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Prompt Fission Neutron (PFN) Borehole Logging Technology, Comparison with
Gamma Logging Techniques
AusIMM International Uranium Conference
Adelaide June 2010
www.uxa.com.au
ASX: UXA
Russell Penney and Dennis Stevens
AcknowledgementsAcknowledgementsAcknowledgementsAcknowledgements
Uranium Exploration Australia Limited (UXA) thanks UraniumSA Limited for permission to present data from their Mullaquana uranium discovery in South Australia.
DisclaimerDisclaimerDisclaimerDisclaimer
This presentation does not comprise a disclosure document. It does not constitute provision of financial product advice. None of the directors of UXA, its related bodies corporate, officers, employees or advisors makes or gives any representation, warranty or guarantee in relation to this presentation (whether orally, in document form or in any form whatsoever) or in relation to any information (“Information”) contained in it to the recipient of this presentation or any of its related bodies corporate, officers, employees and advisors (“Recipient(s)”). Information sourced from third parties and reported in this presentation has not been verified or updated; it is important that Recipient(s) take care to verify and update before taking in to account in any process of evaluation. The presentation is provided expressly on the basis that the Recipient(s) will carry out its own independent inquiries into the Information and make its own independent decisions about the affairs, financial position or prospects of UXA. UXA reserves the right to update, amend or supplement the Information at any time in its absolute discretion (without incurring any obligation to do so).
� Unique borehole logging tool provides immediate and fool-proof uranium analysis within the borehole by using neutron activation to measure 235U
� PFN used in discovering Australia's most recent uranium mine – Beverley – and the Four Mile mine development in South Australia and is in daily use at many uranium mines in the USA
� UXA recently purchased the PFN business and intellectual property from its owner in the USA
� PFN technology is owned 100% by UXA and is available from GAA, an independently managed borehole logging company, a 100% owned subsidiary of UXA
238U decay chain
gamma
gamma
Spectral gamma energy windows typical of airborne surveys, hand-held spectrometers and downhole gamma tools
� Total Gamma includes gamma radiation derived from the decay of Potassium, Thorium, Lead and Bismuth
� Spectral Gamma uses energy windows to differentiate the origin of each gamma particle.: e.g. most airborne radiometric surveys
� Spectral Gamma tools measure the daughter products of 238U to determine Uranium grade
� Both Total Gamma and Spectral Gamma tools suffer from disequilibrium issues
Many uranium deposits too
young for uranium and gamma
emitting daughter elements to
be in equilibrium (7 half lives of
the longest living daughter
element = 560,000 years)
Uranium may also have
migrated away from its
daughter elements by chemical
action
Gamma, in this example,
“misses” a significant zone of
uranium
PFN
Source: Natural Decay Series: Uranium, Radium, and Thorium;
Human Health Fact Sheet, August 2005, Argonne National Laboratories, EVS
UUUU238238238238
ThThThTh234234234234
β
α
PaPaPaPa234234234234
UUUU234234234234
βα
ThThThTh230230230230
α α αRaRaRaRa
226226226226RnRnRnRn
222222222222α
PoPoPoPo218218218218
PbPbPbPb214214214214
β
γ
Bi214
β
Po214
γ
αPb
210
β
Bi210
β
Po210
αPb
206
α
β
γ
= alpha decay radiation
= beta decay radiation
= gamma radiation
Gamma can be used to calculate
uranium concentration as eU3O8
[ Indirect determination]
Valid only if daughters inequilibrium with parent!
4.5x109 Yrs
24.5 days
1.14 mins
2.33x105 Yrs 8.3x104 Yrs 1590 Yrs 3.825 days3.05 mins
26.8 mins
19.7 mins
1.5x10-4 secs 22 Yrs
5 days
140 days Stable
� PFN tool creates very fast neutrons (14MeV) and fires 108
neutrons per second
� Neutrons are slowed (Thermal) by collisions with the rock
� The generated neutrons collide with 235U and splits the atom (Fission)
� Fast (Epithermal – 2MeV) neutrons are produced
� PFN measures the ratio of epithermal(fast) and thermal(slow) neutrons
�235U is the only fissile material in the natural environment
� The Ratio of Epithermal to Thermal Neutrons is proportional to 235U
� Uranium is in Isotopic Equilibrium ◦ 0.72% 235U
◦ 99.27% 238U
� Therefore % U3O8 may be deduced from PFN results directly.
