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Basic radiation 061706

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Basic radiation 061706

  1. 1. Basic RadiationAnimations in this training work best in Windows XP May 2006
  2. 2. Topics• Introduction to Radiation• Types of Radiation• How Radiation Interacts with the Environment• Radiation Safety• Why We Need to Measure Radiation Today
  3. 3. Introduction to Radiation• Radiation can be non-ionizing or ionizing• Non-ionizing radiation is generally a low energy electromagnetic wave – Sunlight – Radio waves – Microwaves – Infrared waves• Mostly harmless
  4. 4. Ionizing Radiation• Ionizing (nuclear) radiation has enough energy to ionize the atoms and molecules it interacts with – Particles: alpha, beta, neutron – Waves: gamma• Because it can ionize, it can cause biological damage
  5. 5. Introduction to Radiation• Ionizing Radiation is all around us – We are constantly exposed to low levels of radiation from outer space, the earth, and medical treatments – Low levels of naturally occurring radioactive material are in our environment, the food we eat, and in many consumer products – Some consumer products also contain small amounts of man-made radioactive material – However, exposure to large doses of radiation is definitely not desirable – Most of your annual dose of radiation comes from Radon gas in your house!
  6. 6. Topics• Introduction to Radiation• Types of Radiation• How Radiation Interacts with the Environment• Radiation Safety• Why We Need to Measure Radiation Today
  7. 7. Types of Radiation
  8. 8. The AtomCarbon-12: • 6 Protons • 6 Neutrons • 6 Electrons Particle Location Charge Relative Mass Proton Nucleus +1 1 Neutron Nucleus neutral 1 Electron Orbit -1 1/1837
  9. 9. The AtomCarbon-12: • 6 Protons • 6 Neutrons • 6 Electrons Particle Determines… Proton Element Chemical & physical properties Neutron Isotope Radioactivity Electron Ion Some bonding & interaction
  10. 10. Unstable Atoms Decay• Certain atoms are radioactive because their nuclei are unstable – They have too few or too many neutrons, which creates an imbalance• To get stable, the atom “decays” and transforms into a new atom by emitting radiation in 4 forms: – Alpha particle (α) – Beta particle (β) – Gamma wave (γ) – Neutron particle (n)• Sometimes the new atom is also unstable, and it decays too, creating a “decay chain”UCRL-PRES-149818. Understanding Radiation and it’s Effects.
  11. 11. Source Activity• The number of decays per unit time tell us how radioactive a source is. This is called activity.• Measured in Curies (Ci) or Becquerels (Bq) – 1 Becquerel = 1 Bq = 1 decay per second – 1 Curie = 1 Ci = 3.7 x 1010 Bq – 1 Ci = the activity of 1 gram of Radium-226
  12. 12. Half Life• The half life of a radioactive material tells us how quickly it decays away• Half life = how long it takes for ½ of the radioactive atoms in a sample to decay away• Measured in units of time• Some examples: – Some natural isotopes (like Uranium and Thorium) have half lives that are billions of years – Most medical isotopes (like Technicium-99m) last only a few daysUCRL-PRES-149818. Understanding Radiation and it’s Effects.
  13. 13. Alpha Decay• A +2 charged helium nucleus with 2 protons and 2 neutrons• Relatively heavy particle with a big charge• Travels 2-5 cm in air• Stopped by a piece of paper, or the top layer of your skin• Difficult to detect• Dangerous if inhaled– will cause localized severe damage to a thin layer of tissue in the lungs and respiratory tract- possible precursor to lung cancer• Radioactive “beach ball”
  14. 14. Beta Decay• Negatively (or positively) charged electron• Relatively light particle, but still charged• Travels ~10 meters in air• Stopped by aluminum foil, glass plate or 2.5 cm of virtually anything• Difficult to detect• Dangerous if inhaled– will cause localized severe damage to a thin layer of tissue in the lungs and respiratory tract- possible precursor to lung cancer• Radioactive “golf ball”
  15. 15. Gamma Decay• Energetic electromagnetic wave (photon) with no charge• Travels many kilometers/miles in air• Stopped by lead or concrete 10+ cm thick• Relatively easy to detect and direct exposure is likely• Normal to be exposed to small amounts everyday from ground radiation and cosmic rays• γ rays vs. x-rays – γ rays are emitted from the nucleus of an atom – X-rays are emitted from the orbital electrons of an atom• Radioactive “9mm bullet”
  16. 16. Neutron “Decay”Small, neutral particles (same size as a proton)• Travels many kilometers in air• Stopped by 30+ cm of water, polyethylene or paraffin – Spent fuel rods are stored in water• Self-fissioning radioactive materials (Plutonium, Californium) give off neutrons• Large doses can do significant damage to people
  17. 17. Types of Radiation Type of Travel Distance in Air & Means Physical Structure Radiation of Attenuation Positively charged ~1-2 inches Alpha Helium nucleus (2 Stopped by a single sheet of Particles protons & 2 neutrons) paper ~30 feet Positively or negativelyBeta Particles Stopped by aluminum foil, glass charged electrons plate, ~1 inch of anything Many milesGamma Rays Neutral, energetic (Photons) electromagnetic wave Stopped by thick lead (4 inches) or very thick concrete Small, neutral particles Many miles Neutrons with mass very near a Stopped by 12 inches of water, proton polyethylene, paraffin
  18. 18. Topics• Introduction to Radiation• Types of Radiation• How Radiation Interacts with the Environment• Radiation Safety• Why We Need to Measure Radiation Today
  19. 19. What is a “Dose” of Radiation?• When radiation hits your body, and it’s energy is transferred to your tissue, you have received a dose of radiation.• The more energy deposited, the higher your dose.• Measured in Roentgen Equivalent Man (rem) or sieverts (Sv – SI unit)• Rads and Roentgens (R) are similar units that are often equated to the rem.
