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Nuclear Science Merit Badge

Nuclear Science Merit Badge

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Nuclear Science Merit Badge

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  1. Nuclear Science Merit Badge Howard Matis Lawrence Berkeley National Laboratory Howard Matis - hsmatis@lbl.gov

  2. Radiation gives Superhuman Powers to Spiderman Howard Matis - hsmatis@lbl.gov

  3. Radiation gives Superhuman Powers to The Hulk Howard Matis - hsmatis@lbl.gov

  4. Chernobyl Howard Matis - hsmatis@lbl.gov

  5. Radiation is • Plot device for fiction • Scary • Deadly • Life saving • Misunderstood • Useful Howard Matis - hsmatis@lbl.gov

  6. 60° 60° R 1.5R 5R Radiation Hazard Symbol • The symbol is placed on a placard with the word CAUTION or DANGER or GRAVE DANGER centered about it. Under the symbol is the information addressing the types of hazards. • Examples are: • Radiation Area High Radiation Area Airborne Radioactivity Area Contaminated Area Radioactive Materials Area Howard Matis - hsmatis@lbl.gov

  7. Radiation is Energy • The energy is given off by unstable (radioactive) atoms and some machines. We will be focusing on ionizing radiation and its health effects. Howard Matis - hsmatis@lbl.gov

  8. Atoms Building Blocks of Matter • All matter is made up of atoms • The nucleus is in center • almost all of the mass • Electrons go around • At this scale, electrons are at the edge of town Howard Matis - hsmatis@lbl.gov

  9. What is a Nucleus? • Quarks determine if proton or neutron • Neutrons • Protons • Protons determine chemical properties • Ratio of neutrons to protons make a nucleus stable or unstable Howard Matis - hsmatis@lbl.gov

  10. Isotopes • Many elements have nuclei with the same number of protons • same name • same chemistry • but different numbers of neutrons • different masses Howard Matis - hsmatis@lbl.gov

  11. Examples - Isotopes • Hydrogen (1H) • 1 proton, 0 neutrons, mass 1 • Deuterium (2D) • 1 proton, 1 neutron, mass 2 • Tritium (31T) • 1 proton, 2 neutrons, mass 3 • Helium (4He) (a-particle) • 2 protons, 2 neutrons, mass 4 • Helium-3 (3He) • 2 protons, 1 neutron, mass 3 • Uranium-238 (238U) • 92 protons, 146 neutrons, mass 238 • Uranium-235 (235U) • 92 protons, 143 neutrons, mass 235 Howard Matis - hsmatis@lbl.gov

  12. Types of Radioactivity Six Common Types Alpha Decay Beta Decay Gamma Decay Fission Fusion Cosmic Rays • Each type of radiation is ionizing • But different properties • affect the hazards they pose • the detection mechanism • shielding Howard Matis - hsmatis@lbl.gov

  13. How Does it Decay? • Alpha - lose an alpha particle ( - helium nucleus) • Beta - emit a beta particle ( - electron or anti-electron) • Gamma - emit a gamma ( or photon or light particle) Howard Matis - hsmatis@lbl.gov

  14. Alpha Decay • Alpha particle or helium nucleus emitted • Nucleus changes mass by four units and charge by two units • Common for heavy elements • Changes chemical properties • Alpha particle easily stopped • 4 x nucleon mass • +2 Charge • Big Howard Matis - hsmatis@lbl.gov

  15. Beta Decay • Beta minus - neutron converts to electron and anti-neutrino • Beta plus - proton converts to a anti-electron and neutrino • Nucleus changes charge but not mass number • Changes chemical properties • Radiation moderately penetrating • +1 charge • Small electron Howard Matis - hsmatis@lbl.gov

  16. Gamma Decay • Nucleus changes energy level • Emits gamma ray or photon • Nucleus stays the same • No change in chemical properties • Very penetrating • Almost no size • Neutral Howard Matis - hsmatis@lbl.gov

