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This document provides an overview of radiation safety training at MIT. It defines key terms like radiation, radioactivity, units of activity, and half-life. It describes the types of radiation (alpha, beta, gamma), their properties, and methods of shielding. It discusses regulations, responsibilities, biological effects, and dose limits. The training emphasizes principles of radiation safety like ALARA and outlines protocols for handling sealed sources, transportation, and experimental setups. Workers are instructed to contact the Radiation Protection Program with any radiation safety questions or concerns.

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Radioactive Materials Safety Training Massachusetts Institute of Technology Radiation Protection Program William B. McCarthy, Ph.D., CHP wbm@mit.edu x3-0346

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Outline 1. Introduction 2. Delegation of Authority 3. Radiation Physics 4. Units and Quantities 5. Background and Occupational Radiation Doses 6. Biological Effects of Ionizing Radiation 7. Minimizing Radiation Exposures - ALARA 8. General Radiation Safety and Surveys

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Purpose • Provide for the protection of the Institute population, general public, and environment against radiation hazards associated with MIT's possession, use, transportation, and disposal of radioactive material. • Provide for the Institute's compliance with MDPH and other applicable radiation protection regulations.

4

Massachusetts DPH Radiation Control Program • MDPH 105 CMR 120.750, “Notices Instructions and Reports to Workers: Inspections.” – Your Rights as a Radiation Worker • MDPH 105 CMR 120.200, “Standards for Protection Against Radiation.” • License/Registration - includes special conditions. • State inspects every two years as well as surprise inspections.

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Responsibility Radiation Protection Program x3-2180 Individual Radiation worker Project Supervisor/ Principle Investigator MIT Radiation Protection Committee President, MIT

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Radiation • Radiation: Energy in the form of particles or electromagnetic waves • Ionizing Radiation: Radiation with sufficient energy to remove an electron from an atom or molecule.

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Radioactivity • The process by which unstable atoms spontaneously transform to new atoms* and in the process emit radiation. $- * The “new atom” may be the same atom in a lower energy state.

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Units of Activity • Curie (Ci): 37 Billion transformations per second. (2.22 trillion per minute) • Bequerel (Bq): 1 transformation per second. mCi and uCi are common quantities used in the lab (10 uCi up to 50 mCi). 0.0013 uCi (48 Bq) - Ra-226 in a 1 kg rock 0.12 uCi (4400 Bq) - K-40 in your body 330 pCi - C-14 in ¼ lb of beef

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Half-Life • Half-life is the amount of time needed for the activity to reach one half of the original amount. f 1 2 t T1/2 f e l t l ln ( ) 2 T1/2 0 20 40 60 80 100 0.00 0.20 0.40 0.60 0.80 1.00 One half-life Two half-lives 0.007 Days

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Definitions • Exposure R (roentgen): Amount of charge produced per unit mass of air from x-rays and gamma rays. • Absorbed Dose rad: Amount of Energy deposited per unit mass of material. 1Gy = 100 rad. • Dose Equivalent rem: Risk adjusted absorbed dose. The absorbed dose is weighted by the radiation type and tissue susceptibility to biological damage. 1 Sv = 100 rem. • Radiation weighting factors: alpha(20), beta(1), n(10). • Tissue weighting factors: lung(0.12), thyroid(0.03), and gonads(0.25). For whole body x or gamma-ray exposure 1 R  1 rad  1 rem

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Alpha Decay • Helium Nucleus – Very massive and doubly ionized • Only a hazard via ingestion or inhalation of alpha emitter • Not usually an external radiation hazard • Stopped by paper and dead layer of skin • Uranium, Thorium, Radon and radon daughters

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Beta Decay • Energetic electron – singly ionized • External hazard to skin and eyes • Internal hazard via ingestion or inhalation of beta emitter • Produces bremsstrahlung radiation • A 1 MeV beta can travel up to 12 feet in air and 1 cm in plastic • Phosphorus, Tritium, Carbon, Sulfur

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Gamma Decay • X-rays and gamma rays are photons – no charge • External radiation hazard to deep organs and tissues • Internal hazard via ingestion or inhalation of gamma emitter • Lead (high electron density) is good for shielding x and gamma rays • Iodine 125 gammas (30 keV) can be easily stopped with 1/8 inch of lead

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paper plastic lead alpha particle beta particle gamma ray x-ray e- e- e- He++ photon Neutron shielding material depends on the energy of the neutrons

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Bremsstrahlung X-Rays • Bremsstrahlung x-ray intensity increases with increasing atomic number of absorber, and the average x-ray energy increases with increasing electron energy. (activity of the source is also a factor) x-ray e- plastic lead electrons

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Shielding for beta emitting material 90Sr plastic lead

