Radiochemistry

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Radiochemistry

• Concepts and Applications in Environmental
  Chemistry

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Isotopes

• Too heavy, too light, rarely just right.

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Table of Isotopes

• 1998 Version, 3000 isotopes

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Properties of ?, ?, ? and ?

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Properties of ?, ?, ? and ?

• ALPHA BETA X-, GAMMA
• Symbol ?, 42He 2 ?, 0-1?, 0-1e ? and ?
• Charge 2 -1 0
• Mass (kg) 6.642x10-27 9.116x10-31 0
• Velocity 0.05c up to 0.995c c
• (c2.998x108m/s)
• Relative
• Ionization 1x104 1x102 1
• Potential
• Relative
• Penetrating 1 1x102 1x104
• Potential

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Penetration Potential
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Ionization of Gas
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Ionization of Liquids

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? Scintillation Detection

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Solid-State Semiconductor Detectors

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HPGe Detector StructureCANBERRA Analytical
Nuclear Instruments
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Ionization of Solids
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? Spectroscopy with HPGe

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Ultra-Low Background Considerations
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Cosmogenic - from the cosmos
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Auroras
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Naturally Occurring Radioactive Materials (NORM)

• Cosmogenic
• 3H 7,10Be 14C 18F 22,24Na 26Al
  31,32Si 32,33P 35,38S 36,38,39Cl 37,39Ar
  53Mn 59Ni 80Kr
• Primordial
• 40K 50V 87Rb 113Cd 115In 123Te 138La
  144Nd 147Sm 148Sm 152Gd 174Hf 176Lu
  187Re 190,192Pt 209Bi
• 232Thdaughters 235Udaughters
  238Udaughters
• 237Npdaughters

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Localized Hot Spots

• Location Annual Dose(mSv/y)
• United Arab Emirates 14
• Radon Springs, France 16
• Kerala Region of India 30
• Guangdong Province, China 33
• Morro De Faro, Brazil 70 - 140
• Guarapari, Brazil 175
• Ramasari, Iran 480
• USNRC Occupational Dose Limit 50
• USNRC Limit for Members of Public 20

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Oklo Quarry, Gabon
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Fossil Fission Reactor

• Oklo Quarry, Gabon
• In 1972 ore deposits were found to contain
  significantly different isotopic compositions of
  certain elements than from the mean found in
  nature.
• 142Nd normally 27 in nature, at Oklo it was lt6.
• 99Ru normally 28 in nature, at Oklo it was 13.
• 235U normally 0.72, at Oklo it was 0.48.
• From 87Rb/87Sr dating, Oklo deposits are 1.7E9
  years old, at that time U enrichment was 3
  235U!

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Fossil Fission Reactor

• Operated on and off at 100kW output for 1E6
  years.
• Once the natural reactors burned themselves out,
  the highly radioactive waste they generated was
  held in place deep under Oklo by the granite,
  sandstone, and clays surrounding the reactors
  areas
• Significance today with Yucca Mountain proposed
  national repository.

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Radioactive Material is Everywhere

• Cosmic Radiation
• Indoor Air Structural Materials
• Rock Soil Radiation
• Water Aquatic Food Ingestion
• Food, milk digestion
• Crop digestion
• Inhalation Skin Absorption

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Reference Man with a 70Kg. Body Mass
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Sources of Radiation Exposure -UpdateRelease of
NRCP No. 160 (03/03/09)
Exposure Category Effective Dose per Individual in the US Population (mSv) Effective Dose per Individual in the US Population (mSv) Effective Dose per Individual in the US Population (mSv)
Exposure Category (1) 2006 (2) Early 1980s Ratio (1)/(2)
Ubiquitous Background 3.11 3.00 1.04
Medical 3.00 0.53 5.67
Consumer 0.13 0.13 ---
Industrial, educational, research 0.003 0.001 ---
Occupational 0.005 0.009 ---
Total 6.25 3.67 1.70
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Energy Liberated can be Absorbed

• Absorption in body tissue may result in
  physiological injury
• Absorption is the principle by which detection is
  based.
• The degree of absorption or type of interaction
  is a primary factor in determining shielding
  requirements.

