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Types of radioactivity

Types of radioactivity. Rikhvanov Leonid P., professor, DSc in Geology and Mineralogy Nadeina Luiza V., associate professor, PhD in Philology TOMSK -2015.

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Types of radioactivity

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  1. Types of radioactivity Rikhvanov Leonid P., professor,DSc in Geology and MineralogyNadeina Luiza V., associate professor,PhD in Philology TOMSK -2015

  2. RADIOACTIVITY(from Latin radio — radiate the beamand activus — active), spontaneous transformation unstable atom nuclei in atom nuclei of other elements, conducting by emission of particles or gamma quantum.

  3. There are three types of radioactivity. Gamma rays come from the nucleus of the atom of a radioactive isotope. They are the most energetic and most penetrating of all radiation. Some radiation travel as particles not waves and is also emitted by the radioactive isotope. One is alpha particles that lose energy quickly. A hand or thin piece of paper stops it. Beta particles are high speed electrons that travel close to the speed of light and can penetrate a hand but not concrete.

  4. When an atom undergoes radioactive decay, it emits one or more forms of radiation with sufficient energy to ionize the atoms with which it interacts. Ionizing radiation can consist of high speed subatomic particles ejected from the nucleus or electromagnetic radiation (gamma-rays) emitted by either the nucleus or orbital electrons.

  5. The time in which half the atoms of a particular radioactive nuclide disintegrate. It is called half life. The half-life is a characteristic property of each radioactive isotope. During one half life from 100 atoms of radionuclides only 50 ones remain. Different radionuclides have got various speed of half life. Element Half life Iodine-131 8,04 days Krypton-85 10,72 years Tritium12,3 years Strontium-90 28,5 years Caesium-137 30 years Carbon-14 5370 years Iodine -129 17 million years HALF LIFE

  6. All radioactive elements decompose due to a law of radioactive decay: N = No * е-λt where Nо – number of radioactive atoms in initial time of appearance nuclide (tо); е - base of the natural logarithm (2,718); λ- constant of radioactive decay; it is different for various radionuclides; t - time, passed from (to). Constant of radioactive decay identifies so-called half life (T): Т= ln2/λ = 0,693/λ. Half life Т½ is one of main characteristics of radioactive substance.

  7. Chain of uranium-238 radioactive decay

  8. Radioactive elements classification

  9. Fission-fragment elements Nuclear fission induced by neutrons is the most important source of artificial radionuclides. This process is used to obtain energy in modern nuclear reactors.Nuclear fission gives also the main portion of radionuclides at explosion of nuclear charges. Образование осколочных радионуклидов

  10. β β n,γ n,γ β Transuranium radioactive elements– chemical elements with atomic number more than uranium-92, forming as a result of neutron absorption according to the formula:

  11. All known radioactive elements should be divided into two groups natural and anthropogenic. Natural radioactive elements can be divided into: Fission-fragment (uranium-235 nuclei fission products under thermal neutrons effect): 90Sr,134Cs,137Cs,140La,131I,129I,99Tc,106Ru,141Ce Transuranuim radioactive elements – chemical elements with atomic number more than uranium-92: 240Pu, 239Pu,239U,239Np, 247Cm, 241Am Activation products– due to interaction neutrons, gamma-quanta and etc. with substance: 56Fe, 22Na, 60Co, 65Zn, 32P

  12. Fission radioactive elements

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