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Low energy gamma or x-ray High energy gamma or x-ray Shielding for gamma emitting material

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Typical background is 0.03 mR/hr or 100 cpm GM pancake probe NaI probe Range selector Battery check

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Sources of Average Radiation Dose to the U.S. Population Radon, 200 55% Internal, 39 10% Terrestrial, 28 8% Cosmic, 27 8% Nuclear Medicine, 14 4% Medical x-rays, 39 11% Consumer Products, 10 3% Other, 3 0.8% Source: BEIR V Report, 1990 Background Radiation 360 millirem per year

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Annual Occupational Dose Limits Whole Body 5,000 mrem/year Lens of the eye 15,000 mrem/year Extremities, skin, and individual tissues 50,000 mrem per year Minors 500 mrem per year (10%) Embryo/fetus* 500 mrem per 9 months General Public 100 mrem per year * Declared Pregnant Woman

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Biological Effects • Many groups exposed to ionizing radiation at high levels resulted in adverse effects. • Somatic effects – Prompt - skin burns and cataracts – Delayed - cancer • Genetic effects • Teratogenetic effects

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X-Ray Burns 5,000+ rad 500+ rad P-32 - 6.5 rad/hr/uCi S-35 - 2.5 rad/hr/uCi

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Cancer • Radiation can damage cells through two methods; – Production of free radicals and – Direct damage to the DNA. • Risk factor for radiation dose: – 4% increase in risk of dying of cancer for every 100 rem of dose. – Normal cancer risk is 20%.

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0 10 20 30 40 50 60 70 Committed Lifetime Dose (rem) 0.00 0.01 0.02 0.03 Risk of death from cancer Dose Response Relationship Predictable Effects Risk Is not Predictable below 20 rem Effect is Detrimental risk level is uncertain Occupational dose – above background

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ALARA • ALARA - As Low As Reasonably Achievable • Time • Distance (inverse square law) • Shielding • Contamination Control

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Inverse Square Law 5 mrem/hr @ 10 cm 50,000 mrem/hr @ 0.1 cm 45 mrem/hr @ 3.3 cm D2 . D1 x1 x2 2 D - Dose x - distance

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Radioactive Sealed Sources • Sealed sources used as a source of radiation – Alpha particles – Beta particles – Gamma ray – Bremsstrahlung – Neutron sources • Permanently enclosed in either a capsule or another suitable container designed to prevent leakage or escape of the radioactive material • Inventory and Use records are required

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• Tested for surface contamination and leakage – Sources may leak radioactive material – Tested usually once every 6 months for beta & gamma emitters that are > 100 uCi – Tested every 3 months for alpha emitters > 10 uCi – Allowable limit is less than 0.005 uCi • A leaking source shall immediately be removed from use – Action to be taken to prevent contamination – Source to be repaired or disposed of • RPP has a shielded storage facility for sources that are not in use. Radioactive Sealed Sources

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Security and Transportation • All radiation sources must be kept locked up when not in use. • Experiments left unattended should be labeled “Experiment in Progress.” • An up-to-date use log of all sources must be kept at the storage location. • All radiation laboratories will be locked when unattended for extended periods. • When you are the means for security, you must challenge unknown persons entering the lab. • Sources can only be used in a registered radiation laboratory. • Call RPP for all transfers of sources to other authorizations.

30

General Radiation Safety • No food or beverages in the lab • Keep a survey meter conveniently close by • ALARA - time, distance, and shielding • Label radioactive materials and equipment • Never remove sources from the Jr Physics Lab

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Experimental Setups Moessbauer Spectroscopy • 10 mCi 57Co source (122 keV gamma) • Exposure Rates – 9000 mR/hr at 1 cm – ~1 mR/hr at 3 feet • With shielding – Background levels E/M experiment • 10 mCi 90Sr/Y (b) and 110 uCi 133Ba (g) source • Exposure Rates • 90Sr/Y - skin • 9000 mrad/hr to skin • 133Ba – whole body • 2.6 mR/hr at 10 cm

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Experimental Setups cont… Alpha Decay • Natural U, Th, and Ra in rocks • Exposure Rates – 0.1 mR/hr at 1 foot – Contact 3mR/hr - gamma – Contact 35 mrad/hr - beta Compton Scattering • 500 uCi 137Cs source • Beta and gamma emitter • Exposure Rates • 1.5 mR/hr at opening • 0.15 mR/hr on contact with lead • Background levels in area

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Experimental Setups cont… Rutherford Scattering • 165 uCi 241Am source • Alpha and gamma emitter • Alpha 5.5 MeV • Gamma ~ 60 keV • Many smoke detectors have 1 uCi of 241Am

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When do you contact RPP? • Missing radioactive material • Suspected leaking source • Suspected accidental exposure • Questions or concerns • Call x2-3477 between 9am-5pm or x100 any time

