Transcript Naturally Occurring Radionuclides

‫جمهورية العراق‪ /‬وزارة العلوم والتكنولوجيا‬
‫مديرية السالمة االشعاعية والنووية‬
‫(‪(NORM in Oil Industry‬‬
‫بغداد‪ – 30‬نيسان ‪2012 -‬‬
‫اعداد‬
‫د‪.‬يوسف محسن زاير ‪/‬مدير مديرية السالمة‬
‫االشعاعية والنووية‬
‫خبير‪/‬باحث علمي اقدم‬
NORM and TENORM
NORM: All Naturally Occurring Radioactive
Materials 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 Technologically Enhanced Naturally Occurring
Radioactive Materials (TENORM ) – and (or)
enhanced potential for exposure to naturally
occurring radioactive materials in products, byproducts, residues and wastes.
U-238
4,47 x 109
y
Th-234
24.1 d
U-234
248,000 y
Uranium series
Pa-234m
1.17 min
Emission of
beta particle
Th-230
75,400 y
Isotope
half-life
Ra-226
1620 y
Emission of
alpha
particle
Rn-222
3.82 d
Po-218
3.11 min
Bi-210
5.01 d
Bi-214
19.9 min.
Pb-214
26.8 min.
Po-210
138 d
Po-214
164 μs
Pb-210
22.3 y
Pb-206
stable
Thorium series
Th-232
14.1 x 109 y
Th-228
1.91 y
Emission of
Beta particle
Ac-228
6.13 h
Ra-228
5.75 y
Isotope
half-life
Ra-224
3.62 d
Emission of
alpha-particle
Rn-220
55.6 s
Po-216
145 ms
Po-212
0.299 s
Bi-212
60.55 min
Pb-212
10.64 h
Pb-208
Stable
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), carbon14 (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
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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 production including 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 (lead210) 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
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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 carbonate
scales on the inner walls of production equipment (e.g.
pipes, valves, pumps).
Hazards of NORM
• Because NORM scale 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 offline 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 total radium
concentrations typically range from
undetectable levels to several thousand Pico
curies per liter or gram.
Anomalously high concentrations up to
15.170 MBq/Kg in scale
 25.900 MBq/Kg in sludge ,
203 kBq/Kg in water,
in more recent studies, Available data indicate
that total radium concentrations range from
undetectable levels to 103.600 MBq/Kg in most
produced water.
Scale
The source term concentrations used in this
assessment were based on the scale and sludge
composite concentrations used in a risk assessment
conducted by the EPA and the state of Louisiana,
Total radium concentrations in scale typically range
from undetectable levels to concentrations as high
as 151.700 MBq/Kg have been reported.
The median concentrations for total radium in scale
was 17.760 kBq/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
Sludge deposits 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
25.900 MBq/Kg had been documented .
The median concentrations for total radium in
sludge was 2.775 kBq/Kg , (2.072 kBq/Kg for Ra226 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
Bq/g dry scale
Activity concentrations in five samples of scales
900
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200
100
0
Pb-210
Ra-226
Ra-228
Th-228
Scale 1
Scale 2
Scale 3
Scale 4
Scale 5
Types of NORM residues
Norm Concentrations in Sludge
Activity concentrations in four samples of sludges
Bq/g dry sludge
250
200
Pb-210
Ra-226
Ra-228
Th-228
150
100
50
0
Sludge 1
Sludge 2
Sludge 3
Sludge 4
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 5,300 μR/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 safety assessments 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).- Terrestrial pathways:
• Ingestion of contaminated foodstuffs.
• External irradiation.
-Aquatic pathways:
• Ingestion of contaminated water.
• Ingestion of foods produced using irrigation, fish
and other aquatic biota.
NORM Contaminated Scrap
Contaminated Items
Scrap Items from a NORM Facility
NORM Scales (Pipes)
Scale and Sludge
Disposal of Production Water on
Purpose to Evaporate
Disposal of scale and sludge
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 gamma radiation 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 radiation exposures.
• 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 safe manner in accordance with
the regulatory requirements.
Thank you for your Attention