  17. Paper Plastic Lead Concrete a++ Alpha 0b- Beta 0g Gamma and X-rays 1n Neutron Absorption of Radiation Howard Matis - hsmatis@lbl.gov

  18. Fission Sometimes a very heavy nucleus will fall apart before it can emit an alpha particle. The heavy parent nucleus fissions … … into two lighter (radioactive) fission fragment nuclei plus some left over neutrons Fission can release an enormous amount of energy and is utilized in power plants and fission bombs (A-bomb). Howard Matis - hsmatis@lbl.gov

  19. Fusion • When two nuclei collide and stick together • Process that powers the sun and stars • All life arises from it • Not usually found in every day experience on Earth • Component of the H-bomb Howard Matis - hsmatis@lbl.gov

  20. How Unstable Is It? • The “Half-life” describes how quickly Radioactive Material decays away with time.It is the time required for half of the unstable atoms to decay. • Some Examples: • Some natural isotopes (like uranium and thorium) have half-lives that are billions of years • Since Earth is about 5 billion years old, short lived naturally produced isotopes gone • Most medical isotopes (like 99mTc) last only a few days Howard Matis - hsmatis@lbl.gov

  21. Half-Life Experiment Guess the number I am thinking from 1 to 4 Howard Matis - hsmatis@lbl.gov

  22. Some Isotopes & Their Half Lives Howard Matis - hsmatis@lbl.gov

  23. How do we Measure the Amount of Radiation? Howard Matis - hsmatis@lbl.gov

  24. Radiation Absorbed Dose Qty: Dose Unit: rad (Gray) 1 rad = 1000 mrad 1 rad = 100 erg/gram 1 Gy =100 rad Radioactivity Qty: Activity Unit: Curie (Bequerel) 1 Ci = 1000 mCi 1 Bq = 1 disintegration/sec 1 Ci = 3.7  1010 Bq Roentgen equivalent man Radiation Risk Qty: Dose Equivalent Unit: rem (Sievert) 1 rem = 1000 mrem 1 Sv=100 rem Radiation Quantities and Units Howard Matis - hsmatis@lbl.gov

  25. Convert from Curies to Rad • Curie is the number of decays/s • 1 Curie = 3.7  1010 decays/s (exactly) • Rad is the absorbed dose or physical dose • Amount of energy deposited in unit mass • human tissue or other media • 1 Rad = 100 erg/g • Often use gray • 1 J/kg • 1 gray = 100 rad Howard Matis - hsmatis@lbl.gov

  26. Need Biological Dose – REM • To convert from rad to rem multiply by appropriate value of Q • Q is the Quality Factor • Q reflects the damage rad  Q = rem Howard Matis - hsmatis@lbl.gov

  27. Radiation and Health Does radiation affect you? Howard Matis - hsmatis@lbl.gov

  28. Ionizing Radiation can Damage DNA Ionizing radiation has the ability to ionize* atoms and molecules, possibly altering structure and function. * ionize = produce positive and negative electrical charge Howard Matis - hsmatis@lbl.gov

  29. Alpha Radiation Is Only a Hazard When Inside Your Body (Internal Hazard) Your skin will stop it can’t penetrate skin internal hazard stopped by paper found in soil, radon and other radioactive materials Howard Matis - hsmatis@lbl.gov

  30. Beta Radiation Is a Skin, Eye and Internal Hazard skin, eye and internal hazard stopped by plastic found in natural food, air and water Howard Matis - hsmatis@lbl.gov

  31. found in medical uses stopped by lead naturally present in soil and cosmic radiation X-ray and Gamma Radiation Are Penetrating Radiation and an External Hazard Howard Matis - hsmatis@lbl.gov

  32. - + How does Radiation Injure Cells? • High energy radiation breaks chemical bonds. • This creates free radicals, like those produced by other insults as well as by normal cellular processes in the body. • The free radicals can change chemicals in the body. • These changes can disrupt cell function and may killcells. Howard Matis - hsmatis@lbl.gov