More Related Content

wbm-slides-f04.ppt

  • 1. Radioactive Materials Safety Training Massachusetts Institute of Technology Radiation Protection Program William B. McCarthy, Ph.D., CHP wbm@mit.edu x3-0346
  • 2. Outline 1. Introduction 2. Delegation of Authority 3. Radiation Physics 4. Units and Quantities 5. Background and Occupational Radiation Doses 6. Biological Effects of Ionizing Radiation 7. Minimizing Radiation Exposures - ALARA 8. General Radiation Safety and Surveys
  • 3. Purpose • Provide for the protection of the Institute population, general public, and environment against radiation hazards associated with MIT's possession, use, transportation, and disposal of radioactive material. • Provide for the Institute's compliance with MDPH and other applicable radiation protection regulations.
  • 4. Massachusetts DPH Radiation Control Program • MDPH 105 CMR 120.750, “Notices Instructions and Reports to Workers: Inspections.” – Your Rights as a Radiation Worker • MDPH 105 CMR 120.200, “Standards for Protection Against Radiation.” • License/Registration - includes special conditions. • State inspects every two years as well as surprise inspections.
  • 5. Responsibility Radiation Protection Program x3-2180 Individual Radiation worker Project Supervisor/ Principle Investigator MIT Radiation Protection Committee President, MIT
  • 6. Radiation • Radiation: Energy in the form of particles or electromagnetic waves • Ionizing Radiation: Radiation with sufficient energy to remove an electron from an atom or molecule.
  • 7. Radioactivity • The process by which unstable atoms spontaneously transform to new atoms* and in the process emit radiation. $- * The “new atom” may be the same atom in a lower energy state.
  • 8. Units of Activity • Curie (Ci): 37 Billion transformations per second. (2.22 trillion per minute) • Bequerel (Bq): 1 transformation per second. mCi and uCi are common quantities used in the lab (10 uCi up to 50 mCi). 0.0013 uCi (48 Bq) - Ra-226 in a 1 kg rock 0.12 uCi (4400 Bq) - K-40 in your body 330 pCi - C-14 in ¼ lb of beef
  • 9. Half-Life • Half-life is the amount of time needed for the activity to reach one half of the original amount. f 1 2 t T1/2 f e l t l ln ( ) 2 T1/2 0 20 40 60 80 100 0.00 0.20 0.40 0.60 0.80 1.00 One half-life Two half-lives 0.007 Days
  • 10. Definitions • Exposure R (roentgen): Amount of charge produced per unit mass of air from x-rays and gamma rays. • Absorbed Dose rad: Amount of Energy deposited per unit mass of material. 1Gy = 100 rad. • Dose Equivalent rem: Risk adjusted absorbed dose. The absorbed dose is weighted by the radiation type and tissue susceptibility to biological damage. 1 Sv = 100 rem. • Radiation weighting factors: alpha(20), beta(1), n(10). • Tissue weighting factors: lung(0.12), thyroid(0.03), and gonads(0.25). For whole body x or gamma-ray exposure 1 R  1 rad  1 rem
  • 11. Alpha Decay • Helium Nucleus – Very massive and doubly ionized • Only a hazard via ingestion or inhalation of alpha emitter • Not usually an external radiation hazard • Stopped by paper and dead layer of skin • Uranium, Thorium, Radon and radon daughters
  • 12. Beta Decay • Energetic electron – singly ionized • External hazard to skin and eyes • Internal hazard via ingestion or inhalation of beta emitter • Produces bremsstrahlung radiation • A 1 MeV beta can travel up to 12 feet in air and 1 cm in plastic • Phosphorus, Tritium, Carbon, Sulfur
  • 13. Gamma Decay • X-rays and gamma rays are photons – no charge • External radiation hazard to deep organs and tissues • Internal hazard via ingestion or inhalation of gamma emitter • Lead (high electron density) is good for shielding x and gamma rays • Iodine 125 gammas (30 keV) can be easily stopped with 1/8 inch of lead
  • 14. paper plastic lead alpha particle beta particle gamma ray x-ray e- e- e- He++ photon Neutron shielding material depends on the energy of the neutrons
  • 15. Bremsstrahlung X-Rays • Bremsstrahlung x-ray intensity increases with increasing atomic number of absorber, and the average x-ray energy increases with increasing electron energy. (activity of the source is also a factor) x-ray e- plastic lead electrons
  • 16. Shielding for beta emitting material 90Sr plastic lead
  • 17. Low energy gamma or x-ray High energy gamma or x-ray Shielding for gamma emitting material
  • 18. Typical background is 0.03 mR/hr or 100 cpm GM pancake probe NaI probe Range selector Battery check
