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Basic radiation 061706

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  • When an atom is ionized, electrons are added or removed from it, giving it a negative or positive charge. More on this later.
  • Protons and neutrons are located in the nucleus in the center of the atom, and are therefore called “nucleons.” The number of protons in the nucleus of an atom tells you what element it is and what chemical and physical properties it has. For example, Hydrogen has 1 proton, Helium has 2 protons, Carbon has 6, Oxygen has 8, Lead has 82, Uranium has 92, and Plutonium has 94. The number of neutrons in the nucleus determines what isotope of the element you have. The isotope is named by the number of nucleons (protons and neutrons), which is also called the mass number . In this example, the Carbon atom had 6 protons and 6 neutrons, or 12 nucleons, and is called Carbon-12. Electrons orbit around the nucleus. When an atom is ionized, extra electrons are added or some of the atom’s electrons are removed. This gives the atom a negative or positive charge, and it is then called an ion . Ionizing radiation can create ions.
  • Protons and neutrons are located in the nucleus in the center of the atom, and are therefore called “nucleons.” The number of protons in the nucleus of an atom tells you what element it is and what chemical and physical properties it has. For example, Hydrogen has 1 proton, Helium has 2 protons, Carbon has 6, Oxygen has 8, Lead has 82, Uranium has 92, and Plutonium has 94. The number of neutrons in the nucleus determines what isotope of the element you have. The isotope is named by the number of nucleons (protons and neutrons), which is also called the mass number . In this example, the Carbon atom had 6 protons and 6 neutrons, or 12 nucleons, and is called Carbon-12. Electrons orbit around the nucleus. When an atom is ionized, extra electrons are added or some of the atom’s electrons are removed. This gives the atom a negative or positive charge, and it is then called an ion . Ionizing radiation can create ions.
  • Narrative “ Atoms are the building blocks of our world, we are made from atoms, as is the air we breath and the world we live in. If you recall your high school “Table of Elements,” there are a little over 100 different elements, or “flavors” of atoms. Everything above Element number 89 (Bismuth) is unstable. This includes the uranium and thorium we dig out of the ground as well as man-made elements such as plutonium and Americium . Even the “stable” elements have unstable “brothers and sisters” that chemically behave identically to their stable sibling, but are radioactive. Again, these unstable brethren, or isotopes, include naturally occurring isotopes like Carbon-14 and Tritium (a radioactive form of Hydrogen) and man-made isotopes like Cesium-137 and Iodine-131. UNSTABLE ATOMS DECAY I often relate this to the hyperactive brother, who just has too much energy. The unstable atoms eventually get rid of this energy by “ Decaying, ” or more accurately “ Transforming, ” to different element. During this process, they get rid of excess energy by giving off radiation. We define how radioactive something is by how many decays occur in a given amount of material over a given time. In fact, one of our oldest units was defined by Madam Curie as the number of decays in 1 gram of radium . This unit, named after her as “The curie” turned out to be 37 billion decays per second. Which, explains why Marie died of Leukemia and had lesions on her hip from carrying her precious Radium in her lab coat pocket. When atoms decay, they release much of their excess energy in the form of radiation. There are two main types of radiation; Gamma rays are electromagnetic radiation, like light and radio-waves… except that these photons have enough energy to strip off the outer electron, or “ionize,” any atoms that they hit. During the Decay Process, particles are also ejected from the nucleus. The most common of these, alpha, beta, and Neutron particles , are ejected with enough energy to also ionize other atom that they hit. Often, unstable atoms transform into another unstable atom! This can lead to a series of transformations, or “decay chain.” As you can see by the graphic, the most common Uranuim isotope actually goes through 14 different decays before reaching a stable lead isotope.
  • Activity was discovered by Madame Curie. She discovered it using Radium-226, and therefore named the unit of activity the Curie, and defined it as the activity of one gram of Radium-226. Becquerel came along later. We need to know Curies based on what will set off a radiation detector.
  • Technicium-99m (m means metastable) is used for medical imaging. It is formed by *** Narrative How Unstable an atom is will drive the speed at which it decays. Some unstable atoms last for billions of years and are older than the Earth itself, others have a hard time staying around a microsecond after it was created. Since this is a random process, we don’t know exactly when any specific unstable atom will decay…. But, on average, we know how long it takes for half of a group of unstable atoms to decay . This measurement of time is called the half-Life. After each “half-life,” half of the remaining unstable atoms would transform. The Picture can help visualize this. Each dot represents an unstable atom. The first picture is almost black because of them. After one half life, half are gone. After another half-life, half of the remaining atoms are gone. Statistically, even after 10 half lifes, there could still be a few unstable atoms hanging around… but their number will be one thousandth of the starting number of atoms. =============================== Additional Info ============== For non technical Overview, Change SLIDE to The number of “decays” that occur per unit time in the radioactive material tell us how radioactive it is. Radioactive Material “decays away” with time, though different isotopes decay away at different rates. For Example: Some natural isotopes (like uranium and thorium) have half-lives that are billions of years. Most medical isotopes (like I-131) last only a few weeks.
