov MS, Bat' GA Fundamentals of theory and calculation methods for nuclear power reactors. - M.: Energoatomizdat, 1982. - S. 512.
uranium 235 50, uranium 235 75, uranium 235 area, uranium 235/75r15
Studying the phenomenon of radioactivity, each scientist refers to such an important characteristic as its half-life. As you know, it says that every second in the world there is a decay of atoms, while the quantitative characteristics of these processes are directly related to the number of atoms present. If in a certain period of time half of the total number of atoms available will decay, then the decay of ½ of the remaining atoms will require the same amount of time. It is this time period that is called the half-life. For different elements, it is different - from thousandths of a millisecond to billions of years, as, for example, in the case when it comes to the half-life of uranium.
Uranium, as the heaviest of all the naturally existing elements on Earth, is generally the most excellent object for studying the process of radioactivity. This element was discovered back in 1789 by the German scientist M. Klaproth, who named it in honor of the recently discovered planet Uranus. The fact that uranium is radioactive was established quite by accident at the end of the 19th century by the French chemist A. Becquerel.
Uranus is calculated using the same formula as the analogous periods of other radioactive elements:
T_(1/2) = au ln 2 = frac(ln 2)(lambda),
where "au" is the average lifetime of an atom, "lambda" is the main decay constant. Since ln 2 is about 0.7, the half-life is only 30% shorter on average than the total lifetime of an atom.
Despite the fact that today scientists know 14 isotopes of uranium, only three of them occur in nature: uranium-234, uranium-235 and uranium-238. uranium is different: so for U-234 it is "only" 270 thousand years, and the half-life of uranium-238 exceeds 4.5 billion. The half-life of uranium-235 is in the "golden mean" - 710 million years.
It should be noted that the radioactivity of uranium in natural conditions is quite high and allows, for example, photographic plates to be illuminated for only an hour. At the same time, it is worth noting that, of all uranium isotopes, only U-235 is suitable for making stuffing for uranium. here is minimal.
The half-life of uranium-238 is well over 4 billion years, but it is now actively used in the nuclear industry. So, in order to start a chain reaction for the fission of heavy nuclei of this element, a significant amount of neutron energy is needed. Uranium-238 is used as protection in fission and fusion apparatuses. However, most of the uranium-238 mined is used to synthesize plutonium, which is used in nuclear weapons.
Scientists use the half-life of uranium to calculate the age of individual minerals and celestial bodies as a whole. The uranium clock is a fairly universal mechanism for such calculations. At the same time, in order to calculate the age more or less accurately, it is necessary to know not only the amount of uranium in certain rocks, but also the ratio of uranium and lead as the final product into which uranium nuclei are converted.
There is another way to calculate rocks and minerals, it is associated with the so-called spontaneous. As you know, as a result of spontaneous fission of uranium in natural conditions, its particles bombard nearby substances with colossal force, leaving behind special traces - tracks.
It is by the number of these tracks, knowing at the same time the half-life of uranium, that scientists draw a conclusion about the age of a particular solid body - be it an ancient rock or a relatively “young” vase. The thing is that the age of an object is directly proportional to the quantitative index of uranium atoms, the nuclei of which bombarded it.
Plutonium is a man-made element. Before the atomic era, there were only its "traces" in nature - several tens of kilograms in the entire thickness of the earth's crust. Now - hundreds of tons, and not in the entire earth's crust, but in bombs and warehouses, plus tons scattered over the surface of the planet.
In just one year, all reactors in the world produce 10,000 tons of SNF, which contains 100 tons of plutonium, that is, each ton of SNF contains ~ 10 kg of plutonium (for comparison, in the bomb dropped on Nagasaki, it was only 6.2 kg ).
Although reactor-grade plutonium, separated during the processing of spent nuclear fuel, does not have a weapon-grade quality, it is still possible to make a bomb out of it. The world is already full of separated plutonium for making bombs. There is a lot of it: in deployed weapons systems, in warheads intended for dismantling, in waste from the cleaning of nuclear weapons complexes, in warehouses at processing plants.
Fissile, that is, weapons, is an isotope - plutonium-239. For its development, in addition to enriched uranium (fuel), unenriched, natural, uranium ("raw material") was placed in a military reactor in the form of metal blocks enclosed in a sealed aluminum shell. During the fission reaction in the reactor core, a large flux of neutrons occurs and uranium blocks are irradiated with these neutrons (hence the term "irradiated uranium" or irradiated nuclear fuel).
