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Radiation and Radioactivity: Units and Quantities

Radiation and Radioactivity: Units and Quantities. Introduction. Quantities (mass, volume, time, etc.) vs. Units (grams, gallons, hours) Units of exposure, radioactivity, and energy associated with ionizing radioactivity As hours and minutes are to time. Objectives. Define

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Radiation and Radioactivity: Units and Quantities

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  1. Radiation and Radioactivity: Units and Quantities www.assignmentpoint.com

  2. Introduction • Quantities (mass, volume, time, etc.) vs. Units (grams, gallons, hours) • Units of exposure, radioactivity, and energy associated with ionizing radioactivity • As hours and minutes are to time ... www.assignmentpoint.com

  3. Objectives • Define • ROENTGEN, RAD, REM, CURIE, GRAY, SIEVERT, BECQUEREL. • SI units vs. Standard English units • Discuss the use and conversion of unit prefixes • Transform units using “unit analysis” www.assignmentpoint.com

  4. Background • Early risk associated with use of ionizing radiation • skin erythema dose - 25yrs • 1928 - ROENTGEN introduced by ICRP www.assignmentpoint.com

  5. Roentgen www.assignmentpoint.com

  6. Roentgen • Named after Wilhelm C. Roentgen • (thus the abbr... is capital “R”) • Pronounced rent’gen with a hard “g” • Limitations • only applies to photons • only applies in air • only applies to energies less than 3 MeV www.assignmentpoint.com

  7. rad www.assignmentpoint.com

  8. rad • 1 rad = 1 Roentgen www.assignmentpoint.com

  9. rem www.assignmentpoint.com

  10. rem • Roentgen Equivalent Man • The unit of dose equivalent for any type of ionizing radiation absorbed by body tissue in terms of estimated biological effect - Unit of dose equivalent • Dose in health record is in units of rem • 1 rem = 1 Roentgen www.assignmentpoint.com

  11. Quality Factor (Q) The specific value that accounts for the ability of different types of ionizing radiation to cause varying degrees of biological damage • X-rays, gamma rays, & beta particles 1 • Neutrons & High energy protons 10 • Alpha Particles 20 www.assignmentpoint.com

  12. Curie (Ci) • Radiation hazard does not solely depend on the activity. It also depends on the type of decay (alpha, beta, photon, etc.) • Named in honor of Pierre Curie www.assignmentpoint.com

  13. SI Radiation Protection Units • Becquerel (Bq) for Curie • 1 Ci = 3.7 x 1010 Bq • Gray (Gy) for rad • 1 Gy = 100 rad • Sievert (Sv) for rem • 1 Sv = 100 rem www.assignmentpoint.com

  14. Unit Analysis BASE UNIT CONVERSION TABLE Unit Unit Conversion 1 Bq 2.7 x 10-11 Ci 1 Ci 3.7 x 1010 Bq 1 Bq 1 dis/sec 1 dis/sec 2.7 x 10-11 Ci 1 Ci 3.7 x 1010 dis/sec www.assignmentpoint.com

  15. Unit Analysis (Con’t.) BASE UNIT CONVERSION TABLE Unit Unit Conversion 1 rem 0.01 Sv 1 Sv 100 rem 1 rad 0.01 Gy 1 Gy 100 rad 1 R 2.58 x 10-4 C/kg 1 meter 3.28 ft (39.37in) www.assignmentpoint.com

  16. Summary • Radiation Protection unit definitions (including SI units) • Unit Prefixes • Unit conversions www.assignmentpoint.com

  17. Old Terms • Roentgen-Based on the quantity of electrical charges produced in air by X or Gamma photons 1R=2 billion pr • RAD-Radiation Absorbed Dose is the work energy resulting from the absorption of one ROENTGEN or 6.24 E5 Mev www.assignmentpoint.com

  18. More Old Terms • REM-Roentgen Equivalent Mammal is equal to the absorbed does in RADS multiplied by a quality factor • Quality Factors • Beta = 1 • Gamma & X ray photons = 1 • Alpha = 10 • Neutrons = 20 www.assignmentpoint.com

  19. New Terms sort of International Units have replaced the RAD and REM GRAY (Gy) = 100 RAD SIEVERT (Sv) = 100 REM Same Quality Factors apply to the Sv www.assignmentpoint.com

  20. Units of Radioactivity • Curie (Ci) = 2.22 E12 dpm or 3.7E10 dps • Becquerel (Bq) = 1 dps • Maximum Dose/year = 5 REM or 50 mSv • Maximum Dose/year for Declared Pregnant Woman & Minors= 0.5 REM or 5 mSv www.assignmentpoint.com

  21. Half Life Calculation www.assignmentpoint.com

  22. Adult ($18 yrs) Minor (< 18 yrs) Whole body* 5000 mrem/yr 500 mrem/yr Lens of eye 15000 mrem/yr 1500 mrem/yr Extremities 50000 mrem/yr 5000 mrem/yr Skin 50000 mrem/yr 5000 mrem/yr Organ 50000 mrem/yr 5000 mrem/yr Annual Dose Limits External/Internal Exposure Limits for Occupationally Exposed Individuals www.assignmentpoint.com • *Effective dose equivalent

  23. Dose Response Relationships • 0-150 rem—No or minimal symptoms • 150-400 rem—Moderate to severe illness • 400-800 rem—Severe illness deaths start above 500 rem • Above 800 rem—Fatal ***Acute whole body doses www.assignmentpoint.com

  24. Activity Typical Dose Smoking 280 millirem/year Radioactive materials use in a UM lab <10 millirem/year Dental x-ray 10 millirem per x-ray Chest x-ray  8 millirem per x-ray Drinking water  5 millirem/year Cross country round trip by air  5 millirem per trip  Coal Burning power plant 0.165 millirem/year  Your Annual Exposure www.assignmentpoint.com

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  27. Estimated Exposure To The National Population • Between 320 – 360 mr/yr www.assignmentpoint.com

  28. Another Look at Sources www.assignmentpoint.com

  29. Some Exposure Limits • 2 mr/hr Dose rate to public / Federal • 500 mr Emergency responder limit / State/BRC • 5 r/yr Occupational /Federal • 5 r/hr Turn back value / State/BRC • 10 r Property / Federal • 25 r Life saving / Federal • >25r Volunteers only / Federal Ref - 10CFR PART 20, EPA 400, FL-SOP www.assignmentpoint.com

  30. Security • All Radioactive Materials must be secured or under direct supervision at all times • There MUST be someone in the room at all times OR the door must be locked. www.assignmentpoint.com

  31. Spill Response • On Skin—flush completely • On Clothing—remove • If Injury—administer first aid • Radioactive Gas Release—vacate area, shut off fans, post warning • Monitor all persons and define the area of contamination www.assignmentpoint.com

  32. ALARA As Low As Reasonably Achievable—means making every reasonable effort to maintain exposures to radiation as far below the dose limits as is practicable consistent with the purpose for which the licensed activity is undertaken, taking into account the state of technology, the economics of improvements in relation to the state of technology, the economics of improvements in relation to benefits to the public health and safety, and other societal and socioeconomic considerations, and in relation to utilization of nuclear energy and licensed materials in the public interest. www.assignmentpoint.com

  33. Radiation Protection • Decrease Time • Increase Distance • Increase Shielding www.assignmentpoint.com

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