Second biannaul recalibration of two spectral gamma-ray logging systems used for baseline characterization measurements in the Hanford Tank Farms

The U.S. Department of Energy`s (DOE) Grand Junction Projects Office (GJPO) is establishing an initial, or baseline, characterization of gamma-ray-emitting contaminants in the subsurface of the Tank Farms at the DOE Hanford Site in the State of Washington. These baseline data are gathered by logging existing monitoring boreholes with two high-resolution passive spectral gamma-ray logging systems (SGLSs) informally known as Gamma 1 and Gamma 2. Calibration of the logging systems is crucial to the assurance of data quality. The project document Vadose Zone Monitoring Project at the Hanford Tank Farms, Spectral Gamma-Ray Borehole Geophysical Logging Characterization and Baseline Monitoring Plan for the Hanford Single-Shell Tanks specifies that both systems must be recalibrated, using the calibration standards at the Hanford borehole logging calibration center, every 6 months. DOE presents a description of the first recalibrations