METHOD FOR DIRECT INTERFERENCE-RESISTANT DETERMINATION OF URANIUM CONTENT DURING LOGGING BY INSTANTANEOUS FISSION NEUTRONS

摘要

The invention is related to methods for direct interference-resistant determination of uranium content Cu and linear uranium reserves Qu by the technique of logging by instantaneous fission neutrons (LFNi) during search, survey and, primarily, recovery of hydrogenous-type uranium deposits by the borehole underground leaching method. The objective of the proposed method is higher accuracy of Cu and Qu determination by way of suppression of main interferences from uncontrolled variations of ore moisture content W and borehole diameter Dc. The technical result consists in ensuring the standard accuracy of Cu and Qu determinations, control of the accuracy, applicability of the method for lean ores, and determination of W. Said technical result is achieved by LFNi conduction using a dual-probe pulsed neutron generator, the method comprising measurement of the generator output by a monitor (J_mon); measurement of an integral time spectrum of epithermal instantaneous fission neutrons (J_ifn) at the nearer IFN probe (Z_ifn); measurement of a differential time spectrum of the generator thermal neutrons at the farther TN probe (Z_tn), finding on its basis an integral spectrum (J_tn) and asymptotic decay decrement (λ_tn) of thermal neutrons at the TN probe; recalculating, on the λ_tn basis, the lifetime of instantaneous fission neutrons at the IFN probe (τ_ifn); determination of Cu from the ratio of normalized IFN and TN spectra, MT=[J_ifn (Z_ifn, T_ifn)/J_mon(Z_ifn)]/[J_tn(Z_tn, T_tn)/J_mon(Z_tn)], measured at lengths of Z_ifn, Z_tn probes and at cutoff times T_ifn, T_tn optimized by the criterion of minimizing influence of interferences from W and Dc variations; determination of W from λ_tn decrement and J_tn count rate in a wide time window.