� Calibration at AMDEL facility run by DWLDC in Adelaide
� Three pits of various grades of U3O8
� Barren zone also recorded
� Hole Correction Pit –calibration for three different hole diameters
� Both Gamma and PFN components of the tool are calibrated in these pits
Mine sites have their own calibration pits
� Multiple runs are used to check repeatability and ascertain a ratio of epithermal/thermal for a particular known grade of U3O8 gamma PFN
y = 1.9378x - 0.0148
R² = 0.9999
0
0.5
1
1.5
2
0 0.1 0.2 0.3 0.4 0.5 0.6
%pU3O8
Ratio Epi/Thermal
PFN
Linear (PFN)
Gra
de in p
it
� Corrections for wet/dry hole situations◦ Dry holes decrease correction factor. Difficult to provide quantitative results due to hole rugosity
� Aquifer fluid correction factor◦ Higher salinity – higher correction factor
� Porosity◦ Higher porosity = higher aquifer fluid
� Drill hole size correction
y = 0.8933ln(x) - 3.1862
R² = 0.9992
0.50
0.70
0.90
1.10
1.30
1.50
1.70
1.90
2.10
2.30
2.50
50 100 150 200 250
Correction factor
Hole size (mm)
Hole Size
Log. (Hole Size)
HQ
PQ
In this example, Uranium and its
daughter products are in
Equilibrium
U Grade from gamma logging is
denoted as “% eU3O8”
U Grade from PFN logging is
denoted as “% pU3O8”
PFN = Blue LineGamma = Red Line
0.15%
An absence of Uranium occurs at a
gamma peak at 35.8m
This log demonstrates the necessity
of PFN in defining uranium, and in
quantifying the amount of uranium.
Note the “Negative” or “Positive”
Disequilibrium in the right hand
column
PFN = Blue LineGamma = Red Line
PFN = Blue LineGamma = Red Line
1.10%
0.65%
Low grade Uranium in a hard rock environment
Uranium from a Tertiary Basin deposit
PFN = Blue LineGamma = Red Line
0.15%
0.03%
0.01%
Low grade Uranium in a hard rock environment - equilibrium
Uranium from a calcrete hosted depositFluctuating groundwater causes disequilibrium
PFN = Blue LineGamma = Red Line
0.03%
Gamma log alone does not reveal a true picture of U distribution
PFN (red) shows the strong disequilibrium with little uranium in the “wings” of the deposit
The PFN tool can be used
to guide exploration by
following disequilibrium
vectors to find the
displaced uranium
PFN = Blue LineGamma = Red Line
PFN Currently
being used at a
number of
uranium mines in
the US
Sandstone-hosted
U deposits with
roll-fronts
� Gain certain knowledge of the presence and amount of Uranium downhole as opposed to measuring 214Bi and 214Pb with gamma
� Provides instant results to aid drill program adjustments instead of waiting for geochemical analysis
� Analyses a larger mass of host rock than core or cuttings
� Reduces analytical costs – (reduce labour cost from collecting, handling and transporting radioactive substances and in geochemical assay costs and storage)
� Reduces drilling costs (no need to core)
PFN TECHNOLOGY (WORLDWIDE) IS PFN TECHNOLOGY (WORLDWIDE) IS
AVAILABLE FROM GAAAVAILABLE FROM GAA
GAA also provides a wide range of geophysical borehole logging technologies, including Gamma
Logging
Contact details:
Dr Russell Penney
[email protected]+61 8 8363 7970www.uxa.com.au
ASX: UXA
Uranium Exploration Australia LimitedRegistered Office in Adelaide, South Australia
43a Fullarton RoadKent Town, SA 5067