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Nuclear TechniquesUranium ExploratioSUBMITTED TO:
DR. ABID
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Group Members
Name Registration No.
Ali Ammar MSPE-1323
Arslan Arshad MSPE-1333
Ahtisham Arshad MSPE-1332
Muhammad Mujahid MSPE-1328
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Synopsis
Exploration
Objectives of Exploration
Exploration Techniques
Nuclear Techniques
Gamma Survey
Radon Survey
Neutron Activation
Delayed Neutron Counting
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Exploration
AnalysisQuantity
Quality
Several exploration techniques are used, dependingtype of deposit and its proximity to the surface.
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Objectives of ExplorationEstablish baseline/background conditions
Find alteration zones
Find ore body
Determine if ore can be mined or leached
Determine if ore can be processed
Determine ore reserves
Locate areas for infrastructure/operations
Environmental assessment
Further understand uranium deposits
Refine exploration models
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Exploration Steps
Area SelectionReconnaissance
phaseFollow up Phase Detailed Phase
Locate area ofinterest
Locate exactly on theground the extent
anomalies in area ofinterest
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Fundamental Parameters
Physical Properties
Form of Mineralization
Accumulation in Host Rock
Abundance
Age of Rock
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Uranium as Mineral Deposit
Uranium (U) has an average crustal abundance of 23 ppm
Minerals with uranium as a major constituent include uraninite (pitcbetafite, coffinite and several others
While those with uranium as a minor constituent include zircon, xenmonazite, orthite, apatite, and sphene
Uranium has three radioactive isotopes 238U (99.274%, T1/2= 4.5 1235U (0.720%, T1/2= 7.13 10
8years) and 234U(0.006%)
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Physical Properties
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Exploration TechniquesMagnetic Surveys
Electromagnetic (EM, EMI), Electromagnetic Sounding
Direct Current (DC)
GPR (Ground penetrating radar potential)
Seismic
Time-Domain Electromagnetic (TEM)
Controlled source audio-Magnetotellurics (CSAMT)
Radiometric Surveys
Induced Polarization (IP)
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Exploration Techniques (Contd..
Spontaneous potential (SP)
Borehole geophysics
Satellite imagery
Imagery spectrometry
ASTER (Advanced space-borne thermal emissions reflection radiometer)
Multispectral
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Exploration Techniques
Radiometric SurveysGamma Survey
Radon Survey
Analytical Techniques
Neutron Activation
Delayed Neutron Counting
X-ray Fluorescence Analysis
Fluorometry
Spectrophotometry
Gravimetric and Volumetric Analysis
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Radioactivity
The atomic nuclei of some isotopes are unstable, disintegrate and form a neaccompanied by emission of particles or energy, termed nuclear radiation.
Nuclides with this feature are called radionuclides.
The radioactivity decay law expresses the decrease in the original number oof a radionuclide with time (t)
Nt= Noet
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Measurement and Units
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Nuclear Radiation and Interactio
Potassium, uranium and thorium are naturally occurring radioactive elemenabundance in the rocks throughout the world. The emitted radiation of therelatively intense and easily measured in the field.
Alpha Radiation (positively charged alpha particles of relatively great mas
Beta Radiation (electrons)
Gamma Radiation (electromagnetic, and its rays are specific for a particu Photoelectric Effect
Compton Scattering
Pair Production
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Gamma SurveyThe most important elements contained in crustal rocks that make up the bmeasurable terrestrial gamma radiation are potassium, uranium and thoriu
The total measured radiation can be represented by the equation
Itotal= Irocks+ Icosm+ Iradon+ ICs
Irocks = Radiation due to rocks
Icosm = Cosmic rays
Iradon = Radiation due to atmospheric radon
ICs = Radiation due to Cesium (Areas which are influenced by Fallout)
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Gamma Survey (Contd..)
Gamma radiation of a point source (small geological object) with a radioelem, is reduced by the square of the sourcedetector distance r (m), and attethe mass of environment of this path; attenuation for given energy of gammspecified by the linear attenuation coefficient (m-1).
I = (km/r2) * e-r
where k is the constant expressing gamma radiation of a particular radionuc
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Gamma Survey (Contd..)
Environmental factors that can significantly affect observed gamma ray fielWeathering Overburden
Dense Vegetation
Increase in Soil Moisture
Weathering overburden will attenuate the gamma radiation, dense v
cause the reduction in the gamma radiation and the last will also reducradiation and the measured radiation will be much lesser than the original
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Gamma Survey (Contd..)
Gamma ray surveying is conducted as a total count survey or gamma ray spTotal count surveys (TC) with scintillation count rate meters are applied to gmeasurements and to borehole logging. The relationship between the recorate, nTC(counts/s), and the concentration of K, U, and Thorium in the grou
nTC= SKCK+ SUCU+ SThCTh
where SK, SU, SThare the sensitivities of the TC instruments (counts/s per uconcentration of relevant radionuclide), and CK, CU, and CThare radioelemeconcentrations.