  • 19. Sources of Average Radiation Dose to the U.S. Population Radon, 200 55% Internal, 39 10% Terrestrial, 28 8% Cosmic, 27 8% Nuclear Medicine, 14 4% Medical x-rays, 39 11% Consumer Products, 10 3% Other, 3 0.8% Source: BEIR V Report, 1990 Background Radiation 360 millirem per year
  • 20. Annual Occupational Dose Limits Whole Body 5,000 mrem/year Lens of the eye 15,000 mrem/year Extremities, skin, and individual tissues 50,000 mrem per year Minors 500 mrem per year (10%) Embryo/fetus* 500 mrem per 9 months General Public 100 mrem per year * Declared Pregnant Woman
  • 21. Biological Effects • Many groups exposed to ionizing radiation at high levels resulted in adverse effects. • Somatic effects – Prompt - skin burns and cataracts – Delayed - cancer • Genetic effects • Teratogenetic effects
  • 22. X-Ray Burns 5,000+ rad 500+ rad P-32 - 6.5 rad/hr/uCi S-35 - 2.5 rad/hr/uCi
  • 23. Cancer • Radiation can damage cells through two methods; – Production of free radicals and – Direct damage to the DNA. • Risk factor for radiation dose: – 4% increase in risk of dying of cancer for every 100 rem of dose. – Normal cancer risk is 20%.
  • 24. 0 10 20 30 40 50 60 70 Committed Lifetime Dose (rem) 0.00 0.01 0.02 0.03 Risk of death from cancer Dose Response Relationship Predictable Effects Risk Is not Predictable below 20 rem Effect is Detrimental risk level is uncertain Occupational dose – above background
  • 25. ALARA • ALARA - As Low As Reasonably Achievable • Time • Distance (inverse square law) • Shielding • Contamination Control
  • 26. Inverse Square Law 5 mrem/hr @ 10 cm 50,000 mrem/hr @ 0.1 cm 45 mrem/hr @ 3.3 cm D2 . D1 x1 x2 2 D - Dose x - distance
  • 27. Radioactive Sealed Sources • Sealed sources used as a source of radiation – Alpha particles – Beta particles – Gamma ray – Bremsstrahlung – Neutron sources • Permanently enclosed in either a capsule or another suitable container designed to prevent leakage or escape of the radioactive material • Inventory and Use records are required
  • 28. • Tested for surface contamination and leakage – Sources may leak radioactive material – Tested usually once every 6 months for beta & gamma emitters that are > 100 uCi – Tested every 3 months for alpha emitters > 10 uCi – Allowable limit is less than 0.005 uCi • A leaking source shall immediately be removed from use – Action to be taken to prevent contamination – Source to be repaired or disposed of • RPP has a shielded storage facility for sources that are not in use. Radioactive Sealed Sources
  • 29. Security and Transportation • All radiation sources must be kept locked up when not in use. • Experiments left unattended should be labeled “Experiment in Progress.” • An up-to-date use log of all sources must be kept at the storage location. • All radiation laboratories will be locked when unattended for extended periods. • When you are the means for security, you must challenge unknown persons entering the lab. • Sources can only be used in a registered radiation laboratory. • Call RPP for all transfers of sources to other authorizations.
  • 30. General Radiation Safety • No food or beverages in the lab • Keep a survey meter conveniently close by • ALARA - time, distance, and shielding • Label radioactive materials and equipment • Never remove sources from the Jr Physics Lab
  • 31. Experimental Setups Moessbauer Spectroscopy • 10 mCi 57Co source (122 keV gamma) • Exposure Rates – 9000 mR/hr at 1 cm – ~1 mR/hr at 3 feet • With shielding – Background levels E/M experiment • 10 mCi 90Sr/Y (b) and 110 uCi 133Ba (g) source • Exposure Rates • 90Sr/Y - skin • 9000 mrad/hr to skin • 133Ba – whole body • 2.6 mR/hr at 10 cm
  • 32. Experimental Setups cont… Alpha Decay • Natural U, Th, and Ra in rocks • Exposure Rates – 0.1 mR/hr at 1 foot – Contact 3mR/hr - gamma – Contact 35 mrad/hr - beta Compton Scattering • 500 uCi 137Cs source • Beta and gamma emitter • Exposure Rates • 1.5 mR/hr at opening • 0.15 mR/hr on contact with lead • Background levels in area
  • 33. Experimental Setups cont… Rutherford Scattering • 165 uCi 241Am source • Alpha and gamma emitter • Alpha 5.5 MeV • Gamma ~ 60 keV • Many smoke detectors have 1 uCi of 241Am
  • 34. When do you contact RPP? • Missing radioactive material • Suspected leaking source • Suspected accidental exposure • Questions or concerns • Call x2-3477 between 9am-5pm or x100 any time