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Health Effects of Ionizing Radiation

• Direct Effect on Cells
• damage to DNA from ionization.
• If the cell is exposed to radiation, the
  probability of the radiation interacting with the
  DNA is very small since these critical components
  take up less than 0.5 of the cell volume.
• USDOE Human Genome Project

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Health Effects of Ionizing Radiation

• Indirect Effect on Cells
• decomposition of water.
• If the cell is exposed to radiation, the
  probability of interaction with cellular water is
  greater since water is 99.5 of the cell volume.

• Radiolysis of water produces the following types
  of sequences
• H2O ? ray ? HOH e- H2O e- ? HOH-
• HOH ? H OH HOH- ? H -OH
• OH OH ? H2O2 (hydrogen peroxide)
• Net Effect Free radical formation

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Risk Models
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ALARA

• The basic tenants of ALARA are the use of time,
  distance, and shielding to minimize radiation
  exposures.

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Radon Target Organ - Lungs

• Radon (Rn) and Daughter Products (RDPs) inhaled
  or ingested.
• Most of the Rn from respiration is exhaled.
• Ingested Rn out-gasses through the lungs.
• RDPs remain stuck to lung tissue. Po218 Po214
  emit alpha particles within the 1st hour.

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Alpha Particle in the Lung

• Alpha particles strike lung cells causing
  possible physical and/or chemical damage.
• 3 fates for cell
• Damaged Repaired
• Damaged, not Repaired
• Killed
• 48 hour time lapsed microscopic photograph of
  alpha tracks emitted from a radioactive particle
  of Pu-238 lodged in the lung tissue of an ape.
• www.ccnr.org/alpha_in_lung.html

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Iowa Radon Lung Cancer Study

• Found excess risk of 50 for exposures that are
  equivalent to 15-years spent at an average radon
  exposure of 4 pCi/L. Overall, the risk estimates
  obtained in the study suggest that cumulative
  Radon exposure in the residential environment is
  significantly associated with lung cancer risk.
• Field, R.W., Lynch, C.F., Brus, C.P., Woolson,
  R.F., Fisher, E.F., Platz, C.E., Robinson, R.A.,
  Steck, D.J., Neuberger, J.S. Residential Radon
  Gas Exposure and Lung Cancer The Iowa Radon
  Lung Cancer Study, American Journal of
  Epidemiology, 151(11)1091-1102, 2000.

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Radon Geology

• Source
• Rn is constantly being generated by the uranium
  in rocks, soil, water, and construction materials
  derived from rocks and soil.
• Uranium is found in small concentrations
  throughout the earths crust. On average, 1 acre
  down to a 5 ft. depth would contain 50 lbs. of
  Uranium.
• www.atral.com/U238.html

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Radon Potential ? Uranium Potential

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Actual Radon Zones

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Radon Migration

• Typical Indoor Air Rn range - 1 to 1000 pCi/L.
• Typical Soil Air Rn range - 200 to 100,000 pCi/L.
• Dissolved Rn in Groundwater range - 100 to
  3,000,000 pCi/L.

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High Variability in Radon Concentration

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Nuclear Generating Plants
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Every form of energy generation has advantages
and disadvantages.

• Coal
• Advantages
• Fuel is inexpensive
• Easy to recover (in U.S. and China)
• Disadvantages
• Requires expensive air pollution controls (e.g.
  mercury, sulfur dioxide)
• Significant contributor to acid rain and global
  warming
• Requires extensive transportation system
• Clean Coal does not yet exist

• Nuclear
• Advantages
• Fuel is inexpensive
• Energy generation is the most concentrated source
  
• Waste is more compact than any source
• Extensive scientific basis for the cycle
• Easy to transport as new fuel
• No greenhouse or acid rain effects
• Disadvantages
• Requires larger capital cost because of
  emergency, containment, radioactive waste and
  storage systems
• Requires resolution of the long-term high level
  waste storage issue in most countries
• Potential nuclear proliferation issue

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New NGP designs - ABWR
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New NGP designs - PBMR
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• Westchester County Dept. of Labs Research is a
  FRMAC partner
• Laboratory and Personnel Assets are registered in
  the event of an emergency