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textbook:nrctextbook:chapter4 [2025-03-03 12:28] Merja Herzig |
textbook:nrctextbook:chapter4 [2025-08-28 14:18] (current) Merja Herzig |
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| ====== 4. Radionuclides ====== | ====== 4. Radionuclides ====== | ||
| Chapter 4 from //BASICS OF NUCLEAR PHYSICS AND OF RADIATION DETECTION AND MEASUREMENT – An open-access textbook for nuclear and radiochemistry students// by Jukka Lehto | Chapter 4 from //BASICS OF NUCLEAR PHYSICS AND OF RADIATION DETECTION AND MEASUREMENT – An open-access textbook for nuclear and radiochemistry students// by Jukka Lehto | ||
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| ===== 4.1. Primordial radionuclides ===== | ===== 4.1. Primordial radionuclides ===== | ||
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| Primordial (primary) radionuclides, | Primordial (primary) radionuclides, | ||
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| + | * Parent nuclides of natural [[textbook: | ||
| + | * Individual radionuclides of elements lighter than bismuth ([[textbook: | ||
| - | * Parent nuclides of natural decay chains, < | + | {{anchor: |
| - | * Individual radionuclides of elements lighter than bismuth (Table IV.I.) | + | {{anchor: |
| Table IV.I Lighter primordial naturally occurring radionuclides | Table IV.I Lighter primordial naturally occurring radionuclides | ||
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| ^Nuclide ^Isotopic abundance (%) ^Decay mode ^Half-life (a)^ | ^Nuclide ^Isotopic abundance (%) ^Decay mode ^Half-life (a)^ | ||
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| - | Many of these very long-lived radionuclides were earlier considered as stable ones but as the measurement techniques have developed, their radioactive nature has become apparent. The isotopic abundances to these radionuclides are also presented, as in Table IV.I, because their fractions of the total element do not change in human observation time period. Considering radiation dose to humans the most important of these radionuclides is the < | + | Many of these very long-lived radionuclides were earlier considered as stable ones but as the measurement techniques have developed, their radioactive nature has become apparent. The isotopic abundances to these radionuclides are also presented, as in [[textbook: |
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| ===== 4.2. Secondary natural radionuclides - decay chains ===== | ===== 4.2. Secondary natural radionuclides - decay chains ===== | ||
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| - | The three primordial radionuclides < | + | The three [[textbook: |
| - | radionuclides of twelve elements. The half-life of < | + | |
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| - | {{: | + | Figure IV.1. The uranium decay chain, A = 4n+2. |
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| - | Figure IV.1. The uranium decay chain, A = 4n+2 (http:// | + | |
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| - | From < | + | From < |
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| + | {{: | ||
| - | {{: | + | Figure IV.2. The actinium decay chain, A = 4n+3. |
| - | Figure IV.2. The actinium decay chain, A = 4n+3 | ||
| - | (http:// | ||
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| - | The third decay chain starts from < | + | The third decay chain starts from < |
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| + | {{: | ||
| - | {{: | + | Figure IV.3. The thorium decay chain, A = 4n. |
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| - | Figure IV.3. The thorium decay chain, A = 4n (http:// | + | |
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| - | The uranium series has some important radionuclides with respect to radiation dose to humans. Most important of these is < | + | The uranium series has some important radionuclides with respect to radiation dose to humans. Most important of these is < |
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| ===== 4.3. Cosmogenic radionuclides ===== | ===== 4.3. Cosmogenic radionuclides ===== | ||
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| - | Cosmogenic radionuclides generate in the atmosphere through nuclear reactions induced by cosmic radiation. The main components of cosmic radiation are highly energetic protons and alpha particles. In the primary reactions of particles with atoms of the atmosphere, neutrons are also formed and these can induce further nuclear reactions. Altogether about forty cosmogenic radionuclides are known and some of them are listed in Table IV.II. | + | Cosmogenic radionuclides generate in the atmosphere through |
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| Table IV.II. Important cosmogenic radionuclides. | Table IV.II. Important cosmogenic radionuclides. | ||
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| ===== 4.4. Artificial radionuclides ===== | ===== 4.4. Artificial radionuclides ===== | ||
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| - | * in nuclear weapon production and explosions | + | * in [[textbook: |
| - | * in nuclear power production | + | * in [[textbook: |
