radiation safety for byproduct material users andy miller, ms, chp
TRANSCRIPT
Radiation SafetyRadiation Safetyfor for
Byproduct Material UsersByproduct Material Users
Andy Miller, MS, CHP
Disclaimer
My opinions - Not those of my employer of the HPS
Source for much of the material (especially photographs) is from:
ORAUNCRP
Radiation In Our Lives
Overview of Ionizing Radiation
You can not see it, smell it, or feel it We depend on training and equipment to protect ourselves.
Radiation is relatively simple to measure Unlike biological agents, we can quickly and conclusively
assess the situation and respond appropriately.
The health effects of radiation have been studied
for over 70 yrs and are well understood for high doses. Dose limits are well below the doses where health
effects are directly observed.
Sources of Radiation Exposure
Natural Background
• Space – 5%• Internal – 5%• Terrestrial – 3%• Radon and Thoron – 37%
• Total – 50%
Natural Background
Exposure CategoryEUS
(mrem)Internal, inhalation (radon and thoron) 228External, space 33Internal, ingestion 29External, terrestrial 21Natural background 311
Medical
• Computed Tomography (CT) – 24%• Nuclear Medicine – 12%• Interventional Fluoroscopy- 7%• Conventional radiography – 5%
• Total – 48%
Medical
Exposure CategoryEUS
(mrem)CT 147Nuclear medicine 77Interventional fluoroscopy 43Conventional radiographyand fluoroscopy 33
Medical 300
Other
• Consumer activities and products– 2%
• Occupational exposure- < 0.1%
• Industrial exposure- <0.1%
• Total – about 2%
Consumer and Industrial
Exposure CategoryEUS
(mrem)Consumer activities and products 13Industrial, security, medical,educational and research 0.3
Average Person
Exposure CategoryEUS
(mrem)Natural background 311Medical 300Consumer activities and products 13Industrial, security, medical,educational and research 0.3
Occupational 0.5Total 625
Annual Limits
Type of Exposure Limit(mrem)
Radiation worker – whole body 5000Declared pregnant worker 500Minors 100Members of the public 100
Does not include background radiation or medical exposures
Nuclear medicine patientsLarge hospital in town – 25000
patients per year – diagnosticAbout 300 per year therapuetic
Scrap metal dealers
Customs & Border Protection
TEMA/ FD / Highway Patrol
Why do I need to be aware ?
Granite Counter Tops
• New York Times article “What’s Lurking in Your Countertop?”• Some slabs measure approximately 1.5 times background (about 20 μR/h)• Radium which decays to Radon-222• Levels are estimated to be about 0.6 pCi/L compared to 4 pCi/L for EPA guidelines
• Very easy to detect with a Geiger Counter• Homer Laughlin Company of WV• 0.5 to 15 mR/hr• 14% U by weight of glaze
Fiesta Ware
• 1936 – 1943 – Fiesta Red Natural Uranium
• 1943 – 1959No production (WWII)
• 1959 – 1969 - Fiesta RedDepleted Uranium
• 1969 – 1973Fiesta Red and IronstoneDepleted Uranium
• Larger pieces can see with a Geiger Counter
• Fenton Glass of WV
• 27 mR/hr contact dose rate
• 2% U by weight of glass
• Fluorescence seen very well under UV light – green glow !!
Vaseline Glass
•1830’s started production•Natural Uranium
•After 1959•Depleted Uranium
•Still being made but only for decoration not for drinking or eating
K-40 Half-life: 1.28 x 109 years
Beta decay (89.3%). The beta maximum energy is 1.31 MeV
Electron Capture (10.7%).
Gamma Rays: 1461 keV (10.7%)
Daily intake of potassium element: 3.3 grams
Amount of potassium element in body: 140 grams (1.5 pCi/g or 55 Bq/kg of body weight)
Typical K-40 activity in body: 0.1 uCi; This means that there are over 200,000 atoms of K-40 that decay in the body each minute!
