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Fundamental Principles of Radiation

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Fundamental Principles of Radiation Kathryn Gladden Environmental Monitoring Programs Nevada Site Specific Advisory Board (NSSAB) Educational Session November 9, 2016 Fundamentals of Ionizing Radiation 11/9/2016 – Page 2 PageLog 2Title No. 2012Page-248 2 What is an Atom? 11/9/2016 – Page 3 PageLog 3Title No. 2012Page-248 3 Atoms Atoms are the building blocks of ALL matter - + + N N - A Helium atom is used in this example 11/9/2016 – Page 4 PageLog 4Title No. 2012Page-248 4 Nucleons Proton Neutron Mass is about 1 amu Mass is about 1 amu 1 Atomic Mass Unit (amu) = 1.66 x 10-24 gram Mass is about 0.0005 amu 11/9/2016 – Page 5 PageLog 5Title No. 2012Page-248 5 Atoms • Nuclear particles form atoms • Similar atoms combine to form elements • Elements combine to form molecules • Molecules combine to form compounds 11/9/2016 – Page 6 PageLog 6Title No. 2012Page-248 6 Isotopes • The number of PROTONS defines the ELEMENT • The number of NEUTRONS defines the ISOTOPE • The isotopes of an element have similar chemical properties but different nuclear properties – Some isotopes are stable – Some isotopes are radioactive 11/9/2016 – Page 7 PageLog 7Title No. 2012Page-248 7 Isotopes Different Isotopes of Hydrogen “Normal” Hydrogen Deuterium Tritium or Protium 1 proton 1 proton 1 proton 1 neutron 2 neutrons 0 neutron 1 electron 1 electron 2 3 1 electron 1 H 1 H 1 1 H - - - + + + N N N 11/9/2016 – Page 8 PageLog 8Title No. 2012Page-248 8 Isotopes and Atomic Notation X = The symbol of the element A Z = The atomic number (# of protons) Z X A = The atomic mass number (# of protons + neutrons) Different Isotopes of Hydrogen “Normal” Hydrogen or Protium Deuterium Tritium 1 proton 1 proton 1 proton 0 neutrons 1 neutron 2 neutrons 1 electron 1 electron 1 electron 1 2 3 1 H 1 H 1 H - - - + + + N N N 11/9/2016 – Page 9 PageLog 9Title No. 2012Page-248 9 Ionizing Radiation 11/9/2016 – Page 10 PageLog 10Title No. 2012Page-248 10 Two Types of Radiation • Non-Ionizing • Ionizing 11/9/2016 – Page 11 PageLog 11Title No. 2012Page-248 11 Non-Ionizing Radiation that doesn’t have enough energy to form ions: • Radar Waves • Microwaves • Laser • Visible Light 11/9/2016 – Page 12 PageLog 12Title No. 2012Page-248 12 Electromagnetic Spectrum The Electromagnetic Spectrum is a large family of radiation that includes light, infrared, ultraviolet, X-rays, radio waves, and gamma rays 11/9/2016 – Page 13 PageLog 13Title No. 2012Page-248 13 Ionizing Radiation Excess energy (from unstable atoms) capable of removing orbiting electrons from an atom, producing electrically- charged particles called ions. The “free” electron (- charge) and the remaining atom (+ charge) are the ions. 11/9/2016 – Page 14 PageLog 14Title No. 2012Page-248 14 Stability of Nucleus Alpha (α) Beta (β) Gamma (γ) 11/9/2016 – Page 15 PageLog 15Title No. 2012Page-248 15 Alpha Particle Radiation 11/9/2016 – Page 16 PageLog 16Title No. 2012Page-248 16 Alpha Particle Radiation (continued) Alpha • Large, highly positive charged particle • Range in air about 1 - 2 inches • Shielding can be a piece of paper, clothing or even the dead outer layer of skin • Biological hazard is inhalation or ingestion 11/9/2016 – Page 17 PageLog 17Title No. 2012Page-248 17 Beta Particle Radiation 11/9/2016 – Page 18 PageLog 18Title No. 2012Page-248 18 Beta Particle Radiation (continued) Beta • Small, negative charged particle • Range in air is about 10 feet • Shielding can be plastic, glass, metal foil, or safety glasses • Biological hazard is inhalation or ingestion • Externally, the eyes and skin are at risk 11/9/2016 – Page 19 PageLog 19Title No. 2012Page-248 19 Gamma-Ray Radiation 11/9/2016 – Page 20 PageLog 20Title No. 2012Page-248 20 Gamma-Ray Radiation (continued) Gamma • Electromagnetic waves or photons that have no charge, similar to X-rays • Range in air is several hundred feet • Shielding is more difficult due to high penetrating power - dense materials (high Z number) such as concrete, lead, steel • Biological hazard is whole body 11/9/2016 – Page 21 PageLog 21Title No. 2012Page-248 21 Neutron Radiation 11/9/2016 – Page 22 PageLog 22Title No. 2012Page-248 22 Neutron Radiation (continued) Neutron • Neutral particle ejected from nucleus • Range in air is several hundred feet • Shielding is better with materials that have high hydrogen content - water, plastic, boron, and even paraffin (low Z number) • Biological hazard is whole body due to high penetrating power 11/9/2016 – Page 23 PageLog 23Title No. 2012Page-248 23 Radioactivity Radioactivity is a natural and spontaneous process by which unstable radioactive atoms decay to a different state and emit excess energy in the form of radiation Half-life (T½) is the amount of time required for radioactive material to decrease by one half; each