A nuclear gage for in-place measurement of sediment density

Document Type

Conference Proceeding

Date of Original Version



A nuclear gage for measuring sediment density in place is being developed under an Atomic Energy Commission contract. This gage will be added to the Deep Ocean Sediment Probe (DOSP), a multi-sensor system. The gage uses a gamma radiation isotope source in a concurrent transmission and backscatter arrangement. Direct correlation with undisturbed cores and acoustic data from the DOSP is possible. An electrical resistivity sensor is being added and will provide additional in place data for correlation. Results of testing both laboratory and prototype design configuration are presented. Transmission gages are usually superior to backscatter gages but require a two probe fork arrangement which is more difficult to force into sediments than a single probe backscatter type arrangement. In the design presented, the backscatter gage arrangement has been optimized to approach transmission results by special design of radiation shields around the isotope source and radiation detector and by the design of energy level discriminating circuits in the. instrumentation. This design limits the zone of material sensed to a well defined volume and avoids variations in readings resulting from changes in chemical composition of the sediment.

Publication Title

Proceedings of the Annual Offshore Technology Conference