  20. 20. Topics• Introduction to Radiation• Types of Radiation• How Radiation Interacts with the Environment• Radiation Safety• Why We Need to Measure Radiation Today
  21. 21. Radiation Safety• The fundamental principle of radiation safety is that radiation exposures should be maintained As Low As Reasonably Achievable (ALARA).• The three factors influencing radiation dose are: – Time – Distance – Shielding
  22. 22. ALARA - Time• The less time you’re exposed, the less exposure you get• Dose = Dose Rate x Time• If you want to limit your exposure to 100 µRem and the source is 200 µRem/hr then only stay near the source for 30 minutes: 200 µRem/hr x 0.5 hr = 100 µRem• Limit your time near the radiation source!
  23. 23. ALARA - Distance• The farther away from the source you are, the weaker the source is to you• Exposure levels are based upon the inverse square law• Increase the distance between you and the source!
  24. 24. ALARA - Shielding• Shielding can stop the radiation from hitting you• Exposure levels can be reduced greatly by putting shielding between yourself and the radiation source – α can be absorbed by a piece of paper – β can be absorbed by 1” of aluminum or glass – γ can be absorbed by thick lead shields – n can be absorbed by paraffin, water, polyethylene• Increase the amount of shielding material between you and the source!
  25. 25. Shielding/Attenuating Radiationn γ β Glass, thin metaln γ α βn γ α Polyethylene Paper Concrete β Lead,n γ α Water, β α
  26. 26. Water,Shielding/Attenuating Radiation Polyethylene Lead, Concrete Glass, thin metal Paper α β γ η
  27. 27. Radiation Safety• Another danger to the body is through the entry of radioactive substances into the body rather than a short external exposure to radiation.• Routes of entry to the body: s Air  Lungs , e.g. Radon Gas s Food, drinking water  Mouth  Bloodstream, GI tract s Body Cuts  Bloodstream• Once in the body, the radioactive substance is the “gift that keeps on giving”• However, the human body is very resilient, and has very efficient repair mechanisms to deal with small, normal amounts of radiation damage
  28. 28. Irradiated or Contaminated?• Irradiated – You are “irradiated” when radiation hits you – You do NOT become radioactive when you are irradiated – Some forms of radiation CAN penetrate personal protective clothing
  29. 29. Irradiated or Contaminated?• Contaminated – Contamination is radioactive dirt – You can become contaminated by touching radioactive dirt – Contamination can be washed off like any dirt – Personal protective equipment can protect people from contamination
  30. 30. Typical Yearly Radiation Dosage Average Annual Radiation Dosage* Radon in homes (~240 mRem) Medicine (70 mRem) Natural radiation from ground (50 mRem) Natural activity in body (40 mRem) Cosmic radiation (30 mRem) Others (10 mRem)• Total average annual dosage: 440 mRem• Annual dosage can be increased by smoking, living at higher elevations, living in a brick, stone or concrete house, flying, plutonium-powered pacemakers, watching TV, medical x-rays.• Calculate your own exposure at: http:// www.epa.gov/radiation/students/calculate.html * Understanding Radiation: Bjorn Wahlstrom
  31. 31. Common Doses in Everyday Life** Dosage Cause of Dose µSv µrem 100 10,000 Average annual chest x-ray exposure2000 200,000 Annual exposure from radon gas in homes 810 81,000 Annual background radiation exposure at high elevation (Denver)14,000 1,400,000 Gastro-intestinal Barium x-ray (GI series) ** Hazardous Materials Air Monitoring and Detection Devices: Chris Hawley
  32. 32. Important Dose Limits** Dose Rate Limit Description of Limit µSv µrem 10 1,000 Limit for normal public activities50,000 5,000,000 Limit for all activities100,000 10,000,000 Limit for protecting valuable property (10 rem)250,000 25,000,000 Limit for lifesaving or protection of (25 rem) large populations>250K >25,000,000 Limit for lifesaving or protection of (>25 rem) large populations only on a voluntary basis for persons aware of the risks ** Hazardous Materials Air Monitoring and Detection Devices: Chris Hawley