| - | * in production of radionuclides with reactors and accelerators | + | * in production of radionuclides with [[textbook: |
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| - | In nuclear weapon production, a source of radionuclides is plutonium production, which is done by irradiating < | + | In **//nuclear weapon production//**, a source of radionuclides is plutonium production, which is done by irradiating < |
| formed in plutonium production are essentially the same as in nuclear explosions and in nuclear power reactors. After radiochemical separation of plutonium for weapons material the rest, the high-active waste solution, contains the fission products and other radionuclides than Pu and U. These waste solutions are stored in tanks in the USA and they still wait to be treated before final disposal. In the former Soviet Union, only part of the waste solutions are in tanks while a large fraction was discharged into the environment at the Majak site, first to Techa river and later to Karachai lake. This has resulted in a huge contamination of the area. In nuclear weapons production, there has been two major accidents leading to large environmental contamination. The first occurred in 1957 in Sellafield in the UK where a plutonium production reactor caught fire and released large amounts of radioactivity, | formed in plutonium production are essentially the same as in nuclear explosions and in nuclear power reactors. After radiochemical separation of plutonium for weapons material the rest, the high-active waste solution, contains the fission products and other radionuclides than Pu and U. These waste solutions are stored in tanks in the USA and they still wait to be treated before final disposal. In the former Soviet Union, only part of the waste solutions are in tanks while a large fraction was discharged into the environment at the Majak site, first to Techa river and later to Karachai lake. This has resulted in a huge contamination of the area. In nuclear weapons production, there has been two major accidents leading to large environmental contamination. The first occurred in 1957 in Sellafield in the UK where a plutonium production reactor caught fire and released large amounts of radioactivity, | ||
| radionuclides. | radionuclides. | ||
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| - | The 99.99% of the radioactivity created in nuclear power production is in spent nuclear fuel of which 96% is uranium dioxide, 3% is fission products and 1% is transuranic elements, mainly plutonium. Spent nuclear fuel will be disposed of either after reprocessing or as such into geological formations. In reprocessing the nuclear fuel is dissolved in nitric acid and uranium and plutonium is separated for further use as a fuel while the rest, fission products and minor actinides, remain in the | + | The 99.99% of the radioactivity created in //**nuclear power production**// is in spent nuclear fuel of which 96% is uranium dioxide, 3% is fission products and 1% is transuranic elements, mainly plutonium. Spent nuclear fuel will be disposed of either after reprocessing or as such into geological formations. In reprocessing the nuclear fuel is dissolved in nitric acid and uranium and plutonium is separated for further use as a fuel while the rest, fission products and minor actinides, remain in the |
| high-active waste solution which is vitrified for final disposal. In addition to //fission products// (< | high-active waste solution which is vitrified for final disposal. In addition to //fission products// (< | ||
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| There have been, however, three major accidents in nuclear power plants resulting in a large release of radionuclides into the environment. The first one occurred in 1979 in Harrisburg, USA, but only noble gases and other gaseous radionuclides were released from the damaged reactor and no long-term contamination of the surrounding area took place. The second and the largest accident took place in Chernobyl, Ukraine, where a power reactor exploded and caught fire in 1986. This accident caused a severe environmental contamination, | There have been, however, three major accidents in nuclear power plants resulting in a large release of radionuclides into the environment. The first one occurred in 1979 in Harrisburg, USA, but only noble gases and other gaseous radionuclides were released from the damaged reactor and no long-term contamination of the surrounding area took place. The second and the largest accident took place in Chernobyl, Ukraine, where a power reactor exploded and caught fire in 1986. This accident caused a severe environmental contamination, | ||
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| - | A wide range of radionuclides for research and medical use are being produced in reactors and accelerators. After use, they are mainly either aged or released into the environment. Some of the most important radionuclides used in medical and biosciences and in clinical use are listed in Table IV.III. | + | A wide range of radionuclides for research and medical use are being produced in [[textbook: |
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textbook/nrctextbook/chapter4.1741001305.txt.gz · Last modified: 2025-03-03 12:28 by Merja Herzig