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Nuclear Radiation

Introduction to Chemistry for Allied Health Sciences The Nucleus & Radioactivity Kirk Hunter Chemical Technology Department Texas State Technical College Waco. Nuclear Radiation. Nuclear Radiaition. Originates at the nuclei of atoms Some nuclei are unstable. Radioactive nuclides

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Nuclear Radiation

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  1. Introduction to Chemistryfor Allied Health SciencesThe Nucleus & Radioactivity Kirk HunterChemical Technology DepartmentTexas State Technical College Waco

  2. Nuclear Radiation

  3. Nuclear Radiaition • Originates at the nuclei of atoms • Some nuclei are unstable. • Radioactive nuclides • Parent nuclide changes with time into an atom with a different nucleus, called the daughter nuclide. • Radioactive decay

  4. Radioactive Decay • Unstable nuclei decay by emitting a particle. • Alpha • Beta • Gamma • The nucleus changes to a more stable one through one or more decays.

  5. Half-Life • Time required for one half of a sample of the nuclide to decay. Phosphorus-32 P-32  P-32  P-32  P-32 14 days  14 days  14 days  14 days 64 µg 32 µg  18 µg  8 µg

  6. Radioactive Half-life Half-life – the amount of time required for one-half of a sample of a nuclide to decay. 1 half-life 1 half-life P-32  P-32  P-32 14 days 14 days 64 g 32 g 16 g

  7. Radioactive Half-lives Isotope Half-life C-14 5730 years U-238 4.5*109 years Po-214 1*10-3 seconds N-13 10 minutes P-32 14 days I-131 8.0 days

  8. Types of Radiation • Alpha Particle (α) • Helium nucleus 42He • Beta Particle (β) • Electron 0-1e • Gamma ray (γ) • No measurable mass • Similar to x-rays

  9. Types of Radiation Radiation Symbol Relative Type Mass Alpha Particle (α) 42He Heavy Beta Particle (β) 0-1e Light Gamma ray (γ) 00γ None

  10. Fission Chain Reactions • One neutron from each fission event produces another fission event. • Chain reaction • Process is critical. • Subcritical – not enough neutrons produced to sustain a chain reaction • Supercritical – more neutrons than necessary are produced leading to an uncontrolled chain reaction

  11. Fisson Splitting large nuclei into smaller nuclei with the release of energy.

  12. Nuclear Power Reactor

  13. Nuclear Equations Alpha Decay 21084Po  20682Pb + 42He Beta Decay 146C  0-1e + 147N Gamma Decay 99m43Tc  9943Tc + 00γ

  14. Fusion Combines smaller nuclei into larger ones releasing energy. 21H + 21H  42He + energy http://www.jet.efda.org/pages/content/fusion1.html

  15. Detecting Radiation • Ionizing radiation • Electron is knocked from the atom • Detection • Film (x-ray film) • Geiger-Muller tube / Geiger counter • Scintillation detector • Measure light produced when struck by radiation

  16. Units of Radiation • Curie (Ci) – disintegrations per second (dps) • 1 Ci = 3.7 * 1010 dps • Radiation Absorbed Dose (rad) • Amount of energy • 1 rad = 0.01 J / kg of tissue • Radiation Equivalent Man (rem) • 1 rem = 1 rad * RBE • RBE = relative biological effectiveness

  17. Protection • Shielding • Alpha – low energy, slow • paper • Beta – medium energy, intermediate • lead • Gamma – high energy, very fast • lead

  18. Nuclear Transformations • Conversion of one nucleus into another by bombardment with another. 10n + 23892U  23992U  23993Np + 0-1e 23993Np  23994Pu + 0-1e • Cancer treatment (Co-60) 5927Co + 10n  6027Co + 00γ

  19. Uses of Radionuclides • Food Processing • Improves shelf-life • Kills bacteria and other microorganisms • Reduce insect damage • Retard sprouting in root crops • Poor public perception and acceptance • Nuclear medicine • Xrays • Tracers – blood flow, tumor/cancer detection • I-123, Na-24, Tc-99m, F-18 • Cancer Treatment • Co-60 , I-131

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