•1.8 pCi/g Ra-226
•2 pCi/g Ra-228
•Most of the radium ingested is not retained by the body
Brazil Nuts
•A mix of :•Ra-226 (1600 year half life)•Ra-228 (5.75 year half life)
• Domestic production now with a different chemical (but the same trade name)
•International production still uses Kaolin
•0.27 to 0.5 pCi/g of medicine
•1000 pounds per year to exceed limits
Kaolin Clay
•White clay•Mined in GA and AL•Elevated levels of U and Th decay series•Radium
• Can trip detectors due to large volumes (tractor trailer loads)
•4 pCi/g for Uranium series
•3 pCi/g for the Thorium series
•8 pCi/g for K-40
•4 billion pounds per year purchased
•50000 pounds U – 120000 pounds of Th
Kitty Litter
•Clay•Bentonite•Elevated levels of U and Th decay series•K-40
• Phosphate mining can be associated with uranium (FL)
• Can trip detectors due to large volumes (tractor trailer loads)
• U-238 22-140 pCi/g
• Th-230 5 – 430 pCi/g
• Ra-226 1 – 24 pCi/g
• Th-232 0.14 to 4.6 pCi/g
Fertilizer
•Phosphorus•K-40•N- P-K
• High strength, creep resistance at high T, light weight
• Aircraft engines, helicopter parts, rocket motors
• Parts are about 1.7% Th
• Aircraft maintenance workers – up to 50 mrem/yr
•Grinding cutting issues as well as dose rate
Magnesium- Thorium Alloy
• Mag-Thor•Mg-Th-Zr•Mg-Th-Zn-Zr•Mg-Ag-Th-(rare earth) - Zr
• Typically 1-2% thorium can be up to 4%
• Rods are color coded for throia content
• Throium increases the current carrying capacity of the electrode
• Inhalation hazard
• Grinding the tip
• Electrode consumption during welding
• Some estimates as high as 800 mrem per year with no ventilation
Thoriated Welding rods
• Tungsten Inert Gas (TIG) welding• Aircraft, petro chemical industries• High quality welding
• Burning the mantle releases airborne activity from decay products of Thorium
• Approximately 25 million mantles sold in 2000 contained Th
• Playing with ash – 2 mrem estimate
• High estimate of 200 mrem for living indoors with your only source of light as mantles (4 per year)
• Geiger counter sees this well
Thorium lantern mantles
• 1884 – first production• Thorium causes and incandescent glow when heated• Domestic production stopped (Coleman) in 1990• International still ongoing
• Radioactive materials added to slightly ionize the gas in the tube to allow for better and faster starting
• Typically pCi quantities
• Consumer product boxes will be labeled with isotope and amount
• Millions of bulbs sold each year
• Doses are much less than 1 mrem
Electron tubes and light bulbs
• Electron tubes• Co-60, Ni-63, Kr-85• Pm-147, Th-232
• Light bulbs• H-3, Kr-85, Pm-147, Th-232
• 1 to 30 uCi – smaller for homes – larger for commercial
• Some older detectors can also contain Ra-226
• Dose estimate is less than 1 mrem per year
• Disposal
• Return to manufacturer
• Landfill
• Multiple units should be shipped as radioactive waste
Smoke detectors
• 1940 – first production• 1951 introduced in US• Am-241• alpha emitter
• Ionizes the air immediately in front of the device
• Ions produced in the air are attracted to the object that has the static charge (brush)
• Typical amounts 200 to 500 uCi
• One year replacement recommended
• Small doses but heightened sensitivity due to event
• Mass balances, paint shops
Static eliminators
• Po-210• 138 day half life• alpha emitter• Litvinenko – London - 2006
• Beta particles interact with a phosphor to cause the “glow”
• Radium dial painters –
• Radium production stopped in 1978 domestically
• Military equipment (aircraft ,tanks – in museums)
• Easy to detect the Ra-226
• H-3 and Pm-147 more common and much less hazardous
Luminescent paint
• Ra-226 – old• H-3• Pm-147
• Beta particles interact with a phosphor to cause the “glow”
• About 12 mCi
• Very low energy beta emitter – GM will not work
• Easy to lose
• Exempt distribution
• Would not worry about the radiation as the biggest hazard !
Gun sights
• H-3
• Beta particles interact with a phosphor to cause the “glow”
• Anyone can buy these without a license
• Some responsibilities for:
• Inventory
• Reporting loss or damage
• Transfer to new owner
• Return to manufacturer
Exit signs
• H-3• 20 Ci (CURIES !)• 10-20 year working life
• Radioactive materials
• No eating
• No drinking
• No smoking
Dentures
1940-1970’s
Uranium added for fluorescence
Dose to the gums ??
130 rem per year estimated