Week 12 Ionizing and Non-Ionizing Radiation

Week 12 Ionizing and Non-Ionizing Radiation - Ionizing and...

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Unformatted text preview: Ionizing and NonIonizing Radiation Ionizing and Non-Ionizing Radiation Ionizing Radiation Non-Ionizing Radiation Radioactivity Defined The process by which an unstable nucleus tries to become more stable by emitting energy from the nucleus Brief Chemistry Refresher An – – – – – atom is made up of protons, neutrons, and electrons Proton __________ have a positive charge s Electron have a negative charge __________ s Jimmy ______________ have a neutral charge Neutrons Proton Neutronsare located in the _______ and __________ s nucleus – What element the atom is depends on Proton the number of ___________________ s How did we do? What is an Isotope? Same number of protons, different number of neutrons Example of nuclear notation hyperphysics.phy-astr.gsu.edu Examples of Isotopes Carbon Examples of isotopes Isotopes of hydrogen So what does it all mean? Some isotopes are unstable If unstable, the nucleus will give off bursts of energy (radiation) in an attempt to become stable. These bursts of energy or disintegrations may be in the form of – alpha particles (two protons and two neutrons positively charged), – beta particles (a negatively-charged electron) – x-rays, or gamma rays (types of high energy electromagnetic waves). Ionizing vs Non-Ionizing Radiation Ionizing radiation: Has enough energy to knock an electron out of its orbit, creating an ion (hence the word “ionizing”). Non-ionizing radiation : Do not have enough power to knock an electron out of orbit. Consists of visible light, radio waves, and infrared light. Reference: Alaska PADS – Ionizing vs Non-Ionizing Radiation Ionizing Radiation Applications Where might you encounter ionizing radiation? – IH Equipment Niton XRF Chemical detectors (gas chromatography) – Industrial equipment Fluorescent dials, etc Soil density gauges Aircraft NDI – Medical applications – Others? Radiation Safety Programs Ionizing radiation regulated by OSHA, NRC, and FDA (medical and dental xrays) – Worker safety: 29 CFR 1910.1096, Ionizing Radiation – Licensing, control, etc 10 CFR Workplace must have a Radiation Safety Officer – 40-hour course Ionizing Radiation There are three main kinds of ionizing radiation: – – – Alpha particles Beta particles Gamma and x-rays Three Types of Ionizing Radiation Alpha particles – Large in size – Include two protons and two neutrons Net positive charge of +2e – Travel at slow speed Beta particles – Are essentially electrons Net charge of -1e – Very small size – High speed Three Types of Ionizing Radiation Gamma – – – – and x-rays No mass No charge Travels at the speed of light Called a “photon” Health Effects Acute: Erythema and dermatitis. Large whole-body exposures cause nausea, vomiting, diarrhea, weakness, and death. Chronic: Skin cancer and bone marrow suppression. Genetic effects may lead to congenital defects in the employee's offspring. Evaluation of Ionizing Radiation: Units Curie (Ci): Quantity measurement of radioactive material Roentgen: Unit for measuring gamma or xrays in air Rad (radiation absorbed dose): Unit for measuring absorbed energy from radiation Rem (roentgen equivalent man): Unit for measuring biological damage from radiation – Exposure limits Exposure Limits 1910.1096 Whole body (Head and trunk; active blood-forming organs; lens of eyes; or gonads ): – 1.25 rem/calendar quarter Shallow dose (Hands and forearms; feet and ankles): – 18 3/4 per calendar quarter Pregnant workers: 0.5 rem/term Evaluation of Ionizing Radiation: Instrumentation Geiger-Mueller or Geiger counter – Good for detecting the presence and intensity of radiation – Low cost, easy to use – Mostly useful for alpha and beta radiation but also detects gamma Evaluation of Ionizing Radiation: Instrumentation Ion chamber – Used for gamma, x-ray, and some beta radiation – Capable of reporting as a dose mRem/hr Evaluation of Ionizing