Radiation Safety for Byproduct 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: ORAU NCRP

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 Category Internal, inhalation (radon and thoron) External, space Internal, ingestion External, terrestrial

Natural background E US

(mrem) 228 33 29 21 311

Medical

• • • • Computed Tomography (CT) – 24% Nuclear Medicine – 12% Interventional Fluoroscopy- 7% Conventional radiography – 5% • Total – 48%

Medical

Exposure Category CT Nuclear medicine Interventional fluoroscopy Conventional radiography and fluoroscopy

Medical E US

(mrem) 147 77 43 33 300

Other

• Consumer activities and products– 2% • Occupational exposure- < 0.1% • Industrial exposure- <0.1% • Total – about 2%

Consumer and Industrial

Exposure Category

Consumer activities and products Industrial, security, medical, educational and research E US

(mrem) 13 0.3

Average Person

Exposure Category

Natural background Medical Consumer activities and products Industrial, security, medical, educational and research Occupational

Total

E US

(mrem) 311 300 13 0.3

0.5

625

Annual Limits

Type of Exposure

Radiation worker – whole body Declared pregnant worker Minors Members of the public

Does not include background radiation or medical exposures Limit (mrem) 5000 500 100 100

Why do I need to be aware ?

Nuclear medicine patients Large hospital in town – 25000 patients per year – diagnostic About 300 per year therapuetic Scrap metal dealers Customs & Border Protection TEMA/ FD / Highway Patrol

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

Fiesta Ware • 1936 – 1943 – Fiesta Red Natural Uranium • 1943 – 1959 No production (WWII) • 1959 – 1969 - Fiesta Red Depleted Uranium • 1969 – 1973 Fiesta Red and Ironstone Depleted Uranium • • • • 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

Vaseline Glass • 1830’s started production • Natural Uranium • After 1959 • Depleted Uranium • Still being made but only for decoration not for drinking or eating • 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 !!

K-40 Half-life: 1.28 x 10 9 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!

Brazil Nuts • A mix of : • Ra-226 (1600 year half life) • Ra-228 (5.75 year half life) • 1.8 pCi/g Ra-226 • 2 pCi/g Ra-228 • Most of the radium ingested is not retained by the body

Kaolin Clay • White clay • Mined in GA and AL • Elevated levels of U and Th decay series • Radium • 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

Kitty Litter • Clay • Bentonite • Elevated levels of U and Th decay series • K-40 • 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

• Phosphorus • K-40 • N- P-K Fertilizer • 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

Magnesium- Thorium Alloy • Mag-Thor • Mg-Th-Zr • Mg-Th-Zn-Zr • Mg-Ag-Th-(rare earth) - Zr • 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

Thoriated Welding rods • • • Tungsten Inert Gas (TIG) welding Aircraft, petro chemical industries High quality welding • 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

Thorium lantern mantles • • 1884 – first production Thorium causes and incandescent glow • when heated Domestic production stopped • (Coleman) in 1990 International still ongoing • 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

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 • 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

Smoke detectors • • • • 1940 – first production 1951 introduced in US Am-241 alpha emitter • 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

Static eliminators • • • • Po-210 138 day half life alpha emitter Litvinenko – London - 2006 • 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

Luminescent paint • • • Ra-226 – old H-3 Pm-147 • 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

Gun sights • H-3 • 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 !

Exit signs • • • H-3 20 Ci (CURIES !) 10-20 year working life • 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

• 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