Pulsed neutron uranium borehole logging with prompt fission neutrons

Conference · Thu Jan 01 04:00:00 EST 1976

OSTI ID:7125703

Bivens, H M; Smith, G W; Jensen, D H

The gross count natural gamma log normally used for uranium borehole logging is seriously affected by disequilibrium. Methods for the direct measurement of uranium, such as neutron logging, which are not affected by disequilibrium have been the object of considerable effort in recent years. This paper describes a logging system for uranium which uses a small accelerator to generate pulses of 14 MeV neutrons to detect and assay uranium by the measurement of prompt fission neutrons in the epithermal energy range. After an initial feasibility study, a prototype logging probe was built for field evaluation which began in January 1976. Physical and operational characteristics of the prototype probe, the neutron tube-transformer assembly, and the neutron tube are described. In logging operations, only the epithermal prompt fission neutrons detected between 250 microseconds to 2500 microseconds following the excitation neutron pulse are counted. Comparison of corrected neutron logs with the conventional gross count natural gamma logs and the chemical assays of cores from boreholes are shown. The results obtained with this neutron probe clearly demonstrate its advantages over the gross count natural gamma log, although at this time the accuracy of the neutron log assay is not satisfactory under some conditions. The necessary correction factors for various borehole and formation parameters are being determined and, when applied, should improve the assay accuracy.

• Research Organization: Sandia Labs., Albuquerque, NM (USA)
• DOE Contract Number: E(29-1)-789
• OSTI ID: 7125703
• Report Number(s): SAND-76-9100; CONF-761059-12
• Country of Publication: United States
• Language: English

Related Subjects

050200* -- Nuclear Fuels-- Exploration-- (-1987)
11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS
440400 -- Well Logging Instrumentation
47 OTHER INSTRUMENTATION
BARYONS
ELEMENTARY PARTICLES
EQUIPMENT
FERMIONS
FISSION NEUTRONS
GEOLOGIC DEPOSITS
HADRONS
NEUTRON LOGGING
NEUTRON-NEUTRON LOGGING
NEUTRONS
NUCLEONS
PERFORMANCE TESTING
PROMPT NEUTRONS
PULSED NEUTRON TECHNIQUES
RADIOACTIVITY LOGGING
RESOURCES
TESTING
URANIUM DEPOSITS
WELL LOGGING