Uranium logging with prompt fission neutrons

Abstract This paper descirbes a uranium logging probe which can assay U3O8 concentrations as low as 100 ppm at 0.5 m/min. The probe sends 100 pulses per second of 14 MeV neutrons (2 × 106 neutrons/pulse) into the formation surrounding a borehole, and detects prompt epithermal neutrons returning from fissioning 235U. Various models of the probe have logged hundreds of boreholes in the Western United States since 1976. The neutron generator is now commercially available and the probe design is available to the public.