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جمهورية العراق/ وزارة العلوم والتكنولوجيا مديرية السلامة الاشعاعية والنووية ( (NORM in Oil Industry بغداد30 – نيسان - 2012 اعداد د.يوسف محسن زاير /مدير مديرية السلامة الاشعاعية والنووية خبير/باحث علمي اقدم. NORM and TENORM.
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جمهورية العراق/ وزارة العلوم والتكنولوجيا مديرية السلامة الاشعاعية والنووية ((NORM in Oil Industry بغداد30 – نيسان - 2012 اعداد د.يوسف محسن زاير /مدير مديرية السلامة الاشعاعية والنووية خبير/باحث علمي اقدم
NORM and TENORM • NORM: All NaturallyOccurringRadioactiveMaterials where human activities have increased the potential for exposure in comparison with the normal situation. • Human activities may lead to enhanced concentrations of radionuclide – often referred to as TechnologicallyEnhancedNaturallyOccurringRadioactiveMaterials (TENORM ) – and (or) enhanced potential for exposure to naturally occurring radioactive materials in products, by-products, residues and wastes.
Uranium series U-2384,47 x 109 y U-234248,000 y Pa-234m1.17 min Emission of beta particle Th-23075,400 y Th-23424.1 d Isotopehalf-life Ra-2261620 y Emission of alpha particle Rn-2223.82 d Po-210138 d Po-2183.11 min Po-214164 μs Bi-2105.01 d Bi-214 19.9 min. Pb-206stable Pb-21022.3 y Pb-21426.8 min.
Thorium series Th-23214.1 x 109 y Th-2281.91 y Emission of Beta particle Ac-2286.13 h Isotopehalf-life Ra-2285.75 y Ra-2243.62 d Emission of alpha-particle Rn-22055.6 s Po-216145 ms Po-2120.299 s Bi-21260.55 min Pb-21210.64 h Pb-208Stable
Naturally Occurring Radionuclides There are numerous naturally occurring radionuclides. The radionuclides most commonly found in nature include the following primordial radionuclides of terrestrial origin: • the uranium series (238U and its decay products) • the thorium series (232Th and its decay products) • potassium-40 (40K)
Natural Radionuclides of Little Significance Numerous other naturally occurring radionuclides (e.g. the actinium series (235U and its decay products), carbon-14 (14C) and other cosmogenic radionuclides derived from cosmic particle and rays (e.g. 7Be)) can occur in nature however these are of little significance in terms of radiation exposures.
NORM industry candidates • Mining and processing of uranium ores • Rare earths mining/extraction • Thorium extraction & use • Niobium extraction • Oil and gas (scales, sludge, produced water, comtaninated sand/soils) • Phosphate industry (residues from mining and fertilizers production) • Zircon & zirconia • TiO2 pigment production • Metals production (Sn, Cu, Al, Fe, Mg, Zn, Pb) • Water and waste treatment residues (filters, sludge) • Energy productionincluding coal power production, geothermal energy production . • Miscellaneous industrial sources and consumer products such as, production of clay and ceramics, glazed tableware with elevated levels uranium and/or thorium, and small industrial sources such as welding rods containing elevated levels of thorium, as well as scales, sludge and contaminated filters from different types of processing,………… etc.
NORM in oil gas production • Scales or hard deposits in production tubulars and topside equipment which has been in direct contact with the production stream, • Contaminated sludge, sand, clay, heavy oil in the production system (separators, skimmer tanks.....etc.), • Enhanced levels of natural radionuclides in produced water, • contamination soils, sand, lakes/water pounds, ground water resources and sea water, • Thin films or condensates and contaminated steel (lead-210) in production, transport and storage systems in gas production (and/or in mixed oil-gas production), • NORM residues in decommissioning of production installations and restoration of NORM contaminated areas.
The main forms of appearance of NORM in oil and gas production • Radium scales ,Radium sludge • Lead deposits ,Lead films • 226Ra, 228Ra, 224Ra ,& progeny • 210Pb ,& progeny • Hard deposits containing sulphates and carbonates of Ca, Sr, Ba • wet parts of production installations • well completions • Sand, clay, paraffin, heavy metals • separators • skimmer tanks • Stable lead deposits • oil & gas treatment and transport
NORM residues • Many NORM residues are produced in very large volumes, although the activity concentration of radionuclides is relatively low. • However, there are some residues where the volumes are smaller but the levels of radioactivity are relatively high. • There is also the possibility that a NORM residue from one industry may be regarded as a raw material or a feedstock for further processing.
NORM residues, cont. • Residues may be chemically toxic and/or radioactive, • Residues can range from dry solids (varying from rocks to fine powders), • Other chemical constituents within the material may include heavy metals, inorganic elements (e.g. arsenic) and various organic compounds, • The potential for such non-radiological substances needs to be considered when planning the management of NORM residues.