When neutrons are captured, the nuclei of uranium atoms turn into plutonium nuclei, therefore, inside the blocks, non-fissile uranium-238 gradually turned into fissile (weapon-grade) plutonium-239. During the holding time in the reactor (3-6 months), several hundred grams of uranium-238 were converted from each ton of natural uranium into plutonium-239.
Uranium is a radioactive metal. In nature, uranium consists of three isotopes: uranium-238, uranium-235 and uranium-234. The highest level of stability is recorded for uranium-238.
| Characteristic | Meaning |
|---|---|
| General information | |
| Name, symbol | Uran-238, 238U |
| Alternative titles | uranium one, UI |
| Neutrons | 146 |
| Protons | 92 |
| Nuclide properties | |
| Atomic mass | 238.0507882(20) a. eat. |
| Excess mass | 47 308.9(19) keV |
| Specific binding energy (per nucleon) | 7570.120(8) keV |
| Isotopic abundance | 99,2745(106) % |
| Half life | 4,468(3) 109 years |
| Decay products | 234Th, 238Pu |
| Parent isotopes | 238Pa (β−) 242Pu(α) |
| Spin and parity of the nucleus | 0+ |
| Decay channel | Decay energy |
| α-decay | 4.2697(29) MeV |
| SF | |
| ββ | 1.1442(12) MeV |
radioactive decay of uranium
Radioactive decay is the process of a sudden change in the composition or internal structure of atomic nuclei, which are characterized by instability. In this case, elementary particles, gamma quanta and/or nuclear fragments are emitted. Radioactive substances contain a radioactive nucleus. The daughter nucleus resulting from radioactive decay can also become radioactive and, after a certain time, undergoes decay. This process continues until a stable nucleus devoid of radioactivity is formed. E. Rutherford experimentally proved in 1899 that uranium salts emit three types of rays:
- α-rays - a stream of positively charged particles
- β-rays - a stream of negatively charged particles
- γ-rays - do not create deviations in the magnetic field.
| Type of radiation | Nuclide | Half life |
|---|---|---|
| Ο | Uranus - 238 U | 4.47 billion years |
| α ↓ | ||
| Ο | Thorium - 234 Th | 24.1 days |
| β ↓ | ||
| Ο | Protactinium - 234 Pa | 1.17 minutes |
| β ↓ | ||
| Ο | Uranium - 234 U | 245,000 years |
| α ↓ | ||
| Ο | Thorium - 230 Th | 8000 years |
| α ↓ | ||
| Ο | Radium - 226 Ra | 1600 years |
| α ↓ | ||
| Ο | Polonium - 218 Po | 3.05 minutes |
| α ↓ | ||
| Ο | Lead - 214 Pb | 26.8 minutes |
| β ↓ | ||
| Ο | Bismuth - 214 Bi | 19.7 minutes |
| β ↓ | ||
| Ο | Polonium - 214 Po | 0.000161 seconds |
| α ↓ | ||
| Ο | Lead - 210 Pb | 22.3 years |
| β ↓ | ||
| Ο | Bismuth - 210 Bi | 5.01 days |
| β ↓ | ||
| Ο | Polonium - 210 Po | 138.4 days |
| α ↓ | ||
| Ο | Lead - 206 Pb | stable |
Radioactivity of uranium
Natural radioactivity is what distinguishes radioactive uranium from other elements. Uranium atoms, regardless of any factors and conditions, gradually change. In this case, invisible rays are emitted. After the transformations that occur with uranium atoms, a different radioactive element is obtained and the process is repeated. He will repeat as many times as necessary to get a non-radioactive element. For example, some chains of transformations have up to 14 stages. In this case, the intermediate element is radium, and the last stage is the formation of lead. This metal is not a radioactive element, so a number of transformations are interrupted. However, it takes several billion years for the complete transformation of uranium into lead.
Radioactive uranium ore often causes poisoning at enterprises involved in the extraction and processing of uranium raw materials. In the human body, uranium is a general cellular poison. It mainly affects the kidneys, but liver and gastrointestinal lesions also occur.
Uranium does not have completely stable isotopes. The longest lifetime is noted for uranium-238. The semi-decay of uranium-238 occurs over 4.4 billion years. A little less than one billion years is the half-decay of uranium-235 - 0.7 billion years. Uranium-238 occupies over 99% of the total volume of natural uranium. Due to its colossal half-life, the radioactivity of this metal is not high, for example, alpha particles cannot penetrate the stratum corneum of human skin. After a series of studies, scientists found that the main source of radiation is not uranium itself, but the radon gas formed by it, as well as its decay products that enter the human body during breathing.
