| Summary: | BackgroundThe main ore-bearing rock of the Husab Uranium Mine in Namibia, southern Africa, is white granite, and the radioactive element thorium content in the ore is high, which has a greater impact on the γ ray logging results.PurposeThis study aims to solve the problem of thorium's interference on the γ ray logging results by developing a γ ray spectrum logging instrument.MethodsA high-resolution LaBr3(Ce) scintillation detector was employed to build a new type of γ ray spectrum logging tool. Combined with cross-segment method of γ ray spectrum and techniques for separating the γ ray spectrum, the counting rates of thorium, uranium and potassium nuclides were greatly improved, so did the measuring range of the tool and logging speed. Experiment and calibration tests of this logging instrument were conducted on control holes, blast holes, national standard uranium calibration pit, etc., to verify its range, speed applicability, stability, repeatability, etc.ResultsTests results show that the γ ray spectrum logging achieves upper limit of uranium content measurement of 5.0% eU, and the logging speed of 0.067 m·s-1, satisfying the rapid quantitative measurement of uranium grades in the blast holes of the Husab Mine and accurately estimated the amount of uranium with superior measuring accuracy to the γ ray logging method.ConclusionsThe γ ray logging tool of this study reaches specification requirements of γ ray logging. It can effectively distinguish thorium, uranium and potassium nuclides, realizing the quantitative measurement of uranium content.
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