sxr southern cross resources inc pfn technology: prompt fission neutron deposit evaluation sxr...
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SXRSouthern Cross Resources Inc
PFN Technology:
“Prompt Fission Neutron”
Deposit Evaluation
SXRSouthern Cross Resources Inc
SXRSouthern Cross Resources Inc
U238 Th234 Pa Th230 Ra Rn Bi Pb214 Pb206
Gamma Ray Intensity
238U
214Bi214Pb
Gamma is the traditional tool
used to measure eU3O8 grade
and evaluate resources…
…but in some Roll-front
deposits uranium is not in
equilibrium with its daughters
as they are too young.
PFN: Disequilibrium Problem
SXRSouthern Cross Resources Inc
Hole 1
ReducedAquifer
Basement Clay
Overlying Clay
NoseTails Uranium OreOxidisedAquifer
Gamma Response
PFN: Schematic Gamma Response
Hole 2 Hole 3 Hole 4
SXRSouthern Cross Resources Inc
Hole 1
PFN: Schematic PFN Response
Hole 2 Hole 3 Hole 4
No PFN response in low grade tails as daughters only
PFN response directly measures 235U concentrated in high grade nose
SXRSouthern Cross Resources Inc
Pulsed Neutron Source
Down Hole Probe
Drill Hole
PFN: What is PFN Technology?
SXRSouthern Cross Resources Inc
PFN: Neutron Generator Tube
• High voltage accelerates deuterium (2H) ions into a tritium (3H) target2H + 3H n + 4He (En =
14.2MeV)
• Pulses at 1000 cycles per second & emits ~108 neutrons per second
SXRSouthern Cross Resources Inc
Pulsed Neutron Source
Epithermal & Thermal Neutron
Detectors
Ratio gives % 235U
14 MeV Neutron Flux
Epithermal Neutron
To Thermal Neutron
(by Collision with rock)
Thermal Neutrons Induce Slow Fission of Natural 235U in rocks
2MeV Prompt Neutrons emitted from 235U fission
Down Hole Probe
Drill Hole
PFN: What is PFN Technology
SXRSouthern Cross Resources Inc
• Ratio of Epithermal to Thermal Neutrons is Directly Proportional to 235U
• Only 235U is Fissionable in the Natural Environment
• Deposits considered in Isotopic Equilibrium 0.72% 235U
99.27% 238U
1.48 U3O8 lbs/ft3
0.27 U3O8 lbs/ft3
3.52 U3O8 lbs/ft3
Thermal Neutron
Flux
Epithermal Neutron
Flux
PFN Results
SXRSouthern Cross Resources Inc
PFN: Calibration
Legend & Notes
Corrugated Polyethylene Moulded Tank
Washed River Sand mixed with Aquifer Water & dosed with Yellowcake
PVC Class 12 Casing & FlangesOil Layer (to prevent evaporation)Water (Aquifer)Acrylic CasingCorkTrenchBackfilled SoilConcrete Apron
1) BLANK120mm ID
2) LOW0.058% U3O8
120mm ID
3) MEDIUM0.172% U3O8
145/120/95mm ID
4) HIGH0.825% U3O8
120mm ID
1.7m
7m
Lockable PVC Flange
300mm
100mmConcrete Apron
PVC Casing
Acrylic CasingOil Layer
PVC End Cap
Cork Block
Sand / Water / Yellowcake Mixture
BackfilledSoil
Trench Floor
900mm
1.5m
1m Diameter
Acrylic Casing Sizes 95mm ID = 101mm OD 120mm ID = 127mm OD 145mm ID = 152mm OD
Pits 3 three casing sizes for Hole Size Correction Factor(min. 300mm separation)
S O U T H E R N C R O S SRESOURCES AUSTRALIA PTY LTD
Honeymoon PFN Calibration Test Pits
C P Skidmore (26 September 2003)
Rubber Expansion Seal
SXRSouthern Cross Resources Inc
PFN Calibration Results
PFN Grade Calibration
y = 0.4686x - 0.0057R2 = 1
0.000
0.100
0.200
0.300
0.400
0.500
0.600
0.700
0.800
0.900
0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2
En/ Tn
%U
3O
8
PFN Bore Hole Correction Factor
0.6
0.8
1
1.2
1.4
1.6
1.8
2
90 100 110 120 130 140 150 160 170 180 190 200
Diameter (mm)
BH
CF
Aquifer Water
Dry
Drilling Mud
RO Water
SXRSouthern Cross Resources Inc
Wireline Log Outputm%(Eyre Fm Basal Sand Only)Cumulative GT1.13
Hole IDHML024
InterpretationColin SkidmoreDate14/3/2004LocationHoneymoon Scoping 2004070000CPS070000CPS10007000CPS15000mS/m0.032% U3O820.03% U3O81m:175m
Induction & Guard- Define lithology by
measuring porosity using EM and Electrical methods. Similar to SP / Resistivity but better suited to highly saline conditions
Natural Gamma- Total count natural
gamma radiation measured by up to three scintillometers with varying NaI crystals sizes
eU3O8 (Black)
- Calculated from calibrated natural gamma using a number of factors)
pU3O8 (Red)- Direct measure of
U235 insitu using ration of epithermal to thermal neutrons – PFN
SXRSouthern Cross Resources Inc
PFN: Advantages
• Crucial for most Tertiary Uranium deposits as they are young and suffer
extreme disequilibrium
• Uses a safe neutron generator rather than a radioactive source
• Produces an accurate direct measurement of insitu uranium over narrow
intervals
• Results are instantaneous
• Measures a large sample volume (500mm sphere)
• Obviates the need to drill core
• Can be used during ISL mining to quantify recovery
• Exploration tool – disequilibrium vector towards mineralisation
Colin Skidmore (October 2005) [email protected]