  33. 33. Acute Radiation Doses Dose (Rads*) Effects 25 – 50 First sign of physical effects – (~25,000,000 – 50,000,000 µrem) drop in white blood cell count 100 Vomiting within several hours (~100,000,000 µrem) of exposure 320 – 360 ~50% die within 60 days with(~ 320,000,000 – 360,000,000 µrem) minimal supportive care 480 – 540 ~50% die within 60 day with(~480,000,000 – 540,000,000 µrem) supportive care 1,000 ~100% die within 30 days (~ 1,000,000,000 µrem)*1 Rad can be approximated to 1 rem = 1,000,000 µrem = for common external exposures
  34. 34. Topics• Introduction to Radiation• Types of Radiation• How Radiation Interacts with the Environment• Radiation Safety• Why We Need to Measure Radiation Today
  35. 35. Why Detect Radiation Today?• Medicine – Imaging – Cancer treatment and therapy• Industrial – Imaging – Gauges• Power• Agriculture• Radiological terrorism
  36. 36. Radiological Terrorism• Radiological Terrorism is a real and possible threat – High psychological/emotional impact – High economic impact – Many devices are easy to build – Al Qaeda has threatened radiological terrorism – It’s already being done• Improvised Nuclear Device• Radiological Dispersion Devices (RDDs)• Radiation detection covers two letters of CBRNE preparedness: Radiological and Nuclear
  37. 37. Radiological Terrorism• Nuclear warheads use special nuclear materials and fission or fusion to create a nuclear payload• Plutonium 239 and Uranium 235 are the special nuclear materials used in weaponry• Medical and industrial radioactive materials CANNOT produce a nuclear warhead– they can only be used to contaminate!!!
  38. 38. Threat Comparison Stolen nuclear weapon ImprovisedSeverity of incident nuclear device RDD Probability of incident
  39. 39. Radiological Dispersion Devices• Radiological dispersion devices (RDDs) can take two main forms: – A dirty bomb- a core of radiological material wrapped in conventional explosives – A simple radioactive source left discretely in a public place• The key to these devices is NOT destruction- it’s fear and contamination. It is a psychological and “denial of service” attack on the economy.
  40. 40. Making an RDD• All you need is radiological material• Optional: Explosives• Orphan sources – Radiological materials are used everyday in a variety of applications – Some sources are lost, forgotten, or disposed of improperly – Orphan sources – Over 200,000 available today
  41. 41. Example of an RDD• 1 pound of HE, two patient doses of liquid Technetium-99m (Tc-99m) near the HE• Weather: 30 degrees F, sunny, light winds with gusts of 20 mph• Tc-99m chosen due to level of radioactivity (high), short half-life, environmentally safe daughters, and availability
  42. 42. Example of an RDD• Contamination measured at 4 times background• Due to short half-life, Tc-99m decayed to non- hazardous daughters within 60 hours
  43. 43. Threats
  44. 44. Commonly Orphaned Isotopes Commonly Available Isotopes That Are Suitable For RDDs Radioisotope Half-Life Alpha Beta Emission Gamma Neutron Detect with Emission Emission Emission GammaRAE II? Cobalt-60 5.3 yrs No Low Energy High Energy No Yes Cesium-137 30 yrs No Low Energy Delayed No Yes High Energy Iridium-192 74 days No High Energy High Energy No Yes Stronium-90 29 yrs No High Energy No No Yes Americium-241 433 years High No Low Energy No Yes Energy Californium-252 2.6 years High No Low Energy Yes Yes Energy (Spont. Fission) Plutonium-238 88 yrs High No Low Energy Yes Yes Energy (Spont. Fission)Source: “Commercial Radioactive Sources: Surveying the Security Risks," Monterey Institute of International Studies, 1/2003
  45. 45. “Innocent” Sources• Innocent Source: a radioactive source seen in typical day to day operations – May be the source of “false” alarms – Could be used to shield/disguise a real source• Ship/truckloads of tile, bricks• Containers of bananas, fertilizer containing potassium• Patients who have received radioactive iodine, barium or other nuclear medicine treatments
  46. 46. Summary• Radioactivity is all around us – There are 4 types of radiation: alpha, beta, gamma, and neutron• Radiation is used in many applications in everyday life• Radiation can also be used for malicious/terrorist acts• Knowing more about radiation can help to better understand the threat, and reduce the chances of an occurrence