  33. Types of Exposure & Health Effects • Acute Dose - Deterministic • Large radiation dose in a short period of time • Large doses may result in observable health effects • Early: Nausea & vomiting • Hair loss, fatigue, & medical complications • Burns and wounds heal slowly • Examples: medical exposures andaccidental exposure to sealed sources • Chronic Dose - Stochastic • Radiation dose received over a long period of time • Body more easily repairs damage from chronic doses • Does not usually result in observable effects • Examples: Background Radiation andInternal Deposition Inhalation Howard Matis - hsmatis@lbl.gov

  34. At HIGH Doses, We KNOW Radiation Causes Harm • High Dose effects seen in • Radium dial painters • Early radiologists • Atomic bomb survivors • Populations near Chernobyl • Medical treatments • Criticality Accidents • Cancer • Leukemia (A-bomb data) • Thyroid (Chernobyl data) • Bone and other solid cancers (A-bomb data) • Birth defects (A-bomb data) • Genetic effects (only animal data) . Howard Matis - hsmatis@lbl.gov

  35. Effects of ACUTE (Deterministic) Exposures * For common external exposures 1 rad ~ 1 rem = 1,000 mrem Howard Matis - hsmatis@lbl.gov

  36. At LOW Doses, We PRESUME Radiation Causes Harm • No physical effects have been observed The Bad News: Radiation is a carcinogen and a mutagen The Good News: Radiation is a very weak carcinogen and mutagen! Very Small DOSE = Very Small RISK Howard Matis - hsmatis@lbl.gov

  37. Sources of Radiation • Average radiation exposure in the United States • 360 mrem or • 0.360 rem • Very location dependent Howard Matis - hsmatis@lbl.gov

  38. Manufactured Sources of Radiation Contribute an Average of 60 mrem/year cigarette smoking - 1300 mrem lung dose medical - 53 mrem building materials - 3.6 mrem smoke detectors - 0.0001 mrem Howard Matis - hsmatis@lbl.gov

  39. Risks in Perspective 1 in 1 million chance of fatality • 40 tablespoon peanut butter (aflotoxin) • 2 days in New York City (air quality) • 3 mrem radiation (cancer) • 1 mile on motorcycle (collision) • 300 miles in car (collision) • 10 charbroiled steaks • Smoking 1 cigarette Howard Matis - hsmatis@lbl.gov

  40. ALARA ALARA stands for As Low As Reasonably Achievable Reduce radiation dose by using: • Time • Distance • Shielding Howard Matis - hsmatis@lbl.gov

  41. Reduce Time Spend as short as time as necessary to complete the task Howard Matis - hsmatis@lbl.gov

  42. Activity Demonstrate Time – (t) Howard Matis - hsmatis@lbl.gov

  43. Increase Distance Twice the distance = ¼ of the dose Howard Matis - hsmatis@lbl.gov

  44. Activity Demonstrate Distance – (d) Howard Matis - hsmatis@lbl.gov

  45. Use Shielding Howard Matis - hsmatis@lbl.gov

  46. Activity Demonstrate Shielding – (s) Howard Matis - hsmatis@lbl.gov

  47. Reactors Glow in the Dark • Reactor core emits electrons • Electrons move faster than the speed of light in water • At that speed they emit blue light • Cherenkov Radiation • Similar to sonic boom or wake of a boat Howard Matis - hsmatis@lbl.gov

  48. Can You Glow in the Dark? • Ingest a very hot radiation source • Beta needed • Short half life • Do not swallow • Unless your midriff is exposed • Or inject source into your blood • Don’t be in direct light • Usually too faint for sunlight • Try it for Halloween? Howard Matis - hsmatis@lbl.gov

  49. Summary • Radiation is part • Our natural environment • Technology • Health effects • Known for high doses • Unknown for low • You deal with it regularly Howard Matis - hsmatis@lbl.gov

  50. The End Howard Matis - hsmatis@lbl.gov