NORM residues cont. • NORM residues come in many forms, including: • Scales from formation water from oil and gas production • Sludge from water filtration systems • Residues from metal processing e.g. red mud, tailings , slag, • NORM residues are usually characterised by being in large volumes with low specific levels of radioactivity e.g: • Uranium mill tailings and phosphogypsum • NORM residues can also be small volumes containing high levels of specific radioactivity e.g. • Sludge from water treatment plants; - scale from oil & gas pipelines
Example of NORM residues production : Oil and Gas Industry • Dissolved matter in formation water • Transport with produced water • Deposition on insides of pipes, valves, vessels • The water contained in oil and gas formations contains 228Ra, 226Ra and 224Ra dissolved from the reservoir rock, together with their decay progeny. • When this water is brought to the surface with the oil and gas, changes in temperature and pressure can lead to: • the precipitation of radium rich sulphate and carbonatescales on the inner walls of production equipment (e.g. pipes, valves, pumps).
Hazards of NORM • Because NORMscale generally contains so little activity, the external radiation field is generally low. However some old tubular, separators or pumps may give measurable radiation fields. • Because of the high alpha content, NORM scale is a significant internal hazard. • Requirement needs to stop NORM scale particles being inhaled or ingested. • precautions should be taken when working with NORM .
Source Term Characterization • Dissolved radium either remains in solution in the produced water or, if the conditions are right, precipitates out in scales or sludge, equipment may contain residual quantities of NORM-contaminated water, scale, or sludge that can cause exposure problems when the equipment is taken off-line for maintenance, repair, or replacement.
Numerous surveys had been conducted by industry and state agencies to characterize the occurrence and distribution of NORM. • Unfortunately, most of the data from these surveys are not readily available. • because they have been collected by private companies and the lack of access to data.
Data published from some of the earlier surveys indicate that totalradium concentrations typically range from undetectable levels to several thousand Pico curies per liter or gram. • Anomalously high concentrations up to 15.170MBq/Kg in scale • 25.900MBq/Kg in sludge , • 203kBq/Kg in water, • in more recent studies, Available data indicate that totalradium concentrations range from undetectable levels to 103.600MBq/Kg in most producedwater.
Scale The source term concentrations used in this assessment were based on the scale and sludgecomposite concentrations used in a riskassessment conducted by the EPA and the state of Louisiana, • Total radium concentrations in scale typically range from undetectable levels to concentrations as high as 151.700MBq/Kg have been reported. • The median concentrations for totalradium in scale was 17.760kBq/Kg (13.320 kBq/Kg for Ra-226 and 4.280 kBq/Kg for Ra-228). • The EPA estimates that approximately 25,000 tons of NORM-contaminated scale is generated annually by the petroleum industry. • EPA=U.S. Environmental Protection Agency
Sludge • Sludgedeposits consist of accumulations of heavy hydrocarbons, produced formation sand, and minor amounts of corrosion and clay debris that settle out of suspension in some oil field equipment. • NORM accumulates in sludge when radium co precipitates with silicates and carbonates inside piping, separators, heater/ treaters, storage tanks, and any other equipments.
NORM of sludge concentrations range from undetectable levels to high concentration as 25.900MBq/Kg had been documented . • The median concentrations for total radium in sludge was 2.775 kBq/Kg , (2.072 kBq/Kg for Ra-226 and 0.703 kBq/Kg for Ra-228). • The EPA estimates that approximately 225,000 t of NORM contaminated sludge is generated annual.
Norm Concentrations in Scales Types of NORM residues
Norm Concentrations in Sludge Types of NORM residues
Natural gas production and processing • equipment may be contaminated with a thin film of Pb-210 plated onto interior surfaces. Lead-210 sometimes is produced along with natural gas partitioned mainly between the propane and ethane fractions. • median exposure levels for gas processing equipment range from 2 to 76 μR/h above background, • ( background level = 7 μR/h). • Maximum exposure levels had been measured as 5,300μR/h in surveys of scale or sludge inside the equipment.
For Occupational Health Purposes • Working with NORM materials can result in exposure to gamma radiation and the inhalation of long lived alpha emitting radionuclides. • The radionuclide composition of the NORM is quantified as this assists in the compilation of the occupational safetyassessments and the interpretation of the dust sampling results. • The bioassay of workers (e.g. urine sampling for uranium).
Exposure Pathways to Humans - Atmospheric pathways: • Inhalation of radon and its daughters. - Inhalation of radioactive particulates (dust).- - Terrestrialpathways: • Ingestion of contaminated foodstuffs. • External irradiation. -Aquatic pathways: • Ingestion of contaminated water. • Ingestion of foods produced using irrigation, fish and other aquatic biota.
Summary-1 • Many types of naturally occurring radionuclide are found throughout the environment. • The most important in terms of their dose contribution are the primordial radionuclides of the uranium and thorium decay chains. • The decay chains contain a complex mixture of radionuclides with widely varying physical and chemical properties. • Accumulations of materials can result in significant gammaradiation and dust concentrations in the workplace,
Summary - 2 • Non-equilibrium radionuclide mixtures can occur, • The mixtures need to be properly characterized, • Both workplace and personal monitoring may be required, • Surface contamination monitoring will be used to assess ,material and dust control systems. • In most types of samples the most important NORM radionuclides can be analyzed utilizing XRF and HpGe equipment and methods. • Sites contaminated by historical NORM residues are a common phenomena worldwide.
Summary-3 • Contaminated sites and materials may be used by the public resulting in radiationexposures. • Monitoring is required throughout the life of the facility. • The monitoring of NORM facilities is complicated by the presence of natural background radiation. • Monitoring and surveillance are essential to provide assurance that the NORM facility is operating in a safemanner in accordance with the regulatory requirements.
