NORM and TENORM: Occurrence, Characterizing, Handling and Disposal

Transcription

1 NORM and TENORM: Occurrence, Characterizing, Handling and Disposal Ionizing Radiation and Hazard Potential John R. Frazier, Ph.D. Certified Health Physicist May 12, 2014

2 Radiation Radiation is a word that brings many thoughts to every person. What is the first word that comes to your mind when you hear the word radiation? There are many types of radiation that we are a part of our everyday world.

3 Ionizing Radiation Radiation that has enough energy to ionize atoms is called ionizing radiation. Types of ionizing radiation include: Alpha Particles Beta Particles Gamma Rays X Rays

4 Radiation Interactions With Matter Radiation interacts with matter by depositing some or all of its energy in the matter that it hits Charged particles (e.g., alpha particles and beta particles) ionize or excite the atoms in matter Gamma rays and x-rays interact primarily with electrons

5 Ionization Interactions Ionization is the process wherein the radiation interacts with matter and deposits some or all of its energy in atoms (or molecule) by knocking out one or more electrons from the atom or molecule. The atom is thus ionized and needs one or more electrons. If the atom is part of a molecule, this may lead to molecular dissociation ( breaking ) and recombination.

6 Radiation and Radioactivity Radiation is energy in transit, either as particles or electromagnetic waves. Radioactivity is the characteristic of some materials to emit ionizing radiation. Radioactive materials emit radiation. (Important Distinction!)

7 Properties of Radionuclides Half-Life Decay Mode (How They Decay) Type and Energy of Emitted Radiations Frequency of Emitted Radiations Where do I find this type of information?

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9 Radioactive Material of Interest Naturally Occurring Radioactive Material (NORM) Technologically Enhanced Naturally Occurring Radioactive Material (TENORM)

10 NORM Radionuclides of Interest Radium-226 (Ra-226) and Radium-228 (Ra-228) Present throughout the earth. Present in trace amounts by mass. Chemical properties similar to calcium and barium. Can be very mobile in the environment. Of interest as a source of radiation dose.

11 Properties of Radium-226 Half-life: 1,600 years Radiation Emitted: alpha particles (100%) gamma rays (3.3%) Decays to: Radon-222 subsequently to other gamma-ray emitters

12 Properties of Radium-228 Half-life: 5.75 years Radiation Emitted: beta particles (100%) (no gamma rays) Decays to: Actinium-228 (gamma-ray emitter)

13 Natural Background Radiation Cosmic Radiation Terrestrial Radiation Radionuclides Inside Our Bodies Radon and Radon Progeny

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15 Cosmic Radiation Doses

16 Terrestrial Radiation Doses

17 Man has always lived in the presence of naturally occurring radioactive material. We live in a virtual sea of natural background radiation.

18 Radiation Detection Principles Because we can t detect ionizing radiation with any of our senses, we must use special instruments to detect it. Radiation must interact with a detector. The interaction produces an electrical signal (such as an electrical pulse). The signal is displayed or recorded with a meter.

19 Gamma Ray Detector (Scintillation Type) Incident Gamma Ray Sodium-Iodide Crystal for Gamma Ray Measurements Light Photon Photomultiplier Tube - Photocathode Dynode Anode High Voltage Source and Electrical Pulse Measuring Device Optical Window

20 NORM in the Earth Uranium Decay Series Alpha Emitters (U-238, U-234, Ra-226, & others) Beta Emitters (Th-234, Bi-214, Pb-214, & others) Gamma Emitters (Th-234, Ra-226, Bi-214, & others) Thorium Decay Series Alpha Emitters (Th-232, Th-228, & others) Beta Emitters (Ra-228, Bi-212, Pb-212, & others) Gamma Emitters (Bi-212, Pb-212, Pb-210, & others) Actinium Decay Series (U-235) Other Naturally-Occurring Radionuclides K-40

21 Uranium E9 y Uranium E5 y Uranium Decay Series Protactinium-234m 1.2 m Thorium d Thorium E4 y Radium y Radon d Polonium m Polonium ms Polonium d Beta Decay Alpha Decay Lead m Bismuth m Lead y Bismuth d Lead-206 Stable

22 Thorium E10 y Thorium y Thorium Decay Series Actinium h Radium y Radium d Radon s Beta Decay Alpha Decay Polonium s Lead h Bismuth m 35.9% Thallium m Polonium us 64.1% Lead-208 Stable

23 Measures of Radioactivity Activity is the quantity or amount of radioactive material. Unit: curie is defined as 37 billion disintegrations per second picocurie (pci) is equal to 2.22 disintegrations per minute (dpm) (Each person has about 10,000 pci of radioactive material in their body.)

24 Activity Units Conversion International Unit for Activity: becquerel (Bq) = 1 dps Unit Conversion: 1 Bq = pci e.g., 100 Bq/kg = 2.70 pci/g

25 Exposure to Radioactive Materials Can Produce a Radiation Dose

26 External Radiation Dose From Radiation Sources Outside the Body Measured With External Dosimeters Calculated From External Radiation Dose Rate(s) and Exposure Duration(s) External Dose Rates Usually Vary With Time and Location Assessed with an Exposure Pathways Analysis and Dose Assessment

27 External Radiation Dose Dose external = DR x ED where H external = external radiation dose DR = external dose rate (at the location where the individual is exposed) ED = exposure duration (the total time that the individual is at the location with dose rate DR)

28 Internal Radiation Dose From radioactive materials inside the body. Radionuclides enter the body by inhalation, ingestion, injection (e.g., via a wound), or dermal absorption. Internal doses to organs or tissues vary. Internal doses are assessed by in vivo and in vitro methods or Exposure Pathways Analysis and Dose Assessment

29 Internal Dose Calculations Dose = Intake Activity x Dose Coefficient where the intake activity may be calculated from an intake rate and duration of intake or calculated from bioassay (e.g., whole body count) data and the dose coefficient is given in publications (e.g., ICRP 72) based on the radionuclide, chemical/physical form, and route of intake (inhalation or ingestion)

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31 Total Radiation Dose Total radiation dose to an organ or tissue is the sum of the external dose to the specific organ or tissue and the internal dose to the same organ or tissue. Total radiation dose is the quantity that must be determined when assessing likely causation of damage or harm (e.g., cancer) to the organ or tissue.

