There are several hundred thousand nuclear gauges incorporating a radioactive source or a radiation generator in use all over the world. They have been used in a wide range of industries to improve the quality of products, optimize processes, and save energy and materials. The economic benefits have been amply demonstrated, and there is clear evidence that nuclear gauge technology can be used safely and will continue to play an important role. Although generic guidance for source handling is available, there have been no targeted recommendations for radiation safety in the use of nuclear gauges. To fill this gap the current publication provides practical guidance for implementing the safety requirements specified in IAEA Safety Standards Series No. GSR Part 3, Radiation Protection and Safety of Radiation Sources: International Basic Safety Standards, related to the use of nuclear gauges