  • The animation shows the nucleus of an atom undergoing alpha decay. An alpha particle is ejected from the nucleus in order to stabilize the nucleus.
  • The animation shows the nucleus of an atom undergoing beta minus decay. During beta decay, a neutron is transformed into a proton and an electron (beta particle), and the beta particle is ejected in order to stabilize the nucleus. This is not the same as positron emission, in which a beta plus, or positron is emitted. During positron emission, a proton is transformed into a neutron and a positron, and the positron is emitted. Neutrinos are emitted with both decays, but are not important in this training.
  • This animation shows a nucleus undergoing gamma decay. Excess energy is released from the nucleus by gamma emission.
  • This animation shows a nucleus undergoing neutron emission. A neutron is emitted in order to released excess energy in the nucleus.
  • Summary table.
  • Dose = Dose Rate x Time, just like Distance Traveled = Speed x Time.
  • Another reason the source will be weaker at a distance is due to attenuation of the radiation, especially in the case of alpha and beta particles, which can only travel a given distance in air (5 cm for alpha, 10 meters for beta). If a source has a level of 20000  Rem/hr at r feet, then doubling the distance to 2r feet provides an exposure of 5000  Rem/hr (1/4 of 20000) Tripling the distance to 3r feet results in an exposure of 2222.2  Rem/hr (1/9 of 20000) This is because the same amount of radiation that hits area A at r feet away is spread out over 4A at 2r feet away. So, less radiation will hit each area A at 2r feet away than at r feet away.
  • Radioactive Cookie Example: You have 4 radioactive cookies (alpha, beta, gamma, neutron). You can eat one, hold one in your hand, put one in your pocket, and throw one away. What do you do with each cookie? Alpha: Hold in your hand. The top layer of dead skin will stop the alpha particles. Beta: Put in your pocket. The material in your clothing will stop the beta particles. Gamma: Eat it. The majority of the gammas will exit your body without depositing much energy into your cells. Neutron: Throw it far far away. Neutrons do not play nice with people.
  • Once in your body, many radioactive substances that either resemble, or are radioactive isotope of an element the body normally utilizes, stay in your body indefinitely. This means that they continue to irradiate you well after they’ve gotten into your system, resulting in a chronic radiation dose. Examples of materials that stick in your body are Pu-238 (bone marrow), Radon (often) sticks in your lungs.
  • It’s important to note that the 440 mRem received in this example IS NOT a big deal. It will not result in an increased risk of cancer or cause damage to the body. Radon in homes is a radioactive gas that comes from the ground, and usually enters through the basement.
  • An Improvised Nuclear Device is a nuclear warhead. This is the ultimate terrorist weapon, but is unlikely.
  • A dirty bomb is NOT an atom bomb or nuclear warhead.
  • Orphan sources can be anything from hospital imaging and cancer treatment equipment and sources, to industrial gauges. They can be medical sources such as Cobalt-60 or Cesium-137, or sources from radioisotope thermal generators (Uranium-238, Strontium-90). Radioisotope thermal generators use the heat given off when an atom decays to power a generator. They are used in the remote northern regions of Russia. Military sources: 20 nuclear suitcase bombs went missing from Russia
  • There are seven main isotopes that are considered viable, available and likely for an RDD.
  • RDDs can be “hidden” by an “innocent” source. For example, an RDD could be buried in a banana or fertilizer truck, and go unnoticed through a checkpoint. Innocent sources can also cause false alarms in radiation detection equipment. The key is knowing what to expect.