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Gamma Survey (Contd..)
Airborne gamma ray spectrometry has been used over many years for uranexploration and spectrometers have scintillation detectors.
Car-borne gamma ray spectrometry is another platform for surveying and in car-accessible terrain. A car-borne multichannel gamma ray spectrometehas a NaI(Tl) scintillation detector.
Gamma logging in boreholes involves a TC technique or gamma ray spectro
NaI(Tl) or CsI(Tl) scintillation crystals installed in the logging probe have limiand therefore limited size.
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Gamma Survey (Contd..)Scintillators:
The operation of a scintillation counter may be divided into two broad steps:
Absorption of incident radiation energy by the scintillator and production of photovisible part of the electromagnetic spectrum
Amplification of the light by the photomultiplier tube and production of the outpu
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Scintillators
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Gamma Survey (Contd..)Solid State Detectors:
The term solid state detectors refers to certain classes of crystalline substwhich exhibit measurable effects when exposed to radiation.
Difference in energy produced by excitation and de-excitation of electronsthe fluorescent radiations.
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Gamma Survey (Contd..)The Geiger Muller Counter:
It is based on the ionization of gas in chamber which is connected to anodcathode.
The flow of the ions produces the current which the measure of incident r
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Geiger Muller Counter
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Radon Survey
Originated from the decay of uraniumUsed as an indicator and is a source of alpha radiations
Uranium ore body exhibit radon activity concentration of the order of 10decreases with distance
Activity Concentration of Radon
CA= am* * kem/p
Radon (222Rn) activity concentration cA(Bq/m3) in soil gas, mass activity amo
(Bq/kg), density of the rock (kg/m3), emanation power kemand rock poros
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Radon Survey (Contd..)Radon Movement is due to:
Diffusion
Convection
Diffusion depends on the diffusion coefficient of the soil and the radon decay const
CAx= CA0e-x/D
Convection is caused by:
Underground Water
Temperature Gradient
Pressure and Tidal Effects
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Radon Survey (Contd..)
Emanometers:
These are the radon detectors which measure the alpha activity of the soi
Sample is placed in ionization chamber where the alpha particles are releadisintegration of radon
These Particles are then counted and registered
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Flow Path
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Radon Survey (Contd..)
Alpha Track Methods:
Based on the registration of radon alpha particles on the sensitive film
Cups with sensitive film are placed in pits covered by soils left for 20-30 d
Density of alpha tracks recorded on the film is a measure of radon in soil g
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Radon Survey (Contd..)
Alpha Card Method:
Alpha card is a paper frame with a circular, aluminum-coated Mylar collect
It detects the radioactivity of radon solid products as they accumulate on placed in the pit for 1-2 days
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Radon Survey (Contd..)
The Radon on Activated Charcoal (ROAC):
This method is based on the adsorption of radon gas on activated charcoa
Charcoal in a plastic container is placed into a pit for an exposure period odays.
The gamma radiation of radon decay products balanced with the quantityradon on activated charcoal is counted.
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ROAC Kit
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Radon Detection
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Neutron Activation
A useful, sensitive and accurate method used for uranium is neutron activanalysis.
It can be carried out by any source of thermal neutrons, but usually requirreactor.
An atom of 238U captures the neutron and converted into 239U which in turbeta emission with half life of 23.5 minutes to 239Np
In turn 239Np decaying by beta emission having half life of 2.36 days conve239U. Which can be used to determine the quantity of uranium in the sampl
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Neutron Activation
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Seismic Imaging
Estimates the seismic characteristics of the Earthssurface.
Acoustic energy waves are sent
Every mineral has different hardness, density, and porosity.
Intensity & time of reflected sound is measured.
How long it took to receive reflected sound wave. This data
tells where rock properties changes.
Reflected acoustic energy waves are measured. Vibrators or detonators are used for sound waves.
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Seismic Imaging
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Magnetic ImagingMagnetic field characteristics measured.
Minerals have distinct & different intensity magneticfields.
Magnetometer is mounted on an operator or on aeroplane or helicopter.
Magnetic surveys can be done on ground or aerially.
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Magnetic Imaging
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Gravity MethodMeasurements of the gravitational field at a series
of different locations over an area of interest. Theobjective in exploration work is to associate variationswith differences in the distribution of densities andhence rock types.
Dense and heavy rocks, due to their extragravitational attraction increases the downward pulland creates positive gravity anomalies (gravity
highs).
Where the rocks are light, the gravitational pull isdiminished and the anomalies are negative (gravitylows).
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Geological Mapping (Results)
A way to gather & present geologic data.
By assembling different ground radiationdatasets a dose rate map of Uranium could beconstructed.
Shows how rock & soil on the earths surfaceis distributed.
Help to come up with a model for an orebody.
Show other features such as faults and strikeand dips.
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THANK YOU