32 Exposure Rate Applies Only to Gamma Ray (or X-Ray) Interacting in Air Measured With a Gamma Radiation Survey Meter Represents the Amount of Ionization of Air per Mass of Air per Time Common Unit is the microroentgen per hour ( R/hr)

33 Average Annual Radiation Dose from Natural Background Radiation Sources Natural Sources Radon 211 millirem Cosmic 20 millirem Cosmogenic 10 millirem Terrestrial 30 millirem In the Body 40 millirem Total Annual Dose 311 millirem Reference: NCRP Report No. 160 (2009)

34 Average Annual Radiation Dose from Medical Sources of Radiation Medical Sources CT 147 millirem Nuclear Medicine 77 millirem Interventional Fluoroscopy 43 millirem Conventional Radiography and Fluoroscopy 33 millirem Total Annual Dose 300 millirem Reference: NCRP Report No. 160 (2009)

35 Radiation Doses Annual Occupational Dose Limit Radiation Dose from Abdomen CT Scan Average Annual U.S. Population Dose Average Annual U.S. Background Dose Average Annual Dose from Radon Radiation Dose from Head CT Scan Annual Dose Limit for General Population Effective Dose from a Chest X-ray Dose from Round-trip Flight LA to NY 5,000 millirem 1,000 millirem 620 millirem 311 millirem 228 millirem 200 millirem 100 millirem 10 millirem 2 millirem

36 Sources of Radiation Doses

37 Biological Effects of Ionizing Radiation Known to Occur at High Doses Non-Stochastic Effects: A health effect where the severity of the effect increases with dose: (and only at very high doses) Cataracts Sterility Loss of Hair (Epilation) Skin Reddening (Erythema) Acute Radiation Syndrome Death Stochastic Effects: A health effect where the risk of occurrence increases with dose: Cancer

38 Health Physics Society Benchmark The Health Physics Society issued a formal position statement in 2010 stating that: the risk of health effects from radiation doses less than 5,000 millirems per year is so small that it does not exist or cannot be detected. HPS Level Average Yearly Exposure 5,000 mrems 620 mrems

39 Operations That Can Generate TENORM Purification of Drinking Water Production of Phosphate Fertilizer Extraction of Rare Earth Elements Elemental Phosphorous Production Natural Gas Production Crude Oil Production Numerous Other Examples

40 The Amount of the Dose Matters When assessing the potential hazards or possible health effects from radiation exposure the amount of the dose must be first be determined. It is meaningless to say I was exposed to radiation. because everyone is exposed to ionizing radiation every day of our lives from natural background radiation.

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45 Source of NORM in Oil Production Activities Produced water carries the radium to the ground surface. The radium is unintentionally concentrated in scale and sludge.

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47 Composition of Scale and Sludge Scale occurs in tubing, flowlines, and coatings on pump rods. Scale is generally composed of barium sulfate (barite) with smaller amounts of calcium carbonate. Both are insoluble. Sludge occurs inside heater treaters, separators, and in tank bottoms. Sludge appears to include barite as coatings on grains of sand and other precipitates during oil production.

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49 Potential Exposure Pathways External exposure (from radiation sources outside the body) Internal exposure (from radioactive material taken into the body) Inhalation Ingestion Injection (e.g., cuts, abrasions, wounds) Dermal absorption (not a pathway for oilfield NORM)

50 Basic Concept of Radiation Doses Radiation Dose is the Energy Deposited by Ionizing Radiation in Tissue Divided by the Mass of Tissue in Which the Energy is Deposited A commonly used unit of radiation dose is the millirem.

51 Dose Assessment Each exposure pathway is represented by a mathematical formula that includes parameters for each aspect of the exposure. The values of the dose calculation parameters are determined from site-specific information (if possible) or default values (assumptions) whenever site-specific values are not available. The radiation doses from all of the exposure pathways are added to give the total radiation dose.

52 Radiation Doses From Working Around Oil Field NORM Radiation doses depend of a number of factors (e.g., amounts and locations of NORM and how long you work in a specific location). External doses are much more likely than internal doses. Radiation doses from working around oil field NORM are nearly always less than the doses from natural background radiation.

53 Basic Radiation Quantities and Units Activity: The number of atoms that decay per unit time. A commonly used unit is the picocurie (pci). Exposure Rate: A measure of the amount of ionization of air per unit time by gamma rays or X rays. A commonly used unit is the microroentgen per hour ( R/hr). Dose Equivalent: A measure of the radiation energy deposited in the human body per unit mass of tissue, taking into account the type of radiation. A commonly used unit is the millirem (mrem).

54 Radiation Quantities Exposure: A measure of ionization in air from x-ray and gamma rays. roentgen (R), or milliroentgen (mr), or microroentgen ( R) Dose: A measure of the energy absorbed in any material as a radiation interacts within it. rad or mrad, gray (Gy). [1 Gy = 100 rad] Dose equivalent: A measure of risk associated with a given radiation dose to a person. rem or mrem, sievert (Sv). [1 Sv = 100 rem]