  • Orphan sources can be anything from hospital imaging and cancer treatment equipment and sources, to industrial gauges. They can be medical sources such as Cobalt-60 or Cesium-137, or sources from radioisotope thermal generators (Uranium-238, Strontium-90). Radioisotope thermal generators use the heat given off when an atom decays to power a generator. They are used in the remote northern regions of Russia. Military sources: 20 nuclear suitcase bombs went missing from Russia
  • Orphan sources can be anything from hospital imaging and cancer treatment equipment and sources, to industrial gauges. They can be medical sources such as Cobalt-60 or Cesium-137, or sources from radioisotope thermal generators (Uranium-238, Strontium-90). Radioisotope thermal generators use the heat given off when an atom decays to power a generator. They are used in the remote northern regions of Russia. Military sources: 20 nuclear suitcase bombs went missing from Russia
  • Orphan sources can be anything from hospital imaging and cancer treatment equipment and sources, to industrial gauges. They can be medical sources such as Cobalt-60 or Cesium-137, or sources from radioisotope thermal generators (Uranium-238, Strontium-90). Radioisotope thermal generators use the heat given off when an atom decays to power a generator. They are used in the remote northern regions of Russia. Military sources: 20 nuclear suitcase bombs went missing from Russia
  • Orphan sources can be anything from hospital imaging and cancer treatment equipment and sources, to industrial gauges. They can be medical sources such as Cobalt-60 or Cesium-137, or sources from radioisotope thermal generators (Uranium-238, Strontium-90). Radioisotope thermal generators use the heat given off when an atom decays to power a generator. They are used in the remote northern regions of Russia. Military sources: 20 nuclear suitcase bombs went missing from Russia
  • Orphan sources can be anything from hospital imaging and cancer treatment equipment and sources, to industrial gauges. They can be medical sources such as Cobalt-60 or Cesium-137, or sources from radioisotope thermal generators (Uranium-238, Strontium-90). Radioisotope thermal generators use the heat given off when an atom decays to power a generator. They are used in the remote northern regions of Russia. Military sources: 20 nuclear suitcase bombs went missing from Russia
  • Some substances aren’t as radioactive as others. The specific activity of Cobalt-60 is ?? The specific activity of natural U is ?? This is due to the differences in the half-lives of the isotopes. Cobalt-60 has a half-life of ?? Uranium-238 (most of natural Uranium is 238) has a half-life of ??
  • Is this really important? Narrative Here are some examples of radioactive isotopes commonly used in industry. {Read slide if time permits} ---------------------- note: this slide can be removed for an overview
  • This is here mainly for background. Units are not important, just the concept. Extra Information: Exposure is also the amount of ionization that is produced by the radiation. It is defined as the amount of ionization produced in a unit mass of dry air at standard temperature and pressure (STP), 1 atmosphere and 0°C. 1 Roentgen = 1 R = 2.58 x 10 -4 coulombs per kilogram = 1 coulomb per cc of dry air Applicable to ionizing radiation up to 3 MeV
  • Again, the concept is important, but not the units. 1 roentgen exposure to X rays or gamma rays produces a soft tissue absorbed dose of approximately 1 rad. Extra Information: Applicable to ionizing radiation up to 3 MeV
  • Note that Rems are used in the US, Sieverts in Europe. 1 rem = 1 rad x QF R 1 Sv = 1 Gy x QF G = 100 rem QF R and QF G are different for different types of radiation QF R for x-rays, γ rays and β is 1; for α is 20; for n is 5-20 (based on n energy)
  • Good slide, but less according to previous slides.
  • This slide is for reference, mainly as a handout. It simply details the conversions between Rems, millirems and microrems

Transcript

  • 1. Basic RadiationAnimations in this training work best in Windows XP May 2006
  • 2. Topics• Introduction to Radiation• Types of Radiation• How Radiation Interacts with the Environment• Radiation Safety• Why We Need to Measure Radiation Today
  • 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. 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. 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. Topics• Introduction to Radiation• Types of Radiation• How Radiation Interacts with the Environment• Radiation Safety• Why We Need to Measure Radiation Today
  • 7. Types of Radiation
  • 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. 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. 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. 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. 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. 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. 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. 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. 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. 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. Topics• Introduction to Radiation• Types of Radiation• How Radiation Interacts with the Environment• Radiation Safety• Why We Need to Measure Radiation Today
  • 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. Topics• Introduction to Radiation• Types of Radiation• How Radiation Interacts with the Environment• Radiation Safety• Why We Need to Measure Radiation Today
  • 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. 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. 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. 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. 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. Water,Shielding/Attenuating Radiation Polyethylene Lead, Concrete Glass, thin metal Paper α β γ η
  • 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. 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. 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. 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. 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. 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. 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. Topics• Introduction to Radiation• Types of Radiation• How Radiation Interacts with the Environment• Radiation Safety• Why We Need to Measure Radiation Today
  • 35. Why Detect Radiation Today?• Medicine – Imaging – Cancer treatment and therapy• Industrial – Imaging – Gauges• Power• Agriculture• Radiological terrorism
  • 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. 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. Threat Comparison Stolen nuclear weapon ImprovisedSeverity of incident nuclear device RDD Probability of incident
  • 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. 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. 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. 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. Threats
  • 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. “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. 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. Questions?www.raesystems.comelang@raesystems.com
  • 48. Additional Slides• Additional Slides
  • 49. Mishaps
  • 50. Mishaps
  • 51. Terrorist Attacks
  • 52. RDDs
  • 53. RDDs
  • 54. RDDs
  • 55. Material Attacks
  • 56. Material Theft
  • 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. 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. 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. 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. 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. 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. 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. 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. 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. Radioactive Contamination• Radiation cannot make you radioactive* * Understanding Radiation: Bjorn Wahlstrom
  • 67. Radioactive Contamination• Radioactive contamination can stick to clothes & skin. It can be washed away like any dirt*. * Understanding Radiation: Bjorn Wahlstrom
  • 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