Principles of Radiation Industrial Studies 4020 Topics in Industrial Studies Environmental Safety Management Review • Atomic number Atomic mass Number of Protons ONLY Number of Protons & Neutrons (weight) Atomic Mass 14 Chemical Symbol 12 C Atomic Number So, what is it ? 3 Hydrogen – 3 contains one proton + two neutrons. It’s a radioactive isotope of hydrogen also known as tritium Isotopes • Same number of protons; different number of neutrons • Same chemical properties • Different nuclear properties 1 2 3 1H 1 H 1H Hydrogen * Tritium Deuterium 1 Proton, 2 Neutrons 1 Proton 1 Proton, 1 Neutron * Note: Tritium is Radioactive Radioactivity • Atoms with too many neutrons or protons are unstable and emit energy to become more stable. • Energy is carried away by a- / b-particle or x- / g-ray. • These atoms are called radioactive and the process is called radioactive decay Radioactivity Man made • Natural Phosphorus-32 (P-32) – Uranium Sulfur-35 (S-35) – Thorium Calcium-45 (Ca-45) – Potassium-40 Chromium-51 (Cr-51) Zinc-65 (Zn-65) – Carbon-14 (C-14) Rubidium-86 (Rb-86) – Hydrogen-3 (H-3) (tritium) Iodine-125 (I-125) Background Radiation mrem/yr Cosmic 27 Terrestrial 28 Inhaled 200 Internal 39 Man-made 63 Total: 357 Radiation Emission / propagation of Microwave light bulb energy through space or cell phone UV lamp material medium as waves or radio / TV laser particles heat lamp x-rays Ionizing Radiation Alpha Particles 2 Protons + 2 Neutrons Short Range in Air Not an External Hazard Internal Hazard Beta Particles Negligible Mass Long Range in Air Internal/External Hazard Charged Gamma Rays/Photons Gamma photons & X-Ray both electromagnetic differ only by place of origin No mass or charge Highly-penetrating Neutrons Very Long Range Very Penetrating Difficult to detect Other modes of Decay •Positron emission •Electron capture •Fission •Electron Activity • Decay is a statistical process. – Cannot predict when a particular atom will decay. – Can predict when certain amount (%) will have decayed. Units of Activity Curie (Ci) – 1 Ci = 37,000,000,000 dps (3.7 x 1010 dps) or 1 Ci = 2.22 x 1012 dpm Becquerel (Bq) – 1 Bq = 1 dps – 1 Ci = 37,000,000,000 Bq = 37 GBq (Giga Becquerel) Quantities & Units • Beta and gamma radiation about equally damaging: 1 R = 1 rad = 1 rem • Alpha radiation causes greater cellular damage 1 rad of a = 20 rem Decay Rate Half-life, A= A0 e 0.693t/T½ A = A0 (½)# of half-lives Non-Ionizing Radiation Questions? Radiation Safety Industrial Studies 4020 Topics in Industrial Studies Environmental Safety Management Radiation Hazards • External Hazard (exposure from outside the body) – High-energy beta (i.e., energy > 300 keV or > 0.3 MeV) – Gamma and X-rays – Neutrons • Internal Hazard – Radioactive material enters body by eating/drinking in radiation area, by breathing vapors/aerosols, or skin absorption – In body, it is treated like non-radioactive elements • If not incorporated into organ, rapidly excreted and may pose only slight hazard • If stored in organ, slowly excreted (effective half-life) Acute Biological Effects Whole body, external acute exposure effects 25 rad some chromosome aberrations 50 rad minor blood changes 100 rad 2% radiation sickness 400 rad 50% die in 60 days (LD50/60) 700 rad lethal single exposure 6000 rad cancer therapy (local) Low Dose Biological Effects ALARA As Low As Reasonably Achievable Benefits outweigh risks? Lower Dose = Lower Risk Monitoring Workers • Whole body badge (TLD) • Collar or Ring TLD • Bioassay -- thyroid (iodine) • urinalysis (tritium) Occupational Exposure Limits Accumulated Dose Not to Exceed Equivalent to: mrem/yr rem/yr mSv/yr Whole Body 5,000 5 50 Lens of the Eye 15,000 15 150 Skin of Whole Body 50,000 50 500 Extremities of Whole 50,000 50 500 Body -- Hands, Feet, etc General Safety Measures • TIME • DISTANCE Exposure increases with time Exposure decreases with distance v • SHIELDING Plastic for beta Lead for gamma Time vs Exposure Increased exposure (risk) over time Linear 3 mR/hr * 4 hr = ??? Distance vs Exposure 2 I1d1 = I2d2 2 Exposure & Shielding No shielding needed for alpha or low-energy beta Thick, dense (i.e., lead) for gamma / x-rays Plastic beta Hydrogeneous (or boron + cadmium) for neutrons Detectors/ Monitors Detectors/ Monitors 1) Capable of Detecting 2) Efficiency 3) Calibration Industrial Uses of Radiation http://www.epa.gov/rpdweb00/source-reduction-management/applications.html Industrial Uses of Radiation Lasers X-rays Gauges Wireless exit signs X-ray Fluorescence (XRF) Industrial Uses of Radiation Moisture/density gauges Radiography Static control Smoke detectors http://www.epa.gov/rpdweb00/source-reduction-management/applications.html Emergency Response • Lifesaving and serious injury take precedence over radiation exposure and contamination • Control Access to Area • Call for Help Radioactive Waste Industrial Studies 4020 Topics in Industrial Studies Environmental Safety Management Types of Radioactive Waste Spent Fuel - Withdrawn from a nuclear reactor following irradiation High-level waste - Highly radioactive material from reprocessing spent nuclear fuel Transuranic - Man-made elements above atomic number 92 Types of Radioactive Waste NORM – Naturally-occurring radioactive material (primarily uranium & thorium Special Nuclear - Pu, U-233, or uranium enriched in the Material isotopes U-233 or U-235 Low-level waste - not high-level radioactive waste, spent nuclear fuel, transuranic waste, or certain by-product material Solid Waste • Landfill • Decay • Incinerate • Supercompaction LSC Vial Waste • Aqueous Waste • Hold for decay • Sanitary sewer Table II POTW • Mixed Waste • RCRA/AEA – Dual regulation • EPA/State Conditional exemption • Department of Energy Questions?
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