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IAEA International Atomic Energy Agency

An Overview of IAEA Industry Specific Safety

Reports on NORM

P.P. Haridasan

Radiation Safety and Monitoring Section

Division of Radiation Transport and Waste Safety

International Working Forum on Regulatory Supervision of Legacy Sites (RSLS)

Technical Meeting - 22 - 24 October 2013

IAEA

What is NORM?

“Naturally occurring radioactive material”

• It is the radionuclides that are naturally occurring, not necessarily the material (e.g. process residues)

• All materials contain certain amount of natural radionuclides

• Does that mean - Everything in the environment is NORM ?

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Definitions: IAEA Safety Glossary (version 2.0):

Material designated in national law or by a regulatory body as being subject to regulatory control because of its radioactivity

Radioactive material (as defined above)

containing no significant amounts of radionuclides other than naturally occurring radionuclides

Radioactive material

NORM


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Natural radionuclides

• U-238 and Th-232 series - prominent

• Mixture of radionuclides

• K-40

• Long-lived to short-lived radionuclides

• Gaseous forms – Rn-222 (radon)

Rn-220 (thoron)

• Alpha emitters, beta-gamma emitters

• Very high energies – Po-212 8.78 MeV alpha

• Gamma – 2.6 MeV Tl-208 IAEA TM RSLS, 24 October 2013 4

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Hazards

• External – mainly gamma exposures

• Internal – inhalation of airborne dust

– inhalation of radon/thoron and

short-lived progeny nuclides


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NORM Safety Issues

• Exposure of the workers.

• Exposure of the public.

• Protection of the environment.

• Physical security of the product.

• Transport of radioactive material.

• Ensuring the long term stability of the waste

disposal options.

• Limiting effluent discharges.

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Radionuclide behaviour during mining and mineral

processing

Mining and processing of minerals: Radionuclides can become mobilized

Disruption of equilibrium conditions that existed in the ore

Possibility of much higher activity concentrations in certain process

materials, sometimes by orders of magnitude

Main processes : Mining of ore

Physical mineral separation processes

Wet chemical extraction processes

Thermal processes for extraction, processing and

combustion of minerals


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1. Mining and comminution of ore Open pit mining

Vertical shaft

Inclined shaft

Underground drilling

Underground rockhandling

Dredge mining

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1. Mining and comminution of ore

Ore - usually in equilibrium (approximately)

Radionuclide mobilization & disruption of equilibrium - limited

Gamma exposure depends on geometry

Radon exhalation and airborne dust generation depend on:

Geology/mineralogy, e.g. igneous - sedimentary,

rock - mineral sand

Mining method, e.g. underground , surface, wet , dry

Ore comminution method, e.g. dry vs wet, crushing vs

grinding

Dust activity concentration may be different from that of ore

Wet mining and comminution may cause dissolution and

subsequent precipitation of radionuclides on equipment

surfaces


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2. Physical mineral separation processes

Phosphate rock beneficiation

plant

Gravity separation of mineral sand

Flotation

Heavy mineral concentrate

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2. Physical mineral separation processes

Includes gravity concentration, magnetic separation, electrostatic

separation, flotation in a chemically inactive environment

Limited opportunity for radionuclide mobilization & disruption of equilibrium

Gamma exposure depends principally on geometry and can be calculated

Airborne dust exposure likely to be dominant in dry separation

Activity concentration of dust may be significantly different from that of ore,

due to differing mechanical properties of ore components

e.g. preferential concentration of Th-rich monazite in dust

Wet physical processes can cause precipitation of radionuclides on

equipment surfaces, sometimes at high concentrations

e.g. precipitation from produced water in oil & gas extraction


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2. Physical mineral separation

processes

Radium-rich pipe scale in the oil and gas industry


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3. Wet chemical extraction processes

Chemical leaching is applied in situ or to crushed/milled ore

Strong acid or alkali leaching results in significant extraction of

radionuclides

Dissolved radionuclides can precipitate out in scales, sludges,

filters, rubber linings and resins, often at high

concentrations

Most prevalent during solvent extraction, ion exchange,

metal recovery by electrochemical processing

(electrowinning), etc.

Implications for exposure to gamma radiation and dust

Chemistry of the radio-elements involved differs widely

Radionuclide-specific analyses usually needed


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4. Thermal processes for extraction, processing

and combustion of minerals

Includes:

Metal production/refining by melting or reduction

Recycling of scrap

High temperature separation of minerals

Calcining (roasting to decompose hydrates, carbonates etc. and to expel volatile material)

Combustion of fossil fuels Main radiological concern is exposure to furnace fume and dust

Low boiling point radionuclides are volatilized (e.g. 210Pb, 210Po and sometimes Ra isotopes)

Volatilized radionuclides condense in scrubbers, filters and stacks — risk of inhalation of airborne dust during maintenance

Non-volatilized radionuclides tend to migrate to slag, ash, scale — possible risk due to gamma radiation or airborne dust during disposal or use as by-product


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4. Thermal processes for extraction, processing

and combustion of minerals

Melting of scrap steel in an arc furnace


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NORM Residues

• Large volumes - 104-106 tonnes/ or more per year per facility

• Residues may be chemically toxic and/or radioactive

• Residues can range from dry solids (varying from rocks to fine powders),

through slurries to liquids containing

dissolved material

• 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 to cause detriment needs

to be considered when planning the

management of NORM residues.


Often occurs in large quantities


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Residues: properties

• Scale: few Bq/g.. or even up to 1000 Bq/g Ra-226

• Possibility for inhomogeneous activity distribution

• If scale are of Ra-type, hot spots can be identified by gamma measurements

• For Pb-210 scale, beta-sensitive equipment must be used

• Required radionuclide chracterisation


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Protection and safety considerations

• Occupational Health and Safety in place

• Ventilation – in confined areas and underground mines

• Spillage and contamination

• Potential for personal contamination in chemical process plants

• Follow the RP rules

• Use personal protective equipments where appropriate

• Radiation protection to be tailored to the particular type of industry or process


Industry sectors of interest

1. Uranium mining and processing 2. Rare earths extraction SR68 3. Thorium extraction & use 4. Niobium extraction 5. Non-U mining – incl. radon 6. Oil and gas SR34 7. TiO2 SR76 8. Phosphates SR78 9. Zircon & zirconia SR51 10. Metals production (Sn, Cu, Al, Fe, Zn, Pb) 11. Burning of coal etc. 12. Water treatment – incl. radon

The following industry sectors have been identified, roughly in descending order, as being the most likely to require some form of

regulatory consideration


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For Industrial NORM issues –

IAEA Safety Reports Series


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The NORM Symposia

Amsterdam, Netherlands 1997

Krefeld, Germany 1998 (NORM II)

Brussels, Belgium 2001(NORM III)

Szczyrk, Poland 2004 (NORM IV)

Seville, Spain 2007 (NORM V)

Marrakesh, Morocco 2010 (NORM VI)

Beijing, China 2013 (NORM VII)


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Other documents


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