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

2. RADIOACTIVITY (from Latin radio — radiate the beam and 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.

8. 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 Tritium 12,3 years Strontium-90 28,5 years Caesium-137 30 years Carbon-14 5370 years Iodine -129 17 million years

9. 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.

11. NaturalAnthropogenic Long-lived 235,238,234 U, 232 Th, 40 K, 87 Rb, l52 Sm, l87 Re, 138 La, l 76 Lu и др. Fission- fragment elements 134,137 Cs, 90 Sr, 106 Ru, l4l Ce, l40 La, l47 Nd, 99 Tc, l47 Pm and others Short-lived and medium-lived uranium series: radon and etc. thorium series: thoron and etc. Actinouranium series: actinon and etc. Activation products 54 Fe, 60 Co, 65 Zn, 22 Na, 32 P и т.д. Constantly forming in nature as a result of nuclear reactions with protons, neutrons and other particles of earth and cosmic origin 14 N (n,p) - 14 С (5,8*10 3 years) 6 Li (n) - 3 H (12,3 years) 2 Н (n,у) - 3 Н 2 Н (n,p) - 3 Н 238 U (n,у) - ß - 237 Np- ß - 239 Pu (negligibly small quantities). Spontaneous decay 238 U leads to formation of 90 Sr, 99 Тс, 147 Рm and etc. Elements of nuclear addition reaction Neptunium (Np) Plutonium (Pu) Americium (Am) Curium (Сm) Berkelium (Bk) Californium (Cf) Mendelevium (Md) and etc. Radioactive elements classification

12. Fission-fragment elements Образование осколочных радионуклидов 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.

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

14. 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): 90 Sr, 134 Cs, 137 Cs, 140 La, 131 I, 129 I, 99 Tc, 106 Ru, 141 Ce Activation products– due to interaction neutrons, gamma-quanta and etc. with substance: 56 Fe, 22 Na, 60 Co, 65 Zn, 32 P Transuranuim radioactive elements – chemical elements with atomic number more than uranium-92: 240 Pu, 239 Pu, 239 U, 239 Np, 247 Cm, 241 Am

15. Fission radioactive elements The main most dangerous radioactive elements and their properties element Half life Type of decay Activity Ки/g Emit energy AlphaBetaGamma Krypton-8510,72 years β Iodine-1318,04 days β Iodine-12917million years β Strontium-9028,5 years β Caesium-13730 years β-γβ-γ Lanthanum-138100 billion years β Europium-15213,3 years γ