PFN Technology: “Prompt Fission Neutron” Deposit Evaluation PFN Technology: “Prompt Fission Neutron” SXR Southern Cross Resources Inc
PFN: Disequilibrium Problem Gamma is the traditional tool used to measure eU3O8 grade and evaluate resources… g Gamma Ray Intensity 214Pb 214Bi Gamma measures radioactive Bismuth & Lead (the daughter products of uranium decay) not Uranium itself. Disequilibrium occurs when deposits are younger than ~1 million years old and gamma under calls true uranium grade. …but in some Roll-front deposits uranium is not in equilibrium with its daughters as they are too young. 238U
PFN: Schematic Gamma Response Hole 1 Hole 2 Hole 3 Hole 4 Overlying Clay Oxidised Aquifer Reduced Aquifer Tails Uranium Ore Nose Example of gamma response. High levels in the tails, low to no response in the nose. Basement Clay Gamma Response
PFN: Schematic PFN Response Hole 1 Hole 2 Hole 3 Hole 4 Example of gamma response. High levels in the tails, low to no response in the nose. No PFN response in low grade tails as daughters only PFN response directly measures 235U concentrated in high grade nose
PFN: What is PFN Technology? Down Hole Probe Pulsed Neutron Source Haliburton Neutron Generator Tube gives controlled bursts of high energy neutrons 1000 per second. Drill Hole
PFN: Neutron Generator Tube Haliburton Neutron Generator Tube gives controlled bursts of high energy neutrons 1000 per second. High voltage accelerates deuterium (2H) ions into a tritium (3H) target 2H + 3H n + 4He (En = 14.2MeV) Pulses at 1000 cycles per second & emits ~108 neutrons per second
PFN: What is PFN Technology Down Hole Probe 14 MeV Neutron Flux Epithermal Neutron To Thermal Neutron (by Collision with rock) Pulsed Neutron Source Thermal Neutrons Induce Slow Fission of Natural 235U in rocks PFN neutron detection. Ratio of Thermal (output) to Epithermal (U235 fission product) neutrons is directly proportional to true in-situ uranium grade. Epithermal & Thermal Neutron Detectors Ratio gives % 235U 2MeV Prompt Neutrons emitted from 235U fission Drill Hole
Epithermal Neutron Flux PFN Results Thermal Neutron Flux 3.52 U3O8 lbs/ft3 Epithermal Neutron Flux 1.48 U3O8 lbs/ft3 0.27 U3O8 lbs/ft3 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
PFN: Calibration
PFN Calibration Results
Wireline Log Output Induction & Guard eU3O8 (Black) Natural Gamma - Define lithology by measuring porosity using EM and Electrical methods. Similar to SP / Resistivity but better suited to highly saline conditions eU3O8 (Black) - Calculated from calibrated natural gamma using a number of factors) Natural Gamma - Total count natural gamma radiation measured by up to three scintillometers with varying NaI crystals sizes pU3O8 (Red) - Direct measure of U235 insitu using ration of epithermal to thermal neutrons – PFN
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) cskidmore@sxru.com