Radiation: Instrumentation Personal Dosimeter – Often badges that are sent off to a third party for analysis – Mostly gamma/x-ray, some beta – Worn on the outside of protective equipment Ionizing Radiation Controls Three main types of controls with radiation: – – – Time Distance Shielding Radiation Controls Time – Less time around a radiation source means less dose Distance – Inverse square law (double the distance, half the dose) Shielding – Depends on type of radiation Shielding Alpha, beta, and gamma radiation Radiation Controls Knowing what we now know about radiation, how would you control: – Alpha, beta, gamma, or x-rays using Engineering Administrative PPE Radiation Isotopes and Half Life Radiation naturally decays at a specific rate Half life is the time it takes for a material to lose 50% of its activity Sometimes it’s very short, sometimes very long – Radium-226: very long, 1602 years – Radon-222: very short, 3.8 days Radiation Isotopes and Half Life Calculating half-life A = Ai(0.5)t/T where: A = activity at time t Ai = initial activity t = time T = half-life Ionizing and Non-Ionizing Radiation Ionizing Radiation Non-Ionizing Radiation Non-Ionizing Radiation Four types we will cover here – – – – Ultraviolet (UV) Lasers Infrared (IR) Radiofrequency (RF) Types we will not cover – EMF (electromagnetic) from computers, etc Research hasn’t shown significant health effects – Microwaves Today’s microwaves pretty safe Microwave emitters, usually pretty low energy Radiation Spectrum Non-Ionizing Radiation Is a form of energy In the form of photons Travels at the speed of light Energy is related to wavelength Frequency and Wavelength f = c/λ f = frequency c = speed of light (3 x 1010 cm/sec) λ = wavelength (cm) Ultraviolet Radiation (UV) Sunlight Welding Plasma torches Tanning beds Mercury vapor lamps UV Radiation Effects: – Mostly eyes and skin – Skin cancer (UV-A) – Cataracts (UV-B and C) UV-A – Suntan UV-B – Photokeratitis (sandy eye) UV-C – Bactericidal and germicidal properties – Some welding arcs Lasers If your worksite uses lasers, you may need an LSO (laser safety officer) 5 classes (I-IV) Class I lasers – < 1 mW – Considered entirely safe even if used improperly. – Do not require any warning labeling. – CD players Lasers Class II lasers – Up to 1 mW power – Hazardous only when someone stares directly into the laser beam even though the beam hurts the eyes. – Require warnings to avoid staring directly into the beam. (Darwin?) Class IIIA lasers – 1-5 mW – Hazardous only when the laser beam is collected and focused by optical instruments Can cause eye damage before blinking Class IIIB lasers Lasers – 5-500 mW (that’s a LOT) – Can easily cause permanent eye damage from exposures of 1/100th of a second or less – Even hazardous off of reflective surfaces – Any knucklehead can order these on the internet!! – Eyewear required – Possible fire hazard Lasers Class – – – IV lasers >500 mW Need I say more? Warning signs are critical Infrared Radiation Caused from infrared heaters, blast furnaces, some welding May cause skin burns, cataracts, retinal damage Protective eyewear – Tinted welding hoods, etc – 29 CFR 1910.133 Radio Frequency Radiation Sources – – Antennas/transmitters Be careful with people working on roofs or other places where antennas may be Health effects – Spot heating – Cataracts Radiofrequency Radiation Radio transmission regulated by the FCC and OSHA Not all antennas are transmitters – Radio broadcast and amateur antennas – RF heaters – Note: the big thing on the Elvey building is a receiver, NOT a transmitter RF Radiation What to remember – Transmitting antennas should be shut down before maintenance is performed – Potential exposure can be calculated based on known transmission of antennas – Sources of RF radiation need to be marked and secured in accordance with hazard potential Radiofrequency Radiation Signage ( ) Ionizing and Non-Ionizing Radiation Ionizing Radiation Non-Ionizing Radiation ...
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