  47. 47. Questions?www.raesystems.comelang@raesystems.com
  48. 48. Additional Slides• Additional Slides
  49. 49. Mishaps
  50. 50. Mishaps
  51. 51. Terrorist Attacks
  52. 52. RDDs
  53. 53. RDDs
  54. 54. RDDs
  55. 55. Material Attacks
  56. 56. Material Theft
  57. 57. Specific Activity• Specific Activity refers to the activity of 1 gram of a radioactive material• Different isotopes have different specific activities.• The longer the half-life of the isotope, the lower the specific activity of the isotope. – 1 gram of cobalt-60 has the same activity as 3300 metric tons of uranium-238
  58. 58. Some Isotopes & Their Half-Lives Isotope Half-Life ApplicationsUranium billions of Natural uranium is comprised of several different years isotopes. When enriched in the isotope of U-235, it’s used to power nuclear reactor or nuclear weapons.Carbon-14 5730 y Found in nature from cosmic interactions, used to “carbon date” artifacts and as radiolabel for detection of tumors.Cesium-137 30.2 y Blood irradiator, tumor treatment through external exposure. Also used for industrial radiography.Hydrogen-3 12.3 y Labeling biological tracers.Iridium-192 74 d Implants or "seeds" for treatment of cancer. Also used for industrial radiography.Technicium-9 6h Brain, heart, liver, lungs, bones, 9m thyroid, and kidney, regional cerebral blood flow imaging. UCRL-PRES-149818. Understanding Radiation and it’s Effects.
  59. 59. Exposure• Exposure: how much radiation “hits” an object (or person)• Measured in Roentgens (R)• Visualize the amount of light emitted by the sun that hits you while sitting on the beach
  60. 60. Absorbed Dose• Absorbed dose: how much energy is imparted on/transferred to the object by the radiation• Measured in Rads (Radiation Absorbed Dose) or Grays (Gy) – Units of energy/mass – 1 Gy = 100 rad• Imagine how much your skin heats up from the sunlight hitting it
  61. 61. Biologically Equivalent Dose• Biologically equivalent dose: Radiation-weighted dose to quantify the effects of radiation on biological tissue• Measured in Roentgen Equivalent Man (rem) or Sieverts (Sv) – 1 Sv = 100 rem• Imagine how sunburnt you get from sitting out in the sun
  62. 62. How Radiation Interacts• Imagine you’re relaxing on the beach on a sunny day: – The amount of light the sun emits is the “activity” of the sun – The amount of light that hits your skin is your exposure – The amount your skin heats up is your “absorbed dose” – The amount of sunburn you get is your “biologically equivalent dose”
  63. 63. Radiation UnitsType Unit DefinitionSource activity Curie (Ci) 3.7 x 1010 disintegrations/second Becquerel (Bq) 1 disintegration per secondExposure (X & 2.58 x 10-4 Coulombs/Kg in dry air atgamma rays) Roentgen (R) STP 1 Coulomb per 1cc dry air at STP 0.01 J /KgAbsorbed dose rad 1 J /Kg Gray (Gy) 1Gy = 100 Rad Biologically Rem QFR x (dose in rad)equivalent dose Sievert (Sv) QFG x (dose in Gray)
  64. 64. Radiation Equivalents Millirem Microrem Rem (mrem) (µrem) 1 1,000 1,000,000 0.1 100 100,000 0.01 10 10,000 0.001 1 1,000 0.0001 0.1 1000.00001 0.01 100.000001 0.001 1
  65. 65. Radiation Equivalents Unit Measured QuantityRad, Grey (Gy) Absorbed DoseRem, Sievert (Sv) Biologically Equivalent Dose Unit Equivalents100 Rem 1 Sv1 Rem 10 mSv (millisievert)1 mrem (millirem) 10 µSv (microsievert)1 µrem (microrem) 0.01 µSv
  66. 66. Radioactive Contamination• Radiation cannot make you radioactive* * Understanding Radiation: Bjorn Wahlstrom
  67. 67. Radioactive Contamination• Radioactive contamination can stick to clothes & skin. It can be washed away like any dirt*. * Understanding Radiation: Bjorn Wahlstrom
  68. 68. • When most people think of radiation, they think of the mushroom cloud from the atomic bomb tests in the 1940’s & 50’s.• If people thought the same way about electricity, their first image would be of the electric chair instead of the light bulb!• The goal of this presentation is to demystify radiation 1952, Operation Ivy, “Mike” H-Bomb

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