Calibration facilities at Hanford for gamma-ray and fission-neutron well logging
Well-logging tools that detect gamma rays emitted from earth formations need to be calibrated in appropriate facilities to provide quantitative assessments of concentrations o radionuclides based on detected gamma rays. These facilities are typically special models having a hole to insert tools and having sufficient physical size to simulate actual earth formations containing known amounts of radionuclides. The size, generally 3 to 5 feet in diameter and 4 to 6 feet tall, is such that the source of radiation appears infinite in extent to a tool detecting the radiation inside the model. Such models exist at Hanford as concrete cylinders having a central borehole and containing known, enhanced amounts of K, U, and Th. Data collected in these models allow calibration of the logging system to measure radionuclide concentrations in formations around boreholes in the field. The accuracy of the calculated field concentrations depends on the correctness of the original calibration, the statistical precision of the data, and the similarity of the logging conditions to the calibration conditions. Possible methods for analyzing the data collected in the calibration facilities are presented for both spectral and total-count gamma-ray systems. Corrections are typically needed for the effects of steel casing in boreholes and the presence of water rather than air in the holes. Data collected in the calibration models with various steel casings and borehole fluids allow such correction factors to be determined.
- Research Organization:
- Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
- Sponsoring Organization:
- USDOE, Washington, DC (United States)
- DOE Contract Number:
- AC06-76RL01830
- OSTI ID:
- 10169983
- Report Number(s):
- PNL-9958; ON: DE94015880; TRN: 94:014782
- Resource Relation:
- Other Information: PBD: Jul 1994
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
54 ENVIRONMENTAL SCIENCES
HANFORD RESERVATION
CALIBRATION STANDARDS
GAMMA LOGGING
WELL LOGGING EQUIPMENT
CALIBRATION
WELL CASINGS
CORRECTIONS
RADIOECOLOGICAL CONCENTRATION
DATA ANALYSIS
440400
540230
WELL LOGGING INSTRUMENTATION
RADIOACTIVE MATERIALS MONITORING AND TRANSPORT