radioisotope has a unique Half-life time period 11/9/2016 – Page 24 PageLog 24Title No. 2012Page-248 24 Units of Measure 11/9/2016 – Page 25 PageLog 25Title No. 2012Page-248 25 Units for Radiation Dose and Exposure Roentgen (R) Unit for measuring exposure Defined only for effect on air Applies only to gamma and X-ray radiation Does not relate biological effects of radiation to the human body 11/9/2016 – Page 26 PageLog 26Title No. 2012Page-248 26 Units for Radiation Dose and Exposure (continued) Rad (Radiation Absorbed Dose) Unit for measuring absorbed dose in any material Defined for any material Applies to all types of radiation Does not take into account the potential effect that different types of radiation have on the body 11/9/2016 – Page 27 PageLog 27Title No. 2012Page-248 27 Units for Radiation Dose and Exposure (continued) Rem (Roentgen Equivalent Man) Unit for measuring effective dose (most commonly used unit) Pertains to human body Applies to all types of radiation Takes into account the energy absorbed (dose) and the biological effect on the body due to the different types of radiation 11/9/2016 – Page 28 PageLog 28Title No. 2012Page-248 28 Units for Radiation Dose and Exposure (continued) Rad Rem Roentgen (R) (Radiation Absorbed Dose) (Roentgen Equivalent Man) Unit for measuring exposure Unit for measuring absorbed Unit for measuring dose dose in any material equivalence (most commonly used unit) Defined only for effect on air Defined for any material Pertains to human body Applies only to gamma and Applies to all types of Applies to all types of X-ray radiation radiation radiation Does not relate biological Does not take into account Takes into account the effects of radiation to the the potential effect that energy absorbed (dose) and human body different types of radiation the biological effect on the have on the body body due to the different types of radiation Rem = Rad x WF 11/9/2016 – Page 29 PageLog 29Title No. 2012Page-248 29 Not All Radiation is the Same • Different radiation has different biological effects • Radiation WEIGHTING FACTORS Alpha = 20 α Neutron = 5 - 20 η Beta = 1 β Gamma = 1 γ 11/9/2016 – Page 30 PageLog 30Title No. 2012Page-248 30 Prefixes for Units 1 rem = 1,000 mrem (millirem) 1 mrem = 1,000 µrem (microrem) The same holds true for the new SI units, i.e., 1 Sievert (Sv) = 1,000 mSv (millisieverts) 1 mSv = 1,000 µSv (microsieverts) 11/9/2016 – Page 31 PageLog 31Title No. 2012Page-248 31 Unit Conversions Source Activity (disintegrations per Exposure Dose unit time) Old Units Curie (Ci) = 37x109 dps Roentgen (R) Rem-roentgen dps = disintegrations per RAD or rad: equivalent man second radiation absorbed dose New SI Units Becquerel (Bq) Gray (Gy) Sievert (Sv) 1 Bq – 1 dps 1 Gy – 100 rad 1 Sv – 100 rem 1 Ci – 37 GBq 1 rad – 1 cGy 1 rem – 10 mSv For gamma and x-ray radiation, a common “conversion factor” between exposure, absorbed dose, and dose equivalent is: 1 R = 1 rad = 1 rem 11/9/2016 – Page 32 PageLog 32Title No. 2012Page-248 32 Sources of Radiation 11/9/2016 – Page 33 PageLog 33Title No. 2012Page-248 33 Natural Sources of Radiation • Cosmic radiation • Terrestrial radiation • Radon • Human body 11/9/2016 – Page 34 PageLog 34Title No. 2012Page-248 34 Man-made Sources of Radiation • Medical radiation • Nuclear Power • Consumer products • Industry and Research • Other minor sources 11/9/2016 – Page 35 PageLog 35Title No. 2012Page-248 35 Average Doses from Radiation Sources • Average person in the U.S. receives about 620 mrem each year – Natural sources = 310 mrem – Medical procedures and consumer products = 310 mrem Unaltered information taken from the 2015 NNSS Environmental Report 11/9/2016 – Page 36 PageLog 36Title No. 2012Page-248 36 Sources of Radiation Exposure Unaltered information taken from the 2015 NNSS Environmental Report 11/9/2016 – Page 37 PageLog 37Title No. 2012Page-248 37 Biological Effects of Radiation Exposure 11/9/2016 – Page 38 PageLog 38Title No. 2012Page-248 38 Exposure to radiation will cause none of these things to happen You will not get super powers You will not turn green Radiation does not cause things to grow larger You will not glow in the dark 11/9/2016 – Page 39 PageLog 39Title No. 2012Page-248 39 Two Categories of Radiation Dose • Acute • Chronic 11/9/2016 – Page 40 PageLog 40Title No. 2012Page-248 40 Acute Radiation Doses • An acute effect is a physical reaction due to massive cell damage • Damage caused by a large amount of radiation in a short period of time 11/9/2016 – Page 41 PageLog 41Title No. 2012Page-248 41 Acute Radiation Dose Effects Blood changes 25 – 100 Rad Anorexia (loss of appetite) 150 Rad Nausea 200 Rad Fatigue 220 Rad Vomiting 280 Rad Epilation 300 Rad Diarrhea 350 Rad Mortality (w/o supportive care) 350 Rad Mortality (with supportive care) 500 Rad 11/9/2016 – Page 42 PageLog 42Title No.
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